Knowledgenet Cisco Aironet Wireless Site Survey (Cawss) 4 0 Student Guide
295 31 6MB
English Pages 253
Recommend Papers
- Similar Topics
- Computers
- Networking
File loading please wait...
Citation preview
CAWSS
Cisco Aironet Wireless Site Survey Version 4.0
Student Guide Text Part Number: 67-1801-01
Copyright M 2002, Cisco Systems, Inc. All rights reserved. Cisco Systems has more than 200 offices in the following countries and regions. Addresses, phone numbers, and fax numbers are listed on the Cisco Web site at www.cisco.com/go/offices. Argentina • Australia • Austria • Belgium • Brazil • Bulgaria • Canada • Chile • China PRC • Colombia • Costa Rica Croatia • Czech Republic • Denmark • Dubai, UAE • Finland • France • Germany • Greece • Hong Kong SAR • Hungary India • Indonesia • Ireland • Israel • Italy • Japan • Korea • Luxembourg • Malaysia • Mexico • The Netherlands New Zealand • Norway • Peru • Philippines • Poland • Portugal • Puerto Rico • Romania • Russia • Saudi Arabia Scotland • Singapore • Slovakia • Slovenia • South Africa • Spain • Sweden • Swit zerland • Taiwan • Thailand • Turkey Ukraine • United Kingdom • United States • Venezuela • Vietnam • Zimbabwe
Copyright ã 2002, Cisco Systems, Inc. All rights reserved. CCIP, the Cisco Powered Network mark, the Cisco Systems Verified logo, Cisco Unity, Fast Step, Follow Me Browsing, FormShare, Internet Quotient, iQ Breakthrough, iQ Expertise, iQ FastTrack, the iQ logo, iQ Net Readiness Scorecard, Networking Academy, ScriptShare, SMARTnet, TransPath, and Voice LAN are trademarks of Cisco Systems, Inc.; Changing the Way We Work, Live, Play, and Learn, Discover All That’s Possible, The Fastest Way to Increase Your Internet Quotient, and iQuick Study are service marks of Cisco Systems, Inc.; and Aironet, ASIST, BPX, Catalyst, CCDA, CCDP, CCIE, CCNA, CCNP, Cisco, the Cisco Certified Internetwork Expert logo, Cisco IOS, the Cisco IOS logo, Cisco Press, Cisco Systems, Cisco Systems Capital, the Cisco Systems logo, Empowering the Internet Generation, Enterprise/Solver, EtherChannel, EtherSwitch, GigaStack, IOS, IP/TV, LightStream, MGX, MICA, the Networkers logo, Network Registrar, Packet, PIX, Post-Routing, Pre-Routing, RateMUX, Registrar, SlideCast, StrataView Plus, Stratm, SwitchProbe, TeleRouter, and VCO are registered trademarks of Cisco Systems, Inc. and/or its affiliates in the U.S. and certain other countries. All other trademarks mentioned in this document or Web site are the property of their respective owners. The use of the word partner does not imply a partnership relationship between Cisco and any other company. (0201R)
Table of Contents Course Introduction
1
Overview
1
Course Goal and Objectives Course Outline
Learner Skills and Knowledge Learner Responsibilities General Administration Course Flow Icons and Symbols Learner Introductions Wireless Networking Overview Customer Assistance WLAN Topologies
Impact of WLAN Applications and Design on a Site Survey Overview Module Objectives Module Outline
WLAN Applications WLAN Design Retail Warehousing and Manufacturing Healthcare Hotels and Hospitality Hot Spots Education Offices Transportation Government Summary Review Questions
Manual Site Survey Tools Overview Module Objectives Module Outline
Access Point Selection Site Survey Equipment Summary Review Questions
Manual Site Survey Utilities and Techniques Overview Module Objectives Module Outline
Preparation Indoor Site Survey Concepts Software Tools Summary Review Questions
1 2
3 4 5 6 7 8 9 10 11
1-1 1-1 1-1 1-2
1-3 1-7 1-12 1-18 1-22 1-26 1-30 1-32 1-34 1-36 1-39 1-44 1-45
2-1 2-1 2-1 2-2
2-3 2-5 2-16 2-17
3-1 3-1 3-1 3-2
3-3 3-4 3-20 3-45 3-46
Using the AirMagnet Site Survey Tool for a Manual Survey Overview Module Objectives Module Outline
DSA Coverage AirMagnet Site Survey Tool Manual Survey Situations and Obstacles Summary Review Questions
Assisted Site Survey Techniques Overview Module Objectives Module Outline
Introduction to Assisted Site Survey Technologies Required Cisco Products Density Testing Access Point Radio Scans Client Walkabout Final Testing Displaying a Configured Radio Parameters Report (11b) Displaying a Path Loss Between Managed APs Report (11b) Displaying a Channel Loading Report (11b)
Summary Review Questions
WLAN Design Considerations Overview Module Objectives Module Outline
LAN Infrastructure Cables and Connectors Plenum Firewalls Risers Mounting Securing the Access Point Splitters NEMA Enclosures Summary Review Questions
Documentation Overview Module Objectives Module Outline
Site Survey Preassessment Form Site Survey Report Summary Review Questions
ii
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
4-1 4-1 4-1 4-2
4-3 4-11 4-28 4-39 4-40
5-1 5-1 5-1 5-2
5-3 5-6 5-8 5-11 5-20 5-28 5-32 5-32 5-33
5-36 5-37
6-1 6-1 6-1 6-2
6-3 6-6 6-10 6-13 6-15 6-16 6-20 6-24 6-27 6-31 6-32
7-1 7-1 7-1 7-2
7-3 7-5 7-13 7-14
Copyright © 2004, Cisco Systems, Inc.
CAWSS
Course Introduction Overview Cisco Aironet Wireless Site Survey (CAWSS) v4.0 teaches how to perform site surveys for wireless LAN (WLAN) solution implementations. Presentation material will explore WLAN applications in specific markets, WLAN topologies and design concerns, essential equipment, access point configuration, and site survey techniques. The class will feature instructor-led presentations highlighting both manual and assisted site survey techniques. Successful completion of the Cisco Aironet Wireless LAN Fundamentals (AWLF) course is a prerequisite to taking this course.
Course Goal and Objectives This section describes the course goal and objectives.
Course Goal
To guide the learner to perform manual and assisted site surveys for the wireless LAN environment. Cisco Aironet Wireless Site Survey
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.0 #-3
Upon completing this course, you will be able to meet these objectives: Describe the requirements for a manual and an automated site survey Generate proper documentation of site survey findings, including being able to develop a complete WLAN solution with staging and installation services, and all necessary equipment Describe installation techniques and WLAN infrastructure issues
Course Outline The outline lists the modules included in this course.
Course Outline Impact of WLAN Applications and Design on a Site Survey Manual Site Survey Tools Manual Site Survey Utilities and Techniques Using the AirMagnet Site Survey Tool for a Manual Survey Assisted Site Survey Techniques WLAN Design Considerations Documentation © 2004 Cisco Systems, Inc. All rights reserved.
2
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
CAWSS 4.0 #-4
Copyright © 2004, Cisco Systems, Inc.
Learner Skills and Knowledge This topic lists the course prerequisites.
Prerequisite Learner Skills and Knowledge
AWLF
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS v4.0
CAWSS 4.0 #-5
To benefit fully from this course, you must have these prerequisite skills and knowledge: Knowledge of fundamental networking components and terminology Knowledge of the Open Systems Interconnection (OSI) reference model Knowledge of basic LAN components and functions Successful completion of the Cisco Aironet Wireless LAN Fundamentals (AWLF) course
Copyright © 2004, Cisco Systems, Inc.
Course Introduction
3
Learner Responsibilities This topic discusses the responsibilities of the learners.
Learner Responsibilities
Complete prerequisites Ask questions Provide feedback
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.0 #-6
To take full advantage of the information presented in this course, you must have completed the prerequisite requirements. In class, you are expected to participate in all lesson exercises and assessments. In addition, you are encouraged to ask any questions relevant to the course materials. If you have pertinent information or questions concerning future Cisco product releases and product features, please discuss these topics during breaks or after class. The instructor will answer your questions or direct you to an appropriate information source.
4
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
General Administration This topic lists the administrative issues for the course.
General Administration
Class-Related Sign-in sheet Course materials
Facilities-Related Site emergency procedures
Length and times
Rest rooms
Attire
Telephones/faxes Break and lunchroom locations
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.0 #-7
The instructor will discuss these administrative issues: Sign-in process Starting and anticipated ending times of each class day Class breaks and lunch facilities Appropriate attire during class Materials that you can expect to receive during class What to do in the event of an emergency Location of the rest rooms How to send and receive telephone and fax messages
Copyright © 2004, Cisco Systems, Inc.
Course Introduction
5
Course Flow This topic covers the suggested flow of the course materials.
Course Flow Day 1
A M
Course Introduction Impact of WLAN Applications and Design on a Site Survey Manual Site Survey Tools Manual Site Survey Utilities and Techniques
Lunch P M
Using the AirMagnet Site Survey Tool for a Manual Survey Assisted Site Survey Techniques WLAN Design Considerations Documentation
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.0 #-8
The schedule reflects the recommended structure for this course. This structure allows enough time for the instructor to present the course information. The exact timing of the subject materials depends on the pace of your specific class.
6
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Icons and Symbols This topic shows the Cisco icons and symbols used in this course.
Icons and Symbols Handheld Device
PC
Mobile Access Router
PC Card
Laptop
BBSM
AccessPoint
Wireless Bridge
Router
100BASE-T Hub Dual-Mode AccessPoint
Ethernet Client
Scanner
Small Hub (10BASE-T Hub)
Tablet
Wireless LAN Solution Engine
Wireless Connectivity © 2004 Cisco Systems, Inc. All rights reserved.
Copyright © 2004, Cisco Systems, Inc.
CAWSS 4.0 #-9
Course Introduction
7
Learner Introductions This is the point in the course where you introduce yourself.
Learner Introductions
Your name Your company Skills and knowledge Brief history Objective
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.0 #-10
Prepare to share the following information: Your name Your company If you have most or all of the prerequisite skills A profile of your experience What you would like to learn from this course
8
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Wireless Networking Overview This topic provides an overview of wireless networking.
Why Would I Want a Site Survey?
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.0 #-12
Many people think that there is a science behind installing a wireless LAN (WLAN). While there is certainly a lot of science behind the technology, performing a site survey may be thought of more as an art. As a WLAN site survey engineer, you will have to be knowledgeable about both the wireless equipment that you are installing and the wired equipment with which you may be interfacing. To overcome limitations that are presented by the facility, as well as by the equipment, a good site engineer will be able to think outside of the box. So why is a site survey important? Before installing WLAN access points, you need to know a number of things about the facility of your customer. A good site survey will help you determine the following: Feasibility of the desired coverage Radio frequency (RF) interference Wired connectivity limitations A site survey will allow the customer to properly install the WLAN and have consistent, reliable wireless access.
Copyright © 2004, Cisco Systems, Inc.
Course Introduction
9
Customer Assistance This topic identifies how a site survey will help the customer determine how many access points will be needed throughout a facility to provide the desired coverage.
Customer Assistance WL
RF
AN
Through put?
? ere Wh
erag e
H ow
m an y?
Cov
Wired Ave
.
ss le e r i W
© 2004 Cisco Systems, Inc. All rights reserved.
Bl
. vd
CAWSS 4.0 #-13
A site survey can also help determine the placement of those access points and detail the necessary information for installation. This class will provide you with lists of all the necessary tools, and the knowledge that is needed, to perform a site survey. While exposure to the tools and knowledge is certainly the place to start, it must be combined with experience. The more experienced the site survey engineer, the better the survey.
10
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
WLAN Topologies This topic identifies some of the topology information, standards, and components that a site survey engineer might need to be aware of when performing a site survey.
WLAN Topologies Limitations of the wired network Knowledge of wired LANs allows the following:
Creativity in your WLAN design
Superior design for the customer
Know wired and wireless alternatives
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.0 #-14
Sometimes the topology of the WLAN will be dictated by the layout of the wired LAN to which the WLAN will be connected. If wired connectivity is available only along one side of a 100,000 square-foot (9,290 square meters) warehouse, for example, the distance limitations of a Category 5 cable run (328 feet, or 100 m) may not be sufficient to reach the recommended location of the access point. This is where the site survey engineer will have to be creative. There are many possible solutions: a wireless hop using a repeater talking back to a wired access point, a repeater or a hub to extend the Category 5 cable run, or installation of a fiber link to provide connectivity on the other side of the warehouse. As a site survey engineer, you are responsible not only for finding the best locations for the access points but also for finding ways to connect the access points to the wired network.
Copyright © 2004, Cisco Systems, Inc.
Course Introduction
11
WLAN Topologies (Cont.) Understand wired networking products and their functionality Hubs Switches Routers Alternative media
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.0 #-15
It is therefore crucial that the engineer have an understanding of wired networks. This understanding should cover wired LAN topologies, standards, and components. The understanding of components must include the functionality of repeaters, hubs, switches, and routers. Attaching an access point to a hub has very different implications from attaching an access point to a switch, for example. By understanding the components, you will be able to design a WLAN that meets all specifications for the existing wired LAN topology. You must also be aware of the media being installed and be sure that the WLAN that you design will meet all requirements for that media type, as well as state and local building codes.
12
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Module 1
Impact of WLAN Applications and Design on a Site Survey Overview This module explores the various types of wireless LAN (WLAN) sites that site survey engineers need to survey in order to optimize coverage, and the special considerations that each site type presents.
Module Objectives Upon completing this module, you will be able to complete the objectives shown in the figure.
Objectives Obtain information necessary to perform the site survey Determine customer needs as part of preparation for designing a wireless LAN Identify the type of site survey to be performed prior to arrival at the customer site Describe the site situation and any possible obstacles that may impede the site survey
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-2
Module Outline The outline lists the components of this module.
Outline Overview WLAN Applications WLAN Design Retail Warehousing and Manufacturing Healthcare Hotels and Hospitality Hot Spots Education Offices Transportation Government Summary Review Questions © 2004 Cisco Systems, Inc. All rights reserved.
1-2
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
CAWSS 4.04-3
Copyright © 2004, Cisco Systems, Inc.
WLAN Applications As wireless technology continues to evolve, data rates and interference immunity are improving. These improvements make wireless a viable technology for use in most applications. This topic discusses WLAN applications.
WLAN Applications
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-4
As the acceptance of wireless technologies continues to grow, the advantages of a mobile workforce and a flexible network become more apparent to network managers.
Copyright © 2004, Cisco Systems, Inc.
Impact of WLAN Applications and Designs on a Site Survey
1-3
Be Prepared Come prepared to ask and answer questions. Instill a sense of confidence in the customer. Bring proper equipment.
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-5
Site survey engineers need to be aware of specific issues that surround many of the industries that require WLAN services. IT managers, upper management, or board members often want to discuss the implementation of wireless equipment in their facility. The customer wants to know that the WLAN installation will provide a reliable link to the network for wireless clients. Site survey engineers can expect that certain issues have already been resolved with a salesperson or site engineer prior to their arrival, but this is not always the case. Site survey engineers must be aware of all potential concerns so that they can present an informed and confident image when meeting with the customer. Site survey engineers who appear incompetent or misinformed may cause the survey or even the implementation to be cancelled altogether. Having the proper equipment (IEEE 802.11a, 802.11b, or 802.11g) on hand is one way that the site survey engineer can foster confidence.
1-4
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
RFYesterday and Today
Early adopters of RF technology Vertical markets Mobility
Today Vertical and horizontal markets Movability Standards and throughput
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-6
Early adopters of wireless technology were in vertical markets such as education and logistics. These users were more concerned with mobility than with standards or data throughput. Users today are moving into more horizontal markets where mobility may be less of a concern than interoperability and throughput. With the Cisco Aironet products, users do not have to sacrifice mobility and roaming to gain throughput and interoperability.
Copyright © 2004, Cisco Systems, Inc.
Impact of WLAN Applications and Designs on a Site Survey
1-5
5 GHz vs. 2.4 GHz Popular Choices Both technologies will work in these markets.
802.11b 802.11g 802.11a Hospitality
X
X
Manufacturing
X
X
Healthcare
X
X
X
Higher Education
X
X
X
Enterprise Office
X
X
X
Financial Institutions
X
X
Retail
X
X
Transportation
X
Warehousing
X
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-7
The figure here shows popular application choices for the various technologies. Depending on the application, all three technologies function very well in vertical markets. For instance, warehousing is generally record transaction updating, and therefore the data rate is not the highest concern; instead, the range is of chief interest. On the other hand, the patient areas of a hospital may require high data rates for file transfers of X-ray images. The following slides will address key issues that the site survey engineer should consider when deploying wireless technology. IEEE 802.11a uses a 5-GHz radio. 802.11b and 802.11g use 2.4-GHz radios.
1-6
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
WLAN Design There are several factors that are important in a WLAN design. This topic discusses some of those factors.
Wireless LAN Design Concerns
Client type and mobility Cards PCM, LMC, PCI Repeaters and workgroup bridges Third-party 802.11 devices Bar code scanners, telephony, Wi-Fi devices
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-8
One of the factors affecting WLAN design may be the particular type of client that the customer will be using. PC cards or embedded radios in laptops provide mobility to internal staff and easy connectivity for remote users when they are in the facility. Peripheral Component Interconnect (PCI) cards give users the freedom to occasionally move desktop PCs without having to worry about installing cable. A repeater or a workgroup bridge provides connectivity to remote users without standard leased lines or the need to run fiber. Some customers may want to use data collection terminals, while others want 802.11 phones. Most sites will use a combination of these options. A review of the specifications and compatibility information is needed from all devices to ensure functionality.
Copyright © 2004, Cisco Systems, Inc.
Impact of WLAN Applications and Designs on a Site Survey
1-7
Customer Applications Know what the customer needs from the wireless LAN E-mail and web users have different needs than a CAD developer Client-server Thin client
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-9
The site survey engineer must be aware of the applications that will be used in the wireless network. Someone who performs the occasional file transfer and checks e-mail has very different needs from someone using a computer-aided design (CAD) application across the network. Many offices today use a model with frequently used applications such as e-mail and internal ordering software loaded on each terminal. Other companies are moving to thin clients. They may have much greater bandwidth requirements. This type of setup requires a very reliable connection to the network, because an interruption of network service leaves the user helpless.
1-8
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Wireless LAN Design Pools of higher data rate coverage Stationary vs. mobile
54 Mbps
11 Mbps
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-10
In an environment where the PCs remain stationary most of the time, providing wireless connectivity is a fairly easy task. For installations of this type, users typically need pools of coverage and are not overly concerned with their link speed while moving. Many customers do not fully understand the equipment that will be installed or what to expect. Some people believe that it will be a full 11- or 54-Mbps link for every user. Some people question the reliability of the radio frequency (RF) link and intend to use the wireless link on a limited basis. The truth is that most users will fall somewhere between these two.
Copyright © 2004, Cisco Systems, Inc.
Impact of WLAN Applications and Designs on a Site Survey
1-9
Rate Shifting Survey performed at each data rate? Coverage cell for each rate mapped Higher rates shift to proper areas Lower rates overlap and frequency
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-11
There will be pools of coverage at each data rate. If the customer wants to provide certain areas with coverage at a specific data rate, multiple site surveys may be required. The Cisco Aironet Site Survey Utility surveys are at a given rate, and that rate does not shift. The higher data rate cells will need to be mapped out so they can be shifted to the proper areas. The lower data rate coverage cells will also need to be mapped out with an eye on the overlap of these cells and on frequency selection. An overlap of approximately 15 percent is required for smooth, reliable handoffs between access points. Before surveying, knowing how much throughput that the users require will help in determining where the access points will need to be placed.
1-10
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Copper vs. Wireless LAN Lower pricing on WLAN equipment Moving a terminal once makes RF the better solution Popularity increasing Consider future wireless LAN expansion while surveying
© 2004 Cisco Systems, Inc. All rights reserved.
$$$
CAWSS 4.04-12
Copper installations can still provide higher data rates, but price is no longer a factor. A WLAN can be installed for roughly the same price as a copper-based network, and provides many benefits in comparison to a wired network. As prices continue to come down on wireless products and throughput speeds continue to increase, wireless will continue to increase in popularity. The Wi-Fi Alliance interoperability certification program adds to this popularity. Future expandability is another possible reason for the popularity of wireless. If the customer wants to start by using a few wireless clients, and then increase the number once there is confidence about the reliability, it is possible to design a WLAN to accommodate this future expansion.
Copyright © 2004, Cisco Systems, Inc.
Impact of WLAN Applications and Designs on a Site Survey
1-11
Retail One of the early adopters of wireless technology was the retail industry. This topic discusses wireless in the retail industry.
Wireless in Retail Early users of wireless technology Wireless use for realtime applications Use of wireless technology for special events Use of WLANs for voice and paging Hot spots in retail stores
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-13
Data collection devices are extremely valuable tools for checking stock, receiving, and point of sale. Wireless data collection devices offer the retail industry real-time updates to their databases and the ability to place registers and printers throughout the store for special events (such as a sidewalk or tent sale) without having to worry about cabling. Recently there have been new kinds of wireless devices and services placed in the retail stores. The most popular are as follows: Wireless 802.11 phones Wireless kioskshelp customers to scan and validate prices Wireless multimedia stations or cartsprovide marketing and advertising information to retail customers Wi-Fi hot spotsWi-Fi access to the Internet in certain locations in the stores These wireless services and devices are additional overhead to the WLAN in the retail industry. They can be difficult to plan for because the wireless use is coming from the retail customers and not from the retail employees. Additional customer services may require a higher throughput RF technology such as 802.11a or 802.11g. In this case, a site survey would need to be performed to accommodate data collection devices using 802.11b and 802.11a or 802.11g devices.
1-12
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Wireless in Retail (Cont.) Uneven use of wireless during retail open and off hours Different wireless applications during different retail hours Heavy wireless LAN usage during inventory hours Heavy WLAN overhead by 802.11 voice devices Special coverage requirements on loading docs, back rooms and trailers, and hot spot usage © 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-14
Retail implementations often involve a large number of users sending data frequently. These same stores are likely to conduct their inventory at night. This situation can mean that there will be an uneven WLAN use during the normal store hours and night hours. During normal business hours, the WLAN may be taxed more with voice devices that place huge overhead on the 11-Mbps access points, because most voice devices operate in 2.4-GHz range. Typically, one Cisco access point can handle seven to eight concurrent voice conversations. If data collection terminals need to operate at the same time and in the same locations, the design and survey should be performed accordingly. When the inventory crew comes in at night, the customer expects that the WLAN will be able to handle the demand. The design needs to take several factors into consideration: how often inventory is conducted, how many data collection devices are used, the specific locations, and what the requirements are for their particular applications. It is also important to know if wireless phones will be used at the same time that the inventory is being conducted. It is also important to know if coverage on the loading docks or inside the trucks at the loading docks is required. Depending on the WLAN design, there may be enough RF coverage extending to the outside of the buildings to accommodate this need, but it is recommended that it be factored into the design.
Copyright © 2004, Cisco Systems, Inc.
Impact of WLAN Applications and Designs on a Site Survey
1-13
Wireless in Retail (Cont.) Most data collection devices do not support 802.11a or 802.11g yet. Some devices require only 2 to 11 Mbps. Will data collection devices be the only clients using WLAN? Survey for 11-Mbps coveragemost used on DC devices. Some devices can rate shift. © 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-15
If the customer intends to use data collection devices exclusively, this situation will change how the survey is performed. Most data collection devices today do not support 802.11a or 802.11g yet, and operate only at the 2- to 11-Mbps range. Most data collection applications do not require 54 Mbps. If the customer is using an 11-Mbps data collection device with no intention of adding other wireless clients or services that may operate in the range of 11- to 54-Mbps, then the site survey should be performed at 11 Mbps. All areas where the data collection devices will be used must have at least a 2-Mbps link if rate shifting is supported on the devices. Some data collection devices have the ability to rate shift from 54 to 48 to 36 to 24 to 18 to 11 to 5.5 to 2 to 1 Mbps for 802.11g or from 54 to 48 to 36 to 24 to 18 to 12 to 9 to 6 for 802.11a. It is important to know what the devices of the customer are, what abilities these devices have, and how the devices are to be used. Different data rates provide different coverage areas; the lower the data rate, the larger the coverage area will become, and the adjacent access point overlap may increase significantly.
