Computer Networks Laboratory

Sigaku Tei Professor	Hirokuni Kurokawa Associate Professor

Research Ubiquitous context-aware platform and algorithms Context-aware service is one of the most important researches in the field of ubiquitous networks. It detects user ’s 　context by using sensor networks, and provides adaptive personalized services to the user accordingly. In 2009, we were studying new methods for construction of context-aware platform. The new methods are based on composition of context. By composition of context, a complex situation can be identified by collecting small pieces of simple information, in order to provide proper service adaptive to such situation. We were trying to develop a two-stage composition method. The first stage is composition of the useful information to represent the situation for a single user. The second stage is composition of multiusers ’situation to provide services taking the relations of users into account. We tested the proposal in an indoor ubiquitous environment. The method and the experiment results were summarized and submitted to a Journal. Context-aware services are mainly provided based on the context information of a user. The context information generally consists of current time, location, favorites, and requests of the users. Since more than one users who have different favorites and requests may be in the same location at the same time, a service proper to a user may cause inconvenient or troubles of another user. In addition to the above mentioned composition based context-aware methods, we also studied a distributed algorithm based on game theory to detect and solve the troubles when providing context-aware services. The algorithm was presented in an international conference. Ubiquitous applications in e-learning Ubiquitous learning becomes a hot topic as one application field employing ubiquitous devices and sensors. A learner can learn from the real world by observing, touching, or manipulating real objects, and learning support can be provided by smart objects, such as stationeries, school-bags, desks, and chairs used in everyday life at proper time, place, and situation. In 2009, we continue the studies on ubiquitous learning applications. Firstly, we had developed an education system providing children a learning environment for dual experience of the safety knowledge.. The dual experience environment is constructed by a miniaturized world and a computerized world. Based on the developed system, we verified effectiveness of using the system through experimental results and the results were systematically analyzed with semantic differential and principle component analysis. The method and the analyzed results were summarized and submitted to a Journal. Secondly, we further continuously worked on ubiquitous-pet (u-pet) based education systems. Additional experiment was performed to show the effectiveness of the u-pet. Specially, u-pet is used for ubiquitous training applications, which are for acquiring skills and enhancing physical abilities through exercise and experience in the real world, as an important domain in u-learning. We create a ubiquitous pet (u-pet) as a metaphor of our system. A u-pet is always with the learner and encourage the leaner to start training at proper time and to do training smoothly. The u-pet can perform actions with the learner in training, change its own attributes based on the learner ’s attributes, and adjust its own learning rate by a learning function. The u-pet grasps the state of the learner and adopts different training support strategies to the learner ’s training based on the learner ’s short and long term states. The method and the experiment results were summarized and submitted to a Journal. Embedded system platform In order to satisfy the demands of industry for competent embedded system engineers, universities should improve their specialist education. We first analyzed the industry demands for the university education and multidisciplinary features of embedded system development, and proposed a new educational method called spirally tight-coupled step-by-step educational method. A learning process forms a spiral shape with learning rounds. Each learning round has three steps: lecture, demo, and hands-on practice, which are tight-coupled to enable students to timely revisit important knowledge. The next round is directly based on the current round to maintain a smooth learning curve. Since students can see the output of their work quickly and timely, it is helpful to keep the learning motivation. Though a learning round is performed in a short period, the core knowledge and skills can be repeated in different ways through the three kinds of educational steps, so that the students can master the usage of knowledge and skills. Moreover, personal ability is improved in the learning process. The method has been applied to a career development program for foreign students in Japan, supported by the Japanese government. Totally 26 students took this course. The students ’ achievement and performance shows that the proposed method can enable the students to master the knowledge and