Low-density parity-check (LDPC) coded MIMO systems with iterative turbo decoding

Transmit diversity schemes have been studied for high spectral-efficiency and high bit-rate transmission, such as multi-input multi-output (MIMO) systems. In the MIMO system, forward error correction coding is essential for high quality communications. Recently, low-density parity-check (LDPC) codes have attracted much attention as good error correcting codes like turbo codes. LDPC codes have been applied to MIMO systems, where we refer to the system as the MIMO-LDPC. In this paper, we propose a new MIMO-LDPC system with iterative turbo decoding (MIMO-LDPC-TD) using two LDPC encoders and two LDPC decoders to improve the performance of the MIMO-LDPC. Since each decoder in the MIMO-LDPC-TD is smaller than that in the MIMO-LDPC, the decoding complexity at each decoder in the MIMO-LDPC-TD is less than that in the MIMO-LDPC. We also compare the performance of the MIMO-LDPC with that of the turbo coded MIMO systems (MIMO-turbo) on flat Rayleigh fading channels. We show that the MIMO-LDPC-TD can achieve the good error rate performance with reduced decoding complexity at each decoder on it flat Rayleigh fading channel, particularly on a slow fading channel. We also show that the MIMO-LDPC can achieve the better error rate performance than the MIMO-turbo on a fast Rayleigh fading channel.