Faculty of Science and Technology

Shibuya Tomoharu

  (澁谷 智治)

Profile Information

Affiliation
Professor, Faculty of Science and Technology, Department of Information and Communication Sciences, Sophia University
(Concurrent)Dean of the Faculty of Science and Technology
Degree
博士(工学)(Apr, 1999, 東京工業大学)

Researcher number
20262280
J-GLOBAL ID
200901097688266540
researchmap Member ID
1000181747

External link

1991- Applications and fundamental aspects on the error correcting codes, especially on the parameters of algebraic codes
2001- On the performance of LDPC codes and their decoding algorithm
2008- On the convergence behavior of the iterative decoding
2010- Efficient encoding algorithm for linear codes and related topics
Coding for Non-volatile memory
2011- Construction of quantum error correcting codes

On the convergence bihavior of the iterative decoding

(Subject of research)
Error Correcting Codes with Iterative Decoding
Researches in the Parameters of Algebraic Codes


Papers

 63
  • Daisuke Hibino, Tomoharu Shibuya
    122(427) 325-330, Mar, 2023  Last authorCorresponding author
  • Mariko FUJII, Tomoharu SHIBUYA
    IEICE TRANSACTIONS on Information and Systems, E.103-D(1) 11-24, Jan 1, 2020  Peer-reviewed
  • Tomoharu Shibuya, Takeru Sudo
    IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences, E100A(12) 2558-2571, Dec 1, 2017  Peer-reviewed
    In this paper, we propose a group theoretic representation suitable for the rank-modulation (RM) scheme over the multi-cell ranking presented by En Gad et al. By introducing an action of the group of all permutation matrices on the set of all permutations, the scheme is clearly reformulated. Moreover, weintroduce the concept ofr-dominating sets over the multi-cell ranking, which is a generalization of conventional dominating sets, inthe design of rank-modulation rewriting codes. The concept together with the proposed group theoretic representation yields an explicit formula of an upper bound on the size of the set of messages that can be stored in the memory by using RM rewriting codes over multi-cell ranking. This bound enables us to consider the trade-off between the size of the storable message set and the rewriting cost more closely. We also provide a concrete example of RM rewriting code that is not available by conventional approaches and whose size of the storable message set can not be achieved by conventional codes.
  • Tomoharu Shibuya, Takeru Sudo
    PROCEEDINGS OF 2016 INTERNATIONAL SYMPOSIUM ON INFORMATION THEORY AND ITS APPLICATIONS (ISITA 2016), 131-135, 2016  
    In this paper, we study rank-modulation (RM) rewriting codes based on dominating sets. By introducing a special class of dominating sets in a construction of RM rewriting codes and employing the notion of a group action in an analysis of those codes, we succeeded to construct. RM rewriting codes based on the dominating sets that maximize the amount of stored data under the limit of rewriting cost for flash memories with 4 and 5 cells.
  • Keisuke Kodaira, Mihoko Wada, Tomoharu Shibuya
    IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES, E97A(11) 2247-2253, Nov, 2014  Peer-reviewed
    The amplitude damping (AD) quantum channel is one of the models describing evolution of quantum states. The construction of quantum error correcting codes for the AD channel based on classical codes has been presented, and Shor et al. proposed a class of classical codes over F-3 which are efficiently applicable to this construction. In this study, we expand Shor's construction to that over F-7, and succeeded to construct an AD code that has better parameters than AD codes constructed by Shor et al.

Misc.

 44
  • Shibuya Tomoharu, Sudo Takeru
    電子情報通信学会技術研究報告 = IEICE technical report : 信学技報, 116(33) 115-120, May 19, 2016  
  • Shibuya Tomoharu, Sudo Takeru
    電子情報通信学会技術研究報告 = IEICE technical report : 信学技報, 116(34) 115-120, May 19, 2016  
  • Kanbayashi Yuya, Shibuya Tomoharu
    Technical report of IEICE. ISEC, 112(461) 113-118, Mar 7, 2013  
    Rank Modulation code is a recoding code expressing information by using the mutual relation between the level of electric charge of each cell constituting a flash memory. Compressed encoding is one of the rank modulation encodings that employ the push up operation to realize a state transition of memory. In this study, we investigate a code constructions based on the dominating set of a transition graph, which is known as one of techniques to inclease the capacity of memory and decrease frequency of the occurrence of the block erasure in the compressed encoding. As a result, we propose a new algorithm to construct a dominating set. Moreover, we show a sufficient condition for the proposed algorithm to generate a minimal dominating set. In addition, we give a concretely an example of minimal dominating set for a memory constituting 5 cells.
  • IHARA Hiroyuki, SHIBUYA Tomoharu
    IEICE technical report. Information theory, 112(124) 85-89, Jul 12, 2012  
    Spatially coupled (SC) low-density parity-check (LDPC) codes are denned by bipartite graphs that are obtained by assembling prototype graphs. The combination and connection of prototype graphs are designated by specifying some parameters, and Kudekar et al. showed that BP threshold of the ensemble of SC LDPC codes agrees with MAP threshold of the ensemble of regular LDPC codes when those parameters are grown up so that the code length tends to infinity. When we design SC LDPC codes with practical code length, however, it is not clear how to set those parameters to enhance the performance of SC LDPC codes. In this paper, we provide the result of numerical experiments that suggest the dependence of error performance of SC LDPC codes over BEC on their design parameters.

Books and Other Publications

 6

Presentations

 14
  • Daisuke Hibino, Tomoharu Shibuya
    Technical Committee Meeting on Information Theory, Mar 15, 2023
  • Taiyu Kamiyama, Yuta Ugaya, Keisuke Kodaira, Tomoharu Shibuya
    2018 The International Symposium on Information Theory and Its Applications, Oct 28, 2018, Engineering Sciences Society, IEICE
    conventional secret sharing, password protected secret sharing (PPSS) was invented. Recently, Nakahara et al. improved Ogata's multiple-use PPSS (mPPSS), which protects multiple data by one password, by employing secure computation known as CSEC70 method in the user authentication. In this paper, we propose an attack on Nakahara's mPPSS that presumes on a security hall in the adoption of CSEC70 method. Then, we show that the proposed attack enables an administrator of any server of the system to disclose the password of an arbitrary user in Nakahara's mPPSS.
  • Tomoharu Shibuya
    Japan-Singapore Workshop on Coding and Information Theory, Mar 4, 2018, School of Physical & Mathematical Sciences, Nanyang Technological University
    In this talk, a group theoretic representation suitable for the rank-modulation (RM) scheme over the multi-cell ranking developed by En Gad et al. is presented. By introducing an action of the group of all permutation matrices on the set of all permutations, the scheme is clearly reformulated. Moreover, we introduce the concept of r-dominating sets over the multi-cell ranking, which is a generalization of conventional dominating sets, in the design of rank-modulation rewriting codes. The concept together with the presented group theoretic representation helps to yield an explicit formula of an upper bound on the size of the set of messages that can be stored in the memory by using RM rewriting codes over multi-cell ranking. We also note that this bound enables us to consider the trade-off between the size of the storable message set and the rewriting cost more closely.
  • 須藤 尊, 渋谷 智治
    電子情報通信学会情報理論研究会, Jan 20, 2017, 電子情報通信学会
  • Tomoharu Shibuya, Takeru Sudo
    Conference of Technical Committee on Information Theory, May 20, 2016, IEICE

Research Projects

 13