Faculty Profiles - FUNABIKI Nobuo

MISC - FUNABIKI Nobuo

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An extension of active access-point selection algorithm for throughput maximization in wireless mesh networks

Nobuo Funabiki, Junki Shimizu, Toru Nakanishi, Kan Watanabe, Shigeru Tomisato

Proceedings - 3rd IEEE International Conference on Intelligent Networking and Collaborative Systems, INCoS 2011 367 - 372 2011

Authorship：Lead author Language：English

In order to offer an inexpensive, scalable Internetaccess wireless network, we have studied the architecture, protocols, and design optimizations of the wireless Internet-access mesh network (WIMNET) that adopts multiple access-points (APs) connected by wireless links. WIMNET can improve the dependability to failures of links and/or APs by allocating APs redundantly in the network field. Because redundant APs may increase the operational cost and degrade the throughput due to increasing radio interferences, only the necessary APs for the connectivity between the hosts and the Internet gateway should be activated in communications. Previously, we have defined the active AP selection problem of selecting the minimum number of active APs, and proposed its heuristic algorithm. However, the throughput should be maximized in WIMNET as a bandlimited wireless network, even if the number of active APs is slightly increased. In this paper, we propose the extension of the active AP selection algorithm for the throughput maximization using the average hop count. We confirm the effectiveness of our algorithm extension through simulations in three instances, where the throughput is improved by about 10% with 7-14 additional active APs on average. © 2011 IEEE.

DOI： 10.1109/INCoS.2011.50

A throughput evaluation of wireless Internet-access mesh network using MIMO and adaptive array antenna

Shigeto Tajima, Nobuo Funabiki, Shigeru Tomisato, Masaharu Hata, Teruo Higashino

The 2011 International Workshop on Smart Info-Media System in Asia (SISA 2011) 79 - 84 2011

Automatic generation of configuration manuals for open-source software

Yukikazu Murakami, Erina Kagawa, Nobuo Funabiki

Proceedings of the International Conference on Complex, Intelligent and Software Intensive Systems, CISIS 2011 653 - 658 2011

Language：English

The installation and initial configuration of an open-source software can be difficult for novice users because of a common lack of adequate manuals. To address this problem, we have proposed a method of automatically generating Web based installation manuals for open-source software by editing the log information recorded during the installation process by a skilled user. A lot of systems using open-source software require changes of configuration files. Actually, middleware systems such as application servers and database management systems, often exhibit the low performance under their default configuration files. Thus, the optimization of such systems by setting the optimal confirmation is essential for significant performance improvements. In this paper, we propose the extension of our previous method to the automatic generation of Web-based configuration manuals. We verify the effectiveness of our proposal through experiments. © 2011 IEEE.

DOI： 10.1109/CISIS.2011.109

A proposal of fixed backoff-time switching method by link activation rate for wireless mesh networks

Shigeto Tajima, Nobuo Funabiki, Teruo Higashino

Proceedings of the International Conference on Complex, Intelligent and Software Intensive Systems, CISIS 2011 647 - 652 2011

Language：English

As an inexpensive and scalable access network to the Internet, we have extensively studied the Wireless Internet-access Mesh Network (WIMNET) that is composed of multiple access points (APs) connected through wireless links. Because most traffic in WIMNET passes through the gateway (GW) to the Internet, the links around the GW are much crowded so that they should be activated with higher priorities than others. In this paper, we propose the Fixed Back off-time Switching (CSMA-FBS) method for WIMNET using the CSMA/CA protocol to improve the performance by giving necessary activation chances to such links. Before starting communications, the target link activation rate and the active/passive back off-times for collision avoidance are calculated from the expected traffic load for each link. During communications, these back off-times are switched by comparing the actual link activation rate with the target one. By assigning different fixed values to these back off-times, the conflicts among the interfered links can be avoided. Through extensive simulations using two types of network topologies, we verify the effectiveness of our proposal. © 2011 IEEE.

