SASABE, Masahiro |
|---|
Faculty, Department/Institute
- Faculty of Informatics Department of Informatics
Academic status (qualification)
- Professor Apr. 1,2023
Academic Degrees
- Ph.D. (Information Science) Osaka University
Research Publications
Papers2022/11/29～10.1177/1748006x2211336001748-006X
Papers2022/4/25～10.1109/noms54207.2022.9789758
Papers2021/3～10.1109/tnsm.2020.3044329
Papers2021/2～10.3390/app11041617
Papers2021～
Papers2021～10.1109/JIOT.2020.3033434
Papers2021～10.1587/transcom.2021cet00010916-8516
Papers2021～10.1587/transcom.2021cep00040916-8516
Papers2020/9～10.1109/brains49436.2020.9223293
Papers2020/7/16～10.3390/ijgi9070442
PapersIn refereed2020/6/11～10.1007/s12083-020-00925-21936-6442
PapersIn refereed2020/6～10.1016/j.comnet.2020.1073831389-1286
PapersIn refereed2020/3/24～10.3390/s20061793
PapersIn refereed2020/1～10.1109/ccnc46108.2020.9045338
Papers2020～10.1109/Blockchain50366.2020.00047
Papers2020～10.1109/ojits.2020.3019935
Papers2020～
PapersIn refereed2019/12～10.1109/globecom38437.2019.9013321
PapersIn refereed2019/12～10.1109/globecom38437.2019.9014155
PapersIn refereed2019/11～10.1016/j.comcom.2019.08.0120140-3664
PapersGeographical risk analysis based path selection for automatic, speedy, and reliable evacuation guiding using evacuees’ mobile devicesIn refereedTakanori Hara, Masahiro Sasabe, Shoji KasaharaJournal of Ambient Intelligence and Humanized Computing10,6,2291-23002019/6～10.1007/s12652-018-0826-z1868-5137? 2018 Springer-Verlag GmbH Germany, part of Springer Nature It has been highly expected to achieve speedy and reliable evacuation guiding under large scale disasters. As for the speedy evacuation, an automatic evacuation guiding scheme has been proposed, which is a reactive approach based on implicit interactions among evacuees, their mobile devices, and networks. In this scheme, an evacuation route is given by the shortest path, which may not be safe. In this paper, we propose a speedy and reliable path selection based on the geographical risk map for the existing automatic evacuation guiding, which is a proactive approach that allows evacuees to evacuate speedily while avoiding encounters with blocked road segments as much as possible. First, the proposed scheme enumerates candidates of short paths from the evacuee’s current location to the refuge. Then, it selects the most reliable one from the candidates by taking into account road blockage probabilities, each of which is an estimated probability that the corresponding road is blocked under a certain disaster. Through simulation experiments, we show that the proposed scheme can improve the safety of evacuation in terms of the number of encounters with blocked road segments while keeping both the average and maximum evacuation times unchanged, compared with the shortest path selection. We further demonstrate how the proactive function, i.e., geographical risk analysis, and the reactive function, i.e., information sharing, contribute to the system performance.
Papers2019/3～
Papers2019/3～
PapersIn refereed2018/7/5～10.1016/j.comnet.2018.04.0041389-1286
PapersIn refereed2018/1/1～10.1007/s10707-016-0270-11384-6175
PapersA push strategy optimization model for a marine shrimp farming supply chain networkIn refereedLimpianchob, C, Sasabe, M, Kasahara, SInternational Journal of Operational Research1,1,1-12018～10.1504/ijor.2020.100224481745-7645
PapersRoad Network Risk Analysis Considering People Flow under Ordinal and Evacuation SituationsIn refereedSasabe, M, Fujii, K, Kasahara, SEnvironment and Planning B: Urban Analytics and City Science47,5,759-7742018～10.1177/23998083188029402399-8083Both pre-disaster approaches, e.g., mitigation and preparedness, and post-disaster approaches, e.g., response and recovery, play important roles to mitigate the damage from large-scale disasters. From the viewpoint of disaster response, there have been studies on evacuation guiding schemes and applications using evacuees’ mobile devices, e.g., smart phones. On the other hand, disaster preparedness has also been studied mainly on geographical information analysis, e.g., road blockage probability and people flow data. The road blockage probability is the probability that the corresponding road is blocked due to collapse of roadside buildings when an earthquake occurs. The people flow data express the people flow in usual time. In this paper, with the help of evacuation guiding schemes, road blockage probability, and people flow data, we propose a road network risk analysis approach that considers people flow in both ordinary and evacuation situations, which can be used to as a tool to strengthen the urban fabric for fostering better evacuees’ responses in disaster situations. First, the proposed approach derives ordinary road demand, which is the degree of road usage at a certain interval in an ordinary situation, from the people flow data. Then, it calculates evacuation road demand, i.e., the degree of road usage at a certain interval in an evacuation situation, by extending the edge betweenness centrality under the assumption that people located according to the ordinary road demand move to refuges along their evacuation paths. Finally, it detects roads with high risk of encountering blocked road segments by combining the road blockage probability and evacuation road demand. Through numerical experiments under a case study of Arako area of Nagoya city in Japan, we show the proposed approach can detect such high-risk roads. Furthermore, we show the detected roads spatially change according to the people flow in ordinary situations, evacuation behavior, and disaster occurrence time.
