Joint Full-Duplex and Roadside Unit Selection for NOMA-Enabled V2X Communications: Ergodic Rate Performance

Vehicle-to-everything (V2X) communications are regarded as the key technology in future vehicular networks. V2X features promising benefits in providing efficient and reliable massive connections, improving traffic efficiency and safety, as well as supporting in-vehicle entertainment and other functions. Recently, non-orthogonal multiple access (NOMA) is further known as a promising solution in the fifth-generation (5G) mobile communication systems. Such NOMA has drawn much attention because of its ability to significantly improve the network throughput and lower the accessing and transmission latency to meet the quality-of-service (QoS) requirements of many 5G-enabled applications. In this respect, this paper first considers a full-duplex (FD) transmission mode together with the Roadside Unit (RSU) selection scheme in a NOMA-V2X networks since relay selection based NOMA network is introduced as technique to increase the ergodic capacity. In the considered NOMA-V2X systems, the vehicles enable device-to-device (D2D) transmission mode to permit two nearby vehicles communicate at close distances. To further robust performance, the vehicle requires relaying transmission in group of RSUs which tight connected with a cellular network. Secondly, we compare ergodic rate performance of two vehicles in specific group. Finally, we evaluate the ergodic performance by deriving the exact and closed-form expressions of ergodic rate in various scenarios. The results show that ergodic rate improvement can be achieved by increasing the number of RSUs and limiting impact of self-interference due to the FD mode.