5G and Satellite RF and Optical Integration 1630819565, 9781630819569

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5G and Satellite RF and Optical Integration

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For a complete listing of titles in the Artech House Mobile Communications Library, turn to the back of this book.

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5G and Satellite RF and Optical Integration Geoff Varrall

artechhouse.com

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Library of Congress Cataloging-in-Publication Data A catalog record for this book is available from the U.S. Library of Congress British Library Cataloguing in Publication Data A catalog record for this book is available from the British Library. ISBN-13: 978-1-63081-956-9 Cover design by Publishers’ Design and Production Services, Inc. Cover image courtesy of ALMA Observatory. © 2023 Artech House 685 Canton St. Norwood, MA All rights reserved. Printed and bound in the United States of America. No part of this book may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, or by any information storage and retrieval system, without permission in writing from the publisher. All terms mentioned in this book that are known to be trademarks or service marks have been appropriately capitalized. Artech House cannot attest to the accuracy of this information. Use of a term in this book should not be regarded as affecting the validity of any trademark or service mark. 10 9 8 7 6 5 4 3 2 1

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Contents Preface The Best of Three? References Acknowledgments CHAPTER 1 5G Radio Spectrum Including RF C Band: Link Budgets and Active and Passive Device Efficiency

xiii xiii xx xxiii

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1.1 New Radio: The FR 1 Bands 1.2 FR1 C Band 1.3 The FR2 Bands 1.4 Smart Phone RF Front Ends 1.5 5G Standards Including NTNs 1.6 What Bands and Technologies Are Supported in Present Smart Phones? 1.7 Can I Make a Phone Call On My 5G Satellite Phone? 1.8 Defining the S-RAN and the Role of the G-WON 1.9 Summary Appendix 1A  Resources and References End Notes

1 3 4 8 10 15 16 17 17 18 20

CHAPTER 2 Optical C Band Link Budgets and Active and Passive Device Efficiency

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2.1 The Best Way to Move Bits About? 2.2 Guided Versus Unguided Media 2.3 Impact of Device Efficiency on Guided and Unguided Media 2.4 Optical Modulation and Optical Band Options for Terrestrial Fiber and Free-Space Optical Transmission 2.5 Device Performance 2.5.1  Device Challenges for Wavelength-Division Multiplexing 2.5.2  Device Efficiency Comparisons 2.6 Modulation in Short, Medium, and Long-Haul Terrestrial Fiber 2.7 The Role of the Digital Signal Processor in RF and Optical Terrestrial and Space Networks and Legacy Copper 2.8 The Copper-to-Fiber Transition and the Passive Optical Network 2.9 PONs and the 5G RAN 2.9.1  PON Performance in the 5G RAN

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2.9.2  Single-Mode and Multimode Fiber—Connector Loss and Other Losses 2.9.3  Differentiating Intrinsic and Extrinsic Losses 2.10 Active Optical Networks 2.11 The 5G C-RAN, D-RAN, S-RAN, Fronthaul, Midhaul, Backhaul, Long-Haul Links 2.12 Longhaul to Fronthaul 2.13 Impact of H-ARQ on Fronthaul Latency 2.14 Common Public Radio Interface and Enhanced CPRI Standards 2.14.1  Standards Groups 2.14.2  Fronthaul, Midhaul, and Integrated Access Backhaul (IAB) 2.14.3  Passive Optical, Active Optical, and Point-to-Point Wireless Integration 2.15 Point-to-Point Wireless V Band, E Band, W Band, and D Band 2.16 5G Networks in 2023—Optical and RF Backhaul Options 2.17 E Band Point-to-Point Radios 2.18 Copper Versus Fiber to the Desk and Fiber to the Sofa (5G TV) 2.19 Plastic Optical Fiber (POF) 2.19.1  POF in the Home 2.19.2  POF in Automotive and Medical Markets 2.20 Power over Guided and Unguided Media 2.20.1  Power over Copper and Cable and Fiber 2.20.2  Power over Free Space—RF and Optical Systems 2.21 Subsea Optical C Band 2.22 Power over Subsea Cable 2.23 RF and Optical Band Plan 2.24 Summary End Notes Additional References and Resources

36 38 39 39 41 42 42 42 43 43 43 44 44 45 47 48 49

CHAPTER 3 RF over Fiber

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3.1 Is Analog the Answer? 3.2 Direct and Indirect Digital and Analog Modulation 3.3 The Role of Analog Optical Transport in 5G eMBB, URLLC Repeater Applications, and In-Band-Access Backhaul (IAB) 3.4 The Role of Analog Optical Transport (AOT) in Network Vendor Interoperability Testing(NV-IOT) [8] 3.5 Enabling Technologies for Analog Optical Fiber Transport 3.6 In-Building Distributed Antenna Systems (DAS) 3.6.1  Passive Analog RF over Coax or Optical over Fiber DAS 3.6.2  Active RF and Optical Digital DAS 3.6.3  Hybrid Optical Analog and Digital DAS as an Evolution of Hybrid Coax and Fiber Analog and Digital DAS 3.6.4  LAN over Fiber and 5G in Building Systems 3.7 Long-Distance RF Analog Transport over Analog Fiber 3.8 RF over Fiber for SATCOM

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3.9 RF Overlay and Legacy RF over Glass Systems 3.10 Analog over Analog Versus Digital Analog 3.11 The Digital Dividend 3.12 Two Hundred Years of Telecom 3.13 Summary Appendix 3A  Vendors of Distributed Access Systems End Notes

64 66 66 67 69 70 70

CHAPTER 4 Space RF Link Budgets

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4.1 Intersatellite RF Links (ISLs)—Introduction 4.2 RF Applications in Space—Past, Present, and Future and Their Impact on Link Design 4.3 Space Weather as a Component of an ISL and Space-to-Earthand Earth-to-Space Link Budget 4.4 The Math and Mechanics of ISL (in Standard SI Units) 4.4.1  Signal-to-Noise and Carrier-to-Noise 4.4.2  Free-Space Loss and the Frii’s Free-Space Path Loss Equation 4.4.3  Energy per Bit and Energy per Symbol 4.4.4  Noise as Seen by the Antenna 4.4.5  Reuse of 5G Beamforming AAUs in Space ISL and Other Novel Options 4.5 Power and Antenna Gain in Space-Effective Isotropic Radiated Power (EIRP) 4.6 Filtering in Space 4.7 Phase Noise in Space 4.8 Analog-to-Digital (A/D) and Digital-to-Analog (D/A) Conversion (DAC) in Space 4.9 ISL in Existing Space Deployments 4.9.1 TDRS 4.9.2  European Data Relay Service 4.10 ISLs—Differences Between Constellation ISL and Formation ISL 4.10.1  HawkEye360 and IcEye as Two Examples of FormationFlying RF Added Value 4.10.2  Iridium ISL and Formation Flying 4.11 Link Budgets, Lawyers, and WRC23 4.12 Summary—RF and Optical in Space Appendix 4A Resources End Notes CHAPTER 5 Optical ISLs—Link and Noise Budgets and Other Considerations 5.1 Introduction 5.1.1  Optical and RF Transceivers 5.1.2  Omnidirectional Light, Retroreflectors, and Simple Transceivers in Space 5.1.3  Multidirectional PTP for Collision Avoidance

