Investigation of Backscatter-Enabled Partial NOMA Systems: Outage Probability and Ergodic Capacity Evaluation

This paper proposes a novel backscatter-enabled partial non-orthogonal multiple access (part-NOMA) system design with imperfect successive interference cancellation. By exploiting part-NOMA combined with backscatter deployments, the considered system can flexibly control the overlap signal of two vehicles via either NOMA and orthogonal multiple access (OMA) to deal with the variation of channel conditions and their priorities while achieving spectral efficiency improvement and efficient interference reduction. On that basis, we first derive closed-form approximations for the outage probability of vehicles and then carry out the respective asymptotic in high signal-to-noise regions. This enables us to gain the diversity and coding gain of vehicles on the one hand and directly show how the considered system effectiveness compared to conventional NOMA and OMA counterparts by mathematical perspectives on the other hand. Moreover, we also provide guidance on how to achieve the approximate and asymptotic ergodic capacity in closed-form expressions, which is beneficial for pointing out the vehicles' ergodic slope and demonstrating the effectiveness of part-NOMA over classical NOMA. Finally, we provide some illustrative simulations to verify our developed theoretical analyses.