Time-frequency code for multicarrier DS-CDMA systems

A novel trellis coded modulation scheme for a multicarrier DS-CDMA system is studied in this paper. Based on the concept of transmission diversity in the time-frequency domain, we propose a code design criterion that includes diversity gain and coding gain. In terms of the proposed criterion, we can search for codes that have larger coding gain while keeping the maximum diversity. Results show that the bit error rate performance of the system with the novel trellis coded modulation is much better than that of the traditional system while not occupying additional spectral bandwidth.