On Turbo Equalization of Interleaved Space-Time Codes

Space-time coding over frequency selective block fading channels is considered. The approach is based on deploying interleaved space-time codes. Decoding is based on the iterative concatenation of a soft-in soft-out equalizer with a soft-in soft-out decoder. Guidelines for the construction of interleaved space-time codes that exploit the spatial, temporal, and frequency diversities are given. The equalizer structure comprises a bank of matched filters followed by a maximum a posteriori processor with an appropriate metric. Although no multiple receive antennas are required, the complexity grows exponentially with the number of transmit antennas and modulation order. Therefore, methods for reducing complexity are devised. The performance is illustrated for several space-time schemes based on bit-interleaved convolutional codes.