transform it into skills effectively. The method and the experiment results were summarized and submitted to a Journal. RIDEE(Realtime Interactive Distance Education Environment) This research focuses on the support of real-tiem and interactive distance education activities. One result of this research is a computer system, named RIDEE system. In 2009, the comunication control subsystem of RIDEE system has been redesigned to get the scalability in IPv4 environment especially private networks connected the Internet by NAT (Network Address Transfer) devices. In 2009, a experimental system has been developed which was used in several tests and useful result has been got for further research. Skill Evaluation Support for NPP Operator Training In Japan, more than 20 nuclear power plants(NPP) are in operation. To keep the safety of NPP, the ability for the operators to deal with dangerous case is very important. To get good skill in nuclear power plant operation, every operator is trained in a training center where is equipped with a full-mock simulator of nuclear power plant control room. In the training center, the operators learn how to control a nuclear reactor and how to deal with various warning or dangerous cases. Operator’s skill evaluation will be given by examinations based on scenarios of warning or dangerous cases. Currently, this kind of evaluation is done based on the subjective judgment of the instructors and the following training data: (1)Warning scenario and operation log in the examinations. (2)Video and audio recorded in the examinations. In order to get high level training, the next step of skill evaluation is quantitative evaluation including checking operator’s mental condition etc. This kind of evaluation needs more detail information about trainee’s operation and behavior. We proposed a way to get that information from the video in the training facilities. In 2009, an experimental system based image processing technology was designed for this research. Computer Programming Contest Support PC Kosien, a nationwide high school student personal computer programming contest, is an important educational activity organized by the University of Aizu. The goal of this research is to support the programming contest, not only for the contest players, but also for the spectators, especially providing services to the spectators; making them more exciting, giving them more enjoyment, so that they will have more interests in computer, programming, and our university. As the result, a programming contest management support system, PCSS, has been used in PC Kosien every year. A lot of functions were added to PCSS in 2009 fiscal year. Computer Programming Language Education Support C language is a major computer programming language, being widely used in software system development and education of computer science. However, comparing with other computer languages, C language is difficult and little interesting to its beginners and, therefore, it takes more time to learn or teach. To give those beginners an interesting and comprehensible way to learn C language, we proposed a technique to make C language program visible. By this technique, the change of program status such as variable value in each step can be displayed in a graphical way. A C language learning support system has been developed based on the above idea, In 2009 fiscal year,the system has been used in Open-lab and public lectures. Education Courses Members of our laboratory taught the following courses in AY2009. Undergraduate courses – Communication and Networks I – Communication and Networks II – Computer Languages – Programming Java (Only exercise class) Graduate courses Computer Communications and Networking (801) – Distributed Algorithms (808) – Fundamentals and Practices of Functional Safety Related Systems (964) – Ubiquitous network systems and its applications (956) – Fundamentals and Practices of High Quality and Safety-Critical Embedded Systems (963) - Creative Factory Seminars: Investigation of Safely and Quality Management in Companies and Experiencing Development of Systems/products though internship Supervising students 3 Ph.D students, 12 master students, 11 seniors did their research work in AY2009 in the laboratory, under the supervision of the professors in the lab. Theses 2 Masters and 9 seniors finished their theses in AY2009, and graduated, under the supervision of the professors in the laboratory. Aizu IT Nisshikan factory A factory for experiencing venture starting up is continued, as a part of Good Practice program supported by MEXT. Every week, there is an activity time, when the students discussed with professors and/of engineers in companies on how to develop new systems and product for business. Contribution to local region Professors of this laboratory helped for preparation and operation of U. Aizu Computer Science Summer Camp. Professor Aiguo He made big contribution to the PC KOSHIEN (PC contest sponsored by the Fukushima prefecture). Professors of this laboratory gave several off-campus lectures to students and teachers of high-schools, and citizens in the Fukushima prefecture).

