Iterative detection and decoding algorithms for block-fading channels using LDPC codes

We propose an Iterative Detection and Decoding (IDD) scheme with Low Density Parity Check (LDPC) codes for Multiple Input Multiple Output (MIMO) systems in block-fading receivers and fast fading Rayleigh channels. An IDD receiver with soft information processing that exploits the code structure and the behaviour of the log likelihood ratios (LLR)´s is developed. Minimum Mean Square Error (MMSE) receivers with Successive Interference Cancellation (SIC) and with Parallel Interference Cancellation (PIC) schemes are considered. The soft a posteriori output of the decoder in a block-fading channel with Root-Check LDPC codes has allowed us to create a new strategy to improve the Bit Error Rate (BER) of a MIMO IDD scheme. The proposed strategy has resulted in up to 3dB of gain in terms of BER for block-fading channels and up to 1dB in fast fading channels.