Combining-Based Spatial Domain SIC Method in a FD MIMO System by Addition of an RF Chain

In this paper, we propose and evaluate a spatial domain self-interference cancellation (SIC) method based on the principle of zero-forcing (ZF) beamforming for a generic multiple-input multiple-output (MIMO) full-duplex (FD) transceiver system in a large-scale communication scenario. The core of the proposed SIC method is to implement an additional radio-frequency (RF) chain at the receiver (RX) to induce an additional dimension on the channel matrix, so that the inversion of the channel matrix becomes feasible. To this end, we adapt, as an example, a simple ZF digital combiner in our system model to simultaneously perform SIC and enhance the communication link performance. Simulations results further confirm our proposal. In particular, our method demonstrates a strong SIC capability, even with an erroneous knowledge of the channel state information (CSI), and effectively improves the communication link performance of the FD system.