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.     

On Striping Traffic over Multiple IEEE 802.11(b) Wireless Channels

Due to interference, path loss, multipath fading, background noise, and many other factors, wireless communication normally cannot provide a wireless link with both a high data rate and a long transmission range. To address this problem, striping network traffic in parallel over multiple lower-data-rate but longer-transmission-range wireless channels may be used. In this paper, we propose a new striping method and evaluate its performances over multiple IEEE 802.11(b) channels under various conditions. Our extensive simulation results show that this method is quite effective for such an application. S.Y. Wang is an Associate Professor of the Department of Computer Science and Information Engineering at National Chiao Tung University, Taiwan. He received his Master and Ph.D. degree in computer science from Harvard University in 1997 and 1999, respectively. His research interests include wireless networks, Internet technologies, network simulations, and operating systems. He is the author of the NCTUns 2.0 network simulator and emulator, which is being widely used by network and communication researchers. More information about the tool is available at http://NSL.csie.nctu.edu.tw/nctuns.html. C.H. Hwang received his master degree in computer science from NCTU in 2002 and currently is working for a network company. C.L. Chou currently is a third-year Ph.D. student at the Department of Computer Science and Information Engineering, National Chiao TungUniversity (NCTU), Taiwan. He received his master degree in computer science from NCTU in 2002.     

A Relay-Based MAC Protocol for Multi-Rate and Multi-Range Infrastructure Wireless LANs

Auto rate adaptation mechanisms have been proposed to improve the throughput in wireless local area networks with IEEE 802.11a/b/g standards that can support multiple data rate at the physical layer. However, even with the capability of transmitting multi-packets with multi-rate IEEE 802.11 PHY, a mobile host near the fringe of the Access-Point's (AP's) transmission range still needs to adopt a low-level modulation to cope with the lower signal-to-noise ratio (SNR), Thus, it can not obtain a data rate as high as that of a host near AP in most cases. According to the characteristics of modulation schemes, the highest data rate between a pair of mobile hosts will be inversely proportional with the transmission distance. Considering these factors, we here demonstrate a Relay-Based Adaptive Auto Rate (RAAR) protocol that can find a suitable relay node for data transmission between transmitter and receiver, and can dynamically adjust its modulation scheme to achieve the maximal throughput of a node according to the transmission distance and the channel condition. The basic concept is that the best modulation schemes are adaptively used by a wireless station to transmit an uplink data frame, according to the path loss condition between the station itself and a relay node, and that between the relay node and AP, thus delivering data at a higher overall data rate. Evaluation results show that this scheme provides significant throughput improvement for nodes located at the fringe of the AP's transmission range, thus remarkably improving overall system performance. Jain-Shing Liu was born in Taipei, Taiwan, in 1970. He received the Ph.D. degree in Department of Computer and Information Science, National Chiao Tung University, Hsinchu, Taiwan. He is currently with the faculty of the Department of Computer Science and Information Management, Providence University, Taichung, Taiwan 433, ROC. His research interests include wireless communication protocol design, performance analysis and modeling, personal communication networks, and distributed simulation. Dr. Liu is a member of IEEE and IEICE. Chunhung Richard Lin was born in Kaohsiung, Taiwan. He received the B.S. and M.S. degrees from the Department of Computer Science and Information Engineering, National Taiwan University, in 1987 and 1989, respectively, and the Ph.D. degree from Computer Science Department, University of California, Los Angeles (UCLA), in 1996. Dr. Lin joined National Chung Cheng University in Taiwan in 1996. Since August 2000, he has been with the Department of Computer Science and Engineering, National Sun Yat-Sen University, Kaohsiung, Taiwan. His research interests include the design and control of personal communication networks, protocol design and implementation for differentiated/integrated services in mobile wireless networks, mobile Internet, distributed simulation, and embedded operating system design and implementation. His email address is: lin@cse.nsysu.edu.tw. Dr. Lin is an ACM member. He received the 2001 Junior Professor Research Award from National Sun Yat-Sen University and the 2000 Investigative Research Award from the Pan Wen Yuan Foundation, Taiwan, ROC.     

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.     

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.     

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.     

