研究者詳細 - 横平　徳美

論文 - 横平　徳美

分割表示 149 件中 61 - 80 件目／全件表示 >>

AS-friendly Peer Selection Algorithms without AS Topology Information in P2P Live Streaming 査読

Yukinobu Fukushima, Yin Tao, Kazuya Inada, Tokumi Yokohira

The Eighth Asia-Pacific Symposium on Information and Telecommunication Technologies (APSITT 2010) 2010年

Early Detection of Increasing Traffic with Distributed Traffic Measurement 査読

Yukinobu Fukushima, Mamoru Niboshi, Tutomu Murase, Ryohei Fujimaki, Shunsuke Hirose, Tokumi Yokohira

TENCON 2010: 2010 IEEE REGION 10 CONFERENCE 809 - 814 2010年

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）出版者・発行元：IEEE

With the spread of broadband access lines, many bandwidth-consuming services such as video streaming have appeared. The popularity of these services can cause problems such as the shortage of the Internet backbone capacity, so it is important to detect increasing traffic caused by these services early. Conventional detection method called aggregation method tries to detect increasing traffic by predicting its future traffic volume with linear approximation. However, the aggregation method may not cope with increasing traffic whose growth is more rapid than linear growth. In this paper, we propose an early detection method (partial aggregation method) of increasing traffic under per-subnet based distributed traffic measurement. The method predicts 1) future traffic volume for each address in each subnet and 2) the number of subnets having increasing traffic in the future with a linear approximation. Then, the method estimates future traffic volume for each address as a product of the predicted future traffic volume in each subnet and the predicted subnet number. As a result, the method is expected to cope with rapid growth in traffic volume. Simulation results show that the partial aggregation method can detect increasing traffic earlier than the aggregation method by a maximum of 90 days.

DOI： 10.1109/TENCON.2010.5686580

Web of Science

researchmap

Performance Evaluation of Multi-stage Change-point Detection Scheme with Alert Weighting 査読

Mari Nakagawa, Yukinobu Fukushima, Tutomu Murase, Ryohei Fujimaki, Shunsuke Hirose, Tokumi Yokohira

TENCON 2010: 2010 IEEE REGION 10 CONFERENCE 785 - 790 2010年

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）出版者・発行元：IEEE

As a detection method of large-scale simultaneous events (e.g., DDoS attack), a multi-stage change-point detection scheme with alert weighting was proposed. In the scheme, local detectors (LDs), which are deployed on each monitored subnet, try to detect an event by change-point detection. If they do, they send an alert to global detector (GD). Then GD judges whether an event is occurring by comparing the weight sum of the received alerts with an predetermined threshold value. The weight of an alert is set lower for LDs with higher false-positive rate (FPR). Conventional evaluation results only showed that alert weighting improves the performance for particular combination of two kinds of LDs with different FPRs. In this paper, we investigate the effectiveness of alert weighting for various combinations of two kinds of LDs with different FPRs in detail. We first consider the situation where detection rates (DRs) of all LDs are identical. Then, we consider the situation where high-FPR LDs show higher DR than low-FPR LDs, which is more realistic. Simulation results show that 1) alert weighting does not lead to degradation of detection performance and 2) alert weighting is most effective when event scale is moderate in our numerical examples.

DOI： 10.1109/TENCON.2010.5686586

Web of Science

researchmap

TCP-fox: A New Flow Control Method for Improving TCP Throughput in Large Bandwidth-Delay Product Networks 査読

Yuichi Nishida, Hiroyuki Ishihara, Wang Hui, Yukinobu Fukushima, Tokumi Yokohira

International Symposium on Broadband Communication (ISBC) 2010 2010年

Performance Evaluation of TCP Proxies in Network Environment Including Wireless LANs 査読

Yuichi Nishida, Wang Hui, Yukinobu Fukushima, Tokumi Yokohira

The 25th International Technical Conference on Circuits/Systems, Computers and Communications (ITC-CSCC 2010) 1231 - 1234 2010年

Performance evaluation of AS-friendly peer selection algorithms for P2P live streaming 査読

