Updated on 2022/05/25

写真a

 
NAKAZATO, Hidenori
 
Affiliation
Faculty of Science and Engineering, School of Fundamental Science and Engineering
Job title
Professor

Concurrent Post

  • Faculty of Science and Engineering   Graduate School of Fundamental Science and Engineering

  • Affiliated organization   Global Education Center

Research Institute

  • 2020
    -
    2022

    理工学術院総合研究所   兼任研究員

  • 2020
    -
    2022

    国際情報通信研究センター   兼任研究員

Education

  •  
    -
    1993

    Universit of Illinois   Computer Science  

  •  
    -
    1982

    Waseda University   Faculty of Science and Engineering  

Degree

  • イリノイ大学   学術博士

  • Universit of Illinois   Ph.D. in Computer Science

  • イリノイ大学   科学修士

  • Universit of Illinois   M.S. in Computer Science

  • Ph.D

Research Experience

  • 1997
    -
    2000

    Oki Electric Industry, Co. Ltd, Kansai Laboratories, Research

  • 1997
    -
    2000

    Oki Electric Industry, Co. Ltd, Kansai Laboratories, Research

  • 1993
    -
    1997

    Oki Electric Industry, Co. Ltd, Central Switching System Division, Researcher

  • 1993
    -
    1997

    Oki Electric Industry, Co. Ltd, Central Switching System Division, Researcher

Professional Memberships

  •  
     
     

    IPSJ

  •  
     
     

    IEICE

  •  
     
     

    ACM

  •  
     
     

    IEEE

 

Research Areas

  • Software

  • Communication and network engineering

  • Computer system

Research Interests

  • Information Centric Networking, Distributed Systems, Communication Quality, Performance

Papers

  • IoT-centric service function chainingorchestration and its performance validation

    Hibiki Sekine, Kenji Kanai, Jiro Katto, Hidehiro Kanemitsu, Hidenori Nakazato

    2021 IEEE 18th Annual Consumer Communications and Networking Conference, CCNC 2021    2021.01

     View Summary

    In order to simplify deployment and management of IoT services, Network Function Virtualization (NFV) and Service Function Chaining (SFC) are promising solutions, and much researchers have conducted these topics. To enhance the reliability of former research efforts, in this paper, we propose an orchestration framework for IoT-centric SFC by using Docker and Kubernetes. The framework enables an automatic IoT service deployment by satisfying service requirements and computing and network resource constraints. In such deployment, we apply a Virtual Network Function (VNF)/Service Function (SF) placement problem to achieve efficient utilization of the resources. We set an objective function as minimizing both numbers of SF instances and communications and build a mathematical model based on Integer Linear Programming (ILP). To validate it, we implement a model for the framework and evaluate the performances by carrying out a numerical evaluation and a real experiment. From the evaluation results, we confirm that the proposed approach can reduce the number of SF placements and the number of communications among SF instances.

    DOI

  • Real-World Implementation of Function Chaining in Named Data Networking for IoT Environments

    Yohei Kumamoto, Hiroki Yoshii, Hidenori Nakazato

    2020 IEEE International Workshop Technical Committee on Communications Quality and Reliability (CQR)    2020.05

    DOI

  • A function clustering algorithm for resource utilization in service function chaining

    Hidehiro Kanemitsu, Kenji Kanai, Jiro Katto, Hidenori Nakazato

    IEEE International Conference on Cloud Computing, CLOUD   2019-July   193 - 195  2019.07

     View Summary

    Abstract-Virtualized service and network functions are deployed on virtual machines (VMs) to realize essential processing to realize service function chaining (SFC). Issues on SFC is SF allocation to a VM and to minimize the response time and number of function instances. In this paper, we propose an SF clustering-based scheduling algorithm, called 'SF-clustering for utilizing virtual CPUs' (SFCUV), to solve the SF allocation and SF selection problems simultaneously. Experimental results show that SF-CUV can utilize vCPUs to minimize the response time.

    DOI

  • Performance evaluations of iot device virtualization for efficient resource utilization

    Keigo Ogawa, Hibiki Sekine, Kenji Kanai, Kenichi Nakamura, Hidehiro Kanemitsu, Jiro Katto, Hidenori Nakazato

    Global IoT Summit, GIoTS 2019 - Proceedings    2019.06

     View Summary

    To develop and interoperate smart city applications efficiently, smart city IoT platforms require efficient handling of various types of sensor devices, networking and computing resources, and different domain applications. To address this fact, the authors of this paper proposed a research project named 'Fed4IoT', which is an acronym for federation of IoT and cloud infrastructures, to provide scalable and interoperable smart city applications. The project primarily proposes two key technologies: IoT device virtualization and context-information sharing. In this paper, we introduce the IoT device virtualization (one of key technology in Fed4IoT) that enables efficient utilization of networking and computing resources by applying a micro-service sharing and dynamic resource scaling. In the performance evaluations, we implement three micro services, such as object detection, garbage detection and road damage detection, as smart city applications and dynamically and flexibly allocate computing resources to three micro services by using Docker and Kubernetes. Through the evaluations we validate that the proposed IoT device virtualization achieves the efficient computing resource utilization and reduction of networking resources.

    DOI

  • IoT Device Virtualization for Efficient Resource Utilization in Smart City IoT Platform

    Keigo Ogawa, Kenji Kanai, Kenichi Nakamura, Hidehiro Kanemitsu, Jiro Katto, Hidenori Nakazato

    2019 IEEE International Conference on Pervasive Computing and Communications Workshops, PerCom Workshops 2019     419 - 422  2019.03

     View Summary

    To develop and interoperate smart city applications efficiently, smart city IoT platforms require efficient handling of various types of sensor devices, networking and computing resources, and different domain applications. To address this fact, in this paper, we introduce an IoT device virtualization that enables efficient utilization of computing resources. The proposal applies a micro-service sharing and dynamic resource scaling. In the performance validations, we implement an early prototype using Docker, Kubernetes, and Apache Kafka. Through the preliminary experiment, we confirm that the proposal can improve the application processing time by appropriately sharing and scaling micro services.

    DOI

  • Information-Centric Networking: Research and Standardization Status

    Keping Yu, Suyong Eum, Toshihiko Kurita, Qiaozhi Hua, Takuro Sato, Hidenori Nakazato, Tohru Asami, Ved P. Kafle

    IEEE Access   7   126164 - 126176  2019

     View Summary

    Information-centric networking (ICN) is a new approach to networking contents rather than devices that hold the contents. It has recently attracted much attention of network research and standardization communities. National and multi-national funded research projects have progressed worldwide. International Telecommunication Union-Telecommunication Standardization Sector (ITU-T) started ICN standardization activities in 2012. In parallel, the standards-oriented research cooperation is progressing in the Information-Centric Networking Research Group (ICNRG) of the Internet Research Task Force (IRTF). All these global efforts have been collectively advancing the novel network architecture of ICN. However, there are very few surveys and discussions on the detailed ICN standardization status. To update the reader with information about the ICN research and standardization related activities, this paper starts with the history of global activities on ICN from 2010, giving references to various projects. It then describes the recent progress in the standardization of ICN component technologies in ITU-T and various documents produced by ICNRG. Lastly, it discusses the future directions for progressing ICN.

    DOI

  • Performance evaluations of multimedia service function chaining in edge clouds

    Kentaro Imagane, Kenji Kanai, Jiro Katto, Toshitaka Tsuda, Hidenori Nakazato

    2018 15th IEEE Annual Consumer Communications & Networking Conference (CCNC)   2018-January   1 - 4  2018.01

     View Summary

    As mobile multimedia services have significantly evolved and diversified with the spread of smartphones and Internet of Things (IoT) devices, low-delay multimedia cloud computing is the need of the hour. To address this demand, in this study, we introduce an edge cloud system that equips a multimedia service function chaining capability. A prototype implementation of the proposed edge cloud system has three main features: 1) edge computing deployment by using OpenStack, 2) multimedia service slicing and chaining, and 3) efficient resource management in edge networks. Based on these features, the proposed system achieves lower multimedia processing delay compared to a conventional cloud computing platform. We deploy the proposed system in our laboratory and validate the system performance by using typical multimedia application, such as human detection in video surveillance.

    DOI

  • Request expectation index based cache replacement algorithm for streaming content delivery over ICN

    Haipeng Li, Hidenori Nakazato, Syed Hassan Ahmed

    Future Internet   9 ( 4 )  2017.11

     View Summary

    Since the content delivery unit over Information-Centric Networking (ICN) has shifted from files to the segments of a file named chunks, solely either file-level or chunk-level request probability is insufficient for ICN cache management. In this paper, a Request Expectation Index (RXI) based cache replacement algorithm for streaming content delivery is proposed. In this algorithm, RXI is introduced to serve as a fine-grained and unified estimation criteria of possible future request probability for cached chunks. RXI is customized for streaming content delivery by adopting both file-level and chunk-level request probability and considering the dynamically varied request status at each route as well. Compared to prior work, the proposed algorithm evicts the chunk with the minimum expectation of future request to maintain a high cache utilization. Additionally, simulation results demonstrate that the RXI-based algorithm can remarkably enhance the streaming content delivery performance and can be deployed in complex network scenarios. The proposed results validate that, by taking fine-grained request probability and request status into consideration, the customized in-network caching algorithm can improve the ICN streaming content delivery performance by high cache utilization, fast content delivery, and lower network traffic.