PapersIn refereed2017/12/15～10.1109/ATNAC.2017.8215373
PapersIn refereed2017/12/1～10.1186/s13638-017-0948-61687-1499
PapersOn collaborative spectrum sensing mechanism based on system load and detection performance in cognitive radio networks117,204,61-662017/9/7～0913-5685
PapersTransmission opportunity based group formation of secondary users for collaborative spectrum sensing in cognitive radio networks with multiple primary users116,484,499-5042017/3/2～0913-5685
PapersOn Path Selection Considering Length and Reliability for Automatic Evacuation Guiding Based on Interactions between Evacuees and Their Mobile Nodes116,484,517-5222017/3/2～0913-5685
PapersAn Offline Mobile Application for Automatic Evacuation GuidingIn refereedItoi, J, Sasabe, M, Kawahara, J, Kasahara, SScientific Phone Apps and Mobile Devices3:1,,-2017/1～10.1186/s41070-017-0013-1
PapersIn refereed2017～10.1007/978-3-319-65515-4_31611-3349
PapersAutomatic evacuation guiding scheme based on implicit interactions between evacuees and their mobile nodesKomatsu Nobuhisa, Sasabe Masahiro, Kawahara Jun, Kasahara Shoji,,-2016/8/30～1573-7624
PapersOn Congestion-Aware Route Selection for Automatic Evacuation Guiding Based on Cooperation between Evacuees and Their Mobile Nodes116,161,1-62016/7/26～0913-5685
PapersEvaluation of influence of a mobility model based on person trip data on DTN routing115,496,13-182016/3/7～0913-5685
PapersOn Information Sharing Scheme for Automatic Evacuation Guiding System Based on Cooperation between Evacuees and Their Mobile Nodes115,496,7-122016/3/7～0913-5685
PapersDesign, implementation, and evaluation of an offline evacuation guiding application considering positioning errors of mobile nodes115,496,1-62016/3/7～0913-5685
PapersDistributed Cooperative Control for Speedy and Effective Coverage in Mobile Sensor Networks115,408,79-842016/1/21～0913-5685
PapersIn refereed2016～10.1109/APCC.2016.75814362163-0771
PapersOn Information Sharing Scheme for Automatic Evacuation Guiding System Using Evacuees' Mobile NodesIn refereedNobuhisa Komatsu, Masahiro Sasabe, Shoji KasaharaMOBILE WEB AND INTELLIGENT INFORMATION SYSTEMS, (MOBIWIS 2016)9847,,213-2212016～10.1007/978-3-319-44215-0_170302-9743We have proposed an automatic evacuation guiding scheme based on cooperation between evacuees and their mobile nodes. In the previous work, we assume that information about blocked road segments is shared among mobile nodes through Epidemic routing, which is a Delay Tolerant Network (DTN) routing protocol. In this paper, we propose an information sharing scheme called On-Demand Direct Delivery, which can reduce the network load compared to Epidemic routing. Since each evacuee moves to a safe place, he/she will require the information about blocked road segments in the region from the current position to the safe place. The proposed scheme selectively retrieves the information about blocked road segments in that region, through Direct Delivery. Through simulation experiments, we show the proposed scheme can keep the effectiveness of evacuation guiding with reduction of network load to about 1/36, compared to Epidemic routing.
PapersB-15-8 Design of an evacuation guiding application based on cooperation between an evacuee and a mobile nodeItoi Junki, Sasabe Masahiro, Kawahara Jun, Kasahara ShojiProceedings of the Society Conference of IEICE2015,1,391-3912015/8/25～
PapersPath Enumeration Algorithm Using Zero-Suppressed Binary Decision Diagram for Path Selection in Overlay Networks115,130,51-542015/7/6～0913-5685
PapersPoster : On Controllable Tit-for-Tat-Based P2P File Distribution115,130,33-382015/7/6～0913-5685
PapersSelf-Organizing Resource Allocation Scheme Using Evolutionary Game Theoretic Approach for Large-Scale Distributed SystemsYAMAGIWA Shingo, SASABE Masahiro, TAKINE TetsuyaIEICE technical report114,477,529-5342015/3/2～0913-5685Large distributed systems, such as peer-to-peer networks and wireless sensor networks, provide users with multiple services by using lots of computational resources. Because such resources are limited, it is important to allocate them dynamically in response to users' demands. Centralized resource allocation schemes, however, have a potential drawback of scalability. In this paper, we propose a decentralized resource allocation scheme, where agents, which are running on the computational resources, autonomously determine services to provide. Specifically, we apply evolutionary game theory to achieve self-organizing resource allocation. Through analysis and simulation experiments, we show the effectiveness of the proposed scheme in terms of convergence accuracy, spatial distribution of service share, and stability.
