IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences
Online ISSN : 1745-1337
Print ISSN : 0916-8508
Volume E103.A , Issue 11
Showing 1-11 articles out of 11 articles from the selected issue
Regular Section
  • Yepeng CHENG, Hiroyuki OKAMURA, Tadashi DOHI
    Type: PAPER
    Subject area: Numerical Analysis and Optimization
    2020 Volume E103.A Issue 11 Pages 1252-1259
    Published: November 01, 2020
    Released: November 01, 2020
    JOURNALS RESTRICTED ACCESS

    This paper discusses how to compute the parametric sensitivity function in continuous-time Markov chains (CTMC). The sensitivity function is the first derivative of the steady-state probability vector regarding a CTMC parameter. Since the sensitivity function is given as a solution of linear equations with a sparse matrix, several linear equation solvers are available to obtain it. In this paper, we consider Jacobi and successive-over relaxation as variants of the Gauss-Seidel algorithm. In addition, we develop an algorithm based on the Takahashi method for the sensitivity function. In numerical experiments, we comprehensively evaluate the performance of these algorithms from the viewpoint of computation time and accuracy.

    Download PDF (1359K)
  • Fukang LIU, Takanori ISOBE
    Type: PAPER
    Subject area: Cryptography and Information Security
    2020 Volume E103.A Issue 11 Pages 1260-1273
    Published: November 01, 2020
    Released: November 01, 2020
    JOURNALS RESTRICTED ACCESS

    Troika is a recently proposed sponge-based hash function for IOTA's ternary architecture and platform, which is developed by CYBERCRYPT and is now used in IOTA's blockchain. In this paper, we introduce the preimage attack on 2/3 rounds of Troika with a divide-and-conquer approach. Firstly, we propose the equivalent conditions to determine whether a message is the preimage with an algebraic method. As a result, for the preimage attack on two-round Troika, we can search the preimage only in a valid smaller space and efficiently enumerate the messages which can satisfy most of the equivalent conditions with a guess-and-determine technique. Our experiments show that the time complexity of the preimage attack on 2-round Troika can be improved to 379 from 3243. For the preimage attack on 3-round Troika, the MILP-based method is applied to achieve the optimal time complexity, which is 327 times faster than brute force.

    Download PDF (2441K)
  • Natsuki KARIYA, Sumio WATANABE
    Type: PAPER
    Subject area: Information Theory
    2020 Volume E103.A Issue 11 Pages 1274-1282
    Published: November 01, 2020
    Released: November 01, 2020
    JOURNALS RESTRICTED ACCESS

    The test of homogeneity for normal mixtures has been used in various fields, but its theoretical understanding is limited because the parameter set for the null hypothesis corresponds to singular points in the parameter space. In this paper, we shed a light on this issue from a new perspective, variational Bayes, and offer a theory for testing homogeneity based on it. Conventional theory has not reveal the stochastic behavior of the variational free energy, which is necessary for constructing a hypothesis test, has remained unknown. We clarify it for the first time and construct a new test base on it. Numerical experiments show the validity of our results.

    Download PDF (1015K)
  • Ryo SHIBATA, Gou HOSOYA, Hiroyuki YASHIMA
    Type: PAPER
    Subject area: Coding Theory
    2020 Volume E103.A Issue 11 Pages 1283-1291
    Published: November 01, 2020
    Released: November 01, 2020
    [Advance publication] Released: September 03, 2020
    JOURNALS RESTRICTED ACCESS

    We propose a coding/decoding strategy that surpasses the symmetric information rate of a binary insertion/deletion (ID) channel and approaches the Markov capacity of the channel. The proposed codes comprise inner trellis codes and outer irregular low-density parity-check (LDPC) codes. The trellis codes are designed to mimic the transition probabilities of a Markov input process that achieves a high information rate, whereas the LDPC codes are designed to maximize an iterative decoding threshold in the superchannel (concatenation of the ID channels and trellis codes).

    Download PDF (1053K)
  • Gang WANG, Min-Yao NIU, Lin-Zhi SHEN, You GAO
    Type: LETTER
    Subject area: Digital Signal Processing
    2020 Volume E103.A Issue 11 Pages 1292-1295
    Published: November 01, 2020
    Released: November 01, 2020
    [Advance publication] Released: May 14, 2020
    JOURNALS RESTRICTED ACCESS

    In this letter, motivated by the research of Tian et al., two constructions of asymptotically optimal codebooks in regard to the Welch bound with additive and multiplicative characters are provided. The parameters of constructed codebooks are new, which are different from those in the letter of Tian et al.

    Download PDF (166K)
  • Kenji YASUNAGA
    Type: LETTER
    Subject area: Cryptography and Information Security
    2020 Volume E103.A Issue 11 Pages 1296-1298
    Published: November 01, 2020
    Released: November 01, 2020
    [Advance publication] Released: May 14, 2020
    JOURNALS FREE ACCESS

    We present a card-based protocol for computing a three-input majority using six cards. The protocol essentially consists of performing a simple XOR protocol two times. Compared to the existing protocols, our protocol does not require private operations other than choosing cards.