DOI： 10.1109/CISIS.2011.108

A proposal of a menu planning algorithm for two-phase cooking by busy persons

Nobuo Funabiki, Shiho Taniguchi, Yukiko Matsushima, Toru Nakanishi

Proceedings of the International Conference on Complex, Intelligent and Software Intensive Systems, CISIS 2011 668 - 673 2011

Authorship：Lead author Language：English

For busy persons such as working people, students, and nurturing parents, it is very hard to spend a long time in cooking foods by themselves at home after working for long hours on weekdays. As one solution, the cooking process can be divided into two phases, where the preparation steps for foods that they will eat on the following weekdays are performed on a weekend, and the final steps for some foods are finished on the eating day in a short time. Then, the task of generating a menu planning with this two-phase cooking becomes a complex problem to satisfy the limited cooking time. In this paper, we formulate this time-constrained menu planning problem with the two-phase cooking, and prove the NP-completeness of its decision problem through the reduction from the NP-complete knapsack problem. Then, we present its heuristic algorithm based on a simple greedy method for the knapsack problem, where foods are sequentially selected into the menu in descending order of food priorities. We apply the algorithm to the generation of one week menu plan from 53 food candidates, where the result verifies the effectiveness of our approach. © 2011 IEEE.

DOI： 10.1109/CISIS.2011.112

A proposal of a traffic control method with consumed bandwidth estimation for real-time applications in wireless mesh networks

Sritrusta Sukaridhoto, Nobuo Funabiki, Toru Nakanishi

Proceedings of the International Symposium on Consumer Electronics, ISCE 143 - 148 2011

Language：English

As a flexible and cost effective solution for a scalable Internet-access network, we have studied the Wireless Internet-access Mesh NETwork (WIMNET) that is composed of multiple access points (APs). WIMNET utilizes multi-hop communications between APs to provide access to the Internet through a gateway (GW) from associated hosts, which becomes increasingly vulnerable to problems of the available bandwidth degradation and the network latency. As a result, real-time applications such as Voice-over-IP (VoIP) and video conferences are hard in WIMNET. In this paper, we propose a traffic control method with consumed bandwidth estimation to afford real-time applications in WIMNET. After the consumed bandwidth by the requesting applications is estimated, the least priority application is repeatedly dropped at GW using the leaky bucket traffic shaping, until it does not exceed the available bandwidth in WIMNET. The effectiveness of our proposal is verified through simulations using the QualNet simulator. © 2011 IEEE.

DOI： 10.1109/ISCE.2011.5973801

Minimal smart access-point selection for maximal throughput in wireless mesh networks

Nobuo Funabiki, Tatsuya Takebayashi, Toru Nakanishi

The International MultiConference of Engineers and Computer Scientists 2011 (IMECS 2011) 594 - 599 2011

無線メッシュネットワークでの動作アクセスポイント選択アルゴリズムの提案

清水淳基, 舩曵信生, 中西透

電子情報通信学会論文誌(B) J94-B ( 2 ) 264 - 273 2011

A proposal of a web-based computer-scored test assistance system for university education

Nobuo Funabiki, Hiroki Kawano, Toru Nakanishi, Kan Watanabe

Proceedings of the International Symposium on Consumer Electronics, ISCE 580 - 585 2011

Authorship：Lead author Language：English

Frequent applications of short tests or quizzes during classes can be effective to enhance educational effects to students in universities. However, teachers may have to spend much time to prepare test materials before classes, and mark the test papers from students after them. In this paper, in order to reduce these loads of teachers, we propose a Web-based computer-scored test assistance system that consists of the five functions for problem generation &amp
management, test generation &amp
management, grading, subject generation &amp
management, and learning profile management. By handling problems and tests separately where one test is composed of several problems, this system allows users to reuse existing problems and tests in various subjects by sharing them among teachers. Besides, by automatically generating test papers containing the randomly shuffled choices for each problem, it can prevent students from cheating by peeking at test papers of other students at neighbor seats. We implemented the system by extending our learning management system called NOBASU, and applied it to one class in our department, where the questionnaire result confirms the effectiveness of the system. © 2011 IEEE.

DOI： 10.1109/ISCE.2011.5973897

An implementation of a pairing-based anonymous credential system with constant complexity

Amang Sudarsono, Toru Nakanishi, Nobuo Funabiki

The International MultiConference of Engineers and Computer Scientists 2011 (IMECS 2011) 630 - 635 2011

A Proposal of Traffic Control Method with Bandwidth Usage Estimation for Real-Time Applications in Wireless Mesh Networks

SUKARIDHOTO Sritrusta, FUNABIKI Nobuo, NAKANISHI Toru

IEICE technical report 110 ( 339 ) 25 - 30 2010.12

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

As a flexible and cost effective solution for a large-scale Internet access network, we have studied the Wireless Internet-access Mesh NETwork (WIMNET) that is composed of multiple access points (APs). WIMNET utilizes multi-hop communications between APs to access to the Internet through a gateway (GW), which becomes increasingly vulnerable to the problems of the available bandwidth degradation and the network latency. As a result, real-time applications such as Voice-over-IP and Video conferences become hard to work in WIMNET. In this paper, we propose a traffic control method with a bandwidth usage estimation to afford real-time applications in WIMNET. After the consumed traffic is estimated, the least priority traffic is repeatedly dropped at GW using the leaky bucket traffic shaping, until it does not exceed the available bandwidth in WIMNET. The effectiveness of our proposal is verified through simulations using the QualNet simulator.

