Transmit Strategies for Full-Duplex Point-to-Point Systems with Residual Self-Interference

In this paper, we study transmit strategies for a fullduplex (FD) point-to-point system with residual self-interference. Under the MISO and MIMO setup, finding optimal transmit strategies which maximize the system sum rate is a non-convex problem and in general NP-hard. Thus, we resort to a suboptimal solution which maximizes the signal-to-leakage-plus-noise ratio (SLNR). The SLNR based precoding design avoids the joint design of the precoders at the two transmitters. It also provides a closed-form solution. Noticing that properly adjusting the transmit power can also improve the performance of a FD system. We develop power adjustment schemes which maximize the system sum rate for SISO, MISO, and MIMO scenarios. The optimization problem is still non-convex. Nevertheless, by analyzing whether the constraints are active at the optimality, we are able to obtain a closed-form solution at the end. Due to the fact that the sum rate achievable power adjustment algorithms might violate the quality of service (QoS) requirements in the system, we also propose power adjustment schemes which consider the max-min fairness. Simulation results demonstrate that for our FD system the proposed schemes achieve a significant gain over traditional transmit strategies for half-duplex (HD) systems when they are applied to FD systems.