1-14
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Wireless in Retail (Cont.) Multiple workers sending lots of information Needs of the application Evaluate the application
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-16
Retail sites may have areas with large numbers of very busy users, such as a receiving area. As equipment is unloaded from trailers, it is unboxed and bar codes are scanned in rapid succession, sending large packets containing a lot of data. If there are 20 to 30 users scanning bar codes and entering keystrokes in rapid succession, a single access point may not be enough. As an example, if all of the data collection devices are communicating at 11 Mbps, realistically, the access point is operating at only 11 Mbps. This is not to say that the access point is limited to 11 Mbps, but that there are no communications happening at data rates above 11 Mbps. While the 11-to-54-Mbps connection might be sufficient to handle the 20 to 30 users, the single 11-Mbps access point may be a bottleneck. The packet size of the application, the number of users, and the frequency with which the users will be transmitting data via the WLAN need to be assessed to determine if extra access points are needed in this area. If extra access points are needed, then access points must be configured on nonadjacent channels.
Copyright © 2004, Cisco Systems, Inc.
Impact of WLAN Applications and Designs on a Site Survey
1-15
Wireless in Retail (Cont.) Source of interference in retail Inventory items 2.4- and 5-GHz equipment Colocated stores using WLANs Colocated hot spots
Locate access points away from these items on the showroom floor. Consider different approaches to lower interference. © 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-17
Other concerns within the retail industry include the close proximity of the store to other RF devices. Some stores may stock and demo RF devices in their store, including satellite systems, baby monitors, or cordless phones. Many of these may be operating in 2.4-GHz range and some in the 5-GHz range. It is not recommended that access points be installed next to this type of equipment because they typically have a higher transmitter power. Some retail stores use internal cordless phone systems. Ideally, they should use a system that operates in a different RF spectrum. There are phones that operate at 900 MHz, 2.4 GHz, and 5 GHz. It is far less expensive to replace a few cordless phones than to try and design a WLAN around an existing phone system so that it does not interfere with it. Retail stores may also be located in malls or strip malls where there may be other users operating 2.4-GHz equipment or even a hot spot service provider operating on the same RF spectrum. The systems integrators and surrounding store managers can provide information about their systems or hot spot services. Site surveys should not be performed without this information. Optimally, the stores can separate their signals by channel, service set identifier (SSID), and so on.
1-16
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Mobile Users Wireless data collection means mobility. Coverage must be seamless.
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-18
Data collection users are also highly mobile users. That is the advantage of the wireless data collection device. It enables the end user to freely roam throughout the facility and scan items instead of having to carry the item to a scanner that is attached to a fixed terminal. Coverage must not have holes and must have enough overlap between access points to offer truly transparent roaming. If the application stops working, so does the user. Voice devices, unlike data collection devices, do not tolerate uneven or spotty coverage; the voice user demands uninterrupted and clear conversations; otherwise, customers will complain, and the system will not be used.
Copyright © 2004, Cisco Systems, Inc.
Impact of WLAN Applications and Designs on a Site Survey
1-17
Warehousing and Manufacturing Warehouse and manufacturing implementations present many obstacles. This topic discusses the various problems with warehouse and manufacturing implementations.
Warehousing Multiple users Large coverage areas Transaction-oriented applications Highly mobile users Varied wireless devices
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-19
Warehouse implementations present many of the same problems as the retail market. There may be a limited number of users during the day, but when a shipment comes in, or if multiple shipments come in at the same time, many or all users may be operating at the same time. Coverage areas are generally large, subject to a lot of multipath or RF interference because of concrete floors, metal roofing, and metal shelving. Cell size is more important than data rates because warehouse applications are generally transaction-driven with small packet sizes. Cell coverage overlap needs to be from 10 to 15 percent. The usage is not that high, but the users are highly mobile and must roam often. 2.4 GHz is almost always the choice. Diversity antennas are often useful in areas with higher multipath interference and utilization. Medium-gain antennas are generally the best solution. There is no way of determining the distance of a signal without knowing the type of inventory. Different types of stock will either absorb or reflect the radio frequency. Inventory that reflects an RF signal includes metal and lead-based paint. Inventory that absorbs an RF signal includes water, wood, plants and trees, paper and boxes, non-lead-based paint, pet food, and cat litter.
1-18
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Warehousing (Cont.) Talk with warehouse personnel about inventory levels. Consult more than one individual.
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-20
The site survey engineer should try to talk with personnel who work in the warehouse. A forklift driver may actually have a more accurate opinion of current stock levels. These levels can vary on a monthly, weekly, or daily basis depending upon the time of year and the business. The site survey engineer should also talk with the warehouse manager about when stock levels are at their highest and try to perform the site survey during this period. A warehouse at 50 percent stocking level has a very different RF footprint than what the same warehouse has at 100 percent. Making inquiries of numerous people will provide more accurate details about stock levels. The site survey engineer should talk with as many people as possible throughout the warehouse, inquiring about stock levels and periods of high usage. If this information gathering is not possible, the plan should compensate for the potential increase in stock. Otherwise, there should be a statement in the documentation that indemnifies the engineer if the physical layout of the site changes, to include stock levels.
Copyright © 2004, Cisco Systems, Inc.
Impact of WLAN Applications and Designs on a Site Survey
1-19
Warehousing (Cont.) Keep in mind while performing the survey: Exposure to the elements Freezers Weatherproof enclosures Shelving Antenna mounting Forklift paths
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-21
Warehouses or distribution centers are typically dirty and have maximum exposure to the elements. Here are a few questions to keep in mind while performing the survey: Will the access points need to be mounted in sealed boxes for protection? The environment will help determine if a sealed box is needed. Are there freezer areas (which are difficult to cover and hard on electrical equipment)? If the environment exceeds the limitations of the access point, will you need heated enclosures? How much clearance exists above the shelving? Will it be sufficient to mount an antenna? Or will a forklift or the inventory that the forklift is loading onto a top shelf crush the antenna? It is important to consider the performance of the various wireless devices. Warehouses often have wireless devices from several vendors or for different applications. The access point must be able to interface with the various devices and provide coverage for all.
1-20
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Manufacturing The applications are generally transactionoriented. Throughput is not the primary concern. Surveying should be done with the same concerns as warehousing.
CAWSS 4.04-22
© 2004 Cisco Systems, Inc. All rights reserved.
Manufacturing embraces WLAN solutions because it integrates very nicely into its just in time environment. WLAN devices are used for assembly line inventory accounting, RFcontrolled robots, quality control, network connectivity, and warehouse management. Forklifts can be equipped with wireless data collection devices, and handheld devices can be given to mobile workers. Manufacturing presents some issues that the site survey engineer must consider: High ceilings: Caution should be used when omnidirectional antennas are installed higher than 40 feet. This height will cause data collection devices underneath the antennas to lose the signal. Forklift paths: Forklifts can knock down equipment when they are moving stock. Machines: Conflicting frequencies can be generated by machines. Chain-link fence: This kind of fence blocks and grounds RF signals (such as in the tool room). Conveyor belts: The metal in the belts causes multipathing. Robots: Unmanned robots follow tracks in the floor to deliver products throughout the plant. Racking: Racking can affect WLAN devices depending on how the racks are oriented and what the racking holds. Unions: Respectfully find out what can and cannot be done by the site survey engineer. System redundancy: Hot Standby might need to be deployed to protect mission critical areas.
Copyright © 2004, Cisco Systems, Inc.
Impact of WLAN Applications and Designs on a Site Survey
1-21
Healthcare Healthcare site surveys are some of the most restricting, time-consuming, and difficult site surveys to be performed. The primary reason for this difficulty is that almost every hospital is a multistory building with numerous small rooms. This topic discusses site surveys in hospitals.
3-D Site Survey Watch out for the 2-D trap. Expect lots of access points. Make use of nonoverlapping channels. Look for trauma or X-ray rooms with lead-lined walls. Elevators represent potential dead zones.
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-23
Because of the multifloor configuration of many sites, the survey must be thought of as a threedimensional (3-D) survey. While marking site maps (which are two-dimensional), many engineers start to think of the survey as two-dimensional. The RF signal needs to be thought of as three-dimensional, covering not only the floor on which the access points are mounted but also the floors above and below. A hospital is a good example of a 3-D site survey. The need to think of a hospital site survey as 3-D is especially true in hospitals, because they typically require a large number of access points. Because there are only three nonoverlapping channels, special care needs to be taken when locating access points so that interference from other access points is eliminated as much as possible. Take advantage of the nonoverlapping channels when possible. Watch out for trauma and X-ray areas where the walls may be lead-lined. Also locate elevator shafts, which are usually colocated in hospitals and may be detrimental to the RF signal.
1-22
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Healthcare
Multiple floors Numerous rooms Numerous and quite diverse applications Multiple vendors of WLAN equipment
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-24
Certain applications such as portable X-ray and ultrasound devices may require a lot of bandwidth. These applications would require 802.11a or 802.11g data rates and are generally used in areas of the hospital that are the least friendly to RF signal propagation. These same areas of the hospital mostly have an overlay of RF networks. Those networks may be on different frequency bands but are generally using one of the three industrial, scientific, and medical (ISM) bands. Beyond this, there are a number of concerns that the RF devices may interfere with the wireless equipment, or vice versa, and hospital administrators will want assurances that there will not be interference. It is important to remember that portable hospital monitoring equipment may have embedded WLAN radios.
Copyright © 2004, Cisco Systems, Inc.
Impact of WLAN Applications and Designs on a Site Survey
1-23
Healthcare (Cont.) Testing performed by biomedical department Cisco Aironet Access Points Industrial, scientific, and medical FCC compliance
FCC safety Hospital equipment should be built to a standard to avoid RF interference © 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-25
Before any hospital floor space is surveyed, it is imperative that the site survey engineer determine that deploying 2.4-GHz and 5-GHz equipment will not interfere with life support equipment. This information is obtained by using the hospital biomedical department to certify that the equipment will not cause life-threatening problems. The 2.4-GHz and 5-GHz radios are Federal Communications Commission (FCC)-compliant and are part of the ISM unlicensed band.
1-24
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Healthcare (Cont.) Hospitals house sick peoplebe prepared to deal with this. Be sensitive to areas where you may not be wanted or allowed. Do not abuse privileges.
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-26
Hospital surveys also require engineers with a certain amount of mettle. It is not unheard of to have to survey the intensive care unit, infant intensive care unit, birthing unit, surgery unit, burn victim unit, morgue, emergency room, or trauma unit. The sight of patients in a condition that requires them to be in one of these units sometimes has a very profound effect on individuals. The engineer needs to be able to handle all of this with grace. More than one engineer has been caught in the trauma unit when a critically injured patient is being wheeled in. Most hospitals cannot afford to have an individual escort the engineer all day while they perform the survey. Engineers are usually given a visitor badge and a tour, where they are shown specific areas where they will not be allowed without an escort, if at all. In the surgery area of the hospital, the engineer may be required to wear a gown to survey the area. Usually, engineers are not allowed in the psychiatric ward or the criminal ward without a security escort.
Copyright © 2004, Cisco Systems, Inc.
Impact of WLAN Applications and Designs on a Site Survey
1-25
Hotels and Hospitality Hotels are much like hospitals in their building construction and configuration (multifloor with many rooms). Hotels have started using WLANs to support data collection devices for taking inventory of things such as minibars. However, with the popularity of the Internet and the demand for Internet connectivity, WLANs are being installed into more and more hotels to provide Internet connectivity for hotel guests. This topic discusses the specific site survey concerns presented by hotels.
Hotels and Hospitality Multifloor construction Numerous rooms
Hotel
Throughput Fewer users per access point Multiple building materials
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-27
Beyond requiring the engineer to look at the survey three-dimensionally, hotels present such concerns as data rates and throughput, and security. The high number of walls (separating guest rooms) decreases the range of access points and thus increases the need for more access points. Hotels want to offer their guests fast, reliable Internet access, which means fewer users per access point. In addition, hotels historically have a lower density as rooms geographically distribute users fairly well, which helps with the placement of access points.
1-26
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Hotels and Hospitality (Cont.) Physical security Network security Billing Aesthetics Older hotel buildings Hard-cap ceiling Poured concrete walls
Newer hotels have drop-tile ceilings
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-28
Most business travelers want to know that the data that they are sending is secure, and the hotel wants to know that not just anyone with an 802.11 card can access its network. Hotels often house restaurants, and retail and convention areas, which makes them fairly public places and thus susceptible to theft and vandalism. Proper securing of the access points to ceilings or walls, in addition to hiding them above the ceiling, are good practices. One solution to the security issue is Wired Equivalent Privacy (WEP) encryption. Cisco Aironet recommends using at least 128 bits. Other methods of security available with Cisco Aironet include a RADIUS server or Building Broadband Service Manager (BBSM). The overhead that WEP adds is minimal (about 3 percent). This relative lack of overhead means that there is no need to survey using WEP keys. If the customer decides to implement WEP during installation, it will have no effect on the survey. Another solution is Cisco Lightweight Extensible Authentication Protocol (LEAP) authentication (based on 802.1x standards). Just as with WEP, there is no need to implement LEAP during the survey. These two solutions do, however, require additional directions to customers and possible back-end work on the part of IT (creating new user accounts and so on) or both. Hotels will also have many of the same concerns as hospitals regarding aesthetics. Depending on the age of the hotel, building construction may become a factor. Newer hotels will have drop-tile ceilings in hallways but rarely in guest rooms. Older hotels will often have hard-cap ceilings. These are ceilings that are poured concrete. There is no real, effective way to run cable across a hard-cap ceiling. Keep this fact in mind when you are deciding where to mount access points. Older hotels may also have walls of poured concrete instead of Sheetrock. This situation presents the same problems as hard-cap ceilings. A solution is to use Cisco LRE (Long-Reach Ethernet) over the existing phone lines; Cisco LRE makes use of the phone lines for high-speed Ethernet.
Copyright © 2004, Cisco Systems, Inc.
Impact of WLAN Applications and Designs on a Site Survey
1-27
Hotels and Hospitality (Cont.) Possible interference with hotel infrastructure wireless Cleaning services, maintenance, security
Possible multiple providers in separate locations of hotel Rooms, convention center, retail areas
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-29
Wireless has become increasingly popular as a means of streamlining hotel operations, for everything from guest services (check-in, concierge) to house cleaning and maintenance. Handheld devices and IP phones require their own infrastructure. If the public access provider is willing, the use of VLANs can allow single access points to support both public and private usage. Otherwise, overlay networks are required. Hotels are no longer simply places for travelers to spend the night. Increasingly, they have everything that travelers need during their stay: convention and conference services, retail shops, and, of course, restaurants. These locations may have their own contracts and providers, causing possible interference between networks.
1-28
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Hotels and Hospitality (Cont.)
Hotel conference centers Sporadic usage High density for key shows Differing security requirements for individual shows
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-30
By their very definition, convention and conference centers do not have continual usage and often provide fewer access points. When the convention or conference is in use, however, there is the potential for a huge number of users in a small area, a situation that requires a high number of access points providing high throughput per user. The convention center network usually needs to be isolated and available for numerous changes and additions. Each incoming convention requires different types of security (WEP, 802.1x, open, and so on), as well as front-end servers and other services available to attendees. This location should not be connected to the hotel network because it could provide a source for viruses and bring instability to the hotel network.
Copyright © 2004, Cisco Systems, Inc.
Impact of WLAN Applications and Designs on a Site Survey
1-29
Hot Spots The buzzword hot spot refers to booming installations of 802.11 wireless access points in public areas. These hot spots are targeted at the business community and people on the go who see the value in staying connected. This topic discusses hot spots.
Hot Spots Hot spot provider Subscribers Survey not so necessary Effective range 300-500 feet Generic network
Public areas Coffee shops, restaurants, hotels Airports, convention centers, Marinas, parks
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-31
Hot spot providers need to offer high-speed throughput and transparent use of Internet subscriptions to satisfy the paying public. Some of these locations can be easily covered by one access point (300 to 500 feet, or .09144 to .1524 km). Coffee shops, airports, and other locations will require a more elaborate configuration. Analysis Research estimates that by the year 2007, there will be 40 million people that will use hot spot locations worldwide. With the popular use of handheld devices and new laptops being shipped Wi-Fi ready, the growth is well on its way. According to the research firm IDC, the number of wireless subscribers in the United States will increase at a whopping compound annual growth rate (CAGR) of 73 percent, from approximately 5 million in 2000 to more than 84 million in 2005.
1-30
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Hot Spots (Cont.) New and emerging technologies and standards 802.11a, b, g Appropriately plan for users to have different types of technology cards. Increased number of hot spots means increased interference, possible overlap.
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-32
Hot spots are designed to cater to anyone who wishes to obtain access to the Internet. With the emergence of 802.11a and 802.11g, combined with 802.11b, providers must offer additional capabilities. Cisco access points provide for all three technologies via a single access point through the use of multiple radios per access point; however, each radio has a differing range and thus requires site surveys for each technology. With the increasing demand for public access, a large number of locations are offering hot spot services. These areas might be located in close geographic proximity, and thus the potential for interference increases. Pay close attention to who is in close proximity and their possible interference.
Copyright © 2004, Cisco Systems, Inc.
Impact of WLAN Applications and Designs on a Site Survey
1-31
Education The primary concern when you are implementing a WLAN in an educational facility is the students. More and more WLANs are being installed in grade schools, middle schools, and high schools. Students at this age have a tendency to be curious and sometimes destructive. This topic discusses the factors involved in an educational site survey.
Education Children can be Curious Destructive Antennas and access points should be hidden or enclosed to avoid damage.
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-33
An antenna mounted to the ceiling in a hallway will likely not stay mounted for long. Access points have flashing lights that seem to draw in curious children. Educational facilities, more so than any other implementation, must have the equipment installed in the most inconspicuous manner possible. This level of precaution is the only way to ensure that the equipment will be safe. However, there are other security mechanisms that can help with the situation. Using National Electrical Manufacturers Association (NEMA) enclosures with enclosed locks can help prevent tampering or theft. You can use these enclosures in locations where access points cannot be hidden easily or in a truly high-risk area.
1-32
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Education (Cont.) New technologies requiring schools to plan for new surveys New applications (IP telephony and surveillance) requiring increased access point density
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-34
Wireless technology provides more than just data access for laptops; it can also be used for IP telephony or surveillance cameras. These new technologies use additional bandwidth that requires increased density of access points or use of newer technologies (802.11g and 802.11a). New site surveys may need to be conducted on locations that have already deployed wireless technology that was designed exclusively for limited data access.
Copyright © 2004, Cisco Systems, Inc.
Impact of WLAN Applications and Designs on a Site Survey
1-33
Offices The wireless office and small office, home office (SOHO) markets are some of the most quickly emerging markets. This topic discusses the special concerns that the site engineer must address when surveying the wireless office.
Small Office Quickly emerging market New solutions being developed
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-35
Many vendors are racing to put out RF products for the home. In the meantime, many customers are trying to find creative ways to use industrial products in the SOHO environment. Most small offices will not require a site survey. If the office has fewer than four computers, then a more economical solution might be an ad hoc network. However, using an access point ensures a central point for connectivity and troubleshooting. Some customers may want a site survey anyway, looking ahead to future growth and expansion. In such instances, a single access point that may be moved or connected via a wireless repeater can be set up. Small offices are often located near retail properties that have other small offices. Those offices may also be using WLAN solutions, so there is the potential of overlapping cells between different businesses. Channels should be selected with either low use or with a signal strength that is adequate but that does not send the signal far outside the required coverage area. Part of securing a network is making it less visible. Lowering the transmit (Tx) power to just what is needed to provide coverage inside the office area makes the network more secure from outside the office. A remote wireless office can also be monitored and surveyed from a centralized management system like the CiscoWorks 1105 Wireless LAN Solution Engine (WLSE).
1-34
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Enterprise Office 2.4 GHz
5 GHz
4 Access Points
16 Access Points 54 Cubes4 Conference Rooms
54 Cubes4 Conference Rooms Conference Room
Conference Room
Conference Room
Conference Room
120 Feet
120 Feet
Conference Room
Reception
95 Feet
© 2004 Cisco Systems, Inc. All rights reserved.
Conference Room
Conference Room
Reception
Conference Room
95 Feet
CAWSS 4.04-36
The wireless office presents a tremendous opportunity today. On the average, enterprise offices change configurations at least twice a year. This change may involve new additions or expansions, or it may involve relocating individuals or entire departments. In either case, a WLAN makes these types of moves much easier. Whether the employee is using a desktop or a laptop, all that needs to be done is to move the PC and ensure that it is within a WLAN coverage area. This ease of use means countless hours saved by the IT department, and money saved on cabling or recabling expenses. WLAN equipment with data rates of up to 54 Mbps are likely to be popular in an enterprise solution, allowing more users and better throughput on a per-access-point basis. The 54-Mbps coverage area will be approximately one-quarter of the 11-Mbps cell size, meaning more access points to cover the same area. Also, 5-GHz equipment will not able to penetrate through walls as well as 2.4-GHz equipment will. Tools like Cisco Works WLSE can be extremely helpful for setting up access points in a new office or changing the configuration of access points in an office where a WLAN already exists but needs to be upgraded. If there are a variety of client types and applications, it is a good idea to use a walkabout survey with each client. The walkabout with various clients ensures that all clients will receive adequate coverage. The number of access points that are required to provide coverage will vary based on the radio band used, the Tx and receive (Rx) characteristics of the clients, the Tx and Rx configurations of the access points, and the types of cable and antennas that are used with the access points.
Copyright © 2004, Cisco Systems, Inc.
Impact of WLAN Applications and Designs on a Site Survey
1-35
Transportation Transportation surveys for sites such as rail yards and airports present a variety of situations and obstacles that site survey engineers must take into consideration. This topic discusses those situations.
Transportation Rail Yards Rail cars Made of wood and metal Transport a variety of cargo Large Narrow pathways between tracks
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-37
Rail yards can be difficult to survey and install for many reasons. The cars themselves are very large and constructed of wood or metal. Cars may be filled with a variety of materials that can limit the signal, such as livestock, wood, metals, or perishable materials in wooden or cardboard boxes. Inside the yard, tall rail cars that are located on parallel tracks form narrow pathways for the signal. Yagi antennas mounted on poles above the cars at either end of the yard are often the best solution to this situation, allowing the RF signal to shoot down the narrow pathways.
1-36
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Transportation (Cont.) Airports Easy two-dimensional coverage Typically open area Long open pathways
Post-9/11 issues Rules and regulations Baggage ramp area
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-38
Airports are usually very wide, open areas, with long, open pathways. This type of coverage makes the survey simpler for the engineer because the survey becomes two-dimensional. Because of security restrictions after the 9/11 terrorist incident, the engineer should check with local airport authorities about obtaining the proper clearance. This clearance may require an FBI background check. One difficulty in covering airports is when coverage is needed outside the facility, for example, in the outdoor baggage areas. Much like warehouse installations, these access points may be subject to extreme weather conditions and may require weatherproof enclosures. Another situation that the site survey engineer can encounter is that there may already be wireless gear installed throughout the airport, making channel selection difficult. WLAN products are used in many airports today by the airlines, as well as by service providers that are enabling business travelers to connect to the Internet wirelessly while waiting for flights. The projected wireless application must be in accordance with FAA regulations as well as any other governing guidelines for the specific airport.
Copyright © 2004, Cisco Systems, Inc.
Impact of WLAN Applications and Designs on a Site Survey
1-37
Transportation (Cont.) High traffic areas Equipment can be damaged or stolen if not put away properly
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-39
Another difficulty in surveying airports is the high traffic there. While people are certainly used to seeing work crews roaming throughout an airport, it does not mean that they will be cautious around an engineer during a site survey. Proper care of the site survey materials is important to prevent theft or injury. A misplaced cable that a traveler trips over could result in a lawsuit. In addition, today more than ever, airports are concerned with security. Access points and battery packs, with their flashing lights and wires wrapped around them, can easily be mistaken for some sort of destructive device. It is important that the site survey engineer meet with all necessary security personnel before starting the survey.
1-38
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Government Government facilities, like airports, are at a heightened level of security, and care should be taken that the site survey equipment is not mistaken for something other than site survey equipment. There are facilities of every type at government locations, particularly military facilities. Many military bases may have one of every facility already discussed in this module. This topic discusses government site survey issues.
Government Secure facilities Variety of facilities Security clearance Equipment checklists
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-40
Security clearances or escorts will likely be required as part of a government site survey. The vehicle of the site survey engineer may be subject to a search upon entering or leaving the facility. An equipment list may be required, and the equipment may be checked on a daily basis. Equipment lists and proper documentation will be required when entering foreign countries to perform site surveys. Each country may have different standards and require different documentation for entering the country with site survey equipment. The site survey engineer must be prepared and have the proper paperwork to save time, trouble, and potentially the expense of having the equipment bonded or retained by the customs department.
