Sum-Rate Maximization in Non-Orthogonal Multiple Access Relay Networks

Abstract

In this paper, we investigate the sum-rate maximization problem in a cooperative relay network, which employs non-orthogonal multiple access (NOMA). Specifically, we address the problem of optimal power allocation and relay precoder design. The corresponding optimization problem turns out to be non-convex. In order to get around the difficulty to deal with non-convexity, we propose a minorization-maximization technique based algorithm to jointly optimize source power allocation and relay precoder design. We then solve the problem to optimally allocate power at source and design the precoder at relay. For the case of two destination nodes, we propose a grid search based approach. Simulation results are provided to illustrate the performance of the proposed algorithm.