Effective Location Based Services with Dynamic Data Management in Mobile Environments

With the proliferation of mobile computing technologies, location based services have been identified as one of the most promising target application. We classify mobile information service domains based on feature characteristics of the information sources and different patterns of mobile information access. By carefully examining the service requirements, we identify the dynamic data management problem that must be addressed for effective location based services in mobile environments. We then devise a general architecture and cost model for servicing both location independent and location dependent data. Based on the architecture and cost model, we propose a set of dynamic data management strategies that employs judicious caching, proactive server pushing and neighborhood replication to reduce service cost and improve response time under changing user mobility and access patterns. Detail behavior analysis helps us in precisely capturing when and how to apply these strategies. Simulation results suggest that different strategies are effective for different types of data in response to different patterns of movement and information access. Shiow-yang Wu is an associate professor of the Department of Computer Science and Information Engineering at National Dong Hwa University, Hualien, Taiwan, R.O.C. He received the BS and MS degrees in computer engineering from National Chiao Tung University, Hsinchu, Taiwan, ROC, and the PhD degree in computer science from the University of Texas at Austin in 1984, 1986, and 1995, respectively. His research interests include data/knowledge bases, mobile computing, distributed processing, intelligence information systems, and electronic commerce. Kun-Ta Wu was born in Taipei, Taiwan, R.O.C., in 1976. He received the B.S. degree in computer science from Soochow University, Taipei, Taiwan, R.O.C., in 1999 and the M.S. degree in computer science and information engineering from National Dong Hwa University, Hualien, Taiwan, R.O.C., in 2001. Currently, he is an Assistant Researcher in the Domestic Division at Science and Technology Information Center, National Science Council, R.O.C., as a member of Information Gathering and Analysis Group of National Information and Communication Security Taskforce. His research interests include mobile computing, wireless network and information security.     

Repacking on Demand for Hierarchical Cellular Networks

In mobile telecommunications operation, radio channels are scarce resources and should be carefully assigned. One possibility is to deploy the hierarchical cellular network (HCN). This paper studies a HCN channel assignment scheme called repacking on demand (RoD). RoD was originally proposed for wireless local loop networks. We expend this work to accommodate mobile HCN. A simulation model is proposed to study the performance of HCN with RoD and some previously proposed schemes. Our study quantitatively indicates that RoD may significantly outperform the previous proposed schemes. Hsien-Ming Tsai was born in Tainan, Taiwan, R.O.C., in 1973. He received the double B.S. degrees in Computer Science & Information Engineering (CSIE) and Communication Engineering, the M.S. degree in CSIE, and the Ph.D. degree in CSIE from National Chiao-Tung University (NCTU), Taiwan, in 1996, 1997, and 2002, respectively. He is currently a research specialist in Quanta Research Institute, Quanta Computer Inc. His research interests are in the areas of cellular protocols (UMTS/GPRS/GSM/DECT), cellular multimedia (MPEG-4 Audio/Speech), and embedded systems. He is an IEEE member. Ai-Chun Pang was born in Hsinchu, Taiwan, R.O.C., in 1973. She received the B.S., M.S. and Ph.D. degrees in Computer Science and Information Engineering from National Chiao Tung University (NCTU) in 1996, 1998 and 2002, respectively. She joined the Department of Computer Science and Information Engineering, National Taiwan University (NTU), Taipei, Taiwan, as an Assistant Professor in 2002. Her research interests include design and analysis of personal communications services network, mobile computing, voice over IP and performance modeling. Yung-Chun Lin was born in Kaohsiung, Taiwan, R.O.C., in 1978. He received the B.S. and M.S. degrees in Computer Science and Information Engineering (CSIE) from National Chiao-Tung University (NCTU), Taiwan, in 2001, 2003, respectively. He is currently pursuing the Ph.D. degree in CSIE. His research interests include design and analysis of a personal communications services network, the cellular protocols (UMTS/GPRS/GSM), and mobile computing. Yi-Bing Lin received his BSEE degree from National Cheng Kung University in 1983, and his Ph.D. degree in Computer Science from the University of Washington in 1990. From 1990 to 1995, he was with the Applied Research Area at Bell Communications Research (Bellcore), Morristown, NJ. In 1995, he was appointed as a professor of Department of Computer Science and Information Engineering (CSIE), National Chiao Tung University (NCTU). In 1996, he was appointed as Deputy Director of Microelectronics and Information Systems Research Center, NCTU. During 1997-1999, he was elected as Chairman of CSIE, NCTU. His current research interests include design and analysis of personal communications services network, mobile computing, distributed simulation, and performance modeling. Dr. Lin has published over 150 journal articles and more than 200 conference papers. Lin is an Adjunct Research Fellow of Academia Sinica, and is Chair Professor of Providence University. Lin serves as consultant of many telecommunications companies including FarEasTone and Chung Hwa Telecom. Lin is an IEEE Fellow and an ACM Fellow.     

High Performance Wireless Switch Protocol for IEEE 802.11 Wireless Networks

All mobile stations (STAs) in IEEE 802.11 infrastructure wireless local area networks (IWLAN) are coordinated by an access point (AP). Within the 2.4 GHz unlicensed industry, science, and medicine (ISM) band defined in the IEEE 802.11 2.4 GHz physical layer (PHY) specifications, three channels are available for concurrently transferring data packets at the coverage area of an AP. In most of small/medium enterprises or home environments, an AP with one selected channel is sufficient for covering whole service area, but this implies that the radio resources for the remaining two channels are wasted. In order to overcome the drawback, we propose a new and simple media access control (MAC) protocol, named wireless switch protocol (WSP), for increasing the throughput of IEEE 802.11 IWLAN network to support high quality multimedia traffic. This is achieved by allowing any pair of STAs in IWLAN to exchange data packets in one of other idle channels after their handshake with each other in the common channel controlled by AP. Simulation results show that the total network throughput of WSP depends on the time taken by channel switching, and on the ‘Intranet’ and ‘Internet’ traffic distribution, where the Intranet and Internet mean data transmission between STAs in IWLAN and between the STA and wired host, respectively. When all data packets are Intranet traffic and the traffic load is heavy, the ratio of Goodput for the proposed WSP to that of IEEE 802.11 standard approximates 400%. In the worse case of all Internet traffic, the proposed WSP still obtains the similar throughput as that of IEEE 802.11 standard.Jenhui Chen was born on October 12, 1971 in Taipei, Taiwan, Republic of China. He received the Bachelor’s and Ph.D. degree in Computer Science and Information Engineering (CSIE) from Tamkang University in 1998 and 2003, respectively. In the Spring of 2003, he joined the faculty of Computer Science and Information Engineering Department at Chang Gung University and served as the Assistant Professor. He occupies the supervisor of Network Department in the Information Center, Chang Gung University. Dr. Chen once served the reviewer of IEEE Transactions on Wireless Communications, ACM/Kluwer Mobile Networks and Applications (MONET), and Journal of Information Science and Engineering. His main research interests include design, analysis, and implementation of communication and network protocols, wireless networks, milibots, and artificial intelligence. He is a member of ACM and IEEE.Ai-Chun Pang was born in Hsinchu, Taiwan, R.O.C., in 1973. She received the B.S., M.S. and Ph.D. degrees in Computer Science and Information Engineering from National Chiao Tung University (NCTU) in 1996, 1998 and 2002, respectively. She joined the Department of Computer Science and Information Engineering, National Taiwan University (NTU), Taipei, Taiwan, as an Assistant Professor in 2002. Her research interests include design and analysis of personal communications services network, mobile computing, voice over IP, and performance modeling.Shiann-Tsong Sheu received his B.S. degree in Applied Mathematics from National Chung Hsing University in 1990, and obtained his Ph.D. degree in Computer Science from National Tsing Hua University in May of 1995. From 1995 to 2002, he was an Associate Professor at the Department of Electrical Engineering, Tamkang University. Since Feb. 2002, he has become a Professor at the Department of Electrical Engineering, Tamkang University. Dr. Sheu received the outstanding young researcher award by the IEEE Communication Society Asia Pacific Board in 2002. His research interests include next-generation wireless communication, WDM networks and intelligent control algorithms.Hsueh-Wen Tseng received his B.S. degree in electrical engineering from Tamkang University, Taipei country, Taiwan, in 2001 and M.S. degree in electrical engineering from National Taiwan University of Science and Technology, Taipei, Taiwan, in 2003. He is currently pursuing the Ph. D. degree at the Department of Computer Science and Information Engineering, National Taiwan University, Taipei, Taiwan. His research interests include design, analysis and implementation of network protocols and wireless communications.     