A Study of an Active Access-Point Selection Index for Throughput Maximization in Wireless Mesh Networks

SHIMIZU Junki, FUNABIKI Nobuo, NAKANISHI Toru

IEICE technical report 110 ( 339 ) 13 - 18 2010.12

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

The wireless Internet-access mesh network (WIMNET) has been studied to realize the inexpensive, scalable Internet-access network by 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, whereas redundant APs may cause the increase of the operational cost and the degradation of the throughput due to increasing radio interferences. Hence, we have formulated the active AP selection problem for selecting functioning APs for communications and proposed its heuristic algorithm. The simulation results indicate the existence of an active AP selection maximizing the throughput. In this paper, we present the average hop count and the traffic bias as the indices for this active AP selection with the maximum throughput. We verify their effectiveness through simulations in three instances.

An Application of the Web-Page Layout Optimization Method to Installation Manuals for Open Source Software

HORI Yuki, MURAKAMI Yukikazu, FUNABIKI Nobuo

IEICE technical report 110 ( 339 ) 215 - 218 2010.12

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

Recently, the Open Source Software (OSS) has become used at many places. However, the use of an OSS is hard for its novice users, because many OSSes have few good manuals. To solve this problem, we have proposed a method of automatically generating a web manual for installing an OSS by editing the log information recorded during the installation process by a skilled user. However, generated manuals have been designed to fit to the standard size. Many users often change a manual size to watch a manual and a terminal window together. When a manual size is small, the screen scroll operation is needed to look at the main content of the page. When the size is big, the blank space may also be large. In order to solve this problem, we applied to the web-page layout optimization method to proposed manuals.

A Proposal of Fixed Waiting Time Switching Method by Link Activation Rate in Wireless Mesh Networks

TAJIMA Shigeto, FUNABIKI Nobuo, HIGASHINO Teruo

IEICE technical report 110 ( 339 ) 137 - 142 2010.12

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

As an 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 which should be activated with higher priorities in WIMNET. In this paper, we propose the fixed waiting time switching method based on the CSMA/CA protocol (CSMA-FWS) to improve the performance of WIMNET. Before communications, the target link activation rate and the fixed waiting times for link activation/waiting are calculated from expected traffics of each link. During communications, these waiting times are switched by evaluating the link activation rate. Besides, by assigning different values to these waiting times among the links, the conflicts among interfered links are avoided. Through simulations using two types of network topologies, we verify the effectiveness of our proposal.

Ant Colony Optimization for the Node Placement Problem

OHKURA Keiichi, KATAYAMA Kengo, FUNABIKI Nobuo, MINAMIHARA Hideo, NISHIHARA Noritaka

IEICE technical report 110 ( 339 ) 173 - 178 2010.12

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

We address a problem of finding an optimal node placement that minimizes the amount of traffics reducing the weighted hop distances in multihop lightwave networks. The problem is called Node Placement Problem (NPP). For the NPP, several metaheuristic algorithms have been proposed so far such as genetic algorithm, tabu search, simulated annealing, iterated local search, and memetic algorithm. However, ant colony optimization (ACO) approach, one of the most representative metaheuristics, has not been presented for the NPP yet. In this paper we present an ACO algorithm incorporating k-swap local search (KLS) based on variable depth search for the NPP. To evaluate the performance of the ACO, we tested it on the benchmark problem instance of the NPP. We showed the performance of the ACO with KLS through comparisons with those of the iterated local search and the memetic algorithm that are known to be the highly effective metaheuristics for the NPP.

