| Project/Area Number |
08650429
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
情報通信工学
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| Research Institution | NARA Institute of Science and Technology |
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Principal Investigator |
KASAMI Tadao Graduate School of Information Science, NARA Institute of Science and Technology, Prfoessor, 情報科学研究科, 教授 (50029378)
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| Co-Investigator(Kenkyū-buntansha) |
FUJIWARA Toru Department of Information and Computer Science, Osaka University, Professor, 大学院・基礎工学研究科, 教授 (70190098)
TAKATA Toyoo Graduate School of Information Science, NARA Institute of Science and Technology, 情報科学研究科, 助教授 (50216652)
YAMAMOTO Heiichi NARA Institute of Science and Technology, Vice President, 副学長 (40243357)
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| Project Period (FY) |
1996 – 1997
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| Project Status |
Completed (Fiscal Year 1997)
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| Budget Amount *help |
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1997: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1996: ¥1,400,000 (Direct Cost: ¥1,400,000)
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| Keywords | multistage decoding / soft-decision / suboprimum decoding / linear block codes / error performance / decoding complexity / closest-coset decoding / 最大先験確率法 / トレリスダイアグラム / 再帰的最尤復号法 |
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| Research Abstract |
The purpose of this research project is to improve the error performances of multistage decoding schemes by using soft-values between consecutive component decoders. For this sake, the authors have developed n efficient soft-in/soft-out log-MAP recursive decoding algorithm (R-logMap algorithm). The algorithm makes use of the structural properties of linear block codes, and reduces the decoding complexity significantly compared to the conventional BCJR algorithm. For example, computer simulation showed that the complexity of the proposed algorithm necessary for decoding of the second-order Reed-Muller (RM) code of length 128 is only 3% of that of the conventional BCJR algorithm, where the complexity is measured by the number of addition-equivalent operations of metrics. The log-MAP decoding uses some approximations in decoding process to reduce computational complexity and therefore its performance is not as good as the optimal MAP decoding. By modifying the R-logMAP algorithm slightly,
… More
an efficient MAP algorithm can be realized easily. By using the proposed log-MAP and MAP algorithms, the total decoding complexity of the proposed multistage decoding scheme can be reduced significantly. Among multistage decoding schemes, the authors have investigated closest-coset decoding schemes in details. A new multistage iterative decoding scheme can be realized by replacing component decoders of the closest-coset decoder with log-MAP or MAP decpder and introducing a feedback from the last stage to the first stage. The decoding complexity and the error performance of the new scheme are evaluated. Simulation results show that, for the decoding of the second-order RM code of length 64, the proposed scheme with log-MAP (res.MAP) decoding with two (resp.five) repetition improves the performance by 0.4dB (resp.0.5sB) at 10^<-5> block error rate, compared to the conventional closest-coset decoding scheme. The error performance degraduation from the maximum likelihood (ML) decoder is 0.6dB (resp.0.5dB), but the proposed schemes have significantly smaller complexity than the ML decoder. For example, the complexity necessary for the proposed scheme with log-MAP decoding is only one fifth of that of the ML decoder. Less
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