BER Performance of Wireless BPSK Communication System in Tunnels With and Without Traffic

The bit error rate (BER) performance for high-speed personal communication service in tunnels with and without traffic is investigated. The impulse responses of tunnels for any transmitter–receiver location are computed by shooting and bouncing ray/image techniques. By using the impulse responses of these multipath channels, the BER performance of BPSK (binary phase shift keying) system with phase and timing recovery circuits are calculated. Numerical results have shown that the multipath effect by the vehicles in the tunnel is an important factor for BER performance. In addition, the effect of space diversity techniques and decision feedback equalizer on mitigating the multipath fading is also investigated.Chien-Hung Chen was born in Kaohsiung, Taiwan, Republic of China, on 8 March 1971. He received the MSEE degree from Tamkang University in 1999. He is studying for Ph.D. degree in the Department of Electrical Engineering, Tamkang University. His current research interests include indoor wireless communications and numerical techniques in electromagnetics.Chien-Ching Chiu was born in Taoyuan, Taiwan, Republic of China, on 23 January 1963. He received the BSCE degree from National Chiao Tung University, Hsinchu, Taiwan, in 1985 and MSEE and PhD degrees from National Taiwan University, Taipei, Taiwan, in 1987 and 1991, respectively. From 1987 to1989, he served in the ROC Army Force as a communication officer. In 1992 he joined the faculty of the Department of Electrical Engineering, Tamkang University, where he is now an Professor. He was a visiting scholar at the MIT and University of Illinois, Urbana from 1998 to 1999. His current research interests include microwave imaging, numerical techniques in electromagnetics and indoor wireless communications.Shi-Cheng Hung received the MSEE degree from Tamkang University in 1998. He is now a RF engineer. His current research interests include indoor wireless communications and numerical techniques in electromagnetics.Chien-Hung Lin received the MSEE degree from Tamkang University in 2001. He is now a RF engineer. His current research interests include indoor wireless communications and numerical techniques in electromagnetics.     

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.     

Scheduling Sleeping Nodes in High Density Cluster-based Sensor Networks

In order to conserve battery power in very dense sensor networks, some sensor nodes may be put into the sleep state while other sensor nodes remain active for the sensing and communication tasks. In this paper, we study the node sleep scheduling problem in the context of clustered sensor networks. We propose and analyze the Linear Distance-based Scheduling (LDS) technique for sleeping in each cluster. The LDS scheme selects a sensor node to sleep with higher probability when it is farther away from the cluster head. We analyze the energy consumption, the sensing coverage property, and the network lifetime of the proposed LDS scheme. The performance of the LDS scheme is compared with that of the conventional Randomized Scheduling (RS) scheme. It is shown that the LDS scheme yields more energy savings while maintaining a similar sensing coverage as the RS scheme for sensor clusters. Therefore, the LDS scheme results in a longer network lifetime than the RS scheme. Jing Deng received the B.E. and M.E. degrees in Electronic Engineering from Tsinghua University, Beijing, P. R. China, in 1994 and 1997, respectively, and the Ph.D. degree in Electrical and Computer Engineering from Cornell University, Ithaca, NY, in 2002. Dr. Deng is an assistant professor in the Department of Computer Science at the University of New Orleans. From 2002 to 2004, he visited the CASE center and the Department of Electrical Engineering and Computer Science at Syracuse University, Syracuse, NY as a research assistant professor, supported by the Syracuse University Prototypical Research in Information Assurance (SUPRIA) program. He was a teaching assistant from 1998 to 1999 and a research assistant from 1999 to 2002 in the School of Electrical and Computer Engineering at Cornell University. His interests include mobile ad hoc networks, wireless sensor networks, wireless network security, energy efficient wireless networks, and information assurance. Wendi B. Heinzelman is an assistant professor in the Department of Electrical and Computer Engineering at the University of Rochester. She received a B.S. degree in Electrical Engineering from Cornell University in 1995 and M.S. and Ph.D. degrees in Electrical Engineering and Computer Science from MIT in 1997 and 2000 respectively. Her current research interests lie in the areas of wireless communications and networking, mobile computing, and multimedia communication. Dr. Heinzelman received the NSF Career award in 2005 for her work on cross-layer optimizations for wireless sensor networks, and she received the ONR Young Investigator award in 2005 for her research on balancing resource utilization in wireless sensor networks. Dr. Heinzelman was co-chair of the 1st Workshop on Broadband Advanced Sensor Networks (BaseNets '04), and she is a member of Sigma Xi, the IEEE, and the ACM. Yunghsiang S. Han was born in Taipei, Taiwan, on April 24, 1962. He received the B.S. and M.S. degrees in electrical engineering from the National Tsing Hua University, Hsinchu, Taiwan, in 1984 and 1986, respectively, and the Ph.D. degree from the School of Computer and Information Science, Syracuse University, Syracuse, NY, in 1993. From 1986 to 1988 he was a lecturer at Ming-Hsin Engineering College, Hsinchu, Taiwan. He was a teaching assistant from 1989 to 1992 and from 1992 to 1993 a research associate in the School of Computer and Information Science, Syracuse University. From 1993 to 1997 he was an Associate Professor in the Department of Electronic Engineering at Hua Fan College of Humanities and Technology, Taipei Hsien, Taiwan. From 1997 to 2004 he was with the Department of Computer Science and Information Engineering at National Chi Nan University, Nantou, Taiwan. He was promoted to Full Professor in 1998. From June to October 2001 he was a visiting scholar in the Department of Electrical Engineering at University of Hawaii at Manoa, HI, and from September 2002 to January 2004 he was the SUPRIA visiting research scholar in the Department of Electrical Engineering and Computer Science and CASE center at Syracuse University, NY. He is now with the Graduate Institute of Communication Engineering at National Taipei University, Taipei, Taiwan. His research interests are in wireless networks, security, and error-control coding. Dr. Han is a winner of 1994 Syracuse University Doctoral Prize. Pramod K. Varshney was born in Allahabad, India on July 1, 1952. He received the B.S. degree in electrical engineering and computer science (with highest honors), and the M.S. and Ph.D. degrees in electrical engineering from the University of Illinois at Urbana-Champaign in 1972, 1974, and 1976 respectively. Since 1976 he has been with Syracuse University, Syracuse, NY where he is currently a Professor of Electrical Engineering and Computer Science and the Research Director of the New York State Center for Advanced Technology in Computer Applications and Software Engineering. His current research interests are in distributed sensor networks and data fusion, detection and estimation theory, wireless communications, intelligent systems, signal and image processing, and remote sensing he has published extensively. He is the author of Distributed Detection and Data Fusion, published by Springer-Verlag in 1997 and has co-edited two other books. Dr. Varshney is a member of Tau Beta Pi and is the recipient of the 1981 ASEE Dow Outstanding Young Faculty Award. He was elected to the grade of Fellow of the IEEE in 1997 for his contributions in the area of distributed detection and data fusion. In 2000, he received the Third Millennium Medal from the IEEE and Chancellor's Citation for exceptional academic achievement at Syracuse University. He serves as a distinguished lecturer for the AES society of the IEEE. He is on the editorial board Information Fusion. He was the President of International Society of Information Fusion during 2001.     

