# Performance Analysis of NOMA with Fixed Gain Relaying over Nakagami-m Fading Channels

## TL;DR

This paper analyzes the performance of NOMA with fixed gain relaying over Nakagami-m fading channels, deriving outage probabilities and diversity orders for two scenarios, showing NOMA's advantages over OMA in outage, throughput, and fairness.

## Contribution

It provides new closed-form expressions for outage probabilities and diversity orders for cooperative NOMA over Nakagami-m channels, comparing two relaying scenarios.

## Key findings

- NOMA outperforms OMA in outage probability and throughput.
- Diversity orders are μ(n+1) and μn for the two scenarios.
- Cooperative NOMA offers better outage performance than non-cooperative.

## 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 $n$-th user are $\mu(n+1)$ and $\mu n$, 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 to conventional OMA. By comparing the two scenarios, cooperative NOMA scenario can provide better outage performance relative to the second scenario.