Adaptive Interference Cancellation System with Different Correlation Control Methods

This paper investigates the correlation-integrator, correlation-lowpass and correlation-proportion control methods of an adaptive interference cancellation system (AICS). For a single channel AICS, the convergence characteristic of different control methods is gained and contrasted. The different functions of using active lowpass and passive lowpass are analyzed. The formulation of the changes of interference cancellation ratio (ICR) and convergence time with the change of interference signal is calculated. Under the correlation-integrator control, the optimum weights can be gained and the residual error is zero. With the correlation-lowpass control and correlation-proportion control, the steady-state weights differ from the optimum weights, so the residual error is not zero. Active lowpass has more advantages for increasing ICR and convergence speed than passive lowpass. The more interference signal decreases, the lower ICR is for lowpass and proportion control and the longer time converging to steady-state will be for all the control methods. If we limit a convergence time as a standard, the ratio of the convergence time to the limiting time is a quadratic function of the reduce times of the interference signal.