Optimized adaptive algorithm of digital self-interference cancellation based on improved variable step

Full-duplex wireless communication system transmits and receives signals in a same frequency band and at a same time, which solves the problem of the low using efficiency of limited radio spectrum resource, and doubles the channel capacity. However, it also brings a new problem that the full-duplex node will generate a strong self-interference signal. And to deal with the self-interference signal, using existing negative self-interference cancellation and analog self-interference cancellation technology are not enough, effective digital self-interference cancellation is needed for further cancellation. This paper proposes an optimized adaptive algorithm of digital self-interference cancellation based on improved variable step. By using a iteration threshold, we establish a new nonlinear relationship between the step factor and the error signal, which overcomes the slow change problem when the error signal is getting closed to zero, and accelerates the convergence rate.