Private Authentication Techniques for the Global Mobility Network

Numerous authentication approaches have been proposed recently for the global mobility network (GLOMONET), which provides mobile users with global roaming services. In these authentication schemes, the home network operators can easily obtain the authentication key and wiretap the confidentiality between the roaming user and the visited network. This investigation provides a solution of authentication techniques for GLOMONET in order to prevent this weakness from happening and presents a secure authentication protocol for roaming services. In addition, a round-efficient version of the same authentication protocol is presented. Comparing with other related approaches, the proposed authentication protocol involves fewer messages and rounds in communication. Tian-Fu Lee was born in Tainan, Taiwan, ROC, in 1969. He received his B.S. degree in Applied Mathematics from National Chung Hsing University, Taiwan, in 1992, and his M.S. degree in Computer Science and Information Engineering from National Chung Cheng University, Taiwan, in 1998. He works as a lecturer in Leader University and pursues his Ph.D. degree at Department of Computer Science and Information Engineering, National Cheng Kung University, Taiwan. His research interests include cryptography and network security. Chi-Chao Chang received the BS degree in Microbiology from Soochow University in 1990 and the MS degree in Computer Science from State University of New York at Albany in 1992. He is currently working as an instructor in Chang Jung Christian University and a graduate student in National Cheng Kung University. His research interests are information security, mobile agent systems, anonymous digital signatures and quantum cryptography. Tzonelih Hwang was born in Tainan, Taiwan, in March 1958. He received his undergraduate degree from National Cheng Kung University, Tainan, Taiwan, in 1980, and the M.S. and Ph.D. degrees in Computer Science from the University of Southwestern Louisiana, USA, in 1988. He is presently a professor in Department of Computer Science and Information Engineering, National Cheng Kung University. His research interests include cryptology, network security, and coding theory.     

Scheduling for time-division based shared channel allocation for UMTS

The Universal Mobile Telecommunications System (UMTS) adopts the WCDMA technology as the radio access interface to provide variable transmission rate services. There are four classes of connections identified in UMTS, which are the conversational, streaming, interactive, and background connections. To efficiently utilize radio bandwidth, the shared channel approach is proposed to deliver the packets for the interactive and background connections. This paper proposes a “Shared-Channel Assignment and Scheduling” (SCAS) algorithm to periodically allocate shared channels to serve interactive and background connections. We conduct formal mathematical proofs and simulation experiments to investigate the performance of the SCAS algorithm. We formally prove that with SCAS, a shared channel can be fully utilized (i.e., the utilization of a shared channel can be up to 100%) to serve the interactive connections. Our analysis indicates that compared with the previously proposed shared channel allocation and scheduling algorithms, there are less computation and communication overheads introduced in the SCAS algorithm. The results of the simulation experiments indicate that it is preferred to set up the Transmission Time Interval (TTI; that is, the unit of time interval for shared channel allocation) smaller to optimize the performance of the SCAS algorithm, including the shared channel utilization and the average waiting time of a connection before getting transmission service. A preliminary version [11] of this work has been accepted by IEEE Wireless Communications and Networking Conference 2004. This paper is an extension of the proposed algorithm, and simulation and analysis are conducted to investigate the performance of the proposed algorithm. Chai-Hien Gan was born in Malaysia in 1971. He received his BS degree in computer science from Tamkang University in 1994, Taipei County, Taiwan, and both his MS. and Ph.D. degrees in computer science and information engineering from National Taiwan University, Taipei, Taiwan, in 1996 and 2005, respectively. Since March 2005, he has been a Research Assistant Professor in Department of Computer Science, National Chiao Tung University, R.O.C. His current research interests include wireless mesh networks, mobile computing, personal communications services, and wireless Internet. Phone Lin received his BSCSIE degree and Ph.D. degree from National Chiao Tung University, Taiwan, R.O.C. in 1996 and 2001, respectively. From August 2001 to July 2004, he was an Assistant Professor in Department of CSIE and Graduate Institute of Graduate of Networking and Multimedia, National Taiwan University, R.O.C. Since August 2004, he has been an Associate Professor in Department of CSIE and Graduate Institute Graduate of Networking and Multimedia, National Taiwan University, R.O.C. His current research interests include personal communications services, wireless Internet, and performance modeling. Dr. Lin is an Associate Editor for IEEE Transactions on Vehicular Technology, Editor for IEEE Wireless Communications special issue on Mobility and Resource Management and a Guest Editor for ACM/Springer MONET special issue on Wireless Broad Access. He is also an Associate Editorial Member for the WCMC Journal. P. Lin’s email and website addresses are plin@csie.ntu.edu.tw and http://www.csie.ntu.edu.tw/~plin, respectively. Nei-Chiung Perng is presently a Ph.D. student in the Department of Computer Science and Information Engineering, National Taiwan University. He received his Bachelor and Master degrees in the Department of Computer and Information Science, National Chiao Tung University in 1999 and 2001, respectively. His research interests include real-time systems and scheduling algorithms. Tei-Wei Kuo received B.S.E. degree in computer science and information engineering from National Taiwan University in Taipei, Taiwan, in 1986. He received the M.S. and Ph.D. degrees in computer sciences from the University of Texas at Austin in 1990 and 1994, respectively. He is currently a Professor and the Chairman of the Department of Computer Science and Information Engineering of the National Taiwan University, Taiwan, ROC. He was an Associate Professor in the Department of Computer Science and Information Engineering of the National Chung Cheng University, Taiwan, ROC, from August 1994 to July 2000. Dr. Kuo is a senior member of the IEEE computer society. His research interest includes embedded systems, real-time process scheduling, real-time operating systems, and real-time databases. He has over 100 technical papers published or been accepted in international journals and conferences and has a book “Real-Time Database Systems: Architecture and Techniques” published by Kluwer Academic Publishers (ISBN 0-7923-7218-2, USA). He is the Program Co-Chair of IEEE 7th Real-Time Technology and Applications Symposium, 2001, and an associate editor of the Journal of Real-Time Systems since 1998. He is an executive committee member of the IEEE Technical Committee on Real-Time Systems in 2005 and the steering committee chair of IEEE RTCSA’05. Dr. Kuo has consulted for government and industry on problems in various real-time and embedded systems designs. Dr. Kuo received several research awards in Taiwan, including the Distinguished Research Award from the ROC National Science Council in 2003 and the Young Scholar Research Award from Academia Sinica, Taiwan, ROC, in 2001. Ching-Chi Hsu was born in Taipei, Taiwan in 1949. He received his BS degree in physics from National Tsing Hwa. University in 1971, Hsishu, Taiwan, and both his MS. and Ph.D. degrees in computer engineering from EE department of National Taiwan University, Taipei, Taiwan, in 1975 and 1982, respectively. In 1977, he joined the faculty of the Department of Computer Science and Information Engineering at National Taiwan University and became an associate professor in 1982. During the years between 1987 and 2002, he was first engaged as a professor and became the chairman of the department. During his tenure in National Taiwan University, Dr. Hsu was a visiting scholar of Computer Science Department, Stanford University from 1984 to 1985. After serving in National Taiwan University for over 25 years, Dr. Hsu had left and was promoted as the president of Kai Nan University in 2002. Starting from February 2004, Dr. Hsu has been the executive vice president of the Institute for Information Industry in which he is mainly in charge of accelerating the growth of information industry in the whole nation. His research interests include distributed processing of data and knowledge, mobile computing and wireless networks.     

