Papers by Yoshikuni Onozato
Ieice Transactions on Fundamentals of Electronics Communications and Computer Sciences, Nov 25, 2000
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SUMMARY Multiple antenna systems are promising archi- tectures for overcoming the effects of mult... more SUMMARY Multiple antenna systems are promising archi- tectures for overcoming the effects of multi-path interference and increasing the spectrum efficiency. In order to be able to investi- gate these systems, in this article, we derive generalized spatial correlation equations of a circular antenna array for two typical angular energy distributions: a Gaussian angle distribution and uniform angular distribution. The generalized
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Performance of Distributed Systems and Integrated Communication Networks, 1991
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IEEE Transactions on Communications, 1985
ABSTRACT We develop a new tool for performance evaluation of a multiaccess communication system. ... more ABSTRACT We develop a new tool for performance evaluation of a multiaccess communication system. We give an explicit detailed analytic description of a cusp catastrophe in a computer communication system. An approximate model is formulated for a slotted Aloha system assuming a single buffer, based on the Markovian model studied by Lam [2] and Carleial [3]. Next, we outline the research on quantitative processing of thrashing and its results. Sudden changes, which can be observed in the throughput rate, the average delay, and the average number of backlogged users, are induced by smooth alterations of control parameters in the behavior of a slotted Aloha system. These catastrophic phenomena, such as long lasting periods of vanishing throughput rate and very high delays, are analyzed in line with catastrophe theory. The system behavior in a slotted Aloha system is characterized by the cusp catastrophe. In particular, introducing a new parameter σ in our model, we make it clear why and in what cases these catastrophic phenomena occur. The amount of change is also estimated.
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2008 7th Asia-Pacific Symposium on Information and Telecommunication Technologies, 2008
ABSTRACT Stream control transmission protocol (SCTP) is a transport layer protocol for the next-g... more ABSTRACT Stream control transmission protocol (SCTP) is a transport layer protocol for the next-generation Internet. In this paper, we investigate optimally condition for MPEG 4 video communication with SCTP in 802.11 wireless access media. We focus on the multi-streaming feature and the partial reliability extension in SCTP and compare performance of MPEG4 video quality under the policy w th/without differentiated retransmission among streams. Differentiated policy allows packets belonging to a specific stream to be retransmitted, while packets are transmitted exactly one time (no retransmissions) in homogeneous policy. By computer simulation, we show that SCTP can (1) improve the video quality by exploiting the multi-streaming and partial reliability features, and (2) enhance the video transmission quality can by adjusting SCTP fast retransmit threshold.
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Lecture Notes in Computer Science, 2005
In this paper, we investigate the communication performance of one-dimensional cellular networks ... more In this paper, we investigate the communication performance of one-dimensional cellular networks from the viewpoint of the mobile node’s speed with the simulation method assuming various types of speed distributions. Simulation results are measured as blocking probabilities of both new and handoff calls and call completion probability. We can observe the phenomenon that blocking probabilities of both new and handoff calls are not related to the mobile node’s speed distribution, but the call completion probability concerns with that under overloaded situation when the blocking probabilities are not small.
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Lecture Notes in Computer Science, 2001
ABSTRACT In this paper, we propose an approach to solve the power allocation issues in a DS-CDMA ... more ABSTRACT In this paper, we propose an approach to solve the power allocation issues in a DS-CDMA cellular system using genetic algorithms (GAs). The transmitter power control has proven to be an efficient method to control cochannel interference in cellular PCS, increase bandwidth utilization and balance the wireless services. Most of the previous studies have assumed that the transmitter power level is controlled in a constant domain under the assumption of uniform distribution of users in the coverage area or in a continuous domain. In this paper, the optimal Centralized Power Control (CPC) vector is characterized and its optimal solution for CPC is presented using GAs in a large scale DS-CDMA cellular system.
