Research on residual self-interference real-time cancellation technology in in-band full duplex underwater acoustic communication system

In-band full duplex underwater acoustic communication (IBFD-UWAC) has become a major research topic in the field of underwater acoustic communication because its spectrum utilization can be twice as high as that of conventional half-duplex mode. The self-interference cancellation (SIC) technique is a core issue in IBFD-UWAC because the local emission of strong power self-interference signals can cause the BER performance of the communication system to fail to meet the normal requirements. To address the problem of residual interference signal (RIS) after simulated SIC or spatial self-interference suppression, hardware in-loop (HIL) simulation is used to implement real-time SIC based on Simulink^® Desktop Real-time platform, the instantaneous state error is used to determine the arrival of the desired signal, and an ISVSLMS algorithm with minimum variable step based on the desired signal arrival threshold is proposed in this paper. This algorithm greatly reduces the impact of the expected signal on the SIC process. Results of analyses, simulations and experiments show that this method can realize SIC for IBFD-UWAC in real time, and the convergence speed and steady-state effect of the algorithm are significantly improved.