6G to Build a Sustainable Future

Mikko A. Uusitalo, Nokia Bell Labs Finland Site Lead, Head of Research Department, Nokia, Finland. Mikko was leading the European 6G Flagship project Hexa-X-II. Patrik Rugeland, Master Researcher, Ericsson Research, Sweden. Patrik was the Technical Manager for Hexa-X-II. Mauro Boldi, Project Manager, TIM, Italy. Mauro was the leader of dissemination and standardization activities for Hexa-X-II. Ahmad Nimr, Research Group Lead, TU-Dresden, Germany. Ahmad was leading the Radio Evolution and Innovation work package in Hexa-X-II.

• List of Contributors xiiiPreface xxiii1 Introduction 1Patrik Rugeland, Mikko A. Uusitalo, Sylvaine Kerboeuf, Jeroen Famaey, Stefan Wendt, Henk Wymeersch, Sokratis Barmpounakis, Hamed Farhadi, and Mauro R. Boldi1.1 Why Do We Need 6G? 21.2 Global View on Development Towards 6G 31.3 Structure of the Rest of the Book 5Disclaimer 6Acronyms and Abbreviations 6References 62 Value of 6G 9Stefan Wendt, Hanne-Stine Hallingby, Cristóbal Vinagre Zúñiga, Marja Matinmikko-Blue, Arturo Basaure, Maurizio Cecchi, Ishita Mishra, Ana Pereira, and Anastasia Yagafarova2.1 Sustainability and Values 102.2 Stakeholders in the 6G System 162.2.1 6G Use-Case Business Ecosystem Stakeholders 172.2.1.1 Business Ecosystems’ Expansion with 6G 182.2.1.2 Sustainability Risk Assessment of the 6G Use Cases 192.2.1.3 The Envisioned 6G User 192.2.1.4 Indirect 6G User Impact 202.2.1.5 Customers and Innovators as Stakeholders 202.2.1.6 Risk Mitigation 202.2.1.7 Building a Resilient 6G 212.2.2 Spectrum Ecosystem Stakeholders 212.2.3 Public Ecosystem Stakeholders 232.3 6G Use-Case Families and Use Cases 252.3.1 Immersive Experience 252.3.2 Physical Awareness 262.3.3 Digital Twins 262.3.4 Fully Connected World 272.3.5 Trusted Environments 272.3.6 Collaborative Robots 272.4 6G Use Case and Value Design | Cooperating Mobile Robots 282.4.1 Human and Planetary Goals 282.4.2 Problems to Be Solved and Challenges 292.4.3 Why 6G Is Needed 292.4.4 Example Scenarios 302.4.4.1 Cooperative Carrying with Mobile Robots 302.4.4.2 Lot-Size-1 Production 312.4.4.3 Automated Industrial Tasks 312.4.4.4 Autonomous Farming 322.4.4.5 Autonomous Construction Site 322.4.4.6 Smart Workshop 332.4.5 Deployment Aspects 342.4.5.1 Environment 342.4.5.2 Type of Deployment 342.4.5.3 Users and Devices 342.4.5.4 Constraints and Challenges 342.4.6 Requirements 352.4.7 Key Performance Indicators 352.4.8 Key Values and Key Value Indicators 372.4.9 Feedback into Technical Design 432.5 Business Models 442.5.1 Business Modelling for 6G Ecosystem 442.5.2 Business Modelling for Cooperating Mobile Robots Use Case 512.6 Conclusions 52Acknowledgement 52Acronyms and Abbreviations 53References 533 Sustainable 6G Platform 55Sylvaine Kerboeuf, Akshay Jain, Diego Lopez, Raul Munoz, Pol Alemany, Behnam Ojaghi, Luís Pedro Santos, José María Jorquera Valero, Manuel Gil Pérez, Gregorio Martínez Pérez, Pietro G. Giardina, Huy Q. Tran, Gunes Kesik, Noelia Perez Palma, Antonio Skarmeta, Pawani Porambage, Josué Castañeda Cisneros, Elham Dehghan Biyar, Ioannis Tzanettis, Grigorios Kakkavas, Anastasios Zafeiropoulos, Xosé R. Sousa, and Patrik Rugeland3.1 Sustainable 6G System: Principles and Requirements 563.1.1 Design Principles 573.1.2 Requirements 593.1.2.1 Functional Requirements 593.1.2.2 Non-functional Requirements 613.2 Blueprint of the Sustainable 6G