Reduced complexity iterative decoding of low-density parity check codes based on belief propagation

In this paper, two simplified versions of the belief propagation algorithm for fast iterative decoding of low-density parity check codes on the additive white Gaussian noise channel are proposed. Both versions are implemented with real additions only, which greatly simplifies the decoding complexity of belief propagation in which products of probabilities have to be computed. Also, these two algorithms do not require any knowledge about the channel characteristics. Both algorithms yield a good performance-complexity tradeoff and can be efficiently implemented in software as well as in hardware, with possibly quantized received values. Index Terms - APP decoding, belief propagation, block codes, four-density parity check codes, iterative decoding.