In this paper, we study the performance of Binary phase shift keying (BPSK) and Quartenary phase shift keying (QPSK) modulation signalling over fast and frequency non-selective Rayleigh fading channel with mobile digital communication and usually a decision feedback equalizer (DFE) at the receiver. Mobile communication is generally a complex process in which the input modulated signals propagate to the receiver over many different paths resulting in what is known as multipath propagation. Its main effects are delay spread and Doppler spread. These effects result in the channel being classified as fast and frequency non selective. Performances in terms of Bit Error Rate (BER) with respect to the Signal-to-Noise Ratio (SNR) at different selected velocities of 10, 40, 70 and 100km/hr are investigated with Adaptive Equalizer. Simulation results are obtained using MATLAB 7.0 programming language. The results indicate that at all the velocities considered; there is an excessive degradation in the BER performance due to fading with both the BPSK and QPSK modulation schemes. However, the BER improves for BPSK modulation signalling scheme when a decision feedback equalizer is used at the receiver
