Improving the performance of coded FDFR multi-antenna systems with turbo-decoding

A full-diversity full-rate (FDFR) multi-antenna system was developed recently, enabling uncoded layered space-time (LST) transmissions to achieve full-diversity (N_tN_r) and full-rate (N_t symbols per channel use) simultaneously, for any number of transmit antennas N_t and receive antennas N_r. In this paper, we investigate the performance of a coded FDFR design obtained by concatenating an error control coding (ECC) module and FDFR module with a random interleaver in between. Turbo decoding is performed at the receiver. With R_c denoting the ECC rate, d_min the minimum Hamming distance of the ECC, and M the constellation size, an overall transfer rate of R_cN _tlog₂M bits per channel use and a full diversity order d_minN_tN_t are achieved. Different ECC choices are considered. Approximate analysis reveals that multi-stream ECC and single-stream ECC make no difference when cbnvolutional codes with long frame length and near-optimal MIMO decoding schemes are adopted. Without sacrificing rate, the coded FDFR system improves error performance compared with coded V-BLAST, when relatively weak codes are used. As N_r increases, even strong codes such as rate 1/2 turbo codes can benefit from FDFR. Specifically, 1.5-2 dB gain over coded V-BLAST is obtained in a 2 × 2 antenna setup when convolutional codes or rate 3/4 turbo codes are used; 0.5 dB gain is offered in a 2 × 5 setup when rate 1/2 turbo codes are used. Coded FDFR also outperforms a 16-QAM Alamouti coded scheme by 1 dB when convolutional codes are used. The price paid is increased complexity.