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.     

Theoretical Analysis and Performance of NC-PRMA Protocol for Multichannel Wireless Networks

In this paper, we analyze the effect of duplexing schemes on the throughput and the average packet dropping probability of a new multichannel wireless access protocol which allows for non-collision packet reservation multiple access with multiple channel (NC-PRMA/MC). N _C equal-capacity, orthogonal, traffic channels are shared by M mobile users on the uplink. Transmission attempts on the uplink are made by using time-frequency signaling in every frame, which enables transmission attempts of mobile users to be conveyed to the base station without collisions. Two kinds of duplexing schemes, frequency division duplexing and shared time division duplexing, are considered in the performance analysis. Using a discrete-time Markov chain analysis, we derive the analytic expressions for the average per channel throughput and the average packet dropping probability. Computer simulation results verify the analysis. Analytical evaluation and computer simulation show that NC-PRMA/MC with shared time division duplexing improves the channel capacity, which approaches the theoretical upper bound. Jenn-Kaie Lain born in Taiwan, R.O.C., in 1973. He received the B.E. degree in engineering science from the National Cheng Kung University, Tainan, Taiwan, R.O.C., and the Ph.D. degree in electrical engineering from the National Chung Cheng University, Chiayi, R.O.C., in 1995 and 2001, respectively. Since August 2001, he joined the faculty of Department of Computer Science and Information Engineering at Shu-Te University, Kaohsiung, Taiwan, R.O.C., as an Assistant Professor. He has been on the Faculty at National Yunlin University of Science and Technology, Yunlin, Taiwan, R.O.C., since August 2002 and currently holds the position of Assistant Professor in the Institute of Electronic and Information Engineering. His current research interest is in the field of coding and modulation as well as efficient receiver designs for broadband wireless communications. Jyh-HorngWen received his B.S. degree in Electronic Engineering from the National Chiao Tung University, Hsing-Chu, Taiwan, in 1979 and the Ph.D. degree in Electrical Engineering from the National Taiwan University, Taipei, in 1990. From 1981 to 1983, he was a Research Assistant with the Telecommunication Laboratory, Ministry of Transportation and Communications, Chung-Li, Taiwan. From 1983 to 1991, he was a Research Assistant with the Institute of Nuclear Energy Research, Taoyun, Taiwan. Since February 1991, he has been with the Institute of Electrical Engineering, National Chung Cheng University, Chia-Yi, Taiwan, first as an Associate Professor and, since 2000, as a Professor. He was also the Managing Director of the Center for Telecommunication Research, National Chung Cheng University, from Aug. 2000 to July 2004. Currently, he is also the Dean of General Affairs, National Chi Nan University. He is an Associate Editor of the Journal of the Chinese Grey System Association. His current research interests include computer communication networks, cellular mobile communications, personal communications, spread-spectrum techniques, wireless broadband systems, and gray theory. Prof.Wen is a member of the IEEE Communication Society, the IEEE Vehicular Technology Society, the International Association of Science and Technology for Development,the Chinese Grey System Association, and the Chinese Institute of Electrical Engineering.     

