A new modified Gaussian approximation detector for space-time bit-interleaved coded modulation schemes

To reduce the receiver complexity of the space-time bit-interleaved coded modulation(ST-BICM) scheme, this letter describes a turbo-type iterative structure consisting of a modified Gaussian approximation(MGA) detector and an a posteriori probability (APP) decoder. Utilizing the characteristics of the interleaving and the central limited theoretic, the MGA detector first assumes the superposition of the transmitted signals as a Gaussian random variable. Then, P most significant signal combinations are identified to calculate the log-likelihood ratio of each bit. Without any pre-process on the received signals, the proposed method is free of matrix inverse operation and can be applied in systems with more transmit antennas than receive antennas. Furthermore, the performance of the MGA approaches that of the optimal detection.