Hybrid Nonorthogonal Multiple Access with Half and Full Duplex Cooperative Users

Abstract

In order to achieve high spectral efficiency, considerable attention has been paid to full-duplex (FD) and non-orthogonal multiple access (NOMA) technologies in the past decades. When FD users and half-duplex (HD) users access to the base station simultaneously, however, the rate region is still unknown. In this paper, we investigate hybrid NOMA (H-NOMA) systems, where a multi-antenna FD base station serves both a FD user and a HD uplink user over the same frequency band. The base station adopts successive interference cancellation (SIC) to decode the uplink signals, while the FD user is capable of adopting SIC to decode and cancel the inter-user interference. Given fixed transmission power, the achievable rate region of the H-NOMA system is the convex hull of the union of the rate regions of two alternative schemes with and without SIC at the FD user. Specifically, we derive the explicit expression of the rate region and demonstrate the potential of the proposed switching methods via numerical results.