Log-likelihood ratio calculation for iterative decoding on rayleigh fading channels using padé approximation

Gou Hosoya*, Hiroyuki Yashima

*この研究の対応する著者

研究成果: Article査読

抄録

Approximate calculation of channel log-likelihood ratio (LLR) for wireless channels using Padé approximation is presented. LLR is used as an input of iterative decoding for powerful error-correcting codes such as low-density parity-check (LDPC) codes or turbo codes. Due to the lack of knowledge of the channel state information of a wireless fading channel, such as uncorrelated fiat Rayleigh fading channels, calculations of exact LLR for these channels are quite complicated for a practical implementation. The previous work, an LLR calculation using the Taylor approximation, quickly becomes inaccurate as the channel output leaves some derivative point. This becomes a big problem when higher order modulation scheme is employed. To overcome this problem, a new LLR approximation using Padé approximation, which expresses the original function by a rational form of two polynomials with the same total number of coefficients of the Taylor series and can accelerate the Taylor approximation, is devised. By applying the proposed approximation to the iterative decoding and the LDPC codes with some modulation schemes, we show the effectiveness of the proposed methods by simulation results and analysis based on the density evolution.

本文言語English
論文番号970126
ジャーナルJournal of Applied Mathematics
2013
DOI
出版ステータスPublished - 2013
外部発表はい

ASJC Scopus subject areas

  • 応用数学

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