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71 74 75 77 77 78 79 79 80 83 84 85 85 86 86 87 89 89 90 90 92 93 96

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5.1.4  Reuse of Terrestrial Optical Components in Space and HAPS 102 5.1.5  Coherent Detection Versus Direct Detection 102 5.1.6  Goodput and Channel-Coding Overheads in an OISL 103 5.1.7  Optical Beamwidth and Pointing Loss 103 5.1.8  RF Thermal Noise and Optical Quantum Noise as a Link Budget Limitation 103 5.2 Homodyne, Heterodyne, and Intradyne Receivers 104 5.3 Optical Conformance Testing—Noise Budgets, Signal to Noise, and Optical Signal-to-Noise Ratio 106 5.4 Optical Heterodyne Noise and Gain Budgets 106 5.5 Pointing Loss and Vibration Loss 108 5.6 Vibration Loss, Jitter Loss, Pointing Loss, and Tracking Loss Noise Budgets 109 5.7 Iridium as an Example of How a LEO Satellite Moves Around in Space, What That Does to the (RF) Link Budget, and What This Means for OISL 110 5.8 Doppler Wavelength Shift and WDM OISL 112 5.9 Other Sources of Noise and Distortion and Unwanted Signal Energy 113 5.9.1 Microphony 113 5.9.2  Unwanted Signal Energy and the PAT Subsystem 113 5.9.3  Unwanted Light Energy in the Beacon Signal and Data Path 114 5.9.4  Mirror Resonance and Mirror Optical Quality 115 5.9.5  RX TX Light Path Mixing and Isolation 115 5.10 Diffraction Limits and the Strehl Ratio as a Measure of Optical System Quality 115 5.11 Laser Beam Quality and M-Squared (M 2) Measurement 116 5.12 Circular and Elliptical Beams Laser Choice and Its Impact on Flux Density with VCSEL as an Example 118 5.13 LNAs and PAs in OISL 119 5.14 Filtering 121 5.15 Filtering Out Solar Noise 122 5.16 Digital Filtering 123 5.17 Phased-Array Optics 123 5.18 5G OISL and the OISL Vendor Supply Chain 123 5.19 Summary 125 End Notes 125 CHAPTER 6 Deep Space and Near Space

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6.1 Heading for the Oort Clouds 127 6.2 5G Spectrum and Standards Summary 129 6.2.1  The Radio Astronomy Bands 129 6.2.2  Deep Space and Near Space ITU Definition 129 6.2.3  Red Shift and Blue Shift 130 6.2.4  Space Distance 130 6.2.5  Narrow Spectral Lines 130

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6.2.6  Radio Frequencies and Bandwidths in Radio Astronomy 6.2.7  Radio Astronomy History and Present Systems—The HalfMinute Summary 6.2.8  Radio Astronomy and 5G Coexistence 6.2.9  Why Bother About Deep Space? 6.3 Deep Space from the Ground (RF) 6.3.1  The Radio Story—Radar 6.3.2  The Radio Story—The Atacama Large and Submeter Array (ALMA) as an Example of RF and Optical Integration 6.3.3  The Radio Story–Square-Kilometer Array 6.4 Deep Space from the Ground (Optical) 6.4.1  Galileo and Monsieur Cassegrain—The Optical Story 6.4.2  Optical Measurements and Precision Cosmology 6.4.3  Optical Telescopes for Astronomy and Optical Ground Station Integration 6.4.4  Mount Paloma 6.4.5  The Large Binocular Telescope—Mount Graham International Observatory 6.5 Deep Space from Deep Space—The JWST 6.5.1  JWST Arrives at L2 6.5.2  K-Band Space-to-Earth Radio Links from JWST 6.5.3  JWST and the Deep-Space Network 6.5.4  Physical Stability on Earth and in Space 6.6 Deep-Space and Near-Space Network Integration 6.6.1  The Deep-Space Difference 6.6.2  Seventy-Meter DSN Antennas 6.6.3  The 34-m Subnetwork 6.7 Deep Space from the Moon and CISLunar Space 6.8 X-Rays from Deep Space 6.9 The Near-Space Network 6.9.1  What Is the Near-Space Network? 6.10 The A–Z of the NSN 6.11 Near Space from a Cold Place 6.12 Near-Space Optical Network 6.13 Deep-Space Data Rates, Latency, and CCSDS Standards 6.14 Space Optical and Radio Standards 6.15 Deep-Space Science 6.16 Summary Appendix 6A Resources End Notes

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130 131 132 132 133 133 134 136 137 137 138 139 140 141 141 141 143 143 144 145 145 145 146 147 148 148 149 150 154 154 155 155 157 157 158 158

CHAPTER 7 Ground Station and Earth Station Hardware and Software—Challenges of Supporting LEO, MEO, and GSO Systems

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7.1 The Story So Far 7.2 The Hyper-Linked Hyperdata Center

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7.3 Hyperdata Centers and Points of Presence 162 7.4 Gateways, Ground Stations, Earth Stations, and Teleports 163 7.5 Mr. Brunel, Big Ships, Landing Stations, and Long-Distance Subsea Cables 165 7.6 Subsea to Terrestrial Connectivity—Scale Issues and Politics, with Africa as an Example 167 7.7 Fiji to Tonga—The Cost of Cable Failure 168 7.8 Subsea Cable Economics—Optical C Band Under the Sea 168 7.9 From Station Clocks to Space Clocks 169 7.10 Timing and Earth Station Scheduling 169 7.11 Time and Positioning Accuracy 169 7.12 5G at Sea 171 7.12.1  Ultra-Large Container Ships 171 7.12.2  Safety at Sea and Automatic Identification Systems 171 7.12.3  Container Ships, Cruise Ships, and Earth Stations 172 7.12.4  5G at Sea and Maritime Port Integration 173 7.12.5  Sea IOT 173 7.12.6  Optical ESIM—C Band at Sea 173 7.13 Longwave to Light—Marconi and Musk 174 7.14 The Optical Outback 175 7.15 Quantum Earth Stations 178 7.16 Optical Computing and Optical Storage 180 7.17 Ground Versus Space Complexity 181 7.18 Summary 182 Appendix 7A  Resources—Timing and Synchronization 183 End Notes 183 CHAPTER 8 Low-Altitude Platforms