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Lecture Notes in Computer Science, 2000
ABSTRACT CDMA has been proven to be one of the promising mainstream multiaccessing techniques in ... more ABSTRACT CDMA has been proven to be one of the promising mainstream multiaccessing techniques in the third-generation mobile system. In this paper, we fully investigated the performance of a CDMA system which supports the data users. In the proposed algorithm[1][2], data user’s burst admission is permitted based on the load situation of the system. Performance measures obtained included the system capacity, ISR limitation and the constraint set between the load of the system and the allowed maximum data rate. Based on the numerical results, we see the feasibility of integrated services supported in the CDMA system, where the burst admission is available, and what kinds of data services can be supported over the coverage area.
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2009 IEEE 20th International Symposium on Personal, Indoor and Mobile Radio Communications, 2009
In this paper, we introduce an extension of Stream Control transmission Protocol (SCTP) aiming fo... more In this paper, we introduce an extension of Stream Control transmission Protocol (SCTP) aiming for improving the efficiency of delay-sensitive transmission of multimedia data such MPEG-4 traffic. Briefly, our SCTP extension exploits one-way delay between SCTP endpoints, which allows the SCTP extension to retransmit lost packets selectively depending on whether the lost packets would still arrive before the schedule time. By computer simulations, we show that our extension provides the better performance than a simple retransmission method based on lifetime under both wired and wireless access links. Specifically, we confirm that our extension maintains the fair sharing of bandwidth among the legacy TCP flows, irrelevant to wired and wireless access links.
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The 2nd IEEE Asia-Pacific Service Computing Conference (APSCC 2007), 2007
ABSTRACT The stream control transmission protocol (SCTP) is a reliable transport layer protocol s... more ABSTRACT The stream control transmission protocol (SCTP) is a reliable transport layer protocol standardized by IETF as RFC 2960 in 2000. Because of its attractive features such as multi-homing and multi-streaming, SCTP has received much attention from researchers in worldwide with an expectation that would address limitations of TCP performance encountered in wired-cum-wireless networks. In this paper, we focus on the multi-streaming feature of SCTP. Making use of the partial reliability extension in SCTP, we compare performance of MPEG-4 video quality under the policy with/without differentiated retransmission among streams. Differentiated policy allows packets belonging to a specific stream to be retransmitted, while packets are transmitted exactly one time (no retransmissions) in homogeneous policy. We show by simulation, that video object traffic streams encoded by MPEG-4 can be efficiently conveyed under lossy link by SCTP with differentiated policy among streams than with homogeneous policy. We further analyze and show, also by simulation, that SCTP with optimally tuned retransmission policy can minimize the play- out delay time as well as keep high quality video decoding of MPEG-4 traffic stream.
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2010 International Conference on Computational Intelligence and Software Engineering, 2010
ABSTRACT In order to obtain high spectral efficiency and high-rate packet transmission, this pape... more ABSTRACT In order to obtain high spectral efficiency and high-rate packet transmission, this paper has proposed a STBC-OFDM system to solve the problem of Multi-fading Channels for wideband wireless communication system. Considering the Frequency Selective Channels (FSC), the paper gives the many simulation results of BER based on SNR when the system adopted different number of receiving and transmitting antennas, and with or without random interleaver. The results show the detail impact of FFT and the number of sub-carriers on the system. The interleaver can improve the performance of system greatly and will get a reasonable robustness in future wireless system.
