Cooperative non-orthogonal multiple access with physical layer network coding

Abstract

Physical layer network coding (PNC) has been proposed for information exchange between a pair of users assisted by a relay. However, the spectral efficiency of PNC reduces when the number of user pairs increases due to the requirement of orthogonal channels for multi-pair operation. This paper proposes the use of cooperative non-orthogonal multiple access (NOMA) and PNC to improve the spectral efficiency and outage performance of multi-pair information exchange. Specifically, a cognitive radio inspired NOMA is considered. The quality of service of the primary user pair is guaranteed through dynamic power allocation policy, while the secondary user pair is served on best effort basis. The simulation result shows that the proposed cognitive radio inspired NOMA scheme with PNC achieves higher spectral efficiency and better outage performance if compared with the existing orthogonal multiple access schemes with PNC.