An Optimal Unequal Error Protection LDPC Coded Recording System

For efficient modulation and error control coding, the deliberate flipping approach imposes the run-length-limited(RLL) constraint by bit error before recording. From the read side, a high coding rate limits the correcting capability of RLL bit error. In this paper, we study the low-density parity-check (LDPC) coding for RLL constrained recording system based on the Unequal Error Protection (UEP) coding scheme design. The UEP capability of irregular LDPC codes is used for recovering flipped bits. We provide an allocation technique to limit the occurrence of flipped bits on the bit with robust correction capability. In addition, we consider the signal labeling design to decrease the number of nearest neighbors to enhance the robust bit. We also apply the density evolution technique to the proposed system for evaluating the code performances. In addition, we utilize the EXIT characteristic to reveal the decoding behavior of the recommended code distribution. Finally, the optimization approach for the best distribution is proven by differential evolution for the proposed system.Comment: 20 pages, 18 figure

An Optimization Approach for an RLL-Constrained LDPC Coded Recording System Using Deliberate Flipping

For a recording system that has a run-length-limited (RLL) constraint, this approach imposes the hard error by flipping bits before recording. A high error coding rate limits the correcting capability of the RLL bit error. Since iterative decoding does not include the estimation technique, it has the potential capability of solving the hard error bits within several 7 iterations compared to an LDPC coded system. In this letter, we implement density evolution and the differential evolution approach to provide a performance evaluation of unequal error protection LDPC code to investigate the optimal LDPC code distribution for an RLL flipped system