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8.1 Whatever-the-Weather Wireless 187 8.2 Regulation and ATC 189 8.3 Regulation of Drones 190 8.4 Drone Airframe Options, Size, and Wi-Fi Data Rates 191 8.5 Flying Cars and 5G Urban Air Mobility 192 8.6 War Drones for War Zones 193 8.7 Height, Altitude, Radio Altimeters, C-Band Protection Ratios, and In-Flight Connectivity 195 8.8 Precision Flying Using MEO GPS and LEO Time and Freqency References 197 8.9 Opportunistic Navigation 199 8.10 Summary—Beyond-Line-of-Site (BLOS) Navigation, Communications, and Control 200 8.11 Large and Lost at Sea Malaysian Airlines MH 370 200 8.12 Aviation Radio Spectrum 201 8.12.1  Band Fundamentals 201 8.12.2  Model-Aircraft Radio Control 202

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8.12.3  The Aviation Bands 203 8.12.4  First-Person-View Drone Frequencies in the ISM Bands 205 8.13 WRC 23 206 8.14 Longwave, Medium-Wave, Shortwave, and VHF Radio Systems at WRC-23 206 8.15 In-Flight Connectivity 207 8.16 5G ATG IFC 208 8.17 SIMS, Multi-SIMS, and ESIMS and the 5G ATG Link Budget 210 8.18 Connecting from Above Using Optimized Single-Band Radiosas an Alternative to 5G ATG 211 8.19 Optical Versus RF from 0 to 100 km—Shannon and RF and Optical Link Budgets 214 8.19.1  High-Power High-Tower Cellular Repurposed for 5G ATG 214 8.19.2  Market Scale and the Shannon Limit 214 8.19.3  Aircraft Size and the Shannon Limit 215 8.19.4  The 33-Layer Atmospheric Model 215 8.19.5  Optical Scattering and Adaptive Optics—Greenwood, Mie, and Fraunhofer 215 8.20 Optical Control of Drones and UAVs 216 8.21 Plane Spotting from Space 216 8.22 Summary 217 End Notes 217 CHAPTER 9 High-Altitude Platforms

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9.1 5G HAPS—The Basics 9.2 HAPS Alliance, the GSMA, and ITU HAPS Spectrum Allocations 9.2.1  L-Band and S-Band HAPS Mobile Spectrum 9.2.2  Other HAPS Mobile Spectrum in Low Band (UHF) and Mid Band (L Band and S Band) 9.2.3  HAPS Fixed Service Spectrum 9.2.4  V Band, W Band, and E Band for HAPS 9.3 Platforms and Power 9.4 Hydrogen Versus Helium for HAPS 9.5 RF Versus Optical End Notes

219 224 224 225 225 226 227 228 229 229

CHAPTER 10 RF and Optical Technology Enablers

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10.1 The Five Gs—RF Technology Time Scales 10.2 The Ten Gs—Optical Technology Time Scales 10.3 Electronics Versus Photonics 10.4 From 2D to 5D—Optical Computers and Photonic Storage 10.5 Summary—Light at the End of a Tunnel End Notes

231 233 234 235 236 236

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CHAPTER 11 Technology Economics of RF and Fiber for Terrestrial and Space Networks

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11.1 Link Budget Economics 11.2 Moore’s Law and Our Law—the Law of the Dollar and the Decibel and the Impact of the Link Budget on RF and Optical Network Economics 11.3 Space Value Versus Terrestrial Value 11.4 Space Costs 11.5 Space Spectrum 11.6 Space Standards 11.7 6G and Satellite RF and Optical Spectrum Standards and Scale End Notes

239

About the Author

245

239 241 241 242 242 242 243

Index 247

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Preface The Best of Three? This is the third of three books about 5G and satellite technology written for Artech House. The first book, 5G Spectrum and Standards, published in 2016, was written just after the 2015 World Radio Conference and just before Release 15 of the 3GPP radio standard, which marked the shift in focus from LTE advanced (4G) to the fifth-generation (5G) mobile broadband physical layer. The second book 5G and Satellite Spectrum, Standards, and Scale, published in 2018 (a year prior to the 2019 World Radio Conference), coincided with Release 16 of the 3GPP standard, which offered additional capabilities, such as narrowband Internet of Things (IOT) and enhanced positioning capabilities. This book made the general point that space costs were reducing over time, while 5G terrestrial costs were increasing in line with network density. In particular, real estate costs, the expense of digging a trench for fiber, and the price of electricity were remaining constant or increasing but not decreasing. On the other hand, the cost of getting to space was halving every 18 months, and the operational life of satellites was becoming longer than expected and getting longer over time. The expected operational life of the first generation of Iridium satellites was seven years. Some satellites were replaced, but the constellation remained operational until a major upgrade 20 years later. The absence of real estate costs in space, along with free electricity, underlined the logic of considering space telecommunication to be a fast growth sector. This third book, 5G and Satellite RF and Optical Integration (published in November 2022), was written while preparations were ongoing for the 2023 World Radio Conference and coincided with Release 17 of the 3GPP standard and the finalization of the work items for Release 18, including what is now known as 5G Advanced. The Release 17 standard advanced earlier study and work items on the integration of new radio (NR) with nonterrestrial networks (NTNs), defined as low-Earthorbit (LEO), medium-Earth-orbit (MEO), and geostationary (GSO) satellites and high-altitude platforms (HAPS). A parallel workstream addressed nonterrestrial Internet of Things (IoT) connectivity. In addition, NR introduced a new set of band numbers divided into frequency range 1 (FR1) from 410 MHz to 7.125 GHz and frequency range 2 (FR2) from 24.25 to 52.6 GHz, subsequently extended to 71 GHz. It is useful but not essential to read the two earlier books, both of which are still available from Artech House, but this book can be read on its own; when relevant, xiii

