带内全双工水声通信残余自干扰实时抵消技术研究

带内全双工水声通信(In-Band Full Duplex Underwater Acoustic Communication,IBFD-UWAC)因其频谱利用率可达传统半双工模式的两倍，已成为水声通信领域的研究热点之一。由于本地发射强功率自干扰信号会导致通信系统误码率性能无法达到正常需求，因此自干扰抵消(Self-interference Cancellation,SIC)技术成为IBFD-UWAC中的核心问题。针对经过模拟SIC或空间自干扰抑制后的残余干扰信号问题，文章利用硬件在环(Hardware In-Loop,HIL)仿真，基于Simulink^® Desktop Real-time平台，实现了实时SIC，并利用瞬时状态误差判断期望信号到达情况，提出一种基于期望信号到达阈值的改进Sigmoid函数可变步长最小均方(Improved Sigmoid function based Variable Step Size,LMS,ISVS-LMS)算法，该算法大大降低了期望信号对SIC过程带来的影响。分析、仿真及实验表明：该方法可实现实时带内全双工水声通信的自干扰抵消，且算法的收敛速度以及稳态效果均有显著提升。

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.