A Non-Orthogonal Multiple Access based Relaying Scheme for Cellular Two-Way Relay Networks

Abstract

In this paper, we propose a novel relaying scheme for cellular two-way relay networks (cWTRNs) based on non-orthogonal multiple access (NOMA) principle. Specifically, in the multiple access phase, signal space alignment based precoding is adopted at the base station such that the multiuser channels are divided into multiple sub-channels. In each sub-channel, NOMA is used to support two data streams. At the relay station, successive interference cancellation is employed for decoding, and XOR based network coding is used for signal forwarding. We analyze the achievable rate of the proposed NOMA based relaying scheme and investigate the power allocations to maximize the achievable sum-rate. Numerical results are presented and it is shown that the proposed scheme outperforms conventional amplify-and-forward based relaying scheme.