Hiroyoshi Morita

Hiroyoshi Morita
The University of Electro-Communications | UEC · Graduate School of Information Systems

Doctor of Engineering

About

110
Publications
5,402
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451
Citations

Publications

Publications (110)
Article
In the above letter [1] , the name of the author Ryuichi Tatsukawa was incorrectly provided as Ryuichi Tatasukawa. The author’s name should appear as Ryuichi Tatsukawa.
Article
This paper proposes two variants of improved Compression by Substring Enumeration (CSE) with a finite alphabet. In previous studies on CSE, an encoder utilizes inequalities which evaluate the number of occurrences of a substring or a minimal forbidden word (MFW) to be encoded. The inequalities are derived from a contingency table including the numb...
Chapter
In this paper, we investigate the electromagnetic field analysis on time and space of a walking human body using Kinect2, a motion sensing device produced by Microsoft. More precisely, we capture walking motions of human body using Kinect2 and applying the simulation model constructed from the captured data to OpenFDTD, we derive the distribution o...
Book
Full-text available
In 1989 we organized the first Benelux‐Japan workshop on Information and Communication theory in Eindhoven, the Netherlands. This year, 2019 we celebrate 30 years of our friendship between Asian and European scientists at the AEW11 in Rotterdam, the Netherlands. Many of the 1989 participants are also present at the 2019 event. This year we have man...
Preprint
Full-text available
This year, 2019 we celebrate 30 years of our friendship between Asian and European scientists at the AEW11 in Rotterdam, the Netherlands. Many of the 1989 participants are also present at the 2019 event. This year we have many participants from different parts of Asia and Europe. It shows the importance of this event. It is a good tradition to pay...
Article
The technique of lossless compression via substring enumeration (CSE) is a kind of enumerative code and uses a probabilistic model built from the circular string of an input source for encoding a one-dimensional (1D) source. CSE is applicable to two-dimensional (2D) sources, such as images, by dealing with a line of pixels of a 2D source as a symbo...
Conference Paper
This paper proposes two variants of improved Compression by Substring Enumeration (CSE) with a finite alphabet. In previous studies on CSE, an encoder utilizes inequalities which evaluate the number of occurrences of a substring and a minimal forbidden word (MFW) to be encoded. Also, its codeword length is proportional to the difference between the...
Article
Full-text available
Distributed line graphs were introduced by Zhang and Liu as an overlay for Peer-to-Peer networks. Distributed line graphs have some useful properties as a network topology, such as out-regular and small diameter, where the former implies that each user possesses a constant size of routing table and the latter means that a reasonably small number of...
Article
In both theoretical analysis and practical use for an antidictionary coding algorithm, an important problem is how to encode an antidictionary of an input source. This paper presents a proposal for a compact tree representation of an antidictionary built from a circular string for an input source. We use a technique for encoding a tree in the compr...
Article
Rivest and Shamir introduced a write-once memory (WOM), a model of storage devices whose storage elements have restrictions on state transitions, and they presented some coding methods to reuse a WOM. An interesting question about a WOM is how efficiently we can reuse it with the best coding method, and as an answer to the question, Fu and Han Vinc...
Book
Full-text available
The 10th Asia-Europe workshop in "Concepts in Information Theory and Communications" AEW10 was held in Boppard, Germany on June 21-23, 2017. It is based on a longstanding cooperation between Asian and European scientists. The first workshop was held in Eindhoven, the Netherlands in 1989. The idea of the workshop is threefold: 1) to improve the comm...
Article
Full-text available
A technique of lossless compression via substring enumeration (CSE) attains compression ratios as well as popular lossless compressors for one-dimensional (1D) sources. The CSE utilizes a probabilistic model built from the circular string of an input source for encoding the source.The CSE is applicable to two-dimensional (2D) sources such as images...
Article
Low-Density Parity-Check (LDPC) codes have been known to exhibit good error correcting performance by using with the Belief Propagation (BP) decoding. The Group Shuffled Belief Propagation (GSBP) decoding, which is a modification of the BP decoding, can exhibit better performance than BP decoding by suitably grouping variable nodes in a Tanner grap...