Yukinobu Fukushima, Kazuya Inada, Yin Tao, Yasuyuki Fujiwara, Tokumi Yokohira

2009 15th Asia-Pacific Conference on Communications, APCC 2009 866 - 870 2009年

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

In this paper, we evaluate the performance of peer selection algorithms: MLH (Minimum Logical Hop) and MPH (Minimum Physical Hop) to increase the number of joining peers and to decrease inter-AS traffic volume in P2P live streaming, where we assume that every peer's logical hop count (the number of providing peers between an origin streaming server and the peer) is limited by a predetermined value in order to keep real-time property of live streaming. In MLH, a newly joining peer selects such providing peers that the logical hop count is minimum to increase the number of joining peers. And then if there are several such providing peers, the newly joining peer selects such providing peers that the number (physical hop count) of ASs between the newly joining peer and each of the providing peers is minimum to decrease the inter-AS traffic volume. In MPH, a newly joining peer selects providing peers in the reverse order of MLH. Simulation results show that MLH achieves about from 20% to 60% more maximum joining peers than MPH, and MPH shows smaller inter-AS traffic volume than MLH when the number of joining peers is small while MLH shows smaller inter-AS traffic volume when the number of joining peers is large. ©2009 IEEE.

DOI： 10.1109/APCC.2009.5375467

Scopus

researchmap

A Burst Assembly Methodto Reduce End-to-End Packet Delay in Optical Burst Switching Networks 査読

Yukinobu Fukushima, Wengie Chen, Yasuyuki Fujiwara, Tokumi Yokohira

WSEAS Transactions on Communications 8 ( 8 ) 894 - 903 2009年

Dynamic splitting of light trails for increasing throughput in light trail networks 査読

Yukinobu Fukushima, Kota Tanaka, Wenjie Chen, Tokumi Yokohira

The 24th International Technical Conference on Circuits/Systems, Computers and Communications (ITC-CSCC 2009) 1370 - 1373 2009年

Throughput Improvement of TCP using Split-Connection Type Proxies in Network Environment including Wireless LANs 査読

Yuichi Nishida, Wang Hui, Hiroaki Matsumoto, Hiroyuki Ishihara, Tokumi Yokohira, Yukinobu Fukushima

The 24th International Technical Conference on Circuits/Systems, Computers and Communications (ITC-CSCC 2009 1360 - 1363 2009年

Accuracy Improvement of Multi-Stage Change-Point Detection Scheme by Weighting Alerts based on False-Positive Rate 査読

Yukinobu Fukushima, Tutomu Murase, Ryohei Fujimaki, Syunsuke Hirose, Tokumi Yokohira

CQR: 2009 IEEE INTERNATIONAL WORKSHOP TECHNICAL COMMITTEE AND COMMUNICATIONS QUALITY AND RELIABILITY 29 - + 2009年

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）出版者・発行元：IEEE

One promising approach for large-scale simultaneous events (e.g., DDoS attacks and worm epidemics) is to use a multi-stage change-point detection scheme. The scheme adopts two-stage detection. In the first stage, local detectors (LDs), which are deployed on each monitored subnet, detects a change point in a monitored metric such as outgoing traffic rate. If an LD detects a change-point, it sends an alert to global detector (GD). In the second stage, GD checks whether the proportion of LDs that send alerts simultaneously is greater than or equal to a threshold value. If so, it judges that large-scale simultaneous events are occurring. In previous studies for the multi-stage change-point detection scheme, it is assumed that weight of each alert is identical. Under this assumption, false-positive rate of the scheme tends to be high when some LDs sends false-positive alerts frequently. In this paper, we weight alerts based on false-positive rate of each LD in order to decrease false-positive rate of the multi-stage change-point detection scheme. In our scheme, GD infers false-positive rate of each LD and gives lower weight to LDs with higher false-positive rate. Simulation results show that our proposed scheme can achieve lower false-positive rate than the scheme without alert weighting under the constraint that detection rate must be 1.0.

Web of Science

researchmap

Performance Evaluation of Medium Access Control Methods in Light Trail Networks 査読

Yukinobu Fukushima, Kota Tanaka, Tokumi Yokohira

11TH INTERNATIONAL CONFERENCE ON ADVANCED COMMUNICATION TECHNOLOGY, VOLS I-III, PROCEEDINGS, 1421 - 1425 2009年

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）出版者・発行元：ELECTRONICS TELECOMMUNICATIONS RESEARCH INST

We evaluate performance of two medium access control methods with token passing, LT-FA MAC and ART MAC, in light trail networks. LT-FA MAC aims at coping with bursty packet arrivals while ART MAC aims at decreasing transmission delay. Simulation evaluation is performed in terms of the number of the maximum transmission nodes accommodated on a light trail and the maximum communication distance under the constraints that the bandwidth utilization rate of 90% and the average transmission delay of 100 ms must be achieved. Simulation results show that ART MAC permits about 500-1500km longer communication distance than LT-FA MAC with the same number of transmission nodes on a light trail and ART MAC accommodates about 15-25 more nodes than LT-FA MAC with the same communication distance.

