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Design techniques for weakly constrained codes

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Abstract

A general method of constructing run-length limited (d, k) constrained codes from arbitrary sequences is introduced. This method is then combined with the method of guided scrambling for constructing a class of weakly constrained codes. The proposed codes are analyzed for the case of d=0 and are shown to give results which are better or comparable to those of the best available codes, however, at the cost of failure with some very low probability. For d>0, the code efficiency of the codes constructed according to the proposed method reduces significantly.

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... We refer to such a simple, fixed-rate encoding as plain bit stuffing. This method has been adopted for the design of weakly-constrained codes in [22], where constraint violation is permitted with a small probability. However, the constraints considered in this work are not weak (no constraint violations permitted), and in such cases plain bit stuffing results in sizeable rate loss. ...
... In what follows, we outline a systematic procedure to build near-capacity, fixed-rate (0, k) codes based on the bit stuff algorithm. While using dummy bits similar to [22], we introduce an additional iterative pre-processing of the fixed-length input that is central to achieving high encoding rates. Essentially, the role of pre-processing is to better conform the input data to bit insertion. ...
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