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High-Rate Maximum Runlength Constrained Coding Schemes Using Nibble Replacement

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Abstract

In this paper, we will present coding techniques for the character-constrained channel, where information is conveyed using q-bit characters (nibbles), and where w prescribed characters are disallowed. Using codes for the character-constrained channel, we present simple and systematic constructions of high-rate binary maximum runlength constrained codes. The new constructions have the virtue that large lookup tables for encoding and decoding are not required. We will compare the error propagation performance of codes based on the new construction with that of prior art codes.

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... To deal with the problem, several approaches using LDPC codes for the ECC scheme have addressed [5]- [10]. In [5], a user-data word was split into some portions, and then each portion was encoded by a constrained encoder and was formatted according to the LDPC structure so that combined ECC-constrained codewords satisfied both the ECC structure condition and the constrained code condition. ...
... In this study, we first design a configuration of k constrained codes with LDPC codes. The k constrained codes herein are constructed using a nibble replacement method [10], [11], which as reported recently could achieve high coderates, simple encoders and decoders, and limited the error propagation. Then, we also extend our research to design DCfree k constrained LDPC codes. ...
... The k constrained codes based on the nibble replacement have been reported recently in [10], [11]. Basically, the technique removes all inadmissible q-bit nibbles and replaces them by q-bit admissible ones, where the admissible nibbles are predefined, i.e., dec(u) ≥ w, where the function dec() refers to the decimal representation of a binary sequence u, and w is a predefined integer. ...
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