Refereed Journal Papers

[z-cheng-01:2009]	Mizuo Kansen, Masaya Sasaki, Xianzhi Ye, Takanobu Watanabe, and Zixue Cheng. A Mobile-learning Supporting System Based on ARCS Theory Using LT/RW Method. Journal of Japan e-Learning Association (JeLA), 9:121–128, May 2009.
	In this paper, we propose a mobile-learning support system using LT/RW method. LT/RW method is a technique in order to grasp the learner’s understanding state for multiple-choice test in e-Learning. Using LT/RW method we are able to grasp the learner’s understanding state not only from judging if the answer is right or wrong but also from a relationship between the level of difficulty of each question and the level of understanding of each learner. And also we are able to grasp from a relationship between the amount of time that a particular learner takes to solve each question and the amount of time to do so in general.
[z-cheng-02:2009]	Ngoc T. Dang, Anh T. Pham, and Zixue Cheng Impact of GVD on the Performance of 2-D WH/TS OCDMA Systems Using Heterodyne Detection Receiver. IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences, E92-A(4):182–1191, Apr. 2009.
	In this paper, a novel model of Gaussian pulse propagation in optical fiber is proposed to comprehensively analyze the impact of Group Velocity Dispersion (GVD) on the performance of two-dimensional wavelength hopping/time spreading optical code division multiple access (2-D WH/TS OCDMA) systems. In addition, many noise and interferences, including multiple access interference (MAI), optical beating interference (OBI), and receiver’s noise are included in the analysis. Besides, we propose to use the heterodyne detection receiver so that the receiver’s sensitivity can be improved. Analytical results show that, under the impact of GVD, the number of supportable users is extremely decreased and the maximum transmission length (i.e. the length at which BER 10-9 can be maintained) is remarkably shortened in the case of normal single mode fiber (ITU-T G.652) is used. The main factor that limits the system performance is time skewing. In addition, we show how the impact of GVD is relieved by dispersion-shifted fiber (ITU-T G.653). For example, a system with 321 Gbit/s users can achieve a maximum transmission length of 111 km when transmitted optical power per bit is -5 dBm.
[z-cheng-03:2009]	Ngoc T. Dang, Anh T. Pham, and Zixue Cheng. Beat Noise Cancellation in 2-D OCDMA Systems using Optical Hard-limiter Array. IEICE Trans. on Communications, Special Section on Optical Access Technologies, E93-B(2):289–292, Feb. 2010.
	We analyze the beat noise cancellation in two-dimensional optical code-division multiple-access (2-D OCDMA) systems using an optical hard-limiter (OHL) array. The Gaussian shape of optical pulse is assumed and the impact of pulse propagation is considered. We also take into account the receiver noise and multiple access interference (MAI) in the analysis. The numerical results show that, when OHL array is employed, the system performance is greatly improved compared with the cases without OHL array. Also, parameters needed for practical system design are comprehensively analyzed.
[z-cheng-04:2009]	Xianzhi Ye, Lei Jing, Mizuo Kansen, Junbo Wang, Kaoru Ota, and Zixue Cheng. A Support Method with Changeable Training Strategies based on Mutual Adaptation between a Ubiquitous Pet and a Learner. IEICE Transactions on Information and Systems, E93-D(No.4), Apr. 2010.
	With the progress of ubiquitous technology, ubiquitous learning presents new opportunities to learners. Situations of a learner can be grasped through analyzing the learner’s actions collected by sensors, RF-IDs, or cameras in order to provide support at proper time, proper place, and proper situation. Training for acquiring skills and enhancing physical abilities through exercise and experience in the real world is an important domain in u-learning. A training program may last for several days and has one or more training units (exercises) for a day. A learner’s performance in a unit is considered as short term state. The performance in a series of units may change with patterns: progress, plateau, and decline. Long term state in a series of units is accumulatively computed based on short term states. In a learning/training program, it is necessary to apply different support strategies to adapt to different states of the learner. Adaptation in learning support is significant, because a learner loses his/her interests easily without adaptation. Systems with the adaptive support usually provide stimulators to a learner, and a learner can have a great motivation in learning at beginning. However, when the stimulators reach some levels, the learner may lose his/her motivation, because the long term state of the learner changes dynamically, which means a progress state may change to a plateau state or a decline state. In different long term learning states, different types of stimulators are needed. However, the stimulators and advice provided by the existing systems are monotonic without changeable support strategies. We propose a mutual adaptive support. The mutual adaptation means each of the system and the learner has their own states. On one hand, the system tries to change its state to adapt to the learner’s state for providing adaptive support. On the other hand, the learner can change its performance following the advice given based on the state of the system. We create a ubiquitous pet (u-pet) as a metaphor of our system. A u-pet is always with the learner and encourage the leaner to start training at proper time and to do training smoothly. The u-pet can perform actions with the learner in training, change its own attributes based on the learner’s attributes, and adjust its own learning rate by a learning function. The u-pet grasps the state of the learner and adopts different training support strategies to the learner’s training based on the learner’s short and long term states.
[z-cheng-05:2009]	Ngoc T. Dang, Anh T. Pham, and Zixue Cheng. Performance Analysis of Spectral Amplitude Encoding OCDM systems over the linear dispersive optical channel. IEEE/OSA Journal of Optical Communications and Networking, 1(no. 6):521–529, Nov. 2009.
	We propose a new model of pulse propagation over a linear dispersive optical channel and use this model to comprehensively analyze the performance of spectral amplitude encoding optical code-division multiplexing (SAE/OCDM) systems under the impact of group velocity dispersion (GVD). We quantitatively discuss the impact of GVD on various aspects of SAE/OCDM system performance, including the number of supportable users and the maximum transmission length and power penalty. We also investigate the system performance with several types of optical fibers, such as singlemode fiber (SMF), dispersion-shifted fiber (DSF), and nonzero DSF. In addition, we discuss techniques to compensate for GVD so that the performance of SAE/OCDM systems can be improved.

