Reducing the Mutual Outage Probability of Cooperative Non-Orthogonal Multiple Access

TL;DR

This paper introduces a novel power allocation scheme for cooperative NOMA that significantly reduces mutual outage probability and enhances reliability, achieving higher transmission rates and full diversity for users.

Contribution

A new power allocation method for CO-NOMA that improves reliability, derives a closed-form MOP expression, and demonstrates substantial performance gains over conventional schemes.

Findings

Lower mutual outage probability with the proposed scheme

Approximately 30% higher transmission rate at 15 dB

Full diversity achieved by each user

Abstract

In this letter, a new power allocation scheme is proposed to improve the reliability of cooperative non-orthogonal multiple access (CO-NOMA). The strong user is allocated the maximum power, whereas the weak user is allocated the minimum power. This power allocation alters the decoding sequence along with the signal-to-interference plus noise ratio (SINR), at the users. The weak user benefits from receiving multiple copies of the signal whereas the strong user benefits from the higher power allocation. Numerical simulation results show that the proposed scheme has a lower mutual outage probability (MOP) and offers better reliability as compared to the conventional power allocation scheme for CONOMA. An exact closed-form expression of MOP is derived for the two-user CO-NOMA system and it is shown that each user achieves full diversity. The proposed allocation is able to achieve approximately 30% higher transmission rate at 15 dB as compared to conventional CO-NOMA in a practical non-power balanced scenario.