Comparative evaluation of the performance of anti-multipath modulation techniques for digital mobile radio systems

A comparative evaluation of the performance of Manchester coded PSK (MC-PSK), phase shift keying return to zero (PSK-RZ) and phase shift keying varied phase (PSK-VP) anti-multipath modulation techniques is presented. A two-ray propagation channel model using various delay spread values has been employed. The effect of spectral shaping of the transmitted signal on the BER performance of each of these modulation schemes, using Butterworth lowpass and square-root raised cosine premodulation filters, is investigated. The BER performance results obtained using these modulation techniques are compared with that of differential phase-shift keying (DPSK) modulation. It is shown that for a frequency non-selective fading channel, the performance of the anti-multipath modulation schemes is comparable to that of simple DPSK. However as the channel becomes frequency selective, the performance of the anti-multipath modulation systems improves beyond that provided by the DPSK system