Platform 643.2.1 E2E System Architecture 643.2.1.1 Infrastructure Layer 653.2.1.2 Network Functions Layer 663.2.1.3 Application Enablement Platform Layer 673.2.1.4 Application Layer 693.2.1.5 Pervasive Functionalities 693.2.1.6 Multistakeholder Support 713.2.2 Design Process of 6G E2E System 713.2.2.1 Top-Down Versus Bottom-Up System Design 713.2.2.2 Enablers Integration in 6G System: A Knowledge Graph-Based Approach 743.3 Multi-Stakeholder Intent-Based Service Management 763.3.1 End-to-End Multi-DSP Service Management 763.3.1.1 Multi-DSP Aggregation Service Provisioning 763.3.1.2 Multi-DSP Federation Service Provisioning 773.3.2 Intent-Based Digital Service Manager 783.3.2.1 Intent-Based Interfaces 793.3.3 Intent-Based-Specific Enablers for a Sustainable E2E Service Management 803.3.3.1 E2E Intent-Driven Service Fulfilment Management 803.3.3.2 E2E Intent-Driven Service Evaluation Management 803.3.3.3 E2E Intent-Driven Closed Loop Coordination 813.3.3.4 E2E Intent-Based Trust Management 823.4 E2E Security Concepts 823.4.1 Security Controls and Security Enablers 843.4.1.1 Physical Context Awareness 863.4.1.2 Physical Anomaly Detection 873.4.1.3 Physical Layer Deception 883.4.1.4 Transparency Services and Level of Trust Assessment 893.4.1.5 Data-Intensive E2E Security Management 913.4.1.6 DevSecOps 913.4.2 E2E 6G Security 923.4.2.1 Infrastructure Layer 923.4.2.2 Network Functions Layer 923.4.2.3 Application Enablement Platform Layer 933.4.2.4 Management and Orchestration 933.4.2.5 AI Framework 933.4.2.6 Data Framework 933.4.2.7 Multistakeholder 6G Ecosystem 933.4.2.8 Service Exposure and New 6G Services 933.5 Conclusion 94Acronyms and Abbreviations 95References 974 6G Transceiver and Radio Design 101Ahmad Nimr, Luis González, Tommy Svensson, Italo Atzeni, Jeroen Famaey, Nurul Huda Mahmood, Enrico Maria Vitucci, Gilberto Berardinelli, Claude Desset, Nuutti Tervo, George-Roberto Hotopan, Philippe Ratajczak, Davide Dardari, Sotiris Droulias, Angeliki Alexiou, Bikshapathi Gouda, Venkatesh Tentu, Charitha Madapatha, Akshay Vayal Parambath, Hao Guo, Sebastian Haas, Emil Matus, Onel L. A. López, Bikramjit Singh, Nafiseh Mazloum, Samer Nasser, Ritesh Kumar Singh, Priyesh Pappinisseri Puluckul, Riku Jäntti, Dinh-Thuy Phan-Huy, Efstathios Katranaras, Usman Virk, Pekka Kyosti, Katsuyuki Haneda, Yigit Ertugrul, Meng Li, Bilal Khan, Christos Tsokos, Osmel Martínez Rosabal, Amirhossein Azarbahram, Ling Jie, Peize Zhang, Jingyi Liao, Kalle Koskinen, Xie Boxuan, Simon Nellen, Tianwen Qian, Ahmad Mohammad, Chris Roeloffzen, Muhsin Ali, Juha-Matti Runtti, and Fengchun Zhang4.1 6G Radio Design Overview 1034.1.1 6G Radio Scenarios 1044.1.2 Radio Design Framework 1064.1.3 Flexible Radio Architecture and Deployment 1094.2 Transceivers and Antennas 1104.2.1 Novel Architectures for Transistor-Based Sub-THz Systems 1114.2.1.1 Dimensioning 1114.2.1.2 Phase Noise Mitigation Utilizing Asymmetrical LO Routing 1114.2.1.3 Antenna Integration 1134.2.2 Novel Sub-THz Transceiver Technologies 1154.2.2.1 Resonant Tunnelling Diodes 1154.2.2.2 Photonic Sub-THz Transceivers 1164.2.3 RIS Hardware Prototyping and Verification 1194.3 Channel and Hardware Modelling 1204.3.1 Short-Range Measurements and Channel Models in Industrial Scenarios 1214.3.1.1 Delay Spread Analysis 1224.3.1.2 Path-Loss Analysis 1224.3.1.3 Analysis of the Rician K-Factor 1244.3.2 Macroscopic