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it references earlier work using appendixes to indicate the location of tables and figures by page number. However, the following high-level summary sets the scene for this book: 5G Spectrum and Standards analyzes the radio spectrum/band and technical specifications under consideration for 5G at that point in time, along with the related performance, cost, and vertical market expectations. In addition, the book studies the cost of coexistence between 5G operators and other user communities cosharing spectrum, including radar (from the C band upward); radio astronomers (anywhere from the VHF to V band); GSO, MEO, and LEO satellites in the Ku, K, and Ka bands and above; and satellite TV (C band, Ku band, and K band). For each band, we examine channel bandwidth options from narrowband to wideband and the impact of wideband channels on out-of-band (OOB) and adjacent channel performance [adjacent channel leakage ratios (ACLRs)], an important part of the coexistence cost equation. This includes a review of the millimeter band for 5G and the challenges and opportunities of coexisting with automotive radar and fixed point-to-point systems finishing with a cursory look at terahertz radio and optical free-space systems at infrared through to ultraviolet. The book also lists the existing radio bands, including the defense-related spectrum and their various nomenclatures. The second book, 5G and Satellite Spectrum, Standards, and Scale, benefited from public domain visibility to the band plans and interference mitigation strategies proposed by the new LEO market entrants, courtesy of the FCC filings process [1]. The starting point was an address to the nation made by President Ronald Reagan on March 23, 1983. The speech—which came to be known as his “Star Wars speech,” as it coincided with Return of the Jedi, the third of the Star Wars films—set out the rationale for an increase in spending on space-based missile interception predicated on the perceived threat from Russia, the “axis of evil” as represented by the U.S. political and popular press. Forty years later and post-911, two Gulf Wars, and the Afghanistan conflict, it is debatable whether this shift in policy made the world a safer place, but, nevertheless, the shift in spending has had a positive impact on the technology economics of space communication. Pointing acquisition-and-tracking (PAT) systems for intersatellite and interconstellation optical links are one small but significant example of a spin-off benefit from research on space defense. There are plenty of new things to talk about in this book. GSO operators are moving to very high–throughput satellites (VHTSs) and establishing commercial links with MEO operators (e.g., SES and 03B) [2]. Existing LEO operators in the L and S bands are consolidating their service offers from their refreshed constellations, including enhanced voice and data, location, and positioning [3] and, more recently, global drone telemetry and telecommand [4]. Proposals are now submitted to the FCC for LEO, MEO, and GSO constellations integrated with high-altitude platform stations (HAPS), aircraft, and other airborne platforms. CubeSATS have moved from academic research and trials to commercial deployment. Companies such as Myriota [5] are collecting data from remote IOT terminals in the Australian outback with a 30-mW uplink in the VHF band (160.975–161.475 MHz) and UHF band (399.9–400.05 MHz and 400.15–401 MHz). Radio in space is on a roll, and a wide choice of technologies, not all of which are cellular, have a role to play, but 5G tends to be in the mix somewhere. The data from the Myriota network is delivered to farmers and fishermen on their

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smart phones, so although the book is 5G-focused, we include other technologies to understand how added value is realized through technical and commercial integration. This includes radio technologies such as Wi-Fi and Bluetooth and optical enabling devices such as coherent DSP. Spectrum experts and lobbyists preparing for the 2019 World Radio Conference were relaxed about new technologies in the VHF band but less relaxed about what would happen to the V band and the spectrum in between, including the C Band and the K bands. The 5G vendor supply chain, and to a lesser extent the 5G operator community, were keen to stake their claim on “the millimeter band.” Technically this was anything above 30 GHz, but in practice the race was on to secure rights for bandwidth from the C band to the K bands and beyond. The battle lines between the 5G and satellite community were drawn but a fullscale fight was avoided once the satellite industry realized it could raise money from the disposal of C band assets, which could be spent in a multitude of other ways. For example, Eutelsat’s $550 million–dollar investment in OneWeb in late 2021 was financed from the proceeds of the auction of C band spectrum. Despite a number of companies working together on multiconstellation service offers (e.g., the SES/O3B GSO/MEO), there were underlying tensions between incumbent operators and new LEO market entrants. The new LEO entities were required to demonstrate that they were not going to cause interference to existing MEO and GEO satellites using the same Ku, K, and Ka bandwidth. This has proved hard, and some of the solutions, such as turning off RF transmission from a LEO as it passes over the equator to minimize LEO-to-GSO interference and implementing angular power separation incur performance loss. Angular power separation increases path length. This increases link loss and latency. This is important because much of the added value of the new LEO business model is predicated on using the K band’s power efficiently both for Earth-to-space and space-to-Earth links and for intersatellite and interconstellation cross-connect. The rest of the book covers RF link budgets and latency including satellite channel models, launch technology innovation, satellite technology innovation, antenna innovation, multiorbit constellations, production and manufacturing innovation, commercial innovation, standards, business models, and emerging opportunities for cooperation between the 5G and satellite industry, including in-band backhaul. At the time of writing, the auctioning of C band spectrum is ongoing and producing rather good results for all involved parties. Over the past 30 years, the terrestrial TV industry and cellular community have been involved in an initially fraught process of moving TV channels from the 800-MHz and 700-MHz bands into the 600-MHz band. This was made technically and commercially possible by the adoption of more efficient video coding (enhanced DVB standards), single-frequency networks (SFNs) rather than multifrequency networks (MFNs), and by the growth of other delivery options, including satellite TV at 12 GHz (the Ku band) and better Internet connectivity. This came to be known as the digital dividend. The C band is a similar story. 5G operators and their shareholders and investors have bought into the notion of spending billions of dollars on parts of the band. The satellite TV industry has been handsomely rewarded for compressing the TV bands into the upper part of the C band. As in the case of terrestrial TV, this has been made possible by more efficient video coding and a transition to

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other delivery channels including Ku band (12-GHz) and K band (18-GHz for super high-definition TV). A similar positive narrative is emerging for 5G investments in the millimeter bands, both from the operator community and its supply chain, which will benefit from the additional network density needed to implement FR2 radio networks. This might seem problematic for the satellite industry given its present dependence on the K bands, but several things have changed. A number of entities are now moving toward implementing the direct delivery of broadband services to smart phones from low-Earth-orbit satellites (LEO). These are planned to be implemented at S band, L Band, or at UHF (700, 800, or 900 MHz). The additional spreading loss implies a need for something in the range of 30 dB of additional gain over a terrestrial link. Two relatively new companies, Lynk Mobile [6] and AST Space Mobile [7], intend to achieve this by deploying large antennas into space. At the time of writing, AST are developing a 64-square meter phase array designed to unfold in space with the goal of providing sufficient uplink and downlink gain to support a range of broadband direct connectivity services. Narrowband connectivity direct to handheld devices is already technically and commercially proven in existing LEO constellations (Iridium in L band and Globalstar in S band and potentially C band), though not at a consumer scale. Even the ability to deliver text messaging in areas with terrestrial coverage has potentially high added value, particularly if it is achievable with minimal or no changes to existing smart phones (as claimed by AST and Lynk). Indeed, the business model is dependent on this criteria, as most of the added value will be realized from legacy user devices with legacy front ends and legacy multiband chip sets. Some legacy phones may have high antenna losses when receiving signals from high elevation, possibly resulting in some phones working better than others, which could be problematic for the operator community. Ephemeris data from a constellation could potentially be downloaded to a legacy smart phone on an app to determine cell-handover candidates, but it is hard to see how Doppler tracking could be done without changes to the baseband chip set. The 3GPP relay specifications may be one way around the cell registration and handover issues [8]. Longer-established operators (e.g., Inmarsat) have also announced plans to develop and deliver an integrated GSO, LEO, and terrestrial 5G networks, with LEO test satellites now launched and active [9]. Going forward, the wider industry assumption is that Release 17 and subsequent releases addressing voice and wider band data services from a LEO satellite direct to a smart phone will require physical layer and MAC layer changes and RF front end and baseband hardware optimization. These are detailed later in the preface and in Chapter 10. Closing the RF link budget for a higher data rate implies putting a significant amount of RF power and receive sensitivity into space, which may or may not be cost-economic. Longer path lengths introduce delay and delay variability, which potentially require changes to higher-layer IP protocols. We revisit this topic in Chapter 4. Standards work has moved toward making a consumer cost model possible, although at the time of writing, no major handset vendor has announced availability of a handset that will seamlessly and efficiently roam to a low-orbit-satellite– enhanced Node B (the 3GPP description of a 4G or 5G base station), and none of the major network vendors, including Huawei, Ericsson, or Nokia, have shown

