Faculty Profiles - FUNABIKI Nobuo

MISC - FUNABIKI Nobuo

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A Study of Access-Point Allocation Algorithm for Scalable Wireless Mesh Networks in Indoor Environments

FARAG Tamer, FUNABIKI Nobuo, HASSAN Walaa

IEICE technical report 114 ( 252 ) 1 - 6 2014.10

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

Previously, we proposed an access-point (AP) allocation algorithm for scalable Wireless Internet-access Mesh NETwork (WIMNET) with multiple gateways (GWs) and the hop count limitation. The algorithm for K GWs consists of 1) the partition of the network field into K clusters by the K-means algorithm, 2) the sequential AP allocation in each cluster by our AP allocation algorithm for one GW, and 3) the simultaneous routing in K clusters by our routing algorithm considering multiple GWs and the hop count limitation. In this paper, we study the AP allocation algorithm in indoor environments as common fields for WIMNET. We assume that one wall drops the transmission speed by 15%, which is equivalent to 10m increase of the distance in an open space. To handle situations unsuitable to the K-means algorithm where plural GWs are closely located in neighboring rooms, we regard these GWs as one virtual GW, and apply 1) and 2) in the algorithm. Then, we apply 3) to the individual real GWs. We verify the effectiveness of our proposal through simulations in an indoor field using the WIMNET simulator.

A Consideration of Extended Wireless Internet-Access Mesh Network Simulator for MU-MIMO

TAJIMA Shigeto, FUNABIKI Nobuo, HIGASHINO Teruo

IEICE technical report 114 ( 252 ) 7 - 12 2014.10

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

Recently, IEEE802.11ac has been focused as a new high-speed wireless communication protocol. IEEE802.11ac adopts the frame aggregation that can reduce communication overheads by aggregating multiple frames into one big frame and the MU-MIMO (Multi-User Multi-Input-Multi-Output) that can improve the channel efficiency by allowing simultaneous transmissions to multiple destinations using the same channel. We have studied the efficient use of this protocol in the Wireless Internet-access Mesh NETwork (WIMNET) that provides an expandable Internet-access network by connecting multiple access-points through wireless links. In this paper, we present an extension of the WIMNET simulator that has been developed by our group in considering frame aggregation and MU-MIMO in IEEE802.11ac to evaluate the performance of WIMNET using this protocol. We evaluate the effect of MU-MIMO in WIMNET through simulations using the extended WIMNET simulator.

Robustness Evaluations of Cooking-Step Scheduling Algorithm under Operation Time Fluctuations

MATSUSHIMA Yukiko, FUNABIKI Nobuo

114 ( 222 ) 5 - 10 2014.9

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

To assist homemade cooking of busy people such as working people, child-growing families, and students, we have proposed a cooking-step scheduling algorithm for multiple dishes such that the total cooking time be minimized. For a given set of dishes where the cooking procedure for each dish is composed of a sequence of cooking-steps requiring certain time, this algorithm generates an optimal schedule for applying the cooking-steps of the dishes by considering the constraints of the cooks and the instruments. In this paper, we evaluate the robustness of this algorithm under time fluctuations in real cooking that can happen by variations of the proficiency of cooks and the cooking environment. First, we developed the evaluation cooking model to simulate the cooking process for a given schedule and time, and conducted simulations with randomly fluctuated time within 30% of the original one. Then, we actually cooked four dishes using the schedule found by the algorithm. In any result, the variation of the total cooking time is small compared to changes of cooking-step time. Thus, the robustness of the algorithm is confirmed.

BS-6-2 Throughput Measurements in Big Room with Different Access Point Locations for IEEE 802.11ac Wireless Networks(BS-6.Network and service Design, Control and Management)

CHEW Chang Choon, FUNABIKI Nobuo

Proceedings of the Society Conference of IEICE 2014 ( 2 ) "S - 38"-"S-39" 2014.9

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

The IEEE802.11ac wireless communication protocol has been introduced for high-speed wireless networks. In this paper, we provide throughput measurement results by Transmission Control Protocol (TCP) in a big room with various access point (AP) locations. Our measurement results show that TCP throughputs are greatly affected by AP locations for two-AP cases and are not affected for one-AP cases.

BS-6-1 AN EXTENSION OF ACCESS-POINT AGGREGATION ALGORITHM FOR HOST MOBILITY(BS-6.Network and service Design, Control and Management)

Islam Md Ezharu, Funabiki Nobuo

Proceedings of the Society Conference of IEICE 2014 ( 2 ) "S - 36"-"S-37" 2014.9

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

The AP aggregation algorithm has been proposed to reduce the number of active APs in overlapped WLANs by aggregating them to solve the problem of performance degradation due to interferences, and increased operational cost. However, this algorithm does not consider the mobility of hosts, although they usually join or leave the network randomly. In this paper, we propose an extension of the AP aggregation algorithm to deal with the mobility by considering the probability of each host to stay active. We verify the effectiveness of this extension through simulations using the WIM- NET simulator.

