Energy-efficient LDPC layered decoder

It is very important to reduce the energy consumption of low-density parity-check (LDPC) decoders, especially for the intelligent and mobile terminals in green communications. This paper presents a novel energy-efficient layered decoder (EELD) to save the power consumption of quasi-cyclic LDPC (QC-LDPC) decoders based on the layered belief propagation (LBP) algorithm. The EELD forces a check-node process into asleep, when all the reliabilities of its neighboring variable nodes exceed the lazy threshold. The EELD also adopts the lower limit of the beliefs, rather than all the beliefs, of the neighboring variable nodes to compare with the lazy threshold in order to decide the state of check-node process. The EELD can skip the useless check-node processes to save energy consumption with slight additional complexity. Simulation results show that the EELD can improve the power efficiencies of the decoders by up to 28% for WiMAX codes without loss of error performances.