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enthusiasm for delivering narrowband or broadband 4G or 5G from space. To date, only ­Huawei has made any public announcement of development work in progress, and that work is only in the context of 6G and terahertz test platforms rather than 5G and satellite [10]. There are, however, other ways to make money from space including direct connectivity to user terminals functioning as Wi-Fi hot spots. This is a continuation of the ongoing story of satellites as a mechanism for connecting the unconnected and under-connected. SpaceX has made early headway into this market on the back of broadband rural connectivity subsidies. The cost and complexity of subscriber equipment has been an issue due to the need to combine mechanical pointing and steerable antennas. Long path lengths at low elevation are also problematic due to path loss, a combination of propagation loss through the atmosphere at Ku band and building blocking, and a loss of efficiency from flat-panel antennas receiving signals from low elevations. These problems disappear or at least become less problematic as more satellites are brought on-stream, and the constellation moves to having a satellite nearly overhead nearly all the time. This underlines the firstmover advantage that SpaceX has over its competitors. Another way to make money from space is to capture value from the rapid increase in imaging bandwidth. This comes from multiple sources, including radio and optical telescopes looking out into deep space and back to the beginnings of the universe [11] and radio and optical telescopes looking back to Earth either measuring RF emissions, a valuable capability for defense and security agencies, or from systems capable of capturing images at submeter resolution either from synthetic aperture radar typically at X band or from infrared and optical imaging. Together these imaging systems are capable of generating an almost infinite amount of bandwidth. The value of the bandwidth is a function of how much it costs to capture and get back to Earth and how much the data is worth to defense, security, and commercial customers. Apparently mundane applications such as counting cars in car parks have commercial value. Environmental value is realized from detecting and measuring deforestation, counting penguins and polar bears, measuring ice caps and carbon emission, and detecting, measuring, and tracking maritime pollution. The data sets are of particular value when correlated together, an area where artificial intelligence is proving useful. This data can be returned to Earth at more or less any radio frequency. We still talk to spacecraft heading toward the Oort Clouds via Earth-based VHF radio telescopes, and most of the LEO downlinks are at Ku, K, or Ka band, with V band now being planned. However, it is hard to avoid the conclusion that our ability to realize value from space imaging is going to be limited by a lack of radio downlink bandwidth, particularly as radio interference levels are already high and becoming more of an issue over time. This brings us to the other topic addressed in this book, the role of free-space optical technology in 5G and satellite networks. Optical free-space links from ground to aircraft were first demonstrated in 1981 by MacDonnell Douglas; this was followed by the introduction of optical links from the air to submarines in 1991, from ground to deep space in 1992, optical space relays in 1996, and GSO to ground in 1995. A LEO-to-GEO link was demonstrated by the European Space Agency (ESA) in 2001. Subsequently,

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xviiiPreface

ESA introduced air-to-GSO in 2006; TESAT introduced LEO-to-LEO and LEOto-ground in 2008; and ESA introduced LEO-to-GSO in 2013, moon-to-Earth in 2013, and GEO-to-Earth back to GEO in 2020 [12]. The free-space optical supply chain reuses components from terrestrial fiber to build optical transceivers that can span links of tens of thousands of kilometers between geostationary satellites using just a few watts of power and supporting tens of gigabits of throughput. Aiming subsystems developed by defense agencies have enabled the development of PAT systems that can establish and maintain inter-LEO links. Adaptive optical-correction systems developed to improve the performance of ground-based optical telescopes are being repurposed to optimize ground-to-space and space-to-Earth optical links. SpaceX has always stated its intention to implement optical cross-connect, but PAT systems are sensitive to vibration and pointing and tracking accuracy needs to be done at a resolution of microradians. (A microradian is 0.00006 of a degree.) The latest satellites in Starlink’s polar shell are equipped for the first time with optical transceivers. Pointing, acquisition, and tracking becomes easier when LEOs are closer together, so increasing the satellite count in space increases optical crossconnect efficiency (acquisition time and point-and-track accuracy and the optical power budget). Optical cross-connect also improves service for maritime users by reducing the need for multiple relays via ground-station systems [13]. Generally speaking, increasing complexity in space reduces complexity on the ground. Bear in mind that SpaceX plans to have 42,000 satellites in space launched from the next generation super-heavy launch vehicle. If these are all optically cross-connected and have optical space-to-ground and ground-to-space connectivity, then Elon Musk will have achieved another world first, a global free-space wide area optical network (G-WON) that will be faster than subsea fiber over distances of a few thousand kilometers. The caveat is that rain and fog and snow and heavy cloud cover and scintillation (caused by close-to-the-ground heating effects) can introduce hundreds of decibels of fading loss into ground-to-space and space-to ground optical links, but it illustrates the story that we are trying to tell in this book: Free-space optical is a useful and arguably crucial part of next-generation wireless networks and thus needs to be integrated into present and future network planning and future standards. Furthermore, there are always cloud-free routes to Earth; they just need to be detected and used. An additional caveat is the uncertainty of how fast the space industry can and will reduce the cost of delivery to space. To put this into context, 30 years ago, it cost $100,000 to send a kilogram of payload into space. At the end of 2021, SpaceX was charging the U.S. Department of Defense (DOD) $150 million per launch to deliver 70 metric tons to LEO, less than $150 dollars per kilogram. In a tweet on May 7, 2020, Musk stated that his aim was to reduce costs to $150,000 per launch for a 150-ton payload. That might take a while and is a cost rather than price estimate, but it would represent a reduction of four orders of magnitude, mostly achieved over the past 12 years. A shift to methane, the fuel used in next-generation SpaceX rockets (along with liquid oxygen) has the promise of a major reduction in fueling cost and can even be argued to be environmentally friendly. This implies that Musk has the capability to put a 5G network into space, but his commercial success

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The Best of Three?  

