Outage Performance of CDRT-based Cognitive NOMA Intelligent Transportation Systems with Imperfect Successive Interference Cancellation

With the dramatic development of wireless communication technology, intelligent transportation systems (ITS) are facing the problems of low spectrum utilization and unprotected quality of service (QoS) for edge users in secondary networks. In addition, successive interference cancellation (SIC) is the key aspect of the NOMA technology and has a significant impact on system performance. Cognitive radio (CR), non-orthogonal multiple access (NOMA) and coordinated direct and relay transmission (CDRT) are proved to be effective techniques for solving these problems. This work investigates the performance of a CDRT-based overlay cognitive NOMA ITS. Imperfect SIC of the full duplex secondary base station (SBS) is considered separately. Subsequently the closed expression for the outage probability of each user is obtained. Finally, simulation verification is performed and compared with classical NOMA transmission, concluding that the outage probability of edge users in the proposed system is smaller under better SIC capability.