QoS-Based Linear Transceiver Optimization for Full-Duplex Multiuser Communications

In this paper, we consider a multiuser wireless system with one full duplex (FD) base station (BS) serving a set of half duplex (HD) mobile users. To cope with the in-band self-interference (SI) and co-channel interference, we formulate a quality-of-service (QoS) based linear transceiver design problem. The problem jointly optimizes the downlink (DL) and uplink (UL) beamforming vectors of the BS and the transmission powers of UL users so as to provide both the DL and UL users with guaranteed signal-to-interference-plus-noise ratio performance, using a minimum UL and DL transmission sum power. The considered system model not only takes into account noise caused by nonideal RF circuits, analog/digital SI cancellation but also constrains the average signal power at the input of the analog-to-digital converter (ADC) for avoiding signal distortion due to finite ADC precision. The formulated design problem is not convex and challenging to solve in general. We first show that for a special case with a worst case SI channel estimation error, the QoS-based linear transceiver design problem is globally solvable by a polynomial time bisection algorithm. For the general case, we propose a suboptimal algorithm based on alternating optimization (AO). The AO algorithm is guaranteed to converge to a Karush-Kuhn-Tucker solution. To improve the computational efficiency of the AO algorithm, we further develop a fixed-point method by extending the classical uplink-downlink duality in HD systems to the FD system. Simulation results are presented to demonstrate the performance of the proposed algorithms and the comparison with HD systems.