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International Symposium on Information Theory and its Applications

Unequal error protection QC-LDPC codes via Masking

Chi‐Jen Wu, Chung-Hsuan Wang, Chi-chao Chao

Published Dec 1, 2012• 1 citation
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Abstract

In this paper, a generalized construction of quasi-cyclic low-density parity-check (QC-LDPC) codes for unequal error protection (UEP) is proposed based on the masking technique. We can obtain UEP QC-LDPC codes as long as the Tanner graph of the masking matrix satisfies a general condition which can include our previous UEP construction as a special case. A sufficient condition to have flexible choice of protection levels is then presented. Simulation results show that the constructed codes can indeed provide codeword bits with different bit-error-rate performance.

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Globecom•Jan 1, 2004•3 citations
In this paper, a generalized construction of quasi-cyclic low-density parity-check (QC-LDPC) codes for unequal error protection (UEP) is proposed based on the masking technique. We can obtain UEP QC-LDPC codes as long as the Tanner graph of the masking matrix satisfies a general condition which can include our previous UEP construction as a special case. A sufficient condition to have flexible choice of protection levels is then presented. Simulation results show that the constructed codes can indeed provide codeword bits with different bit-error-rate performance.
In this paper, the algebraic constructions of quasi-cyclic low-density parity-check (QC-LDPC) codes with the unequal error protection (UEP) property are considered. A criterion for constructing such codes via the masking technique is proposed, based on which explicit conditions on the base parity-check matrices and masking matrices to achieve UEP are provided. We also give three specific constructions of UEP QC-LDPC codes. Furthermore, a sufficient condition to ensure strict UEP is presented. Simulation results demonstrate the superiority of our constructed codes over time-sharing schemes. The constructed codes also have competitive error performance against randomly constructed equal-error-protection LDPC codes and irregular UEP LDPC codes designed based on the degree distribution.
In this paper, a new construction of quasi-cyclic low-density parity-check (QC-LDPC) codes for unequal error protection (UEP) is proposed. We first give a new class of UEP block codes. QC-LDPC codes with binomial-term parity-check matrices which can avoid girths less than 8 and achieve an enlarged upper bound on the minimum distance are also introduced. An effective UEP scheme based on the proposed UEP block codes and QC-LDPC codes which can provide flexible choice of protection levels is then presented. Simulation results show that the new QC-LDPC codes can achieve good performance and low error floors. The bits with different designed protection levels can indeed have unequal bit-error-rate performance.
This paper presents a novel method for constructing high performance unequal error protection (UEP) quasicyclic low-density parity-check (QC-LDPC) codes. These codes are highly efficient and designed with flexible rates, lengths and number of protection levels. The given QC-LDPC codes are based on the combinatorial design. Each circulant constituting the parity check matrix of the UEP code is determined from subsets with the distinct difference between elements. Simulation results indicate that proposed UEP codes have equivalent performance to UEP codes constructed with the higher girth and lower rate, while achieving superior performance than the codes constructed by conventional equal error protection (EEP) techniques.
Algebraic constructions of quasi-cyclic (QC) low-density parity-check (LDPC) codes with unequal error protection (UEP) capabilities have recently been proposed, which can provide different error-correcting capabilities for different parts of the coded bits. However, conventional decoding algorithms are not designed for LDPC codes with UEP. In this paper, we propose three decoding schemes for UEP QC-LDPC codes extended from existing scheduling strategies, tailored to the special structures of the parity-check matrices. Simulation results show that the proposed schemes can provide improved error rate performance especially for coded bits on low protection levels. The decoding convergence can also be accelerated, thereby reducing the computational complexity.
A family of unequal error-protection (UEP) low-density parity-check (LDPC) codes, based on Plotkin-type constructions, is introduced. The codes are decoded in multiple stages in such a manner that the order of decoding determines the level of error protection. The level of UEP among the code bits can be further increased by properly combining structured and random-like LDPC component codes with carefully chosen properties, and by using some new reliability features. The proposed scheme also offers a good trade-off between code performance on the one hand and encoding/decoding and storage complexity on the other. To the best of our knowledge, the proposed approach represents the first iterative UEP method with analytically provable properties.