Copyright © 2004, Cisco Systems, Inc.
Impact of WLAN Applications and Designs on a Site Survey
1-39
Key Requirements for Metropolitan Mobile Networks Need real-time access to intelligence information for effective resource management Need for voice, video, and data communications to support mission-critical situations within the community Need to enable mobile networks to download and upload data
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-41
The government implementation addresses the need for real-time access to people and resources in the field. Cisco Metropolitan Mobile Networks are driven by the need for voice, video, and data communications, as well as the need to enable mobile networks to download and upload data.
1-40
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Mobile Devices Improve Communication Processes Extend the reach of the network to any location in a secure and manageable manner Provide the tools that are needed to work remotely Send field information in real time
Public Sector Agency Gains
Provide access to agency services from the field
Increase employee productivity and response time while at remote locations © 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-42
Applications are the driving force for mobile networks to be used. Public agencies need to share infrastructure and save money.
Copyright © 2004, Cisco Systems, Inc.
Impact of WLAN Applications and Designs on a Site Survey
1-41
Community Residential Deployment 802.11b / 11 Mbps
802.11a / 54 Mbps
Service Provider 802.11b / 11 Mbps
Service Provider / Tower :
Cisco Aironet 1400 Series Bridge
Tower / Residential Houses:
Cisco Aironet 350 Series Bridge
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-43
There are many examples of how a service provider can supply a neighborhood with wireless coverage using a combination of multiple technologies.
1-42
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Local Government Deployment Fire Station Police Station
City Hall Hospital
City Agency Vehicle
On Buildings:
Cisco Aironet 350 and 1400 Series Bridges
On Vehicles:
BR350, 3220 Mobile Access Router
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-44
This is an example of how a mobile network can use many wireless products.
Copyright © 2004, Cisco Systems, Inc.
Impact of WLAN Applications and Designs on a Site Survey
1-43
Summary This section summarizes the key points discussed in this module.
Summary
Information needed to perform the site survey Customer application needs Type of site survey to be performed Obstacles and situations that may be present while you are performing a site survey
© 2004 Cisco Systems, Inc. All rights reserved.
1-44
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
CAWSS 4.04-45
Copyright © 2004, Cisco Systems, Inc.
Review Questions Use the practice items here to review what you have learned in this lesson.
Review Questions What are some of the items that retail stores stock that may interfere with WLAN equipment? What are some of the equipment concerns that are involved with surveying hospitals? How can a WLAN improve productivity in an office? What type of inventory absorbs an RF signal? IEEE 802.11a and 802.11b and g use what type of radio frequencies?
© 2004 Cisco Systems, Inc. All rights reserved.
Copyright © 2004, Cisco Systems, Inc.
CAWSS 4.04-46
Impact of WLAN Applications and Designs on a Site Survey
1-45
1-46
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Module 2
Manual Site Survey Tools Overview This module explores the types of equipment that a site survey engineer should always have as part of a site survey kit.
Module Objectives Upon completing this module, you will be able to complete the objectives shown in the figure.
Module Objectives
Identify the equipment that is needed to build a site survey kit Determine the importance of items that are included in the site survey kit
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-2
Module Outline The outline lists the components of this module.
Module Outline
Overview Access Point Selection Site Survey Equipment Summary Review Questions
© 2004 Cisco Systems, Inc. All rights reserved.
2-2
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
CAWSS 4.04-3
Copyright © 2004, Cisco Systems, Inc.
Access Point Selection Different types of sites require different access points. This topic discusses access point selection.
Access Point Selection 2.4-GHz access points Supporting remote antennas Reverse Polarity Threaded Naval Connector (RP-TNC) 1200 Series Access Point (2.4 GHz) Supporting only internal antennas 1100 Series Access Point
5-GHz access points 1200 Series with 5-GHz module Attached antenna only
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-4
The site survey engineer should always carry more than one device of each model that is needed in the survey. Many engineers have had a mishap with their only device, resulting in downtime during the survey. An extra access point or client device allows the survey to continue without having to wait for a spare to be shipped. Access points that have radio frequency (RF) connectors allow the site survey engineer the option of using a variety of antennas to overcome coverage problems or mounting issues. The 2.4-GHz antenna ports of the Cisco Aironet 1200 Series Access Point have reverse-polarity threaded naval connectors (RP-TNCs). The Cisco Aironet 1100 Series Access Point does not have an RP-TNC, which limits the site survey engineer to a diversity 2.2 decibels over isotropic (dBi) internal antenna. The 1200 Series Access Point has a 5-GHz module that serves as the 5-GHz CardBus radio and the antenna. Because of Federal Communications Commission (FCC) requirements, the 5-GHz antenna module offers two options, a 6-dBi patch mode and a 5-dBi omnidirectional mode. At some point in the future there may be available a version of a 5-GHz RF module for the 1200 Series Access Point that does not support the Unlicensed National Information Infrastructure (UNII) 1 band, and therefore may be supplied with remote antenna capability.
Copyright © 2004, Cisco Systems, Inc.
Manual Site Survey Tools
2-3
Survey with Correct Equipment If the customer is purchasing a 1200 Series Access Point, then survey with a 1200 Series Access Point. Analyze the client devices that are intended to be used in the site. Many clients support lower transmit power levels than the Cisco cards. Choose a power setting on the client side that simulates the lowest-powered device that will be used.
Use the same technology that the customer has specified for an application (802.11a, 802.11b, 802.11g). It may be beneficial to use an 802.11g access point for all 2.4-GHz surveys. The device will support both 802.11b and 802.11g.
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-5
Before you begin surveying, it is important to understand what the customer applications will require for bandwidth and range. This information may make a difference in what technology will work best for the site. Use the access point the supports the required technology. For 802.11b, the site engineer can use an 802.11g access point and set the data rates to the 802.11b rates only. This setup allows there to be one less device to maintain and carry. For the client side, be certain that the power level is set appropriately. Many devices do not support the 100 milliwatts (mW) that Cisco products support for 802.11b. The engineer should review the listed client devices from the presite survey report, research to determine the power levels of these devices, and then select a level that simulates the devices with the lower power levels.
2-4
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Site Survey Equipment There are several pieces of equipment that the engineer should bring on any site survey. This topic discusses the site survey equipment.
Client Cards
Client devices PC cards Embedded laptop radios LM cards
MMCX cable connectors
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-6
A survey kit should contain at least one of each type of client device. This kit should include a laptop with an embedded radio, although the performance may be different than with a CardBus card due to antenna variations. The device that represents the worst case performance should be selected. In most cases this device will be either the laptop with an embedded radio or a device with a CardBus card. Unlike the CardBus or internal radio, the Peripheral Component Interconnect (PCI) client device and the workgroup bridge offer an antenna that can be placed in an optimum location for the device. The engineer should survey with the device that the client intends to use. If the client is planning on mounting a terminal inside of a crane and attaching it via a LAN Module (LM) card with a 5.2-dBi antenna, then the engineer should survey with the same. It may also be beneficial to include the adapter for the LAN Module Controller (LMC) card (MMCXRP-TNC) and an LMC card in the survey kit. The engineer will be able to attach a variety of antennas to the LMC card and emulate the installation that is desired by the client.
Copyright © 2004, Cisco Systems, Inc.
Manual Site Survey Tools
2-5
Antennas Two of every antenna that you may have to use Diversity Availability of antennas
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-7
There is no single antenna that is perfect for all applications, and, therefore, a variety of antennas are offered. The customer, in many cases, dictates antenna choice and placement. A customer may not want the antenna to be visible, or may wish it be located in a high-traffic area. By carrying a variety of antennas, the site survey engineer is prepared for any situation. The minimum collection of antennas should include (but is not limited to) the following: 2.2-dBi rubber dipole antenna (AIR-ANT4941) 2.2-dBi diversity omnidirectional ceiling-mounted antenna (AIR-ANT3351) 5.2-dBi mast-mounted antenna (AIR-ANT2506) 5.2-dBi omnidirectional ceiling-mounted antenna (AIR-ANT1728) 5.2-dBi diversity omnidirectional pillar-mounted antenna (AIR-ANT3213) 6.0-dBi diversity patch wall-mounted antenna (AIR-ANT2012) 8.5-dBi hemispherical patch antenna (AIR-ANT3549) 10.0-dBi Yagi mast-mounted antenna (AIR-ANT2410Y-R) 13.5-dBi Yagi mast-mounted antenna (AIR-ANT1949) An engineer who knows that a special antenna will be required for a particular site survey should be certain to include that antenna in the kit for that specific site. Site survey engineers should always survey with the antenna that the client intends to use. If using diversity antennas, the engineer will need to carry two of every antenna unless the antenna is especially made to support diversity and contains two antennas. For more antenna options, refer to the Cisco Aironet Antenna Reference Guide, which you can find at this URL: http://www.cisco.com/en/US/products/hw/wireless/ps469/products_data_sheet09186a0080088 83b.html. Note
2-6
Do not use a different antenna and attempt to estimate the coverage. The site survey is being performed to take the guesswork out of the installation.
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Antenna Cable Loss Try to use the cable that is supplied with the antenna, avoiding long cable runs when possible.
LMR400
Cisco offers these cables:
LMR600
LMR400-style cables 20 and 50 feet Total loss of 1.3 and 3.4 dB, respectively LMR600-style cables 100 and 150 feet Total loss of 4.4 and 6.6 dB, respectively
© 2004 Cisco Systems, Inc. All rights reserved.
Cable Type
2.4 GHz 5.8 GHz Loss Loss (db/100 feet) (db/100 feet)
LMR400
6.6
10.8
LMR600
4.4
7.25
CAWSS 4.04-8
RF energy is carried between the antennas and the radio equipment through a coaxial cable. An antenna cable introduces signal loss in the antenna system for both the transmitter and receiver. Loss of signal strength is directly proportionate to the length of the cable segment. As the diameter of the cable increases, signal loss is decreased, but at a much higher purchase cost. As signal frequency increases (higher-numbered channel), signal loss increases. To reduce signal loss, minimize the cable length and use only low-loss or ultralow-loss antenna cable to connect radio devices to antennas.
Copyright © 2004, Cisco Systems, Inc.
Manual Site Survey Tools
2-7
Mounting Tools Mounting bracket Mounting solutions Bright color tape Velcro Beam clamps Zip ties
Secure the access point!
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-9
The site survey engineer should always carry an access point mounting bracket (when available). The kit should also contain various mounting solutions for the bracket (beam clamps, C-clamps), as well as mounting brackets for each antenna (when available). Zip ties, duct tape, bailing wire, electrical tape, two-sided tape, Velcro, and paper clips are common components in the kit of a good engineer. During a survey there is no bad mounting solution except the solution that does not properly secure the access point, battery pack, and antenna. A bad mount not only might damage the equipment but risks injuring the engineer or others when the equipment comes crashing down.
2-8
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Battery Pack and Cables
Battery Pack Charger Cables Serial or RJ-45 to DB9 rollover cable RP-TNC assembly
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-10
Access points require power to operate. There will not always be power available nearby when you are performing a site survey. A good battery pack will last for at least 8 hours, allowing the engineer to survey all day without having to recharge. Also recommended is a fast charger for the site survey tool. If a laptop is used, spare battery packs that can be charged separately from the laptop are always recommended. Wireless PC cards require a constant source of power while you are surveying and may reduce battery life to less than two hours.
Copyright © 2004, Cisco Systems, Inc.
Manual Site Survey Tools
2-9
Access Point Markers Mark access point and antenna locations Bright colors Durable but easily removed
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-11
Once the access point placement is determined, it will be necessary to mark the location. Location markers should be very bright and resistant to dust, grease, and water. Surveyor tape works very well and comes in a variety of bright colors. Brightly colored signs allow the engineer not only to mark the location of an access point but to give some detail as to how the access point is to be configured and mounted, and provide a point of reference to anyone reading the site survey report. Markers should be sturdy but temporary.
2-10
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Measuring Devices Measuring wheel (horizontal distances) Height measurement Rope marked in 10-foot or 3-meter increments (vertical distances)
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-12
In order to provide the customer with the details that are needed to bid for the installation, the engineer will have to provide many measurements in the site survey report. And these measurements need to be as accurate as possible. If the engineer guesses the Cat 5 cable run to be 300 feet (91 meters), and it turns out to be 380 feet (116 meters), the customer will be very unsatisfied. The kit should include a measuring wheel (for measuring cable distances). Many engineers include more advanced equipment, such as laser measuring devices and range finders. These are viable options, but a measuring wheel is usually adequate. For measuring vertical distances, a rope marked in 10-foot (3-meter) increments allows the engineer to accurately judge distances from floor to ceiling. (Counting floor tiles or ceiling tiles is not a good measurement of distance.)
Copyright © 2004, Cisco Systems, Inc.
Manual Site Survey Tools
2-11
Digital Camera Easiest way to document unusual situations Need to photograph antenna mounting locations and methods
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-13
It is always best to photograph any unusual situations that you find while performing site surveys. These situations may consist of moving or retractable walls, shelving locations, overhead cranes, and so on. All antenna mounting methods and locations should be photographed and incorporated into the site survey document because the surveyor may not do the actual installation work.
2-12
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Travel Case Portable travel case Sufficiently padded Checkable as luggage
Quick deployment
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-14
The most important part of a site survey is the site survey kit. No matter how talented the engineer may be, it is impossible to perform a site survey without the proper tools. It is recommended that a site survey kit be a portable unit. For ease of use, a hard plastic case that rolls and can be checked as luggage is the best and most common package. Often site surveys are requested on very short notice. With the ability to carry the case in the trunk or back seat of a car, and check it as luggage, the engineer can travel with the equipment. This ease of use solves the problem of the kit being lost or detained when shipped. It also allows for quick deployment of an engineer.
Copyright © 2004, Cisco Systems, Inc.
Manual Site Survey Tools
2-13
Cisco Aironet Site Survey Kit Cisco Aironet In-Building Site Survey Kit Airline-approved travel case Custom-cut foam inserts
Inventory includes the following: Access point with 2 RP-TNC connectors 2.4 GHz 5-GHz radio module (optional)
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-15
TerraWave Solutions offers a Cisco Aironet In-Building Site Survey Kit. Designed to provide system engineers with cutting-edge survey capabilities, the In-Building Site Survey Kit is loaded with accessories crucial to performing professional site surveys. This airline-approved travel case has custom-cut foam inserts to protect and organize each individual item. The Cisco Aironet In-Building Site Survey Kit weighs less than 65 pounds, and has wheels and a handle that make it easy to travel with to any customer site. The kit contains the following: Access point with two RP-TNC connectors 2.4 GHz 5-GHz radio module (optional)
2-14
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Cisco Aironet Site Survey Kit (Cont.) PC card adapter with integrated antenna 802.11b 11 Mbps (2.4 GHz) Optional 802.11a 54 Mbps (5 GHz) 2.2-dBi dipole antenna 2-dBi diversity omnidirectional ceiling-mounted antenna 6.5-dBi diversity patch wallmount antenna
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-16
More Cisco Aironet In-Building Site Survey Kit contents are as follows: PC card adapter with integrated antenna 802.11b11 Mbps (2.4 GHz) 802.11a54 Mbps (5 GHz) (optional) Four 2.2-dBi rubber dipole antennas Two 2-dBi diversity omnidirectional ceiling-mounted antennas Two 6.5-dBi diversity patch wall-mounted antennas Contact your nearest Cisco representative for complete details.
Copyright © 2004, Cisco Systems, Inc.
Manual Site Survey Tools
2-15
Summary This topic summarizes the key points discussed in this module.
Summary Access point selection considerations Equipment in the site survey kit
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-17
A site survey engineer needs to be prepared with the right equipment. Asking the customer questions about the survey provides an insight as to whether or not the engineer may need something extra. The site survey engineer must identify potential obstacles before beginning the site survey.
2-16
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Review Questions Use the practice questions here to review what you have learned in this module.
Review Questions What items should be included in your site survey kit? Why is it a good idea to have several different types of antennas included in your kit? Why is a digital camera needed in your kit? What types of mounting solutions are included in your kit?
© 2004 Cisco Systems, Inc. All rights reserved.
Copyright © 2004, Cisco Systems, Inc.
CAWSS 4.04-18
Manual Site Survey Tools
2-17
2-18
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Module 3
Manual Site Survey Utilities and Techniques Overview This module explores potential situations and obstacles that a site survey engineer may encounter. It also discusses the many software tools available to aid the site survey engineer.
Module Objectives Upon completing this module, you will be able to complete the objectives shown in the figure.
Module Objectives
Identify potential situations that you may face while performing a site survey Identify potential obstacles that you may face while performing a site survey Identify the software tools that can be used for a site survey Identify the limitations of cell boundaries
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-2
Module Outline The outline lists the components of this module.
Module Outline Overview Preparation Indoor Site Survey Concepts Software Tools Summary Review Questions
© 2004 Cisco Systems, Inc. All rights reserved.
3-2
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
CAWSS 4.04-3
Copyright © 2004, Cisco Systems, Inc.
Preparation After the engineer has discovered possible trouble areas, examined the application needs of the customer, and talked with the IT staff concerning their network, it is time to start the survey. This topic discusses the preparations that the site survey engineer should make just before the survey begins.
Preparation
Prior to arrival Ensure equipment is operational Configure equipment (if possible) Determine if lift is needed Determine who will provide the lift Make sure that batteries are fully charged
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-4
Prior to arriving on site, the engineer should ensure that all of the equipment is operational. The equipment should be configured and ready to survey before arrival at the customer site, including charging all batteries and battery packs the night before. The engineer should call ahead and find out if a lift will be needed to reach the ceiling, and if so, whether the customer will provide the lift or if the engineer should provide the lift. The engineer should also have a license to operate the lift if necessary.
Copyright © 2004, Cisco Systems, Inc.
Manual Site Survey Utilities and Techniques
3-3
Indoor Site Survey Concepts While every site will present different challenges to the engineer, there are a few general rules that affect an indoor site survey. This topic discusses those rules.
Materials Affecting RF Range
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-5
Metal film on glass, leaded glass, steel-studded walls, cement floors, walls with steel reinforcement, foil-backed insulated walls, stairwells, and elevator shafts are typical construction methods and materials that affect range. There is no way of determining the distance that a signal will travel without a survey. Inventory: Different types of inventory affect radio frequency (RF) range, particularly those with high steel or water content. Some items to watch for are cardboard boxes, pet food, paint, petroleum products, engine parts, and so on. Levels of inventory: It is important that the engineer perform the site survey at peak inventory levels or at times of highest activity. A warehouse at 50 percent stocking level has a very different RF footprint than the same warehouse at 100 percent. Activity levels: In the same manner, an office full of unoccupied cubicles after hours will have a different RF footprint than the same area full of people during the day.
3-4
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Multipath Distortion Multipath distortion is caused by radio reflections. The higher the number of radios in a cell, the higher the noise level in the cell; therefore, the access point antennas need placements that are apart from reflective surfaces.
NEVER MOUNT ANTENNAS NEAR METAL OBJECTS OR OUT OF PHASE
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-6
Because of multipath reception, the signal strength may be strong, but it may also be distorted. Closer does not guarantee better performance. The closer the antennas are, the stronger ALL paths are, including reflected paths and the stronger the possibility of interference from reflected paths. The farther the distance is, the greater the difference between reflected and direct (primary) signal. The farther distance makes for decreased signal strength but also reduces the strength of any reflected signal. Here are some guidelines pertaining to areas vulnerable to multipath distortion: A low RF signal strength does NOT mean poor communication. A low signal quality DOES mean poor communication. Multipath distortion is a high concern in manufacturing and should also be given considerable attention in warehousing and patient areas in hospitals. Omnidirectional antennas must be mounted vertically with the base at the top. Patch and Yagi antennas should not be turned 45 degrees. A signal that is not a polarized match between the sending and receiving antennas is seen as noise and is rejected.
Copyright © 2004, Cisco Systems, Inc.
Manual Site Survey Utilities and Techniques
3-5
Diversity Antennas Use antennas with integrated diversity radiating elements when possible.
When that is not possible, use matching cables and cable lengths, and matching antennas.
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-7
Diversity antennas are designed to cover the same radio cell. Directional antennas may also be used if they are aimed in a similar manner so that coverage cells are the same. The access point uses only one antenna at a time, and it does NOT sample the other antenna port unless it is having difficulty. Therefore, if the directional Yagi antenna was used and the access point was in communication with a client far away, it might not hear a nearby client on the omnidirectional antenna or vice versa. The higher the utilization requirements and the higher the density of users, the more important it is to have a well-designed diversity solution. As the number of wireless users increases, more signals are present, creating more possibilities for nulls (dead spots) and multipath distortion (radio reflections).
3-6
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Typical WLAN Topologies Wireless Cell
Channel 1
Wireless Cell
Channel 6
Access Point
Wireless Clients
© 2004 Cisco Systems, Inc. All rights reserved.
Overlapping 10-15%
LAN Backbone
Access Point
Wireless Clients
CAWSS 4.04-8
The basic service area (BSA) is the area of RF coverage provided by an access point, also referred to as a microcell. To extend the BSA, or to simply add wireless devices and extend the range of an existing wired system, an access point can be added. (As the name access point indicates, this unit is the point at which wireless clients can access the network.) The access point attaches to the Ethernet backbone and communicates with all the wireless devices in the cell area. The access point is the master for the cell, and controls traffic flow to and from the network. The remote devices do not communicate directly with each other; they communicate with the access point. If a single cell does not provide enough coverage, any number of cells can be added to extend the range. This grouping of cells is known as an extended service area (ESA). It is recommended that the ESA cells have a 10 to 15 percent overlap to allow remote users to roam without losing RF connections. Bordering cells should be set to different nonoverlapping channels for best performance.
Copyright © 2004, Cisco Systems, Inc.
Manual Site Survey Utilities and Techniques
3-7
Evaluate Possible Problem Areas Elevator Office Shafts
File Room or Supply Room: Large Filing or Metal Cabinets
Test Lab
Break Room: Microwave Ovens
Conference
Cubicles
© 2004 Cisco Systems, Inc. All rights reserved.
Stairwells (Reinforced Building Area) CAWSS 4.04-9
Each different surface in an indoor site will have a different effect on signal reflections or signal absorption. Each device that is running with a 2.4-GHz or 5-GHz frequency will affect the signal-to-noise ratio. Elevator shafts block signals, supply rooms absorb signals, interior offices absorb signals, break rooms may produce 2.4-GHz interference, test labs may produce 2.4-GHz or 5-GHz interference and create multipath distortion and shadows, cubicles absorb and block signals, and conference rooms have high utilization requirements. Expect that 5-GHz equipment will not able to penetrate through walls as well as 2.4-GHz equipment. Tools like CiscoWorks 1105 Wireless LAN Solution Engine (WLSE) can be extremely helpful for setting up access points in a new office, or for changing the configuration of access points in an office where a wireless LAN (WLAN) already exists but needs to be upgraded. If there are a variety of client types and applications, it is a good idea to conduct a walkabout survey with each client. The walkabout with various clients ensures that all clients will receive adequate coverage. The number of access points that are required to provide coverage will vary based on the radio band used, the transmit (Tx) and receive (Rx) characteristics of the clients, the Tx and Rx configurations of the access points, and the types of cable and antennas used with the access points.
3-8
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
From the Outside Looking In
A
Place access point at A Measure maximum range (inside building)
B
Move access point to center of that arc (point B) Test to ensure coverage to corner of building
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-10
Step 1
To determine the coverage characteristics of an enterprise office site, measure from the corner to determine the attenuation, or the radius coverage range for a data rate.
Step 2
Move the access point from the corner to the edge of coverage for the required data rate.
Step 3
Determine the radius coverage range behind stairwells, offices, supply rooms, cubicles, and so on.
Copyright © 2004, Cisco Systems, Inc.
Manual Site Survey Utilities and Techniques
3-9
From the Outside Looking In (Cont.) Continue repeating this process until all the required coverage areas are set up.
CH 1 © 2004 Cisco Systems, Inc. All rights reserved.
Step 4
3-10
CH 6
CH 11 CAWSS 4.04-11
With as many access points as available, build the WLAN coverage. Establish nonoverlapping channels as often as possible to reduce contention.
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Enterprise Office Area 802.11b and 802.11g cell sized reduced by reducing Tx power and using dipole antennas 802.11b and 802.11g used for normal network connection 140 users per floor 6 access points = 66-Mbps aggregate data rate per floor for 11b and 324 Mbps for 11g
CH 1
© 2004 Cisco Systems, Inc. All rights reserved.