A Credit-Based On-Demand QoS Routing Protocol Over Bluetooth WPANs

The quality-of-service (QoS) communication that supports mobile applications to guarantee bandwidth utilization is an important issue for Bluetooth wireless personal area networks (WPANs). In this paper, we address the problem of on-demand QoS routing with interpiconet scheduling in Bluetooth WPANs. A credit-based QoS (CQ) routing protocol is developed which considers different Bluetooth packet types, because different types of Bluetooth packets have different bandwidth utilization levels. This work improves the bandwidth utilization of Bluetooth scatternets by providing a new interpiconet scheduling scheme. This paper mainly proposes a centralized algorithm to improve the bandwidth utilization for the on-demand QoS routing protocol. The centralized algorithm incurs the scalability problem. To alleviate the scalability problem, a distributed algorithm is also investigated in this work. The performance analysis illustrates that our credit-based QoS routing protocol achieves enhanced performance compared to existing QoS routing protocols.This work was supported by the National Science Council of the Republic of China under grant nos. NSC-92-2213-E-194-022 and NSC-93-2213-E-194-028. Yuh-Shyan Chen received the B.S. degree in computer science from Tamkang University, Taiwan, Republic of China, in June 1988 and the M.S. and Ph.D. degrees in Computer Science and Information Engineering from the National Central University, Taiwan, Republic of China, in June 1991 and January 1996, respectively. He joined the faculty of Department of Computer Science and Information Engineering at Chung-Hua University, Taiwan, Republic of China, as an associate professor in February 1996. He joined the Department of Statistic, National Taipei University in August 2000, and joined the Department of Computer Science and Information Engineering, National Chung Cheng University in August 2002. Dr. Chen served as Co-Editors-in-Chief of International Journal of Ad Hoc and Ubiquitous Computing (IJAHUC), Editorial Board Member of Telecommunication System Journal, International Journal of Internet Protocol Technology (IJIPT) and The Journal of Information, Technology and Society (JITAS). He also served as Guest Editor of Telecommunication Systems, special issue on “Wireless Sensor Networks” (2004), and Guest Editor of Journal of Internet Technology, special issue on “Wireless Internet Applications and Systems” (2002) and special issue on “Wireless Ad Hoc Network and Sensor Networks” (2004). He was a Vice Co-Chair, Wireless IP Symposium of WirelressCOM2005, USA (2005) and a Workshop Co-Chair of the 2001 Mobile Computing Workshop, Taiwan. Dr. Chen also served as IASTED Technical Committee on Telecommunications for 2002–2005, WSEAS International Scientific Committee Member (from 2004), Program Committee Member of IEEE ICPP'2003, IEEE ICDCS'2004, IEEE ICPADS'2001, ICCCN'2001–2005, MSN'2005, IASTED CCN'2002–2005, IASTED CSA'2004–2005, IASTED NCS'2005, and MSEAT'2003–2005. His paper wins the 2001 IEEE 15th ICOIN-15 Best Paper Award. Dr. Chen was a recipient of the 2005 Young Scholar Research Award given by National Chung Cheng University to four young faculty members, 2005. His recent research topics include mobile ad-hoc network, wireless sensor network, mobile learning system, and 4G system. Dr. Chen is a member of the IEEE Computer Society, IEICE Society, and Phi Tau Phi Society. Keng-Shau Liu received the M.S. degree in Computer Science and Information Engineering from National Chung Cheng University, Taiwan, Republic of China, in July 2004. His research includes wireless LAN, Bluetooth, and mobile learning.     

A Mobile Ticket System Based on Personal Trusted Device

Advances in wireless network technology and the continuously increasing users of Personal Trusted Device (PTD) make the latter an ideal channel for offering personalized services to mobile users. In this paper, we apply some cryptology (such as public key infrastructure, hashing chain and digital signature) to propose a realistic mobile ticket system such that fairness, non-repudiation, anonymity, no forging, efficient verification, simplicity, practicability and obviate the embezzlement issues can be guaranteed. On the basis of PTD is more portable and personal than personal computer, we gradually perceived that the widely used PTD will present huge commerce profits for mobile ticket service provider and it is convenient to the PTD user. Yu-Yi Chen was born in Kaohsiung, Taiwan, in 1969. He received the B.S., M.S., and Ph.D. in Applied Mathematics from the National Chung Hsing University in 1991, 1993, and 1998, respectively. He is presently an assistant professor of the Department of International Business at Providence University, Taiwan. His research interests include computer cryptography, network security, and e-commerce. Chin-Ling Chen was born in Taiwan in 1961. He received the B.S. degree in Computer Science and Engineering from the Feng Cha University in 1991; the M.S. degree and Ph.D. in Applied Mathematics at National Chung Hsing University, Taichung, Taiwan, in 1999 and 2005 respectively. He is currently an assistant professor of the Department of Computer Science and Information Engineering at Chaoyang University of Technology, Taiwan. He is a member of the Chinese Association for Information Security. From 1979 to 2005, he was a senior engineer at the Chunghwa Telecom Co., Ltd. His research interests include cryptography, network security and electronic commerce. Jinn-Ke Jan was born in Taiwan in 1951. He received the B.S. degree in physics from the Catholic Fu Jen University in 1974 and the M.S. degree in information and computer science from University of Tokyo in 1980. He studied Software Engineering and Human-Computer Interface in the University of Maryland, College Park, MD, during 1984–1986. He is presently a professor in the institute of Computer Science at National Chung Hsing University. He is currently also an editor of Information and Education, an editor of Journal of Computers, and an executive member of the Chinese Association for Information Security. He is a member of IACR and member of IEEE. From 1995 to 1997, he was the Director of the Counseling Office for Overseas Chinese and Foreign Students. From 1997 to 2000, he was the Director of the Computer Center at National Chung Hsing University. His research interests include computer cryptography, human factors of designing software and information systems, ideograms I/O processing, data structures and coding theory.     

A Development Environment for OSA-Based Applications over the Interworked WLAN and Cellular Networks

In this paper, we propose an OSA-based development environment for interworking WLAN and 3G cellular networks. The main goal of our work is to establish and create an environment that can serve as a demonstration of a working network for OSA-based application developers while featuring mobile services over the interworked LAN and 3G cellular networks. The proposed simulating environment has (i) a location update scheme that is used to obtain mobile users' locations and status information over the interworked WLAN and cellular networks, (ii) an instant message gateway (IMG) simulator that is developed to send and receive generic messages over the interworked WLAN and cellular networks, and (iii) a mapping of Parlay APIs onto SIP signaling messages for multiparty call applications over the interworked WLAN and cellular networks. An illustrated OSA-based application that utilizes the corresponding system functions and modules is developed and verified using the proposed simulating environment. Chung-Ming Huang received the B.S. degree in Electrical Engineering from National Taiwan University on 1984/6, and the M.S. and Ph.D. degrees in Computer and Information Science from The Ohio State University on 1987/12 and 1991/6 respectively. He is currently a professor in Department of Computer Science and Information Engineering, National Cheng Kung University, Taiwan, R.O.C. He is the director of The Promotion Center for Network Applications and Services, Innovative Communication Education Project, Ministry of Education, Taiwan, R.O.C. His research interests include broadband Internet and applications, wireless and mobile network protocols, ubiquitous computing and communications, and multimedia streaming. Tz-Heng Hsu received the B.S. degree from Department of Computer Science and Information Engineering, Feng Chia University on 1996/6, and the M.S. degree and Ph.D from Department of Computer Science and Information Engineering, National Cheng Kung University on 1998/7 and 2005/7, Taiwan, R.O.C. He is currently a assistant professor in Department of Computer Science and Information Engineering, Southern Taiwan University of Technology. His research interests are wireless and mobile network protocols, applications over interworked WLAN and cellular networks and communications, and multimedia streaming. Chih-Wen Chao received the B.S. degree from Department of Engineering Science, National Cheng Kung University on 2003/6, and the M.S. degree from Department of Computer Science and Information Engineering, National Cheng Kung University on 2005/7, Taiwan, R.O.C. His research interests are OSA-based applications and distributed multimedia systems.     