Efficient Proofs for Monotone Formulas on Attributes Excluding Restriction in Anonymous Credential System

SADIAH Shahidatul, NAKANISHI Toru, FUNABIKI Nobuo

Technical report of IEICE. ISEC 114 ( 203 ) 21 - 26 2014.9

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

An anonymous credential system on attributes allows a user to convince a service provider anonymously that he/she owns the certified attributes. Previously, we proposed an anonymous credential scheme to prove the satisfaction of a monotone formula when only one attribute is true for any OR relation. A monotone formula represents any combination of AND relations and OR relations. However, this system has a drawback that it cannot verify a user's certificate such that two or more attributes for an OR relation are true. In this paper, we propose an extended scheme for proofs of arbitrary monotone formula by adopting Linear Homonorphic (LH) signature scheme to generate a certificate that contains the minimum attribute set as required in the verification.

Robustness Evaluations of Cooking-Step Scheduling Algorithm under Operation Time Fluctuations

38 ( 36 ) 5 - 10 2014.9

Throughput Evaluations Using NS-2 for Access-Point Aggregation Algorithm in IEEE802.11n Wireless LANs

HASSAN Walaa, FUNABIKI Nobuo, ISLAM Md. EZHARUL, FARAG Tamer

IEICE technical report. Information networks 114 ( 110 ) 25 - 30 2014.6

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

The IEEE 802.11-based WiFi wireless technology has been commonly used in efficient wireless local area networks (WLANs). Recently, the IEEE 802.11n protocol among several ones has become popular as higher throughput operations with up to 600 Mbps. For a large-scale WLAN with multiple access-points (APs), we have proposed an access-point aggregation algorithm to minimize the operation cost while maximizing the performance. However, the effectiveness of this algorithm has been verified only through the WIMNET simulator that has been developed by our group as a simple network simulator. In this paper, we implement the modified 802.11n module that has been introduced by Wang and Wei on the NS-2 version 2.34, and evaluate the performance of this algorithm through simulations using it.

An Extension of Access Point Allocation Algorithm for Wireless Mesh Networks with Multiple Gateways and Maximum Hop Limitation

FARAG Tamer, FUNABIKI Nobuo, HASSAN Walaa

IEICE technical report. Information networks 114 ( 110 ) 31 - 36 2014.6

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

As an inexpensive, scalable Internet-access wireless network, we have studied design optimizations of a Wireless Internet-access Mesh NETwork (WIMNET) that adopts multiple access-points (APs) connected by Wireless Distribution System (WDS). In WIMNET, the proper allocation of APs is essential in ensuring the communication quality while reducing the installation and management costs. Thus, previously we proposed an AP allocation algorithm for WIMNET where only one gateway (GW) to the Internet exists and no hop limitation is imposed. In this study, we extend this algorithm for multiple GWs and the maximum hop limitation, which is common for large-scale WIMNET using WDS. First, for given K GWs, we partition the whole network into K sub-networks using the k-means algorithm such that the hosts in each sub-network connects with one GW. Then, we apply the previous AP allocation algorithm to each sub-network sequentially to allocate the APs. Finally, we apply our existing routing algorithm to obtain the routing path satisfying the hop limitation. We verify the effectiveness of this extended algorithm through simulations in one instance using the WIMNET simulator.

An Extension of Routing Algorithm for Wireless Mesh Networks Considering Frame Aggregation

TANI Yuma, FUNABIKI Nobuo, TAJIMA Shigeto

IEICE technical report. Information networks 114 ( 110 ) 19 - 24 2014.6

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

As a flexible inexpensive Internet-access network, we have studied the Wireless Internet-access Mesh NETwork (WIMNET) that is composed of wireless interconnected Access-Points (APs). We have proposed routing algorithm for WIMNET under realistic environments such as 1) multiple gateways, 2) communication speed changes, and 3) the limited number of hops. In this study, we extend the algorithm by considering the frame aggregation adopted in the IEEE802.11ac high-speed wireless communication protocol. We verify the effectiveness of our proposal through simulating three instances using the WIMNET simulator.

