Faculty Profiles - FUNABIKI Nobuo

MISC - FUNABIKI Nobuo

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Developments of the Node Configuration Problem for WDM Ring Networks

ISOGAI MEGUMI, FUNABIKI NOBUO, NAKANISHI TORU

2010 ( 3 ) 1 - 8 2010.9

An Extension of the Cooking Step Scheduling Algorithm for Various Dishes to Two Cooks

MATSUSHIMA Yukiko, FUNABIKI Nobuo, NAKANISHI Toru

IEICE technical report 110 ( 172 ) 19 - 24 2010.8

Language：Japanese Publisher：The Institute of Electronics, Information and Communication Engineers

The reduction of the cooking time with helps of partners, friends, and children is very important for busy persons. In this paper, we present the extension of the cooking step scheduling algorithm for various dishes to the case of two cooks, and the generalization of the cooking model for this extension by defining the state transition diagrams of dishes, pans and pots, a sink, stoves, and cooks, which have been proposed by our group. We implemented the algorithm as the Java application, and applied it to an instance of six dishes. The result confirmed the effectiveness of our proposal, where the case with two cooks reduced the cooking time by 16 minutes from the case with one cook.

Extensions of the Access Point Allocation Algorithm for Wireless Mesh Networks

Walaa Hassan, Nobuo Funabiki, Toru Nakanishi

IEICE TRANSACTIONS ON COMMUNICATIONS E93B ( 6 ) 1555 - 1565 2010.6

Authorship：Lead author Language：English Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

Previously, we have proposed an access point (AP) allocation algorithm in indoor environments for the Wireless Internet-access Mesh NETWork (WIMNET) using one gateway (GW) to the Internet. WIMNET consists of multiple APs that are connected wirelessly mainly by the Wireless Distribution System (WDS), to expand the coverage area inexpensively and flexibly In this paper, we present two extensions of this algorithm to enhance the applicability to the large-scale WIMNET. One is the multiple GW extension of the algorithm to increase the communication bandwidth with multiple GWs, where all the rooms in the network field are first partitioned into a set of disjoint GW clusters and then, our previous allocation algorithm is applied to each GW cluster sequentially. The APs in a GW cluster share the same GW. The other is the dependability extension to assure the network function by maintaining the connectivity and the host coverage, even if one link/AP fault occurs, where redundant APs are added to the AP allocation by our previous algorithm. The effectiveness of our proposal in terms of the number of APs and the throughput is verified through simulations using the WIMNET simulator.

DOI： 10.1587/transcom.E93.B.1555

A prioritized link activation method for access-point communications in wireless mesh networks

TAJIMA Shigeto, FUNABIKI Nobuo, HIGASHINO Teruo

IEICE technical report 110 ( 4 ) 47 - 52 2010.4

Language：Japanese Publisher：The Institute of Electronics, Information and Communication Engineers

As a flexible, inexpensive access network to the Internet, we have studied the Wireless Internet-access Mesh NETwork (WIMNET) that is composed of multiple access points (APs) connected with wireless links. Because most traffics pass through the gateway (GW) to the Internet, the links around the GW are crowded and can become bottlenecks in WIMNET. In this paper, we propose the prioritized link activation method based on the TDMA protocol to improve the performance of WIMNET. At each time slot, the links scheduled there are activated if they have packets. Then, other links are sequentially activated in descending order of priorities given by the traffics, if they have packets and do not cause interferences. Through simulations using two types of network topologies, we verify the effectiveness of our proposal.

A WDS Clustering Algorithm for Wireless Mesh Networks

Shigeto Tajima, Nobuo Funabiki, Teruo Higashino

IEICE TRANSACTIONS ON INFORMATION AND SYSTEMS E93D ( 4 ) 800 - 810 2010.4

Authorship：Lead author Language：English Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

Wireless mesh networks have been extensively studied as expandable. flexible. and inexpensive access networks to the Internet This paper focuses on one composed of multiple access points (APs) connected through multihop wireless communications mainly by the wireless distribution system (WDS) For scalability, the proper partition of APs into multiple WDS clusters is essential, because the number of APs in one cluster is hinted due to the increasing radio interference and control packets In this paper, we formulate this WDS clustering problem and prove the NP-completeness of its decision version through reduction from a known NP-complete problem Then we propose its heuristic algorithm. using a greedy method and a variable depth search method. to satisfy the complex constraints while optimizing the cost function We verify the effectiveness of our algorithm through extensive simulations. where the results confirm as superiority to the existing algorithm in terms of throughput.