PapersVisiting Order Considering Proximity between Clusters in Ferry-Assisted DTNsIZUMI Yoshiaki, SASABE Masahiro, TAKINE TetsuyaIEICE technical report114,477,523-5282015/3/2～0913-5685Recently, it is required to construct inexpensive communication infrastructures in rural areas and emergency networks in disaster areas. In such environments, there are multiple isolated clusters, such as villages in rural areas or emergency shelters in disaster areas. In this paper, we focus on ferry-assisted DTNs in which a special mobile node called a message ferry visits clusters to support communication with external networks through a special cluster, called a base cluster, which has access links. In the ferry assisted DTNs, visiting order of the message ferry determines the mean delivery delay of data (bundles), which is the average time interval from the generation of a bundle in a cluster to the completion of its delivery to the base cluster. In this paper, we propose a hybrid visiting order method that combines the two types of existing visiting order in consideration of the proximity between clusters. Through simulation experiments, we evaluate the effectiveness of the proposed method in terms of the average delivery delay.
PapersMonitoring Control Using Optimal Stopping Rule in Mobile Sensor NetworksWATANABE Kazuma, SASABE Masahiro, TAKINE TetsuyaIEICE technical report114,477,577-5822015/3/2～0913-5685In recent years, there have been many studies on monitoring in mobile sensor networks, e.g., disaster prevention, crime prevention, environmental monitoring, and ecosystem monitoring. Because mobile sensors are usually powered by batteries, it is important to achieve monitoring with low power consumption. In this paper, we propose a monitoring scheme composed of two phases: search phase and observation phase. In the search phase, mobile sensors aim to discover important places speedily. After that, they continue to observe the important places in the observation phase. Under the assumption that importance values of places in a monitoring area are inde- pendent and identically distributed according to a uniform distribution, we formulate the optimal phase transition to be an optimal stopping problem and derive the optimal phase transition rule. Through both the numerical and simulation experiments, we show the effectiveness of the proposed scheme.
PapersOverlay Multicast with Peak Traffic Constraints for Inter-Data Center CommunicationKANEKO Motoki, SASABE Masahiro, TAKINE TetsuyaIEICE technical report114,477,161-1662015/3/2～0913-5685Recently, service providers have been using data centers (DCs) to provide cloud services. When they use multiple DCs, which are geographically distributed, they require communication for maintenance operations among them, e.g., synchronization and update. Because such maintenance operations need to send identical data from one source to multiple destinations, we apply overlay multicast. Note that main traffic yielded by cloud services temporally changes and the charge for access links is determined by their peak traffic. In this paper, we aim to maximize the amount of overlay multicast traffic under the constraint of the peak traffic. We first formulate our problem as a linear programming. We further propose a scheme for estimating the peak traffic. Through simulation experiments, we show the effectiveness of the proposed method in terms of the amount of overlay multicast traffic and peak traffic.
PapersBI-4-5 Unconscious cooperation based control of P2P file distributionSasabe MasahiroProceedings of the IEICE General Conference2015,2,"SS-78"-"SS-79"2015/2/24～
PapersBS-8-2 On detection of outlier trajectories in evacuation guiding system using trajectories of mobile terminalsOtsuki Kohei, Kawahara Jun, Sasabe Masahiro, Kasahara ShojiProceedings of the IEICE General Conference2015,2,"S-156"-"S-157"2015/2/24～
PapersProposal and Evaluation of Evacuation Guiding Scheme Using Trajectories of Mobile TerminalsKOMATSU Nobuhisa, SASABE Masahiro, KAWAHARA Jun, KASAHARA ShojiTechnical report of IEICE. CQ114,404,101-1062015/1/22～0913-5685When large-scale disasters occur, evacuees have to evacuate to safe places quickly. In this paper, we propose an evacuation guiding scheme using mobile terminals of evacuees. Each terminal tries to navigate its evacuee by presenting an evacuation route. It can also trace the actual evacuation route of the evacuee as the trajectory by measuring his/her positions periodically. The proposed scheme automatically estimates blocked road segments from the difference between the presented evacuation route and actual evacuation route, then recalculates the alternative evacuation route. In addition, evacuees also share such information among them through communication with other mobile terminals and that with a server via communication infrastructures. Through simulation experiments, we evaluate fundamental characteristics of the proposed scheme, impact of degree of disaster, and effect of information sharing.
PapersIn refereed2015～10.1007/978-3-319-23144-0_10302-9743
PapersIn refereed2015～10.1109/ICOIN.2015.70578811976-7684
PapersIn refereed2014/12～10.1587/transcom.E97.B.26500916-8516
PapersDistributed cooperative control for speedy coverage in mobile sensor networksWATANABE Kazuma, SASABE Masahiro, TAKINE TetsuyaTechnical report of IEICE. CQ114,131,45-502014/7/10～0913-5685In recent years, mobile sensor networks have been expected to realize environmental monitoring and ecosystem monitoring. It is desirable that mobile sensors autonomously cooperate with each other in a distributed manner such that they can cover important locations in the target area. Game theoretical approaches have been attracting many researchers to achieve such distributed cooperative control. In the game theoretical approaches, we need to design a game model and a learning algorithm. The game model should be designed to enhance the accuracy of coverage in steady state. The learning algorithm should be designed to lead the system to appropriate steady states, independent of initial states. In this paper, we propose a learning algorithm where mobile sensors efficiently explore the area by sharing their search histories and speedily move to their appropriate locations. Through simulation experiments, we demonstrate that the proposed algorithm can achieve high accuracy of coverage even when each mobile sensor explores a limited range of the entire area.