    DOI

  • Prior node selection for scheduling workflows in a heterogeneous system

    Hidehiro Kanemitsu, Masaki Hanada, Hidenori Nakazato

    JOURNAL OF PARALLEL AND DISTRIBUTED COMPUTING   109   155 - 177  2017.11  [Refereed]

     View Summary

    Many workflow scheduling algorithms for heterogeneous systems have been developed to satisfy multiple requirements such as minimizing schedule length while maximizing throughput. In particular, in list-based scheduling approaches, the schedule length depends on the given nodes as well as the task allocation and ordering policies. This is because the scheduling priority is derived by averaging the execution time and communication time of the given nodes. If the set of nodes can be adjusted before the scheduling tasks, a small schedule length can be achieved. In this paper, we propose a prior node selection algorithm, called lower bound based candidate node selection (LBCNS) to select a subset of given nodes to minimize the schedule length while fairly scheduling each job. Our proposal has two approaches: (i) LBCNS_DEFAULT, which considers the job characteristics and each node's performance, and (ii) priority-based LBCNS, which additionally takes each scheduling priority into account for a dedicated task scheduling algorithm.
    The experimental results of extensive simulations show that LBCNS_DEFAULT has the best fairness for scheduling multiple workflow jobs, while priority-based LBCNS achieves the minimum schedule length with the highest efficiency for a single workflow job and multiple workflow jobs. (C) 2017 Elsevier Inc. All rights reserved.

    DOI

  • Efficient producer mobility support in named data networking

    Siran Zhang, Zhiwei Yan, Yong-Jin Park, Hidenori Nakazato, Wataru Kameyama, Kashif Nisar, Ag Asri Ag Ibrahim

    IEICE Transactions on Communications   E100B ( 10 ) 1856 - 1864  2017.10

     View Summary

    Named Data Networking (NDN) is a promising architecture for the future Internet and it is mainly designed for efficient content delivery and retrieval. However, producer mobility support is one of the challenging problems of NDN. This paper proposes a scheme which aims to optimize the tunneling-based producer mobility solution inNDN. It does not require NDN routers to change their routing tables (Forwarding Information Base) after a producer moves. Instead, the Interest packet can be sent from a consumer to the moved producer using the tunnel. The piggybacked Data packet which is sent back to the consumer will trigger the consumer to send the following Interest packets through the optimized path to the producer. Moreover, a naming scheme is proposed so that the NDN caching function can be fully utilized. An analysis is carried out to evaluate the performance of the proposal. The results indicate that the proposed scheme reduces the network cost compared to related works and supports route optimization for enhanced producer mobility support in NDN.

    DOI

  • Network Mobility in a Locator/ID Separation Context

    Zhiwei Yan, Syed Hassan Ahmed, Guanggang Geng, Hidenori Nakazato, Yong-Jin Park

    IEEE Access   5   27897 - 27904  2017

     View Summary

    Internet Engineering Task Force (IETF) has proposed an extension based on Mobile IPv6 (MIPv6), named as network mobility basic support protocol (NEMO-BSP), to support NEMO in IPv6 networks. However, NEMO-BSP inherits all the drawbacks of MIPv6, such as inefficient routing path, high handover latency, and packet encapsulation overhead. To address these drawbacks of NEMO-BSP, this paper proposes an NEMO supporting scheme based on a novel Locator/ID Separation (LIDS) architecture, namely LIDS-NEMO. In LIDS-NEMO, Multiple Virtual Mapping (MVM) scheme is proposed to differentiate the intra-NEMO and inter-NEMO mobility. Besides, packets are transmitted through the most optimized route in LIDS-NEMO. The simulation results show that LIDS-NEMO reduces the signaling cost significantly when compared with NEMO-BSP and it will be a promising scheme to provide NEMO support in the LIDS context.

    DOI

  • Two-Level Popularity-Oriented Cache Replacement Policy for Video Delivery over CCN

    Haipeng Li, Hidenori Nakazato

    IEICE TRANSACTIONS ON COMMUNICATIONS   E99B ( 12 ) 2532 - 2540  2016.12  [Refereed]

     View Summary

    We introduce a novel cache replacement policy to improve the entire network performance of video delivery over content-centric networking (CCN). In the case of the CCN structure, we argue that: 1) for video multiplexing scenario, general cache strategies that ignore the intrinsic linear time characteristic of video requests are unable to make better use of the cache resources, and 2) it is inadequate to simply extend the existing research conclusions of file-oriented popularity to chunk-by-chunk popularity, which are widely used in CCN. Unlike previous works in this field, the proposed policy in this study, named two-level popularity-oriented time-to-hold cache replacement policy (TLP-TTH), is designed on the basis of the following principles. Firstly, the proposed cache replacement strategy is customized for video delivery by carefully considering the essential auto-correlated request feature of video chunks within a video file. Furthermore, the popularity in video delivery is subdivided into two levels, namely chunk-level access probability and file-level popularity, in order to efficiently utilize cache resources. We evaluated the proposed policy in both a hierarchical topology and a real network based hybrid topology, and took viewers departure into consideration as well. The results validate that for video delivery over CCN, TLP-TTH policy improves the network performance from several aspects. In particular, we observed that the proposed policy not only increases the cache hit ratio at the edge of the network but the cache utilization at the intermediate routers is also improved markedly. Further, with respect to the video popularity variation scenario, the cache hit ratio of TLP-TTH policy responds sensitively to maintain efficient cache utilization.

    DOI

  • Clustering-Based Task Scheduling in a Large Number of Heterogeneous Processors

    Hidehiro Kanemitsu, Masaki Hanada, Hidenori Nakazato

    IEEE TRANSACTIONS ON PARALLEL AND DISTRIBUTED SYSTEMS   27 ( 11 ) 3144 - 3157  2016.11  [Refereed]

     View Summary

    Parallelization paradigms for effective execution in a Directed Acyclic Graph (DAG) application have been widely studied in the area of task scheduling. Schedule length can be varied depending on task assignment policies, scheduling policies, and heterogeneity in terms of each processor and each communication bandwidth in a heterogeneous system. One disadvantage of existing task scheduling algorithms is that the schedule length cannot be reduced for a data intensive application. In this paper, we propose a clustering-based task scheduling algorithm called Clustering for Minimizing the Worst Schedule Length (CMWSL) to minimize the schedule length in a large number of heterogeneous processors. First, the proposed method derives the lower bound of the total execution time for each processor by taking both the system and application characteristics into account. As a result, the number of processors used for actual execution is regulated to minimize the Worst Schedule Length (WSL). Then, the actual task assignment and task clustering are performed to minimize the schedule length until the total execution time in a task cluster exceeds the lower bound. Experimental results indicate that CMWSL outperforms both existing list-based and clustering-based task scheduling algorithms in terms of the schedule length and efficiency, especially in data-intensive applications.

    DOI

  • [Invited Talk] GreenICN: Research Project on Energy-Saving Information Centric Network

    Hidenori Nakazato

    IEICE Technical Repot   IN2015-45  2015.09

  • Energy Consumption Evaluation of ICN Toward Power-Saving Video Delivery

    Daiki Aoki, Sakiko Takenaka, Kenji Kanai, Jiro Katto, Hidenori Nakazato, Marie Hirose

    2015 IEEE INTERNATIONAL CONFERENCE ON DATA SCIENCE AND DATA INTENSIVE SYSTEMS     390 - 395  2015  [Refereed]

     View Summary

    Information Centric Networking (ICN) is a new networking paradigm in which the network provides users with named content, instead of communication channels between hosts. However, many issues, such as naming, routing, resource control, and security, still need to be resolved before it can be realized practically. Further, the energy efficiency of ICNs has not been sufficiently considered. In this study, we evaluate the energy consumption of an ICN network by first measuring the power consumption of actual PCs/smartphones and constructing an energy consumption model. Then, by using the model and the simulator ndnSIM, we calculate the energy consumed by the network. We also evaluate the energy consumed for video delivery, with a view toward power-saving video delivery.

    DOI

  • Effective Parallel Algorithm for GPGPU-Accelerated Explicit Routing Optimization

    Ko Kikuta, Eiji Oki, Naoaki Yamanaka, Nozomu Togawa, Hidenori Nakazato

    2015 IEEE GLOBAL COMMUNICATIONS CONFERENCE (GLOBECOM)    2015  [Refereed]

     View Summary

    The recent development of network technologies that offer centralized control of explicit routes opens the door to the online optimization of explicit routing. For this kind of Traffic Engineering optimization, raising the calculation speeds by using multi-core processors with effective parallel algorithms is a key goal. This paper proposes an effective parallel algorithm for General purpose Programming on Graphic Processing Unit (GPGPU); its massively parallel style promises strong acceleration of calculation speed. The proposed algorithm parallelizes not only the search method of the Genetic Algorithm, but also its fitness functions, which calculate the network congestion ratio, so as to fully utilize the power of modern GPGPUs. Concurrently, each execution is designed for thread-block execution on the GPU with consideration of thread occupancy, local resources, and SIMT execution to maximize GPU performance. Evaluations show that the proposed algorithm offers, on average, a nine fold speedup compared to the conventional CPU approach.

