Iterative detection for space-time coded synchronous CDMA communication systems

An iterative receiver is proposed for the downlink of CDMA communication systems that employ both a convolutional channel code and a space-time trellis code to achieve transmit diversity in the presence of channel fading. The proposed iterative receiver operates by exchanging extrinsic information between the channel and space-time decoders in each iteration. Comparison of performance results, obtained via simulations, with a similar system using Alamouti space-time codes (space-time block codes) shows that the proposed turbo decoder outperforms a concatenated system consisting of channel and Alamouti codes and that the performance gap increases with fast fading.