Papers2014/7～
PapersAnalysis of Optimal Scheduling in Tit-for-Tat-based P2P File DistributionHASEGAWA Masashi, SASABE Masahiro, TAKINE TetsuyaIEICE technical report113,472,167-1722014/3/6～0913-5685Peer-to-Peer (P2P) file distribution systems can efficiently disseminate massive contents, such as disk images of operating systems, to many users in a piece-by-piece manner. In particular, BitTorrent protocol optimizes each peer's download speed by applying tit-for-tat (TFT) strategy, where each peer preferentially uploads piece(s) to peer(s) from which it can download missing pieces faster. To the best of our knowledge, however, it has not been sufficiently studied on the optimality of such TFT-based P2P file distribution. In this paper, we aim to figure out the optimal scheduling in the TFT-based P2P file distribution. First, we formulate the scheduling in TFT-based P2P file distribution as a integer linear programming, where the variables are piece transfers between peers at each time and the objective function is the minimization of the average file retrieving time among peers. Through the analysis of the optimal solution obtained by the existing solver, we reveal the characteristics of the optimal scheduling.
PapersDS-2-2 Network Environment Adaptive Store-Carry-Forward RoutingKimura Tomotaka, Matsuura Tsubasa, Sasabe Masahiro, Matsuda Takahiro, Takine TetsuyaProceedings of the IEICE General Conference2014,1,"S-24"-"S-25"2014/3/4～1349-144X
PapersIn refereed2014～10.1155/2014/7190291537-744X
PapersIn refereed2014～10.1155/2014/7190291537-744X
PapersIn refereed2013/4～10.1109/JSAC.2013.1304140733-8716
PapersTree-Set Selection for High-Speed Multicast in Overlay Networks with Linear Capacity ConstraintsMIZUGUCHI Hiroaki, SASABE Masahiro, TAKINE TetsuyaIEICE technical report. Information networks112,393,51-562013/1/24～0913-5685Because overlay networks for inter-data center communication are composed of reliable nodes, high-speed overlay multicast is expected to be realized using the information about the underlying IP networks. In this paper, we aim to achieve the high-speed multicast based on multiple trees by taking account of the IP-level interference between them. We first formulate the tree-set selection problem for high-speed multicast in overlay networks with linear capacity constraints. We further propose a space-efficient heuristic algorithm to solve this problem. Through numerical results, we show that the heuristic algorithm can obtain quasi-optimal tree set.
PapersIn refereed2013～10.1587/transcom.E96.B.20761745-1345
PapersIn refereed2013～10.1155/2013/1874791537-744X
PapersGrouping clusters to minimize the total mean delivery delay of bundles in ferry-assisted DTNsKABIRI K. Habibul, SASABE Masahiro, TAKINE Tetsuya電子情報通信学会技術研究報告. NS, ネットワークシステム111,408,87-922012/1/19～0913-5685Communication among isolated networks (clusters) in delay tolerant networks (DTNs) can be supported by a message ferry, which collects bundles from clusters and delivers them to a sink node. When there are lots of distant static clusters, multiple message ferries and sink nodes will be required. In this paper, we aim to make groups each of which consists of physically close clusters, a sink node, and a message ferry. Our main objective is minimizing the overall mean delivery delay of bundles in consideration of both offered load of clusters and distance between clusters and their sink nodes. We first model this problem as a nonlinear integer programming, based on the knowledge obtained in our previous work. Because it might be hard to solve this problem directly, we take two-step optimization approach based on linear integer programming, which yields an approximate solution of the problem. Through numerical results, we show the two-step optimization approach works well.
PapersIn refereed2012～10.4304/jcm.7.10.749-7571796-2021
PapersIn refereed2012～10.1007/978-3-642-32615-8_271867-8211
PapersIn refereed2012～10.1109/WAINA.2012.160
PapersIn refereed2011/11～10.3934/naco.2011.1.5632155-3289
PapersEvaluation of user behavior and system availability based on measurement of BitTorrentGODA Shin, SASABE Masahiro, TAKINE TetsuyaIEICE technical report110,116,85-902010/7/8～0913-5685Each user in the Peer-to-Peer (P2P) file-sharing systems potentially tends to maximize its own benefit rather than the overall system efficiency and performance. On the other hand, there are lots of indistinct points left in the users' selfish behavior and its influence on the system performance. In this paper, we measure the BitTorrent system, which is one of the most famous P2P file-sharing systems, and evaluate users' behavior and system availability. The measurement is conducted through communications with a tracker which manages information about peers sharing the files and with each of those peers. The measurement result shows that about half of users stop opening the file to the public within several hours after completing the file retrieval. In addition, we show that the system is supported not only by a few peers that remain to be providers of the file for a long term, but also by most peers that are temporal suppliers during their own file retrieval.