Article
Full-text available
The demand of two-dimensional source coding and constrained coding has been getting higher these days, but compared to the one-dimensional case, many problems have remained open as the analysis is cumbersome. A main reason for that would be because there are no graph representations discovered so far. In this paper, we focus on a two-dimensional fi...
Research
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We establish interesting formulas with respect to Catalan numbers and Motzkin numbers that generalize the well-known convolutional formula of Catalan numbers, that is, so-called Euler-Segner formula.
Conference Paper
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We introduce many BGF's related to the basic characteristics appeared in random walks through the symbolic method. By deeply analyzing these BGF's, we can obtain a lot of properties of characteristics contained in random walks. As by-products, we encounter many interesting combinatorial identities.
Conference Paper
Full-text available
We show an interesting fact that a quarter of paths of random walks of any length n( ≥ 2) have two maximums. Moreover, it holds that the asymptotic distribution of number of maximums of paths obeys the geometric distribution of parameter 1/2. Furthermore, we provide the generating function for counting number of paths jointly with number k of maxim...
Article
This paper shows that a two-pass universal antidictionary coding method is asymptotically optimal for stationary ergodic sources with a finite alphabet. To prove the results, we propose a new compact tree representation of an antidictionary. We also extend the lossless compression algorithm proposed by Dubé and Beaudoin, called CSE, from the binary...
Article
Full-text available
This paper proposes a new two-dimensional antidictionary coding for a given rectangle. An antidictionary is the set of all the minimal forbidden rectangles for an input rectangle. The proposed encoder outputs a pair of an antidictionary and a unique polyomino which appears only once in an input rectangle as a codeword. The input rectangle can be de...
Article
Wu and Jiang proposed a code for rewriting Write-Once Memories (WOM's), and they called it position modulation code. In this paper, we propose an analogy of their code for non-binary WOM's. We show that the proposed code asymptotically achieves the sum rate at least half of that achievable by the best possible code.
Article
Zhang and Liu introduced in 2012 a technique using distributed line graphs (DL graphs) to construct a DHT with constant size of routing information at each peer. They also introduced properties of DL graphs, but some results are described without detailed explanations and analysis. In this paper, we focus on the in-degree of a vertex (the number of...
Article
The efficiency of Error Correcting Codes (ECCs) arises when data should be transmitted via noisy channel. Many types of ECCs have been proposed so far, but ECCs with low encoding/ decoding complexity are demanded when energy consumption is highly considered (e.g. networks using nanoscale devices). For such a situation, Irregular Repeat Accumulate (...
Conference Paper
Full-text available
Conceptionally the User Datagram Protocol (UDP) should be well-suited for real-time applications, e.g., for Voice over IP (VoIP). However, many such applications, e.g., Skype, use the Transmission Control Protocol (TCP) either as a primary protocol or as a backup protocol when UDP is blocked, despite TCP's flow control-related data delays. This pap...
Conference Paper
Full-text available
In this talk, we provide a simple proof on an interesting equality connecting the number of permutations of 1, ..., n with k runs, i.e., Eulerian numbers to the volumes of slices between k-1 and k of the n-dimensional hypercube along the diagonal axis. The proof is simple and elegant, but the detail structures in the problem are left to be unclear....
Article
This paper presents a real-time and memory-efficient arrhythmia detection system that uses antidictionary coding for the analysis and classification of electrocardiograms (ECGs). The measured ECG signals are encoded using a lossless antidictionary encoder, and the system subsequently uses the compression rate to distinguish between normal beats and...
Article
A shift of finite type (SFT) is a set of all bi-infinite sequences over some alphabet which is characterized by a finite set of forbidden words. It is a typical example of sofic shifts and has been used in media storage area, such as CD's or DVD's. The study of sofic shifts is based on graph theory, and the irreducibility of shifts is an important...
Conference Paper
In this paper, we propose Wall Pass Algorithm (WPA). WPA presents a function to forward the messages to a neighboring area. We evaluate the performance of a geographic location-based distributed routing (GDR) system when the mobile terminals are moving. The results show that GDR and CAN have the same mean and the variance of the path length and the...
Conference Paper
Full-text available
Lossless data compression via substring enumeration (CSE) has been proposed by Dubé and Beaudoin in 2010. The CSE outputs its encoder called compacted substring automaton as a codeword, and an efficient representation of the automaton is also proposed. In this paper, we prove an isomorphism between compacted substring automaton and antidictionary a...
