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

A full-diversity full-rate (FDFR) design was developed recently, to enable an uncoded layered space-time (LST) system 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. We investigate the performance of a coded FDFR system obtained by concatenating an error control coding (ECC) module and an FDFR module with a random interleaver in between. Iterative decoding is performed at the receiver. With R_c denoting the ECC rate, and d the minimum Hamming distance, an over-all transfer rate of R_cN_t symbols per channel use and a full diversity order dN_tN_r are achieved. Compared with coded V-BLAST, without sacrificing rate the coded FDFR system offers evident performance improvement when relatively weak codes are used. As N_r increases, even such a strong code as rate 1/2 turbo codes can benefit from FDFR. Specifically, 1.5 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 code is used. The price paid is increased complexity.