New Designs of Robust Uplink NOMA in Cognitive Radio Inspired Communications

TL;DR

This paper introduces two innovative NOMA schemes for cognitive radio uplink communications that enhance secondary user performance without harming primary user reliability, ensuring robustness and avoiding outage probability floors.

Contribution

The paper proposes hybrid and fixed SIC-based NOMA schemes with power adaptation, improving secondary user service and transmission robustness in cognitive radio uplink scenarios.

Findings

Secondary users are served opportunistically without primary user degradation

Outage probability error floors are eliminated for secondary users

Proposed schemes outperform existing methods in simulations

Abstract

This paper considers a cognitive radio inspired uplink communication scenario, where one primary user is allocated with one dedicated resource block, while $M$ secondary users compete with each other to opportunistically access the primary user's channel. Two new designs of NOMA schemes, namely hybrid successive interference cancellation with power adaptation (HSIC-PA) and fixed successive interference cancellation with power adaptation (FSIC-PA), are proposed. The significant advantages of the proposed schemes are two folds. First, the proposed two schemes can ensure that the secondary users are opportunistically served without degrading the transmission reliability of the primary user. Besides, the transmission robustness of the served secondary users can be guaranteed. Specifically, the outage probability error floors can be avoided for the secondary users, which is proved by asymptotic analysis in the paper. Extensive simulation results are also provided to demonstrate the superior performance of the proposed schemes.