Phase Compensation Self-interference Cancellation Method for Full-duplex Single-Carrier Underwater Acoustic Communication

Aiming at the problem that the self-interference cancellation performance is degraded due to the phase mismatch between the transmitting and receiving samples in the in-band full-duplex underwater acoustic communication, this paper proposed a method to improve the self-interference cancellation through two-stage phase compensation in single-carrier communication. The traditional method assumes that the phase of the reference signal is consistent with the phase of the received signal and directly cancels under this premise. In contrast, this paper introduced phase compensation into the construction process of the reference signal and took the minimum residual energy as the optimization goal. This method first estimated the initial phase based on the correlation between the reference signal and the received signal and further searched in the field of this result to find the optimal compensation phase and achieve compensation. It combined the adaptive filtering algorithm to improve the self-interference cancellation ability. The effectiveness of the proposed method was verified by the simulation of single frequency signal and a quadrature phase shift keying signal, the pool experiments, and the sea experiments. The results show that after phase compensation, the self-interference cancellation performance of the system is improved; the self-interference cancellation performance in the pool experiment is improved by 5.289 dB, and the self-interference cancellation performance in the sea experiment is improved by 1.986 dB. After compensation, the main side lobe ratio of the correlation peak of the far-end signal demodulation is optimized. The phase compensation method proposed in this paper can effectively improve the self-interference cancellation performance and filter’s convergence speed, thereby improving the accuracy of system demodulation and providing key technical support for the practical application of full-duplex underwater acoustic communication.