Web of Science

researchmap

A burst assembly method to reduce end-to-end delay in optical burst switching networks

Fukushima Yukinobu, Wenjie Chen, Fujiwara Yasuyuki, Tokumi Yokohira

WSEAS Transactions on Communications 8 ( 8 ) 894 - 903 2009年

記述言語：英語掲載種別：研究論文（学術雑誌）

Although the offset-time-based scheme can differentiate loss rates of packets according to their QoS levels in optical burst switching networks, it also increases end-to-end delay of packets with higher QoS level. This is because it increases offset time of bursts in proportional to QoS levels of packets which are included in the bursts. In this paper, we propose a burst assembly method that reduces end-to-end delay. Our proposed method includes packets that arrive during the offset time into the currently assembled bursts while the conventional method includes them into the burst assembled next time. Simulation results show that our method offers 12-23% delay reduction for packets with the highest QoS level.

Scopus

researchmap

Retransmission control in TCP with a Performance Enhancing Proxy 査読

Yuichi Nishida, Wang Hui, Hiroaki Matsumoto, Tokumi Yokohira, Yukinobu Fukushima

10TH INTERNATIONAL CONFERENCE ON ADVANCED COMMUNICATION TECHNOLOGY, VOLS I-III 1881 - + 2008年

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）出版者・発行元：IEEE

In order to improve TCP performance in networks with large round trip time, a method using a PEP (Performance Enhancing Proxy) is proposed. In the method, the PEP is located on a intermediate router along a TCP connection, and returns acknowledgment packets (premature ACKs) to the source host instead of the destination host. In previous researches, although a congestion control in the PEP which keeps the number of prematurely acknowledged packets below a threshold (watermark) value has been proposed, packet losses are not taken into account, and consequently performance of the PEP under a packet-loss environment has not been investigated. In this paper, we incorporate a retransmission control to deal with packet losses into the congestion control. The proposed retransmission control mainly has two functions. One is to return duplicate premature ACKs or partial premature ACKs to urge the source host to execute the fast retransmission. The other is to retransmit prematurely acknowledged packets to the destination host, when a timeout occurs or three duplicate acknowledgments and a partial acknowledgment from the destination host are received. Simulation results under a packet-loss environment show that the PEP improves throughput larger as the end-to-end propagation delay becomes larger and throughput with PEP is a maximum of four times as much as throughput without PEP.

DOI： 10.1109/ICACT.2008.4494152

Web of Science

researchmap

Performance Evaluation of Multi-Stage Change-Point Detection Scheme against DDoS Attacks by Random Scan Worms 査読

Tutomu Murase, Yukinobu Fukushima, Masayoshi Kobayashi, Sakiko Nishimoto, Ryohei Fujimaki, Tokumi Yokohira

IEEE Communications Society Communications Quality and Reliability Workshop 2008 (CQR 2008) 2008年

Performance evaluation of a multi-stage network event detection scheme against DDoS attacks 査読

Tutornu Murase, Yukinobu Fukushima, Masayoshi Kobayashi, Hiroki Fujiwara, Ryohei Fujimaki, Tokumi Yokohira

2008 7TH ASIA-PACIFIC SYMPOSIUM ON INFORMATION AND TELECOMMUNICATION TECHNOLOGIES 58 - + 2008年

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）出版者・発行元：IEEE

Change-point detection schemes, which represent one type of anomaly detection schemes, are a promising approach for detecting network anomalies, such as attacks and epidemics by unknown viruses and worms. These events are detected as change-points. However, they generally also detect false-positive change-points caused by other events, such as hardware problems. Therefore there is a requirement for a scheme that detects only true-positive change-points caused by attacks and epidemics by unknown viruses and worms. The true-positive change-points tend to occur simultaneously and intensively in very large numbers, while the false-positive change-points tend to occur independently. We can exclude false-positive change-points by excluding those that occur independently, based on information gathered from the entire network. In this paper, we combine change-point detection schemes with a distributed IDS, and evaluate performance of the combined scheme by a simulation using the parameter values obtained by an experiment using real worms. The simulation results show that the combined scheme detects all the DDoS attacks without any false-positives while we have to tolerate false-positive rate of at least 0.02 to detect all the attacks in a stand-alone IDS scheme.

