Presentation 2017-03-09
Trellis Reduction for Tail-Biting Convolutional Codes Using Characteristic Matrices and Cyclically Shifted Code-Subsequences
Masato Tajima,
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Abstract(in Japanese) (See Japanese page)
Abstract(in English) Trellis reduction for tail-biting convolutional codes is investigated. A given tail-biting (TB) convolutional code is regarded as an (n, k) linear block code C. Then a characteristic matrix for C can be computed. Here consider the case where some k characteristic generators, which consist of the main generators and their cyclic shifts, can generate the same code C. We see that these characteristic generators form a (scalar) generator matrix associated with a (polynomial) generator matrix of another convolutional code. In this case, if the constraint length of the obtained generator matrix is smaller than that of the original one, then trellis reduction is accomplished. Even if this kind of reduction is not possible, there are cases where a newly obtained generator matrix contains a monomial factor in some column. Then there is a possibility that the generator matrix is reduced by sweeping the monomial factor out of the column. Note that this operation corresponds to cyclically shifting the corresponding code-subsequence to the left. In this way, the modified TB paths are represented using a reduced trellis with less state complexity.
Keyword(in Japanese) (See Japanese page)
Keyword(in English) tail-biting convolutional codes / tail-biting trellis / characteristic matrix / cyclically shifted code-subsequence / trellis reduction
Paper # IT2016-108,ISEC2016-98,WBS2016-84
Date of Issue 2017-03-02 (IT, ISEC, WBS)

Conference Information
Committee ISEC / WBS / IT
Conference Date 2017/3/9(2days)
Place (in Japanese) (See Japanese page)
Place (in English) TOKAI University
Topics (in Japanese) (See Japanese page)
Topics (in English) joint meeting of IT, ISEC, and WBS
Chair Masahiro Mambo(Kanazawa Univ.) / Fumiaki Maehara(Waseda Univ.) / Masayoshi Ohashi(Fukuoka Univ.)
Vice Chair Kazuto Ogawa(NHK) / Atsushi Fujioka(Kanagawa Univ.) / Masanori Hamamura(Kochi Univ. of Tech.) / Fumie Ono(NICT) / Jun Muramatsu(NTT)
Secretary Kazuto Ogawa(Toshiba) / Atsushi Fujioka(Tohoku Univ.) / Masanori Hamamura(Tokyo City Univ.) / Fumie Ono(Mitsubishi Electric) / Jun Muramatsu(Wakayama Univ.)
Assistant Toshihiro Ohigashi(Tokai Univ.) / Yuuji Suga(IIJ) / Atsuo Inomata(Tokyo Denki Univ.) / Yusuke Kozawa(Tokyo Univ. of Science) / Akira Nakamura(Tokyo Univ. of Science) / Ryohei Nakamura(National Defense Academy) / Mitsugu Iwamoto(Univ. of Electro-Comm.)

Paper Information
Registration To Technical Committee on Information Security / Technical Committee on Wideband System / Technical Committee on Information Theory
Language JPN
Title (in Japanese) (See Japanese page)
Sub Title (in Japanese) (See Japanese page)
Title (in English) Trellis Reduction for Tail-Biting Convolutional Codes Using Characteristic Matrices and Cyclically Shifted Code-Subsequences
Sub Title (in English)
Keyword(1) tail-biting convolutional codes
Keyword(2) tail-biting trellis
Keyword(3) characteristic matrix
Keyword(4) cyclically shifted code-subsequence
Keyword(5) trellis reduction
1st Author's Name Masato Tajima
1st Author's Affiliation *(*)
Date 2017-03-09
Paper # IT2016-108,ISEC2016-98,WBS2016-84
Volume (vol) vol.116
Number (no) IT-504,ISEC-505,WBS-506
Page pp.pp.61-66(IT), pp.61-66(ISEC), pp.61-66(WBS),
#Pages 6
Date of Issue 2017-03-02 (IT, ISEC, WBS)