Newly developed Quasi-Cyclic low density parity check codes for hard disks record data

This paper presents a new technique for constructing the Quasi-Cyclic low density parity check (QC-LDPC) codes based on row division method. The new codes offer more flexibility in term of girth, code rates and codeword length. In this method of code construction, the rows are used to form as the distance graph. Then they are transformed to a parity-check matrix in order to acquire the desired girth. Simulation results show that the proposed QC-LDPC codes achieve a 0.1dB coding gain over randomly constructed codes and perform 1.3 dB from the Shannon-limit at a BER of 10^-6 with a code rate of 0.89 for block length of 1332.