Article
We give an evaluation of limit variance in the central limit theorem for waveletbased estimator of the Hurst index of fractional Brownian motion (FBM). is the variance of a certain linear sum (with respect to scale j ) of random variables. As a result, contribution to variance of the linear form turns out to be mostly its diagonal part components,...
Conference Paper
Full-text available
In this paper, we establish interesting formulas with respect to Catalan numbers and Motzkin numbers that generalize the well-known convolutional formula of Catalan numbers, that is, so-called Euler-Segner formula. Furthermore, we provide examples of application of these formulas in studying combinatorial structures, that is, the determination of d...
Conference Paper
There are two efficient static data compression algorithms called an antidictionary coding and a lossless data compression via substring enumeration coding. We prove that both of the encoders are isomorphic.
Conference Paper
An antidictionary, a set of words that never appear in a given string, is a useful data structure for source coding as well as other fields of computer sciences. A fast and memory-efficient algorithm for constructing antidictionaries by means of suffix array is presented. We prove that the proposed algorithm constructs an antidictionary array with...
Conference Paper
Churn resilience is an important issue for current Peer-to-Peer(P2P) networks, where peers dynamically and freely join and leave the system with or without warning. In this paper we focus on improving an existing anonymous peer-to-peer network design by adding churn-resilience to it. Churn resilience is achieved by employing the properties of thres...
Article
The present research paper introduces and discusses a novel approach to business-matching and recommending systems for next-generation e-marketplaces. The goal from this approach is to shift the focus from search-oriented matching, toward assistance-providing business matching, especially for small businesses. The proposed matching system makes use...
Article
Full-text available
This paper describes a novel approach for addressing the issue of business-matching and recommending in business-to-business e-marketplaces. The presented matching system makes use of Collective Intelligence (CI) means for identifying and recommending business opportunities that are best correlated with the user's need. The objective from this appr...
Article
An antidictionary is in particular useful for data compression. Static construction algorithms of antidictionaries with linear complexity have been proposed. However, the con- struction algorithms do not work in a dynamic manner with linear complexity. In this paper, we propose a dynamic construc- tion algorithm of an antidictionary with linear com...
Article
This paper proposes a geographic location-based distributed routing (GDR) system. GDR system is a structured distributed information lookup and routing (SDILR) system that provides information lookup, based on the geographic latitude and longitude coordinates, where each node is given the coordinates as an identifier (ID) and manages an overlay rou...
Article
The present work proposes and describes a novel approach to business-matching and recommending systems, for the next-generation e-marketplaces, with a focus on the needs and realities of small business. The proposed matching system makes use of Collective Intelligence (IC) means to identify and recommend the best matching business opportunities for...
Article
Full-text available
An antidictionary is particularly useful for data compression and on line electrocardiogram (ECG) lossless compression algorithms using antidictionaries have been proposed They work in real time with constant memory and give better compression ratios than traditional lossless data compression algorithms while they only deal with ECG data on a binar...
Article
Full-text available
Integer codes correct errors of a given type, which means that for a given communication channel and modulator we can choose the type of the errors (which are the most common) then construct integer code capable of correcting those errors. A new general construction of single (±1) error correctable integer codes will be presented. Comparison betwee...
Conference Paper
This paper proposes a new on-line antidictionary code with linear time. The proposed algorithm uses a subset of antidictionary which length of the elements is at most a given fixed length. It is proved that the time complexity of this algorithm is linear with respect to the string length. Its effectiveness is demonstrated by simulation results.
Conference Paper
Full-text available
We present new algorithms to detect and track multiple moving objects in a static surveillance video that uses MPEG-2 compression. The algorithm detects moving objects based on the location of field-based motion estimated macroblocks in inter-prediction frames, and tracks their movements along video scene by using an extension of Kalman filter that...
Conference Paper
In this paper we propose a mutually anonymous protocol for decentralized Peer-to-Peer (P2P) networks. The protocol is a combination between the Secret-Sharing-Based Mutual Anonymity Protocol (SSMP) and the information slicing technique. The proposed protocol realizes the initiator's and responder's anonymity by using the SSMP in which the complete...
