mobile networks

sum rate

cellular networks

mobile network

successive interference cancellation

multiple access noma

IEEE Journal on Selected Areas in Communications

Due to the explosive growth in the number of wireless devices and diverse\nwireless services, such as virtual/augmented reality and\nInternet-of-Everything, next generation wireless networks face unprecedented\nchallenges caused by heterogeneous data traffic, massive connectivity, and\nultra-high bandwidth efficiency and ultra-low latency requirements. To address\nthese challenges, advanced multiple access schemes are expected to be\ndeveloped, namely next generation multiple access (NGMA), which are capable of\nsupporting massive numbers of users in a more resource- and\ncomplexity-efficient manner than existing multiple access schemes. As the\nresearch on NGMA is in a very early stage, in this paper, we explore the\nevolution of NGMA with a particular focus on non-orthogonal multiple access\n(NOMA), i.e., the transition from NOMA to NGMA. In particular, we first review\nthe fundamental capacity limits of NOMA, elaborate on the new requirements for\nNGMA, and discuss several possible candidate techniques. Moreover, given the\nhigh compatibility and flexibility of NOMA, we provide an overview of current\nresearch efforts on multi-antenna techniques for NOMA, promising future\napplication scenarios of NOMA, and the interplay between NOMA and other\nemerging physical layer techniques. Furthermore, we discuss advanced\nmathematical tools for facilitating the design of NOMA communication systems,\nincluding conventional optimization approaches and new machine learning\ntechniques. Next, we propose a unified framework for NGMA based on multiple\nantennas and NOMA, where both downlink and uplink transmissions are considered,\nthus setting the foundation for this emerging research area. Finally, several\npractical implementation challenges for NGMA are highlighted as motivation for\nfuture work.\n

Evolution of NOMA Toward Next Generation Multiple Access (NGMA) for 6G