HISNs: Distributed gateways for application-level integration of heterogeneous wireless networks

Integration of different kinds of wireless networks to provide people seamless and continuous network access services is a major issue in the B3G network. In this paper, we propose and implement a novel Heterogeneous network Integration Support Node design (HISN) and a distributed HISN network architecture for the integration of heterogeneous networks, under which the Session Mobility, Personal Mobility, and Terminal Mobility for mobile users can be maintained through the Session Management mechanism. Thus, the HISN node can serve as an agent for the user to access Internet services independent of underlying communication infrastructure. Our design is transparent to the bearer networks and the deployment of the HISN network does not need to involve the operators of the heterogeneous wireless networks. This paper is an extension of the work that won the championship of the Mobile Hero contest sponsored by Industrial Development Bureau of Ministry of Economic Affairs, Taiwan, R.O.C., and was awarded USD 30,000. The work of Lin, Chang and Cheng was supported in part by the National Science Council (NSC), R.O.C, under the contract number NSC94-2213-E-002-083 and NSC94-2213-E-002-090, and NSC 94-2627-E-002-001, Ministry of Economic Affairs (MOEA), R.O.C., under contract number 93-EC-17-A-05-S1-0017, the Computer and Communications Researches Labs/Industrial Technology Research Institute (CCL/ITRL), Chunghwa Telecom Labs, Telcordia Applied Research Center, Taiwan Network Information Center (TWNIC), and Microsoft Corporation, Taiwan. The work of Fang was supported in part by the US National Science Foundation Faculty Early Career Development Award under grant ANI-0093241 and US National Science Foundation under grant DBI-0529012. 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 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. P. Lin’s email and website addresses are plin@csie.ntu.edu.tw and http://www.csie.ntu.edu.tw/∼plin, respectively. Huan-Ming Chang received the BSCSIE degree and Master CSIE degree from National Taiwan University, R.O.C. in 2003 and 2005, respectively. His current research interest includes wireless Internet. H.-M. Chang’s email address is r91114@csie.ntu.edu.tw. Yuguang Fang received a Ph.D. degree in Systems and Control Engineering from Case Western Reserve University in January 1994, and a Ph.D. degree in Electrical Engineering from Boston University in May 1997. From June 1997 to July 1998, he was a Visiting Assistant Professor in Department of Electrical Engineering at the University of Texas at Dallas. From July 1998 to May 2000, he was an Assistant Professor in the Department of Electrical and Computer Engineering at New Jersey Institute of Technology. In May 2000, he joined the Department of Electrical and Computer Engineering at University of Florida where he got the early promotion to Associate Professor with tenure in August 2003 and to Full Professor in August 2005. He has published over 180 papers in refereed professional journals and conferences. He received the National Science Foundation Faculty Early Career Award in 2001 and the Office of Naval Research Young Investigator Award in 2002. He is currently serving as an Editor for many journals including IEEE Transactions on Communications, IEEE Transactions on Wireless Communications, IEEE Transactions on Mobile Computing, and ACM Wireless Networks. He is also actively participating in conference organization such as the Program Vice-Chair for IEEE INFOCOM’2005, Program Co-Chair for the Global Internet and Next Generation Networks Symposium in IEEE Globecom’2004 and the Program Vice Chair for 2000 IEEE Wireless Communications and Networking Conference (WCNC’2000). Shin-Ming Cheng received the BSCSIE degree in 2000 from National Taiwan University, Taiwan, R.O.C., where he is currently working toward the Ph.D. degree in the Department of Computer Science and Information Engineering, National Taiwan University. His current research interests include mobile computing, personal communications services, and wireless Internet. S.-M. Cheng’s email and website addresses are shimi@pcs.csie.ntu.edu.tw and http://www.pcs.csie.ntu.edu.tw/∼shimi, respectively.     

