Construction of Large Girth (3,k) LDPC Codes Based on Cuboid

The girth and minimum distance are two important factors of LDPC codes. In this paper we construct a type of LDPC codes with girth 8 based on cuboid. The codes are regular, whose column weight is 3. The minimum distance of the code with exact cuboid structure is only 8 and the distribution of code word weight is not optimal, so we proposed a scheme to improve the codes. The simulation results comparing the bit error rate (BER) performance over AWGN channels with randomly constructed LDPC codes shows that our codes are better than the randomly constructed ones