Untrusted NOMA with Imperfect SIC: Outage Performance Analysis and Optimization

TL;DR

This paper analyzes the outage performance of untrusted NOMA systems with imperfect SIC, deriving closed-form expressions for pair outage probability and optimizing power allocation to enhance reliability.

Contribution

It introduces a novel analysis of pair outage probability in untrusted NOMA with imperfect SIC and proposes an optimal power allocation scheme for improved reliability.

Findings

Closed-form POP expressions derived and validated

Optimal power allocation reduces outage probability

Benchmarking shows superiority over equal and fixed power schemes

Abstract

Non-orthogonal multiple access (NOMA) has come to the fore as a spectral-efficient technique for fifth-generation and beyond communication networks. We consider the downlink of a NOMA system with untrusted users. In order to consider a more realistic scenario, imperfect successive interference cancellation is assumed at the receivers during the decoding process. Since pair outage probability (POP) ensures a minimum rate guarantee to each user, it behaves as a measure of the quality of service for the pair of users. With the objective of designing a reliable communication protocol, we derive the closed-form expression of POP. Further, we find the optimal power allocation that minimizes the POP. Lastly, numerical results have been presented which validate the exactness of the analysis, and reveal the effect of various key parameters on achieved pair outage performance. In addition, we benchmark optimal power allocation against equal and fixed power allocations with respect to POP. The results indicate that optimal power allocation results in improved communication reliability.