xix

to date has been based on doing things differently and being in control of a large part of the supply chain. In the context of Starlink, this implies connectivity with Starlink terminals rather than 5G smart phones or 5G IOT devices. To address a consumer market cost means that the present terminal cost, which at conservative estimates must be well over $2,000, would need to reduce to $200 (about half the cost price of a high-end smart phone) or $20 dollars for low-income markets. The alternative involves cross-subsidizing terminals from service fees, a well-tried-andtrusted business option in the cellular industry, but it puts price points well out of reach of most people in most developing countries. The key to achieving this apart from the subsidy and manufacturing scale is to have lots of satellites (nearly always nearly overhead) so that simple transceivers with a dish antenna pointing straight up into space will work adequately well. At the lower-orbit heights now being planned for the Starlink constellation, this will be achieved with 20,000 satellites, so 42,000 should be more than enough. One can assume that every Tesla car will have a Starlink transceiver as well, and there will be plenty of those about. Musk is happy to point out the potential risks in all of his many masterplans, but he does have a habit of delivering even if it takes longer than expected. However, there has been an increase in common interest between the 5G and satellite development community from an earlier position in which the two industries were not technically or commercially well-aligned. Put simply, both industries need each other. The 5G industry has spent hundreds of billions of dollars on radio spectrum over the past 20 years and similar amounts on infrastructure investment. Global competition policy, influenced by a need to maximize auction incomes, has resulted in many counties having five operators, only one or two of which are scaleeconomic. Saved by the smart phone, this level of investment has been sustainable but stressful and has introduced subtle but significant technical and commercial inefficiency. At a technical level, as we discuss later in Chapter 1, an increasing number of bands supported within small-form factor devices has made it hard to maintain receiver sensitivity. The rule here has been and continues to be that every decibel taken off the link budget due to filter insertion loss, unwanted front-end mixing, or inefficient poorly matched antennas requires a terrestrial network density increase of 10%. Base station sites now have hundreds of watts of power and sometimes several kilowatts of power aggregated across multiple channels in multiple bands. This means that base station receiver sensitivity can be hard to maintain, which means that there are losses at both ends of the transmission path. Unsurprisingly, the result is that coverage can be patchy, even in urban areas. Adding seamless satellite connectivity to a smart phone seems like a smart idea, but a smart phone is already full of other stuff, and ideally, particularly for voice and wider band data services, the antenna needs to point directly upward rather than toward a base station at a 30-degree elevation. Qualcomm, an early investor in Globalstar, announced support for the N53 TDD band at 2.4 GHz in its X65 modem, which could at least be used by Globalstar in the United States, although not in some other markets [14]. Baseband vendors such as Mediatek with a presence in the 5G chip set market [15] and GNSS market are well-positioned to deliver NTN-optimized chip sets and are active in the 3GPP NTN standards process. Sierra Wireless [16] has similar expertise spanning the GNSS and 5G markets and an ability

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xxPreface

to translate application knowledge from MEO GNSS to LEO device development including the management and processing of ephemeris data. It is however a classic chicken-and-egg situation. There is no point in adding seamless 5G satellite connectivity into a smart phone until e-Node Bs are installed in space. There is no point in putting eNodeBs into space unless there is a range of IOT devices and satellite-enabled 5G smart phones that can support, at a minimum, an adequate subset of 5G services. There is no point in producing a baseband chip set for a 5G satellite smart phone until RF front ends have the capability of accessing satellites’ power efficiently, which probably includes in-band 5G and adjacent-band satellite frequency allocations. Adding NTN capability will also increase conformance test time and conformance cost. However, we eat eggs for breakfast and chicken for dinner—and even maybe the occasional chicken omelet—so somehow everything is possible, and the rest of this book tries to set out how the apparently impossible can become possible over time. Similarly, there are at present no 5G baseband or RF chip set vendors with a major presence in optical processing, although this may change in the future. For the moment let us stay in the world of radio rather than optical engineering. In Chapter 1 we review the NR 5G bands and see which ones are best-suited to in-band satellite connectivity. Satellite bands that are immediately adjacent to 5G NR bands are also potential candidates, though they require a larger passband and may require changes to RF front-end architecture. We also look at the NTN study and work items in 3GPP Releases 17 and 18 in Chapter 1. Chapter 2 compares the RF C band and optical C band and highlights the commonalties and differences between RF and optical transceivers and the similarities and differences between fiber and free-space optics. Chapter 3 covers RF-over-fiber, including link budgets and future trends. Chapter 4 studies RF in space and crossconnect link budgets, and Chapter 5 does the same for optical cross-connect. Chapter 6 covers the techniques used in deep-space radio and deep-space optical links and the translation of these technologies to near-Earth and terrestrial networks; Chapter 7 focuses on ground and Earth station hardware including the impact of multiorbit constellations and emerging RF and optical integration trends. Chapter 8 covers low-altitude platforms, drone telemetry and telecontrol, and stabilization and dead reckoning using integrated RF and optical techniques. Chapter 9 does the same for HAPS. Chapter 10 reviews fiber and optical technology enablers, and Chapter 11 takes the topics covered in Chapters 1–10 and places them in an economic context. Whether this is the best of the three books written for Artech is for you to decide, but it is certainly the most up-to-date, and its publication coincides with an inflection point where terrestrial and nonterrestrial and RF and optical networks are starting to be integrated in a financially useful way.

References [1] https://fcc.report/IBFS/Filing-List/SAT. [2] www.ses.com/press-release/ses-government-solutions-provides-medium-earth-orbit -satellite-services-combatant. [3] https://satelles.com/gps-world-article-discusses-benefits-of-iridium-satelles-stl-service/.

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xxi

[4] https://www.iridium.com/markets/uav/. [5] https://myriota.com. [6] https://lynk.world. [7] https://ast-science.com/. [8] https://global5g.org/sites/default/files/3GPP_RAN_Apr2020.pdf. [9] Inmarsat Orchestra hits first milestone in space with new LEO satellite—Inmarsat. [10] https://www.globaltimes.cn/page/202104/1221959.shtml. [11] The launch of the James Webb Telescope, Christmas 2021. [12] https://www.facultas.at/item/Inter-Satellite_Optical_Wireless_Communi/Avireni_ Bhargav/Jitendra_Kumar_Saini. [13] https: //smartmaritimenetwork.com/2021/01/27/musk-confirms-laser-crosslinks-for -starlink-satellite-network/. [14] https//investors.globalstar.com/news-releases/news-release-details/globalstars-band-n53 -qualcomms-x65-modem. [15] https//i.mediatek.com/mediatek-5g. [16] www.gpsworld.com/5g-module-with-gnss-released-by-sierra-wireless/.

