Comparison of trellis coding and low rate convolutional coding for CDMA

Code division multiple access (CDMA) based on direct-sequence spread-spectrum (DS/SS) techniques is currently a subject of much research in the wireless communications field. Because of multiple access interference, CDMA systems require forward error correction for adequate performance. In this paper we compare two recently proposed channel coding techniques for CDMA systems, which hold the potential for improved CDMA performance, The first technique is low rate convolutional codes and the other technique is trellis codes which combine coding, modulation and spreading operations into a single step. Simulated performance for the codes is tested using two channel models: additive white gaussian noise (AWGN) channels and two-ray channels