A novel encoding scheme and data delivery in ubiquitous computing systems

Accessing information through wireless devices is becoming more and more popular. When the size of the accessed information is large, a great amount of access latency is incurred while a mobile user (MU) migrates across cells. This paper investigates this problem and proposes an effective way of delivering such data to the MU in ubiquitous computing systems. A cell-encoding scheme is proposed for the support of this efficient data delivery. The method is carefully evaluated on its feasibility and efficiency. Chao-Chun Chen received his Ph.D. degree in the Department of Computer Science and Information Engineering at the National Cheng-Kung University, Taiwan, in 2004. Currently, he is an assistant professor of the Department of Information Management, Shih-Chien University Kaohsung Campus, Taiwan. His research interests include mobile/wireless data management, sensor networks, spatio-temporal databases, and web information retrieval. Chiang Lee received the B.S. degree from the National Cheng-Kung University, Taiwan, in 1980 and the M.E. and Ph.D. degrees in electrical engineering from the University of Florida, Gainesville, Florida, in 1986 and 1989, respectively. He joined IBM Mid-Hudson Laboratories, Kingston, NY in 1989 and participated in a project working on the design and performance analysis of a parallel and distributed database system. He joined the faculty of National Cheng-Kung University in 1990 and is currently a professor of the Department of Computer Science and Information Engineering of the university. His research interests are in the areas of mobile computing, sensor networks, and database systems. He has many papers published in major database journals and conferences, and has been invited as an author of a chapter for several technical books. Dr. Lee also served as a Steering Committee member of the DASFAA International Conference from 1996 to 1998, and served on organizing and program committee for several major international conferences. Lien-Fa Lin received his M.E. degree in the Department of Computer Science and Engineering at the Yuan Ze University, Taiwan, in 1993. Currently, he is a Ph.D. student of the Department of Computer Science and Information Engineering at the National Cheng-Kung University, Taiwan. His research interests include mobile/wireless data management, spatio-temporal databases, and web information retrieval.     

Implementation and performance evaluation for a ubiquitous and unified multimedia messaging platform

As networking technology advances, more advanced message services are provided. Users may have one or more different message accounts and devices. Before sending messages, the sender must make sure which message service the receipt currently uses. Any misjudgement may delay the time when the messages are received. To make users be able to receive messages anytime and anywhere with any kind of devices, we propose a Ubiquitous and Unified Multimedia Messaging (UMM) platform. The UMM platform integrates different message services and provides a more efficient way for message delivery. Our design does not modify the existing protocols of message services and need not involve the network operators. An analytical model is proposed to evaluate the performance of the implemented platform. Our study shows that with a large number of message services the user subscribes and long message processing time in the network, the delayed message probability can be limited within 1.5%. This performance is considered satisfactory. This paper is an extension of the work that has won the second place of the Mobile Hero contest sponsored by Industrial Development Bureau of Ministry of Economic Affairs, Taiwan, R.O.C., and was awarded USD 15,000. Phone Lin (M’02-SM’06) received his BSCSIE degree and Ph.D. degree from National Chiao Tung University, Taiwan, R.O.C. in 1996 and 2001, respectively. From August 2001 to July 2004, he was an Assistant Professor in Department of Computer Science and Information Engineering (CSIE), National Taiwan University, R.O.C. Since August 2004, he has been an Associate Professor in Department of CSIE and in Graduate Institute of Networking and Multimedia, National Taiwan University, R.O.C. His current research interests include personal communications services, wireless Internet, and performance modeling. Dr. Lin is an Associate Editor for IEEE Transactions on Vehicular Technology, a Guest Editor for IEEE Wireless Communications special issue on Mobility and Resource Management, and a Guest Editor for ACM/Springer MONET special issue on Wireless Broad Access. He is also an Associate Editorial Member for the WCMC Journal. Dr. Lin has received many research awards. He was a recipient of Research Award for Young Researchers from Pan Wen-Yuan Foundation in Taiwan in 2004, a recipient of K. T. Li Young Researcher Award honored by ACM Taipei Chapter in 2004, a recipient of Wu Ta You Memorial Award of National Science Council (NSC) in Taiwan in 2005, a recipient of Fu Suu-Nien Award of NTU in 2005 for his research achievements. Dr. Lin is listed in WHO’S WHO IN SCIENCE AND ENGINEERING(R) in 2006. Dr. Lin is a Senior Member, IEEE. P. Lin’s email and website addresses are plin@csie.ntu.edu.tw and respectively. Shan-Hung Wu received the B.S. degree from Department of Information Management, National Central University, Jhongli, Taiwan, and M.S. degree from Department of Computer Science and Information, National Taiwan University, Taipei, Taiwan. He is currently a Ph.D. candidate at Department of Electrical Engineering, National Taiwan University, Taipei, Taiwan. His research interests include distributed data management, pervasive computing, wireless and sensor networks, and performance modeling. Chung-Min Chen is Director of Telcordia Applied Research Center in Taiwan. His research interests span across areas in distributed computing, data engineering, telecommunication and network management. He received a Ph.D. in Computer Science from the University of Maryland, College Park and a B.S. in Computer Science and Information Engineering from National Taiwan University. Ching-Feng Liang received M.S. degree in electronic engineering from National Taiwan University of Science & Technology (NTUST) in 1993 and joined the Information & Communication Laboratory (ICL) of Industrial Technology Research Institute (ITRI) as an engineer. Liang has led more than 10 projects of Taiwan Ministry of Economic Affairs (MoEA) to study and develop the technologies of mobile network and services including GPRS/3G core network, WLAN/Cellular interworking and number portability service. Liang received the ITRI Award in 2005 and the Outstanding Project Award of Taiwan MoEA in 2003. Liang is currently the manager of the Core Network Department of ICL/ITRI.     

