Modified belief propagation decoding algorithm for low-density parity check code based on oscillation

Satoshi Gounai, Tomoaki Ohtsuki, Toshinobu Kaneko

研究成果: Conference contribution

16 被引用数 (Scopus)

抄録

A Low-Density Parity Check (LDPC) code with the Belief Propagation (BP) or the Log-Likelihood Ratio Belief Propagation (LLR-BP) can achieve good Bit Error Rate (BER) performance approaching the Shannon limit. When a parity check matrix of the LDPC code has the cycle, the BP and LLR-BP decoding algorithms achieve approximate Maximum A posterior Probability (MAP) decoding. Although the decoding algorithms are approximate MAP decoding, LDPC codes can achieve very good BER. For the short and middle length LDPC codes, BER and BLock Error Rate (BLER) performances are affected by cycle largely. In each iteration, the magnitudes of a posterior LLRs of some bits oscillate owing to cycles. The oscillation is the dominant error factor in the high Eb/N0 region for short and middle length LDPC codes. In this paper, we extend the definition of oscillation to extrinsic LLR (ex-LLR) derived in the bit node process and propose the modified LLR-BP and the modified UMP-BP decoding algorithms. To reduce effects of oscillating ex-LLRs on decoding, for oscillating ex-LLRs, we add the previous ex-LLR to the current ex-LLR. From the computer simulation, we show that for short and middle length LDPC codes, with a simple modification, our proposed decoding algorithms can improve the conventional LLR-BP and UMP-BP decoding algorithms. In particular, we show that the modified UMP-BP decoding algorithm with low complexity can achieve better BER and BLER than the conventional LLR-BP decoding algorithm.

本文言語English
ホスト出版物のタイトル2006 IEEE 63rd Vehicular Technology Conference, VTC 2006-Spring - Proceedings
ページ1467-1471
ページ数5
出版ステータスPublished - 2006 12 1
イベント2006 IEEE 63rd Vehicular Technology Conference, VTC 2006-Spring - Melbourne, Australia
継続期間: 2006 5 72006 7 10

出版物シリーズ

名前IEEE Vehicular Technology Conference
3
ISSN(印刷版)1550-2252

Other

Other2006 IEEE 63rd Vehicular Technology Conference, VTC 2006-Spring
CountryAustralia
CityMelbourne
Period06/5/706/7/10

ASJC Scopus subject areas

  • Computer Science Applications
  • Electrical and Electronic Engineering
  • Applied Mathematics

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