CH 6
CH 11
CAWSS 4.04-12
Step 5
Use the survey tools to create data points that will report the performance in all locations of the floor.
Step 6
Walk around the covered areas with as many client device samples as possible to verify performance.
Step 7
Adjust the Tx power of the access points or adjust the antenna placements to best fit the results of the walkabout performance data.
Step 8
Verify that the conference room has enough bandwidth to satisfy the number of users that may be in the room.
Step 9
Verify that the potential sources of interference do not overly disrupt throughput.
Copyright © 2004, Cisco Systems, Inc.
Manual Site Survey Utilities and Techniques
3-11
Increase Office Bandwidth Performance with Dual Band Access Points 5 Ghz has nonoverlapping channels May decide to reduce cell size a bit more 6 11a access points @ 54= 324 Mbps 6 11g access points @ 54= 324 Mbps Total bandwidth= 348 Mbps
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-13
The 2.4-GHz signal has a wavelength of 12.5 cm, and the 5-GHz signal has a 6-cm wavelength. The 5-GHz signal will not penetrate through walls as efficiently as the 2.4-GHz signal, so if the site is to be covered with an equal number of 2.4-GHz and 5-GHz access points, then the Tx power of 2.4-GHz access point radios may need to be turned down. To survey the site for 5 GHz, repeat the steps used for 2.4 GHz.
3-12
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Multifloor Survey
AP 4
AP 3
AP 2
AP 1
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-14
Enterprise offices, hotels, hospitals, and schools are likely to be multifloor facilities. Special caution needs to be taken when you are surveying multifloor facilities. Access points on different floors may be able to interfere with each other as easily as access points located on the same floor. It is possible for engineers to use this situation to their advantage during a survey. Using larger antennas, engineers may find it possible to penetrate floors and ceilings and provide coverage to floors above as well as below the floor where the access point is mounted. In the example shown in the slide, a four-story office complex needed to be covered. A single access point would not cover an entire floor. Mounting two access points on each floor would have been expensive and might have presented a problem with access points on the same channel overlapping. Using patch antennas on the access points solved the problem. Because the patch antenna was more powerful and semidirectional, there was enough coverage from each access point to cover most of one floor and a portion of the floors above and below it. By mounting access points on alternating floors and at opposite ends of the building, the site engineer was able to achieve the desired coverage with only four access points. In a multitenant building, there may be security concerns. The customer may desire lower Tx powers and lower gain antennas so that the signal is kept out of neighboring offices.
Copyright © 2004, Cisco Systems, Inc.
Manual Site Survey Utilities and Techniques
3-13
Healthcare Facility Survey All antennas are diversity omnidirectional ceiling-mounted antennas except courtyard antenna
Survey was based on 11 Mb Antennas are diversity omnidirectional ceilingmounted (blends in well) except courtyard Works well except radiology
6-dBi Patch Antenna
© 2004 Cisco Systems, Inc. All rights reserved.
Radiology
Courtyard
Antenna Locations Channel 1 Channel 6 Channel 11
CAWSS 4.04-15
The surveying process for a hospital is much the same as for an enterprise. The condition that may be different is the layout of the facility. Signal penetration through the wall and floors in the patient areas is minimal. The need for bandwidth is increasing as WLAN ultrasound equipment and other portable imaging applications gain acceptance. Hospitals are also beginning to use WLAN IP phones. Healthcare cells are small, and seamless roaming is important. Cell overlap can be high, and channel reuse can be high. Hospitals may have several types of wireless networks installed. There could be contention with other 2.4-GHz or 5-GHz networks. Diversity wall-mounted patches and diversity omnidirectional ceiling-tile-mounted antennas are popular.
3-14
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
School Building 1200 Series Access Point with patches for the auditorium 1200 Series Access Point with Yagi for the courtyard 1200 Series Access Point with omnidirectional ceiling-mounted antennas for the hallways
Auditorium
Courtyard
Channel 1 Channel 6 Channel 11 Channel 48 © 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-16
Access point locations must also include the locations of Ethernet drops. The illustration shows that the access point location in the auditorium on the far end may not work. It is not likely that Ethernet is run to the far end of the auditorium. Most likely the Ethernet drop will be on the inside wall.
Copyright © 2004, Cisco Systems, Inc.
Manual Site Survey Utilities and Techniques
3-15
Freezers and High Warehouse Racking
o
Freezer 0 F
o
Freezer -5 F
© 2004 Cisco Systems, Inc. All rights reserved.
o
Freezer -20 F
CAWSS 4.04-17
A distribution center is shown in this figure. The center stores perishable items. Different areas of the center are kept at different temperatures. Some of the areas are freezers with temperatures as low as 20°. Installing access points in areas with temperatures this low may require expensive heated enclosures to protect the access points. The access point can be mounted outside the freezer with the antenna providing an area of coverage inside the freezer. Beyond the savings from not having to buy the expensive heated enclosure, the customer also saves the cost of the extensive time that it would take to install cable and power inside the freezer. Installing this type of equipment while wearing a subzero suit and heavy gloves can take quite a bit of time and be very expensive. Warehouses have wide, open areas and high, tight racks. The stocking will determine the number of access points. The engineer should test coverage with two or three access points in estimated placement locations. Unintentional WLAN cell overlap may occur due to high multipath distortion, and may be unavoidable. This situation may be observed when signal quality varies noticeably more than the signal strength, or when clients appear to have better throughput to access points located farther away. Survey using the antennas and cable that you intend to use. A common mistake is to survey without consideration for antenna cables that are added later during the installation, causing further degradation, given that all antenna cables contribute to signal loss. The most accurate survey will include the type of antenna to be installed and the length of cable to be installed. A good tool to use to simulate the cable and its loss is the attenuator in the survey kit. Once the coverage areas are fairly well understood, the engineer should test for the various client types. If the true client cannot be tested, the engineer should set test hardware and software to the Tx power and data rates that most closely emulate the true clients. The clients should have the necessary throughput requirements within the cell but also should roam efficiently. The installed access points should be set to channels 1, 6, and 11. Dynamic channel selection in warehouse applications really does have a benefit. Some client radios that see a lot of different channels may not roam efficiently. 3-16
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
The mapping tools in AirMagnet and Cisco Works WLSE will provide effective surveys if enough data points are taken.
Manufacturing Aircraft manufacturing floor(802.11b and 802.11g) Normal network connectivitymedium bandwidth bar coding limited bandwidth printing invoices (802.11b and 802.11g) Video images for inspection, troubleshooting high bandwidth (802.11a) IP phonelimited use, medium bandwidth (802.11b and 802.11g) 6 Access Points Provide 802.11b and 802.11g Coverage 6 Dual-Band Access Points Provide 802.11b and 802.11g, 802.11a Coverage © 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-18
Surveying for manufacturing is the same as it is for warehousing, although there may be more sources of interference. The applications for a site, such as video imaging, may be bandwidthintensive. In such an instance, multipathing is likely to be the greatest performance problem.
Copyright © 2004, Cisco Systems, Inc.
Manual Site Survey Utilities and Techniques
3-17
Sources of RF Degradation
Multipath distortion Colocation of access points 802.11b clients in an 802.11g cell Channel reuse Cable length and connections Hot standby Surrounding facilities Position of antennas in a laptop Position of crystals on a laptop motherboard
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-19
When colocating 802.11b access points in the same cell, the engineer should space the access points a minimum of five feet apart. Having access points too close together can cause signal degradation from cross-channel RF interference or receiver capture effect. When you are colocating 802.11g access points in the same cell, due to the nature of Orthogonal Frequency Division Multiplexing (OFDM) and frequencies being closer together than with 802.11a, it is recommended that a distance greater than five feet be observed when possible. The 802.11a specification was designed with OFDM modulation in mind. 802.11a does not have overlapping channels. 802.11b uses Complementary Code Keying (CCK) modulation at 5.5 and 11 Mbps, which does not have the side-band issues that OFDM has. When OFDM was adopted for 802.11g transmit, power had to be lowered so that the side-band issues with OFDM would not be a problem within the 2.4-GHz 802.11 and 802.11b channels. When 802.11b clients and 802.11g clients are in the same cell, the 802.11g specification requires a protection mechanism that involves the use of the 802.11 Ready to Send (RTS) and Clear to Send (CTS) protocols. It is the protection mechanism of 802.11g that slows the throughput of 802.11g clients, when there are 802.11b clients in the coverage cell. The protection mechanism is not active when the cell has only 802.11g clients. With the protection mechanism active, the access point still transmits to the clients at rates up to their capabilities. The protection mechanism slows 802.11g throughput but provides for the fewest collisions of packets. Laptops may have antennas located in the lid or in the main shell. If the engineer is surveying with a laptop, he or she should use a laptop with the antenna in the lid. Also, most laptops have crystals that generate 2.4-GHz signals. Some laptops can have bad performance on different channels, because of the signals generated. Check the performance of all channels before surveying. Channel reuse is acceptable if the channels of 1, 6, and 11 are already used in a cell. The engineer may use 1, 6, or 11, but not an overlapping channel like 2, 3, 4, 7, 8, 9, or 10.
3-18
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Cable length and connections degrade signal strength and can cause signal loss. A hundred feet of antenna cable may have a 6-dB loss. A connector may have a 0.5-dB loss. Hot standby does not cause RF contention or degradation. The radio of the hot standby does not transmit while the standby access point is monitoring the primary access point. Surrounding facilities may have channels with signals that carry over into other facilities. Those channels should be avoided if possible.
Copyright © 2004, Cisco Systems, Inc.
Manual Site Survey Utilities and Techniques
3-19
Software Tools There are many software tools available to help the site survey engineer conduct the site survey. This topic discusses some of those tools.
Client Software Tools for Surveys
Cisco ACU AirMagnet site survey tool Cisco Wireless IP Phone 7920 The CiscoWorks WLSE survey services Settings for the Cisco Aironet AP running Cisco IOS Software Using Operating System pings
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-20
The software tool(s) selected for the survey will depend on the level of completeness of the site infrastructure. Using Cisco Works WLSE requires an existing wired LAN and the installation of the Cisco Works WLSE appliance. The other tools can be used with little or no infrastructure. The access point will need to be configured for the data rates required for each software tool selected for use. Placement of access points should begin with best guesses and Tx power settings. These can then be adjusted based on the results of walkabout testing with various clients. Not all clients have the same antenna gain, antenna Rx performance, Tx power, or receiver sensitivity. The client radio used with the survey tools should be adjusted to emulate the client radio performance as closely as possible. A search of the vendor website may produce a data sheet with the specifics of the performance of the radio. All devices with a radio will have a Federal Communications Commission (FCC) ID. The FCC website has PDF files of the radio. Use the first three characters of the FCC ID to search for the radio data. The site is at https://gullfoss2.fcc.gov/prod/oet/cf/eas/reports/GenericSearch.cfm. The Cisco Aironet Access Point has an ID of LDK.
3-20
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
ACU Site Survey Tool
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-21
To use the Aironet Client Utility (ACU) site survey tool, following these steps: Step 1
In order to see the actual figures instead of percentages, choose Preferences from the main screen.
Step 2
In the box titled Signal Strength Display Units, check dBm (decibels per milliwatt).
From this screen the engineer can also choose to have seconds displayed on the clock in the status bar on the main screen as well as specify how often the screen is updated. By default, the screen update parameter is set to 1 second (the lowest available setting) to ensure that the information read is as accurate as possible. When returning to the Site Survey screen, the engineer will see that the figures are now being displayed as dBm measurements instead of percentages. This information allows the surveyor to be more accurate in reading and interpreting the results.
Copyright © 2004, Cisco Systems, Inc.
Manual Site Survey Utilities and Techniques
3-21
ACU Site Survey Tool (Cont.)
© 2004 Cisco Systems, Inc. All rights reserved.
Note
CAWSS 4.04-22
The ACU is in passive mode in the example that is shown here. The ACU has two modes while you are running a site survey: passive and active.
In passive mode, the ACU does not initiate any RF network traffic; it only listens to any other RF network traffic that the Cisco WLAN adapter hears (from the associated access point). To set up active mode, click the Setup button at the bottom of the screen. Step 3
If the Setup button is grayed out, it indicates that the client is using a version of firmware that does not support active mode. Upgrade the firmware. Active mode is more representative of an actual application because it has directed packets to and from the access point. The destination MAC address should be that of the access point that you want to test coverage to. This specification keeps the client from roaming to another access point.
Step 4
As a general rule, uncheck the field for Destination Is Another Cisco Device. The packet size should be set to a size that is representative of the size that is used for the applications that are used at the site. Pick the largest packet size that is used. The larger the packet, the more likely that the packet will become corrupted. The data rate should be set to the highest data rate that is desired by the customer. The higher the data rate, the smaller the size of cell for the modulation type.
3-22
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
ACU Site Survey Tool (Cont.)
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-23
Step 5
Once you are satisfied with the settings, click the OK button to return to the Site Survey screen.
Step 6
Now click the Start button to start the site survey in active mode. The Site Survey: Percent Complete: Shows the percentage of packets that have been sent. If a continuous link test has been selected, it shows the percentage of packets that have been sent until it reaches 100 percent; then it starts over again. Percent Successful: Shows the number of packets that have been successfully sent and received. Notice the red threshold line. If the percentage drops below this line, the bars will become yellow. Lost to Target: Shows the number of packets that were lost between the client and the access point. Lost to Source: Shows the number of packets that successfully reached the access point but did not reach the client.
Step 7
To stop the survey, click Stop or OK.
Copyright © 2004, Cisco Systems, Inc.
Manual Site Survey Utilities and Techniques
3-23
ACU Site Survey Tool (Cont.)
Signal-to-noise ratio: 10+ dB at 11 Mbps 8+ dB at 5.5 Mbps 6+ dB at 2 Mbps 4+ dB at 1 Mbps
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-24
When you are performing the site survey, the signal-to-noise ratio needs to stay above a given figure, based upon the data rate. The signal and the noise levels may fluctuate, but if the signalto-noise ratio remains at or above the given level, then the signal can be considered reliable. Listed here are the figures for receiver sensitivity (signal strength) and maximum noise levels for the Cisco Aironet 350 Series: -85 dBm at 11 Mbps (maximum noise level -75 dBm) -89 dBm at 5.5 Mbps (maximum noise level -81dBm) -91 dBm at 2 Mbps (maximum noise level -85 dBm) -94 dBm at 1 Mbps (maximum noise level -90 dBm) Note
3-24
Figures on signal strength are conservative. It may be possible to go below a figure and still remain connected. For example, at 11 Mbps the minimum signal strength is -85 dBm. It is likely that a client would remain connected at a value as low as -90 dBm.
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
AirMagnet Survey AirMagnet uses the Aironet CB21AG.
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-25
The AirMagnet laptop program uses the Cisco Aironet A, B, or G CardBus wireless client. The AirMagnet Windows CE program uses the Cisco Aironet PCM350 card. Note
The AirMagnet laptop program uses the Cisco Aironet 802.11a/b/g CardBus Wireless LAN Client Adpater. The AirMagnet Windows CE program uses the Cisco Aironet 350 Series Wireless LAN Client Adapter.
AirMagnet is a third-party utility.
Copyright © 2004, Cisco Systems, Inc.
Manual Site Survey Utilities and Techniques
3-25
Site Survey Passive Mode Data Collection Walkabout Complete Path
Each red dot located on the floor represents a data point taken by the AirMagnet client utility during the walkabout.
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-26
Where Do You Start? Characterize clients: Find a spot near the fringe for the primary client device. Test each flavor of client radio and antenna system. Basic Placement Strategy Initial placements: Acquire a horizontal and vertical test plot in each location: Set up in center of zone. Set up at edge of zone. Antennas: Try factory dipole (diversity if possible) or higher-gain omnidirectional ceiling mounted antenna, or wall-mounted patch. Establish the best guess for access point and antenna placements to begin surveying. Coverage zone requirements:
Link speed: Auto rate shifting means that clients will downshift as soon as the link margin is hit. For 802.11b, excellent results can be gained if the lock tests the access point at 5.5 Mbps to find hard fringe.
Overlap to adjacent zone: Standard cells: Target 20 percent area Microcells: Target 5 percent area
Channel usage: Use as many as allowed by interference field.
3-26
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Display Mode Merged Link Speed The merged data point information is projected onto the floor plan.
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-27
From the data point information that was collected during the walkabout, AirMagnet is able to develop several views. This view shows the display of link speed. Data is merged together from all data elements selected by the filters. The speed display shows the maximum link rate that is supported during the data traffic flow between the Surveyor station and the test access points during the survey walkabout.
Copyright © 2004, Cisco Systems, Inc.
Manual Site Survey Utilities and Techniques
3-27
Cisco Wireless IP Phone 7920 Site Survey The 7920 does have a limited survey tool It uses RSSI value to determine cell size. The tool presents a list of access points. From the menu choose Network Config > Site Survey.
1 (A), SATC..,18,0 4 (A), SATC.., 31,0 10 (C), SATC.., 48, 0
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-28
Three access points are shown here. To use the Cisco Wireless IP Phone 7920 as a site survey tool, following these steps: Step 1
Set the Cisco Wireless IP Phone 7920 with a service set identifier (SSID) that matches the SSID of the survey access point.
Step 2
Set a static IP address that is in the range of the IP address of the survey access point: fields in list equal: channel#, (status), ssid, rssi, cu channel # 10 would be channel 10 status: (C) for status means connected channel; (A) means nonoverlapping channel of associated channel ssid: SATC is the first four characters of the SSID rssi: 48 is the received signal strength in dBi cu: 0 is the channel utilization that the phone receives from the access point if QBone Scavenger Service (QBSS) is enabled; 0 equals not enabled: move cursor to one of the access points in the list and select detail to get more information on the access point SSID: SATCHMO channel:1 (A) RSSI:18 CU:0 MAC: 012345abcdef
The recommended cell edge Received Signal Strength Indicator (RSSI) value for a Cisco Wireless IP Phone 7920 phone with an 802.11b radio is 20. To simulate the Cisco Wireless IP Phone 7920 with ACU, the engineer must set the packet size to 256 and set the successful percent threshold to 99. Because the default transmitter power of the Cisco Wireless IP Phone
3-28
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
7920 is 20 mW, the engineer should set the Tx power of the 350 radio down to 20 mW as well. The goal is to maintain a signal-to-noise ratio of better than 20 dBm.
Copyright © 2004, Cisco Systems, Inc.
Manual Site Survey Utilities and Techniques
3-29
Access Point Survey Configuration
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-29
Follow these steps to configure the Access Point for the survey: Step 1
Set the access point to Fallback to Radio Island. This setting lets clients associate whether or not the access point has an Ethernet connection. This ability is useful when you are configuring access point security features or for surveying without actually connecting the access points to the live network.
Step 2
Set the data rates as required by the customer.
An 802.11g access point must have a required data rate of 1, 2, 5.5, or 11 before an 802.11b client will associate. If there is an 802.11g data rate set as required, then 802.11b clients will not associate. If the engineer is surveying for only 2.4 GHz, disable the 5-GHz radio in a dual radio access point. If the engineer is surveying for only 2.4 GHz and the client card is a dual-band card, then a client profile that disables the 5-GHz radio should be used. It is advised, when an engineer does a survey for a site that includes 2.4 GHz and 5 GHz, that two client profiles be set up, one for each band. It is also advised that different SSIDs be used for the different bands.
3-30
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Access Point Survey Configuration (Cont.)
© 2004 Cisco Systems, Inc. All rights reserved.
Step 3
CAWSS 4.04-30
Select the channel as required for the cell.
Access Point Survey Configuration (Cont.)
© 2004 Cisco Systems, Inc. All rights reserved.
Step 4
CAWSS 4.04-31
Set the antenna diversity to match the antenna type. The default of Diversity should be used for diversity omnidirectional and patch antennas. Right is the correct selection for antennas that are connected to the primary port on the Cisco Aironet 1200 Series Access Point.
Copyright © 2004, Cisco Systems, Inc.
Manual Site Survey Utilities and Techniques
3-31
Access Point Survey Configuration (Cont.)
© 2004 Cisco Systems, Inc. All rights reserved.
3-32
CAWSS 4.04-32
Step 5
Set a static IP address that is unique for each survey access point. That address must be in the range of addresses that are used by the survey clients.
Step 6
Set an SSID that matches the SSID of the survey clients.
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Using OS Pings When it is not possible to load a survey utility on a client, the best option is to send ping packets.
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-33
Use the following steps to send ping packets when a survey utility is not available on the client. Step 1
From the command interface of the client, verify the IP address of the client. It should be static and in the IP address range of the access point. The client must be associated to the access point to run pings over the RF to the access point.
Step 2
Use ping options that allow multiple transmits of the ping packet; set the size of the packet to a value that is representative of the customer applications.
An example of a ping command is -> ping t l 256 10.0.0.154. The t means run until Ctrl-C. The l sets the length of packet to send. The size of the packet that is selected to send to the access point from the client is echoed back to the client by the access point. Engineers must watch the packet times in milliseconds while remaining near the access point, and compare those times with the times measured while moving about the cell. These readings will give you a good idea of the coverage pattern within a cell. When the ping command ends, the success rate of completed packets and other statistics, such as Tx and Rx packets and approximate round-trip times, are displayed in milliseconds. If the client supports Telnet, then from the client side, pings could be sent from the access point using the Cisco IOS command-line interface (CLI) command ping: ×ÑÍ ©·´´ -¸±© -¬¿¬·-¬·½- óâ Ý´·»²¬-æ éóððìðòçê¿ðòíéëé °¿µ ·² ïðçê ¾§¬»- ·² îïïéìé °¿µ ±«¬ ìì𠾧¬»- ±«¬ ïçðíìï ¼«° ïï ¼»½®°§¬ »®® ð ³·½ ³·-³¿¬½¸ ð ³·½ ³·-- 𠬨 ®»¬®·»- íê ¼¿¬¿ ®»¬®·»- íï ®¬- ®»¬®·»- ë -·¹²¿´ -¬®»²¹¬¸ íé -·¹²¿´ ¯«¿´·¬§ Òñß ìóððð½òèëêìòîèí» °¿µ ·² éîçç ¾§¬»- ·² ìëèéîí °¿µ ±«¬ ïðé ¾§¬»- ±«¬ ïêðéë ¼«° ì ¼»½®°§¬ »®® ð ³·½ ³·-³¿¬½¸ ð ³·½ ³·-- ð Copyright © 2004, Cisco Systems, Inc.
Manual Site Survey Utilities and Techniques
3-33
¬¨ ®»¬®·»- ïê ¼¿¬¿ ®»¬®·»- ïê ®¬- ®»¬®·»- ð -·¹²¿´ -¬®»²¹¬¸ íí -·¹²¿´ ¯«¿´·¬§ Òñß Ì¸» ½±³³¿²¼ ¬± -¸±© -¬¿¬Ž- ·- óâ -¸± ¼±¬ïï -¬¿¬ ½´·»²¬ ̸» ½±³³¿²¼ ¬± ½´»¿® -¬¿¬Ž- ·- óâ ½´»¿® ¼±¬ïï -¬ ¼±¬ïïð ÌÓÛó×ÑÍóïëìý¼±¬ïï ¼±¬ïïð ´·²µ¬»-¬ á ½±«²¬ п½µ»¬ ½±«²¬ °»® ¬»-¬ ·²¬»®ª¿´ ײ¬»®ª¿´ ¾»¬©»»² ½±²¬·²«±«- ¬»-¬°¿½µ»¬ó-·¦» п½µ»¬ -·¦» ®¿¬» Í»¬ ¬»-¬ ¾·¬ ®¿¬» ¬¿®¹»¬ ¬¿®¹»¬ ÓßÝ ß¼¼®»-ä½®â ÌÓÛó×ÑÍóïëìý ¼±¬ïï ¼±¬ïïð ´·²µ¬»-¬ ½±«²¬ ïð °¿½µ»¬ó-·¦» îëê ¬¿®¹»¬ ððìðòçê¿ðòíéëé ͬ¿®¬ ´·²µ¬»-¬ ¬± ððìðòçê¿ðòíéëéô ïð îëê ¾§¬» °¿½µ»¬ÌÓÛó×ÑÍóïëìý-¸± ¼±¬ïï ´·²µ¬»-¬ ÙÑÑÜ øî û ®»¬®·»-÷ Ì·³» ͬ®»²¹¬¸ Ï«¿´·¬§ û 묮·»³-»½ û ײ ¼Þ³ û Ñ«¬ ¼Þ³ ײ Ñ«¬ ײ Ñ«¬ Í»²¬ æ ïððô ߪ¹ ë çè ó íì çç ó èï èè ï ̱¬æ ï ì Ô±-¬ ¬± ̹¬æ ðô Ó¿¨ ïï ïðð ó íî ïðð ó êï çç ï Ó¿¨æ ï ï Ô±-¬ ¬± Í®½æ ðô Ó·² ì íê ó éé çç ó èë éê ï כּ- øÍ®½ñ̹¬÷ ïÓ¾ ðñïðð ëìÓ¾ ïððñð
3-34
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Client Statistics on the Access Point
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-34
Browsing the Association page of the access point allows a review of current client statistics. Choosing the clear button will remove the accumulated statistics.
