Dr. Vimal Bhatia received the Ph.D. degree from the University of Edinburgh, Edinburgh, U.K., in 2005. He is currently a Professor with the Indian Institute of Technology (IIT) Indore, and Adjunct Faculty Member with IIT Delhi and IIIT Delhi, India. He was with various IT companies for over 11 years both in India and U.K. He is a PI/Co-PI/Coordinator for external projects with funding of over U.S. 20 million from MeitY, DST, UKIERI, MoE, AKA, IUSSTF, and KPMG. He was the Founder and the Head of the Center for Innovation and Entrepreneurship, the Associate Dean of Research and Development, and the Dean of Academic Affairs. He is also an Associate Editor of IETE Technical Review, Frontiers in Communications and Networks, Frontiers in Signal Processing, IEEE WIRELESS COMMUNICATIONS LETTERS, and IEEE TRANSACTIONS ON GREEN COMMUNICATIONS AND NETWORKING. He recognized as World’s Top 2% Scientists by Stanford University.Dr. Zhiguo Ding received his Ph.D degree from Imperial College London in 2005. He is currently a Professor in Communications at Khalifa University, and has also been affiliated with the University of Manchester and Princeton University. He is serving as an Area Editor for the IEEE Transactions on Wireless Communications, and IEEE Open Journal of the Communications Society, an Editor for IEEE Transactions on Vehicular Technology. He recently received the EU Marie Curie Fellowship 2012-2014, the Top IEEE TVT Editor 2017, Friedrich Wilhelm Bessel Research Award 2020, and IEEE VTS Best Magazine Paper Award 2023. He is a Fellow of the IEEE, and a Web of Science Highly Cited Researcher in two categories 2022.Dr. Keshav Singh received the Ph.D. degree in Communication Engineering from National Central University, Taiwan, in 2015. He currently works at the Institute of Communications Engineering, National Sun Yat-sen University, Taiwan, as an Associate Professor. He serves as leading guest editor of IEEE Transactions on Green Communications and Networking and IEEE Internet of Things Journal. He leads research in the areas of green communications, NOMA, machine learning, ISAC, and large intelligent surface-assisted communications.Amit Baghel completed M. Tech from the ABV-IIITM Gwalior, India, in 2015. He is currently pursuing a PhD from the IIT Indore, India, and is also working as an Assistant Professor at Jabalpur Engineering College, Jabalpur, India. Prior to his academic career, he worked as a System Engineer at Infosys Technology Limited from March 2009 to June 2011. His current research interests include NOMA, heterogeneous networks, stochastic geometry, MIMO, and SWIPT.Dr. Abhinav Singh Parihar completed Ph.D. degree from the IIT Indore, India, in 2024. He is currently working as an Assistant Professor with the Department of Electronics and Communication Engineering, IIIT Bhopal. He worked as a Lecturer at Government Polytechnic College Rajgarh, Madhya Pradesh, and a Postdoctoral Fellow at the National Sun Yat-sen University, Kaohsiung, Taiwan. His current research interests include NOMA, heterogeneous networks, stochastic geometry, MIMO, ISAC, and RIS.Deepak Kumar received the Ph.D. degree from the IIT Indore, India, in 2023. He is currently working as a Post-Doctoral Researcher at Khalifa University, Abu Dhabi, UAE.  From May 2023 to April 2025, he was working as a Post-Doctoral Researcher at University of Oulu, Finland. His research focuses on the performance evaluation of cooperative networks, NOMA, RIS, and ISAC systems.

