A simple and efficient search method based on the coset concept is proposed to construct (3, ) quasi-cyclic low-density parity-check (QC-LDPC) codes without small cycles. Compared with the random search method, the chance to find large-girth codes is remarkably increased for the new method. Compared with Tanner's construction, the proposed method is much more flexible in the selection of row weight . Some new codes are constructed with the shortest lengths compared with those constructed by the existing well-known methods. Simulation results show that the novel codes with moderate length perform well in the additive white Gaussian noise channel.
NETL
NSTL