Channel Modelling for RIS 1244.3.2.1 Fully Ray-Based Macroscopic Modelling 1254.3.3 Modelling of Sub-THz Channel Dispersion in the Presence of Beamforming 1274.3.4 Modelling of Hardware Non-Idealities 1284.3.4.1 Sub-THz Non-Idealities Modelling 1284.3.4.2 FR3 Power Amplifier Modelling 1304.4 MIMO Architectures and Transmission Schemes 1304.4.1 Hybrid Architectures Exploiting ‘Over-the-Air’ EM Signal Processing 1304.4.2 Near-Field Wavefront Engineering for Integrated Sensing and Communication 1344.4.2.1 RIS-Aided Wavefront Engineering 1344.4.2.2 Near-Field Angle-Range Localization for ISAC 1364.4.3 Massive MIMO with Low-Resolution Data Converters 1374.4.4 D-MIMO and RIS 1394.4.4.1 Centralized Versus Distributed Beamforming Design in D-MIMO 1394.4.4.2 ISAC D-MIMO, Scalable D-MIMO 1404.4.4.3 RIS-Assisted D-MIMO, RIS-Assisted IAB 1424.5 6G Devices and Infrastructure 1444.5.1 Future Directions for IoT Devices 1454.5.1.1 Energy Neutral Devices 1454.5.1.2 Enhanced LPWA 1454.5.1.3 Intelligence with TinyML 1454.5.1.4 Security and Privacy Enhancements 1454.5.2 Secure Integration of SoC Accelerators 1464.5.2.1 Secure SoC Architecture with Accelerator Integration Support 1464.5.2.2 AI and DSP Accelerator Capabilities 1474.5.3 Energy Neutral Device Design 1484.5.3.1 Energy Harvesting 1484.5.3.2 Protocols for Active Energy Neutral Devices 1504.5.3.3 Passive Energy Neutral Devices 1524.6 Conclusions 154Acronyms and Abbreviations 155References 1575 Architecture Enablers for 6G 167Mårten Ericson, Ozgur Umut Akgul, Panagiotis Botsinis, Sameh Eldessoki, Nicolas Chuberre, Dorin Panaitopol, Joachim Sachs, Hasanin Harkous, Iman Hmedoush, Luis G. Uzeda Garcia, Pere Garau Burguera, Antonio de la Oliva, János Harmatos, Halina Tarasiuk, Marcin Ziółkowski, Karol Kuczyński, Alperen Gundogan, Milan Zivkovic, Diamanti Maria, Pilar Andres Maldonado, Stefan Wänstedt, Vignesh Raman, Bassem Arar, Riccardo Bassoli, Frank H.P. Fitzek, Vasileios Tsekenis, Sokratis Barmpounakis, and Antonio Varvara5.1 Novel Services 1685.1.1 Sensing Functional Architecture 1705.1.2 Compute Offloading 1715.1.3 AI as a Service 1735.1.4 Consumer Application Function Placement Optimization 1745.2 6G Cloud-Native Architecture 1765.2.1 Modular Network Architecture for 6G 1765.2.2 Inter-module Interactions and Interfaces 1785.2.3 Integration of Extreme Edge 1795.3 Flexible Networks 1805.3.1 Subnetworks 1815.3.2 Multi-connectivity 1825.3.3 5G–6G Spectrum Co-existence: Multi-RAT Spectrum Sharing 1855.4 Non-terrestrial Networks 1865.4.1 Rationale for NTN in 6G 1865.4.2 NTN Deployment Scenarios 1875.4.2.1 Frequency Band of the Service Link 1895.4.2.2 Radio Cells 1905.4.3 Impact on 6G System Architecture 1915.4.4 Support of NTN-TN Integration 1915.4.4.1 Ubiquitous Connectivity 1915.4.4.2 Resiliency 1925.4.4.3 Network Energy Efficiency/Sustainability 1925.4.4.4 Spectrum Usage Efficiency 1925.4.5 On-Board Edge Capabilities 1925.5 Dependable Networking 1935.5.1 Enablers for Dependable Networking 1945.5.1.1 Performance Observability and Predictability 1945.5.1.2 Dependable Edge Cloud Integration 1955.5.1.3 Packet Delay Correction for Deterministic Delay Performance 1965.5.1.4 Network Programmability and Communication–Control–Compute Co-design 1965.5.1.5 Bringing Dependability to the Multi-domain Multi-technology Data Plane 1975.5.2 Architecture Support for Dependable End-to-End