A Draft Coding Rule for Codes in Java Programming Learning Assistant System

ISHIHARA Nobuya, FUNABUKI Nobuo

IEICE technical report. Education technology 114 ( 82 ) 57 - 62 2014.6

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

We have developed the Java programming learning support system JPLAS as a Web application using JSP, Servlet, and Java Beans, to support repetitive self-learning of Java programming through automatic verifications of answers from students to assignments. Because the codes in JPLAS have been implemented by students who have newly joined our group and taken over the codes from seniors, their managements and updates have become complicated. At the same time, they do not follow the Web standard including HTML5 and CSS3 that has become popular to realize rich Web clients. In this paper, we propose a draft coding rule to implement codes in JPLAS following the Web standard. By adopting HTML5 and Ajax, this rule makes it possible implementing codes that can be easily maintained by avoiding redundancy.

An Extension of Fill-in-blank Problem Generation Algorithm for Java Programming Learning Assistant System

Tana, FUNABUKI Nobuo, ISHIHARA Nobuya, OGAWA Takuya

IEICE technical report. Education technology 114 ( 82 ) 63 - 68 2014.6

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

To help Java programming educations in universities and professional schools, we have developed a Web-based Java Programming Learning Assistant System (JPLAS). Since JPLAS provides the fill-in-blank problem function for Java novice students, we have proposed a graph-based fill-in-blank problem generation algorithm for it. In this paper, we extend this algorithm for blanking grammatically related words so as to encourage students studying the Java grammar more deeply. Besides, we evaluate generated problems with up to 20 blanks in a Java code where we have limited maximally 10 blanks previously. We applied problems by the extended algorithm to middle level students and found that the length, numbers of classes and methods, the difficulty of the implemented algorithm, and the existence of comments in the Java code have large influences on the correct solution rate.

An Implementation of Statement Fill-in-blank Problem Function for Java Programming Learning Assistant System

ISHIHARA Nobuya, FUNABIKI Nobuo, NAKANISHI Toru

IEICE technical report. Education technology 113 ( 482 ) 35 - 40 2014.3

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

We have proposed a Web-based JPLAS (Java Programming Learning Assistant System) to help students studying Java programming by themselves at home. By adopting the Test-Driven Development (TDD) method to verify the codes from students, JPLAS aims to reduce loads of teachers in addition to enhancing learning activities of students. In this paper, we propose and implement the statement fill-in-blank problem function in JPLAS as a trial assistance for code reading that has not been underestimated, although it is very important in studies of programming. In the statement fill-in-blank problem, a student is requested to fill a statement to the blank in a given Java code. By using a Program Dependence Graph (PDG), this function blanks an essential statement in the code. To evaluate our proposal, we generated multiple statement fill-in-blank problems using codes with similar procedures and applied them to students in a Java programming course in our department. Then, we found that the solution time of students decreased as they solved more problems.

A Difficulty Estimation Method of Fill-in-blank Problems for Java Programming Learning Assistant System

OGAWA Takuya, FUNABIKI Nobuo, NAKANISHI Toru, ISHIHARA Nobuya, NA Ta, AMANO Noriki

IEICE technical report. Education technology 113 ( 482 ) 41 - 46 2014.3

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

In our group, we have proposed a Web-based Java Programing Learning Assistant System (JPLAS) that helps students to study Java programing by themselves and the reduction of the burden on teacher. JPLAS has two kinds of blanks supplement (element fill-in-blank problem, statement fill-in-blank problem). These problems are applied to a student as a self-study problem in the classes of this school for Java programming abecedarians. In this thesis, after having enumerated indexes to estimate the difficulty of the problem that a teacher generated in JPLAS, we propose the index suitable for the difficulty estimate of each problem by performing the correlation analysis with the correct answer rate of each problem by the self-study result. We enable the presentation of the problem that a teacher accepted the level of the student by implementing difficulty estimation method of each fill-in-blank problem in JPLAS.

An Extension of Active Access Point Selection Algorithm Considering Practical Conditions for Wireless Mesh Networks

FUJITA Sho, FUNABIKI Nobuo, NAKANISHI Toru

IEICE technical report. Circuits and systems 113 ( 463 ) 35 - 40 2014.3

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

The wireless Internet-access mesh network (WIMNET) can realize an inexpensive flexible Internet-access network by using multiple access points (APs) connected by wireless links. For WIMNET with a single Internet Gateway (GW), we have proposed the active AP selection algorithm of selecting active APs from redundantly allocated APs for communications. However, in practical implementations of WIMNET, multiple GWs usually exist and the number of hops between a GW and a host is limited. Furthermore, the communication speed is dynamically changed by the link distance for the new high-speed communication protocol IEEE802.11ac. In this paper, we propose an extension of the active AP selection algorithm to consider these conditions. We verify the effectiveness of our proposal through simulations in four instances using the WIMNET simulator.

