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Performance of Low-Density Parity Check Codes With Parity Encoded by (1, 7) Run-Length Limited Code for Perpendicular Magnetic Recording

Maximum transition run (MTR) codes have recently been applied for perpendicular magnetic recording because of their high code rate. At the same time, the (1, 7) run-length limited (RLL) code, which increases the minimum distance of data transition, has not been applied due to a code rate that is lower than MTR codes. Therefore, in order to receive the advantages of both codes when low-density parity check (LDPC) codes are applied, this paper proposes an LDPC coding scheme with parity encoded by (1, 7) RLL code. This will increase the performance of LDPC codes and minimize the loss of code rate with MTR-coded user data in the perpendicular magnetic recording channel. The Viterbi trellis is easily modified by different constraints of MTR and (1, 7) RLL codes. Simulation results show that MTR-coded user data with (1, 7) RLL-coded LDPC parity performs approximately 0.3 dB better than MTR-coded user data with parity. It also performs better regardless of various user bit densities.