An On-Demand Routing Protocol with Backtracking for Mobile Ad Hoc Networks

A mobile ad hoc network (MANET) is characterized by multi-hop wireless links and frequent node mobility. Communication between non-neighboring nodes requires a multi-hop routing protocol to establish a route. But, the route often breaks due to mobility. The source must rediscover a new route for delivering the data packets. This wastes the resources that are limited in MANET. In this paper, a new on-demand routing protocol is proposed, named on-demand routing protocol with backtracking (ORB), for multi-hop mobile ad hoc networks. We use the multiple routes and cache data technique to reduce the rediscovery times and overhead. After executing the route discovery phase, we find out a set of nodes, named checkpoint, which has the multiple routes to the destination. When a checkpoint node receives a data packet, it caches this data packet in its buffer within a specific time period. When a node detects a broken route during the data packets delivery or receives an error packet, it will either recover the broken route or reply the error packet to the source. If a node can not forward the data packet to the next node, it replies an error packet to the source. This packet is backtracking to search a checkpoint to redeliver the data packet to the destination along other alternate routes. The main advantage of ORB is to reduce the flooding search times, maybe just delay and cost while a route has broken. The experimental results show that the proposed scheme can increase the performance of delivery but reduce the overhead efficiently comparing with that of AODV based routing protocols. Hua-Wen Tsai received the B.S. degree in Information Management from Chang Jung Christian University, Taiwan, in June 1998 and the M.B.A. degree in Business and Operations Management from Chang Jung Christian University, Taiwan, in June 2001. Since September 2001, he has been working towards the Ph.D. degree and currently is a doctoral candidate in the Department of Computer Science and Information Engineering, National Cheng Kung University, Taiwan. His research interests include wireless communication, ad hoc networks, and sensor networks. Tzung-Shi Chen received the B.S. degree in Computer Science and Information Engineering from Tamkang University, Taiwan, in June 1989 and the Ph.D. degree in Computer Science and Information Engineering from National Central University, Taiwan, in June 1994. He joined the faculty of the Department of Information Management, Chung Jung University, Tainan, Taiwan, as an Associate Professor in June 1996. Since November 2002, he has become a Full Professor at the Department of Information Management, Chung Jung University, Tainan, Taiwan. He was a visiting scholar at the Department of Computer Science, University of Illinois at Urbana-Champaign, USA, from June to September 2001. He was the chairman of the Department of Information Management at Chung Jung University from August 2000 to July 2003. Since August 2004, he has become a Full Professor at the Department of Information and Learning Technology, National University of Tainan, Tainan, Taiwan. Currently, he is the chairman of the Department of Information and Learning Technology, National University of Tainan. He co-received the best paper award of 2001 IEEE ICOIN-15. His current research interests include mobile computing and wireless networks, mobile learning, data mining, and pervasive computing. Dr. Chen is a member of the IEEE Computer Society. Chih-Ping Chu received the B.S. degree in agricultural chemistry from National Chung Hsing University, Taiwan, the M.S. degree in computer science from the University of California, Riverside, and the Ph.D. degree in computer science from Louisiana State University. He is currently a Professor in the Department of Computer Science and Information Engineering of National Cheng Kung University, Taiwan. His current research interests include parallel computing, parallel processing, component-based software development, and internet computing.     

A Location-Aware Routing Protocol for the Bluetooth Scatternet

Bluetooth is a most promising technology for the wireless personal area networks and its specification describes how to build a piconet. Though the construction of scatternet from the piconets is left out in the specification, some of the existing solutions discuss the scatternet formation issues and routing schemes. Routing in a scatternet, that has more number of hops and relay nodes increases the difficulties of scheduling and consumes the bandwidth and power resources and thereby impacts on the performance of the entire network. In this paper, a novel routing protocol (LARP) for the Bluetooth scatternet is proposed, which reduces the hop counts between the source and the destination and reconstructs the routes dynamically using the location information of the Bluetooth devices. Besides, a hybrid location-aware routing protocol (HLARP) is proposed to construct the shortest routes among the devices with or without having the location information and degenerate the routing schemes without having any location information. Experimental results show that our protocols are efficient enough to construct the shortest routing paths and to minimize the transmission delay, bandwidth and power consumption as compared to the other protocols that we have considered. Chih-Yung Chang received the Ph.D. degree in Computer Science and Information Engineering from National Central University, Taiwan, in 1995. He joined the faculty of the Department of Computer and Information Science at Aletheia University, Taiwan, as an Assistant Professor in 1997. He was the Chair of the Department of Computer and Information Science, Aletheia University, from August 2000 to July 2002. He is currently an Associate Professor of Department of Computer Science and Information Engineering at Tamkang University, Taiwan. Dr. Chang served as an Associate Guest Editor of Journal of Internet Technology (JIT, 2004), Journal of Mobile Multimedia (JMM, 2005), and a member of Editorial Board of Tamsui Oxford Journal of Mathematical Sciences (2001--2005). He was an Area Chair of IEEE AINA'2005, Vice Chair of IEEE WisCom 2005 and EUC 2005, Track Chair (Learning Technology in Education Track) of IEEE ITRE'2005, Program Co-Chair of MNSA'2005, Workshop Co-Chair of INA'2005, MSEAT'2003, MSEAT'2004, Publication Chair of MSEAT'2005, and the Program Committee Member of USW'2005, WASN'2005, and the 11th Mobile Computing Workshop. Dr. Chang is a member of the IEEE Computer Society, Communication Society and IEICE society. His current research interests include wireless sensor networks, mobile learning, Bluetooth radio systems, Ad Hoc wireless networks, and mobile computing. Prasan Kumar Sahoo got his Master degree in Mathematics from Utkal University, India. He did his M.Tech. degree in Computer Science from Indian Institute of Technology (IIT), Kharagpur, India and received his Ph.D in Mathematics from Utkal University, India in April, 2002. He joined in the Software Research Center, National Central University, Taiwan and currently working as an Assistant Professor, in the department of Information Management, Vanung University, Taiwan, since 2003. He was the Program Committee Member of MSEAT'2004, MSEAT'2005, WASA'2006, and IEEE AHUC'2006. His research interests include the coverage problems, modeling and performance analysis of wireless sensor network and Bluetooth technology. Shih-Chieh Lee received the B.S. degree in Computer Science and Information Engineering from Tamkang University, Taiwan, in 1997. Since 2003 he has been a Ph.D. Students in Department of Computer Science and Information Engineering, Tamkang University. His research interests are wireless sensor networks, Ad Hoc wireless networks, and mobile/wireless computing.     

Characteristic Investigation of New Pathological Elements

A characteristic investigation of the new pathological elements (i.e voltage mirror and current mirror) has been presented. Many nullor-mirror equivalences are explored. The circuit cascadability is discussed with nullor and mirror concepts. Also, the conventional inverse network transformation has been extended for applying to the circuits with current mirror output. To demonstrate the use of presented properties, practical examples have been given. The derived circuits have been verified with HSPICE simulation and the simulation results confirm with our theoretical prediction.Hung-Yu Wang was born in Kaohsiung, Taiwan, Republic of China, on January 4, 1969. He received the Ph.D. degree in optical sciences from National Central University, Chung-Li, Taiwan in 2002.Since 1993 he has worked on promoting the prototyping IC implementation of academic researches, and propelling the collaboration of the academia and industries in Chip Implementation Center (CIC), National Science Council of the Republic of China. In 2003 he became a researcher and the deputy director in Division of Chip Implementation Service of CIC. He is currently working on South Region Office of National Chip Implementation Center, National Applied Research Laboratories as a researcher and the department manager. His research interests are in current-mode circuits design, analog IC design and analog IP design.Ching-Ting Lee was born in Taoyuan, Taiwan, R.O.C., on November 1, 1949. He received his B.S. and M.S. in Electrical Engineering Department of the National Cheng-Kung University, Taiwan, in 1972 and 1974, respectively. He received Ph.D. degree in Electrical Engineering Department from the Carnegie-Mellon University, Pittsburgh, PA, in 1982.He worked on Chung Shan Institute of Science and Technology, before he joined the Institute of Optical Sciences, National Central University, Chung-Li, Taiwan, as a Professor in 1990. He works on National Cheng-Kung University as the dean of Electrical Engineering and Computer Science and the professor or the Institute of Microelectronics, Department of Electrical Engineering in 2003. His current research interests include theory, design, and application of guided-wave structures and devices for integrated optics and waveguide lasers. His research activities have also involved in the research concerning semiconductor lasers, photodetectors and high-speed electronic devices, and their associated integration for electrooptical integrated circuits. He received the outstanding Research Professor Fellowship from the National Science Council (NSC), R.O.C. in 2000 and 2002. He also received the Optical Engineering Medal from Optical Engineering Society and Distinguish Electrical Engineering professor award from Chinese Institute of Electrical Engineering Society in 2003.Chun-Yueh Huang was born in Taichung, Taiwan, Republic of China, on March 24, 1967. He received the B.S. degree in industrial education from National Chang Hwa Normal University, Chang Hwa, Taiwan in 1991, M.S. and Ph.D. degrees both in electrical engineering from the National Cheng Kung University, Tainan, Taiwan in 1993 and 1997, respectively. Since 1999 he has been with the Kan Shan University of Technology, where he is currently Associate Professor and Chairman of Department of Electronic Engineering. His biography is included in the 7th Edition (2003–2004) of Who’s Who in Science and Engineering.His current researches include current-mode circuits design, VLSI design, analog IC design and analog IP design.     

