a system employs space - time coding characterized at the transmitter by bit - interleaved coded modulation combined with modulating several streams of the bicm encoded data for transmission over two or more antennas . space - time coding techniques improve transmission efficiency in radio channels by using multiple transmit and / or receive antennas and coordination of the signaling over these antennas . bit - interleaved coded modulation provides good diversity gain with higher - order modulation schemes that employ binary convolutional codes . a receiver demodulates the received signals and applies multi - input , multi - output demapping to estimate the bicm encoded bitstream . after deinterleaving of the bicm encoded bitstream , maximum a posteriori decoding is applied to the resulting bit stream to generate soft output values . by applying well - known turbo - decoding principles to iteratively demap and decode , the overall receiver performance is significantly improved . the mimo demapping and map decoding processes exchange likelihood information to improve the bit error rate performance over several iterations of demapping / decoding . by generating tentative decisions for transmitted bits , the overall number of evaluations used for demapping may be reduced .