Performance Evaluation of Non-orthogonal Multiple Access in V2V communications Over Double-Rayleigh Fading Channels

In this paper, we investigate the performance of a downlink power-domain non-orthogonal multiple access (NOMA) system, wherein a base station (BS)/access point (AP) intends to communicate with the two users (i.e., UE1 and UE2) simultaneously in the same frequency band. Such concurrent transmission is made feasible by exploiting the power-domain approach, in which the near user is allocated less power while the far user is allocated relatively more power. By considering the BS/AP, UE1, and UE2 as moving vehicles, we model the vehicle-to-vehicle (V2V) channels between BS/AP and UE1 and between BS/AP and UE2 as double-Rayleigh fading. Under such channel modeling, we evaluate the individual outage probability of the users, overall outage probability, and system throughput expressions of the considered system. We verify our analytical and theoretical studies with the help of simulations. A comparison between our considered system and conventional orthogonal multiple access (OMA) system in terms of system throughput is also presented in this paper.