• Chapter 1 Introduction.- 1.1 Overview.- 1.1.1 History: From 1G to 6G.- 1.1.2 Requirements and application of 6G.- 1.2 An Overview of Heterogeneous Networks.- 1.2.1 Architecture of Heterogeneous Networks.- 1.3 An overview of NOMA.- 1.3.1 NOMA Architecture.- 1.3.2 Superposition coding.- 1.3.3 Successive interference cancellation.- 1.3.4 NOMA in Downlink Transmission.- 1.4 An Introduction of SWIPT.- 1.4.1 Definition and overview.- 1.4.2 Importance in Modern Wireless Networks.- 1.4.3 SWIPT Architecture.- 1.4.3.1 Time Switching (TS).- 1.4.3.2 Power Splitting (PS).- 1.4.3.3 Hybrid Architectures.- 1.5 An Introduction of RIS.- 1.5.1 Definition and overview.- 1.5.2 Role in Modern Wireless Communication.- 1.5.3 Fundamental Concepts of RIS.- 1.5.3.1 Structure and Functionality.- 1.5.3.2 Physics of Metasurfaces.- 1.5.3.3 Beamforming and Phase Shifting.- 1.5.4 Integration of RIS in Wireless Networks.- 1.5.4.1 Benefits of RIS in 5G and Beyond.- 1.5.4.2 Comparison with Traditional Techniques.- Chapter 2 Joint Impact of HPA Non-linearity and Imperfect SIC in NOMA Enabled HCN.- 2.1 Introduction and System Model.- 2.2 Instantaneous received SINR.- 2.2.1 A typical user connected to MBS tier.- 2.2.2 A typical user connected to PBS tier (PU) without NOMA.- 2.2.3 PU (NOMA with perfect SIC).- 2.2.4 PU (NOMA with i-SIC).- 2.2.5 PU (NOMA with non-linear HPA).- 2.2.6 PU (NOMA with i-SIC & non-linear HPA).- 2.3 Performance Matrix.- 2.3.1 Outage Probability.- 2.3.2 Asymptotic Outage Probability.- 2.3.3 Ergodic Rate Analysis.- 2.3.4 System throughput.- 2.3.5 Energy Efficiency.- 2.4 Results and Discussions.- Chapter 3 Performance of NOMA-empowered HCN: A Stochastic Geometry Approach Considering Imperfect SIC and CSI.- 3.1 Introduction and System Model.- 3.2 Instantaneous received SINR.- 3.2.1 MBS User's SINR.- 3.2.2 PBS User's SINR (i-CSI, excluding NOMA).- 3.2.3 PBS User's SINR (i-CSI, NOMA with i-SIC).- 3.3 Performance Matrix.- 3.3.1 Outage Probability.- 3.3.2 Asymptotic Outage Probability.- 3.3.3 System throughput.- 3.3.4 Energy Efficiency.- 3.4 Results and Discussions.- Chapter 4 SWIPT Enabled Cooperative NOMA in Heterogeneous Networks.- 4.1 Network Model.- 4.1.1 Spatial Distribution of BS.- 4.1.2 Signal Model.- 4.1.3 Association Criteria.- 4.2 Carrier Sensing.- 4.2.1 Modelling BS tiers.- 4.2.2 Neighborhood Success Probability.- 4.2.3 Repulsive point process.- 4.3 Comparison of PS and TS architectures.- 4.4 Power Beacon and Intermediate Node.- 4.5 Performance Metrics.- 4.5.1 Outage Probability.- 4.5.2 System Throughput.- 4.5.3 Energy Efficiency.- 4.6 Results and Discussions.- Chapter 5 Performance of HCN with Non-Linear HPA in SWIPT-Enabled Cooperative-NOMA.- 5.1 Introduction and System Model.- 5.2 Multi-tier SINR analyses.- 5.2.1 MBS user’s SINR.- 5.2.2 PBS user’s SINR excluding NOMA.- 5.2.3 PBS user’s SINR (NOMA with non-linear PA and Energy Harvesting).- 5.2.3.1 Energy Harvesting.- 5.2.3.2 Bussgang’s linearization theory.- 5.2.3.3 Information Transmission.- 5.3 Performance Matrix.- 5.3.1 Outage Probability.- 5.3.4 System throughput.- 5.3.5 Energy Efficiency.- 5.4 Results and Discussions.- Chapter 6 Performance of RIS-Aided NOMA Network.- 6.1 System Model.- 6.2 Signal Model.- 6.3 Instantaneous received SNR.- 6.4 Performance Matrix.- 6.4.1 Outage Probability.- 6.4.2 Asymptotic Outage Probability.- 6.4.3 Ergodic Capacity.- 6.4.4 Average Symbol Error Rate.- 6.4.4.1 Rectangular QAM.- 6.4.4.2 Cross QAM.- 6.4.4.3 Hexagonal QAM.- 6.5 Results and Discussions.- Chapter 7 Conclusion and Future Works.- 7.1 Conclusion.- 7.2 Future Works.

