  In this paper a new message passing algorithm, which takes advantage of both
tree-based re-parameterization and the knowledge of short cycles, is introduced
for the purpose of decoding LDPC codes with short block lengths. The proposed
algorithm is called variable factor appearance probability belief propagation
(VFAP-BP) algorithm and is suitable for wireless communications applications,
where both good decoding performance and low-latency are expected. Our
simulation results show that the VFAP-BP algorithm outperforms the standard BP
algorithm and requires a significantly smaller number of iterations than
existing algorithms when decoding both regular and irregular LDPC codes.
