An analysis into the loopy belief propagation algorithm over short cycles

We investigate into the loopy belief propagation algorithm for binary low density parity check (LDPC) codes having cycles of small girth. Independence assumption among messages passed, assumed reasonable in all configurations of graphs, fails the most in graphical structures with short cycles. We investigate into this limitation and propose a modified algorithm, by considering dependency in the probability domain. This improves the performance of decoding over such graphs when compared to the original message passing algorithm at higher signal-to-noise ratio (SNR), thereby, yielding lower error floors.