ZBP: A Zone-Based Broadcasting Protocol for Wireless Sensor Networks

Wireless Sensor Networks (WSNs) have been widely used in motoring and collecting interests of environment information. Packet flooding or broadcasting is an essential function for establishing a communication path from sink node to a region of sensor nodes. However, flooding operation consumes power and bandwidth resources and raises the packet collision and contention problems, which reduce the success rate of packet transmissions and consume energy. This article proposes an efficient broadcasting protocol to reduce the number of sensor nodes that forward the query request, hence improves the packet delivery rate and saves bandwidth and power consumptions. Sensor node that received the query request will dynamically transfers the coordinate system according to the zone-ID of source node and determines whether it would forward the request or not in a distributed manner. Compared with the CBM and traditional flooding operation, experimental results show that the proposed zone-based broadcasting protocol decreases the bandwidth and power consumptions, reduces the packet collisions, and achieves high success rate of packet broadcasting.Chih-Yung Chang received the Ph.D. degree in Computer Science and Information Engineering from National Central University, Taiwan, in 1995. He joined the faculty of the Department of Computer and Information Science at Aletheia University, Taiwan, as an Assistant Professor in 1997. He was the Chair of the Department of Computer and Information Science, Aletheia University, from August 2000 to July 2002. He is currently an Associate Professor of Department of Computer Science and Information Engineering at Tamkang University, Taiwan. Dr. Chang served as an Associate Guest Editor of Journal of Internet Technology (JIT), Special Issue on “Wireless Ad Hoc and Sensor Networks” (2004) and a member of Editorial Board of Tamsui Oxford Journal of Mathematical Sciences (2001–2005). He was an Area Chair of IEEE AINA′2005, Vice Chair of IEEE WisCom2005, Track Chair (Learning Technology in Education Track) of IEEE ITRE′2005, Program Co-Chair of MNSA′2005, Workshop Co-Chair of INA′2005, MSEAT′2003, MSEAT′2004, Publication Chair of MSEAT′2005, and the Program Committee Member of ICPP′2004, USW′2005, WASN′2005, and the 11th Mobile Computing Workshop. Dr. Chang is a member of the IEEE Computer Society and IEICE society. His current research interests include wireless sensor networks, mobile learning, Bluetooth radio systems, Ad Hoc wireless networks, and mobile computing.Kuei-Ping Shih received the B.S. degree in Mathematics from Fu-Jen Catholic University, Taiwan, Republic of China, in June 1991 and the Ph.D. degree in Computer Science and Information Engineering from National Central University, Taiwan, Republic of China, in June 1998. After two years of military obligation, he joined the faculty of the Department of Computer Science and Information Engineering, Tamkang University, Taiwan, Republic of China, as an assistant professor in 2000. Dr. Shih served as a Program Area Chair in the IEEE International Conference on Advanced Information Networking and Applications (AINA), 2005, and as a Technical Track Chair in the IEEE International Conference on Information Technology: Research and Education (ITRE), 2005. Dr. Shih’s current research interests include wireless networks, sensor networks, mobile computing, and network protocols design.Dr. Shih is a member of the IEEE Computer and Communication Societies and Phi Tau Phi Scholastic Honor Society.Shih-Chieh Lee received the B.S. degree in Computer Science and Information Engineering from Tamkang University, Taiwan, in 1997. Since 2003 he has been a Ph.D. Students in Department of Computer Science and Information Engineering, Tamkang University. His research interests are wireless sensor networks, Ad Hoc wireless networks, and mobile/wireless computing.     

An Improved GGSN Failure Restoration Mechanism for UMTS

Universal mobile telecommunications system (UMTS) provides packet-switched data services for mobile users. To efficiently deliver packets in the UMTS core network, the PDP contexts (i.e., the routing information) are maintained in the volatile storage (e.g., memory) of SGSN, GGSN, and UE. The GGSN routes packets between the UMTS core network and external data networks, and thus has heavy traffic and computation loading, which may result in PDP contexts lost or corrupted, and the QoS of the UMTS network may degrade significantly. To resolve this issue, 3GPP 23.007 proposes a mechanism for GGSN failure restoration. In this mechanism, the corrupted PDP contexts can be restored through the PDP Context Activation procedure. However, this incurs extra signaling cost to the network. To reduce the network signaling cost and delay for restoration of the corrupted PDP contexts, this paper proposes an improved mechanism “GGSN Failure Restoration” (GFR) with different backup algorithms. The analytic models and simulation experiments are conducted to evaluate GFR.Our study indicates that the GFR mechanism can significantly reduce the cost for the PDP context restoration. Phone Lin (M'02) received his BSCSIE degree and Ph.D. degree from National Chiao Tung University, Taiwan, R.O.C. in 1996 and 2001, respectively. From August 2001 to July 2004, he was an Assistant Professor in Department of Computer Science and Information Engineering (CSIE), National Taiwan University, R.O.C. Since August 2004, he has been an Associate Professor in Department of Computer Science and Information Engineering (CSIE), National Taiwan University, R.O.C. His current research interests include personal communications services, wireless Internet, and performance modeling. Dr. Lin is a Guest Editor for IEEE Wireless Communications special issue on Mobility and Resource Management. He is also an Associate Editorial Member for the WCMC Journal. Guan-Hua Tu received his B.S.C.S.I.E degree from National Central University, Taiwan, R.O.C., in 2001 and his Master degree in Computer Science from National Taiwan University, Taiwan, R.O.C., in 2003. He is currently a software engineer in MediaTek Inc. His resarch interests include personal communication services, mobile computing, and performance modeling.     