  • QoS Implementation in System Wide Information Management (SWIM) Network Model

    Kiratipong Ongkasae, Hideori Nakazato, Tadashi Koga, Xiaodong Lu

    2015 IEEE 12TH INTERNATIONAL SYMPOSIUM ON AUTONOMOUS DECENTRALIZED SYSTEMS ISADS 2015     181 - 184  2015  [Refereed]

     View Summary

    A Traditional Air Traffic Management (ATM) system comprises of a wide variety of information services that characterized by many custom communication protocols. Each service is a self-contained information system by itself. Each of these services is custom designed, developed, managed, and maintained individually and locally at a significant cost [1]. System-Wide Information Management (SWIM) is a concept for modern ATM systems that present a complete change in paradigm of how ATM related information is handled and shared while services interoperate. The aim of SWIM is to provide information to users with understandable information. However, such a large amount of information that flow through a network may affect overall system performance. Quality of Service (QoS) describes network performance parameters reflect the quality of the connection and is experienced on end-to-end traffic flow.
    In this paper, we propose a model base on SWIM with implementation of Quality of Service configuration and application of network virtualization technique to separate network traffic into individual services, which intent to improve the quality of end-to-end network traffic. This network model is developed and deployed using Juniper MX series router.

    DOI

  • Popularity Proportional Cache Size Allocation Policy for Video Delivery on CCN

    Haipeng Li, Hidenori Nakazato, Andrea Detti, Nicola Blefari Melazzi

    2015 EUROPEAN CONFERENCE ON NETWORKS AND COMMUNICATIONS (EUCNC)     434 - 438  2015  [Refereed]

     View Summary

    Content Centric Networking (CCN), which is regarded as an innovational architecture of future network, is increasingly gaining attention in recent years. Based on the observation of current Internet usage, CCN presents a content-centric model which focuses on data distribution and retrieval. To enhance the efficiency of content distribution, In-network caching is adopted, which enables routers to temporarily store the passing by data. Thus the scheme of cache management will affect the network performance significantly. In this paper, a cache replacement policy named Popularity Proportional Cache Size Allocation (PPCSA) policy has been proposed, which designed for video content delivery on CCN. Unlike other previous works in this area, which have focused on the popularity of individual content chunks, in this study, we not only consider the title-level popularity of a video which is composed of a set of video segments, but also take the chunk-level probability of video segments within a video title into consideration. We evaluated our policy through simulations, by using a simple 4-level tree topology and a real network based hybrid topology. The results validate that on both scenarios, the proposed approach can increase the average cache hit ratio and shorten the average content delivery distance between requesters and object contents. In addition, we analyzed the energy efficiency of PPCSA policy, and we found that compared to other three cache replacement policies, Least Recently Used (LRU), Least Frequently Used (LFU) and First in First out (FIFO), PPCSA reduced the transmission energy consumption, and improved the energy efficiency in idle time.

  • On-Path Resolver Architecture for Mobility Support in Information Centric Networking

    Hidenori Nakazato, Siran Zhang, Yong Jin Park, Andrea Detti, Dariusz Bursztynowski, Zbigniew Kopertowski, Ioannis Psaras

    2015 IEEE GLOBECOM WORKSHOPS (GC WKSHPS)    2015  [Refereed]

     View Summary

    Video traffic shares a large portion of the current Internet bandwidth. One of the objectives of designing Named Data Networking (NDN) is to reduce the burden of the large content delivery. Since mobile devices are the prime means of content access for many users, NDN is also required to support mobility. In this paper, we propose an architecture and mechanism called On-Path Resolver Architecture (OPRA) for NDN to support both consumer and producer mobility while maintaining scalability. OPRA exploits the semantics of hierarchical-name-based routing and places route resolvers on multiple points on a path to a content. The series of resolvers on a path provides means to contain naming scope and makes the system scalable while supporting mobility.

  • [Special Invited Talk] Network Coding and Speedup of Data Transfer

    Hidenori Nakazato

    IEICE Technical Repot   CS2014-7  2014.05

  • Effective Use of Computational Resources in Multicore Distributed Systems

    Hidehiro Kanemitsu, Masaki Hanada, Takashige Hoshiai, Hidenori Nakazato

    2014 16TH INTERNATIONAL CONFERENCE ON ADVANCED COMMUNICATION TECHNOLOGY (ICACT)     305 - +  2014  [Refereed]

     View Summary

    In the last decades, many kinds of task models such as grid and cloud computing have been developed. In such distributed systems, each task is processed by respective processor in multicored computers e.g., household PCs which we can easily harness in recent years. If there is one policy to automatically decide the "best" combination and the number of processors (and computers), we effectively utilize those computational resources, thereby large number of jobs can be executed in parallel. In this paper, we propose a method for mapping of execution units for such environments. The method adopts a remapping technology after processor-execution unit mapping[11] is finished. Experimental comparisons by a simulation show the advantages of the proposed method.

  • Message routing with counting bloom filter for name-based home ad hoc networks

    Vidanagama, T.N, Nakazato, H

    International Journal of Computer Science and Network   3 ( 1 ) 15 - 23  2014.01

  • Minimal Network Coding Redundancy for Peer-to-Peer Content Distribution

    Dinh Nguyen, Hidenori Nakazato

    2014 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS (ICC)     3112 - 3117  2014  [Refereed]

     View Summary

    Network coding, with the redundant information it generates, has been shown to achieve optimal multicast throughput. Such redundancy plays a key role in maximizing throughput over multiple content delivery paths between network nodes. In this paper, we study the use of network coding to speed up content distribution in peer-to-peer networks where only a constraint number of selected peers can encode, i.e. become network coders. Our goal is to optimize the redundancy network coding generates, i.e. we want to answer the question how much a given network coder should encode. This serves as a step towards understanding how network coding improves content distribution in order to optimize its deployment. Given the network topology, we analytically figure the optimal redundancy ratio at each network coder to achieve shortest distribution time. Simulation results confirm the effectiveness of the proposed coding redundancy in shortening content distribution time while noticeably reducing the amount of encoding.

  • Dynamic Scheduling for Speculative Execution to Improve MapReduce Performance in Heterogeneous Environment

    Hyungjae Jung, Hidenori Nakazato

    2014 IEEE 34TH INTERNATIONAL CONFERENCE ON DISTRIBUTED COMPUTING SYSTEMS WORKSHOPS (ICDCSW)     119 - 124  2014  [Refereed]

     View Summary

    MapReduce framework allows users to quickly develop big-data applications and process big-data effectively. However, unexpected malfunction may be found in cloud environment because a distributed system consists of several hardware, and this malfunction often causes delay of overall processing. MapReduce framework provides Speculative Execution (SE). SE reduces delay in a homogeneous environment by assigning delayed tasks to additional nodes. As cloud computing prevails, cloud computing environment is moving from homogeneous to heterogeneous. Original SE is not perfect and sometimes produces inefficient result in a heterogeneous environment. This paper proposes Dynamic Scheduling for Speculative Execution (DSSE) which enhances performance in a heterogeneous environment by improving existing SE. DSSE prevents wasted SE since it calculates processing capability of each node more objectively and precisely. DSSE has reduced entire processing time approximately 10% compared to original SE. Success rate of SE was 100%.

    DOI

  • Name-Based Message Forwarding for Home Ad hoc Networks

    Vidanagama, T.N, Nakazato, H

    Journal of Wireless Networking and Communications   3 ( 4 ) 51 - 62  2013.10

  • Mobility in Name-Based Home Ad Hoc Networks

    Vidanagama, T.N, Nakazato, H

    International Journal of Engineering and Advanced Technology   2 ( 6 ) 87 - 95  2013.08

  • Network Coder Placement for Peer-to-Peer Content Distribution

    Dinh Nguyen, Hidenori Nakazato

    IEICE TRANSACTIONS ON COMMUNICATIONS   E96B ( 7 ) 1661 - 1669  2013.07  [Refereed]

     View Summary

    We study the use of network coding to speed up content distribution in peer-to-peer (P2P) networks. Our goal is to get the underlying reason for network coding's improved performance in P2P content distribution and to optimize resource consumption of network coding. We observe analytically and experimentally that in pure P2P networks, a considerable amount of data is sent multiple times from one peer to another when there are multiple paths connecting those two particular peers. Network coding, on the other hand, when applied at upstream peers, eliminates information duplication on paths to downstream peers, which results in more efficient content distribution. Based on that insight, we propose a network coder placement algorithm which achieves comparable distribution time as network coding, yet substantially reduces the number of encoders compared to a pure network coding solution in which all peers have to encode. Our placement method puts encoders at critical network positions to eliminate information duplication the most, thus, effectively shortens distribution time with just a portion of encoders.

    DOI

  • 動的なパス設定制御に基づく1+1パスプロテクション維持方式の提案

    鎌村 星平, 島崎 大作, 平松 淳, 中里 秀則

    電子情報通信学会論文誌(B)   Vol.J96-B ( No.2 ) 48 - 58  2013.02

  • Autonomous IP Fast Rerouting with Compressed Backup Flow Entries Using OpenFlow

    Shohei Kamamura, Daisaku Shimazaki, Atsushi Hiramatsu, Hidenori Nakazato

    IEICE TRANSACTIONS ON INFORMATION AND SYSTEMS   E96D ( 2 ) 184 - 192  2013.02  [Refereed]

     View Summary

    This paper proposes an IP fast rerouting method which can be implemented in OpenFlow framework. While the current IP is robust, its reactive and global rerouting processes require the long recovery time against failure. On the other hand, IP fast rerouting provides a milliseconds-order recovery time by proactive and local restoration mechanism. Implementation of IP fast rerouting is not common in real systems, however; it requires the coordination of additional forwarding functions to a commercial hardware. We propose an IP fast rerouting mechanism using OpenFlow that separates control function from hardware implementation. Our mechanism does not require any extension of current forwarding hardware. On the contrary, increase of backup routes becomes main overhead of our proposal. We also embed the compression mechanism to our IP fast rerouting mechanism. We show the effectiveness of our IP fast rerouting in terms of the fast restoration and the backup routes compression effect through computer simulations.