Refereed Proceeding Papers

[aiguo-01:2009]	Aiguo He and Tomohiro Ohdaira. A Case Study: File Access Privacy Control Using Filter Hook Driver. In Proceedings of the 2009 IEEE International Symposium on Parallel and Distributed Processing with Applications, pages 488–493, 2009.
	Sand-box security model is extremely useful for secure execution of untrusted applications. Many sand-box model based security systems proposed so far provide security by intercepting system calls invoked by applications and controlling their execution. However, a problem in existing sand-box based systems is the amount of overhead required for security checks performed after system call interception. In addition, it is difficult for computer novices to manage their Security systems because the system settings are complex. In this paper, a function was proposed and implemented to monitor only the file access in Microsoft Windows environment. Test result shows that this function could protect files from unallowed access and then minimize the overhead of application execution time.
[aiguo-02:2009]	Kazuya Matsumura, Shirai Daisukey, and Aiguo HE. A C Language Programming Education Support System based on Software Visualization. In Proceedings of the 2009 Joint Conferences on Pervasive Computing, 2009.
	C language is a major computer programming language, being widely used in software system development and education of computer science. However, comparing with other computer languages, C language is difficult and little uninteresting to its beginners and therefore, it takes more time to learn or teach. To give those beginners a interesting and comprehensible way to learn C language, we proposed a technique to make C language program visible. By this technique, the change of program status such as variable value in each step can be displayed in a graphical way. The effectiveness of this proposal was confirmed by experiments.
[z-cheng-06:2009]	H. Ozaki, A. Kara, and Z. Cheng. User-Perceived Reliability of Shared Protection Systems with a Finite Number of Repairers. In IEEE International Conference on Computer and Information Technology (CIT), pages 3–8, Xiamen China, Oct. 2009.
	In this paper we investigate the user-perceived availability and Mean Time to Failure (MTTF) of M-for-N shared protection systems with a finite number of repairers.
[z-cheng-07:2009]	Junbo Wang, Zixue Cheng, Kaoru Ota, Lei Jing, and Mizuo Kansen. A Composition Method for Manipulating Detectable Situations to Provide Situation-aware Services. In The 2nd IEEE International Conference on Ubi-media Computing (U-Media 2009), Tamkang University, Taipei, Taiwan., December 2009,. Tamkang University.
	One of the hot topics in ubiquitous computing is context-aware services, which automatically adapt user based on user ’s context information, e.g., location, time, favorite etc. Situation-aware services are advanced context-aware services, such that more complex context information and relations among users, objects, and environment are taken into consideration. In order to provide the situationaware services, it is necessary to describe the situations, to define and link services which will be provided in the situations, and to detect the happening of the situations in the real world. Though many researches have worked on context-aware services, there are not so many on situation aware services, especially on describing and detecting the situations uniformly. In this paper, we take a composition approach to solve the problems. We first define primitive situations which are based on J. Barwise ’s situation theory and can be detected by current ubiquitous techniques. And then, we present several manipulation rules, by which more complex situations can be composed. Our methods can be used as a building block in construction situation-aware services, such as warning to a user to prevent him/her from dangerous situations, reminding a user not forgetting to bring belongings with him/her, navigation to a handicapped user, etc.
[z-cheng-08:2009]	Zixue Cheng, Mizuo Kansen, and Tongjun Huang. Troublesome Detectable Context-aware Services based on Game-theory. In The 2nd IEEE International Conference on Ubi-media Computing (U-Media 2009), Taipei, Taiwan., December 2009. Tamkang University.
	With rapid progress on ubiquitous technologies, various services become available at anytime and anywhere. One of hot topics in ubiquitous computing is contextaware services, which provide the services at proper time and proper place, in a proper way personalized to a user. However, there may be conflicts of services among users whose contexts are overlapped. Moreover, a context-aware service convenient for a user may cause another user ’s unpleasantness even troublesome. In this paper, we consider the relations between contexts of different users. A mechanism consisting of multi-agents, to find and reduce the unpleasantness of users due to context-aware services is constructed based on game-theory.
[z-cheng-09:2009]	Hui-Huang Hsu, Zixue Cheng, Timothy K. Shih, and Chien-Chen Chen. RFID-Based Personalized Behavior Modeling. In The International Workshop on Pervasive Media (PerMedia 2009) in Symposia and Workshops on Ubiquitous, Autonomic and Trusted Computing, pages 350–355, Brisbane, Australia,, July 2009.
	In this research, we aim at building an intelligent system that can detect abnormal behavior for the elderly at home. Deployment of RFID tags at home helps us collect the daily movement data of the elderly. The clustering technique is then used to build a personalized model of normal behavior based on these RFID data. After the model is built, any incoming datum outside the model can be seen as abnormal. In this paper, we present the design of the system architecture and show the preliminary results for data collection and preprocessing.
[z-cheng-10:2009]	Kaoru Ota, Hikaru Nihei, Junbo Wang, Lei Jing, Mizuo Kansen, and Zixue Cheng. A Courseware Platform for Safety Education through Dual Experience based Learning Using an Integrated Environment of a Miniaturized World and a Computerized World. In The 2nd IEEE International Conference on Ubi-media Computing (U-Media 2009), Tamkang University, Taipei, Taiwan., December 2009,. Tamkang University.
	Ubiquitous computing has been widespread. Ubiquitous learning is one of fields utilizing such technologies and gives learners more effective and personalized education than the traditional one. Safety education is necessary for children since accidents and crimes against them happen increasingly in recent years. The children might need to protect them from dangers by themselves. It is important for the children to learn safety knowledge through real experiences on dangers. However, it is not always realizable because of lack of opportunities and possibilities of hurting the children. In contrast, a virtual experience is possible and popular to educate the children in some way such as using computers. However, only virtual experiences might be insufficient for children to practice what they learnt in the real world. Therefore we propose a novel approach by fusing a real world and virtual space to let a learner have dual experiences in both real and virtual worlds. We design a support system which employs the following techniques: (1) a platform of dual experiencing learning, (2) dual experiencing learning scenario design policies, and (3) personalized dual experiencing learning course.
[z-cheng-11:2009]	Junbo Wang, Kaoru Ota, Lei Jing, Mizuo Kansen, and Zixue Cheng. A Smart Gate for Composing Multi-individuals to Provide Contextaware Services. In The 1st International Workshop on Aware Computing (IWAC2009), pages pp. 658–664, Aizu-Wakamatsu, Japan, September 2009. Japan Society for Fuzzy Theory and Intelligent Informatics.
	Context-aware computing systems can sense user ’s physical environment, and adapt their behavior automatically. Thus it is very important to define, represent, detect, and manage the contexts. The rapid progress of smart object augmented by ability of sensing, computing, wireless communication makes the development of context-aware more convenient. And then composition of smart objects becomes a key technology when providing services, which means related smart objects and users are automatically composed together, to provide appropriate services with deep consideration of status, activities, and properties of the users and smart objects. Therefore, in this paper, we propose a smart gate which can (1) set up a bridge among multiple individuals including a user and smart objects, (2) enhance the coordination of services and individuals, and (3) solve problem of conflicting services.

