Abstract: In order to ensure the effective operation of in-band full-duplex communication system, aiming at the saturation problem of low noise amplifier and analog to digital conversion module in the system, combined with the nonlinear characteristics of power amplifier and the multipath effect of signal transmission, a two-stage self-interference elimination algorithm based on adaptive filtering algorithm is proposed. It is eliminated in analog domain and digital domain respectively. On this basis, a low complexity filter initial weight updating method is proposed to improve the recursive least squares algorithm to solve the problem that the traditional adaptive filter converges slowly when the channel changes. Simulation results show that the proposed algorithm can suppress the power of the self-interfering signal to the noise level, ensure the correct demodulation of useful signals, and effectively reduce the time required for the self-interfering signal elimination.

Key words: In-band full duplex communication, self-interference cancellation, adaptive filtering