PapersIn refereed2010/3～10.1007/s12083-009-0045-71936-6442
PapersIn refereed2010/3～10.1587/transcom.E93.B.4900916-8516
PapersIn refereed2010/1～10.1587/transcom.E93.B.990916-8516
PapersIn refereed2010～10.1155/2010/3698141687-7578
PapersSimulation-Based Evaluation of P2P File-Sharing Systems underHeterogeneous Environments: Evolutionary Game Theoretic ApproachIn refereedYusuke Matsuda, Masahiro Sasabe, Tetsuya TakineProceedings of the 2009 International Symposium on Nonlinear Theory and its Applications (NOLTA'09),,-2009/10～
PapersReal-Time Measurement of Frequently Distributed Files in P2P File-Sharing SystemsMATSUMORI Tomoya, SASABE Masahiro, TAKINE TetsuyaIEICE technical report109,79,5-102009/6/4～0913-5685Since files are directly exchanged between nodes in P2P file-sharing systems such as Winny and Bittorrent, it is difficult to comprehensively grasp the system conditions and control the system dynamics. In this paper, we design and implement a system that can achieve real-time measurement of files which are highly interested and frequently distributed over the Winny network. We introduce a node for the measurement into the Winny network and passively measure queries passing through the node with low measurement overhead and high adaptability to the changes of network conditions. To achieve the real-time measurement, we combine the sliding window method and frequent pattern mining. The experimental results show that we can clearly reveal the transition of frequently distributed files in real-time.
PapersLoad-balanced and interference-aware spanning tree construction algorithm for TDMA-based wireless mesh networksTOKITO Hiroshi, SASABE Masahiro, HASEGAWA Go, NAKANO HirotakaIEICE technical report108,481,1-62009/3/5～0913-5685Wireless mesh networks have been attracting many users in recent years. By connecting base stations (mesh nodes) with each other via wireless connections, they can achieve a wide-area wireless environment with flexible-configuration and low-cost properties at the risk of radio interference between wireless links. When we utilize the wireless mesh networks as an infrastructure for Internet access, all network traffic from mobile nodes goes through a gateway node which is directly connected to the wired network. Therefore, we need to distribute the traffic load by deploying multiple gateway nodes. In this paper, we propose a spanning tree construction algorithm for TDMA-based wireless mesh networks with multiple gateway nodes, which aims to maximize the traffic going to wired network (system throughput) by taking account of the traffic load on the gateway nodes, the access link capacity and the radio interference. Through simulation experiments, we show that the proposed algorithm increases the system throughput regardless of the bottleneck position and achieves up to 3.1 times higher system throughput than the conventional algorithm.
PapersPower control methods considering radio interference and path length for wireless mesh networksHIDEKUMA Toshiaki, HASEGAWA Go, SASABE Masahiro, NAKANO HirotakaIEICE technical report108,481,7-122009/3/5～0913-5685Wireless Mesh Networks (WMNs) have attracted significant interest as a cost-effective wireless network infrastructure. However, the efficiency of wireless resource utilization decreases by radio interference when multiple transmissions in an interference region occur simultaneously. One of possible solutions for this problem is to control the transmission power of mesh nodes. In this report, we propose a power control method of wireless mesh nodes for increasing spatial reuse in WMNs with TDMA MAC protocol. The proposed method decreases radio interference, considering the ill-effect of the increase in path length by cutting too many wireless links. Numerical evaluation results reveal that the proposed method decreases the frame length by up to 27% with non-sensitive parameter setting.
PapersIn refereed2009～10.1109/WOWMOM.2009.5282459
PapersIn refereed2009～10.1109/ICN.2009.21
PapersIn refereed2009～10.1109/ICN.2009.22
PapersIn refereed2009～10.1109/INCOS.2009.20
PapersIn refereed2008/12～10.1093/ietcom/e91-b.12.38510916-8516
PapersHow Does User Heterogeneity Affect Performance of P2P Caching?: Evolutionary Game Theoretic ApproachIn refereedMasahiro Sasabe, Yusuke Matsuda, Tetsuya TakineProc. of 1st International Workshop on Technologies for Ambient Information Society (TAIS 2008),,-2008/11～
PapersA Study on Performance Evaluation of P2P File Sharing under Heterogeneous User Environments : Evolutionary Game Theoretic ApproachMATSUDA Yusuke, SASABE Masahiro, TAKINE TetsuyaIEICE technical report108,203,51-562008/9/4～0913-5685In Peer-to-Peer (P2P) file sharing systems, file availability is improved by users cooperatively caching and sharing files. However, many users may hesitate to cache files cooperatively due to the cost for caching, such as storage consumption, processing load, and bandwidth consumption. In such a case, unpopular files are likely to disappear from the system. In this paper, we reveal how the selfish user behavior affects the system performance using evolutionary game theoretic approach. Specifically, we focus on situations where users are heterogeneous in terms of aggressiveness in cooperative caching. Analytical results show that the user heterogeneity contributes to the stability of file availability.
PapersA Study on Performance Evaluation of P2P File Sharing under Heterogeneous User Environments: Evolutionary Game Theoretic ApproachYusuke Matsuda, Masahiro Sasabe, Tetsuya TakineIEICE technical report108,203,51-562008/9～0913-5685In Peer-to-Peer (P2P) file sharing systems, file availability is improved by users cooperatively caching and sharing files. However, many users may hesitate to cache files cooperatively due to the cost for caching, such as storage consumption, processing load, and bandwidth consumption. In such a case, unpopular files are likely to disappear from the system. In this paper, we reveal how the selfish user behavior affects the system performance using evolutionary game theoretic approach. Specifically, we focus on situations where users are heterogeneous in terms of aggressiveness in cooperative caching. Analytical results show that the user heterogeneity contributes to the stability of file availability.
