Low-Complexity Check-Node-Based Serial Scheduling Belief Propagation for LDPC Codes

Compared to classic channel coding, Low-density parity-check (LDPC) codes have proved to be very powerful channel coding schemes with a broad range of applications. However, as maximum-likelihood decoding is too complex to implement, suboptimal decoders have to be employed .One of the most popular decoding algorithms of LDPC codes is belief propagation (BP) decoding. Informed Dynamic Scheduling (IDS) can provide a better BER performance, but hard to implement due to high computational complexity increased. In order to improve the convergence, a simple low-complexity sequential check-node-based scheduling strategy is proposed. A new check-node-based reliability measure is defined, which represents the degree of reliability approximately. The reliability measure is used for ordering while the actual message updates still use the exact BP equations. During an iteration , the schedule strategy finds an update sequence, which is arranged by the new defined reliability measure in ascending order. Complexity is compared among those algorithms. Mechanism why the new strategy works effective is presented. Simulation shows that the new approach significantly improve the BER performance using short-length block LDPC codes and reduce iterations.