A Proposal of an Automatic Generation Method of Web-based Configuration Manuals for Open Source Software

KAGAWA Erina, MURAKAMI Yukikazu, FUNABIKI Nobuo

IEICE technical report 110 ( 339 ) 209 - 214 2010.12

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

Recently, Open Source Software (OSS) has become used at many places. However, the use of an OSS is hard for its novice users, because many OSSes have few good manuals. To solve this problem, we have proposed a method of automatically generating a web manual for installing an OSS by editing the log information recorded during the installation process by a skilled user. However, many OSS require to make changes the configuration file. In addition to that more systems are adopting OSS as middlewares such as application servers and DBMSs (Database Management Systems). For these OSS middlewares, it is known that even the processing performance is low under their default settings a great improvement is seen by optimizing their system setting. Therefore, in this research, aming at accumulation of system optimizing technology, an automatic generation of web-based configuration manual is proposed.

Extensions of Cooking Model for Cooking Step Optimization and Effects of Role Changes of Sub-Cook

MATSUSHIMA Yukiko, FUNABIKI Nobuo, NAKANISHI Toru

IEICE technical report 110 ( 301 ) 19 - 24 2010.11

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

In order to support homemade cooking of busy persons including working people, students, and child-growing families, we have proposed a cooking model to estimate the cooking time by simulating cooking steps by a main cook and a sub-cook who helps the main cook, and a cooking step scheduling algorithm using this model. In this paper, we propose extensions of the model by including additional two cooking steps, namely the nuke step and the mix step, so as to improve the accuracy of the estimated cooking time and the efficiency of the model. At the same time, we investigate effects in cooking time reductions by the increase of possible cooking steps to the sub-cook. The cooking experiment with six foods shows the improvement of the estimation accuracy, where the cooking time difference between the model and the actual cooking was about two minutes. The model calculations with various numbers of foods show that the cooking time can be reduced by the increase of possible cooking steps to the sub-cook.

Menu Selection and Bulk-Buying Ingredient Selection Algorithms for Home Cooking Support by Busy Persons

TANIGUCHI Shiho, FUNABIKI Nobuo, NAKANISHI Toru

IEICE technical report 110 ( 301 ) 25 - 30 2010.11

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

For busy persons such as working people and students, it is very important to reduce the time for buying ingredients and cooking foods after working for long hours on a weekday. As one solution to achieve it, they buy ingredients in bulk and finish the preparation steps of foods as the preparation phase on a weekend after planning the menus of the following weekdays. On a weekday, they only need to buy remaining ingredients and cook the finishing steps of the foods as the finishing phase that they will eat on the day, which can reduce the necessary time for home cooking. In this paper, we propose the menu planning algorithm and bulk-buying ingredient selection algorithm for this two-phase cooking. Because these problems can be reduced from the NP-complete knapsack problem, these algorithms are based on greedy methods for the knapsack problem. Through solving instances for these problems, we verify the effectiveness of the proposed algorithms.

Forward-Secure Group Signatures from Pairings

Toru Nakanishi, Yuta Hira, Nobuo Funabiki

IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES E93A ( 11 ) 2007 - 2016 2010.11

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

To reduce the damage of key exposures forward secure group signature schemes have been first proposed by Song In the forward secure schemes a secret key of a group member is updated by a one way function every interval and the previous secret key is erased Thus even if a secret key is exposed the signatures produced by the secret keys of previous Intervals remain secure Since the previous forward secure group signature schemes are based on the strong RSA assumption the signatures are longer than pairing based group signatures In addition the complexity of the key update or signing/verification is O(T) where T is the total number of Intervals In this paper a forward secure group signature scheme from pairings is proposed The complexity of our key update and signing/verification is O(log T)

DOI： 10.1587/transfun.E93.A.2007

A Minimum Smart Access-Point Allocation for Maximal Throughput in Scalable Wireless Mesh Networks

TAKEBAYASHI Tatsuya, FYNABIKI Nobuo, NAKANISHI Toru

IEICE technical report 110 ( 240 ) 69 - 74 2010.10

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

As 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 an expensive, PC-based smart AP (SAP) that can use multiple channels for wireless communications and has various functions for the Internet access. The other type is an inexpensive, commercial-based conventional AP (CAP) that can use only one channel. By adopting a small number of SAPs and a large number of CAPs, the large-scale WIMNET can achieve the bandwidth expansion and the cost reduction. In this paper, we propose a minimal SAP allocation algorithm for maximal throughput in WIMNET using our conventional SAP allocation algorithm. Our algorithm finds a solution that minimizes the reduction of the cost function when the number of SAPs increases. Through simulations in four instances, we show the effectiveness of our proposal.

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