    DOI

  • Effective Use of Computational Resources In Multicore Distributed Systems

    Hidehiro Kanemitsu, Masaki Hanada, Takashige Hoshiai, Hidenori Nakazato

    2013 15TH INTERNATIONAL CONFERENCE ON ADVANCED COMMUNICATION TECHNOLOGY (ICACT)     325 - 330  2013  [Refereed]

     View Summary

    In the last decades, many kinds of task execution models such as grid and cloud computing have been developed. In such distributed systems, each task is processed by respective processor in multi cored computers e. g., household PCs which we can easily harness in recent years. If there is one policy to automatically decide the "best" combination and the number of processors (and computers), we effectively utilize those computational resources, thereby large number of jobs can be executed in parallel. In this paper, we propose a method for mapping of execution units for such environments. T he method adopts a re-mapping technology after processor-execution unit mapping[6] is finished. Experimental comparisons by a simulation show the advantages of the proposed method.

  • Loop-Free IP Fast Rerouting Considering Double-Link Failures

    Shohei Kamamura, Daisaku Shimazaki, Atsushi Hiramatsu, Hidenori Nakazato

    IEICE TRANSACTIONS ON COMMUNICATIONS   E95B ( 12 ) 3811 - 3821  2012.12  [Refereed]

     View Summary

    IP fast rerouting has widely been studied for realizing millisecond-order recovery on pure IP networks. This paper proposes IP fast rerouting using backup topologies against concurrent double failures. The main issue in recovering from multiple failures is avoiding forwarding loops. To avoid forwarding loops, we propose a deterministic forwarding algorithm, which estimates the concurrently occurring failures from the packet header information. We also propose an efficient backup topology design algorithm which is both loop-free and which reduces the number of backup topologies. Our key idea is preparing the adequate diversity of backup routes for arbitrary source and destination pairs by combination of backup topologies. For efficient computation of diverse routes, we propose a similarity comparison-based algorithm between the original topology and the backup topologies. Our algorithm can achieve nearly optimal loop-free restoration from double failures on realistic topologies without explicit failure notification.

    DOI

  • Call Admission Control on Single Node Networks under Output Rate-Controlled Generalized Processor Sharing (ORC-GPS) Scheduler

    Masaki Hanada, Hidenori Nakazato, Hitoshi Watanabe

    IEICE TRANSACTIONS ON COMMUNICATIONS   E95B ( 2 ) 401 - 414  2012.02  [Refereed]

     View Summary

    Multimedia applications such as music or video streaming, video teleconferencing and IP telephony are flourishing in packet-switched networks. Applications that generate such real-time data can have very diverse quality-of-service (QoS) requirements. In order to guarantee diverse QoS requirements, the combined use of a packet scheduling algorithm based on Generalized Processor Sharing (GPS) and leaky bucket traffic regulator is the most successful QoS mechanism. GPS can provide a minimum guaranteed service rate for each session and tight delay bounds for leaky bucket constrained sessions. However, the delay bounds for leaky bucket constrained sessions under GPS are unnecessarily large because each session is served according to its associated constant weight until the session buffer is empty. In order to solve this problem, a scheduling policy called Output Rate-Controlled Generalized Processor Sharing (ORC-GPS) was proposed in [17]. ORC-GPS is a rate-based scheduling like GPS, and controls the service rate in order to lower the delay bounds for leaky bucket constrained sessions. In this paper, we propose a call admission control (CAC) algorithm for ORC-GPS, for leaky-bucket constrained sessions with deterministic delay requirements. This CAC algorithm for ORC-GPS determines the optimal values of parameters of ORC-GPS from the deterministic delay requirements of the sessions. In numerical experiments, we compare the CAC algorithm for ORC-GPS with one for GPS in terms of schedulable region and computational complexity.

    DOI

  • 計算資源の有効利用を目的としたタスククラスタリング

    金光 永煥, 李 吉憲, 中里 秀則, 星合 隆成, 浦野 義頼

    情報処理学会論文誌(ACS:コンピューティングシステム)   4 ( 1 ) 111 - 146  2011.02

  • Peer-to-Peer Content Distribution in Clustered Topologies with Source Coding

    Dinh Nguyen, Hidenori Nakazato

    2011 IEEE GLOBAL TELECOMMUNICATIONS CONFERENCE (GLOBECOM 2011)    2011  [Refereed]

     View Summary

    Network coding has been applied successfully in peer-to-peer systems to shorten the distribution time, particularly in extreme conditions where peers in the network are clustered and separated by physical links with limited bandwidth. In this paper, we focus more closely on the use of source coding, i.e. encoding is done only at the source, as an alternative to network coding to facilitate content distribution under such limited bandwidth configuration. We observe analytically and experimentally that, in this specific case, with appropriately chosen expansion factors, source coding can have comparable performance to network coding in terms of distribution time, yet consuming much less computational resources than the latter approach does.

  • Reduction of Message Misdirection in Description Based Clustered Ad Hoc Networks

    Tharinda Nishantha Vidanagama, Hidenori Nakazato

    2010 7TH IEEE CONSUMER COMMUNICATIONS AND NETWORKING CONFERENCE-CCNC 2010     639 - 643  2010  [Refereed]

     View Summary

    Future home appliances will have many useful built-in functions. A communication network that allows a user to access these built-in functions and to control the appliances is highly desirable. An ad hoc network can be easily deployed to connect these home appliances. For such a home network, ease of use must be given higher consideration. This paper discusses description based ad-hoc network routing where the nodes are given descriptions or keywords such as living room TV, kitchen oven etc. as identifiers. We propose three description based routing mechanisms: Single Routing Cache, Directional Routing Cache, and Proportional-Directional Routing Cache. Through simulation, we show that in all three methods the message delivery is 100% success in our configuration, but the amount of misdirected messages experienced by each method is different. The Proportional-Directional Routing Cache shows the least message misdirection with most preferable resource usage.

  • Output Rate-Controlled Generalized Processor Sharing: End-to-End Delay Bounds Calculation

    Masaki Hanada, Hidenori Nakazato, Hitoshi Watanabe

    TENCON 2010: 2010 IEEE REGION 10 CONFERENCE     779 - 784  2010  [Refereed]

     View Summary

    Recently multimedia applications such as music or video streaming, video teleconferencing and IP telephony have been flourishing in packet-switched networks. Applications that generate such real-time data can have very diverse quality-of-service (QoS) requirements.
    In order to guarantee diverse QoS requirements, the combined use of a packet scheduling algorithm based on Generalized Processor Sharing (GPS) and leaky bucket traffic regulator is the most successful QoS mechanism. GPS can provide a minimum guaranteed service rate for each session and tight delay bounds for leaky bucket constrained sessions. However, the delay bounds for leaky bucket constrained sessions under GPS are unnecessarily large constant weight until the session buffer is empty. In order to solve the problem, a scheduling policy called Output Rate-Controlled Generalized Processor Sharing (ORC-GPS) has been proposed in [10]. ORC-GPS is a rate-based scheduling like GPS, and controls the service rate in order to lower the delay bounds for leaky bucket constrained sessions.
    In this paper, we extend the delay bounds calculation for single-node networks introduced in [10] to multi-node networks and compare ORC-GPS with GPS in terms of end-to-end delay bounds through numerical experiments.

  • Mobility in a Description based Clustered Ad Hoc Network

    Tharinda Nishantha Vidanagama, Hidenori Nakazato

    2010 IEEE GLOBECOM WORKSHOPS     148 - 152  2010  [Refereed]

     View Summary

    Wireless mobile ad hoc networks can be used as a means to ease and support life in an ordinary house. As future home appliances will have many useful built-in functions, a communication network that allows a user to access these built-in functions and to control the appliances is highly desirable. This paper proposes a routing algorithm for mobility in a description-based clustered ad-hoc network where the nodes are given descriptions or keywords such as "living room TV", "kitchen oven", etc. as identifiers. In this paper, we discuss and compare the routing and the number of control messages required to achieve a higher message delivery success rate for frequent and infrequent communication of nodes with mobility. When communication is infrequent a search is performed for the destination regardless of mobility. The proposed algorithm handles mobility efficiently while ensuring a high accuracy on message delivery with the least amount of control messages.

  • Analysis of Divisible Load Scheduling with result collection on heterogeneous systems

    Abhay Ghatpande, Hidenori Nakazato, Olivier Beaumont, Hiroshi Watanabe

    IEICE TRANSACTIONS ON COMMUNICATIONS   E91B ( 7 ) 2234 - 2243  2008.07  [Refereed]

     View Summary

    Divisible Load Theory (DLT) is an established framework to study Divisible Load Scheduling (DLS). Traditional DLT ignores the result collection phase, and specifies no solution to the general case where both the network speed and computing capacity of the nodes are heterogeneous. In this paper, the DLS with Result Collection on HETerogeneous Systems (DLSRCHETS) problem is formulated as a linear program and analyzed. The papers to date that have dealt with result collection, proposed Simplistic LIFO (Last In, First Out) and FIFO (First In, First Out) type of schedules as solutions. The main contributions of this paper are: (a) A proof of the Allocation Precedence Condition, which is inconsequential in LIFO or FIFO, but is important in a general schedule. (b) A proof of the Idle Time Theorem, which states that irrespective of whether load is allocated to all available processors, in the optimal solution to the DLSRCHETS problem, at the most one processor that is allocated load has idle time, and that the idle time exists only when the result collection begins immediately after the completion of load distribution.

