Performance of DS/SSMA systems with MTCM codes

We examine the use of multiple trellis coded modulation (MTCM) codes for a direct sequence spread spectrum multiple access (DS/SSMA) system for fading channels, and compare the results with Boudreau et al.'s (1990) system, in which the use of standard Ungerboeck type trellis codes in conjunction with a DS/SSMA system has been considered. A generalized transfer function method is used to evaluate upper bounds on bit error probability. Multiple access interference due to K asynchronous users transmitting simultaneously is computed using the method of moments. From the calculations and results, it is shown that DS/SSMA system with MTCM codes achieves better performance than the Boudreau et al.'s system.