Construction of Quasi-Cyclic Low Density Parity Check Codes for Magnetic Induction Communication

The magnetic induction (MI) communication has been proved to be an effective method in the wireless underground sensor networks (WUSN). MI communication system based on quasi-cyclic low density parity check (QC-LDPC) codes is expected to improve the transmission performance in WUSN for its good performance and hardware friendliness. In this paper, we aim to construct an optimized QC-LDPC code with low encoding complexity for MI communication system. Firstly, we present a novel method, magnetic induction - protograph extrinsic information transfer (MI-PEXIT) algorithm, which can evaluate the performance of the QC-LDPC codes and predict the distance threshold for successfully transmission of the direct MI communication. Then, we combine the discrete particle swarm optimization (PSO) algorithm with the MI-PEXIT algorithm, and propose a novel scheme DPMIP method to optimize the QC-LDPC codes for MI communication system. Furthermore, two groups of QC-LDPC codes with low encoding complexity are constructed by the proposed DPMIP algorithm, which have different code parameters and different coil parameters. Simulation results validate the superiority of the proposed QC-LDPC codes for MI communication in WUSN, and the proposed codes also can achieve a good trade-off between the complexity and the performance.