    DOI

  • Divisible Load Scheduling with result collection on heterogeneous systems

    Abhay Ghatpande, Hidenori Nakazato, Hiroshi Watanabe, Olivier Beaumont

    2008 IEEE INTERNATIONAL SYMPOSIUM ON PARALLEL & DISTRIBUTED PROCESSING, VOLS 1-8     372 - +  2008  [Refereed]

     View Summary

    Divisible Load Theory (DLT) is an established mathematical framework to study Divisible Load Scheduling (DLS). However traditional DLT does not comprehensively deal with the scheduling of results back to source (i.e., result collection) on heterogeneous systems. In this paper, the DLSRCHETS (DLS with Result Collection on HETerogeneous Systems) problem is addressed. The few papers to date that have dealt with DLSRCHETS, proposed simplistic LIFO (Last In, First Out) and FIFO (First In, First Out) type of schedules as solutions to DLSRCHETS. In this paper, a new heuristic algorithm, ITERLP, is proposed as a solution to the DLSRCHETS problem. With the help of simulations, it is proved that the performance of ITERLP is significantly better than existing algorithms.

  • Divisible load scheduling with result collection on heterogeneous systems

    Abhay Ghatpande, Hidenori Nakazato, Hiroshi Watanabe, Olivier Beaumont

    IPDPS Miami 2008 - Proceedings of the 22nd IEEE International Parallel and Distributed Processing Symposium, Program and CD-ROM   E91-B ( 8 ) 2571 - 2588  2008

     View Summary

    Divisible Load Theory (DLT) is an established mathematical framework to study Divisible Load Scheduling (DLS). However, traditional DLT does not comprehensively deal with the scheduling of results back to source (i.e., result collection) on heterogeneous systems. In this paper, the DLSRCHETS (DLS with Result Collection on HETerogeneous Systems) problem is addressed. The few papers to date that have dealt with DLSRCHETS, proposed simplistic LIFO (Last In, First Out) and FIFO (First In, First Out) type of schedules as solutions to DLSRCHETS. In this paper, a new heuristic algorithm, ITERLP, is proposed as a solution to the DLSRCHETS problem. With the help of simulations, it is proved that the performance of ITERLP is significantly better than existing algorithms. ©2008 IEEE.

    DOI

  • Intrusion detection by monitoring system calls with POSIX capabilities

    Takahiro Haruyama, Hidenori Nakazato, Hideyoshi Tominaga

    IEICE TRANSACTIONS ON COMMUNICATIONS   E90B ( 10 ) 2646 - 2654  2007.10  [Refereed]

     View Summary

    Existing anomaly intrusion detection that monitors system calls has two problems: vast false positives and lack of risk information on detection. In order to solve the two problems, we propose an intrusion detection method called "Callchains." Callchains reduces the false positives of existing anomaly intrusion detection by restricting monitoring to the activities with process capabilities prescribed by POSIX 1003. le. Additionally, Callchains provides an administrator information of used POSIX capabilities in sytem call execution as an indicator of risk. This paper shows Callchains' design, its implementation, and experimental results comparing Callchains with existing approaches.

    DOI

  • 遅延保証を目的とした出力レート制御方式ORC-GPS

    花田真樹, 中里秀則

    電子情報通信学会論文誌 B   J90-B ( 2 ) 113 - 126  2007.02

  • ORC-GPS: Output Rate-Controlled Scheduling Policy for Delay Guarantees

    Masaki HANADA, Hidenori NAKAZATO

    IEICE Transactions on Communications   J90-B ( 2 ) 113 - 126  2007.02

  • ORC-GPS: Output rate-controlled scheduling policy for delay guarantees

    Masaki Hanada, Hidenori Nakazato

    2007 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS, VOLS 1-14   J90-B ( 2 ) 530 - 535  2007  [Refereed]

     View Summary

    Recently packet scheduling algorithms such as Packetized GPS (PGPS), Worst-case Fair Weighted Fair Queueing (WF(2)Q) and Self-Clocked Fair Queueing (SCFQ) have been proposed in order to guarantee deterministic or statistical delay bounds. These algorithms are based on Generalized Processor Sharing (GPS) which is an ideal scheduling algorithm based on fluid flow model in which the traffic is infinitely divisible. GPS provides a minimum guaranteed service rate for each session and tight delay bounds for leaky bucket constrained sessions. However, the delay bounds are unnecessarily large because each session is served according to its associated constant weight until the session buffer is empty. In this paper, we present a scheduling policy called Output Rate-Controlled Generalized Processor Sharing (ORC-GPS). ORC-GPS is a rate-based scheduling like GPS and controls the service rate to lower the delay bounds for leaky bucket constrained sessions. In numerical experiments, we compare ORC-GPS with GPS in terms of delay bounds.

  • Output rate-controlled scheduling policy: End-to-end delay bounds calculation

    Masaki Hanada, Hidenori Nakazato

    9TH INTERNATIONAL CONFERENCE ON ADVANCED COMMUNICATION TECHNOLOGY: TOWARD NETWORK INNOVATION BEYOND EVOLUTION, VOLS 1-3     1370 - +  2007  [Refereed]

     View Summary

    Recently many packet scheduling algorithms based on Generalized Processor Sharing (GPS) and Earliest Deadline First (EDF) have been proposed in order to guarantee deterministiic or statistical delay bounds. GPS provides a minimum guaranteed service rate for each session and tight end-to-end delay bounds for leaky bucket constrained sessions. However, the delay bounds are unnecessarily large because each session is served according to its associated constant weight until the session buffer is empty. EDF is the optimal scheduling algorithm in terms of schedulable region in a single-node network. However, using EDF to provide end-to-end delay bounds is problematic because the traffic will be distorted after traffic aggregation in a multi-node network.
    In this paper, we present a scheduling policy called Output Rate-Controlled Generalized Processor Sharing (ORC-GPS) in order to guarantee deterministic delay bounds. ORC-GPS is a rate-based scheduling like GPS and controls the service rate to lower the delay bounds for leaky bucket constrained sessions. We compare ORC-GPS with GPS and EDF in terms of delay bounds.

  • Output rate-controlled scheduling policy: End-to-end delay bounds calculation

    Masaki Hanada, Hidenori Nakazato

    International Conference on Advanced Communication Technology, ICACT   2   1370 - 1375  2007

     View Summary

    Recently many packet scheduling algorithms based on Generalized Processor Sharing (GPS) and Earliest Deadline First (EDF) have been proposed in order to guarantee deterministic or statistical delay bounds. GPS provides a minimum guaranteed service rate for each session and tight end-to-end delay bounds for leaky bucket constrained sessions. However, the delay bounds are unnecessarily large because each session is served according to its associated constant weight until the session buffer is empty. EDF is the optimal scheduling algorithm in terms of schedulable region in a single-node network. However, using EDF to provide end-to-end delay bounds is problematic because the traffic will be distorted after traffic aggregation in a multi-node network. In this paper, we present a scheduling policy called Output Rate-Controlled Generalized Processor Sharing (ORC-GPS) in order to guarantee deterministic delay bounds. ORC-GPS is a rate-based scheduling like GPS and controls the service rate to lower the delay bounds for leaky bucket constrained sessions. We compare ORC-GPS with GPS and EDF in terms of delay bounds.

    DOI

  • 映像配信用マルチキャストトラヒック制御方式Deracs

    西岡淳, 三宅洋一郎, 中里秀則, 富永英義

    電子情報通信学会論文誌 B   J89-B ( 8 ) 1453 - 1463  2006.08

  • Delay-Correlation Driven Rate Control for Streaming Data

    Daisuke Ikegami, Hidenori NAKAZATO, Hideyoshi TOMINAGA

    IEICE Transactions on Communications   J89-B ( 7 ) 1265 - 1274  2006.07

  • ネットワーク遅延時間の相関を用いたストリーミングデータのレート制御方式

    池上大介, 中里秀則, 富永英義

    電子情報通信学会論文誌 B   J89-B ( 7 ) 1265 - 1274  2006.07

  • An approximation analysis of nonpreemptive EDF scheduling

    Masaki Hanada, Hidenori Nakazato

    Electronics and Communications in Japan, Part III: Fundamental Electronic Science (English translation of Denshi Tsushin Gakkai Ronbunshi)   89 ( 2 ) 13 - 23  2006.02  [Refereed]

     View Summary

    Due to recent advances in multimedia technology, a real-time capability is needed to a certain extent even in information systems, in addition to control systems. In general, information systems are classified as soft real-time systems, which keep operating even if a deadline is missed. In soft real-time systems, it is more important to provide statistical guarantees (probabilistic analysis) than absolute guarantees (deadline guarantees). In current real-time systems, real-time scheduling such as EDF (Earliest Deadline First) is used to meet timing constraints. EDF scheduling simply assigns higher priorities in the order of earlier deadlines. It can be applied to aperiodic tasks without prior knowledge of their starting times. In this paper, it is assumed that each attribute of the task follows a probabilistic distribution. The system performance when a nonpreemptive EDF scheduling is applied is then mathematically analyzed. © 2005 Wiley Periodicals, Inc.

    DOI

  • Performance Study on DERACS: A Traffic Control Scheme for Video Multicast

    Jun Nishioka, Yoichiro Miyake, Hidenori Nakazato, Hideyoshi Tominaga

    GLOBECOM 2006 - 2006 IEEE GLOBAL TELECOMMUNICATIONS CONFERENCE    2006

     View Summary

    QoS control for multicast over the Internet is necessary to provide high quality multicast video streaming. With existing DiffServ multicast schemes, multicast traffic in a DiffServ domain increases as the multicast-group membership grows, and consequently packets guaranteed for delivery may be discarded. Since it is hard to guarantee QoS for all flows over the entire network, we propose DERACS a delivery range control scheme which guarantees QoS in a limited delivery range formed by actively discarding packets. In this paper, we show the delivery range of DERACS through simulation and analysis.