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Acknowledgments I would like to thank the following people in particular for their help and technical guidance: William Mueller of Broadcom for his help with FBAR filters and RF subsystem design in Chapter 1, Andy Sutton of BT EE for his insights into 5G optical fronthaul and backhaul in Chapter 2, and Richard Jacklin of Vialite for guiding me through the mysteries of RF over fiber in Chapter 3. That said, any possible errors and omissions in those chapters would be my fault, not theirs. I would also like to thank my friend and colleague Daniel Tan of Niche Markets in Singapore for his tireless research on technical and commercial innovation across Asian, U.S., and European markets. Although this text is primarily intended as an engineering book, it is always useful to temper engineering enthusiasm with a dose of economic reality, and my colleague John Tysoe, as always, has provided reliable advice on business ventures that apparently defy the rules of basic physics. As we say in Chapter 11, if the link budget doesn’t close, the business will. Thanks in addition to the team at Artech House and in particular to Merlin Fox for having the courage to commission yet another book from me and to Casey Gerard and the production team for hustling the project through at high speed. It is also customary to thanks one’s family for their forbearance, but our children now have their own lives, and my wife seems to have realized that writing a book every five years is just something that happens. Apart from the grass growing and the roses not being pruned, there are no huge domestic downsides—to date at least.

xxiii

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CHAPTER 1

5G Radio Spectrum Including RF C Band: Link Budgets and Active and Passive Device Efficiency

1.1

New Radio: The FR 1 Bands The design challenge for 3G, 4G, and 5G RF front-end designers over the past 25 years has been defined by the need to support an increasing numbers of bands and technologies and, more recently, operator-, country-, and region-specific multiband aggregation options. This has required new approaches to front-end design including multiple hexaplexer switch paths. The difficulty has been producing RF front ends that perform well across all supported bands. While it is possible to optimize RF performance across two or three core bands, there is generally an associated cost in terms of performance in other bands, which means that the user experience can be variable both in terms of throughput and range. While this may not be immediately noticeable to a user, there will be an operator coverage and capacity cost that will have an indirect but measurable impact on how long it takes to make a return on the purchase of spectrum at auction and network investment. As referenced in the preface (and Chapter 11), the rule of thumb that a decibel loss of RF performance is equivalent to a 10-percent increase in terrestrial network density still applies. This relationship between device performance and network opex and capex cost is a determining factor in 5G delivery economics. It also means that if in-band satellite connectivity is to be added as a standard option to a smart phone, it has to be done without a loss of terrestrial performance; furthermore, it should fit within existing form factors and work consistently when the device is held in the hand. It should not add weight, and preferably, it should not incur additional cost. 5G spectrum is closely coupled to the 3GPP Standards process. The relevant work group is RAN4, with 5G NR defined from Release 15 onward in two frequency ranges (FRs). FR 1 was originally specified from 450 to 6,000 MHz with bands numbered from 1 to 255 commonly referred to as sub-6 GHz but now extended (in Release 17) to 7.125 GHz. FR 2 was specified from 24.25 to 52.6 GHz with bands numbered from 257 to 511 and subsequently extended in Release 17 to 71 GHz (FR 2.2). Channel bandwidths within the bands are a maximum of 100 MHz for sub-6 GHz scaling from bands 41, 42, and 43 upward and 400 MHz for millimeter-wave. In the longer term, in V and above, channel bandwidths of 1 and 2 1

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2

5G Radio Spectrum Including RF C Band: Link Budgets and Active and Passive Device Efficiency

GHz are anticipated within 4- or 5-GHz passbands. Table 1.1 lists the 27 RAN4# 83-defined bands for FR1. The reverse-duplex bands with mobile transmit in the lower duplex are implemented to protect adjacent victim bands (services that could be desensitized by cellular networks). For example, n20 moves mobile transmit to the upper duplex to avoid interference with U.S. TV bands on the premise that since you know where base stations are, you can manage interference. However, mobiles move about, making it harder to meet required protection ratios. Existing satellite bands are all frequency division–duplexed (FDD), which means that the uplink and downlink are separated in frequency with a duplex guard band in between. This improves receive

Table 1.1  5G FR1 NR Bands in Ascending Numeric Order from 5G NR Specification TS 38.101V 15.3

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Band Number

Uplink (MHz)

Downlink (MHz)

Duplex Mode

n1

1,920–1,980

2,210–2,710

FDD

n2

1,850–1,910

1,930–1,990

FDD

n3

1710–1,785

1,805–1,880

FDD

n5

824–849

864–894

FDD

n7

2,500–2,570

2,620–2,690

FDD

n8

880–915

925–960

FDD

n20

832–862

791–821

FDD reverse duplex

n25

1,850–1,915

1,939–1,995

FDD

n28

703–748

758–803

FDD

n34

2,010–2,025

2,010–2,025

TDD

n38

2,570–2,620

2,570–2,620

TDD

n39

1,880–1,920

1,880–1,920

TDD

n40

2,300–2,400

2,300–2,400

TDD

n41

2,496–2,690

2,496–2,690

TDD

n50

1,432–1,517

1,432–1,517

TDD

n51

1,427–1,432

1,427–1,432

TDD

n66

1,710–1,780

2,210–2,200

FDD

n70

1,695–1,710

1,995–2,020

FDD

n74

1,427–1,470

1,475–1,518

FDD

n75

1,432–1,517

SDL

n76

1,427–1,432

SDL

n77

3,300–4,200

3,300–4,200

TDD

n78

3,300–3,800

3,300–3,800

TDD

n79

4,500–5,000

4,500–5,000

TDD

n80

1,710–1,785

Supplementary uplink (SUL)

n84

1,920–1,980

SUL

n85

2,496–2,690

SUL

n86

1,710–1,780

SUL

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1.2  FR1 C Band3

sensitivity but makes it harder to implement smart antenna systems that are better suited to a reciprocal radio channel in which transmit and receive frames are at the same frequency but separated in the time domain [time division duplex (TDD)]. Smart antenna systems exploit path diversity to increase capacity but require short roundtrip delays to avoid intersymbol interference particularly at high data and symbol rates. It is difficult, but not impossible, to implement TDD systems over satellite links. (See Section 1.5 on standards.) The supplementary uplink (SUL) is a new operational mode supporting a choice of lower band uplinks that can be paired with a 3.5-GHz downlink using either dual connectivity or aggregated. Five of the defined sub-6 GHz bands are described as pioneering bands intended for early deployment including n77 in C band (presently being deployed). This was proposed in Japan as an 800-MHz passband from 3.4 to 4.2 GHz, implying a bandwidth ratio of over 20%, which implies challenging and costly front-end filter specifications and/or high out-of-band emissions. N78 is more closely harmonized in different regions, including Europe. The other pioneer bands are n79 proposed by regulators in Japan, Russia, and China and N28, formerly Band 28 also known as the APT 700-MHz (Asia Pacific) band, which would be substituted by Band 20 where 28 is not available (e.g., in Europe). Theoretical calculations support a claim that a 3.5-GHz downlink with massive multiple-input multiple-output (MIMO) gain would have similar range to a 700MHz uplink from a handset, but this would be significantly dependent on the reallife efficiency of the 700-MHz antenna in the user or IOT device, the efficiency of the 3.5-GHz RX/TX path in the device, and base station power, gain, and receive sensitivity. There are also second-order and third-order relationships between the sub-gigahertz bands and Band 1 and the 3.5-GHz bands, which could potentially degrade radio performance. By the time you are reading this, C band will be most likely the most widely deployed 5G band, so it is worth taking a moment to look at the band in more detail.

