Performance Analysis of NOMA With Fixed Gain Relaying Over Nakagami- $m$ Fading Channels

TLDR

The study investigates cooperative NOMA with fixed‑gain amplify‑and‑forward relaying over Nakagami‑m fading channels, deriving closed‑form outage probability expressions to characterize performance. The authors analyze two scenarios—one with fixed‑gain AF relaying and existing direct links, and one without relaying—over Nakagami‑m fading channels. The results show that NOMA achieves diversity orders of μ(n+1) and μn in the two scenarios, outperforms OMA in outage probability and throughput, provides better fairness, and that cooperative relaying improves outage performance.

Abstract

This paper studies the application of cooperative techniques for non-orthogonal multiple access (NOMA). More particularly, the fixed gain amplify-and-forward (AF) relaying with NOMA is investigated over Nakagami-m fading channels. Two scenarios are considered insightfully: 1) the first scenario is that the base station (BS) intends to communicate with multiple users through the assistance of AF relaying, where the direct links are existent between the BS and users and 2) the second scenario is that the AF relaying is inexistent between the BS and users. To characterize the performance of the considered scenarios, new closed-form expressions for both exact and asymptomatic outage probabilities are derived. Based on the analytical results, the diversity orders achieved by the users are obtained. For the first and second scenarios, the diversity order for the nth user are μ(n + 1) and μn, respectively. Simulation results unveil that NOMA is capable of outperforming orthogonal multiple access (OMA) in terms of outage probability and system throughput. It is also worth noting that NOMA can provide better fairness compared with conventional OMA. By comparing the two scenarios, cooperative NOMA scenario can provide better outage performance relative to the second scenario.