Full-duplex OFDMA multi-user cellular systems: resource allocation and user pairing

In this paper, we consider an orthogonal frequency division multiple access multi-user cellular system with one full-duplex base station communicating with multiple half-duplex users in a bidirectional way. The uplink and downlink transmissions are coupled together because of the existence of the self-interference at the base station and the inter-user interference (IUI) from the uplink users to the downlink users. We aim to maximize the system sum-rate of uplink and downlink transmissions by optimally pairing the uplink and downlink users and allocating the subcarriers and powers to these users. We formulate the problem as a mixed integer nonlinear programming problem. A two-layer iterative solution based on the dual method and the sequential parametric convex approximation (SPCA) method is proposed. It is referred to as the dual-SPCA algorithm. The dual-SPCA algorithm requires the IUI channel state information to be available at the base station, and hence, a significant overhead is generated. To reduce the amount of overhead required, we assume that the IUI channel model is known at the base station, and we design a location-aware resource allocation algorithm with limited channel state information that maximizes the system sum-rate. Simulation results show that when self-interference is low, uplink and downlink user-pairing can provide significant improvement on the system sum-rate compared with the conventional unidirectional half-duplex transmission. In addition, by considering two different network deployments, such as urban macro cell scenario and small cell scenario, we show that the improvement of full-duplex transmission over half-duplex transmission highly depends on the channel parameters. Copyright (C) 2015 John Wiley & Sons, Ltd.