DOI： 10.1587/transinf.E93.D.800

Test Code Assignment Function in Java Programming Education Support System Using Test-Driven Development Method

FUKUYAMA YUKI, FUNABIKI NOBUO, NAKANISHI TORU, AMANO NORIKI

2010 ( 21 ) 1 - 8 2010.2

A Proposal of the Active Access Point Selection Algorithm for Wireless Internet-access Mesh Networks

SHIMIZU Junki, FUNABIKI Nobuo, NAKANISHI Toru

IEICE technical report 109 ( 421 ) 7 - 12 2010.2

Language：Japanese Publisher：The Institute of Electronics, Information and Communication Engineers

As a scalable, inexpensive Internet-access network, we have studied the wireless Internet-access mesh network (WIMNET) that is composed of multiple access points (APs) connected by wireless links. WIMNET can improve the dependability to failures of links and APs by allocating APs redundantly. However, redundant APs may cause the increase of the operational cost and the degradation of the communication performance due to increasing radio wave interferences. In this paper, we formulate the active AP selection problem for selecting functioning APs for communications, and propose its algorithm. After finding the communication path using all the APs, our algorithm seeks the minimization of active APs by repeating the removal of one active AP and the check of the path existence. Through simulations using the WIMNET simulator, we show that our algorithm can reduce the number of active APs and there exists the best number of active APs in terms of the throughput.

Revocable Group Signature Schemes with Constant Costs for Signing and Verifying

Toru Nakanishi, Hiroki Fujii, Yuta Hira, Nobuo Funabiki

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES E93A ( 1 ) 50 - 62 2010.1

Language：English Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

Lots of revocable group signature schemes have been proposed so far. In one type of revocable schemes, signing and/or verifying algorithms have O(N) or O(R) complexity, where N is the group size and R is the number of revoked members. On the other hand, in Camenisch-Lysyanskaya scheme and the followers, signing and verifying algorithms have O(1) complexity. However, before signing, the updates of the secret key are required. The complexity is O(R) in the worst case. In this paper, we propose a revocable scheme with signing and verifying of O(1) complexity, where any update of secret key is not required. The compensation is the long public key of O(N). In addition, we extend it to the scheme with O( root N)-size public key, where signing and verifying have constant extra costs.

DOI： 10.1587/transfun.E93.A.50

Anonymous IEEE802.1X authentication system using group signatures

Amang Sudarsono, Toru Nakanishi, Yasuyuki Nogami, Nobuo Funabiki

Journal of Information Processing Society Japan 51 ( 3 ) 691 - 702 2010

A Node Aggregation Approach for WDM Ring Networks

Nobuo Funabiki, Toru Nakanishi, Megumi Isogai

TENCON 2010: 2010 IEEE REGION 10 CONFERENCE 829 - 834 2010

Authorship：Lead author Language：English Publisher：IEEE

For a high-speed metropolitan area network (MAN), a ring network based on the wavelength-division multiplexing (WDM) technology has been deployed to solve global information explosions in the Internet. To enhance the network performance, we have studied the node configuration problem, particularly for the one with the double-ring architecture where each node is equipped with fast-tunable transmitters and wavelength-fixed receivers (TT-FR) as fiber interfaces. In our studies, by adopting additional transmitters/receivers, nodes can afford far larger traffics than conventional ones. This fact indicates that plural nodes should be aggregated into one so that the transmitters/receivers can be utilized more efficiently. This paper presents a definition of the node aggregation problem for the WDM ring network and its simple greedy heuristic algorithm. The simulation results using the network simulator show the effectiveness of our approach.

DOI： 10.1109/TENCON.2010.5686576

An extension of the web-page layout optimization method for multimodal browsing sizes

Nobuo Funabiki, Junki Shimizu, Megumi Isogai, Toru Nakanishi

Proceedings - 13th International Conference on Network-Based Information Systems, NBiS 2010 139 - 146 2010

Authorship：Lead author Language：English

Recently, Web-page browsings at various terminals have become popular due to deployments of small mobile devices and large flat displays. To deal with this recent trend, we have proposed a Web-page layout optimization method for multimodal browsing sizes. It dynamically changes box locations and font sizes by switching CSS files for different browsing sizes, so that the main content can be accessed without the screen scroll operation even at a small size whereas the blank space is avoided at a large size. However, in this method, any box location must be specified by the absolute value in HTML/CSS files, which is not easy under a variety of browsing sizes. In this paper, we propose the extension of this method for flexible Web-page designs using the normal flow, the liquid layout, and the float property, where the browser automatically arranges the boxes. Using Ajax, the box location and the font size is switched to fit to the current browsing size by our method. The effectiveness of our proposal is verified through a usability test using sample Web-pages at small sizes. © 2010 IEEE.

