Modified decoding algorithm for LDPC codes in MIMO-OFDM system

To reduce the complexity and improve performance of decoding algorithm for LDPC(low density parity check)codes,a modified min-sum algorithm is proposed to make up the performance drawback of traditional min-sum algorithm.Based on minimum mean square error rule,the modified min-sum algorithm makes full use of advantages of normalized decoding algorithm and offset decoding algorithm to approach to belief propagation decoding algorithm.The modified min-sum algorithm is applied in MIMO-OFDM(multiple input multiple output-orthogonal frequency division multiplexing) system to reduce intercarrier interference.Simulation results show that when MIMO-OFDM system asks BER(bit error ratio) to be 10-5,the encoding gain of modified min-sum decoding algorithm can be 0.5 dB better than traditional min-sum decoding algorithm,0.3 and 0.2 dB better than normalized decoding algorithm and offset decoding algorithm respectively,and only 0.15 dB worse than belief propagation decoding algorithm.In addition,the modified min-sum algorithm has low hardware complexity.