Copyright © 2004, Cisco Systems, Inc.
Manual Site Survey Utilities and Techniques
3-35
Pinging the Client from the Access Point
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-35
Clicking the Ping/Link Test tab will bring up the ping and link test page.
3-36
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Results of the Link Test
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-36
The link test produces a short summary of link performance. The station information and status screen is also updated with the link test information.
Copyright © 2004, Cisco Systems, Inc.
Manual Site Survey Utilities and Techniques
3-37
CiscoWorks WLSE Assisted Site Survey: Process
S ))) ))) )) © 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-37
Cisco Works WLSE builds a module on access-point-to-access-point RF signals. The access points are placed for optimal signal. They usually will have ceiling-mounted or high wallmounted antennas. Clients are generally 3 to 4 feet off the floor and are generally subject to a good deal more attenuation than the access point antennas. For this reason, the Cisco Works WLSE option will factor in the results of a walkabout survey by clients. Cisco Works WLSE uses the data point information from the clients to adjust to the signal levels that are reported by the clients at each data point. Cisco Works WLSE then increases or decreases the Tx power of the access point to provide an adequate signal-to-noise ratio. The signal-to-noise ratio changes depending on modulation type and data rate.
3-38
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
CiscoWorks WLSE Assisted Site Survey: Results
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-38
After all the survey steps are completed, Cisco Works WLSE produces a floor layout of the site like that in the figure here. Cisco Works WLSE can also produce a mapping that shows the dBm values throughout the floor.
Copyright © 2004, Cisco Systems, Inc.
Manual Site Survey Utilities and Techniques
3-39
Cell Coverage LimitationsParameters to Watch Minimum signal-to-noise ratio Provides a level of good signal over noise floor Minimum signal strength Watch for: Consistent values Minimum values Rapid fluctuations (indicates multipath distortion) Noise Floor Higher noise floor will affect minimum signal strength Packet counts, lost packets Use packet sizes similar to those for the applications that have the largest packet size. © 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-39
When performing the survey, the engineer must set parameters and thresholds to identify where the cell edge should be placed. To do this correctly requires that the engineer watch several key items. Many surveyors use only signal strength, but that is not enough alone. Surveyors should also watch the noise floor, and the ratio between the signal and noise. Also, when possible, they should watch packet transfer performance (packet count) or ping times for packets moving between access points and clients.
3-40
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Using Pings for Surveys Ping packets can be used to survey when: the client does not have survey tools the assisted site survey is not supported (no WLSE)
Set ping packet size to represent the largest packet size of the known WLAN applications to be used
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-40
The site survey engineer can use ping packets to survey when the client does not have survey tools or does not have assisted survey awareness. To do so, the engineer sets the device to an IP address in the range of the access point. Next, set the access point to the required data and determine the packet size to be tested. Most ping commands have the following syntax: ping -t (continues pings) or -n xx (number of packets to send where xx is a number) -l xx (length-size of packet to send), then the IP address of the device to be pinged The command -> ping -t -l 1024 10.0.0.1 will do a continuous ping to the device with the address of 10.0.0.1. Each successful ping will print a time value in milliseconds. The time value is how long that it takes for 1024 bytes to reach the remote device and for the device to reply with a same size packet. To end the test for that data point, the engineer presses Ctrl-C. A short report will be displayed showing the number of packets tested, how many were received, and the best, worst, and average times. In a busy 802.11g WLAN network with 29 percent utilization, pinging through the cubicle farm of an office generated the following results: Distance
15 ft
40 ft
80 ft
Fixed data rate 6 Mbps
19 ms 23 ms 41 ms
24 Mbps
5 ms
7 ms
48 Mbps
5 ms
13 ms 34 ms
12 ms
The increase in average time at 80 feet for 48 Mbps is a result of a 23 percent missed-packet count.
Copyright © 2004, Cisco Systems, Inc.
Manual Site Survey Utilities and Techniques
3-41
Recommended Parameters for 2.4-GHz Data Networks Data Rate
RX Threshold (RT)
Recommended Minimum RT
RX Signal-toNoise Ratio
Recommended Minimum Signal-to-Noise Ratio
54
-71
-61
25
35
36
-73
-63
18
28
24
-77
-67
12
22
12/11
-82
-72
10
20
6/5.5
-89
-79
8
18
2
-91
-91
6
16
1
-94
-84
4
14
Minimum packet performance should be greater than 90 percent successful packet transfer (10 percent lost). When viewing ping times, watch for consistent times, as well as missed pings. © 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-41
This table indicates specifications for the Cisco Aironet 802.11g radio parameters. The Cisco Aironet 802.11b radio specifications at data rates of 1, 2, 5.5, and 11 are nearly identical to the 802.11g radio, so either radio may be used when surveying at 802.11b data rates. The values vary for different data rates, and the data rate at which the engineer is surveying needs to be noted for minimum performance. The minimum Rx threshold (RT) indicates the absolute minimum that the receiver can hear and still properly decode the packet. This value needs to have some padding in order to compensate for variations in transmitters, receivers, and environment. A typical padding of 10 dB is sufficient. The recommended minimum RT indicates the value that the engineer should watch for to indicate the edge of reliable coverage. The signal-to-noise rating indicates the minimum the ratio between the noise floor and the desired signal level for proper reception of information. The recommended signal-to-noise value provides a 10-dB padding to compensate for variations as previously identified. Both values should be monitored for minimum values. As the noise floor changes, this change can affect the minimum signal strength that is needed. At the same time, the packet performance should be monitored to provide a minimum of 90 percent successful packet transfer.
3-42
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Recommended Parameters for 2.4-GHz Networks with Cisco Wireless IP Phone 7920 VoIP Traffic Voice systems require a more stringent survey, and stronger signal levels to ensure good voice quality and minimum jitter. Data Rate
RX Threshold (RT)
Recommended Minimum RT
RX Signal-toNoise Ratio
Recommended Minimum Signal-to-Noise Ratio
54
-71
-56
25
40
36
-73
-58
18
33
24
-77
-62
12
27
12/11
-82
-67
10
25
6/5.5
-89
-74
8
23
2
-91
-76
6
21
1
-94
-79
4
19
Minimum packet performance should be greater than 90 percent successful packet transfer (1 percent). © 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-42
When you are surveying for systems that will include voice systems, the signal strength and signal-to-noise ratio need to be a bit higher to prevent voice quality degradation and jitter. It is recommended that the padding values be increased to 15 dB, and the packet lost count gets reduced to 1 percent if possible. It may also be advisable to perform the survey using the values listed here for the minimum data rate to be used in the WLAN, and then compare this information to a sampling of survey measurements using the phones survey utility.
Copyright © 2004, Cisco Systems, Inc.
Manual Site Survey Utilities and Techniques
3-43
Recommended Parameters for 5-GHz Data Networks Data Rate
RX Threshold (RT)
Recommended Minimum RT
RX Signal-toNoise Ratio
Recommended Minimum Signal-to-Noise Ratio
54
-68
-58
20
30
36
-73
-63
14
24
24
-77
-67
12
22
12
-82
-72
7
17
6
-85
-75
5
15
Minimum packet performance should be greater than 90 percent successful packet transfer (10 percent lost). When viewing ping times, watch for consistent times, as well as missed pings. © 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-43
The method of measuring the cell edges at 5 GHz is very similar to the 2.4-GHz recommendations. The values will vary a bit, and the overall receivers are different. Similar to 2.4-GHz data networks, a 10-dB padding is also included here.
3-44
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Summary This topic summarizes the key points discussed in this module.
Summary Site survey situations and obstacles Site survey software tools Limitation of cell boundaries
© 2004 Cisco Systems, Inc. All rights reserved.
Copyright © 2004, Cisco Systems, Inc.
CAWSS 4.04-44
Manual Site Survey Utilities and Techniques
3-45
Review Questions Use the practice items here to review what you have learned in this module.
Review Questions How can the number of users determine the necessary data rate? Will 11 or 54 Mbps necessarily be needed if only data collection equipment is being used? What standard defines characteristics of wireless LANs?
© 2004 Cisco Systems, Inc. All rights reserved.
3-46
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
CAWSS 4.04-45
Copyright © 2004, Cisco Systems, Inc.
Module 4
Using the AirMagnet Site Survey Tool for a Manual Survey Overview This module explores the steps that are involved in a manual site survey using the AirMagnet site survey tool, and ways to correct many of the common problems that arise.
Module Objectives Upon completing this module, you will be able to complete the objectives shown in the figure.
Module Objectives Describe a DSA coverage audit Describe the AirMagnet site survey tool and its use Identify common situations and obstacles that are encountered in a manual site survey and how to correct those problems
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-2
Module Outline The outline lists the components of this module.
Module Outline Overview DSA Coverage AirMagnet site survey tool Manual Survey Situations and Obstacles Summary Review Questions
© 2004 Cisco Systems, Inc. All rights reserved.
4-2
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
CAWSS 4.04-3
Copyright © 2004, Cisco Systems, Inc.
DSA Coverage Determining what the designated service area (DSA) will be is the beginning of wireless LAN (WLAN) development. This topic covers DSA coverage.
Establish DSA Designated service area = Where authorized user will get full-featured connection service with a specified 802.11a/b/g radio at specified data rate
DSA Boundary
Example: Access Point Coverage (802.11b @ 11 Mbps service) © 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-4
A DSA is an area where the survey will be performed and WLAN coverage is desired.
Copyright © 2004, Cisco Systems, Inc.
Using the Air Magnet Site Survey Tool for a Manual Survey
4-3
Establish X-DSA Excluded designated service area = Where NO connection service is available or desirable
DSA Boundary
© 2004 Cisco Systems, Inc. All rights reserved.
Service Bulge
CAWSS 4.04-5
An excluded DSA (X-DSA) is an area where no WLAN coverage is desired. In the figure, the X-DSA is the area outside the ovals.
4-4
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Design for Sharp DSA Edge
DSA Boundary
Simple design measures: Use microcells at perimeter: Low Tx power Basic rates 11 and 5.5 Mbps only (for 802.11b) Likely to need more access points Do not cover lobbies or other visitor areas unless it is required by the customer. © 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-6
To get WLAN coverage strictly within or as close as possible to the DSA areas, design the WLAN with smaller cells or with microcells. Techniques like no data-rate-shifting and limiting the power output on the access points can lower available power outputs. An engineer will most likely use more access points to obtain DSAs with sharper edges.
Copyright © 2004, Cisco Systems, Inc.
Using the Air Magnet Site Survey Tool for a Manual Survey
4-5
DSA Coverage Audit
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-7
The survey or IT team may perform a DSA coverage audit using AirMagnet or other wireless analyzers. The audit provides information on the available wireless coverage and the access points providing the coverage.
4-6
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Step 1: Where Do You Start? Where coverage is needed: Within 100 m of existing Ethernet switch port Highest altitude possible, in clearest area (easy to service)
Characterize clients: Find a spot near the fringe for the primary client device Test each type of client radio and antenna system
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-8
The site survey engineer begins where coverage is most needed: within 100 m of an existing Ethernet switch port, at the highest altitude possible, and in the clearest area (easy to service). The engineer should find a spot near the fringe for the primary client device and test each type of client radio and antenna system.
Copyright © 2004, Cisco Systems, Inc.
Using the Air Magnet Site Survey Tool for a Manual Survey
4-7
Step 2: Basic Placement Strategy Initial placements: Acquire horizontal and vertical test plot in each location: Set up in center of zone Set up at edge of zone
Antennas: Try factory dipole (diversity if possible) Try higher-gain, omnidirectional (central, high altitude) or patch (drop ceiling, wall mount) Use real access point and client computer or radio as survey device, if possible in the real user positions.
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-9
The site survey engineer will acquire a horizontal and vertical test plot in each location. The first task is to set up in the center and the edge of the zone. The engineer can first try a factory dipole (diversity if possible), a highergain, omnidirectional antenna (central, high altitude), or a patch antenna (drop ceiling, wall mount). A real access point and client computer or radio is recommended as a survey Device Under Test (DUT), in the real user position.
4-8
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Step 3: Coverage Zone Specs Link speed: Auto rate shifting means that clients will downshift as soon as link margin is achieved For 802.11b, great results achieved if the access point is locked at 5.5 Mbps for the test; find hard fringe during the test
Channel usage: Use as many as allowed by interference field
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-10
The engineer must configure a wireless link speed. Auto rate shifting means that clients will downshift as soon as the link margin is hit. When you are surveying with an 802.11b radio, greater results are achieved if the test access point is locked at 5.5 Mbps to find a hard fringe of the DSA. To achieve good cell overlap to an adjacent cell, follow these rules: In standard cell deployments, target 20 percent area overlap. In microcell deployments, target 5 percent area overlap. The engineer can use as many channels as allowed by the interference field.
Copyright © 2004, Cisco Systems, Inc.
Using the Air Magnet Site Survey Tool for a Manual Survey
4-9
Survey with Two Access Points More accurate:
Must for microcell designs
Best way to verify overlap Identify any multicell fade patterns
With both on, start locked to one access point
© 2004 Cisco Systems, Inc. All rights reserved.
Let it roam, verify overlap, check stickiness
CAWSS 4.04-11
If two or more access points are used at the site, then the engineer should use two or more access points to test coverage and roaming.
4-10
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
AirMagnet Site Survey Tool The AirMagnet Surveyor is a very easy-to-use, yet comprehensive tool for performing WLAN site surveys. Using intuitive graphical interfaces for the collection and display of survey data, designers can very quickly make design decisions on access point placement and configuration. This topic discusses use of SiteViewer.
AirMagnet Site Survey Tool
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-12
The SiteViewer opening screen shows the three main areas of the workspace. On the lower toolbar are the control buttons to toggle between the survey (data collection) mode, and the display (data presentation) mode. The upper left is the data catalog area, where different sets of survey data are listed and can be individually enabled or disabled in display mode. The lower left is the survey tool control area, where depending on the mode, the data collection or data manipulation controls are displayed. The main area on the right is the window for displaying the floor or building plan graphics, with overlays for the access point locations and survey data rendering.
Copyright © 2004, Cisco Systems, Inc.
Using the Air Magnet Site Survey Tool for a Manual Survey
4-11
Start New Project: Import Floor Plan
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-13
The first step for creating a new project is to import the floor or building plan graphics file(s) and specify the scale. Many popular graphics file formats are supported.
4-12
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Set Up Survey Data Collection Mode
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-14
A floor plan has been imported for an office suite. The rulers and all measurements are derived from the scale provided or interpreted from the drawing file.
Copyright © 2004, Cisco Systems, Inc.
Using the Air Magnet Site Survey Tool for a Manual Survey
4-13
Select Specific Access Point to Survey with Active Mode Tool
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-15
There are two modes for collection of survey data: Active mode: With active mode, the SiteViewer NIC (network interface card) associates to an access point and sends round-trip data packets to the access point. Active mode most closely simulates a real WLAN environment, so it is strongly recommended that this mode be used for initial access point surveys. Active mode allows the resulting survey data to be displayed in several different views, including by the link speed that is achieved at each location. Active mode supports two connection methods:
Specific access point: The NIC will associate only to a specific access point that is selected in the access point drop-down menu.
Service set identifier (SSID): The NIC will associate to the best access point that matched the SSID chosen in the drop-down menu. In this mode, the NIC will roam between access points that have the same SSIDin the case where more than one access point is active in the area being surveyed. This mode most closely simulates the actual behavior of a client in the real network. The survey tool status panel always displays the SSID and MAC of the access point that is currently associated to the NIC.
Passive mode: With passive mode, the SiteViewer NIC measures the Received Signal Strength Indicator (RSSI) of the packets coming from the access point and records this signal strength data. This mode is most often used for auditing the coverage of an existing network but can also be used in conjunction with active mode in an initial survey.
4-14
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Choose SSID to Survey Group of Access Points Using Active Mode Tool
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-16
This example shows the choice of SSID for active mode using SSID selection.
Copyright © 2004, Cisco Systems, Inc.
Using the Air Magnet Site Survey Tool for a Manual Survey
4-15
Perform Data Collection Walkabout Using Passive Coverage Mode Tool
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-17
This example shows the survey control panel for the passive survey mode. The access points with the strongest signal (up to 6) are dynamically ranked in the window as the survey data is collected. In the ranking, the access point with the strongest signal will be the first one in the list in the control panel, and the access point with the weakest signal will be the last.
4-16
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Begin Site Survey Active Mode Data Collection: First Location
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-18
The engineer should choose a suitable location for the test access point, create a temporary installation, and turn on the access point. It is recommended that the engineer analyze the ambient radio frequency (RF) environment and then set the test access point on a channel that has no activity in the desired area. To begin the data collection in active mode, the engineer must select a starting position near the perimeter of the area to be covered. The engineer then clicks on this location to indicate the starting point on the floor plan map. A small stick figure will appear in this spot. The engineer can begin the walkabout by moving at a smooth rate to the next vertex in the path; clicking a spot in the floor plan allows you to stop briefly there. As the walkabout proceeds, the survey tool control area displays various real-time data monitoring the instantaneous state of the link. The signal strength, noise level, link speed, and packet loss statistics are all displayed. You can use these indicators to monitor the signal conditions from the test access point and make decisions about the coverage boundary for a given service-level specification. For example, consider an access point cell of coverage that is specified to support a minimum link rate of 5.5 Mbps (for 802.11b). The coverage boundary can be found by walking to points where the speed indicator crosses from 5.5 Mbps to 2.0 Mbps, then moving back into the solid 5.5-Mbps area. In other words, the site survey engineer can find an overlap area, as shown in the previous figure: 20 percent in the standard cell configuration and 5 percent in the microcell configuration. Note
The initial configuration of the active mode survey tool should set the packet size to most closely resemble the data payload of the real WLAN applications. For laptops used mostly for e-mail and Internet browsing, set the packet size to the maximum of 1024 bytes.
Copyright © 2004, Cisco Systems, Inc.
Using the Air Magnet Site Survey Tool for a Manual Survey
4-17
Site Survey Active Mode Data Collection: Walkabout with Stops
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-19
This figure shows a continuation of the active mode walkabout, where the initial path cuts through the central core area where coverage is desired.
4-18
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Site Survey Active Mode Data Collection: Walkabout Complete Path
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-20
This figure shows the complete walkabout path that is taken for this coverage area. Note
The path includes a section outside of the perimeter walls of the building. This kind of path is created to measure the possible propagation outside of the building, where is it usually desired for the signal level to be as low as possible without compromising connectivity to the interior areas. Keeping the signal level as low as possible outside of the building reduces the chance of unauthorized connection to the WLAN.
The signal-level real-time indicator on the active survey tool can be used to monitor the state of the access point signal at a given location, in particular outside the building, which is normally not included in the DSA. The Cisco Aironet 350 Series client NIC will typically lose association to the access point when the signal level drops below -90 decibels per milliwatt (dBm). Most standard WLAN NICs will not be able to establish a connection below this level, so it is usually desirable for the signal level to be below -90 dBm in the excluded designated service area (X-DSA), that is, the outside areas.
Copyright © 2004, Cisco Systems, Inc.
Using the Air Magnet Site Survey Tool for a Manual Survey
4-19
Site Survey Passive Mode Data Collection: Walkabout Complete Path
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-21
This figure shows a similar complete walkabout path for passive mode data collection.
4-20
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Add Access Point Icon to Test Location on Floor Plan Map Graphics
Add AP Button
Add AP Dialogue
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-22
Icons representing the test access point or existing access points in a network can easily be added to the graphics display using a drop-and-drag tool. This view shows the simple procedure: Step 1
Click Add AP on the graphics toolbar on the right side of the screen. The dialogue box will appear to allow addition of a name.
Step 2
Drag the access point icon to the appropriate location on the floor plan map.
Copyright © 2004, Cisco Systems, Inc.
Using the Air Magnet Site Survey Tool for a Manual Survey
4-21
Floor Plan Showing All Access Point Icons and Merged Signal-Level Display
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-23
By clicking the display mode toggle button on the lower toolbar, you can allow SiteViewer to display data collected from the survey. Two new panels appear in this mode: the Filters area in the center left panel, and the map zoom box in the lower left. The procedure is as follows: Step 1
Choose one or more survey data sets to display by clicking the appropriate check box(es) in the data catalog area in the upper left of the screen.
Step 2
Choose the display parameter for the data sets by making a selection from the dropdown menu in the upper right corner of the floor plan display area. The choices include the following: Signal Noise Speed Signal-to-noise ratio
Step 3
Enable appropriate filters to the data (discussed in the next figures).
The survey data will then be displayed as color-coded zones tied to the legend shown. For signal level, shown in this chart, the colors represent 10-dBm levels.
4-22
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Display Mode: Merged Signal Level Using SSID Filter
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-24
There are three types of filters (SSID, channel, and access point) that you can apply to the data sets that are chosen. All filter elements that are chosen are applied together to specify the subset of the data set that will be rendered in the display. Each filter type is presented as a separate tab. When the tab is clicked, all the relevant elements detected in the data set are displayed in a list. Elements with a check box that is checked will be included in the data set display. This view shows the SSID tab data that was captured from at least one access point on each of the SSIDs listed. Only the SSIDs that are used for access points that are designated for use in the coverage survey have their check boxes checked.
Copyright © 2004, Cisco Systems, Inc.
Using the Air Magnet Site Survey Tool for a Manual Survey
4-23
Display Mode: Merged Signal Level Using Access Point Channel Filter
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-25
This view shows the channel filter tab. Only data that is collected on the selected channels will be rendered in the data display area.
4-24
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Display Mode: Merged Link Speed
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-26
This view shows the display of link speed. Data is merged together from all data elements that are selected by the filters. The speed display shows the maximum link rate that is supported during the data traffic flow between the SiteViewer station and the test access point(s) during the survey walkabout. The view also shows the speed data for an active survey in 802.11a mode. The display shows the maximum data rate supported at each location. For this scenario, the green line shows the boundary for the cell that was created by the access point in the lower left corner of the office, where the minimum service level is specified at 24 Mbps.
Copyright © 2004, Cisco Systems, Inc.
Using the Air Magnet Site Survey Tool for a Manual Survey
4-25
Display Mode: Merged Signal-to-Noise Ratio
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-27
This view shows the signal-to-noise ratio data display. The signal-to-noise value is computed from the signal- and noise-level data sets, and is displayed in accordance with the legend. Some designers use the signal-to-noise ratio as a coverage quality indicator and define the boundary of coverage as all areas that have a signal-to-noise value above a certain threshold, such as 25 dB.
4-26
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Display Mode: Multiple Factor Split Screen
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-28
Here the split-screen mode is shown, in which four different views can simultaneously be displayed. This mode allows very easy visual comparison of the different measurement factors.
Copyright © 2004, Cisco Systems, Inc.
Using the Air Magnet Site Survey Tool for a Manual Survey
4-27
Manual Survey Situations and Obstacles Site survey engineers must consider the wide variety of situations that they will encounter when performing a manual site survey. This topic discusses some of the more common situations and obstacles that they will face.
Effects of Building Structure
There is a large variation in propagation properties across different materials. Attenuation through various standard materials varies from 2 dB per layer up to 20 dB. High attenuation might also mean good reflection of primary beam(for example, dropceiling grid).
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-29
Site survey engineers will find significant variation in propagation properties across different materials. This variation affects the wireless signal, because attenuation through various standard materials varies from 2 dB per layer up to 20 dB. High attenuation might also mean good reflection of a primary beam (for example, a drop-ceiling grid).
4-28
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Effects of Human Body Effects of people: Can be very significant: saltwater attenuation Do survey measurements during peak traffic times
Effects of body position on the tested device: Altitude Orientation Hand position on or around the device Check in standard user position, orientation
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-30
The site survey engineer will also need to survey measurements during peak traffic times to account for saltwater attenuation in people, which can be significant. Even the body position of the engineer can have an effect on the tested device. Site survey engineers should note their own altitude, orientation, and hand position in relation to the tested device. They should perform surveys while holding the test device in the same position as the user will hold it.
Copyright © 2004, Cisco Systems, Inc.