DOI： 10.1109/APSITT.2008.4653540

Web of Science

researchmap

Proposal of a hierarchical heuristic algorithm for node assignment in bidirectional manhattan street networks 査読

Masataka Yonezu, Nobuo Funabiki, Tomoya Kitani, Tokumi Yokohira, Toru Nakanishi, Teruo Higashino

Systems and Computers in Japan 38 ( 4 ) 74 - 83 2007年4月

記述言語：英語掲載種別：研究論文（学術雑誌）

In wavelength division multiplexing (WDM) technology, high-speed large-capacity communication is realized by transmitting multiple optical signals with different wavelengths in parallel on an optical fiber. In WDM technology, the logical topology of the network can generally be modified by changing the wavelength assignment to the transmitters and receivers. Thus it is important to develop an algorithm that derives the wavelength assignment that maximizes the transmission efficiency of the network. This paper considers a bidirectional Manhattan street network which has a regular topology, and proposes a hierarchical two-stage heuristic algorithm. In the first stage, the initial solution is derived by hierarchical region division and node assignment to the regions. In the second stage, the solution is improved by simulated annealing (SA). The proposed algorithm is evaluated by simulations of random instances and instances for which optimal solutions are already known. The effectiveness of the proposed algorithm is demonstrated through comparisons to the existing one. © 2007 Wiley Periodicals, Inc.

DOI： 10.1002/scj.10534

Scopus

researchmap

Detection of CMOS open node defects by frequency analysis 査読

Hiroyuki Michinishi, Tokumi Yokohira, Takuji Okamoto, Toshifumi Kobayashi, Tsutomu Hondo

IEICE TRANSACTIONS ON INFORMATION AND SYSTEMS E90D ( 3 ) 685 - 687 2007年3月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

A method to detect open node defects that cannot be detected by the conventional IDDQ test method has previously been proposed employing a sinusoidal wave superposed on the DC supply voltage. The present paper proposes a strategy to improve the detectability of the test method by means of frequency analysis of the supply current. In this strategy. defects are detected by determining whether secondary harmonics of the sinusoidal wave exist in the supply current. The effectiveness of the method is confirmed by experiments on two CMOS NAND gate packages (SSIs).

DOI： 10.1093/ietisy/e90-d.3.685

Web of Science

researchmap

Effect of premature ACK transmission timing on throughput in TCP with a performance enhancing proxy 査読

Hui Wang, Shigeyuki Osada, Tokumi Yokohira, Kiyohiko Okayama, Nariyoshi Yamai

IEICE TRANSACTIONS ON COMMUNICATIONS E90B ( 1 ) 31 - 41 2007年1月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

In order to improve TCP performance, the use of a PEP (Performance Enhancing Proxy) has been proposed. The PEP operates on a router along a TCP connection. When a data packet arrives at the PEP, it forwards the packet to the destination host, transmits the corresponding ACK (premature ACK) to the source host on behalf of the destination host, and stores a copy of the packet in a local buffer (PEP buffer) in case the packet needs to be retransmitted. In this paper, in accordance with a strategy that keeps the number of prematurely acknowledged packets in the PEP buffer below a fixed threshold (watermark) value, we investigate the relation between the watermark value and the average throughput. Extensive simulations show that the results can be roughly classified into two cases. In the first case, the average throughput becomes larger for larger watermark values and becomes a constant value when the watermark value is over a certain value. In the second case, although the average throughput becomes larger for lager watermark value in the same way, it decreases when the watermark value is over a certain value. We also show that the latter (former) case can occur more easily as the propagation delay in the input side network of the PEP becomes smaller (larger) and the propagation delay in the output side network of the PEP becomes larger (smaller), and also show that the latter (former) case can occur more easily as the transmission speed in the input side network becomes larger (smaller) and the transmission speed in the output side network becomes smaller (larger) while the PEP buffer capacity becomes smaller (larger).

DOI： 10.1093/ietcom/e90-b.1.31

Web of Science

researchmap

A Throughput Optimization Algorithm for TCP Connections with Different Routes in Long-Delay Satellite Environments 査読

Nobuto Watanabe, Wang Hui, Shigeyuki Osada, Tokumi Yokohira, Yukinobu Fukushima

The 25th AIAA International Communications Satellite Systems Conference (ICSSC 2007), Paper No. AIAA 2007-3208 in the Conference CD-ROM (12 pages) 2007年

A Wavelength and Converter Assignment Scheme for Decreasing Blocking Probability in Wavelength-Routed Networks 査読

Yukinobu Fukushima, Takahiro Ooishi, Tokumi Yokohira

The 12th OptoElectronics and Communication Conference and The 16th International Conference on Integrated Optics and Optical Fiber Communication (OECC/IOCC 2007) 454 - 455 2007年

　前のページ - 次のページ　

<横平 徳美>

論文 - 横平 徳美

<横平　徳美>

論文 - 横平　徳美