1.2

FR1 C Band Confusingly, most of the 5G spectrum allocated in the latest auction round is below 4 GHz, so it is technically in S band, but C band is generically used to describe, more or less, any spectrum above 3 GHz that is being repurposed from satellite TV to 5G. The reason C band will be widely deployed is that it offers a relatively large amount of spectrum (several hundred megahertz) and that it is potentially well-suited to urban coverage with sites a kilometer apart. Also, U.S. operators have spent $80 billion on the stuff and will be asked awkward questions by their investors if they cannot find a way to get a return on the investment! In Europe and Asia, the main emphasis has been on n78 between 3.3 and 3.8 GHz. In the United States, the auctions have been n77 from 3.3 to 4.2 GHz, which includes the citizens band radio service (CBRS) band between 3.55 and 3.7 GHz that had been repurposed for 4G. The bands are both specified as TDD-optimized for a 1-km radio path—very different in time delay from a 500-km path to a spacebased eNodeB.

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4

5G Radio Spectrum Including RF C Band: Link Budgets and Active and Passive Device Efficiency

1.3

The FR2 Bands The FR2 bands in Release 15 are shown in Table 1.2. The United States, Korea, and Japan are also planning to deploy in the 28-GHz band, coexisting with existing backhaul allocations and therefore supporting inband backhaul. Other regions are proposing other bands, including 5.925–8.5 GHz and 10–10.6 GHz in Europe and 7.075–10.5 GHz and 15.35–17.3 GHz in Africa. However, there are also multiple band and technology combinations where LTE and 5G carriers are supported simultaneously either in-band or intraband. The options known as LTE and/or 5G carrier combinations (CCs) are listed in Table 1.3. This prompts some general comments. In LTE, there are presently approximately 50 band options and about 100 potential channel-aggregation options. In practice it was only economic in terms of dollar cost and performance cost to support a subset of these bands in an LTE phone or IOT device, typically 12–14 bands with limited aggregation. Release 15 and subsequent releases expanded these 50 bands to potentially 500 with over 300 aggregation combinations. This includes Ku, K, and Ka band where SAW and FBAR filters have to be replaced with ceramic filters. Ceramic filters become more manageable in terms of their real-estate footprint in a phone at these higher frequencies, but there is still a finite limit to how many filters can be included in a handheld user device or low-cost compact power efficient IOT terminal. Additionally, a decision needs to be taken on how power amplification is realized. In the 5G releases to date, networks can either be standalone, capable of working independent of a legacy LTE network, or non-standalone. In a non-standalone network, an LTE connection anchors 5G, which means that the user/IOT device is required to maintain two uplink connections, one for LTE and one for 5G NR. Since LTE and NR use different power controls, the two links must be on different amplifiers. Having two transmit amplifiers active requires more power, generates additional heat, and may cause unwanted mixing and intermodulation of the two signal paths. Other related issues include TX power and TX harmonics being reflected back into the receiver front end. Additionally, beam-shaping and beam-forming rely on accurate phase offsets being maintained across all antenna elements. This can be realized effectively across relatively narrow bandwidths on either side of a single-center frequency, but having to support many different bands, many with wide passbands, will limit range gain. The range gain and throughput calculations for 5G assume either a 16-, 32-, or 64-element antenna array in the base station. Handsets are limited to two-element Table 1.2  5G FR2 New Radio Bands in Ascending Numeric Order from 3GPP TS 38.101-1/2

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Band Number

Uplink (GHz)

Downlink (GHz)

Duplex Mode

n257

26.5–29.5

26.5–29.5

TDD

n258

24.75–27.5

24.75–27.5

TDD

n259

39.5–43.5

39.5–43.5

TDD

n260

37–40

37–40

TDD

n261

27.5–28.35 GHz

27.5–28.35 GHz

TDD

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1.3  The FR2 Bands5 Table 1.3  TE or 5G CCs CC

Total Number of Combinations Proposed

LTE_1CCNR_1CC

99

LTE_2CC_NR_1CC

101

LTE_3CC_NR_1CC

69

LTE_4CC_NR_1CC

24

LTE_5CC_NR_1CC

1

CA intraband x DL/1UL

2

CA intraband 2DL/1UL

13

LTE_1UL_NR_ULDL

4

LTE_1CC_NR_2CC

5

LTE_2CC-NR_2CC

6

LTE_3CC_NR2CC

4

LTE_4CC_NR_2CC

1

Total

329

arrays below 1 GHz due to antenna size and four for the remainder of bands up to 6 GHz. At the time of writing, eight beam-array antennas in handset form factors have not been standardized. Parallel work is ongoing on standardizing arrays for non-handset form factors. These arrays could be designed to be broadband (e.g., by switching in additional element lengths), but getting them to beam-form efficiently as well will be challenging in terms of processing overhead, size, and cost—even for networks working at Ku band and above—and very challenging for C band (3.5 GHz for example). 5G phones potentially deliver high data rates in ideal signal-to-noise environments by exploiting multiplexing gain across multiple bands. The phones will perform less well in rural and outer urban areas, but link budgets are generally based on trying to maintain data rates of at least 1 Mbps at the cell edge; 10 Mbps would make it possible to do more or less anything desired with existing phone displays. It is not impossible for satellite operators to deliver 10 Mbps to mobile smart phone users in areas where terrestrial coverage is marginal or nonexistent but the economics of doing this are as yet unproven. RF front-end engineers need to make sure that existing phones work consistently well across all terrestrial networks and an adequate subset of common radio bands. Adding satellite bands potentially makes that harder. Presently, this includes optimizing performance in the new C band allocations n77 and n78 between 3.3 and 3.8 GHz. Even if functionality from a space-based E-Node B is limited to text messaging and/or narrowband connectivity using existing bands, receiving signals from a high elevation would ideally require changes to existing antenna layouts. Given that 5G from space would by definition be a global service, then a decision will also be needed as to what bands and technology mix will be economically viable. The easiest way to study satellite 5G bands is to reorder the NR bands into low band (sub-1 GHz), mid band (1–6 GHz), and high band (above 24 GHz), as shown in Table 1.4.

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6

5G Radio Spectrum Including RF C Band: Link Budgets and Active and Passive Device Efficiency Table 1.4  NR 5G NR Low Bands