Communication with 6G 1985.6 Radio Protocols 2005.6.1 Radio Control Plane 2015.6.2 Radio User Plane 2025.6.3 Mobility Procedures 2045.6.4 App-Network Interactions for Service Differentiation and QoS/QoE Management 2045.7 Quantum-Enhanced Network Functionalities 2055.8 Conclusions 207Acronyms and Abbreviations 209References 2126 6G Intelligence 217Hamed Farhadi, Dani Korpi, Nabeel Nisar Bhat, Pawani Porambage, Halina Tarasiuk, Marcin Ziółkowski, Karol Kuczyński, José Miguel Mateos Ramos, Christian Häger, Henk Wymeersch, Ricard Vilalta, Merve Saimler, Leyli Karacay, and Milan Zivkovic6.1 The Motivations for AI/ML in 6G 2176.1.1 The Needs for Data-Driven Architecture 2176.1.2 The Needs for AI/ML for Physical Layer Signal Processing 2196.1.3 The Needs for AI-Driven Management and Orchestration 2216.1.4 The Needs for Trustworthy AI/ML and AI/ML for 6G Trustworthiness 2226.2 6G System Blueprint: AI/ML-Specific View 2226.3 AI-Native Architecture 2256.3.1 DataOps 2256.3.2 MLOps 2276.3.3 AI as a Service 2296.4 AI-Driven Radio Air Interface 2326.4.1 AI-Driven Methods for Hardware Impairment Compensation for Communication 2326.4.2 End-to-End Optimized Physical Layer Using AI/ML Algorithms 2336.4.3 Model-Based Learning for Hardware Impairment Compensation in ISAC 2346.4.4 Data-Driven Sensing with Wireless Signals 2356.5 Smart Network Management 2356.5.1 AI-Based Solutions for Resource Allocation 2356.5.2 Network Digital Twins 2366.5.3 Multi-agent-Based Solutions for Distributed Services Orchestration 2376.5.4 AI-Enabled Network Management 2386.5.5 Causal AI for Intent-Based Management 2396.6 AI/ML and Trustworthiness for 6G 2406.6.1 AI/ML for Trustworthiness 2406.6.2 Trustworthy AI/ML for 6G 2426.7 An Overview of AI/ML Standardizations 2446.7.1 AI/ML Standardization in 3GPP SA 2 2446.7.2 AI/ML Standardization in 3GPP SA 5 2456.7.3 AI/ML Standardization in 3GPP SA 6 2456.7.4 AI/ML Standardization for Air Interface in 3GPP RAN1/RAN 2 2466.7.5 AI/ML Standardization for Air Interface in O-RAN 2466.8 Conclusion 246Acknowledgment 247Acronyms and Abbreviations 247References 2497 Integrated Sensing and Communication 253Henk Wymeersch, Sami Mekki, Stefan Wänstedt, Athanasios Stavridis, Kawon Han, George C. Alexandropoulos, Benoît Denis, Sharief Saleh, Hui Chen, Yu Ge, Sokratis Barmpounakis, Vasileios Tsekenis, Rreze Halili, Rafael Berkvens, Pablo Picazo-Martínez, Giyyarpuram Madhusudan, Henry Blue, Nhan Thanh Nguyen, Markku Juntti, Musa Furkan Keskin, Francesca Costanzo, and Christos Masouros7.1 The Role of ISAC in 6G 2547.1.1 ISAC Use Cases 2547.1.2 ISAC Requirements and Metrics 2567.1.3 Global View on ISAC 2577.1.4 Foundations of ISAC 2587.1.4.1 Sensing Configurations 2587.1.4.2 Integrating Sensing into Communication 2597.2 The ISAC Architecture 2607.2.1 Sensing Network Functions and Procedures 2617.2.2 Centralized and Distributed Processing 2627.2.2.1 Data Representation and Sharing 2637.2.2.2 Tracking and Handover of Passive Targets 2647.2.3 Role of AI/ML and Semantics in ISAC 2657.2.3.1 AI/ML in ISAC 2657.2.3.2 Semantic Communication in ISAC 2667.3 The ISAC Physical Layer 2687.3.1 Waveforms for ISAC 2687.3.1.1 MIMO-OFDM for ISAC 2687.3.1.2 Beamforming for ISAC 2697.3.1.3 Emerging Waveforms for ISAC: OTFS and Beyond 2707.3.2 Signal Processing for Sensing 2717.3.2.1 Generic ISAC Signal Processing 2717.3.2.2 Examples Deployment Scenarios 2737.4 