Frameworks of Non‐Orthogonal Multiple Access Techniques in Cognitive Radio Networks

The next‐generation communication systems demand huge spectral and energy efficiency, low latency, high scalability, improved connectivity and reliability, as well as advanced security due to massive growth in the wireless connected devices such as internet‐of‐things, wireless sensor networks, wireless body area networks, etc. The prominent and effective approaches to fulfill these demands are the cognitive radio (CR), non‐orthogonal multiple access (NOMA), multi‐antennas or multiple‐input‐multiple‐output, cooperative communication, network function virtualization, millimeter‐wave communication, ultra‐classification, etc. This chapter proposes the potential CR‐NOMA frameworks with the implementation challenges and future research directions. It presents the spectrum accessing strategies in CR. The chapter comprises the fundamentals of NOMA. The chapter also presents the prominent frameworks of NOMA in CR for uplink and downlink scenarios. It also comprises the challenging issues in CR‐NOMA frameworks and their recommended solutions.