  • Performance Study on DERACS: A Traffic Control Scheme for Video Multicast

    Jun Nishioka, Yoichiro Miyake, Hidenori Nakazato, Hideyoshi Tominaga

    GLOBECOM 2006 - 2006 IEEE GLOBAL TELECOMMUNICATIONS CONFERENCE    2006

     View Summary

    QoS control for multicast over the Internet is necessary to provide high quality multicast video streaming. With existing DiffServ multicast schemes, multicast traffic in a DiffServ domain increases as the multicast-group membership grows, and consequently packets guaranteed for delivery may be discarded. Since it is hard to guarantee QoS for all flows over the entire network, we propose DERACS a delivery range control scheme which guarantees QoS in a limited delivery range formed by actively discarding packets. In this paper, we show the delivery range of DERACS through simulation and analysis.

  • Timestamp based optimistic concurrency control

    Quazi Ehsanul Kabir Mamun, Hidenori Nakazato

    TENCON 2005 - 2005 IEEE REGION 10 CONFERENCE, VOLS 1-5   D3-04.1   2551 - +  2006  [Refereed]

     View Summary

    Optimistic Concurrency control demonstrates a few improvements over pessimistic concurrency controls like two-phase locking protocol or time-stamp based protocol. But the price of coarse detection of conflicts may sometimes be high and consequently discounts the advantage of optimistic concurrency control protocol. In this paper we have reduced the space of coarse detection of conflicts of optimistic concurrency control protocol.

  • Timestamp based optimistic concurrency control

    Quazi Ehsanul Kabir Mamun, Hidenori Nakazato

    TENCON 2005 - 2005 IEEE REGION 10 CONFERENCE, VOLS 1-5   D3-04.1   2551 - +  2006  [Refereed]

     View Summary

    Optimistic Concurrency control demonstrates a few improvements over pessimistic concurrency controls like two-phase locking protocol or time-stamp based protocol. But the price of coarse detection of conflicts may sometimes be high and consequently discounts the advantage of optimistic concurrency control protocol. In this paper we have reduced the space of coarse detection of conflicts of optimistic concurrency control protocol.

  • Performance Study on DERACS: A Traffic Control Scheme for Video Multicast

    Jun Nishioka, Yoichiro Miyake, Hidenori Nakazato, Hideyoshi Tominaga

    GLOBECOM 2006 - 2006 IEEE GLOBAL TELECOMMUNICATIONS CONFERENCE   J89-B ( 8 ) 1453 - 1463  2006  [Refereed]

     View Summary

    QoS control for multicast over the Internet is necessary to provide high quality multicast video streaming. With existing DiffServ multicast schemes, multicast traffic in a DiffServ domain increases as the multicast-group membership grows, and consequently packets guaranteed for delivery may be discarded. Since it is hard to guarantee QoS for all flows over the entire network, we propose DERACS a delivery range control scheme which guarantees QoS in a limited delivery range formed by actively discarding packets. In this paper, we show the delivery range of DERACS through simulation and analysis.

  • Proxy Based Two Phase Commit with Wait for Improved Response Time and Blocking Probability

    Quazi Ehsanul Kabir mamun, Hidenori Nakazato

    roc. of the 17th IASTED International Conference Parallel and Distributed Computing and Systems     361 - 366  2005.11

  • Proxy Based Two Phase Commit with Wait for Improved Response Time and Blocking Probability

    Quazi Ehsanul Kabir mamun, Hidenori Nakazato

    roc. of the 17th IASTED International Conference Parallel and Distributed Computing and Systems     361 - 366  2005.11

  • A model for time-varying quality of speech services

    Z Chen, H Nakazato

    GLOBECOM '05: IEEE Global Telecommunications Conference, Vols 1-6   GC07-2   240 - 244  2005  [Refereed]

     View Summary

    Speech services are widely deployed on new communication infrastructures. However, compared with traditional infrastructures, the ever varying conditions are native of these new infrastructures. Modeling the time-varying speech quality becomes an urgent issue. This paper proposes a computable model for time-varying speech quality evaluation, called M-Model. Considering the time-varying issue, EWMA is used in the model. M-Model is validated by a subjective experiment. The model indicates that time-varying quality with extremely high frequency will not affect perceived quality at all. In addition, we observed that the recency effect influences not only the perceived overall quality but also the perceived instantaneous quality.

  • A model for time-varying quality of speech services

    Z Chen, H Nakazato

    GLOBECOM '05: IEEE Global Telecommunications Conference, Vols 1-6   GC07-2   240 - 244  2005

     View Summary

    Speech services are widely deployed on new communication infrastructures. However, compared with traditional infrastructures, the ever varying conditions are native of these new infrastructures. Modeling the time-varying speech quality becomes an urgent issue. This paper proposes a computable model for time-varying speech quality evaluation, called M-Model. Considering the time-varying issue, EWMA is used in the model. M-Model is validated by a subjective experiment. The model indicates that time-varying quality with extremely high frequency will not affect perceived quality at all. In addition, we observed that the recency effect influences not only the perceived overall quality but also the perceived instantaneous quality.

  • An approximation analysis for nonpreemptive EDF scheduling

    Masaki HANADA, Hidenori NAKAZATO

    IEICE Transactions on Communications   J87-A ( 12 ) 1518 - 1527  2004.12

  • 非割込み型EDF スケジューリングの近似解析

    花田真樹, 中里秀則

    電子情報通信学会論文誌   J87-A ( 12 ) 1518 - 1527  2004.12

  • P2P live streaming system with low signal interruption

    T Hama, K Asatani, H Nakazato, H Tominaga

    18TH INTERNATIONAL CONFERENCE ON ADVANCED INFORMATION NETWORKING AND APPLICATIONS, VOL 1 (LONG PAPERS), PROCEEDINGS     605 - 610  2004  [Refereed]

     View Summary

    P2P content distribution networks are collecting interest to efficiently deliver rich contents such as audio and video. Stream interruption caused by relay peers dropping out of the P2P network is a problem in P2P live streaming systems. In this paper we propose a P2P live streaming system with low stream interruption. In the proposed system, peers are connected to the peers with low drop-out probability and a wide and short P2P network is constructed. Also, multiple paths to the source is considered. We show the improvement in the interruption time by our algorithm through simulations.

  • P2P live streaming system with low signal interruption

    T Hama, K Asatani, H Nakazato, H Tominaga

    18TH INTERNATIONAL CONFERENCE ON ADVANCED INFORMATION NETWORKING AND APPLICATIONS, VOL 1 (LONG PAPERS), PROCEEDINGS     605 - 610  2004  [Refereed]

     View Summary

    P2P content distribution networks are collecting interest to efficiently deliver rich contents such as audio and video. Stream interruption caused by relay peers dropping out of the P2P network is a problem in P2P live streaming systems. In this paper we propose a P2P live streaming system with low stream interruption. In the proposed system, peers are connected to the peers with low drop-out probability and a wide and short P2P network is constructed. Also, multiple paths to the source is considered. We show the improvement in the interruption time by our algorithm through simulations.

  • Network load measurement for stream data

    D Ikegami, H Nakazato, K Asatani, H Tominaga

    2004 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS, VOLS 1-7   QS01-5   1862 - 1866  2004  [Refereed]

     View Summary

    The demand to access multimedia data such as live video is increasing due to the spread of broadband access network. However, the Internet only provides so called best-effort service. The network condition of the Internet shows fluctuation. Delivering video without any control causes degradation of the final video quality. To avoid such degradation, we must control video traffic to adapt to the fluctuating available bandwidth. In this paper, we propose a technique to find available bandwidth for end-to-end stream connections over the Internet. We claim that the correlation coefficient of network delay of an end-to-end stream is closely related to the bottleneck-link load for the end-to-end stream connection. We show and prove the relationship through analysis and simulations.

  • Network load measurement for stream data

    D Ikegami, H Nakazato, K Asatani, H Tominaga

    2004 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS, VOLS 1-7   QS01-5   1862 - 1866  2004

     View Summary

    The demand to access multimedia data such as live video is increasing due to the spread of broadband access network. However, the Internet only provides so called best-effort service. The network condition of the Internet shows fluctuation. Delivering video without any control causes degradation of the final video quality. To avoid such degradation, we must control video traffic to adapt to the fluctuating available bandwidth. In this paper, we propose a technique to find available bandwidth for end-to-end stream connections over the Internet. We claim that the correlation coefficient of network delay of an end-to-end stream is closely related to the bottleneck-link load for the end-to-end stream connection. We show and prove the relationship through analysis and simulations.

  • Rate control on correlation coefficient of network delay

    D Ikegami, H Nakazato, K Asatani, H Tominaga

    GLOBECOM'03: IEEE GLOBAL TELECOMMUNICATIONS CONFERENCE, VOLS 1-7   NG15_4   3118 - 3122  2003  [Refereed]

     View Summary

    The demand to access multimedia data such as live video is increasing due to the spread of broadband access network. However, the Internet only provides so called best-effort service. The network condition of the Internet shows fluctuation. Delivering video without any control causes degradation of the final video quality. In this paper we propose a stream-rate control algorithm RC3 that uses correlation of network delay to evaluate available bandwidth. We show performance of RC3 derived from simulations.