PapersPower control method for increasing capacity in wireless mesh networksIEICE technical report108,151,61-662008/7/24～0913-5685
PapersTracking moving objects across multiple regions by successive bayesian estimationWATANABE Takafumi, SASABE Masahiro, NAKANO HirotakaIEICE technical report107,524,353-3582008/2/28～0913-5685In this paper, we focus on tracking moving objects in a building using a binary-sensor network. In buildings, there are multiple points where objects temporarily change their velocities, such as doors and stairs. We call these points as gates. We assume that the velocity of an object does not almost change before and after passing a gate. We first divide the entire area in a building into multiple sub-regions each of which has gates as their entrances. To track objects in a sub-region, we apply the conventional method based on a Bayesian estimation. The conventional method conducts object tracking using statistically obtained information on object velocities. We expect that we can improve accuracy of object tracking by proposing a method to share the velocity information among sub-regions. Through simulation experiments, we demonstrate that the accuracy of object tracking has a maximum of 35% improvements compared with the conventional method.
PapersImproving Success Ratio of Object Search in Highly-Dynamic Mobile P2P NetworksTAKESHITA Kei, SASABE Masahiro, NAKANO HirotakaIEICE technical report107,445,1-62008/1/17～0913-5685With the wide spread of mobile devices, information discovery methods over mobile ad hoc networks (MANETs) are required. Recent studies have revealed that integrating a distributed hash table (DHT) substrate and network-layer routing can increase search efficiency. Furthermore, some researchers have additionally proposed a clustering method which groups the overlay nodes according to their physical distance. However, it has also been pointed out that the search efficiency deteriorates in highly dynamic environments. In this paper, we propose a method sharing pointers among nodes in a cluster. Through simulation experiments, we show that the proposed method improves the success ratio of object search up to 40% compared with existing method.
PapersIn refereed2008～10.1109/PERCOM.2008.382474-2503
PapersIn refereed2007/12～10.1109/JSYST.2007.9076811932-8184
PapersRapid Readout of Multiple RFIDs by Response Probability Control MethodNAKANO Hirotaka, NAGATE Wataru, HIRANO Yusuke, SASABE MasahiroThe IEICE transactions on electronics C90,6,491-5012007/6/1～1345-2827
Papers2007/4/16～
PapersImprovement of the Capacity of Wireless Networks by Optimizing Communication DistanceTOKITO Hiroshi, SASABE Masahiro, NAKANO HirotakaIEICE technical report106,578,95-1002007/3/1～0913-5685As the number of nodes increases, the capacity of ad-hoc wireless networks is constrained by radio interference. Especially, when a source node cannot directly communicate with its destination node, every packet has to travel through one or more relay nodes. The throughput decreases as the number of relayed hop count increases. To effectively use the limited radio resources, we propose a scheme that a node avoids radio interference among its adjacent nodes by appropriately controlling its transmission power. In this case, the capacity is expected to quite improve when each node sets distance to physical distance to the next hop. However, this may be difficult to realize in practical environments. In this paper, through analysis and simulation experiments, we examine the optimal communication distance to maximize the network capacity when all nodes take the same communication distance. Results showed that the communication distance to maximize the network capacity depends on the node density. We further showed that the network capacity is independent of the node density. In addition, the proposed scheme could improve the network capacity up to 2.1 times higher than the traditional scheme.
PapersCaching Algorithms using Evolutionary Game Theory in a File-Sharing SystemSASABE Masahiro, WAKAMIYA Naoki, MURATA MasayukiIEICE technical report106,461,97-1022007/1/11～0913-5685In a P2P file-sharing system, a node finds and retrieves its desired file. If multiple nodes cache the same file to provide others, we can achieve a file-sharing system with low latency and high file availability. However, a node has to spend costs, e.g., processing load or storage capacity, on caching of a file. Consequently, a node may selfishly behave and hesitate to cache a file. In such a case, there is a possibility that unpopular files disappear from the system. In this paper, we aim to accomplish effective caching in the whole system that emerges from autonomous and selfish node behaviors. We first discuss relationship between selfish node behaviors and system dynamics according to evolutionary game theory. As a result, we show that a file-sharing system can be robust to file disappearance depending on a model of cost and demand for caching even if nodes behave selfishly.
PapersCaching Algorithms using Evolutionary Game Theory in a File-Sharing SystemSASABE Masahiro, WAKAMIYA Naoki, MURATA MasayukiIEICE technical report106,461,97-1022007/1/11～0913-5685In a P2P file-sharing system, a node finds and retrieves its desired file. If multiple nodes cache the same file to provide others, we can achieve a file-sharing system with low latency and high file availability. However, a node has to spend costs, e.g., processing load or storage capacity, on caching of a file. Consequently, a node may selfishly behave and hesitate to cache a file. In such a case, there is a possibility that unpopular files disappear from the system. In this paper, we aim to accomplish effective caching in the whole system that emerges from autonomous and selfish node behaviors. We first discuss relationship between selfish node behaviors and system dynamics according to evolutionary game theory. As a result, we show that a file-sharing system can be robust to file disappearance depending on a model of cost and demand for caching even if nodes behave selfishly.