Article
Due to the lack of quality guarantees, it's very difficult to deploy IPTV services in the current internet, especially in a NGN network, the core IMS framework interconnects different access networks which have differing amounts of bandwidth available and varying client terminals. The ETSI TISPAN standards allow adaptation multimedia content by tra...
Article
Integer codes are very flexible and can be applied in different modulation schemes. A soft decoding algorithm for integer codes will be introduced. Comparison of symbol error probability (SEP) versus signal-to-noise ratio (SNR) between soft and hard decoding using integer coded modulation shows us that we can obtain at least 2 dB coding gain. Also,...
Article
Full-text available
An antidictionary code is a lossless compression algorithm using an antidictionary which is a set of minimal words that do not occur as substrings in an input string. The code was proposed by Crochemore et al. in 2000, and its asymptotic optimality has been proved with respect to only a specific information source, called balanced binary source tha...
Conference Paper
Full-text available
An error-resilient variable-length arithmetic code is presented whose codewords are represented by binary digits. The input sequence is partitioned in subsequences, each of which is individually encoded using an arithmetic coding scheme with an integrated bit-stuffing technique that restricts the number of consecutive ones in the output sequence. A...
Conference Paper
With the increasing demand of video services, efficient detection approaches are required to deal with the increasing amount of sport video like baseball, tennis and soccer. Specially, due to characteristics of soccer game, timeliness is a foremost. So apart from efficient performance, real-time or near real-time performance is crucial. In this pap...
Conference Paper
An anti-dictionary is in particular useful for data compression, and it consists of minimal forbidden words for a given string. We derive the average length M<sub>n</sub> of minimal forbidden words in strings of length n under a stationary ergodic source with entropy H which takes values on a finite alphabet. For the string length n, we prove, log...
Article
Delivering video streaming service over the Internet encounters some challenges. Two of them are heterogeneity of networks capacity and variability of video data rate. The capacity of network segments are constrained. Meanwhile, the rate of video data to be transmitted is highly variable in order to get near-constant images quality. Therefore, to s...
Conference Paper
A new construction of double error correctable integer codes and their application to QAM scheme are presented. Soft decoding algorithm for multiple error correctable integer code which are suited to any modulation scheme (QAM, PSK, ASK) will be introduced. Comparison of bit error rate (BER) versus signal-to-noise ratio (SNR) between soft and hard...
Conference Paper
Two sliding window variations of an adaptive arithmetic coding method based on dynamic antidictionaries of the input data are proposed. Due to a limited size of sliding window, the proposed methods are memory-efficient and suitable for handling an extremely long string in constant space. Moreover, one of the proposed methods works in linear time wi...
Article
Full-text available
This paper proposes on-line electrocardiogram (ECG) loss-less data compression based on antidictionaries. An antidic-tionary is the set of all words of minimal length that never appear in the string. The proposed methods use the coders constructed by a training sequence of constant length of ECG, so that they work with an on-line manner in constant...
Article
Full-text available
Codes capable to correct two errors of value 1 in a codeword are con- structed and studied. Large number of experiments simulating the implementation of several double 1-error correctable codes in QAM-modulation schemes have been carried out. The obtained results present in graphical form the performance of the coded modulation schemes based on the...
Article
In this paper some of the properties of the (t, n) threshold secret sharing schemes, based on the generalized vector space construction, are discussed. The relations between the size of the shares and the number of the users n in the (t, n) threshold secret sharing schemes are presented. Moreover, it is shown how a qualified set of users can effici...
Article
Constructing ideal (t, n) threshold secret sharing schemes leads to some limitations on the maximum number of users, that are able to join the secret sharing scheme. We aim to remove these limitations by reducing the information rate of the constructed threshold secret sharing schemes. In this paper we propose recursive construction algorithms of (...
Conference Paper
Now a day, the used of biometrics as part of the security systems have been increasing; to detect, classify and to track human motion with a high precision are part of this demand, for that reason many approaches have been proposed and, since computer vision let us to manipulated digital image sequences many of these techniques use the information...
Article
Full-text available
Codes capable to correct two errors of value ±1 in a codeword are con-structed and studied. Large number of experiments simulating the implementation of several double ±1-error correctable codes in QAM-modulation schemes have been carried out. The obtained results present in graphical form the performance of the coded modulation schemes based on th...