Using the Air Magnet Site Survey Tool for a Manual Survey
4-29
Coverage Mistakes Not enough overlap between cells = gaps
X
© 2004 Cisco Systems, Inc. All rights reserved.
Too much overlap between cells = performance problems
X
CAWSS 4.04-31
Basic coverage mistakes involve not having enough overlap between cells, which leads to gaps in the signal, and having too much overlap between cells, which leads to performance problems.
4-30
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Correcting Coverage Mistakes If you need more than two access points to cover your site: PLEASE PERFORM A SITE SURVEY Clearly specify overlap and fringe boundary parameters; verify with two access points during survey. Always verify coverage mapping after the installation and make any necessary adjustments. © 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-32
If more than two access points are needed to cover the site, it is strongly recommended that the engineer perform a site survey. The engineer must clearly specify overlap and fringe boundary parameters and verify with two access points during the survey. It is important to verify coverage mapping after the installation and make any necessary adjustments.
Copyright © 2004, Cisco Systems, Inc.
Using the Air Magnet Site Survey Tool for a Manual Survey
4-31
Defective Radios or Antennas Client with good radio (-90 dBm), good antenna (internal, diversity, high altitude). Coverage looks like this:
© 2004 Cisco Systems, Inc. All rights reserved.
Client with defective radio, poor or no antenna. Coverage looks like this: User will monopolize the bandwidth with excessive retries.
CAWSS 4.04-33
A client with a good radio (-90 dBm) and a good antenna (internal, diversity, high altitude) will have much better coverage than a client with a defective radio and a poor-quality or no antenna. A client with a defective radio and a poor-quality or no antenna will monopolize the bandwidth with excessive retries and restrict the access to the WLAN for clients with good radios.
4-32
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Correcting for Defective Radios or Antennas Inventory devices on your corporate WLAN to find defective devices and shut them down. Set standards and policies for acceptable devices. Get a wireless LAN analyzer, or sniffer to diagnose and resolve this problem.
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-34
Engineers must inventory devices on the corporate WLAN to find defective devices and shut them down. Then they must set standards and policies for acceptable devices and use a WLAN analyzer, or sniffer, to diagnose and resolve the problem.
Copyright © 2004, Cisco Systems, Inc.
Using the Air Magnet Site Survey Tool for a Manual Survey
4-33
Access Point Configuration Problems Incorrect data rate Tx power: not set properly Antenna diversity: is not on Antenna diversity: is on, but only one antenna is connected Channel: is not set correctly IP assignment: manual or DHCP is not working
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-35
The following are some of the major problems that can occur in an access point RF configuration: The data rate is incorrect. The transmit (Tx) power is not set properly. The antenna diversity is not on, or perhaps it is on but only one antenna is attached. The channel is not set correctly. The IP assignment is set to manual, or DHCP is not working.
4-34
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Correcting Access Point Configuration Problems Do not just turn on access point and hope for the best. Explore and understand the access point configuration options. Stage all the access points before final installation. Set up all parameters and label devices, and use monitoring tools if possible. Set up appropriate access control: restrict unauthorized access to access points. Clearly document your network. © 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-36
When engineers discover access point configuration problems, they should not just turn on the access point and hope for the best. The engineer must follow these access point configuration guidelines: Stage all the access points before final installation. Set up all parameters and label devices, and use monitoring tools if possible. Set up appropriate access control: restrict unauthorized access to access points. Clearly document the network.
Copyright © 2004, Cisco Systems, Inc.
Using the Air Magnet Site Survey Tool for a Manual Survey
4-35
Mysterious Dead Zones It used to work here; now it does not. It works only during certain times. It works only in certain locations now.
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-37
Mysterious dead zones can appear over time if physical environments change around the access points.
4-36
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Correcting for Mysterious Dead Zones Have walls moved? Cubicles? New MRI scanner installed? Recheck coverage against original maps. Develop change management protocol with facilities personnel. Physically examine all equipment. Are the antennas still there? Anything stacked on top of the access points? Interference? Did someone install other access points or RF-emitting devices? Security policies? Someone causing trouble?
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-38
There are a number of possible causes for the mysterious dead zones. The site survey engineer needs to get answers to these questions: Have walls moved? Cubicles? Has a new MRI scanner been installed? The engineer should recheck coverage against original maps and develop a change management protocol with facilities personnel. Engineers should also physically examine all equipment and determine if the antennas are still there and if anything is stacked on top of the access points. They should check for interference. If there is interference, they should see if someone installed other access points or RF-emitting devices. Finally, the engineer needs to consider security policies. It may be that someone is purposefully causing trouble.
Copyright © 2004, Cisco Systems, Inc.
Using the Air Magnet Site Survey Tool for a Manual Survey
4-37
References
Airmagnet Site Survey Application Note http://www.airmagnet.com/assets/Site.Survey.pdf
© 2004 Cisco Systems, Inc. All rights reserved.
4-38
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
CAWSS 4.04-39
Copyright © 2004, Cisco Systems, Inc.
Summary This topic summarizes the key points discussed in this module.
Summary DSA coverage audit AirMagnet site survey tool Common manual site survey situations and obstacles
© 2004 Cisco Systems, Inc. All rights reserved.
Copyright © 2004, Cisco Systems, Inc.
CAWSS 4.04-40
Using the Air Magnet Site Survey Tool for a Manual Survey
4-39
Review Questions Use the practice items here to review what you have learned in this module.
Review Questions Which display modes are useful in determining an actual test access point coverage boundary? There are many configuration parameters on the client that need to be matched with the installed access point. For survey purposes which parameters are the most essential? There are several filters that could be applied to the collected data. When would it be necessary to apply a channel filter in the display mode? When you are performing the actual survey, and walking a path inside a building to measure coverage from a test access point, what is NOT a recommended data collection practice?
© 2004 Cisco Systems, Inc. All rights reserved.
4-40
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
CAWSS 4.04-41
Copyright © 2004, Cisco Systems, Inc.
Module 5
Assisted Site Survey Techniques Overview This module explores the equipment and procedures that are used in an assisted site survey.
Module Objectives Upon completing this module, you will be able to complete the objectives shown in the figure.
Objectives Identify the required components for implementing assisted site surveys Identify the steps to effectively run an assisted site survey, including how to ensure optimal WLAN coverage Determine the quantity of coverage neccessary and where to place access points for use with the assisted site survey tool Identify the steps for final testing
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-2
Module Outline The outline lists the components of this module.
Outline Overview Introduction to Assisted Site Survey Technologies Required Cisco Products Density Testing Access Point Radio Scans Client Walkabout Final Testing Summary Review Questions © 2004 Cisco Systems, Inc. All rights reserved.
5-2
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
CAWSS 4.04-3
Copyright © 2004, Cisco Systems, Inc.
Introduction to Assisted Site Survey Technologies This topic introduces the benefits of the Cisco Structured Wireless-Aware Network (SWAN).
Cisco Structured Wireless-Aware Network Solution Benefits Deployment
Optimized deployment of high-performance access points: assisted site survey, live RF* readings
Management
Simplified, automated air and RF operation of a few hundreds to thousands of central or remotely located access points (configurations, firmware, coverage, interference, etc.)
Security
Wi-Fi Protected Access for access control, authentication, and data privacy, integrated WLAN IDS functionality, rogue access point detection and suppression
Flexibility
Future switch and router enhancements for scalability, familiar interface, fast and secure Layer 3 roaming and integrated wired and wireless LAN services
Support
Cisco warranties, support services, and partnerships like Cisco Compatible Extensions Program * RF = data transmissions through the air
© 2004 Cisco Systems, Inc. All rights reserved.
Copyright © 2004, Cisco Systems, Inc.
CAWSS 4.04-4
Assisted Site Survey Techniques
5-3
Cisco SWAN Air and RF Management Overview Si Si
NMS
Si Si
Si
WLSE 1. Clients and access points send their RM to the WDS access point. 2. WDS access point uses RM-Agg to condense and digest the RM into a set of small messages and sends it to the Cisco Works WLSE.
Network Core Si Si
Si
Distribution
RM-Agg
Access
RM
RM
WDS AP
Rogue AP 2.4GHz Phone RM
RM
RM
RM
CAWSS 4.04-5
© 2004 Cisco Systems, Inc. All rights reserved.
In this example, the following activity is taking place: Client scanning allows a rogue to be reported that is outside the Basic Service Set (BSS) of an infrastructure access point. Non-802.11 interference from a 2.4-GHz phone is detected as a mobile client roams throughout the network. Infrastructure access points are also monitoring radio frequency (RF) and reporting data that they collect to the Wireless Domain Services (WDS) access point. All data is aggregated by the WDS access point and sent to the CiscoWorks Wireless LAN Solution Engine (WLSE) for reporting and visualization. Wireless communication between clients and access points is based on Datagram Delivery Protocol (DDP); Wireless LAN Context Control Protocol (WLCCP) is used as the communication method between the wired infrastructure devices. The WDS minimizes the amount of traffic sent to the Cisco Works WLSE by acting as an aggregation point for data being provided by access points and client radios. WDS access point support for up to 30 infrastructure access points Fast, secure roaminguser security credentials cached in the WDS access point Local authentication servicesWAN link remote site survivability Radio Management (RM) Aggregationas infrastructure access points and scanning clients gather RF data, the WDS access point collects this data to be aggregated and sent to Cisco Works WLSE for reporting
5-4
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Assisted Site Survey Benefits
Functions as a deployment and operational tool for optimizing RF configuration Uses two innovative methods to characterize the RF environment: Access point radio scan Client walkabout Features radio parameter generation for processing of RF data Can be performed via a Cisco Works WLSE wizard, if desired CAWSS 4.04-6
© 2004 Cisco Systems, Inc. All rights reserved.
The figure lists some of the benefits of an assisted site survey.
Copyright © 2004, Cisco Systems, Inc.
Assisted Site Survey Techniques
5-5
Required Cisco Products This topic lists the Cisco products that are required for performing Cisco Structured WirelessAware Network functions such as fast, secure roaming, local authentication, and RM.
Cisco SWAN Three Elements Fast Fast Secure Secure L3 L3 Mobility Mobility Centralized Centralized Policies Policies High Availability High Availability
2
3
Cisco switches and routers with wireless-aware Cisco IOS® Software
Cisco Aironet client cards Cisco Compatible client devices
Expanded Expanded security security options options Granular Granular Site Site Surveys Surveys
CiscoWorks WLSE Cisco Aironet Access Points with 802.11 b, g, or a radios Wi-Fi certified client adapters 802.1X AAA Server
1
© 2004 Cisco Systems, Inc. All rights reserved.
Simplified Simplified Deployment/Mgmt Deployment/Mgmt Rogue Rogue AP AP Detection Detection and and Suppression Suppression
7 CAWSS 4.04-7
CiscoWorks Wireless LAN Solution Engine
Radio management
Network management
Intrusion detection capabilities
Radio-aware Cisco IOS software for Cisco multifunction access points
Cisco IOS software version 12.2 (11) JA and later Fast secure roaming Local authentication servicesWAN link remote site survivability
Cisco IOS software version 12.2 (13) JA and later Radio management capabilities
Future radio-aware Cisco IOS software versions Supported on switching and routing platforms Extended scalability Fast secure roaming
Cisco multifunction access points
5-6
1200 Series, 1100 Series platforms support wireless domain services
350 Series platforms running Cisco IOS software software can participate in Cisco SWAN
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Wireless clients
Wi-Fi certified clients for basic functionality
For expanded security option and granular site surveys Cisco clients running 5.30.17 and later Cisco Compatible Extensions version 2 clients
Copyright © 2004, Cisco Systems, Inc.
Assisted Site Survey Techniques
5-7
Density Testing This topic discusses the determinations that the engineer must make for density testing.
Density Testing for Assisted Site Surveys Determine the maximum number of users that will be on one access point (25 in this case).
Coverage at 11 MB, 100 mW
Warehouse: 25 Users Total
Yagi Antenna
Determine if a single access point can cover the 25 user locations. Separately evaluate, meeting rooms and locations where groups gather.
Required call size for 25 users Office Complex © 2004 Cisco Systems, Inc. All rights reserved.
Conference Rooms CAWSS 4.04-9
In conducting density testing, engineers must determine the area (using the floor plan) that will cover 25 users. They should separate out the areas where users gather, such as conference rooms, lunchrooms, and so on, because these areas require a higher number of access points to provide the ratio of users to access points that are specified in the design. You can install an access point as a typical location (or locations if there are different types of environments) and perform a manual site survey. You must determine if the cell size of the maximum power setting and minimum data rate will provide more coverage than is required, based on the assessment of the ratio of users to access points, as noted on the floor plan.
5-8
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Placing Access Points for an Assisted Site Survey If the cell size of a fullpowered access point is larger than what is determined as the cell size to maintain the user-to-access-point ratio (from the network design), then the assisted site survey can be used to complete that area. Place access points according to the floor plan as shown. Smaller cell defined because of more users in conference rooms © 2004 Cisco Systems, Inc. All rights reserved.
Coverage at 11 MB, 100 mW
Warehouse: 25 Users Total
Office Complex
Yagi Antenna
Conference Rooms CAWSS 4.04-10
Once the engineer has determined that the cell size of a full-powered access point, at the defined minimum data rate, is greater than is needed to provide coverage for the maximum number of users for a single access point, the floor plan can be used to determine locations for the access points. Some areas (such as conference rooms) will use a smaller cell size to maintain the proper ratio of users to access points. Once the access points have been placed, the assisted site survey can begin.
Copyright © 2004, Cisco Systems, Inc.
Assisted Site Survey Techniques
5-9
Some Areas May Require Manual Surveys If the cell size of a full-powered access point does not cover the required number of users, or an unusual pattern for antenna coverage Patch is required, a manual site survey Antenna will provide a better cost for the network by using fewer access points.
Coverage at 11 MB, 100 mW
Warehouse: 25 Users Total
Yagi Antenna
Omni Antennas
Conference Rooms © 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-11
If there are areas for which the maximum power, and minimum cell size, is insufficient to provide coverage for the proposed ratio of users to access points, then a manual site survey will provide a better cost for the network. A manual survey will permit more accurate cell sizing and antenna selection, and accurately provide coverage while using the minimum number of access points. If there are areas that use unusual antennas (like the Yagi), then a manual site survey provides better guarantees for coverage in certain areas.
5-10
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Access Point Radio Scans This topic discusses access point radio scans, and when and how they should be run.
Creating New Access Point Radio Scan
Maximum Tx power will be set only to the maximum allowed per country regulations
CAWSS 4.04-12
© 2004 Cisco Systems, Inc. All rights reserved.
An engineer should run an access point radio scan in the following situations: During initial setup After adding, deleting, or moving access points Periodically to capture any changes made to the access points The engineer can create multiple scan jobs, but only one job can be run at a time. Note
A running scan job temporarily degrades wireless LAN (WLAN) service, which might affect client associations. To minimize any disruption, schedule scan jobs to run during off hours.
Note
Your login credentials determine whether you can use the access point radio scan option.
In order to execute the access point radio scan, configure the maximum transmit (Tx) power (default is 100 mW), select the access points to participate in the scan, and schedule the job. Note
The maximum Tx power will be set only to the maximum allowed per the regulations of each individual country and will be controlled by the access point. Thus, if you begin a scan job at a maximum Tx power that is above the allowed threshold by your country, only the allowed maximum will be transmitted.
Copyright © 2004, Cisco Systems, Inc.
Assisted Site Survey Techniques
5-11
Selecting Access Points
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-13
To select access points as part of the access point radio scan procedure, follow these steps:
5-12
Step 1
Click Select AP. All managed devices are listed in the Device Selector in the middle pane.
Step 2
Choose the devices that are needed for the job.
Step 3
From the menu in the left pane, go to the next step, Schedule Job.
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Creating a Scan Job
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-14
To continue the access point radio scan procedure by creating a scan job, follow these steps: Step 1
Click Schedule Job.
Step 2
Click Run Now to run the job.
Note
This option ignores all of the other scheduling options (Start Date, Start Time, and Repeat). To use the Start Date option, choose the month, day, and year that you want your job to run. To use the Start Time option, choose the hour and minute of the day that you want your job to run. Check the Enable check box to run the job repeatedly. To indicate how often you want the job to repeat by using the Repeat every option, choose an interval of time: hours, days, weeks, or months.
Note
Choosing the Repeat every option runs the job periodically, starting with the date and time that you entered as part of the Start Date and Start Time options.
Step 3
From the menu in the left pane, choose the next task, Finish. The job will run immediately.
Copyright © 2004, Cisco Systems, Inc.
Assisted Site Survey Techniques
5-13
Viewing a Scheduled Scan Job
CAWSS 4.04-15
© 2004 Cisco Systems, Inc. All rights reserved.
To view the run logs for a selected job, follow these steps: Note
Your login credentials determine whether you can use this option.
Step 1
Select Radio Manager > AP Radio Scan.
Step 2
From the All AP Radio Scan Jobs table, choose a job and then click Job Run Log.
The Job Runs table appears in a separate browser window. This table contains the following information for each run: Field description Select Run buttonChoose this button to see the details for that run. The details for the selected job run appear below the list of runs for that job: Job Start Timethe time that the job started Job End Timethe time that the job ended Job Statusthe status of the job Percent Completethe percent of the job that has been completed The Job Runs table also provides the following options: To sort table data, click the corresponding heading (see Sorting Table Data). To view the details for a different job run, choose another run and click Job Run Log. The details for the selected run appear below the list of runs. To view the access point location information that was collected during a job run, choose the run and click AP Location Information. Note
5-14
Access point location information is available only for the most recently completed access point radio scan job.
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
The AP Location Information table contains the following information: Field description AP Namethe name of the access point IP Addressthe IP address for that access point Has Scan Dataindication of whether scan data was collected for this access point (YES or NO) Neighborsthe number of neighboring access points that have been detected Last Scan Timethe date and time that this scan was run Step 3
To refresh the table, click Refresh.
Copyright © 2004, Cisco Systems, Inc.
Assisted Site Survey Techniques
5-15
Access Point Radio Scan Job Run Log
1. Maximum power threshold is userconfigurable. 2. All selected radio-scan-capable access points will participate.
3. Access points will begin at maximum power and step down. 4. Success message notifies when scan is complete. CAWSS 4.04-16
© 2004 Cisco Systems, Inc. All rights reserved.
You can refresh the job log at anytime to see the latest status of a job. If you have made recent changes to one or more access point radio scan jobs, you can refresh the job list to see the latest information. Follow these steps: Note
5-16
Your login credentials determine whether you can use this option.
Step 1
Choose Radio Manager > AP Radio Scan. The list of access point radio scan jobs appears.
Step 2
From the Job State list, choose the type of job that you want to view.
Step 3
Click Refresh. The screen shows an updated list of the currently displayed jobs.
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Assisted Site Survey Wizard
Launchable from Location Manager within WLSE Includes details about access point selection, access point scan, client walkabout, and radio parameter generation
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-17
Assisted Site Survey Wizard includes details about access point selection, whether this is a new access point radio scan or a scan using old data from a previous scan; the maximum Tx power for the access point radio scan; the number of client and MAC addresses for the clients participating in the walkabout; and radio parameter generation details, including the enabling of black hole mitigation, the channels to be used, and details regarding how many clients are expected per access point.
Copyright © 2004, Cisco Systems, Inc.
Assisted Site Survey Techniques
5-17
Viewing Site Survey Wizard Jobs
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-18
The procedure for viewing Assisted Site Survey Wizard jobs is similar to that for viewing jobs for the access point radio scan except that the job pertains to running the wizard.
5-18
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Viewing Site Survey Wizard Jobs (Cont.)
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-19
Here is an example of the view that is used to look at the details of a job. The parameters have been successfully applied to each selected access point, and the provided details illustrate the changes that were made, including changes to the Tx power setting and the beacon intervals (in milliseconds).
Copyright © 2004, Cisco Systems, Inc.
Assisted Site Survey Techniques
5-19
Client Walkabout Although the client walkabout is not a required component of the assisted site survey, it is recommended because it allows a gathering of additional RF data. This topic discusses the client walkabout.
Client Walkabout Additional step of assisted site survey Allows for gathering of additional RF data
© 2004 Cisco Systems, Inc. All rights reserved.
5-20
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
CAWSS 4.04-20
Copyright © 2004, Cisco Systems, Inc.
Creating a New Client Walkabout Job
CAWSS 4.04-21
© 2004 Cisco Systems, Inc. All rights reserved.
The engineer can use the Client Walkabout option to create a client walkabout session. Note
Your login credentials determine whether you can use this option.
Before running a client walkabout, the engineer must have performed the following tasks: Discovered the devices Made the devices managed Authenticated the devices with WDS Configured the walkabout client to associate with the access points that have been selected for the walkabout To create a new client walkabout job, follow these steps: Step 1
Choose Radio Manager > Client Walkabout.
Step 2
Click New.
The window refreshes with the Client Walkabout menu in the left pane and the Client Walkabout Name dialog box in the right pane. Step 3
Choose the following numbered choices in the left pane to create a client walkabout: Name Select APs Enter Client MAC Options
Note Step 4
All these steps must be completed but do not have to be done in order.
Click Finish.
Copyright © 2004, Cisco Systems, Inc.
Assisted Site Survey Techniques
5-21
Caution
5-22
Clicking on any subtab before you have saved your entries in the Job Creation window will reset the window, and you will lose all the information that you have entered.
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Viewing a Scheduled Client Walkabout Job
CAWSS 4.04-22
© 2004 Cisco Systems, Inc. All rights reserved.
The engineer can use this screen to view client walkabout sessions. Note
Your login credentials determine whether you can use this option.
To view a scheduled client walkabout job, follow these steps: Step 1
Choose Radio Manager > Client Walkabout.
Step 2
From the Client Walkabout State list, choose the type of walkabout whose status you want to check (Running or All). The window refreshes, and the walkabouts are displayed. The resulting table contains the follow information: Field description Namethe client walkabout name Statusthe status of the walkabout Last Run Startedthe time that the last run of this client walkabout was started Last Run Stoppedthe time that the last run of this client walkabout was stopped Ownerthe user who last edited the job
Step 3
To sort table data, click the corresponding heading.
Step 4
From this window, you can: Edit a walkabout Delete a walkabout Start a walkabout Stop a walkabout View walkabout run details View the access point locations that were collected during a walkabout Refresh the screen
Copyright © 2004, Cisco Systems, Inc.
Assisted Site Survey Techniques
5-23
Selecting Clients to Participate
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-23
After the access points have been selected to participate in the scan, the engineer can use the screen shown here to choose clients to participate in the walkabout (up to five clients at a time).
5-24
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Configuring Additional Options
CAWSS 4.04-24
© 2004 Cisco Systems, Inc. All rights reserved.
During a walkabout, the Tx power in the access points is increased so that the power that is required to cover the edges of the WLAN can be determined. The engineer can use this option to reset the maximum Tx power level that is used by the access points. To configure additional client walkabout options, follow these steps: Step 1
Click Options.
Step 2
Choose the desired AP Power Setting option.
Note
Step 3
By default, the power level is set to the maximum value that is allowed on the access point or the maximum that is allowed by the regulatory domain. The engineer might choose to enter a lower power setting when, for example, the default power level might affect a neighboring network.
From the menu in the left pane, choose the next task, Finish.
Copyright © 2004, Cisco Systems, Inc.
Assisted Site Survey Techniques
5-25
Viewing a Scheduled Client Walkabout Job
CAWSS 4.04-25
© 2004 Cisco Systems, Inc. All rights reserved.
The engineer can use this option to view the details of a client walkabout session. Note
Your login credentials determine whether you can use this option.
To view the details of a scheduled client walkabout job, follow these steps: Step 1
Choose Radio Manager > Client Walkabout.
Step 2
Choose a walkabout and then click Detailed.
Step 3
The Client Walkabout Details window shows the following information: Field description Namename of the walkabout Descriptionwalkabout description, if any Power Modeaccess point power setting that has been selected for the walkabout Max. Powerthe value of the access point power setting (this field is populated only if the entered value is in Use No More Than __ mW) Selected APsnames of the access point devices selected for the walkabout Client MAC Addressthe list of client MAC addresses to be used during the walkabout Statusthe status of the walkabout Last Run Startedthe time that the last run of this client walkabout was started Last Run Stoppedthe time that the last run of this client walkabout was stopped
5-26
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Assisted Site Survey Wizard Client Walkabout
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-26
This screen illustrates the view that you would see if you were running the client walkabout through the Assisted Site Survey Wizard, as opposed to running it from the Radio Manager tab manually.
Copyright © 2004, Cisco Systems, Inc.
