A New Rate Splitting Strategy for Uplink CR-NOMA Systems

TL;DR

This paper introduces a novel rate splitting strategy for uplink CR-NOMA systems that enhances secondary user outage performance without harming primary users, outperforming existing schemes.

Contribution

A new adaptive rate splitting method for uplink CR-NOMA that maximizes secondary user rates while maintaining primary user outage constraints.

Findings

Achieves the best secondary user outage performance among compared schemes.

Provides a closed-form expression for secondary user outage probability.

Enhances power efficiency through adaptive RS and SIC based on interference and channel gain.

Abstract

In uplink non-orthogonal multiple access (NOMA) channels, the existing cooperative successive interference cancellation (SIC) and power control (PC) schemes lack the capability of achieving the full capacity region, which restricts the outage performance of uplink NOMA users. For the uplink cognitive radio inspired NOMA system, we propose a new rate splitting (RS) strategy to maximize the achievable rate of the secondary user without deteriorating the primary user's outage performance. Based on the interference threshold and its own channel gain, the secondary user adaptively conducts RS, transmit power allocation and SIC, which utilizes the transmit power efficiently. The closed-form expression for the outage probability is derived for the secondary user. Numerical results show that the proposed RS scheme achieves the best outage performance for the secondary user among the existing cooperative SIC and PC schemes.