BER performance on multipath fading channels with random path delays

The bit error rate (BER) of trellis coded narrowband 8 PSK on multipath fading channels is found to depend strongly on the path delay differences, because these determine the number of resolvable paths. Assuming uniformly distributed path delays, the average BER is shown to decrease with increasing delay spread. The BER performance can be substantially improved by using spread-spectrum instead of narrowband signalling.