Design of Current-Mode Square-Root Domain Band-Pass Filter with Reduced Voltage

A design technique for current-mode square-root domain band-pass filter fabricated in a 0.25 μ m CMOS process is presented. The basic building block consists of current-mode current mirrors, square-root circuits and capacitors, and in which the overall supply voltage is reduced by adopting low-voltage level-shift current mirror. Both of the simulation and measured results, which are in good agreement, indicate that the prototype of the band-pass provides tunable center frequency of 4–10 MHz with bias-current-tunable, −26.7 dB total harmonic distortion (THD), and approximately 1.598 mW power dissipation with a 1.5 V supply voltage. Advantages of the proposed filter include high frequency operation, tuneability, low supply voltage operation, low power consumption, and low third order intermodulation distortion. Gwo-Jeng Yu was born in Kaohsiung, Taiwan, R.O.C., in 1954. He received the B.S. and M.S. degrees in the Department Electronic Engineering in 1972 and 1976, respectively, from National Chiao Tung University, HsinChu, Taiwan, R.O.C., and he is currently working toward the Ph.D. degree in the Department of Electrical Engineering of National Cheng Kung University, Tainan, Taiwan, R.O.C. Since 1978, he has been on the Faculty of Institute of Cheng Shiu Technology, Kaohsiung, Taiwan, R.O.C., where he is currently a Associate Professor in the Department of Electronic Engineering. During 1979–1990, he was the Chairman of the Electronic Engineering Department and the Chairman of the Microelectronics and Information Technology Center during 1996–2000. His current researches include current-mode circuits design, analog IC design and VLSI circuit design. Chun-Yueh Huang was born in Taichung, Taiwan, Republic of China, on March 24, 1967. He received the B.S. degree in industrial education from the National Chang Hwa Normal University, Chang Hwa, Taiwan in 1991, M.S. and Ph.D. degrees both in electrical engineering from the National Cheng Kung University, Tainan, Taiwan, in 1993 and 1997, respectively. Since 1999 he has been with the Kan Shan University of Technology, where he is currently Associate Professor and Chairman of the Department of Electronic Engineering. His current researches include current-mode circuits design, VLSI design, analog IC design, and analog IP design. Jenn-Jiun Chen received the B.S. and M.S. degrees both in electrical engineering from the National Cheng Kung University, Tainan, Taiwan, in 2001 and 2003, respectively. His research interests are design and modeling of current mode circuit, low power analog circuit design, current mode filters, and instrumental amplifier in micro sensor applications. He received Chip Design Award from the Chip Implementation Center, National Applied Research Laboratories, in 2002. Bin-Da Liu received the B.S., M.S., and Ph.D. degrees all in electrical engineering from the National Cheng Kung University, Tainan, Taiwan, in 1973, 1975, and 1983, respectively. Since 1977 he has been on the faculty of the National Cheng Kung University, where he is currently Distinguished Professor in the Department of Electrical Engineering and Director of the SoC Research Center. During 1983–1984, he was a Visiting Assistant Professor in the Department of Computer Science, University of Illinois at Urbana-Champaign. During 1988–1992, he was the Director of Electrical Laboratories, National Cheng Kung University. He was the Associate Chair of the Electrical Engineering Department during 1996–1999 and the Chair during 1999–2002. Since 1995 he has been a consultant of the Chip Implementation Center, National Applied Research Laboratories. He has published more than 190 technical papers. He also contributed chapters in the book Neural Networks and Systolic Array Design (D. Zhang Ed. Singapore: World Scientific Publisher, 2002) and the book Accuracy Improvements in Linguistic Fuzzy Modeling (J. Casillas, O. Cordn, F. Herrera, and L. Magdalena Eds. Heidelberg, Germany: Springer-Verlag, 2003). He is currently a CAS Associate Editor of the IEEE Circuits & Devices Magazine and an Associate Editor of the IEEE Transactions on Circuits and Systems-I. His current research interests include low power circuit design, SoC system integration and verification, and VLSI implementation for fuzzy-neural networks and audio/video signal processors.     

Concurrent Error Detection in a Polynomial Basis Multiplier over GF(2 m )

Eliminating cryptographic computation errors is vital for preventing attacks. A simple approach is to verify the correctness of the cipher before outputting it. The multiplication is the most significant arithmetic operation among the cryptographic computations. Hence, a multiplier with concurrent error detection ability is urgently necessary to avert attacks. Employing the re-computing shifted operand concept, this study presents a semi-systolic array polynomial basis multiplier with concurrent error detection with minimal area overhead. Moreover, the proposed multiplier requires only two extra clock cycles while traditional multipliers using XOR trees consume at least extra XOR gate delays in GF(2^m) fields. Chiou-Yng Lee received the Bachelor’s degree (1986) in medical engineering and the M.S. degree in electronic engineering (1992), both from the Chung Yuan university, Taiwan, and the Ph.D. degree in electrical engineering from Chang Gung University, Taiwan, in 2001. From 1988 to now, he was a research associate with Chunghwa Telecommunication Laboratory in Taiwan. He joined the department of project planning. He taught those related field courses at Ching-Yun Technology University. He is currently as an assistant professor of Department of Computer Information and Network Engineering in Lunghwa University of Science and Technology. His research interests include computations in finite fields, error-control coding, signal processing, and digital transmission system. Besides, he is a member of the IEEE and the IEEE Computer society. He is also an honor member of Phi Tao Phi in 2001. Che Wun Chiou received his B.S. degree in Electronic Engineering from Chung Yuan Christian University in 1982, the M.S. degree and the Ph.D. degree in Electrical Engineering from National Cheng Kung University in 1984 and 1989, respectively. From 1990 to 2000, he was with the Chung Shan Institute of Science and Technology in Taiwan. He joined the Department of Electronic Engineering and the Department of Computer Science and Information Engineering, Ching Yun University in 2000 and 2005, respectively. He is currently as Dean of Division of Continuing Education in Ching Yun University. His current research interests include fault-tolerant computing, computer arithmetic, parallel processing, and cryptography. Jim-Min Lin was born on March 5, 1963 in Taipei, Taiwan. He received the B.S. degree in Engineering Science and the M.S. and the Ph.D. degrees in Electrical Engineering, all from National Cheng Kung University, Tainan, Taiwan, in 1985, 1987, and 1992, respectively. Since February 1993, he has been an Associate Professor at the Department of Information Engineering and Computer Science, Feng Chia University, Taichung City, Taiwan. He is currently as Professor at the Department of Information Engineering and Computer Science, Feng Chia University. His research interests include Operating Systems, Software Integration/Reuse, Embedded Systems, Software Agent Technology, and Testable Design.     

Location-aware routing protocol with dynamic adaptation of request zone for mobile ad hoc networks

One possibility direction to assist routing in Mobile Ad Hoc Network (MANET) is to use geographical location information provided by positioning devices such as global positioning systems (GPS). Instead of searching the route in the entire network blindly, position-based routing protocol uses the location information of mobile nodes to confine the route searching space into a smaller estimated range. The smaller route searching space to be searched, the less routing overhead and broadcast storm problem will occur. In this paper, we proposed a location-based routing protocol called LARDAR. There are three important characteristics be used in our protocol to improve the performance. Firstly, we use the location information of destination node to predict a smaller triangle or rectangle request zone that covers the position of destination in the past. The smaller route discovery space reduces the traffic of route request and the probability of collision. Secondly, in order to adapt the precision of the estimated request zone, and reduce the searching range, we applied a dynamic adaptation of request zone technique to trigger intermediate nodes using the location information of destination node to redefine a more precise request zone. Finally, an increasing-exclusive search approach is used to redo route discovery by a progressive increasing search angle basis when route discovery failed. This progressive increased request zone and exclusive search method is helpful to reduce routing overhead. It guarantees that the areas of route rediscovery will never exceed twice the entire network. Simulation results show that LARDAR has lower routing cost and collision than other protocols. Tzay-Farn Shih was with Department of Electrical Engineering, National Taiwan University. Tzay-Farn Shih received the B.S. degree in Information Management from Chinese Culture University, Taiwan, in 1992, the M.S. degree in Computer Science Engineering from Tatung University, Taiwan, in 1996, and the Ph.D. degree in Electrical Engineering from National Taiwan University, Taiwan, in 2006. He is presently an assistant professor of Computer Science and Information Engineering at Chaoyang University of Technology, where he initially joined in August 2006. He is currently an overseas member of the Institute of Electronics, Information and Communication Engineers (IEICE). His current research interests include computer simulation, computer networks routing protocol, wireless networks, Mobile Ad Hoc networks and sensor networks. Hsu-Chun Yen was born in Taiwan, Republic of China, on May 29, 1958. He received the B.S. degree in electrical engineering from National Taiwan University, Taiwan, in 1980, the M.S. degree in computer engineering from National Chiao-Tung University, Taiwan, in 1982, and the Ph.D. degree in computer science from the University of Texas at Austin, U.S.A., in 1986. He is presently a Professor of Electrical Engineering at National Taiwan University, where he initially joined in August 1990. From August 1986 to July 1990, he was an Assistant Professor of Computer Science at Iowa State University, Ames, Iowa, U.S.A. His current research interests include Petri net theory, formal methods, design and analysis of algorithms, and complexity theory. Dr. Yen is an editor of International Journal of Foundations of Computer Science (IJFCS, World Scientific Publisher).     

