LDPC coded systems with D-BLAST structure

Abstract

Irregular low-density parity-check (LDPC) codes have shown exceptional performance for single-antenna systems over AWGN channels. In this paper, we investigate their application in multiple-input multiple-output (MIMO) systems over flat quasi-static Rayleigh fading channels. MIMO systems, with multiple antennas at both ends of the communication link, promise high capacity in theory [G.J. Foschini et al., March 1998], [E. Telatar, Nov. 1999], when the receiver has perfect knowledge of the channel state information. In order to exploit such high capacity with manageable receiver complexity, the Bell Labs layered space-time architecture (BLAST) and its variants have been proposed [(G.J. Foschini, Aug. 1996), (V. Tarokh et al., May 1999), (H.E. Gamal et al., Sept. 2001], which transmit independent bit streams on each layer (formed of selected transmit antennas for every time slot). In this paper, we study the diagonal BLAST structure with LDPC coding as the component code of each layer, employing iterative parallel MMSE (minimum mean square error) interference cancellation and detection [H.E. Gamal et al., Sept. 2001]. We show by simulation that LDPC codes can significantly outperform convolutional codes in the same layered structure, even for a very short frame containing 130 space-time symbols.