PapersMobility model based on incoming and outgoing nodes to an areaIn refereedS. Aihara, M. Sasabe, H. NakanoInternational Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences - ISPRS Archives36,,-2007/1/1～1682-1750? 2007 International Society for Photogrammetry and Remote Sensing. All rights reserved. In this paper, we propose a mobility model which estimates a node distribution in a service area from node flows on the boundary of the area. Our model targets new wireless communication techniques, such as Bluetooth and ZigBee, whose transmission ranges, called cells, are relatively small. The proposed model reproduces the mobility of nodes in an area by the observation of the incoming and outgoing nodes to the area. At first, we focus on a person as a node and observe an area where people actually pass through. From the observation results, we show that a node moves along with an approximately straight line with a velocity following a normal distribution. Furthermore, we propose two methods that estimate correspondences between incoming and outgoing events to the area; combinatorial optimization based method (COM) and Bayesian estimation based method (BEM). As a result, the reproduction ratio of COM is 0.736, and that of BEM is 1.
PapersIn refereed2007～10.1109/ICMWCN.2007.4668171
PapersIn refereed2007～
PapersIn refereed2007～10.1109/ISCC.2007.43816271530-1346
PapersA Construction Method of a Low-Diameter, Location-Aware, and Resilient P2P NetworkSASABE Masahiro, WAKAMIYA Naoki, MURATA MasayukiIEICE technical report105,628,131-1362006/3/2～0913-5685Since a peer searches for its desired file in a P2P file sharing system, the structure of an overlay network determines the effectiveness of search in terms of network load and search latency. In this paper, based on the Barabasi-Albert (BA) model, we propose a novel method to construct a low-diameter and location-aware overlay network where peers can find physically-close providers without introducing much load on underlying physical networks. We also propose a rewiring method to improve the structure of the overlay network and a recovery method to cope with random peer departures and malicious attacks. Through several simulation experiments using real physical topologies, we found that the proposed methods could construct a resilient overlay network that improved reachability up to 60% compared with BA model while shortening physical distance from neighboring peers.
PapersIn refereed2006～10.1117/12.6857910277-786X
PapersIn refereed2006～10.1117/12.6856660277-786X
PapersIn refereed2006～10.1109/COLCOM.2006.361863
PapersIn refereed2005/7～1109-2742
PapersIn refereed2004/12～
PapersIn refereed2004/11～10.1002/ett.10141124-318X
PapersSB-10-2 Cache Replacement Algorithm for P2P Media Streaming(SB-10. Latest Trends on Broadband Contents Delivery Technologies)SASABE Masahiro, WAKAMIYA Naoki, MURATA Masayuki, MIYAHARA HideoProceedings of the IEICE General Conference2004,2,"SE-3"-"SE-4"2004/3/8～
PapersThird International Conference on Peer-to-Peer Computing (P2P 2003)In refereedSASABE MasahiroSystems, control and information48,2,75-752004/2/15～0916-1600
PapersIn refereed2004～0302-9743
PapersScalable Methods for Media Streaming on Peer-to-Peer NetworksSASABE Masahiro, WAKAMIYA Naoki, MURATA Masayuki, MIYAHARA HideoIEICE technical report. Communication systems103,313,71-762003/9/18～0913-5685With the growth of computing power and the proliferation of broadband access to the Internet, media streaming has widely diffused. By using the P2P communication architecture, media streaming can be expected to smoothly react to network conditions and changes in user demands for media-streams. In this paper, we propose efficient methods to achieve continuous and scalable media streaming system. In our mechanisms, a media stream is divided into blocks for efficient use of network bandwidth and storage space. We propose scalable search methods, algorithms to determine an optimum provider peer from search results, and a caching algorithm considering on the balance between supply and demand for media streams. Through several simulation experiments, it was shown that proposed mechanisms could accomplish continuous media streaming without deteriorating the system scalability.
PapersScalable Methods for Media Streaming on Peer-to-Peer NetworksSASABE Masahiro, WAKAMIYA Naoki, MURATA Masayuki, MIYAHARA HideoIEICE technical report103,309,71-762003/9/18～0913-5685With the growth of computing power and the proliferation of broadband access to the Internet, media streaming has widely diffused. By using the P2P communication architecture, media streaming can be expected to smoothly react to network conditions and changes in user demands for media-streams. In this paper, we propose efficient methods to achieve continuous and scalable media streaming system. In our mechanisms, a media stream is divided into blocks for efficient use of network bandwidth and storage space. We propose scalable search methods, algorithms to determine an optimum provider peer from search results, and a caching algorithm considering on the balance between supply and demand for media streams. Through several simulation experiments, it was shown that proposed mechanisms could accomplish continuous media streaming without deteriorating the system scalability.
PapersScalable Methods for Media Streaming on Peer-to-Peer NetworksSASABE Masahiro, WAKAMIYA Naoki, MURATA Masayuki, MIYAHARA HideoIEICE technical report. Information networks103,311,71-762003/9/18～0913-5685With the growth of computing power and the proliferation of broadband access to the Internet, media streaming has widely diffused. By using the P2P communication architecture, media streaming can be expected to smoothly react to network conditions and changes in user demands for media-streams. In this paper, we propose efficient methods to achieve continuous and scalable media streaming system. In our mechanisms, a media stream is divided into blocks for efficient use of network bandwidth and storage space. We propose scalable search methods, algorithms to determine an optimum provider peer from search results, and a caching algorithm considering on the balance between supply and demand for media streams. Through several simulation experiments, it was shown that proposed mechanisms could accomplish continuous media streaming without deteriorating the system scalability.