DOI： 10.1109/NBiS.2010.18

Software architecture and characteristic functions in learning management system "NOBASU"

Nobuo Funabiki, Toru Nakanishi, Noriki Amano, Hiroki Kawano, Yuuki Fukuyama, Megumi Isogai

Proceedings - 2010 10th Annual International Symposium on Applications and the Internet, SAINT 2010 109 - 112 2010

Authorship：Lead author Language：English

Recently, a learning management system (LMS) using the Web technology has been used at many educational institutions. To support educational activities in our department, we have independently developed an LMS called NOBASU (NetwOrk-Based Assistant System for University education) to improve the quality while reducing costs. Besides conventional functions in LMS, NOBASU has incorporated several original ones such as the keyword submission function for preparing and reviewing class contents. In this paper, we present two new characteristic functions for the Java programming education in NOBASU. The Java code test function verifies the specifications in source codes from students using the test-driven development (TDD) method. The Java test code submission function requests students to submit test codes so that they can generate detailed program specifications by themselves. © 2010 IEEE.

DOI： 10.1109/SAINT.2010.24

A Proposal of a Smart Access Point Allocation Algorithm for Scalable Wireless Mesh Networks

Kanako Uemura, Nobuo Funabiki, Toru Nakanishi

INTERNATIONAL MULTICONFERENCE OF ENGINEERS AND COMPUTER SCIENTISTS (IMECS 2010), VOLS I-III 848 - 853 2010

Authorship：Lead author Language：English Publisher：INT ASSOC ENGINEERS-IAENG

As a flexible, inexpensive, and extensive Internet access network, we have studied WIMNET (Wireless Internet-access Mesh NETwork) composed of multiple access points (APs) as wireless mesh routers. WIMNET utilizes two types of APs to achieve the scalability with sufficient bandwidth while reducing costs. One is the expensive, programmable smart AP (SAP) that can use plural channels for wireless communications and has various functions for the Internet access. Another is the inexpensive, non-rogrammable conventional AP (CAP) that can use only one channel. To enhance the performance, the proper SAP allocation is critical, because the number of SAPs is much smaller than that of CAPs. In this paper, we present the definition of the SAP allocation problem, and its algorithm of extracting the optimum solution in terms of the newly defined cost function after finding the communication route configuration by applying our previous algorithms. We verify the effectiveness through simulations in three network topologies using the WIMNET simulator.

Software Architecture and New Functions in Learning Management System "NOBASU"

Nobuo Funabiki, Toru Nakanishi, Noriki Amano, Hiroki Kawano, Kanako Uemura

INTERNATIONAL MULTICONFERENCE OF ENGINEERS AND COMPUTER SCIENTISTS (IMECS 2010), VOLS I-III 665 - 670 2010

Authorship：Lead author Language：English Publisher：INT ASSOC ENGINEERS-IAENG

Recently, the learning management systems (LMS) using the Web technology has been developed and used at a lot of educational institutions. We have continuously developed an original LMS called NOBASU (NetwOrk-Based Assistant System for University education) to support various educational activities in our department to improve the quality while reducing costs. In this paper, we describe the software architecture and the outline of distinguishing functions in NOBASU. In addition to conventional functions in LMS, NOBASU has incorporated several original ones such as the keyword submission function for preparing and reviewing classes, the lecture-scene playback function using the digital picture-card show, and the writing style check function for report submissions. We have implemented them in NOBASU and evaluated the effectiveness through applications to real classes in our department.

A Proposal of a Cooking Order Optimization Algorithm of Various Menus

MATSUSHIM YUKIKO, FUNABIKI NOBUO, NAKANISHI TORU

2009 ( 13 ) 1 - 6 2009.12

Improvement of Dependable Access Point Allocation Algorithm and Introduction of Route Availability for Wireless Mesh Networks

HASSAN Walaa, FARAG Tamer, FUNABIKI Nobuo, NAKANISHI Toru

IEICE technical report 109 ( 326 ) 11 - 16 2009.12

Language：English Publisher：The Institute of Electronics, Information and Communication Engineers

As a scalable, flexible, and inexpensive network, we have studied the wireless Internet-access mesh network (WIMNET) that is composed of multiple access points (APs) connected by the wireless distribution system (WDS). Previously, we have proposed the AP allocation algorithm, and its dependability extensions such that one link fault or one AP fault does not impair the connectivity of the network. In this paper, we improve this heuristic algorithm by adding the improvement stage using the local search method. Besides, we introduce the route availability (RA) index to estimate the certainty of connections between hosts and the Internet gateway. We verify the effectiveness of our proposal through simulations in two instances.