  • Rate control on correlation coefficient of network delay

    D Ikegami, H Nakazato, K Asatani, H Tominaga

    GLOBECOM'03: IEEE GLOBAL TELECOMMUNICATIONS CONFERENCE, VOLS 1-7   NG15_4   3118 - 3122  2003

     View Summary

    The demand to access multimedia data such as live video is increasing due to the spread of broadband access network. However, the Internet only provides so called best-effort service. The network condition of the Internet shows fluctuation. Delivering video without any control causes degradation of the final video quality. In this paper we propose a stream-rate control algorithm RC3 that uses correlation of network delay to evaluate available bandwidth. We show performance of RC3 derived from simulations.

  • TCP上のストリーム配信におけるレート制御方式の検討

    電子情報通信学会技術研究会報告   NS2001-229  2002.03

  • 分散透過デバッガの開発

    情報処理学会プログラミング研究会    2002.01

  • ネットワーク負荷測定を用いたストリーミングデータのレート制御方式

    電子情報通信学会 技術研究会報告   IN2001-144  2002.01

  • service differentiationを実現するためのパケットスケジューリング方式EWRRの性能評価と検証

    電子情報通信学会技術研究報告   NS2001-98  2001.09

  • Personalized Policy Management Architecture in Distributed Network

    Proc. of the 7th Asia-Pacific Conference on Communications    2001.09

  • 多段キュースケジューリングが可能なネットワークシミュレータの作成

    電子情報通信学会 2001年総合大会講演論文集   通信2,B-7-92  2001.03

  • ユーザ指向アクティブルーティングの提案

    電子情報通信学会 2001年総合大会講演論文集   通信2, B-11-12  2001.03

  • Diffserv網におけるマルチキャストセッションのためのアドミッション制御方法

    電子情報通信学会 2001年総合大会講演論文集   通信2,B-7-138  2001.03

  • Diffserv AFサービスを利用した階層化マルチキャストの検討

    電子情報通信学会 2001年総合大会講演論文集   通信2,B-7-142  2001.03

  • Diffserv網におけるトランスコーダを用いたマルチキャスト映像配信に関する検討

    電子情報通信学会 2001年総合大会講演論文集   通信2,B-7-141  2001.03

  • オブジェクトパッケージ化による分散実行環境の構築

    電子情報通信学会 2001年総合大会講演論文集   情報・システム1,D-3-4  2001.03

  • 分散透過デバッガの開発

    電子情報通信学会 2001年総合大会講演論文集   情報・システム1,D-3-5  2001.03

  • 光波長多重技術を活用したIPネットワークの課題

    電子情報通信学会 技術研究報告   IN2000-132  2000.11

  • Design of reconfigurable lightpaths in IP over WDM networks

    H Harai, F Kubota, H Nakazato

    IEICE TRANSACTIONS ON COMMUNICATIONS   E83B ( 10 ) 2234 - 2244  2000.10  [Refereed]

     View Summary

    The forwarding speed of IP routers must grow to accommodate the skyrocketing amount of traffic on the Internet. MPLS, which relies on the high processing power of lower layers, is a solution and it is under developing. On the other hand, a WDM network has been expected as a high-speed network, but it is also called a stupid network because of lacking its traffic granularity In order to bridge between these two layers, an IP over WDM network by a concept of MPLS has been proposed. This network has a potential to effectively use large transmission capacity provided by WDM technology. In this paper, we design IP over WDM networks that reconfigure IP routing and lightpaths each day or month. We formulate a problem that maximizes the network throughput based on integer linear programming. Through numerical examples, we show that the increase of the network throughput in IP over WDM networks is larger than that of IP networks. We also show the area where this method is applicable to the reconfigurable network.

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Misc

  • System Wide Information Management(SWIM)ネットワークモデルでのQoS実装

    中里秀則, ONGKASAE Kiratipong, 古賀禎, 呂暁東

    電子航法研究所研究発表会講演概要   15th  2015

    J-GLOBAL

  • An Efficient File Transfer Using Helper Peer in BitTorrent

    LEE Gilhyon, KANEMITSU Hidehiro, NAKAZATO Hidenori

    IEICE technical report. Communication systems   113 ( 295 ) 81 - 86  2013.11

     View Summary

    The Internet is often used to transfer large amount of data due to development of P2P (Peer-to-Peer) technology. BitTorrent is a most popular hybrid P2P application. BitTorrent splits one large file into a number of small pieces and shares the fragments of the file in the swarm. When there is small number of peers in the swarm, the performance of file sharing is not high. In this paper, we propose a method to utilize helper peers on the BitTorrent system in order to improve the file sharing efficiency. We evaluate the efficiency of the proposed method by using simulation.

    CiNii

  • Backup Topology Design for IP Fast Rerouting considering Double-Link Failures

    KAMAMURA Shohei, SHIMAZAKI Daisaku, HIRAMATSU Atsushi, NAKAZATO Hidenori

    IEICE technical report   112 ( 85 ) 37 - 42  2012.06

     View Summary

    This paper proposes backup topologies design algorithm for IP fast rerouting considering double-link failures. In the IP fast rerouting framework, each router has the set of backup topologies, and then it performs the local repairing using proper backup topology, which avoids failed point. Recovering from the concurrent double failures is realized by preparing the set of backup topologies, which protects arbitrary double links. However, this strategy increases the number of required backup topologies, and then it consumes the memory resources on an IP router. This paper focuses on the fact that backup routes can be provided by combining the routes of backup topologies. Then we propose a novel algorithm for reducing the number of backup topologies by considering the similarity between the original topology and backup topologies.

    CiNii

Industrial Property Rights

  • 辞書検索方法、装置、およびプログラム

    戸川 望, 島﨑 健太, 多和田 雅師, 津田 俊隆, 中里 秀則

    Patent

  • コンテンツ配信装置、システム、及び方法

    中里 秀則

    Patent

  • 故障復旧システムおよびノード

    5748147

    中里 秀則, 鎌村 星平

    Patent

  • 故障復旧システム、ノード、故障復旧方法およびプログラム

    5697211

    鎌村 星平, 中里 秀則

    Patent

  • ユーザ同定システム、ユーザ同定サーバ、携帯機器、ユーザ同定プログラム及び携帯機器のプログラム

    中里 秀則

    Patent

Awards

  • 電子情報通信学会フェロー

    2018.03  

  • 電子情報通信学会通信方式研究会委員長賞

    2013.07  

Research Projects

  • 大規模情報指向ネットワークにおける情報取得経路探索に関する研究

    Project Year :

    2019.04
    -
    2022.03
     

     View Summary

    情報指向ネットワーク(ICN)が扱うことを求められる大量のコンテンツについて、コンテンツを要求するパケットを、指定されたコンテンツの提供元であるサーバあるいはそれを一時記憶するネットワーク内のルータまで配送するための経路を決定する手法について研究する。ICNでは、コンテンツがルータに一時記憶されるため、要求パケットの配送先には、本来の提供元に加えて、当該コンテンツを一時記憶したルータも含まれる。そのためコンテンツ要求パケットの配送を容易にするための、コンテンツ一時記憶方式も本研究の対象に含む。要求パケットを、途中のルータで逐次経路解決を行い、最終的に宛先のコンテンツに配送する

  • IoT 機器増大に対応した有無線最適制御型電波有効利用基盤技術の研究開発 課題ア 有無線ネットワーク仮想化の自動制御技術

    総務省 

    Project Year :

    2017.04
    -
    2021.03
     

  • 映像情報の動機によるネットワーク内一時記憶の消滅に関する研究

    電気通信普及財団  研究調査助成

    Project Year :

    2017.04
    -
    2019.03
     

  • Green Information Centric Networks and Applications

    Project Year :

    2014.04
    -
    2017.03
     

  • Optimal Encoding Node Placement for Network Coding

    Project Year :

    2012.04
    -
    2015.03
     

     View Summary

    Encoding data at all nodes in a network can maximize data transmission efficiency. Encoding consumes processing power of routers, however. In this research, we investigated the placement of encoding nodes in a part of network nodes and data transmission strategies in such a network while achieving the comparable data transmission efficiency to the one in encoding at every node. We first identified that the reason of data-transfer efficiency improvement resides in the redundancy which help us to avoid duplicated data transmission. We also proposed a encoding-node placement algorithms exploiting indices that expresses features of network topologies and succeeded in improving data transmission efficiency effectively

  • 監視情報のアシュアランスネットワークに関する研究

    Project Year :

    2013
    -
     
     

  • 多重障害を考慮した高信頼故障回復技術の研究

    Project Year :

    2011
    -
    2012
     

  • 組み込み機器バックオフィスに関する研究開発

    Project Year :

    2008
    -
    2011
     

  • 医療情報を扱うクラウド化事業におけるセキュリティ対策の研究

    Project Year :

    2007
    -
     
     

  • 情報検索およびホームネットワークプラットフォームの研究

    Project Year :

    2004
    -
    2007
     

  • Research on Server Join/Leave Mechanisms

    Project Year :

    2003
    -
    2004
     

  • Development of QoS routing Simulation Software

    Project Year :

    2001
    -
     
     

  • Stream Information Delivery

    Project Year :

    2000
    -
     
     

  • QoS Control for Stream Communication Using Active Network

    Project Year :

    2000
    -
     
     

  • Development of QoS Simulation Software

    Project Year :

    2000
    -
     
     