PapersProxy Caching Mechanisms with Quality Adjustment for Video Streaming ServicesIn refereedMasahiro Sasabe, Yoshiaki Taniguchi, Naoki Wakamiya, Masayuki Murata, Hideo MiyaharaIEICE Transactions on CommunicationsE86-B,,1849-18582003/1/1～The proxy mechanism widely used in WWW systems offers low-delay data delivery by means of "proxy server." By applying proxy mechanisms to video streaming system, we expect that high-quality and low-delay video distribution can be accomplished without introducing extra load on the system. In addition, it is effective to adapt the quality of cached video data appropriately in the proxy if user requests are diverse due to heterogeneity in terms of the available bandwidth, end-system performance, and user's preferences on the perceived video quality. In this paper, we propose proxy caching mechanisms to accomplish high-quality and low-delay video streaming services, In our proposed system, a video stream is divided into blocks for efficient use of cache buffer. A proxy cache server is assumed to be able to adjust the quality of cached or retrieved video blocks to requests through video filters. We evaluate our proposed mechanisms in terms of the required buffer size, the play-out delay and the video quality through simulation experiments. Furthermore, to verify the practicality of our mechanisms, we implement our proposed mechanisms on a real system and conducted experiments. Through evaluations from several performance aspects, it is shown that our proposed mechanisms can provide users with a low-latency and high-quality video streaming service in a heterogeneous environment.
PapersIn refereed2003～10.1109/PTP.2003.1231508
PapersImplementation and Evaluation of Proxy Caching Mechanisms with Video Quality AdjustmentTANIGUCHI Yoshiaki, SASABE Masahiro, WAKAMIYA Naoki, MURATA Masayuki, MIYAHARA HideoTechnical report of IEICE. CQ102,191,41-462002/7/5～0913-5685The proxy mechanism widely used in WWW systems offers low-delay data delivery by means of "proxy server". By applying proxy mechanisms to the video streaming system, we expect that high-quality and low-delay video distribution can be accomplished without introducing extra load on a system. In addition, it is effective for proxy to adapt the quality of cached video data to users requests if requests are diverse due to heterogeneity in terms of the available bandwidth, end-system performance, and user's preferences on the perceived video quality. We have proposed proxy caching mechanisms to accomplish the high-quality and highly-interactive video streaming services. In our proposed system, a video stream is divided into blocks for efficient use of a cache buffer. A proxy server is assumed to be able to adjust the quality of a cached or retrieved video block to a request through video filters. In this paper, to verify the practicality of our mechanisms, we implemented them on a real system and conducted experiments. Through evaluations from several performance aspects, it was shown that our proposed mechanisms can provide users with a video streaming service in a heterogeneous environment.
PapersImplementation and Evaluation of Proxy Caching Mechanisms with Video Quality AdjustmentTANIGUCHI Yoshiaki, SASABE Masahiro, WAKAMIYA Naoki, MURATA Masayuki, MIYAHARA HideoITE Technical Report26,0,41-462002～10.11485/itetr.26.48.0_411342-6893The proxy mechanism widely used in WWW systems offers low-delay data delivery by means of "proxy server". By applying proxy mechanisms to the video streaming system, we expect that high-quality and low-delay video distribution can be accomplished without introducing extra load on a system. In addition, it is effective for proxy to adapt the quality of cached video data to users requests if requests are diverse due to heterogeneity in terms of the available bandwidth, end-system performance, and user's preferences on the perceived video quality. We have proposed proxy caching mechanisms to accomplish the high-quality and highly-interactive video streaming services. In our proposed system, a video stream is divided into blocks for efficient use of a cache buffer. A proxy server is assumed to be able to adjust the quality of a cached or retrieved video block to a request through video filters. In this paper, to verify the practicality of our mechanisms, we implemented them on a real system and conducted experiments. Through evaluations from several performance aspects, it was shown that our proposed mechanisms can provide users with a video streaming service in a heterogeneous environment.
PapersCaching mechanisms for proxy cache with quality adaptationSASABE Masahiro, WAKAMIYA Naoki, MURATA Masayuki, MIYAHARA HideoIEICE technical report101,121,31-362001/6/22～0913-5685The proxy mechanism is now widely used in WWW system in order to offer low-delay data delivery with an assistance of the "proxy server". By applying the proxy mechanism to video transfer, we can expect a low-delay and interactive video streaming service provided without intoroducing extra load on the stream. In addition, if the proxy appropriately adapts the quality of cached video data to the requested quality, video streams can be delivered to users by considering their heterogeneous QoS requirements. In this paper, we consider mechanisms of data retrieval, prefetching and replacement for the proxy cache. Through simulation experiments, we show that our proposed proxy caching mechanism achieves a high-quality and low-delay video distribution which meeting user's demand.
PapersIn refereed2001～10.1117/12.4342780277-786X
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