Assisted Site Survey Techniques
5-27
Final Testing This topic discusses the tools and reports that are used for final testing to confirm optimal RF coverage.
Tools for Confirming Optimal RF Coverage The Cisco ACU site survey tool can be used to confirm RF coverage. CiscoWorks WLSE has coverage display and reporting tools available. A wireless sniffer can also be used to confirm RF coverage.
© 2004 Cisco Systems, Inc. All rights reserved.
5-28
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
CAWSS 4.04-27
Copyright © 2004, Cisco Systems, Inc.
Radio Management Application Features CiscoWorks WLSE Tools for Radio Management
Location Manager
Radio Network Reports © 2004 Cisco Systems, Inc. All rights reserved.
Assisted Site Survey
Rogue AP Detection
Radio Interference Detection CAWSS 4.04-28
There are several additional tools available within Cisco Works WLSE for ensuring that the parameters set in the WLAN are accurate and the most effective ones to use. For example, some of these tools are Location Manager, the Assisted Site Survey Wizard, and tools for viewing and managing rogue access points, viewing detailed reports related to RM, and monitoring interference detection.
Copyright © 2004, Cisco Systems, Inc.
Assisted Site Survey Techniques
5-29
Location Manager
2-D radio visualization Infrastructure access point management Cell size, channel and power settings, and other radio parameters © 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-29
Location Manager is a Java-based (version 1.4.1) tool that is launchable from the Radio Management tab or the Fault screen. It provides 2-D visualization of infrastructure access points and their coverage (power and channel settings and throughput), and rogue access point location. With Location Manager, users can import their floor plan using .jpg, .gif, or .png formats (other formats can be converted to one of the supported formats), create floors and complete buildings, and, with the help of such tools as the ruler tool, place access points in approximate locations based on floor dimensions.
5-30
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Radio Network Reports Radio configuration inventory style reports Key reports that help users understand the characteristics of the RF environment: Path loss between access points Channel loading
CAWSS 4.04-30
© 2004 Cisco Systems, Inc. All rights reserved.
There are a number of reports available within Cisco Works WLSE. With the Cisco Works WLSE v2.5 release, a few new reports have been introduced related to RM, including a report that lets users view the path loss between selected access points and examine channel loading. This information is useful for ensuring that parameters have been accurately set. If they seem inaccurate, it is recommended that you rerun the access point radio scan and client walkabout (optional). The Radio Network Reports window allows the user to view RM information. The user can view, export, and e-mail the reports. Using this option, it is possible to view the following types of RM reports: Configured Radio Parameters Report (11b) Path Loss Between Managed APs Report (11b) Channel Loading Report (11b) The folders and devices in the Device Selector display icons indicating the alarm status of the devices. Note
Your login credentials determine whether you can use this option.
Copyright © 2004, Cisco Systems, Inc.
Assisted Site Survey Techniques
5-31
Displaying a Configured Radio Parameters Report (11b) To display the Configured Radio Parameters Report (11b), follow these steps: Step 1
Choose Reports > Radio Manager. The window refreshes with the Device Selector in the left pane.
Step 2
From the Device Selector, click to expand the folder for the group of reports that you want to view. The right pane refreshes.
Step 3
From the Report Name list, choose Configured Radio Parameters Report (11b).
Step 4
Click View. A report with the following information is displayed: Table 6-6 Configured Radio Parameters Report (11b) Column Description AP Namethe name of the access point Interface Namethe name of the radio interface MAC Addressthe MAC address of the access point PHYthe physical interface type (11b) Channelthe radio channel that is being used Transmit Powerthe power level of the radio transmission in mW Data Ratethe data rate in Mbps Beaconthe amount of time between beacons in kilomicroseconds Admin Statusthe administrative status of the access point Operational Statusthe operational status of the access point As Ofthe time at which the Cisco Works WLSE polled information from the device
Step 5
To export the report, click Export.
Step 6
To e-mail the report, click Email Report.
Displaying a Path Loss Between Managed APs Report (11b) To display the Displaying a Path Loss Between Managed APs Report (11b), follow these steps: Step 1
Choose Reports > Radio Manager. The window refreshes with the Device Selector in the left pane.
Step 2
From the Device Selector, click to expand the folder for the group of reports that you want to view. The right pane refreshes.
Step 3
From the Report Name list, choose Path Loss Between Managed APs Report (11b).
Step 4
Click View. A report with the following information is displayed: Table 6-7 Path Loss Between Managed APs Report (11b) Column Description AP Namethe name of the access point Interface Namethe name of the radio interface PHYthe physical interface type (11b)
5-32
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Channelthe radio channel that is being used Neighbor AP Namethe name of the neighbor access point Neighbor Interface Namethe interface name of the neighbor access point Path Lossthe amount in decibels of path loss between the two access points As Ofthe time at which the Cisco Works WLSE polled information from the device Step 5
To export the report, click Export.
Step 6
To e-mail the report, click Email Report.
Displaying a Channel Loading Report (11b) To display the Channel Loading Report (11b), follow these steps: Step 1
Choose Reports > Radio Manager. The window refreshes with a Device Selector in the left pane.
Step 2
From the Device Selector, click to expand the folder for the group of reports that you want to view. The right pane refreshes.
Step 3
From the Report Name list, choose Channel Loading Report (11b).
Step 4
Click View. A report with the following information is displayed: Table 6-8 Channel Loading Report (11b) Column Description AP Namethe name of the access point PHYthe physical interface type (11b) Channelthe radio channel that is being used Average Near (%)the average (of 15 minutes) channel loading that was detected by the access point from the nearest clients Average Far (%)the average (of 15 minutes) channel loading that was detected by the access point from the farthest clients Peak Near (%)The average (of 15 minutes) peak value that was detected by the access point from the nearest clients Peak Far (%)The average (of 15 minutes) peak value that was detected by the access point from the farthest clients As Ofthe time at which the Cisco Works WLSE polled information from the device
Step 5
To export the report, click Export.
Step 6
To e-mail the report, click Email Report.
Copyright © 2004, Cisco Systems, Inc.
Assisted Site Survey Techniques
5-33
Non-802.11 Interference Detection Customizable noise floor threshold Fault generated when non-802.11 interference detected Critical to understanding interference that degrades WLAN performance
CAWSS 4.04-31
© 2004 Cisco Systems, Inc. All rights reserved.
Policies and thresholds can be set for generating faults, should any non-802.11 interference be detected. This capability is important because interference can negatively affect the WLAN. The engineer can use this option to set the threshold condition for interference detection. When the condition is met, a fault is generated and can be viewed under Faults > Display Faults. To set the threshold condition for interference detection, follow these steps: Step 1
Choose Faults > Manage Network-Wide Settings > Interference Detection.
Step 2
Complete the following fields: EnableCheck the check box to enable the setting. DegradedChoose the severity level, the interference level, the percentage, and the time interval before the status is degraded. OKChoose the interference level, the percentage, and the time interval before the status is determined to be OK.
Step 3
5-34
Click Reset to refresh any fields that have been changed but now must be restored, or click Apply to set the new entries.
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Testing Benefits Access point radio scan
Gathers RF data based on setting selected access points to same channel and maximum power threshold
Client walkabout
Allows collection of additional data beyond that of access point radio scan
Density testing
Provides a means of effective planning for RF coverage based on the location, number of users, and bandwidth requirements
Final Testing
Provides additional tools for ensuring the accuracy of RF settings
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-32
As this figure indicates, there are benefits to all kinds of testing, including final testing.
Copyright © 2004, Cisco Systems, Inc.
Assisted Site Survey Techniques
5-35
Summary This topic summarizes the key points discussed in this module.
Summary Required components for implementing assisted site surveys Steps to run an assisted site survey effectively, including how to ensure optimal WLAN coverage Quantity of coverage that is needed and where to place access points for use with the assisted site survey tool Steps for final testing
© 2004 Cisco Systems, Inc. All rights reserved.
5-36
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
CAWSS 4.04-33
Copyright © 2004, Cisco Systems, Inc.
Review Questions Use the practice items here to review what you have learned in this module.
Review Questions What are the major components for running an assisted site survey? What is the CiscoWorks Wireless LAN Solution Engine (WLSE)? What part in the automated site survey process does WLSE play? What is the difference between the access point radio scan and client walkabout? What tools are available in the final testing stage to confirm optimal RF coverage?
© 2004 Cisco Systems, Inc. All rights reserved.
Copyright © 2004, Cisco Systems, Inc.
CAWSS 4.04-34
Assisted Site Survey Techniques
5-37
5-38
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Module 6
WLAN Design Considerations Overview This module explores the many wireless LAN (WLAN) design considerations that the engineer must keep in mind while performing the site survey and completing the site survey report.
Module Objectives Upon completing this module, you will be able to complete the objectives shown in the figure.
Objectives Describe network cabling that is associated with the WLAN installation Determine mounting requirements Describe a site survey document that can be used to obtain cabling quotes for an installation Make recommendations for equipment to be installed in plenum spaces
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-2
Module Outline The outline lists the components of this module.
Outline Overview LAN Infrastructure Cables and Connectors Plenum Firewalls Risers Mounting Securing the Access Point Splitters NEMA Enclosures Summary Review Questions © 2004 Cisco Systems, Inc. All rights reserved.
6-2
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
CAWSS 4.04-3
Copyright © 2004, Cisco Systems, Inc.
LAN Infrastructure IT professionals today are generally overworked and do not want any project that might increase their workload. When installing a WLAN, they will require a site survey. What they want is a site survey that provides in detail where the access points are to be located, how they will be mounted, how they will be connected to the network, and where any cabling or power may need to be installed. This topic discusses the need for a detailed site survey.
Installation Concerns IT personnel are already overworked and not looking to increase their workload. Customer expects a professional, detailed, all-inclusive site survey. A good site survey and report will lead to future business for your company.
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-4
With a detailed site survey report, the IT manager can turn the necessary portions over to a local contractor who can install the cabling that may be needed to provide the WLAN connectivity to the network. An important part of the preparations will be making sure that the customer network is ready for the upcoming installation. If the site survey engineer can save the IT manager a lot of work by providing an effective site survey, the customer will remember this fact when another site survey is needed.
Copyright © 2004, Cisco Systems, Inc.
WLAN Design Considerations
6-3
Installation Concerns Make customer aware of potential problems. Be proactive instead of reactive. Make the most of your chance to help the customer. Reputations win further business.
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-5
The engineer must try to identify potential problems upfront and discuss how these issues will be handled. If the customer is aware of these issues, they can be handled before the installation. The customer does not want to find out about problem issues during the installation, or during the go live period. By addressing potential problems and being proactive instead of reactive, the engineer can appear as the strong, reliable source during installation, instead of the weak link. The reputation of the engineering firm for site surveys is one of its strongest assets and should always be protected. One bad site survey can hurt the business of an engineering firm for months or years to come.
6-4
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Cable Awareness Media Copper versus fiber Access points provide copper connections only If the cable run exceeds the distance limitation for Fast Ethernet or if a fiber connection is desired, the Cisco Aironet Power Injector may be used Power Injector
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-6
The engineer should examine the media types that make up the network. The customer most likely uses some type of copper unshielded twisted pair (UTP) cabling for most of the runs. Copper can be run to a maximum distance of 328 feet (100 m) without a repeater or hub. Fiber can be run for miles if necessary. Some facilities use fiber cabling for their network backbone. Most of these sites use a combination of fiber and copper, with the fiber acting as the main backbone of the network and copper serving for runs to the desktop. In the event that the facility uses fiber cabling throughout, the engineer should make sure to advise the customer that the access points provide only RJ-45 (copper) connections and that a media transceiver or Cisco Aironet Power Injector is needed for each of the access points. These additions can represent a significant cost. The engineer should also keep in mind that media transceivers and Power Injectors are powered devices, and will require an outlet nearby.
Copyright © 2004, Cisco Systems, Inc.
WLAN Design Considerations
6-5
Cables and Connectors There are a variety of cables and connectors to recommend. This topic discusses the advantages and disadvantages of each type of cable and connector.
Antenna Extension Cables Antenna and access point location Cisco offers: LMR400-style cables 20 and 50 feet Total loss of 1.3 and 3.4 dB, respectively LMR600-style cables 100 and 150 feet Total loss of 4.4 and 6.6 dB, respectively
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-7
Sometimes the engineer may not be able to mount an antenna to the access point using the existing connecting cable. Use of these extension cables will result in signal loss. There is a loss of about 0.5 dB for every connection. For example, an antenna extension cable will have to be connected to the access point (0.5 dB loss) and to the antenna (0.5 dB loss). The use of this cable results in 1 decibel over isotropic (dBi) of loss without even considering loss through the cable itself. Current extension cables available with Cisco Aironet products are the LMR400 and LMR600. The LMR400 cable has a loss of 6.8 dB per 100 feet, and the LMR600 cable has a loss of 4.4 dB per 100 feet. The LMR400 cable is sold in 20- and 50-foot lengths. The LMR600 cable is sold in 100- and 150-foot lengths.
6-6
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Antenna Extension Cables and Loss Consider loss for cables and connectors. Use Category 5 cable to locate access points as close to antenna as possible. Cisco cable assemblies have RP-TNC plug and jack connectors installed. Custom-length and plenumrated cables available from third-party companies.
© 2004 Cisco Systems, Inc. All rights reserved.
LMR400
LMR600
CAWSS 4.04-8
Engineers should keep signal loss in mind if they are considering using an extension cable. It is not recommended that the 100-foot (30-m) extension cable be used with the Cisco Aironet 1200 Series products. There are virtually no indoor antennas that could sustain the amount of loss that is associated with the 100-foot cable and still be effective. Any antennas with less than 7 dBi of gain would be completely ineffective if used with the 150-foot cable. A better idea is to run Category 5 cable to the antenna location and mount the access point as close to the antenna as possible. In the event that an antenna extension cable is needed, you should use only as much cable as is absolutely necessary. Note
All Cisco antennas have 36 inches of plenum-rated cable. The Cisco extension cables are not plenum-rated. Some installations may require plenum-rated cable. If this is the case, you can acquire plenum-rated cable from third-party vendors such as Times Microwave Systems, located online at http://www.timesmicrowave.com.
Copyright © 2004, Cisco Systems, Inc.
WLAN Design Considerations
6-7
Antenna Attenuator
It can be difficult to carry one cable of each length Splitters, cables, and lightning arrestors add loss Duplicate the loss with a single device
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-9
Surveys should always be performed using the equipment that will eventually be installed. This goal can sometimes be difficult to achieve when you using splitters, lightning arrestors, and extension cables. Instead of carrying one of every length of cable, plus lightning arrestors, splitters, and other accessories, some engineers outfit the site survey kit with an antenna attenuator. The antenna attenuator allows them to inject varying amounts of loss without needing the actual accessories.
6-8
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
RP-TNC Connectors RP-TNC connectors are available from Cisco. RG58 cable should not be used for extension cables. N-style extension cables: Jumpers As much as 3.5-dBi loss © 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-10
Cisco offers the reverse-polarity threaded naval connector (RP-TNC) for the LMR400 and LMR600 cables. The engineer should not attempt to use RG58 cable for an extension cable. The amount of loss in this type of cable (19 dBi for 100 feet, or 30 m) makes it useless as an extension cable. RG58 connectors are available in case the original connector on an antenna is damaged and needs to be replaced. Most Cisco Aironet antenna connection cables are RG58. Some installers try to substitute extension cables with an N-style connector. These are widely available. An RG58 jumper is used to connect to the access point and antenna. Although the extension cables with the N-style connectors are more widely available, and possibly less expensive, this solution is not worthwhile in the long run. The jumper cables will have an RPTNC connector on one end and an N-style connector on the other. One jumper is needed for connection to the access point, and another for the antenna. This situation can result in a loss of 3.5 dBi or more. Another consideration is that access points and antennas should use RP-TNC connectors to meet Federal Communications Commission (FCC) regulations. All Cisco cable assemblies have RP-TNC plug and jack connectors installed. Note
Because the use of a connector other than an RP-TNC connector may violate FCC guidelines, the installer must verify compliance if using a different kind of connector.
Copyright © 2004, Cisco Systems, Inc.
WLAN Design Considerations
6-9
Plenum According to a definition from the National Electrical Code (NEC) 2001, plenum is a compartment or chamber to which one or more air ducts are connected and that forms part of the air distribution system. This topic discusses the special needs of plenum spaces.
Building Codes Plenum A compartment or chamber to which one or more air ducts are connected Forms part of the air distribution system Category 5 cable available in plenum and nonplenum Nonplenum sheath is PVC and gives off toxic fumes when melted
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-11
Commercial constructions often use suspended ceilings as return passages for environmental air. These plenum spaces have become convenient wiring locations for a variety of applications. However, use of these areas may pose a serious hazard in the event of a fire. Once the fire reaches the plenum space, few barriers exist to contain the smoke and flames. The National Fire Protection Association (NFPA) has recognized the potential for a hazard created by wire and cable in an environmental air space. Severe restrictions on cabling were included in the 1975 edition of the NEC. All subsequent NEC editions set forth safety requirements for flammable insulations. The NEC states that all cabling not in a conduit, and installed in plenum spaces, shall be listed as having adequate fire-resistant and low-smoke-producing characteristics. Building construction, as well as local and state building codes, determines which type of cabling must be used in plenum spaces. All other equipment that is installed (access points) must also be plenum-rated. Cisco Aironet Access Points, which are enclosed in a metal case, provide the required durability and plenum rating.
6-10
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Plenum Category 5 available: Plenum Nonplenum
Plenum areas: Egg-crate ceiling tiles No insulation Firewalls
Nonplenum areas use ducting in plenum for air return.
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-12
Category 5 cable is available as plenum and nonplenum cable. Plenum cables have a different sheath, which will not melt as easily as nonplenum and will not give off toxic fumes. Plenum cable is easily identified. The sheath of plenum cable is much thicker, stiffer, and harder to work with than standard Category 5 cable. The cable will also be marked with a code (CMP, for example, indicates a plenum-rated, unshielded cable). Make sure that antenna cabling and any antenna extension cables are plenum-rated if the access point will be mounted in a plenum area. Some easy ways to identify a plenum environment are the egg-crate ceiling tiles, a lack of insulation above the ceiling tiles, and firewalls. Some local and state building codes require plenum cable regardless of the environment. A nonplenum environment is one where the air return is ducted. When the air return is ducted, there is very little chance that the toxic fumes could spread in the event of a fire.
Copyright © 2004, Cisco Systems, Inc.
WLAN Design Considerations
6-11
Plenum (Cont.)
No chance for toxic fumes to get inside the ducting Nonplenum areas: Ductwork Lack of firewalls Insulation
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-13
In a nonplenum environment it may be suitable to use a generalpurpose, polyvinyl chloride (PVC) type of cabling. These cables will also have identifying codes (CM, for example, indicates a nonplenum, unshielded cable). Some indications of a nonplenum environment are an abundance of duct work above the ceiling tiles, a lack of firewalls, and insulation above the ceiling tiles.
6-12
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Firewalls Firewalls are usually easily identified. They are concrete, cinder-block, or brick structures that extend the full width of a room or passageway, and extend from floor to ceiling. There are no breaks in firewalls. Firewalls are designed to contain a fire to a specific area by acting as a barrier. This topic discusses firewall coverage issues.
Coverage Issues: Firewalls
Easily identified Act as barriers to contain fires Can limit the range of a 2.4-GHz signal Can completely stop 5-GHz signal
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-14
Because of their construction, firewalls typically hinder 2.4-GHz radio frequency (RF) signals and completely stop 5-GHz signals. The identification of firewalls before starting a survey can help the engineer design the WLAN around the RF obstacle.
Copyright © 2004, Cisco Systems, Inc.
WLAN Design Considerations
6-13
Firewalls Some firewalls may have doors. Fire doors can hamper the RF signal as well. Survey with doors closed. Survey with automatic fire doors open.
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-15
Many facilities have firewalls with doorways. The doors are specially constructed and sealed to withstand and contain a fire. Other than their heavy construction, these doors are not easily identified. If it is possible that a door or doors may be part of a firewall, the engineer should check and make sure. If they are, the engineer should survey with the doors closed. Closing the doors will have an effect on coverage. Just because the doors are open when the engineer is in the facility, the engineer should not assume that they will always be left open. Fire doors are supposed to remain closed (in case of fire) unless the WLAN system is also used for IP phones or security, and so on. Newer facilities (especially hospitals) may have automatic fire doors. These doors are held open magnetically and close automatically if the fire alarm is triggered. If the facility uses automatic fire doors, then perform the survey with the doors open.
6-14
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Risers Risers are often referred to as wiring closets. Risers are areas of the building where cabling, conduits, and plumbing may be run from floor to floor. Most often, risers are stacked on top of one another, making it easy to run the height of the building. This topic discusses the issues associated with risers.
Risers Sometimes referred to as wiring closets. Used for wiring between floors. Stacked on top of each other. Riser walls are firewalls. If a riser is plenum-rated, install only plenum-rated equipment.
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-16
All four walls of a riser act as firewalls, as well as the floor and ceiling. And like firewalls, there are standards for penetration. The engineer should make a note of risers for the same reasons as for firewalls. Risers will require penetrations that meet NEC standards, and will require plenum-rated equipment if the riser is plenum rated.
Copyright © 2004, Cisco Systems, Inc.
WLAN Design Considerations
6-15
Mounting Access point mounting varies with the type of access point, its use, and the specific solutions that can be used in a particular environment. This topic discusses the different ways to mount access points.
1200 Series Access Point Mounting
Mounting holes Mounting solutions: Concrete Drywall I beam Ceiling
Secure the access points
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-17
The access point can be mounted on any of the following surfaces: Horizontal or vertical flat surfaces, such as walls or ceilings Suspended ceilings The access point ships with a detachable mounting bracket and the necessary mounting hardware. Because it is detachable, the mounting bracket can be used as a template to mark the positions of the mounting holes for your installation. The engineer can then install the mounting bracket and attach the access point when ready. The figure shown here identifies the location of the mounting holes on the bracket.
6-16
Note
If you are mounting an access point with a 5-GHz radio in environmental air space, Cisco recommends that you mount the access point horizontally with its antennas pointing down. Doing so results in the access point complying with regulatory requirements for environmental air space.
Note
When mounting the access point in the environmental air space of a building, use Ethernet cable suitable for operation in such a space. Consult Section 300-22(C) of the NEC.
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Mounting on a Horizontal or Vertical Surface
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-18
To mount an access point on a horizontal or vertical surface, follow these steps: Step 1
Use the mounting bracket as a template to mark the locations of the four mounting holes.
Step 2
Drill one of the following sized holes at the locations that you marked: 3/16 in. (4.7 mm) if you are using wall anchors 1/8 in. (6.3 mm) if you are not using wall anchors
Step 3
Install the anchors into the wall if you are using them.
Step 4
Secure the mounting bracket to the surface using the fasteners.
Note Step 5
Note
On a vertical surface, mount the bracket with its security hasp facing down.
Attach the access point to the mounting bracket. (See information further in this lesson for attaching and securing the access point to the mounting bracket.) You can make the installation more secure by mounting it to a stud or major structural member and using the appropriate fasteners.
Copyright © 2004, Cisco Systems, Inc.
WLAN Design Considerations
6-17
Mounting on a Suspended Ceiling
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-19
To mount an access point on a suspended ceiling, follow these steps:
6-18
Step 1
Determine where to mount the access point.
Step 2
Attach two caddy fasteners to the suspended-ceiling T-rail.
Step 3
Use the mounting bracket to adjust the distance between the caddy fasteners so that they align with the holes in the mounting bracket.
Step 4
Use a standard screwdriver to tighten the caddy fastener studs in place on the suspended-ceiling T-rail. Do not overtighten.
Step 5
Install a plastic spacer on each caddy fastener stud. The spacer legs should contact the suspended-ceiling T-rail.
Step 6
Attach the mounting bracket to the caddy fastener studs and loosely install a nut on each stud.
Step 7
Use a wrench or pliers to tighten the nuts. Do not overtighten.
Step 8
Attach the access point to the mounting bracket. (See information further in this lesson for attaching and securing the access point to the mounting bracket.)
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Attaching the Access Point to the Mounting Bracket
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-20
To attach an access point to a mounting bracket, follow these steps: Step 1
Line up the three mounting pins on the access point with the large ends of the keyhole-shaped holes on the mounting bracket.
Step 2
Insert the access point into the keyhole-shaped holes and maintain a slight pressure to hold it in place.
Step 3
Slide the access point mounting pins into the small ends of the keyhole-shaped holes on the mounting bracket and push the connector end of the access point. There will be an audible click when the locking detent contacts the access point and locks it into place.