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2007 International Conference on Wireless Communications, Networking and Mobile Computing, 2007
Accurate power control is an essential requirement in the design of cellular code division multip... more Accurate power control is an essential requirement in the design of cellular code division multiple access (CDMA) systems. The performance analysis for the three-dimensional air-to-ground (AG) cellular system becomes an important issue. In this paper, assuming that the imperfect power control follows log-normal statistics, the capacity and outage probability of the aeronautical communication system are examined and quantified. The system
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IEEJ Transactions on Electronics, Information and Systems, 2004
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2009 5th International Conference on Wireless Communications, Networking and Mobile Computing, 2009
ABSTRACT This paper presents a reasonable program that use orthogonal frequency division multiple... more ABSTRACT This paper presents a reasonable program that use orthogonal frequency division multiplexing(OFDM) technology to reduce inter-symbol interference (ISI) to improve the performance of space-time coding (STC) under frequency selective fading channel. Analyze the STC-OFDM system under the combination of STC and OFDM technology based on IEEE802.11a wireless standards.Monte Carlo method is adopted in simulation. The simulation results show that the combination of STBC and OFDM technology is superior to the combination of VBLAST and OFDM technology; FFT points and the number of subcarriers of the system has a certain impact on performance; Random interleaver can improve the performance of system under multipath fading channel and get a reasonable robustness under a variety of channels.
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This paper focuses on an analysis of an orthogonal-variable-spreading-factor (OVSF) codes assignm... more This paper focuses on an analysis of an orthogonal-variable-spreading-factor (OVSF) codes assignment scheme called the hybrid OVSF-code assignment (HCA). We propose HCA as an alternative solution for OVSF code assignment in order to mitigate so-called code blocking in OVSF-CDMA and to correspond to each service equally. We present the performance evaluation of HCA by computer simulations.
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In this article, the co-existence of TDMA and W-CDMA spectrum sharing system (TDMA/W-CDMA overlai... more In this article, the co-existence of TDMA and W-CDMA spectrum sharing system (TDMA/W-CDMA overlaid system) with cellular architecture is discussed. In this system, both systems share the same frequency band to improve the spectrum efficiency. The overall rate and spectrum efficiency of the system are calculated for the forward link (down-link) in the presence of the AWGN channel. Taking into account the path loss and shadow fading loss in this system with cellular architecture, W-CDMA applying interference cancellation (IC) shows a substantial difference in spectrum efficiency, the overlaid system can provide a greater overall rate and higher spectrum efficiency than a single multiple access-based system such as the TDMA system or W-CDMA system.
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The authors study the fundamental characteristics of the congestion caused by the alternate routi... more The authors study the fundamental characteristics of the congestion caused by the alternate routing technique in a homogeneous computer network. They develop an approximate method for the analysis of the computer network in general environment. The model is based on the use of the input-output flow balance argument of a network node. The system behavior in the network node is characterized by the fold catastrophe. The necessary and sufficient condition that the network be congested is given by the fold point.
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Behavior characteristics of alternate routing schemes under homogeneous traffic in fully connecte... more Behavior characteristics of alternate routing schemes under homogeneous traffic in fully connected nonhierarchical networks have been investigated in the past. The fundamental behavioral characteristic of these networks has been shown to be that of a fold catastrophe. In this paper, we investigate the behavioral aspects when the traffic Intensity towards a node is much higher when compared with the traffic intensity towards other nodes. We call the high intensity traffic the concentrated traffic. In relation to the traffic intensity corresponding to the fold point under homogeneous traffic, the concentrated traffic intensity may be much higher while the intensity of traffic other than the concentrated one is much lower. For the behavioral characterization of the node under concentrated traffic, the tool of analysis employed in this paper is the same as that employed in the earlier behavioral analyses under uniform traffic: formulating the flow balance function, then obtaining the po...
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A behavioral characterization of nonhierarchical alternate routing schemes in which a certain num... more A behavioral characterization of nonhierarchical alternate routing schemes in which a certain number of trunks are reserved for direct routed traffic is presented. It is found that the fundamental behavioral characteristic of the schemes with trunk reservation control is the same as that of the schemes without reservation. A sufficient condition, which can be utilized to find the minimum number of trunks to be reserved for direct routed traffic so as to avoid the instability, obtained. Although the sufficient condition allows absolute stability of the system from the point of view of catastrophe theory, the designer may select a lower number of trunks to be reserved, provided that the stable equilibrium states remain close to each other. A performance index for comparing various levels of reservations among themselves is proposed
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Papers by Yoshikuni Onozato