Performance of a turbo-coded CDMA system in a mobile satellite channel

The bit error rate (BER) performance of a turbo-coded code-division multiple-access (CDMA) system operating in a satellite channel is analysed and simulated. The system performance is compared for various constituent decoders, including maximum a posteriori probability (MAP) and Max-Log-MAP algorithms, and the soft-output Viterbi algorithm. The simulation results indicate that the Max-Log-MAP algorithm is the most promising among these three algorithms in overall terms of performance and complexity. It is also shown that, for fixed code rate, the BER performance is improved substantially by increasing the number of iterations in the turbo decoder, or by increasing the interleaver length in the turbo encoder. The results in this paper are of interest in CDMA-based satellite communications applications. Copyright (c) 2005 John Wiley & Sons, Ltd.