Step 4
Attach and adjust the antenna(s) or antenna cables.
Step 5
Connect the Ethernet cable to the Ethernet port of the access point.
Step 6
Insert the Cisco Aironet 1200 Series power module cable connector into the 48VDC power port of the access point (if using a local power source).
Copyright © 2004, Cisco Systems, Inc.
WLAN Design Considerations
6-19
Securing the Access Point The security hasp on the mounting bracket enables the engineer to lock the access point to the bracket to make it more secure. When the access point is properly installed on the mounting bracket, the holes in the security hasps line up so a padlock can be installed. (Known compatible padlocks are Master Lock models 120T or 121T.) This topic discusses the procedure for securing the access point.
Access Point Mounting
Do not cover access point lights. Mount upside down so Ethernet indicator lights can be seen from the floor. Label access points.
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-21
Mount the access point in what appears to be an upside-down position. This position allows the indicator lights for the Ethernet port to be seen from the floor. Whenever possible, you should label access points with the name, IP address, channel, and service set identifier (SSID). The letters need to be easily readable from the floor in the event that the access point requires troubleshooting. When surveying, the engineer should make sure and survey with the antennas in the position in which they will be mounted. There are different coverage patterns above and below the antenna. If the survey is done with the antenna in one position, and then the access point is mounted with the antenna in another position, the coverage may be different than expected.
6-20
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Antenna Mounting Some antennas not shipped with mounting brackets
Mast Mount
Modify brackets
Patch
Fit your needs Can be used with a variety of antennas Ceiling Mount © 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-22
Every access point will have an antenna attached to it. Most antennas are either shipped with a mounting bracket, or a mounting bracket is available as an option. The challenge is that most antennas are designed to be mounted in a certain way. A 5.2-dBi mast mount antenna is designed to be mounted to a mast and is shipped with the hardware to mount the antenna to a mast. Ingenuity may be required to mount the antenna to an I beam. Standoff brackets are available, but these are not designed to be mounted to an I beam either. Some installers use zip ties, beam clamps, or bolts to attach the standoff brackets to I beams and then mount the antenna to the bracket. If a mast mount antenna is to be used indoors, the engineer should make sure that it is mounted as shown in the figure. The antenna is intended for outdoor use and designed to be mounted with the metal sleeve on the bottom. For indoor use, the metal sleeve should be on top. Be creative. Modified brackets can be used for a variety of antennas. Note
5-GHz products using the Unlicensed National Information Infrastructure (UNII-1) band must also use nonremovable antennas.
Note
Cisco does not currently offer a product only for the UNII-2 band.
Caution
Any product that uses the UNII-1 and UNII-2 bands must abide by the rules for a UNII-1 product. The Cisco 5-GHz product uses both the UNII-1 and UNII-2 band, and therefore uses a nonremovable antenna.
Copyright © 2004, Cisco Systems, Inc.
WLAN Design Considerations
6-21
Antenna Mounting (Cont.) Solid and secure Do not hang antennas by their cable Cable can break or become damaged Antenna can sway and provide a moving cell
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-23
Just as with the access points, the engineer must always make sure that the antenna has a secure, solid mount. The engineer should ensure that the antenna will hang properly when mounted to the base. If the survey is performed with the antenna in a vertical orientation and it is then mounted to an insecure base, it may hang at an angle, changing the coverage pattern. Antennas should not be hung by their cable. The cable is not designed for this purpose and may eventually break or suffer internal damage that cannot be seen. Also, the antennas may sway when the air conditioning comes on, providing a moving coverage cell.
6-22
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Antenna Mounting (Cont.) Sometimes antennas are mounted in unusual ways. Specify in your report exactly how the antenna is to be mounted.
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-24
Sometimes antennas may be used or mounted in an unusual way. For example, in some circumstances, a Yagi antenna or patch antenna mounted very high and pointed straight down at the floor is the best solution. If the antenna is to be mounted in an unusual way, the engineer should make a note of it in the report. The installer may not understand the intent of the engineer and mount the antenna in accordance with its specifications, changing the coverage pattern.
Copyright © 2004, Cisco Systems, Inc.
WLAN Design Considerations
6-23
Splitters Splitters can be very useful if they are installed properly. But it is important to understand the ramifications of installing a splitter. This topic discusses those ramifications.
RF Splitters Understand losses attributable to RF splitters. Most use N-style connectors. RP-TNC splitters are available. Splitter attaches to access point and antennas using extension cable jumpers. Jumpers are LMR400 cables.
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-25
Most splitters use N-style connectors. This is because very few splitters are designed specifically for WLAN equipment. Most splitters available today are for use with broadband equipment, much of which uses Nstyle connectors. You can implement N-style splitters with WLAN equipment by making use of jumper cables. These jumper cables are LMR400 cables, not RG58 cables. Three jumpers are used with the splitter. A three-foot jumper connects the access point to the splitter. In addition, two longer jumpers (usually 15 to 20 feet, or 4.5 to 6 m) are used to connect the antennas to the splitter. Cisco Aironet products do not offer splitter kits, but they are available from third parties.
6-24
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
RF Splitters (Cont.) Each antenna connected to the splitter suffers 4-dBi loss Doubles Number of antennas Not the coverage area
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-26
The splitter will add about 4 dBi of loss. If you manufacture your own cables and they are longer than the supplied cables, then the loss will increase (depending on what type of cable you use). Note
The 4-dBi loss is mentioned here as a general guideline for when you are deciding if the use of a splitter will be appropriate. See the technical specifications of the specific splitter for exact measurements.
Each additional antenna that is connected to the splitter experiences a 4-dBi loss. This situation means that while the use of a splitter and a second antenna may allow more coverage area, it will not double the coverage area.
Copyright © 2004, Cisco Systems, Inc.
WLAN Design Considerations
6-25
Amplifiers The FCC rules clearly state the following: Section 15.204(b): External radio frequency power amplifiers shall not be marketed as separate products. Section 15.204(c): Only the antenna with which an intentional radiator (transmitter) is originally authorized may be used with the intentional radiator.
WorldLink Amplifier
These rules mean that unless the amplifier manufacturer submits the amplifier for testing with the Cisco access point and antenna, it is not allowed to be sold in the United States.
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-27
Under FCC rules, amplifiers are typically not permitted unless they are certified as a complete system.
FCC Rules for Intentional Radiators, Section 15.204 The FCC rules for intentional radiators appear in Section 15.204 as follows: External RF power amplifiers and antenna modifications: Except as otherwise described in paragraph (b) of this section, no person shall use, manufacture, sell or lease, offer for sale or lease (including advertising for sale or lease), or import, ship, or distribute for the purpose of selling or leasing, any external radio frequency power amplifier or amplifier kit intended for use with a Part 15 intentional radiator. A transmission system consisting of an intentional radiator, an external radio frequency power amplifier, and an antenna, may be authorized, marketed and used under this part. However, when a transmission system is authorized as a system, it must always be marketed as a complete system and must always be used in the configuration in which it was authorized. An external radio frequency power amplifier shall be marketed only in the system configuration with which the amplifier is authorized and shall not be marketed as a separate product. Only the antenna with which an intentional radiator is authorized may be used with the intentional radiator.
6-26
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
NEMA Enclosures Sometimes access points may be located in areas where they are subject to extreme moisture and temperatures, as well as dust and particles. These access points may need to be mounted inside a sealed enclosure. These enclosures are generally referred to as NEMA enclosures. This topic discusses NEMA enclosures and the challenges that they present.
NEMA Enclosures
Protect equipment in harsh environments National Electronics Manufacturers Association (NEMA) Rating system NEMA 113
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-28
NEMA stands for the National Electrical Manufacturers Association. NEMA has a rating system for enclosures. The ratings are as follows: Type 1: Intended for indoor use primarily to provide a degree of protection against (hand) contact with enclosed equipment. This type of box is usually a low-cost enclosure but suitable for clean and dry environments. Type 2: Intended for indoor use primarily to provide a degree of protection against limited amounts of falling dirt and water. Type 3: Intended for outdoor use primarily to provide a degree of protection against windblown dust, rain, and sleet; undamaged by ice that forms on the enclosure. Type 3R: Intended for outdoor use primarily to provide a degree of protection against falling rain and sleet; undamaged by ice that forms on the enclosure. Type 4: Intended for indoor use primarily to provide a degree of protection against windblown dust and rain, splashing water, and hose-directed water; undamaged by ice that forms on the enclosure. Type 4X: Intended for indoor or outdoor use primarily to provide a degree of protection against corrosion, windblown dust and rain, splashing water, and hose-directed water; undamaged by ice that forms on the enclosure.
Copyright © 2004, Cisco Systems, Inc.
WLAN Design Considerations
6-27
NEMA Enclosures (Cont.)
NEMA Types 2, 4, 4x most commonly used for WLAN equipment Can be purchased through local hardware distributors Do not come equipped for WLAN equipment
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-29
Type 6: Intended for indoor or outdoor use in which occasional temporary submersion is encountered. Type 6P: Intended for indoor or outdoor use in which occasional prolonged submersion is encountered; provides corrosion protection. Type 12: Intended for indoor use to provide a degree of protection against dust, falling dirt, and dripping noncorrosive liquids. Type 13: Intended for indoor use primarily to provide a degree of protection against dust and spraying of water, oil, and noncorrosive coolant. The NEMA enclosures most often used for wireless networking products are Types 2, 4, and 4X. Some specific situations might require Type 12 or 13. You can purchase these types of enclosures at local hardware and electrical supply stores. Unfortunately, when purchased through these types of supply stores, the NEMA enclosure is little more than a sealed box. There are no external antenna connectors, no internal mounting standoffs, and no internal power supply.
6-28
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
NEMA Enclosures (Cont.)
Mounting Plate with Standoffs
Electrical Workbox
Bulkhead Extender
External Antenna Connector
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-30
Almost no NEMA enclosure is available off the shelf with an internal power supply. Mounting for the access point inside the enclosure can be accomplished similarly to mounting an access point without an enclosure. If the Cisco Aironet 1200 Series Access Point will be powered using the power brick, it will need to have power run to the enclosure and an electrical workbox (plug) installed inside the enclosure if no Ethernet power Category 5 cable is available. In order to attach an external antenna (an antenna mounted inside the box is not very effective), a bulkhead extender will need to be installed. This device is a simple connector that connects to the access point inside the enclosure and provides an antenna connector on the outside of the enclosure. If you are using diversity antennas, you will need two bulkhead extenders. The engineer should make sure that any holes that are drilled into the box are sealed. If even one hole is left unsealed, then the integrity of the enclosure has been compromised. Antenna connectors should be mounted to the bottom of the enclosure to provide as much protection from dripping condensation as possible. It is also a good idea to seal the antenna connection with a product like Coax-Seal.
Copyright © 2004, Cisco Systems, Inc.
WLAN Design Considerations
6-29
NEMA Enclosures (Cont.) Prefabricated NEMA enclosures are available with all of the necessary connections. Special NEMA enclosures are available with solar panels or temperature control. Make sure that NEMA enclosures are mounted securely to avoid injury or damaged equipment.
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-31
Prefabricated NEMA enclosures with antenna connectors, standoff brackets, and surge protectors are available from third parties. They are more expensive than a standard NEMA enclosure but provide better protection for the access point and can save the engineer, the customer, or the installer a great deal of time and trouble. Special NEMA enclosures are also available that are temperature-controlled and make use of solar panels to power the equipment. If a NEMA enclosure is used, it must be securely mounted. A NEMA enclosure that measures 2 cubic feet can weigh as much as 30 pounds. If the enclosure is not properly secured, it could fall, injuring someone, damaging equipment, or destroying the connected conduit for the power. Possible exposure of the wiring creates a potential fire hazard.
6-30
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Summary This topic summarizes the key points discussed in this module.
Summary Network cabling that is associated with the WLAN installation Mounting requirements Site survey document Equipment recommendations for equipment to be installed in plenum spaces
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-32
A detailed site survey should address where access points are to be located, how they will be mounted, how they will be connected to the network, and where any cabling or power may need to be installed. The number one rule when designing the cable portion of a WLAN is to avoid fire hazards and to avoid creating a fire hazard. The engineer should design the cable runs properly. If the customers choose to ignore the engineers recommendations, that is their prerogative. This is one reason why accurate documentation is necessary. In the future the engineer may have to prove that the installed cabling is not what was recommended. Without proper documentation, this will be difficult to prove. By keeping these things in mind while conducting the survey, the engineer will be able to design a WLAN that will not only be reliable, but also easy to install. A few extra minutes as the engineer is doing the survey can save the customer hours of work.
Copyright © 2004, Cisco Systems, Inc.
WLAN Design Considerations
6-31
Review Questions Use the practice items here to review what you have learned in this module.
Review Questions Why is it important to have plenum-rated equipment in a plenum space? What should you be aware of when using connectors and splitters? Why is it important to survey the equipment in the same way that it is to be mounted? Why is it important to be aware of firewall locations prior to starting a site survey? What are NEMA enclosures used for?
© 2004 Cisco Systems, Inc. All rights reserved.
6-32
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
CAWSS 4.04-33
Copyright © 2004, Cisco Systems, Inc.
Module 7
Documentation Overview This module discusses the Site Survey Preassessment Form and the site survey report.
Module Objectives Upon completing this module, you will be able to complete the objectives shown in the figure.
Objectives Define the purpose of a Site Survey Preassessment form Identify what should be included in a site survey report
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-2
Module Outline The outline lists the components of this module.
Outline Overview Site Survey Preassessment Form Site Survey Report Summary Review Questions
© 2004 Cisco Systems, Inc. All rights reserved.
7-2
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
CAWSS 4.04-3
Copyright © 2004, Cisco Systems, Inc.
Site Survey Preassessment Form Once the decision has been made to have a site survey done, the customer will need to fill out a Site Survey Preassessment Form. This topic discusses the Site Survey Preassessment Form.
Site Survey Preassessment Assists in assessing the following: Type of survey that is needed How long it will take Equipment that is needed Introduction to the customer facility
General fact-gathering form © 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-4
The Site Survey Preassessment Form will help to determine what type of survey that the engineer will be conducting, how many days it will take, what equipment will be needed, and what questions the engineer will need to ask during a walkabout. A Site Survey Preassessment Form, once it is completed, provides an introduction to the customer facility. As a result, the engineer should make sure that all of the information that is needed is mentioned in the form. The form, shown in the figure here, is a general informationgathering form. Note
A sample Site Survey Preassessment form has been included in the back of the manual. Create a form unique to your company that fits your needs.
Copyright © 2004, Cisco Systems, Inc.
Documentation
7-3
Site Maps
Stock Room: Metal Shelves
Hitches/Trailers
Offices Coverage not required
Office
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-5
Part of the site survey report should include a floor plan, showing coverage areas, as well as the areas that the customer has defined as no coverage areas. This floor plan, or site map, provides the customer, the installer, and a troubleshooter with some indication of what coverage each access point should be providing.
7-4
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Site Survey Report The product that the engineer will be producing is the site survey report. All of the work that is put into surveying would be meaningless without the site survey report. This report is what the customer is truly paying for. This topic discusses the site survey report.
Site Survey Report Customer needs detailed information. All information gathered during the site survey should be included in the report.
© 2004 Cisco Systems, Inc. All rights reserved.
Site Survey Report
CAWSS 4.04-6
The site survey report is what the customer needs to move forward in installing the wireless LAN (WLAN). The customer is depending on the site survey engineer to provide it with all of the information that it needs to be able to gather the materials and make the necessary adjustments to the network. Make sure that the report includes all of the information that has been gathered. Note
A sample site survey report has been included in the back of the manual. Create a unique site survey report that fits your company needs.
Copyright © 2004, Cisco Systems, Inc.
Documentation
7-5
Site Survey Report (Cont.) The report should be as specific as possible. The surveyor might not be the installer. The report is protection for surveyor and customer. The report should be dated.
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-7
The engineer should be as specific as possible in the report. There is always the chance that the engineer will not be doing the actual installation; therefore, the report should be as clear, concise, and easy to understand as possible. The engineer should think of the report as protection for both the engineer and the customer. In the event of a disagreement or problem, a good site survey report can prove that the site survey was completed per customer requirements at the time of the survey. Put the date of the site survey on the report. An installer may be handed a site survey report later in time and be asked to install the equipment. If there is a date on the survey that is a number of months or years past, the installer may need to question the validity of the survey. When deciding what to put into the report, consider what an installer, or a network engineer troubleshooting the system, would want to see in a site survey report.
7-6
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Site Survey Report (Cont.) Be very specific when describing locations. Use objects and facility markers. Do not use objects or markers that may be temporary.
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-8
When describing access point locations, site survey engineers should be as specific as possible. They should use objects in the facility and other identifiers to explain exactly where the access point is to be located. If the access point is to be located in an aisle, the engineer must specify which aisle, and where that area is located in the facility. The engineer should also specify exactly how the access point is to be mounted. If the location is marked, the engineer needs to explain what was used to mark the location. This way the installer knows what to look for and does not have to guess. Even more important than the access point location, the engineer must specify with as much exactitude as possible where the antenna is to be located. On the wall above the doorway is not enough. On the wall above the doorway, two feet left of EXIT sign is a better explanation. The site survey engineer should not use objects that may be temporary as markers. If the object has moved before the installer arrives, the installer may not be able to find the location and may mount the antenna in the wrong location.
Copyright © 2004, Cisco Systems, Inc.
Documentation
7-7
Site Survey Report (Cont.)
Antenna orientation Not all installers are familiar with the equipment. The more directional an antenna, the more important the orientation description.
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-9
The site survey engineer needs to describe how the antenna is to be oriented. If the antenna is omnidirectional, the engineer might mention that it is to be mounted vertically, with the cable at the top. Not all installers will be familiar with the equipment and how it is designed to be mounted. If the antenna is directional, describe the direction in which it should be oriented. A patch antenna might be described as facing north or directed at the nursing station at the end of the hall. The more directional the antenna, the more important is the description.
7-8
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Site Survey Report (Cont.) Describe the facility. Discuss tools that were used and survey methods. Mention settings that were used for survey. Describe and diagram access point coverage. Mark areas that are covered as well as those not needing coverage. Have customer sign and return a copy of the report. © 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-10
The site survey engineer must describe the facility, its construction, its contents, and the square footage. The engineer should discuss the tools that were used to survey and how the survey was performed. Engineers must describe the settings that were used in the survey, including data rates, channels, packet size, and thresholds. They should also detail the coverage for each access point and make sure that this information is included in a diagram. Electronic diagrams can be generated easily and make any report look more professional. For this purpose, the Microsoft Visio product is available with templates that include items such as access points. The engineer should also mark areas where no coverage is needed. Doing so helps to prevent the customer from coming back later and saying that it wanted coverage in an area where it previously claimed that it did not. Without this information, there is no way of proving that the engineer was instructed not to survey the areas for coverage. The customer must sign and return a copy of the report for the records.
Copyright © 2004, Cisco Systems, Inc.
Documentation
7-9
Site Survey Report (Cont.)
Proper access point, antenna, and power mounting Proposed cabling runs System components Future expansion Site survey objective
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-11
The engineer should include sections in the report that discuss proper mounting of the access points and antennas, and detail the specifications for providing power to the access points, as well as explain how the electrical workboxes should be mounted. Engineers should discuss the proposed cabling runs (power and networking), including where and how they will attach to each system. The report should list the system components, the network media type, and the components that are recommended for connecting. The engineer should also list the WLAN components proposed for that installation and discuss the network topology and planned implementation of the WLAN topology. If the customer discusses future expansion or WLAN client upgrades, that should be explained in the report, as well as any problems that the upgrades might generate. The site survey report must also include the objective for the site survey. What are the needs and expectations of the customer?
7-10
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Site Survey Report (Cont.)
Parts list Access points Antennas Accessories and network components
Diagrams Photographs
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-12
The site survey report should also contain a list of the parts that will be needed. This list should include the following: The total number of access points for the installation and a recommendation that a spare be kept on hand in case of emergency The total number and type of antennas that are needed The network components that have been proposed, if possible Some site engineers go as far as to list the amount of network and power cabling that will be needed for the job and to make recommendations on the type of cabling to be used. Include diagrams showing the facility, access point locations, and proposed cable runs. Whenever possible, include photographs; a photograph of the access point location or proposed antenna installation makes it very clear how and where the equipment should be installed.
Copyright © 2004, Cisco Systems, Inc.
Documentation
7-11
Site Survey Report (Cont.) List contacts for all companies involved For each contact, include the following information: Name Company Address Phone and Fax E-mail
© 2004 Cisco Systems, Inc. All rights reserved.
CAWSS 4.04-13
The engineer should list the contacts for each of the companies involved. These companies may include manufacturer, reseller, customer, and service companies. List names, addresses, phone and fax numbers, and e-mail addresses.
7-12
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
Copyright © 2004, Cisco Systems, Inc.
Summary This section summarizes the key points discussed in this module.
Summary Purpose of the Site Survey Preassessment form Items to be included in a site survey report
© 2004 Cisco Systems, Inc. All rights reserved.
Copyright © 2004, Cisco Systems, Inc.
CAWSS 4.04-14
Documentation
7-13
Review Questions Use the practice items here to review what you have learned in this module.
Review Questions
Why is the documentation such an important piece of the site survey? What is the purpose of having a customer fill out a Site Survey Preassessment form? What information from the site survey should be included in the site survey report?
© 2004 Cisco Systems, Inc. All rights reserved.
7-14
Cisco Aironet Wireless Site Survey (CAWSS) v4.0
CAWSS 4.04-15
Copyright © 2004, Cisco Systems, Inc.
Site Engineering Services Site Survey Preassessment Form Filling out a site survey preassessment form helps us prepare for our arrival at your site and helps us ensure that we design a wireless LAN (WLAN) that will meet your needs and requirements. Please fill in the form and fax it to (Company Name) at (123) 456-7891. If you have any questions regarding this form, please contact your (Company Name) representative at (123) 456-7891.
Customer:_______________________________
Contact:___________________________________
Site address:____________________________
Dept:_______________E-mail:________________
_______________________________________
Phone:______________Mobile________________
_______________________________________
Fax:________________Pager:_________________
Total number of sites: __________ (Please fill out one form for each site) Site number: ______ of ______
No. of buildings at site: ___________ 802.11 compliant: Yes
Hours of operation: _____________
Approx. sq. footage: ___________ Redundant WLAN: Yes
Hours during which site survey may be performed: ___________
No No
Terminal type(s): ___________________________
Total no. of users:
Packet size:
___________________________
Minimum
___________
Average
________
___________________________
Maximum
___________
Maximum
________
___________________________
RF Coverage Coverage Complete inside:
Selective inside:
(Please provide diagram of facility indicating desired coverage)
Complete outside:
Selective outside:
(Please provide diagram of facility indicating desired coverage)
Using WEP encryption? Yes
No
Desired linkspeed(s):
Utilize rate shifting?
No
(Please indicate areas where desired likspeed will be needed)
Yes
11 Mb
5.5 Mb
2 Mb
1 Mb
Existing Network Existing network topology:
Ethernet
Token Ring
All sites use same topology?
Yes
No
Application type(s) to be used on WLAN:
Protocol(s):
__________________
Explain:_________________________________
Client/Server
If Emulation, what type? _________________
Other
Emulation
Other
If Other, explain: __________________________
_________________________ Host environment:
___________________________
_________________________
___________________________
_________________________
___________________________
WAN connectivity:
___________________________ ___________________________
LAN connectivity:
10 Mbps
Hubs
Switches
Existing WLAN? Yes
(check all that apply)
Media
(check all that apply)
100 Mbps
Coax
Copper
Routers
Bridges
No
Fiber
If Copper: Cat 5
Cat 7
Gigabit
If yes, explain:_________________________________________
Site Information Ceiling Height:
8-10 ft.
10-20 ft.
Is lift available?
Yes
No
If No, will customer provide lift?
Racking/shelving?
Yes
No
If Yes, please describe construction: ____________________
Clearance above storage level:
< 4 ft.
Any hazardous areas?
No
Yes
20-30 ft.
4-8 ft.
30+ ft. Yes
No
8+ ft.
(Please indicate hazardous areas on diagram)
If Yes, please describe: ____________________________________________________________ _______________________________________________________________________________
Site Information (Cont.) Temperature range inside facility: ________ Temperature range outside facility ____________ Any freezers? Yes
No
(Please indicate freezer area(s) on diagram)
Temperature (check all that apply)
30p+
Special safety requirements: Steel-Toed Boots
15p-30p
0p-15p
Hard Hat
Safety Glasses
Other non-WLAN RF equipment installed at facility? Yes
No