Rate maximization for multi-code CDMA with optimized signatures

Joint transmitter/receiver optimization is studied for a direct-sequence (DS) code division multiple access (CDMA) system with multipath. Two optimization problems are considered corresponding to voice and data services, respectively: (i) minimizing the average transmitted power subject to a received signal-to-interference-plus-noise (SINR) constraint; (ii) maximizing the data rate subject to a transmitted power constraint. In the latter case, the rate is maximized by introducing multiple optimized spreading codes. Numerical results are presented which compare achievable rates with multi-code optimization vs. single-code optimization in the presence of fixed random interferers.