User Association and Resource Allocation in Full-Duplex Relay Aided NOMA Systems

To support ubiquitous connectivity and the rising demand of tele-traffic in the Internet of Things (IoT), we amalgamate nonorthogonal multiple access (NOMA) and full-duplex (FD) techniques to propose a new hybrid NOMA (FDH-NOMA) framework. We formulate an ergodic sum rate maximization problem under statistic channel state information (CSI). To simplify optimization, we derive upper and lower bounds to the ergodic sum rate and decompose the rate upper bound maximization problem into two subproblems, namely, user association and resource allocation. Since these two subproblems are coupled, we design an iterative algorithm for successively optimizing ergodic sum rate. In user association, we propose the mode selection criterion and NOMA mode pairing scheme, whereas for resource allocation, we optimize both interpair and intrapair resource allocation. Our numerical results demonstrate the strength and the effectiveness of our proposed FDH-NOMA framework and optimization algorithm.