Operating LDPC Codes with Zero Shaping Gap

Authors

G. Böcherer, R. Mathar,

Abstract

        Unequal transition probabilities between input and output symbols, input power constraints, or input symbols of
unequal durations can lead to non-uniform capacity achieving input distributions for communication channels. Using uniform input distributions reduces the achievable rate, which is called the shaping gap. Gallager’s idea for reliable communication with zero shaping gap is to do encoding, matching, and jointly decoding and dematching. In this work, a scheme is proposed that consists in matching, encoding, decoding, and dematching. Only matching is channel specific whereas coding is not. Thus off-the-shelf LDPC codes can be applied. Analytical formulas for shaping and coding gap of the proposed scheme are derived and it is shown that the shaping gap can be made zero. Numerical results show that the proposed scheme allows to operate off-the-shelf LDPC codes with zero shaping gap and a coding gap that is unchanged compared to uniform transmission.

BibTEX Reference Entry 

@inproceedings{BoMa11b,
	author = {Georg B{\"o}cherer and Rudolf Mathar},
	title = "Operating {LDPC} Codes with Zero Shaping Gap",
	pages = "330-334",
	booktitle = "{IEEE} ITW 2011",
	address = {Paraty, Brasil},
	month = Oct,
	year = 2011,
	hsb = hsb999910075522,
	}

Downloads

 Download paper  Download bibtex-file

This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights there in are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author's copyright. In most cases, these works may not be reposted without the explicit permission of the copyright holder.