Effects of the SNR Mismatch on Decoding the LDPC Codes

ZHANG Zhongming,XU Ba,YANG Jun,ZHANG Eryang

doi:10.3969/j.issn.1007130X.2011.

Computer Engineering & Science >

2011 , Vol. 33 >Issue 3: 167 - 171

DOI: https://doi.org/10.3969/j.issn.1007130X.2011.

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Effects of the SNR Mismatch on Decoding the LDPC Codes

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(School of Electronics Science and Engineering,National University of Defense Technology,Changsha 410073,China)

Received date: 2009-01-05

Revised date: 2009-10-21

Online published: 2011-03-25

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Abstract

The decoding of the LDPC codes by the belief propagation (BP) algorithm for the additive white Gaussian noise (AWGN) channel requires an accurate estimation of the signaltonoise ratio (SNR) for the computation of the a posteriori probabilities (APPs) of the received bits that serve as the decoder inputs. An erroneous estimation of SNR at the decoder is referred to as SNR mismatch. In this paper, we study the effects of the SNR mismatch on the bit error rate (BER) performance of the LDPC codes for the AWGN channel. The correctfactor function is achieved by approximating the check node update equation of the BP algorithm. It is concluded that the effect of SNR underestimation on decoding is more sensitive than SNR overestimation based on the correctfactor function. The simulation results also indicate the conclsion.

Key words： LDPC codes;belief propagation algorithm;SNR mismatch

Cite this article

ZHANG Zhongming,XU Ba,YANG Jun,ZHANG Eryang . Effects of the SNR Mismatch on Decoding the LDPC Codes[J]. Computer Engineering & Science, 2011 , 33(3) : 167 -171 . DOI: 10.3969/j.issn.1007130X.2011.

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