Performance of convolutionally coded coherent DS-CDMA systems in multipath fading

Abstract

The performance of convolutionally coded DS-CDMA systems is analyzed assuming nonperiodic random spreading sequences, ideal interleaving and a RAKE receiver with perfect knowledge of the channel. In particular, a simple model for the memoryless coding channel that encompasses the effects of multiple access interference, self-noise and thermal noise is first derived. This coding channel model illustrates clearly how ideal channel state information is used at the receiver. Using new tight upper bounds on the bit error probability of convolutional codes over Nakagami, Rayleigh, and Rice fading multipath channels, the performance of convolutionally coded coherent DS-CDMA systems is then evaluated. Finally, the single-cell CDMA capacity is computed and the tradeoffs between performance and maximum number of simultaneous users in a cell are studied.