Dr. Vimal Bhatia received the Ph.D. degree from the University of Edinburgh, Edinburgh, U.K., in 2005. He is currently a Professor with the Indian Institute of Technology (IIT) Indore, and Adjunct Faculty Member with IIT Delhi and IIIT Delhi, India. He was with various IT companies for over 11 years both in India and U.K. He is a PI/Co-PI/Coordinator for external projects with funding of over U.S. 20 million from MeitY, DST, UKIERI, MoE, AKA, IUSSTF, and KPMG. He was the Founder and the Head of the Center for Innovation and Entrepreneurship, the Associate Dean of Research and Development, and the Dean of Academic Affairs. He is also an Associate Editor of IETE Technical Review, Frontiers in Communications and Networks, Frontiers in Signal Processing, IEEE WIRELESS COMMUNICATIONS LETTERS, and IEEE TRANSACTIONS ON GREEN COMMUNICATIONS AND NETWORKING. He recognized as World’s Top 2% Scientists by Stanford University.Dr. Zhiguo Ding received his Ph.D degree from Imperial College London in 2005. He is currently a Professor in Communications at Khalifa University, and has also been affiliated with the University of Manchester and Princeton University. He is serving as an Area Editor for the IEEE Transactions on Wireless Communications, and IEEE Open Journal of the Communications Society, an Editor for IEEE Transactions on Vehicular Technology. He recently received the EU Marie Curie Fellowship 2012-2014, the Top IEEE TVT Editor 2017, Friedrich Wilhelm Bessel Research Award 2020, and IEEE VTS Best Magazine Paper Award 2023. He is a Fellow of the IEEE, and a Web of Science Highly Cited Researcher in two categories 2022.Dr. Keshav Singh received the Ph.D. degree in Communication Engineering from National Central University, Taiwan, in 2015. He currently works at the Institute of Communications Engineering, National Sun Yat-sen University, Taiwan, as an Associate Professor. He serves as leading guest editor of IEEE Transactions on Green Communications and Networking and IEEE Internet of Things Journal. He leads research in the areas of green communications, NOMA, machine learning, ISAC, and large intelligent surface-assisted communications.Amit Baghel completed M. Tech from the ABV-IIITM Gwalior, India, in 2015. He is currently pursuing a PhD from the IIT Indore, India, and is also working as an Assistant Professor at Jabalpur Engineering College, Jabalpur, India. Prior to his academic career, he worked as a System Engineer at Infosys Technology Limited from March 2009 to June 2011. His current research interests include NOMA, heterogeneous networks, stochastic geometry, MIMO, and SWIPT.Dr. Abhinav Singh Parihar completed Ph.D. degree from the IIT Indore, India, in 2024. He is currently working as an Assistant Professor with the Department of Electronics and Communication Engineering, IIIT Bhopal. He worked as a Lecturer at Government Polytechnic College Rajgarh, Madhya Pradesh, and a Postdoctoral Fellow at the National Sun Yat-sen University, Kaohsiung, Taiwan. His current research interests include NOMA, heterogeneous networks, stochastic geometry, MIMO, ISAC, and RIS.Deepak Kumar received the Ph.D. degree from the IIT Indore, India, in 2023. He is currently working as a Post-Doctoral Researcher at Khalifa University, Abu Dhabi, UAE.  From May 2023 to April 2025, he was working as a Post-Doctoral Researcher at University of Oulu, Finland. His research focuses on the performance evaluation of cooperative networks, NOMA, RIS, and ISAC systems.

