High-Altitude Platforms for Wireless Communications

Dr. Aragón-Zavala graduated from Tecnológico de Monterrey, Campus Querétaro as Electronics and Communications Engineer in December 1991. In 1998 he received his MSc in Satellite Communication Engineering from the University of Surrey, and in 2003 his PhD in Antennas and Propagation at the same university. He has worked as an engineer and consultant in the industry, and since 2003, Dr. Aragón-Zavala is the Academic Director of the former IEC and ISE undergraduate programs at the Tecnológico de Monterrey Campus Querétaro, and is in charge of ITE (all Electronic Engineering degrees). His research interests include: mobile communications, satellite systems, high-altitude platform systems, antenna design and indoor propagation.Dr José Luis Cuevas-Ruiz received his PhD from Universitat Politecnica de Catalunya in 2005, where he was involved in the HeliNet and CAPANINA projects related to high-altitude platform systems. His research interests include HAPS, wireless communications and channel modelling. He has been with Tecnológico de Monterrey Campus Estado de México since 1999, and currently he is Head of the Communications Research group at Campus Estado de México. Dr José Antonio Delgado-Penin is a full professor at the Department of Signal Theory and Communications, at Universitat Politécnica de Catalunya, Spain since 1984. His Academic, technical and research activities have been at Philips N.V, ETSITM, Polito, CNET, Univ. Manchester and UCLA amongst others, all in the field of Telecommunications engineering.

• Preface xiii1 Introduction 11.1 What is a HAPS? 11.2 Structure of the Book 3References 42 Overview on HAPS 52.1 HAPS System Concepts 52.1.1 HAPS Definition and Features 52.1.2 Components of HAPS Communication Systems 72.1.2.1 Stratospheric Segment 72.1.2.2 Ground Segment 82.2 Radio Regulations for HAPS 92.3 Applications and Services 112.3.1 Selection of Possible Applications 112.3.2 Application and Service Requirements 122.3.3 Narrowband Services 122.3.4 Broadband Services 132.4 HAPS Networks 142.5 Terrestrial, Satellite and Stratospheric Communication Systems: A Comparison 152.6 Survey of the Evolution and State-of-the-Art of HAPS in the World 172.6.1 North American HAPS Projects 172.6.1.1 SHARP 172.6.1.2 Sky Station 202.6.1.3 HALO-Proteus 212.6.1.4 Pathfinder, Pathfinder Plus, HELIOS, SkyTower 212.6.2 European Projects and Activities on HAPS 232.6.2.1 HALE 242.6.2.2 STRATOS 242.6.2.3 HeliNet 252.6.2.4 CAPANINA 262.6.2.5 COST 297 – HAPCOS 272.6.2.6 USE HAAS 292.6.2.7 European Union Research Thematic Networks 292.6.3 Asia-Pacific Projects and Activities on HAPS 302.6.3.1 Japanese Activities 302.6.3.2 Korean Activities 312.6.3.3 International Cooperation Activities in Malaysia 32References 333 Propagation and Channel Modelling 373.1 Introduction 373.2 An Overview of Propagation Phenomena 383.2.1 Free Space Loss 383.2.2 Multipath 383.2.3 Rain Attenuation 413.2.4 Gaseous Absorption 423.2.5 Scintillation 443.3 Channel Modelling 483.3.1 Geometric Characterisation 493.3.2 Statistical Characterisation 523.3.3 UHF Channel Models 553.3.3.1 Wideband Models 553.3.3.2 Switched-Channel Models 583.3.3.3 Markov Chains 593.3.3.4 Lutz Model 623.3.3.5 Semi-Markovian Processes 643.3.3.6 Switched Broadband Channel Models 663.3.3.7 Politecnico di Torino (Polito) Multipath Channel Model 693.3.4 SHF Channel Models 703.3.4.1 Clear Sky 703.3.4.2 Rain 723.3.4.3 Time Series 773.4 Fading Mitigation Techniques 823.4.1 Power Control 843.4.1.1 Uplink Power Control 843.4.1.2 Downlink Power Control 853.4.1.3 On-board Beam Shaping 863.4.2 Adaptive Methods 863.4.2.1 Adaptive Coding 863.4.2.2 Adaptive Modulation 873.4.2.3 Digital Transmission Rate Reduction 913.4.3 Diversity 913.4.3.1 Site Diversity 913.4.3.2 Platform Diversity 923.4.3.3 Frequency Diversity 923.4.3.4 Time Diversity 933.4.4 Fading Detection 943.4.4.1 Open Loop 943.4.4.2 Closed Loop 943.4.4.3 Hybrid Loop 953.5 Conclusions 95References 954 Antennas for HAPS 994.1 Introduction 994.2 Antenna Requirements 1004.2.1 Physical Requirements 1004.2.2 Gain, Directivity and Efficiency 1024.2.3 Sidelobe Performance 1044.2.4 Footprint 1044.2.5 Beam Steering 1054.2.6 Scan Range 1064.2.7 Coverage Area 1074.2.8 Multiple Beam Functionality 1074.2.9 Operating Frequency 1074.3 Antenna Types for High-Altitude Platforms 1084.3.1 Phased-Array Antennas 1084.3.2 Aperture Antennas 1104.3.2.1 Lens