BICM using LDGM codes and ML channel estimation for MIMO channels

Recently, a bit-interleaved coded modulation scheme based on iterative decoding (BICM-ID) for MIMO channels have been proposed. The method exhibits very low encoding and decoding complexities thanks to the use of a concatenated LDGM code as the channel encoder and a modified sphere detector for bit likelihood computation. Simulation results showed that it was possible to achieve a performance near the capacity limits over perfect-interleaved, fast fading Rayleigh channels with perfect channel state information (CSI) available at the reception. In this work we extend these results to the more practical situation where the fading is quasi-static and the channel is estimated at the receiver. The channel estimation method investigated in this work is based on the maximum likelihood principle and makes use of the expectation-maximization (EM) algorithm.