File Synchronization Performance using Bittorrent Sync in IEEE802.11ac Wireless Networks

KIM Bongsu, FUNABIKI Nobuo, NAKANISHI Toru

IEICE technical report. Circuits and systems 113 ( 463 ) 29 - 34 2014.3

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

Recently, Bittorrent Inc. has released a file synchronization software called Bittorrent Sync based on the peer-to-peer file sharing software Bittorrent. Using this software, users can synchronize the files on the designated folders across the multiple devices that are connected through the Internet without using a management server. These devices can be personal computers, smart phones, and tablets using different operating systems. To identify the folders to be synchronized, this software uses a 20-byte secret key that is randomly generated. We have considered the use of Bittorrent Sync to share files among nodes in a large wireless local area network (WLAN), where some nodes may be connected through mulithop wireless links. In this paper, we set up a simple WLAN test bed using the IEEE 802.1 lac protocol that has been recently introduced as a high-speed wireless communication protocol, and measure throughputs when various files with different sizes are synchronized among nodes using the software. Our results show that the throughput is quite high and stable, and a larger file can be transferred in a higher speed than a smaller file.

An Extension of Wireless Internet-Access Mesh Network Simulator for Frame Aggregation

TAJIMA Shigeto, FUNABIKI Nobuo, HIGASHINO Teruo

IEICE technical report. Circuits and systems 113 ( 463 ) 103 - 108 2014.3

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

The Wireless Internet-access Mesh NETwork (WIMNET) can provide an inexpensive, flexible, and expandable Internet-access network by connecting multiple access-points (APs) through wireless links. To improve the performance of WIMNET, it is important to adopt high-speed wireless communication protocols IEEE 802.11n/ac that have recently become available, for heavily crowded links between APs. As one of the technologies to enhance the communication speed, the frame aggregation has been introduced so that multiple frames can be sent at the same time to reduce the communication overhead. Because each link between APs usually handles packets to/from multiple hosts in WIMNET, the effect of the frame aggregation can be further enhanced. In this paper, we present a model of the frame aggregation and an extension of the WIMNET simulator based on the model, which has been developed by our group to evaluate the performance of WIMNET. Through simulations in simple topologies, we show the effectiveness of the frame aggregation, and the necessity of the proper number of aggregated frames and the aggregated routing path.

Throughput Measurements Using IEEE 802.11ac Devices for High-Speed Wireless Networks

CHEW Chang Choon, FUNABIKI Nobuo, NAKANISHI Toru

IEICE technical report. Circuits and systems 113 ( 463 ) 23 - 28 2014.3

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

Recently, IEEE802.11ac communication protocols have been introduced for high-speed wireless networks. Then, commercial devices implementing this protocol have been available from several vendors. In this paper, we provide various TCP throughput measurement results using devices from three vendors implementing this protocol under a set of TCP parameters in various conditions including one or two-hop communications, wall obstacle existences, different link distances, and the use of a repeater. Our measurement results show that TCP throughputs are greatly affected by vendors and communication conditions.

An Implementation of Moblie Anonymous Attribute Authentication System on Android Devices

IPSJ SIG Notes 2014 ( 45 ) 1 - 6 2014.2

Language：Japanese Publisher：Information Processing Society of Japan (IPSJ)

In current ID-based authentication systems, service providers can collect user's history via user's ID. On the other hand, service providers often want to authenticate user's attributes. To solve this problem, an anonymous attribute authentication system was proposed, where the user's attribtes are autheticated without revealing any information that can speciy the user. In this paper, we implemented a mobile anonymous attribute system using NFC and Bluetooth, where, by bringing the device close to another one, we can perform a direct anonymous attribute authentication. From the experiments on real devices, the execution time of anonymous attribute authentication is 0.98 seconds, and the total processing time including the connection establishment is 1.85 seconds.

A proposal of Web Browser-based Volunteer Computing Platform

Shogo Takaki, Kan Watanabe, Masaru Fukushi, Noriki Amano, Nobuo Funabiki, Toru Nakanishi

IPSJ SIG Notes 2014 ( 29 ) 1 - 8 2014.2

Language：Japanese Publisher：Information Processing Society of Japan (IPSJ)

In Volunteer Computing (VC) systems, volunteer participants can contribute their idle computing resources by computing a piece of the computation (job) in their idle time. In existing VC systems, participants must put an extra effort, e.g. installing a dedicated software to their computers and register their personal E-mail addresses, which will be barriers to join as a participant. This paper proposes a web-based VC platform, in which participants can join to VC system by just accessing a specified URL with Web browsers. By using LLVM techniques such as PNaCL, VC jobs become convertible as fast-acting Web applications. As the results of our experiments based on Himeno Benchmark, we show that the performance of PNaCl codes on a web browser is equivalent of native one.

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