• Chapter 1 Introduction.- 1.1 Overview.- 1.1.1 History: From 1G to 6G.- 1.1.2 Requirements and application of 6G.- 1.2 An Overview of Heterogeneous Networks.- 1.2.1 Architecture of Heterogeneous Networks.- 1.3 An overview of NOMA.- 1.3.1 NOMA Architecture.- 1.3.2 Superposition coding.- 1.3.3 Successive interference cancellation.- 1.3.4 NOMA in Downlink Transmission.- 1.4 An Introduction of SWIPT.- 1.4.1 Definition and overview.- 1.4.2 Importance in Modern Wireless Networks.- 1.4.3 SWIPT Architecture.- 1.4.3.1 Time Switching (TS).- 1.4.3.2 Power Splitting (PS).- 1.4.3.3 Hybrid Architectures.- 1.5 An Introduction of RIS.- 1.5.1 Definition and overview.- 1.5.2 Role in Modern Wireless Communication.- 1.5.3 Fundamental Concepts of RIS.- 1.5.3.1 Structure and Functionality.- 1.5.3.2 Physics of Metasurfaces.- 1.5.3.3 Beamforming and Phase Shifting.- 1.5.4 Integration of RIS in Wireless Networks.- 1.5.4.1 Benefits of RIS in 5G and Beyond.- 1.5.4.2 Comparison with Traditional Techniques.- Chapter 2 Joint Impact of HPA Non-linearity and Imperfect SIC in NOMA Enabled HCN.- 2.1 Introduction and System Model.- 2.2 Instantaneous received SINR.- 2.2.1 A typical user connected to MBS tier.- 2.2.2 A typical user connected to PBS tier (PU) without NOMA.- 2.2.3 PU (NOMA with perfect SIC).- 2.2.4 PU (NOMA with i-SIC).- 2.2.5 PU (NOMA with non-linear HPA).- 2.2.6 PU (NOMA with i-SIC & non-linear HPA).- 2.3 Performance Matrix.- 2.3.1 Outage Probability.- 2.3.2 Asymptotic Outage Probability.- 2.3.3 Ergodic Rate Analysis.- 2.3.4 System throughput.- 2.3.5 Energy Efficiency.- 2.4 Results and Discussions.- Chapter 3 Performance of NOMA-empowered HCN: A Stochastic Geometry Approach Considering Imperfect SIC and CSI.- 3.1 Introduction and System Model.- 3.2 Instantaneous received SINR.- 3.2.1 MBS User's SINR.- 3.2.2 PBS User's SINR (i-CSI, excluding NOMA).- 3.2.3 PBS User's SINR (i-CSI, NOMA with i-SIC).- 3.3 Performance Matrix.- 3.3.1 Outage Probability.- 3.3.2 Asymptotic Outage Probability.- 3.3.3 System throughput.- 3.3.4 Energy Efficiency.- 3.4 Results and Discussions.- Chapter 4 SWIPT Enabled Cooperative NOMA in Heterogeneous Networks.- 4.1 Network Model.- 4.1.1 Spatial Distribution of BS.- 4.1.2 Signal Model.- 4.1.3 Association Criteria.- 4.2 Carrier Sensing.- 4.2.1 Modelling BS tiers.- 4.2.2 Neighborhood Success Probability.- 4.2.3 Repulsive point process.- 4.3 Comparison of PS and TS architectures.- 4.4 Power Beacon and Intermediate Node.- 4.5 Performance Metrics.- 4.5.1 Outage Probability.- 4.5.2 System Throughput.- 4.5.3 Energy Efficiency.- 4.6 Results and Discussions.- Chapter 5 Performance of HCN with Non-Linear HPA in SWIPT-Enabled Cooperative-NOMA.- 5.1 Introduction and System Model.- 5.2 Multi-tier SINR analyses.- 5.2.1 MBS user’s SINR.- 5.2.2 PBS user’s SINR excluding NOMA.- 5.2.3 PBS user’s SINR (NOMA with non-linear PA and Energy Harvesting).- 5.2.3.1 Energy Harvesting.- 5.2.3.2 Bussgang’s linearization theory.- 5.2.3.3 Information Transmission.- 5.3 Performance Matrix.- 5.3.1 Outage Probability.- 5.3.4 System throughput.- 5.3.5 Energy Efficiency.- 5.4 Results and Discussions.- Chapter 6 Performance of RIS-Aided NOMA Network.- 6.1 System Model.- 6.2 Signal Model.- 6.3 Instantaneous received SNR.- 6.4 Performance Matrix.- 6.4.1 Outage Probability.- 6.4.2 Asymptotic Outage Probability.- 6.4.3 Ergodic Capacity.- 6.4.4 Average Symbol Error Rate.- 6.4.4.1 Rectangular QAM.- 6.4.4.2 Cross QAM.- 6.4.4.3 Hexagonal QAM.- 6.5 Results and Discussions.- Chapter 7 Conclusion and Future Works.- 7.1 Conclusion.- 7.2 Future Works.