Design of Square-Root Domain Filters

In this paper, a square-root domain band-pass filter and biquad filter which are based on the MOSFET square law are proposed. Both of the square-root domain filters operated at 2.5 V supply voltage are constituted by current mirrors, current-mode square-root circuits and capacitors. The circuits presented have been simulated and fabricated using 0.25 m CMOS process. Both of simulation and measured results which are in good agreement indicate that the center frequency f₀ is not only attainable at megahertz frequencies but also tunable electronically. The proposed circuits have the merits of high frequency operation, tuneability, low power supply voltage operation, low third order intermodulation distortion and low total harmonic distortion.Gwo-Jeng Yu was born in Kaohsiung, Taiwan, R.O.C., in 1954. He received the B.S. and M.S. degrees in the Department Electronic Engineering in 1972 and 1976, respectively, from National Chiao Tung University, HsinChu, Taiwan, R.O.C., and he is currently working toward the Ph.D. degree in the Department of Electrical Engineering of National Cheng Kung University, Tainan, Taiwan, R.O.C.Since 1978, he has been on the Faculty of Institute of Cheng Shiu Technology, Kaohsiung, Taiwan, R.O.C., where he is currently a Associate Professor in the Department of Electronic Engineering. During 1979–1990, he was the Chairman of the Electronic Engineering Department and the Chairman of the Microelectronics and Information Technology Center during 1996–2000.His current researches include current-mode circuits design, analog IC design and VLSI circuit design.Chun-Yueh Huang was born in Taichung, Taiwan, Republic of China, on March 24, 1967. He received the B.S. degree in industrial education from the National Chang Hwa Normal University, Chang Hwa, Taiwan in 1991, M.S. and Ph.D. degrees both in electrical engineering from the National Cheng Kung University, Tainan, Taiwan, in 1993 and 1997, respectively. Since 1999 he has been with the Kan Shan University of Technology, where he is currently Associate Professor and Chairman of the Department of Electronic Engineering. His current researches include current-mode circuits design, VLSI design, analog IC design, and analog IP design.Bin-Da Liu received the B.S., M.S., and Ph.D. degrees all in electrical engineering from the National Cheng Kung University, Tainan, Taiwan, in 1973, 1975, and 1983, respectively.Since 1977 he has been on the faculty of the National Cheng Kung University, where he is currently Distinguished Professor in the Department of Electrical Engineering and Director of the SoC Research Center. During 1983–1984, he was a Visiting Assistant Professor in the Department of Computer Science, University of Illinois at Urbana-Champaign. During 1988–1992, he was the Director of Electrical Laboratories, National Cheng Kung University. He was the Associate Chair of the Electrical Engineering Department during 1996–1999 and the Chair during 1999–2002. Since 1995 he has been a consultant of the Chip Implementation Center, National Applied Research Laboratories. He has published more than 190 technical papers. He also contributed chapters in the book Neural Networks and Systolic Array Design (D. Zhang, Ed. Singapore: World Scientific Publisher, 2002) and the book Accuracy Improvements in Linguistic Fuzzy Modeling (J. Casillas, O. Cordón, F. Herrera, and L. Magdalena, Eds. Heidelberg, Germany: Springer-Verlag, 2003). He is currently a CAS Associate Editor of the IEEE Circuits {&} Devices Magazine and an Associate Editor of the IEEE Transactions on Circuits and Systems-I. His current research interests include low power circuit design, SoC system integration and verification, and VLSI implementation for fuzzy-neural networks and audio/video signal processors.Jenn-Jiun Chen received the B.S. and M.S. degrees both in electrical engineering from the National Cheng Kung University, Tainan, Taiwan, in 2001 and 2003, respectively. His research interests are design and modeling of current mode circuit, low power analog circuit design, current mode filters, and instrumental amplifier in micro sensor applications. He received Chip Design Award from the Chip Implementation Center, National Applied Research Laboratories, in 2002.     

The Coverage Problem in a Wireless Sensor Network

One of the fundamental issues in sensor networks is the coverage problem, which reflects how well a sensor network is monitored or tracked by sensors. In this paper, we formulate this problem as a decision problem, whose goal is to determine whether every point in the service area of the sensor network is covered by at least k sensors, where k is a given parameter. The sensing ranges of sensors can be unit disks or non-unit disks. We present polynomial-time algorithms, in terms of the number of sensors, that can be easily translated to distributed protocols. The result is a generalization of some earlier results where only k = 1 is assumed. Applications of the result include determining insufficiently covered areas in a sensor network, enhancing fault-tolerant capability in hostile regions, and conserving energies of redundant sensors in a randomly deployed network. Our solutions can be easily translated to distributed protocols to solve the coverage problem.A preliminary version of this paper has appeared in the Workshop on Wireless Sensor Networks and Applications, 2003, San Diego, CA, USA. Chi-Fu Huang received his B.S. and M.S. degrees both in Computer Science and Information Engineering from the Feng-Chia University and the National Central University in 1999 and 2001, respectively. He obtained his Ph.D. in the Department of Computer Science and Information Engineering from the National Chiao-Tung University in September of 2004. He is currently a Research Assistant Professor at the Department of Computer Science and Information Engineering, National Chiao-Tung University, Taiwan. His research interests include wireless communication and mobile computing, especially in ad hoc and sensor networks. Yu-Chee Tseng received his B.S. and M.S. degrees in Computer Science from the National Taiwan University and the National Tsing-Hua University in 1985 and 1987, respectively. He worked for the D-LINK Inc. as an engineer in 1990. He obtained his Ph.D. in Computer and Information Science from the Ohio State University in January of 1994. He was an Associate Professor at the Chung-Hua University (1994–1996) and at the National Central University (1996–1999), and a Full Professor at the National Central University (1999–2000). Since 2000, he has been a Full Professor at the Department of Computer Science and Information Engineering, National Chiao-Tung University, Taiwan. Dr. Tseng served as a Program Chair in the Wireless Networks and Mobile Computing Workshop, 2000 and 2001, as a Vice Program Chair in the Int’l Conf. on Distributed Computing Systems (ICDCS), 2004, as a Vice Program Chair in the IEEE Int’l Conf. on Mobile Ad-hoc and Sensor Systems (MASS), 2004, as an Associate Editor for The Computer Journal, as a Guest Editor for ACM Wireless Networks special issue on “Advances in Mobile and Wireless Systems”, as a Guest Editor for IEEE Transactions on Computers special on “Wireless Internet”, as a Guest Editor for Journal of Internet Technology special issue on “Wireless Internet: Applications and Systems”, as a Guest Editor for Wireless Communications and Mobile Computing special issue on “Research in Ad Hoc Networking, Smart Sensing, and Pervasive Computing”, as an Editor for Journal of Information Science and Engineering, as a Guest Editor for Telecommunication Systems special issue on “Wireless Sensor Networks”, and as a Guest Editor for Journal of Information Science and Engineering special issue on “Mobile Computing”. He is a two-time recipient of the Outstanding Research Award, National Science Council, ROC, in 2001–2002 and 2003–2005, and a recipient of the Best Paper Award in Int’l Conf. on Parallel Processing, 2003. Several of his papers have been chosen as Selected/Distinguished Papers in international conferences. He has guided students to participate in several national programming contests and received several awards. His research interests include mobile computing, wireless communication, network security, and parallel and distributed computing. Dr. Tseng is a member of ACM and a Senior Member of IEEE.This revised version was published online in August 2005 with a corrected cover date.