Antennas 1104.3.2.2 Parabolic Reflectors 1134.3.2.3 Horn Antennas 1164.3.3 Broadband Printed Array Antennas 1164.3.4 Smart (Adaptive) Antennas 1194.4 Antenna Design Recommendations at Operating Frequencies Allocated to HAPS 1204.4.1 Antennas for IMT-2000 Frequency Band (2.1 GHz) 1204.4.2 Antennas for the Ka Frequency Band (27/31 GHz) 1224.4.3 Antennas for the 47/49 GHz Frequency Band 1244.5 Steering Mechanisms 1244.5.1 Axis Control Gimbals 1254.5.2 Antenna Positioning Systems 1264.5.3 Research on Antenna Gimbals 1274.6 Beamforming 1284.6.1 HAPS-Based Beamforming 1294.6.1.1 Adaptive Methods 1294.6.1.2 Non-adaptive Methods 1304.6.2 Ground-Based Beamforming 1364.7 Challenges 136References 1375 Communication Systems Based on HAPS 1415.1 Components of HAPS Communication Systems 1415.1.1 Stratospheric Segment 1415.1.1.1 Platforms 1425.1.1.2 Telecommunications Payload 1435.1.1.3 Telemetry, Tracking and Command 1465.1.1.4 Attitude and Stabilisation Control 1485.1.1.5 Electrical Power Subsystem 1505.1.2 Ground Segment 1535.1.2.1 Antennas 1545.1.2.2 Low-noise Amplifier 1545.1.2.3 High-power Amplifier 1545.1.2.4 Software 1545.1.2.5 People 1555.2 Spectrum Allocation for HAPS 1555.3 HAPS Link Budget 1595.3.1 Uncoded Digital Transmission Analysis 1605.3.1.1 Uplink 1625.3.1.2 Transponder 1635.3.1.3 Downlink 1645.3.2 Coded Digital Transmission Features 1645.3.3 IMT-2000 (2.1 GHz) Link Budgets 1675.3.3.1 HAPS for IMT-2000 Systems 1675.3.3.2 CDMA HAPS Link Budget for Voice 1715.3.3.3 CDMA HAPS Link Budget for High-Speed Data Services 1745.3.4 Ka-Band (27/31 GHz) Link Budgets 1745.3.4.1 Clear Sky 1775.3.4.2 Rain 1795.3.5 SHF-Band (47/49 GHz) Link Budget 1795.3.5.1 Frequency Planning 1815.3.5.2 Transmission Characteristics of the Platform Station 1825.3.5.3 User Terminals and Ground Stations 1825.3.5.4 Radioelectric Emission Characteristics of HAPS Communication Systems 1825.3.5.5 Link Budget Analysis 1835.3.6 Link Budget Comparison 1845.4 Conclusions 185References 1856 HAPS Networks 1896.1 Introduction 1896.2 Network Topologies 1896.2.1 Point-To-Point Deployment Topology 1906.2.2 Point-To-Multipoint Deployment Topology 1906.2.3 Multipoint-To-Multipoint Deployment Topology 1916.2.4 Hybrid Deployment Topology 1916.3 Network Architectures for Service Candidates 1926.3.1 Ring-Shaped Cell Clustering 1926.3.2 Cell Scanning 1936.3.3 Multiple-Beam Mobile Platform Scenario 1936.3.4 Macrocell–Microcell–HAPS Topology 1936.3.5 Cell Sectorisation Architecture 1946.3.6 Standalone Platform 1956.3.7 Network of Platforms Connected Via Ground Stations 1966.3.8 Network of Platforms Connected Via Interplatform Links 1976.3.9 Integrated Terrestrial–HAPS–Satellite Networks 1986.3.9.1 Use of HAPS for Interactive Digital Broadcast System 2006.3.9.2 Symmetric DVB-RCH Configuration 2006.3.9.3 Asymmetric DVB-RCH Configuration 2006.4 Interworking Requirements 2016.4.1 Cell Planning 2026.4.2 Call Admission Control 2036.4.3 Handover Issues 2036.5 HAPS Networks for Other Applications 2046.5.1 Navigation 2046.5.2 Emergency Services 2056.6 Free Space Optical Links in HAPS 2066.6.1 Stratospheric Relay and Integrated Satellite–HAPS Using Optical Links 2066.6.2 Optical Satellite Downlinks for Earth Observation Satellites Using HAPS 2086.7 Resource Management 2086.7.1 Resource Allocation 2086.7.1.1 Area-Based Fixed Channel Assignment Scheme 2096.7.1.2 Uniform Fixed Channel Assignment Scheme 2096.7.2 Call Admission Control 2106.7.3 Medium Access Techniques 2116.8 HAPS as Part of Integrated Communication Networks 2126.8.1 2G Cellular Systems: GSM 2126.8.2 3G Cellular Systems: IMT-2000 213References 2137 The Future 2177.1 Introduction 2177.2 Challenges and Opportunities for Civil UAS 2187.3 Applications for Civil UAS 2197.3.1 General Applications 2197.3.2 Telecommunications Applications 2207.4 Requirements for the Future of the Civil UAS 2227.4.1 Aeronautical Regulations 2227.4.2 Spectrum Regulation 2237.5 Technological Trends 2247.5.1 Platform Technologies 2247.5.2 Telecommunications Technologies 2267.6 Technological Challenges for HAPS Applied to Wireless Communications 2277.6.1 Radiowave Propagation Models at Millimetre-Wave Bands 2277.6.2 Fade Mitigation Techniques 2277.6.3 Forward Error Control and Modulation Techniques 2277.6.4 Interference Management 2287.6.5 Handover Issues 2287.6.6 In-Building Penetration 2287.6.7 Networking Issues 2287.6.8 Antenna Technology 2297.7 Conclusions 229References 230Glossary 233Index 237