A Proposal of Efficient Attribute-Based Group Signature Schemes Using Pairings

FUJII Hiroki, NAKANISHI Toru, FUNABIKI Nobuo

IEICE technical report 109 ( 271 ) 15 - 22 2009.11

Language：Japanese Publisher：The Institute of Electronics, Information and Communication Engineers

Group signature scheme is the digital signature scheme enhancing the privacy of the user, and efficient pairing-based schemes have been proposed. Recently, some attribute-based group signature schemes are proposed, where the signer's attributes can be verified. The attribute-group signature allows us to construct more complex groups, because it can prove the logical relation of attributes such as 'AND' and 'OR'. However, the previouse schemes, the number of pairings and exponentiations in signing and verification depends on the number of attributes. In this paper, we propose an efficient attribute-base group signature scheme, where the computational complexity doesn't depend on the number of attributes.

A Proposal of a Smart Access Point Allocation Algorithm for Scalable Wireless Mesh Networks

UEMURA Kanako, FUNABIKI Nobuo, NAKANISHI Toru

IEICE technical report 109 ( 228 ) 13 - 18 2009.10

Language：Japanese Publisher：The Institute of Electronics, Information and Communication Engineers

For a flexible and low-cost access network to the Internet, we have studied WIMNET (Wireless Internet-access Mesh NETwork) that is composed of multiple access points (APs) as wireless routers. WIMNET utilizes two types of APs to achieve the scalability and the communication bandwidth while reducing the cost. One type is the expensive, note-PC based smart AP (SAP) that can use multiple channels for wireless communications and has various functions for the Internet access. Another type is the inexpensive, commercial-based conventional AP (CAP) that can use only one channel. For the performance enhancement, the proper allocation of SAPs among APs is critical in WIMNET, because the number of SAPs is usually much smaller than that of CAPs. In this paper, we present the formulation of the SAP allocation problem for WIMNET and its heuristic algorithm. Our algorithm seeks the best SAP allocation in terms of the newly defined cost function, after finding the communication route by applying our previous algorithms. We verify the effectiveness of our proposal through simulations in three instances using the WIMNET simulator.

A node configuration algorithm with bandwidth bottleneck resolution for WDM ring networks

Megumi Isogai, Nobuo Funabiki, Toru Nakanishi, Yosuke Isshiki

PHOTONIC NETWORK COMMUNICATIONS 18 ( 2 ) 218 - 226 2009.10

Language：English Publisher：SPRINGER

The wavelength-division multiplexing (WDM) technology has been extensively studied and actually deployed as a key technology to solve global information explosions by multiplexing plural signal paths using different wavelengths into one optical fiber. Among WDM-based network architectures, this article focuses on a double-ring one for a next-generation metropolitan area network (MAN), where each node is normally equipped with two pairs of fast-tunable transmitters and wavelength-fixed receivers (TT-FR) as interface to two fibers. To enhance the network performance, additional transmitters/receivers at nodes and receiver wavelengths should be assigned optimally, so that the bandwidth bottleneck can be resolved both on nodes and fiber links. This article formulates this node configuration problem with bandwidth bottleneck resolution as a combinatorial optimization problem, and proves the NP-completeness of its decision version. Then, it presents the two-phase heuristic algorithm composed of a greedy method and a variable depth search (VDS) method. Our algorithm is evaluated through extensive network simulations, where the results support the effectiveness of this joint assignment approach.

DOI： 10.1007/s11107-009-0185-y

Improvement of Anonymous Authentication System Using Proxies and Its Application to an Anonymous Bulletin Board

YANO Masaya, NAKANISHI Toru, FUNABIKI Nobuo

IEICE technical report 109 ( 207 ) 45 - 50 2009.9

Language：Japanese Publisher：The Institute of Electronics, Information and Communication Engineers

Our research group has implemented the anonymous authentication system based on a group signature scheme for Web services. To avoid modifications of Web servers and browsers, this system uses proxies. However, the system has problems that the lack of the session management causes the communication delay, and that any application of the system has not been implemented, yet. In this study, we implemented the session management function and applied it to an anonymous bulletin board. The experimental results show that the communication time is reduced in a session due to the session management and that the anoymous bulletin board is available in practical time.

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