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.     

Feedback Closed-Loop Scheduling Discipline for QoS Guarantee in Mobile Applications

Multi-functional and high-quality services are indispensable for providing responsive information services in a highly interactive e-learning system. This work presents a problem-solving mechanism using closed-loop scheduling discipline to achieve QoS e-learning applications. In the closed-loop schedule, the feedback mechanism supports wireless mobile communications services with dynamic QoS requirements. This work presents a closed-loop architecture by cascading the open-loop schedule, the QoS probe, the Proportional-Integral-Derivative (PID) controller and the feedback mechanism. In this architecture, the relationship between input and output is defined using a Lagrange λ-calculus module. The module estimates the future QoS according to the current scheduling, while the controller parameters are tuned according to the system status to achieve dynamic scheduling. Simulation results with e-learning activities demonstrate that the closed-loop schedule outperforms existing disciplines in terms of service delay and system utilization. Jiann-Liang Chen was born in Taiwan on December 15, 1963. He received the Ph.D. degree in Electrical Engineering from National Taiwan University, Taipei, Taiwan in 1989. Since August 1997, he has been with the Department of Computer Science and Information Engineering of National Dong Hwa University, where he is a professor now. His current research interests are directed at Wireless Sensor Networks, Cellular Mobility Management and Personal Communication Systems. Nong-Kun Chen received MS degree in Computer Science and Information Engineering, from the National Dong Hwa University, Hualien, Taiwan, in 2000. He is currently a doctoral student in the Department of Computer Science and Information Engineering at the National Dong Hwa University. His main research focuses on the areas of mobile cellular networks and feedback control.     

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.     

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.     

Update Propagation Algorithms for Supporting Disconnected Write in Mobile Wireless Systems with Data Broadcasting Capability

We develop and analyze algorithms for propagating updates by mobile hosts in wireless client–server environments that support disconnected write operations, with the goal of minimizing the tuning time for update propagation to the server. These algorithms allow a mobile host to update cached data objects while disconnected and propagate the updates to the server upon reconnection for conflict resolutions. We investigate two algorithms applicable to mobile systems in which invalidation reports/data can be broadcast to mobile hosts periodically. We show that there exists an optimal broadcasting period under which the tuning time is minimized for update propagations. We perform a comparative analysis between these two update propagation algorithms that rely on broadcasting data and an algorithm that does not, and identify conditions under which an algorithm should be applied to reduce the total tuning time for update propagation by the mobile user to save the valuable battery power and avoid high communication cost. For real-time applications, we address the tradeoff between tuning time and access time with the goal to select the best update propagation algorithm that can minimize the tuning time while satisfying the imposed real-time deadline constraint. The analysis result is applicable to file/data objects that mobile users may need to modify while on the move. Ing-Ray Chen received the BS degree from the National Taiwan University, Taipei, Taiwan, and the MS and PhD degrees in computer science from the University of Houston. He is currently an associate professor in the Department of Computer Science at Virginia Tech. His research interests include mobile computing, pervasive computing, multimedia, distributed systems, real-time intelligent systems, and reliability and performance analysis. Dr. Chen has served on the program committee of numerous conferences, including as program chair for 29th IEEE Annual International Computer Software and Application Conference in 2005, 14th IEEE International Conference on Tools with Artificial Intelligence in 2002, and 3rd IEEE Symposium on Application-Specific Systems and Software Engineering Technology in 2000. Dr. Chen currently serves as an Associate Editor for IEEE Transactions on Knowledge and Data Engineering, The Computer Journal, and International Journal on Artificial Intelligence Tools. He is a member of the IEEE/CS and ACM. Ngoc Anh Phan received her Bachelor of Science degree from Moscow Technical University of Communication and Computer Science in 1997, and a Master of Science degree in Computer Science from Virginia Polytechnic Institute and State University (Virginia Tech) in 1999. She is currently a Ph.D student at Virginia Tech and a Senior Software Engineer at America Online Inc. Her research interests include wireless communications, data management, sensor networks, fault tolerance, and mobile computing. I-Ling Yen received her BS degree from Tsing-Hua University, Taiwan, and her MS and PhD degrees in Computer Science from the University of Houston. She is currently an Associate Professor of Computer Science at the University of Texas at Dallas. Dr. Yen's research interests are in distributed systems, fault-tolerant computing, self-stabilization algorithms, and security. She has served as program co-chair for the 1997 IEEE High Assurance Systems Engineering Workshop, the 1999 IEEE Symposium on Application-Specific Systems and Software Engineering Technology, and the 1999 Annual IEEE International Conference on Computer Software and Applications Conference. Dr. Yen is a member of the IEEE/CS.     