    Download PDF (215K)
  • Haiyang LIU, Hao ZHANG, Lianrong MA, Lingjun KONG
    Type: LETTER
    Subject area: Coding Theory
    2020 Volume E103.A Issue 11 Pages 1299-1303
    Published: November 01, 2020
    Released: November 01, 2020
    [Advance publication] Released: May 12, 2020
    JOURNALS RESTRICTED ACCESS

    In this letter, the structural analysis of nonbinary cyclic and quasi-cyclic (QC) low-density parity-check (LDPC) codes with α-multiplied parity-check matrices (PCMs) is concerned. Using analytical methods, several structural parameters of nonbinary cyclic and QC LDPC codes with α-multiplied PCMs are determined. In particular, some classes of nonbinary LDPC codes constructed from finite fields and finite geometries are shown to have good minimum and stopping distances properties, which may explain to some extent their wonderful decoding performances.

    Download PDF (308K)
  • Biao WANG
    Type: LETTER
    Subject area: Coding Theory
    2020 Volume E103.A Issue 11 Pages 1304-1307
    Published: November 01, 2020
    Released: November 01, 2020
    [Advance publication] Released: May 08, 2020
    JOURNALS RESTRICTED ACCESS

    For low-density parity-check (LDPC) codes, the penalized decoding method based on the alternating direction method of multipliers (ADMM) can improve the decoding performance at low signal-to-noise ratios and also has low decoding complexity. There are three effective methods that could increase the ADMM penalized decoding speed, which are reducing the number of Euclidean projections in ADMM penalized decoding, designing an effective penalty function and selecting an appropriate layered scheduling strategy for message transmission. In order to further increase the ADMM penalized decoding speed, through reducing the number of Euclidean projections and using the vertical layered scheduling strategy, this paper designs a fast converging ADMM penalized decoding method based on the improved penalty function. Simulation results show that the proposed method not only improves the decoding performance but also reduces the average number of iterations and the average decoding time.

    Download PDF (314K)
  • Jinu GONG, Hoojin LEE, Rumin YANG, Joonhyuk KANG
    Type: LETTER
    Subject area: Communication Theory and Signals
    2020 Volume E103.A Issue 11 Pages 1308-1311
    Published: November 01, 2020
    Released: November 01, 2020
    [Advance publication] Released: May 15, 2020
    JOURNALS RESTRICTED ACCESS

    Two-ray (TR) fading model is one of the fading models to represent a worst-case fading scenario. We derive the exact closed-form expressions of the generalized moment generating function (G-MGF) for the TR fading model, which enables us to analyze the numerous types of wireless communication applications. Among them, we carry out several analytical results for the TR fading model, including the exact ergodic capacity along with asymptotic expressions and energy detection performance. Finally, we provide numerical results to validate our evaluations.

    Download PDF (315K)
  • Liping ZHANG, Zongqing LU, Qingmin LIAO
    Type: LETTER
    Subject area: Computer Graphics
    2020 Volume E103.A Issue 11 Pages 1312-1318
    Published: November 01, 2020
    Released: November 01, 2020
    [Advance publication] Released: April 30, 2020
    JOURNALS RESTRICTED ACCESS

    This paper proposes a new and effective convolutional neural network model termed OFR-Net for optical flow refinement. The OFR-Net exploits the spatial correlation between images and optical flow fields. It adopts a pyramidal codec structure with residual connections, dense connections and skip connections within and between the encoder and decoder, to comprehensively fuse features of different scales, locally and globally. We also introduce a warp loss to restrict large displacement refinement errors. A series of experiments on the FlyingChairs and MPI Sintel datasets show that the OFR-Net can effectively refine the optical flow predicted by various methods.

    Download PDF (3524K)
  • Keisuke UTSU, Osamu UCHIDA
    Type: LETTER
    Subject area: Human Communications
    2020 Volume E103.A Issue 11 Pages 1319-1323
    Published: November 01, 2020
    Released: November 01, 2020
    [Advance publication] Released: May 20, 2020
    JOURNALS FREE ACCESS

    The 2019 Typhoon Hagibis (No. 19) caused widespread destruction in eastern Japan. During the disaster, many tweets including rescue request hashtags such as #救助 (meaning #Rescue) and #救助要請 (meaning #Rescue_request) were posted on Twitter. An official disaster information account of the Nagano Prefectural Government asked the public to provide information in the form of damage reports and rescue requests using the hashtag #台風19号長野県被害 (#Typhoon_No.19_Nagano_Prefecture_damage). As a result, many tweets were posted using this hashtag. Moreover, the account contacted the posters of tweets requesting rescue and delivered the information to the Fire Department. In this study, we analyze the circumstances of the above tweets.

    Download PDF (253K)
feedback
Top