  • Estimation of Temporal Behavior in Distributed Systems

     View Summary

    We proposed a network architecture for soft-real-time distributed systems. In the architecture, priority scheduling with fixed number of discrete priority levels available in VLAN header in Ethernet packets are used in LAN section of the network. Packet scheduling in WAN section of the network and processor scheduling adopt EDF scheduling. We proposed a priority assignment algorithm for LAN section based on delay constraint in one-hop LAN section which is determined from delay allocation to WAN section and processors, and on distribution of packet priority assignment in LAN section. As processor scheduling, we analytically derived estimation method for response time in EDF scheduling. We also proposed a packet scheduling algorithm called ORC-GPS for WAN section. The algorithm can utilize network efficiently while controlling delay. ORC-GPS provides larger schedulable region than both EDF and GPS. ORC-GPS is a class-based scheduling algorithm. Parameters for scheduling are determined on required maximum delays for classes. Since delay control by priority assignment in LAN section has only limited effect and we cannot vary delay from certain value, delay is mainly controlled in WAN section while delay control by priority classis performed in LAN section. ORC-GPS can be applied to this WAN section delay control. ORC-GPS parameters are determined from the residual delay derived by subtracting delay in LAN section from overall permissible network delay. In this way, the target end-to-end delay canbe realized

  • Study on Parallel Data Transmission for Peer-to-Peer Grid

     View Summary

    This research is concerned with data transmission method for computer-grid applications that are executed in peer-to-peer grid environment(P2P Grid) and require transmission of large amount of data. A P2P Grid is a distributed system that is made of a peer-to-peer network composed of remote personal computers(PCs) mutually connected by networks. We proposed a speed-up method for data transmission by setting up multiple TCP sessions between two nodes and letting the sessions cooperate. Also we studied another speed-up method by utilizing BitTorrent-like parallel transmission. In addition, a method to improve data transmission efficiency by utilizing data encoding in order to use bottleneck communication link efficiently is considered.By utilizing the results of this research, we can apply P2P grid computing to data processing that requires transmission of large data

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Specific Research

  • 超大容量分散コンテンツ名解決システムに関 する研究

    2018  

     View Summary

    本研究課題では、コンテンツ指向ネットワークにいて、一時記憶に保持されるコンテンツに対して、コンテンツ要求パケットを転送するための経路決定方法について検討を行った。コンテンツ名に加えて、コンテンツから求めたハッシュ値を探索に利用する。各ルータには「ハッシュ経路表」を備える。また、コンテンツ要求パケットには、コンテンツ名とハッシュ値を記述し、ルータのハッシュ経路表を利用して要求パケットの経路を決定する。さらに、このハッシュ経路表を基に、コンテンツの一時記憶への配置も行うことにより、一時記憶されたコンテンツの発見を実現させた。

  • 映像情報の同期による ネットワーク内一時記憶の削減に関する研究

    2016  

     View Summary

    現在検討が進められているコンテンツ指向ネットワークでは、ネットワーク上を流通するコンテンツを途中のルータで一時記憶することが可能である。しかし、ルータが備える一時記憶のメモリ量は限られるので、一つのコンテンツが占有するメモリ量はできるだけ小さくする必要がある。特にデータ量の大きいビデオデータについて、ルータで一時記憶する場合のメモリ占有量を削減することは有効性が大きい。そこで、ビデオ配信プロトコルであるRTCPにおいて、ビデオ再生タイミングを意図的にずらし、同一ビデオの視聴タイミングを同期させることにより、ビデオコンテンツの記憶時間を短縮し、占有する記憶容量を削減する方法について提案した。

  • 家庭内情報システムにおける空間情報の活用に関する研究

    2007  

     View Summary

    位置情報を考慮した設定不要の通信機能に関する検討として、おのおのの情報家電機器がもつ意味的な情報(例えば、電灯、窓の近くにある、など)を宛先としてパケットを転送するための経路制御方式について検討を行った。一般にパケット転送を行う各ルータは、それぞれが保持するルーティングテーブルを元にパケットの転送を行う。このルーティングテーブルのエントリにブルームフィルタを用いた。ここで検討している家庭内情報システムにおける通信形態は、各情報家電機器が、受け取ったパケットをさらに隣接の機器に転送することによって、エンド・ツー・エンドの通信が可能になるアドホック通信を仮定しているため、各機器がルータの役割を果たすことになる。具体的なルーティングテーブルの設定は、以下のようになる。それぞれの機器は、隣接の機器から受け取ったブルームフィルタを当該機器へ転送する条件のエントリとしてルーティングテーブルに保存する。ルーティングテーブルに保存したすべてのブルームフィルタとその機器自身の意味情報から生成したブルームフィルタのビットORを取った値の内、ランダムな1ビットを0に設定したものを、一定の周期で隣接の機器に転送する。ただし、このとき転送先の機器から受け取ったブルームフィルタはビットORを取るブルームフィルタに含めない。パケットには宛先情報として、宛先に該当する意味情報のブルームフィルタをパケットに記入する。上記のようにルーティングテーブルが設定されている状態で、パケットを受け取った各機器は、パケットのブルームフィルタとルーティングテーブルのブルームフィルタを比較し、一定の基準で一致する機器にパケットを転送する。以上のアルゴリズムによってパケット転送を行うと、70%程度の精度でパケットの転送が行われることが確認できた。

  • 汎用GRIDサービスのための自律的資源割り当ておよびスケジュール法の研究

    2006  

     View Summary

    ここで検討したGRIDは、ピアツーピア(P2P)システム上に構築することを前提としている。第1の成果として、P2Pネットワーク上で汎用GRIDを構築する場合の、ジョブ受付に係わる構成をまとめた。ジョブの受付は2段階で行う。まず実行するジョブを受け取ったピアは、そのジョブをどのピアで実行を開始するかを決定する。この判断基準としては、過去の履歴を元にしたBaysianネットワークを用いる手法を取ることとした。次にジョブ受付を割り当てられたピアは、ジョブのプログラムを分析して、並列実行可能な部分に分割する。分割されたプログラムと、観測した近隣ピアの計算資源(空きプロセッサ量、空きメモリ量、ネットワーク帯域など)を元に、各ピアに割り当てるプログラムを決定する。ピアへのプログラム割当は、与えられたジョブの実行時間を最小にすることを目標としている。分割されたプログラムをピアに割り当てる際の一つの基準として、当該プログラムを特定のピアで実行した時の実行時間を利用する。第2の成果はこの実行時間を推定するアルゴリズムであり、現在その評価を行っている。またGRIDを利用して実行するアプリケーションの一つの例としてComputer Graphicsのレンダリングを取り上げ、その分割手法も提案した。その提案が電子情報通信学会の総合大会で発表した論文である。レンダリングをステップに分解し、並列実行した場合の情報転送量を見積もり、プログラム分割方法と転送する情報を提案した。今後この分割手法を一つの参考として、プログラムの分割/割当アルゴリズムに改良を加えていく予定である。

  • Diffserv網リソースパラメータのリアルタイム適応制御に関する研究

    2002  

     View Summary

    Diffservネットワークでは、異なるQoSパラメータに対して要求条件が設定されたAssured ForwardingおよびExpedited Forwardingのサービスクラスが規定されているが、これらサービスクラスおよびベストエフォートクラスが共存した場合のQoS経路制御アルゴリズムを検討した。Expedited Forwardingは遅延を最小にするように、最短経路の中で、最もリンク使用率の低いものを割り当て、Assured Forwardingには、Expedited Forwardingの経路設定を妨げないように、最短経路の中でも最もリンク使用率の高い経路を設定するアルゴリズムを提案した。その有効性をシミュレーションによって評価し、2002年画像電子学会 第30回年次大会において発表した。パケットスケジューリングアルゴリズムDEWRRについて、各パラメータの設定とその設定に対する振る舞いの評価を行なった。DEWRRをDIffservのExpedited ForwardingおよびAssured Forwardingに適用する場合のパラメータ設定方法を提案し、その有効性をシミュレーションにより確認した。QoSを制御するために、エージェントを使ったQoS交渉システムとそのアプリケーションプログラムインタフェースを提案した。また、試作行い、提案システムが有効であることを実証した。この結果を2002年電子情報通信学会ソサイエティ大会において発表した。

  • 映像情報配送における通信品質制御のためのネットワーク運用管理方法の研究

    2001  

     View Summary

    1. トランスコーダを利用し、異なるネットワークドメイン間を繋ぐリンクにおいて、diffservのAF PHBおよびBest Effortクラスを使った場合について、マルチキャストグループ間での帯域配分方法を検討した。映像配信ではパケット損失による影響が大きいため、グループ毎にAF PHBを使うか、Best Effortクラスを使うかを区別することとし、またネットワークの混雑度を基に、Best Effortクラスの使用率を決定する方法を提案し、評価によりその有効性を確認した。2. アクティブネットワーク技術を用いたモーバイルエージェントによるネットワーク制御のためのアーキテクチャを提案し、実装を行なった。さらに、そのアーキテクチャ上でエージェント実行優先度を利用した通信品質制御方式の評価を行った。3. diffservに対応し、多様なスケジューリング方法、経路制御方法によるシミュレーションを可能にするネットワークシミュレータを一般に公開されているネットワークシミュレータであるns2をベースに開発した。また、輻輳制御機能を付加したdiffservのためのスケジューリング方式を提案し、開発したシミュレータを用いて、評価を行った。さらに、diffservサービスクラスを実現するための経路制御方式を提案し、この提案方式についても開発したシミュレータを用いた評価を行った。4. 映像情報配信の送信レート制御方式として、UDPを用いた場合とTCPを用いた場合それぞれについて制御方式を提案した。UDPの場合は、パケットの送信から受信までの遅延時間を基にネットワークの混雑度を推定し、その混雑度から送信レートを決定する制御する方式である。TCPの場合は、TCPがもともともつ送達保証機能を実現するための送信バッファの情報を使用する。送信バッファの使用状況から映像情報の送信レートを決定する方式を提案した。

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Syllabus

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