Ph.D, Master and Graduation Theses

[z-cheng-12:2009]	Qin Zhang. Master Thesis: A New Hazard Analysis Method for Safety-Critical Systems based on System-Environment Interactions, University Thesis Advisor: Zixue Cheng
[z-cheng-13:2009]	Takuya Itagaki. Graduation Thesis: A Support System for Improving the Lifestyles of Children by Using Ubiquitous Pets, University of Aizu, Mar 2010. Thesis Advisor: Zixue Cheng
[z-cheng-14:2009]	Taishi Yoshida. Graduation Thesis: A Reminding System to Prevent Losses by Comparing Movements between a User and His/Her Belongings by Using Acceleration Sensors, University of Aizu, Mar 2010. Thesis Advisor: Zixue Cheng
[z-cheng-15:2009]	Tatsuya Hasegawa, Graduation Thesis: A Navigation Support System for Two Vehicles to Travel the Same Route, University of Aizu, Mar 2010. Thesis Advisor: Zixue Cheng
[z-cheng-16:2009]	Masayuki Nemoto. Graduation Thesis: Evaluation of a Courseware System for Children ’s Safety Education based on Simulated Experience, University of Aizu, Mar 2010. Thesis Advisor: Zixue Cheng
[z-cheng-17:2009]	Shota Hirasawa. Graduation Thesis: An Algorithm for Efficient Data Collection using Mobile Agents in a Sensor Network, University of Aizu, Mar 2010. Thesis Advisor: Zixue Cheng
[z-cheng-18:2009]	Hirokazu Ozaki. Doctor Thesis: User-Perceived Reliability of Fault- Tolerant Systems with Shared Backup Units, University of Aizu, Sep 2009. Thesis Advisor: Zixue Cheng with the Univeristy of Aizu and Prof. Atsushi Kara with Narakosen
[z-cheng-19:2009]	Mizuo Kansen. Doctor Thesis:Analysis Methods for Grasping Learner’s Status from Multiple Viewpoints and Their Applications to e- Learning Systems, University of Aizu, Mar 2010. Thesis Advisor: Zixue Cheng

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