Pseudo-ARQ for a Low Density Parity Check Code Decoder

A pseudo automatic repeat request scheme for a LDPC decoder is presented which dramatically improves the probability of an error in an information binary digit over the signal-to-noise ratio (SNR) range 0 dB to 2 dB, by sacrificing the information throughput, with the added advantage of not being adversely affected by a fluctuation in the channel SNR. A frame, which consists of the concatenation of several code words, is retransmitted only if the channel signal- to-noise ratio estimate is found to be lower than a set threshold. Overall, the throughput is only briefly reduced as required to ensure excellent performance over low and high SNRs. Simulation results are presented for rate 1/2 (288, 576) WiMAX 802.16e LDPC code over an A WON channel with binary phase shift keying (BPSK) modulation.