ISAC Hardware Considerations 2757.4.1 Hardware Impairments and Calibration 2757.4.1.1 Hardware Impairments 2757.4.1.2 Impact of Hardware Impairments 2767.4.1.3 Mitigation of Hardware Impairments 2777.4.2 Self-Interference Suppression 2787.4.2.1 SI Mitigation Mechanisms 2797.4.2.2 Simultaneous DL Data Communication and Monostatic Sensing 2807.4.3 Synchronization Requirements for ISAC 2817.4.3.1 Impact of Synchronization on Monostatic ISAC 2817.4.3.2 Impact of Synchronization on Bistatic ISAC 2827.4.3.3 Impact of Synchronization on Distributed ISAC 2837.5 Conclusion 284Acknowledgement 284Acronyms and Abbreviations 285References 2868 Early Validation of 6G Concepts 293Sokratis Barmpounakis, Vasileios Tsekenis, Vasiliki Lamprousi, Pietro G. Giardina, Ioannis Tzanettis, Grigorios Kakkavas, Anastasios Zafeiropoulos, Panagiotis Demestichas, Ricard Vilalta, Daniel Adanza, Raul Muñoz, Pol Alemany, and Rafael Pires8.1 PoC Components in the E2E 6G System Blueprint 2958.2 KPIs Related to the Validation Activities 2978.3 Social, Environmental, and Economic Sustainability Aspects 2988.4 Validation Use Cases 2998.4.1 The Cobot-Powered Warehouse Inventory Management Use Case 2998.4.2 Zero-Touch Cobot-Based Video Surveillance Use Case 3018.4.2.1 Edge Computing and Orchestration Layer 3028.4.2.2 Cobot Surveillance System (Robot Layer) 3058.4.2.3 VR Control and Monitoring Layer 3068.5 System PoC Enablers 3078.5.1 Advanced Management and Orchestration Mechanisms: Trust- and Energy-Driven Functionality Allocation 3078.5.1.1 Implementation (Energy-Driven Optimization) 3078.5.1.2 Implementation (Trust-Driven Optimization) 3098.5.2 Advanced Management and Orchestration Mechanisms: Zero-Touch Automation 3118.5.3 Trustworthy Flexible Topologies and Beyond Communication Aspects 3148.5.4 AI-Assisted E2E Lifecycle Management of a 6G Latency-Sensitive Service 3178.6 Evaluation Results 3208.6.1 Trust- and Energy-Driven Functionality Allocation Evaluation Results 3208.6.2 Trustworthy Flexible Topologies and Beyond Communication Results 3248.6.3 AI-Assisted E2E Lifecycle Management of a 6G Latency-Sensitive Service Evaluation Results 3248.6.4 Service Migration-Related Evaluation Results 3268.6.5 Intent-Based Networking Evaluation Results 3278.7 Conclusion 330Acronyms and Abbreviations 331References 3329 Path Towards 6G 335Ishita Mishra, Toon Norp, Per Hjalmar Lehne, Bahare M. Khorsandi, Ricard Vilalta, Alexandros Kaloxilos, Patrik Rugeland, and Mauro R. Boldi9.1 Migration from 5G to 6G and Gaps 3359.2 Global 6G Initiatives 3379.2.1 European Priorities for 6G Development 3379.2.2 European National Platforms View 3409.2.3 North America: Strengthening 6G Innovation Through Strategic Alliances 3429.2.4 South America: Advancing 6G for Emerging Markets 3439.2.5 Asia-Pacific: Key Contributions to 6G Development 3439.2.6 Initiatives Towards Openness 3449.3 6G Industrial Exploitation and Market Aspects 3459.3.1 Industry’s Main Interests in 6G 3459.3.2 Anticipated Impact from European R&I on 6G 3469.3.3 Investigating the Exploitation Potential 3469.3.4 6G Market Prospects 3489.4 Next Steps for 6G Standardization 3489.4.1 Standardization and Industrial Fora 3499.4.2 Roadmap and Next Steps 3499.5 Key Challenges and Future Directions 351Acronyms and Abbreviations 351References 35210 Conclusion 355Patrik Rugeland, Mikko A. Uusitalo, and Mauro R. BoldiIndex 357