Performance of Turbo Codes in Asynchronous DS-CDMA Systems with Space-time Detection over Frequency-selective Fading Channels

W. Hamouda and P. McLane (Canada)


DS-CDMA, turbo coding, channel interleaving, frequency-selective fading.


The performance of minimum mean-squared error (MMSE) multiuser detection (MUD) using adaptive antenna array processing and turbo codes (TC) is analyzed for binary direct-sequence code-division multiple-access (DS-CDMA) systems over frequency-selective fading channels. In addition, we perform a comparison between turbo and convolutional codes where we find that the former significantly outperforms the latter at all practical bit-error-rate (BER) levels. In a fully interleaved fading channel where ideal channel interleaving is assumed, it is found that increasing the size of the encoder interleaver does not always led to a significant BER improvement. On the other hand in a correlated Rayleigh fading channel, where channel memory exists, it is shown that using a practical channel memory exists, it is shown that using a practical channel interleaver of depth equal to 30 is sufficient to bring system's performance very close to the ideal interleaving case. Finally, we show the use of antenna array processing has a great impact on the TC performance in the space-time system.

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