Influence of fading channel prediction on the performance of QPSK system in the presence of PSK interference

In this paper we consider performance evaluation of QPSK transmission system operating in a frequency nonselective fading channel in the presence of PSK interference. A algorithm that combines decision feedback and adaptive linear prediction (DFALP) (Y. Liu et al. 1995) by using tentative coherent detection and the least mean square (LMS) algorithm is used for tracking the phase and amplitude of the fading channel. The channel gain is predicted by FIR and IIR filters employing LMS algorithm. Simulation results are given for the system´s performance using FIR and IIR filters. The special case of IIR filter having length of unity is well-known Kalman-LMS filter.