Article
Full-text available
The antidictionary of a string is the set of all words of minimal length that never appear in this string. Antidictionaries are in particular useful for source coding. We present a fast and memory-efficient algorithm to construct an antidictionary using a suffix tree. It is proved that the complexity of this algorithm is linear in space and time, a...
Conference Paper
In this paper we propose an algorithm to adjust the transmission bit-rate of variable-bit-rate (VBR) MPEG video data by using a combination of transcoding and bit-rate smoothing algorithm. The algorithm works by smoothing out the bit-rate of high variance MPEG video data and when necessary transcodes some video frames in order to keep the video tra...
Conference Paper
This paper proposes an on-line data compression based on antidictionaries with linear time. The proposed algorithm works using only suffix trees without constructing of antidictionaries, and we prove that the time complexity of this algorithm is linear with respect to the string length. Furthermore, the proposed algorithm produces the tree model ba...
Conference Paper
Integer codes, defined over integer rings, allow the correction of single cross errors with distance 1 in a signal point constellation on a two-dimensional lattice. Several construction methods support the construction of integer codes that give constellations that have a variety of shapes. In this paper, we characterize all constellations that can...
Article
This paper considers the universal coding problem for stationary ergodic sources with countably infinite alphabets. We propose modified versions of LZ77 and LZ78 codes for sources with countably infinite alphabets. Then, we show that for any source μ ...
Conference Paper
We consider the class of integer codes that are capable of correcting single errors in a two-dimensional lattice (H. Morita et al., 2003). Integer codes, defined over integer rings, allow the correction of single errors with distance 1. In this paper, we extend our previous results (H. Morita et al., 2003). We will detail the derivation of an upper...
Conference Paper
Full-text available
An antidictionary of a binary string is a set of words of minimal length that never appear in this string. Antidictionaries are in particular useful for source coding. We present a fast and memory-efficient algorithm to construct an antidictionary for a binary string using a suffix tree. It is proved that the complexity of this algorithm is linear...
Article
Full-text available
SUMMARY In this paper, we propose a protocol for multicast commu- nication called Multicast Datagram Transfer Protocol (MDTP) to provide multicast for video broadcasting service on the Internet. MDTP is a one- to-many multicast communication protocol, which is constructed based on IPv4 unicast protocol by utilizing IP Router Alert Option, and it us...
Conference Paper
Starting from the root, extend k branches and append k children with probability p, or terminate with probability q=1-p. Then, we have a finite k-ary tree with probability one if 0≤p≤1/k. Moreover, we give the expectation and variance of the length of ideal codewords for representing the finite trees. Furthermore, we establish the probability of ob...
Conference Paper
Full-text available
A combination of multicast datagram transfer protocol (MDTP) and overlay multicast system for video broadcasting service over the Internet is proposed. Both are protocols for multicast communication system, which is required to deliver video broadcasting service because the conventional unicast system may waste the network resources. This hybrid sy...
Conference Paper
A new class of DC-free codes of odd length is presented. The new codes, related to polarity-switch (PS) codes, make use of a redefinition of the running digital sum. The spectral efficiency of the new codes is determined, and it is shown that they provide better power suppression in the low-frequency region than classical PS codes
Article
Full-text available
A rate splitting algorithm is presented for a multiple video transmission system to transfer the aggregation (or statical multiplexing) of multiple video streams to multiple clients so that each client can receive the requested video stream with the reliable fidelity. Computer simulations for transmission of a set of 128 MPEG compressed video strea...
Article
Full-text available
International audience A tight upper bound of the size of the antidictionary of a binary string is presented. And it is shown that the size of the antidictionary of a binary sting is always smaller than or equal to that of its dictionary. Moreover, an algorithm to reconstruct its dictionary from its antidictionary is given.
Conference Paper
In this paper, we are concerned with single source multicast communication models for scalable video application in IPv4 network using unicast protocol. We propose a new protocol called multicast datagram transfer protocol (MDTP) which utilizes the IP option field of the IPv4 header. MDTP enables routers responsible to replicate and forward MDTP pa...
Conference Paper
Coded modulation refers to the process of combined and jointly optimized channel coding and modulation scheme. In this paper, block coded modulation using integer codes and its performance is evaluated by deriving a formula of its bit error probability for AWGN channel. The probability of correct detection of the received signal is a square of the...