A new pipelined analog-to-digital converter using current conveyors

A new pipelined analog-to-digital converter (ADC) using second-generation current conveyor (CCII) is presented. Two main building blocks of the pipelined ADC, sample-and-hold (S/H) circuit and multiplying digital-to-analog converter (MDAC) are constructed of CCII instead of operational amplifier (OA). Experimental results show that the proposed CCII-based pipelined ADC can work at 12.5 MHz with a 7.3-bit resolution. The DNL is within −0.4 LSB and 0.4 LSB and INL is within −0.8 LSB and 0.8 LSB, respectively. The pipelined ADC is realized in TSMC 0.35 μm CMOS technology and consumes 29 mW under a 3.3 V power supply. The core size is 0.85×0.85 mm². Sing-Yen Wu received the M.S. degree in the Department of Electronic Engineering from National Taipei University of Technology, Taipei, Taiwan, in 2005. His current research interests include CMOS pipelined analog-to-digital converters and mixed-signal integrated circuit. Lu-Po Liao received the M.S. degree in the Department of Electronic Engineering from National Taipei University of Technology, Taipei, Taiwan, in 2003. His current research interests include analog integrated circuit design and mixed-signal integrated circuit design. Chia-Chun Tsai received the Ph.D. degrees in Electrical Engineering from National Taiwan University, Taipei, Taiwan, 1991. From 1989 to 2005, he served at the Department of Electronic Engineering, National Taipei University of Technology, Taipei, Taiwan. Since 2005 he has been with the Department of Computer Science and Information Engineering, Nanhua University, Chiayi, Taiwan, where he is a Full Professor. His current research interests include VLSI design automation and mixed-signal IC designs.     

DAWL: A Delayed-ACK Scheme for MAC-Level Performance Enhancement of Wireless LANs

The IEEE 802.11 MAC protocol provides a reliable link layer using Stop & Wait ARQ. The cost for high reliability is the overhead due to acknowledgement packets in the direction opposite to the actual data flow. In this paper, the design of a new protocol as an enhancement of IEEE 802.11 is proposed, with the aim of reducing supplementary traffic overhead and increasing the bandwidth available for actual data transmission. The performance of the proposed protocol is evaluated through comparison with IEEE 802.11 as well as with a SSCOP-based protocol. Results underline significant advantages of the proposed protocol against existing ones, thus confirming the value and potentiality of the approach.Dzmitry Kliazovich received his Masters degree in telecommunication science from Belarusian State University of Informatics and Radioelectronics in 2002. He is currently working towards the Ph.D. degree in University of Trento, Italy. His main research interest lies in wireless networking field with a focus on performance optimization and cross-layer design.Fabrizio Granelli was born in Genoa in 1972. He received the “Laurea” (M.Sc.) degree in Electronic Engineering from the University of Genoa, Italy, in 1997, with a thesis on video coding, awarded with the TELECOM Italy prize, and the Ph.D. degree in Electronic Engineering and Computer Science from the same university in 2001. Since 2000 he is carrying on his teaching activity as Assistant Professor at the Dept. of Information and Communication Technologies (DIT) of the University of Trento (Italy) within the B.Sc. and M.Sc. Degrees in Telecommunications Engineering.The research interests of Dr. Granelli are mainly focused on networking, with particular attention to network modeling and performance evaluation, wireless networks, access control, and next-generation telecommunication networks.He is author of more than 30 refereed papers, published in several international journals and conferences.Dr. Granelli is member of the IEEE Committee on “Communication Systems Integration and Modeling” (CSIM) and of the Technical Programme Committee of the “QoS and Performance Evaluation Symposium” of the International Conference on Communications (ICC 2003 and ICC 2004).