MIMO MAP equalization and turbo decoding in interleaved space-time coded systems

Decoding of space-time codes in frequency-selective fading channels is considered. The approach is based on iterative soft-in soft-out equalization and decoding. It is applicable to space-time coded systems that deploy symbol/bit interleavers. We focus on the equalization stage by extending the Ungerboeck equalizer formulation to a multiple-input multiple-output time-variant channel. The resulting structure comprises a bank of matched filters, followed by an a posteriori probabilities calculator that runs the Bahl-Cocke-Jelinek-Raviv/maximum a posteriori algorithm with an appropriate metric. Simulation results are reported for space-time bit-interleaved codes designed over the enhanced data rates for GSM evolution (EDGE) air interface.