A randomized energy-conservation protocol for resilient sensor networks*

In this paper we present PEAS, a randomized energy-conservation protocol that seeks to build resilient sensor networks in the presence of frequent, unexpected node failures. PEAS extends the network lifetime by maintaining a necessary set of working nodes and turning off redundant ones, which wake up after randomized sleeping times and replace failed ones when needed. The fully localized operations of PEAS are based on each individual node's observation of its local environment but do not require per neighbor state at any node; this allows PEAS to scale to very dense node deployment. PEAS is highly robust against node failures due to its simple operations and randomized design; it also ensures asymptotic connectivity. Our simulations and analysis show that PEAS can maintain an adequate working node density in presence of as high as 38% node failures, and a roughly constant overhead of less than 1% of the total energy consumption under various deployment densities. It extends a sensor network's functioning time in linear proportional to the deployed sensor population. Fan Ye received his B.E. in Automatic Control in 1996 and M.S. in Computer Science in 1999, both from Tsinghua University, Beijing, China. He received his Ph.D. in Computer Science in 2004 from UCLA. He is currently with IBM Research. His research interests are in wireless networks, sensor networks and security. Honghai Zhang received his BS in Computer Science in 1998 from University of Science and Technology of China. He received his MS and Ph.D. in Computer Science from University of Illinois at Urbana-Champaign. He is currently with the Wireless Advanced Technology Lab of Lucent Technologies. His research interests are wireless networks, WiMAX, and VoIP over wireless networks. Songwu Lu received both his M.S. and Ph.D. from University of Illinois at Urbana-Champaign. He is currently an associate professor at UCLA Computer Science. He received NSF CAREER award in 2001. His research interests include wireless networking, mobile computing, wireless security, and computer networks. Lixia Zhang received her Ph.D in computer science from the Massachusetts Institute of Technology. She was a member of the research staff at the Xerox Palo Alto Research Center before joining the faculty of UCLA’s Computer Science Department in 1995. In the past she has served on the Internet Architecture Board, Co-Chair of IEEE Communication Society Internet Technical Committee, the editorial board for the IEEE/ACM Transactions on Networking, and technical program committees for many networking-related conferences including SIGCOMM and INFOCOM. Zhang is currently serving as the vice chair of ACM SIGCOMM. Jennifer C. Hou received the Ph.D. degree in Electrical Engineering and Computer Science from The University of Michigan, Ann Arbor in 1993 and is currently a professor in the Department of Computer Science at University of Illinois at Urbana Champaign (UIUC). Prior to joining UIUC, she has taught at Ohio State University and University of Wisconsin - Madison. Dr. Hou has worked in the the areas of network modeling and simualtion, wireless-enabled software infrastructure for assisted living, and capacity optimization in wireless networks. She was a recipient of an ACM Recognition of Service, a Cisco University Research Award, a Lumley Research Award from Ohio State University, and a NSF CAREER award. ^*A Shorter version of this paper appeared in ICDCS 2003.     

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.     

A scalable, power-efficient broadcast algorithm for wireless networks

Scalability and power-efficiency are two of the most important design challenges in wireless ad hoc networks. In this paper, we present a scalable, power-efficient broadcast algorithm for wireless ad hoc networks. We first investigate the trade-off between (i) reaching more nodes in a single hop using higher transmission power and (ii) reaching fewer nodes using lower transmission power and relaying messages through multiple hops. Our analysis indicates that multi-hop broadcast is more power-efficient if α ≥ 2.2, where α is the path loss exponent in the power consumption model P(r,α) = c₀⋅ r^α+c₁. Based on the analysis, we then propose Broadcast over Local Spanning Subgraph (BLSS). In BLSS, an underlying topology is first constructed by a localized topology control algorithm, Fault-Tolerant Local Spanning Subgraph (FLSS). FLSS can preserve k-connectivity of the network, where the value of k determines the degree of fault tolerance. Broadcast messages are then simply relayed through the derived topology in a constrained flooding fashion. BLSS is fully localized, scalable, power-efficient, and fault-tolerant. Simulation results show that the performance of BLSS is comparable to that of centralized algorithms. Ning Li received the B.E. and M.E. degrees from Department of Automation, Tsinghua University, Beijing, PR China, in 1998 and 1999, respectively, and the M.S. degree in Computer Engineering from The Ohio State University, Columbus, OH, in 2001 and the Ph.D. degree in Computer Science from University of Illinois at Urbana-Champaign, Urbana, IL. His research interests include design and analysis of wireless mobile ad hoc networks and sensor networks, large-scale network simulation and emulation, and distributed and mobile computing. Jennifer C. Hou received her Ph.D. from The University of Michigan, Ann Arbor, MI in 1993. She is currently a professor in the Department of Computer Science at University of Illinois at Urbana-Champaign, Urbana, IL. Dr. Hou has been supervising several federally and industry funded projects in the areas of network modeling and simualtion, network measurement and diagnostics, enabling communication software for assisted living, and both the theoretical and protocol design aspects of wireless sensor networks. She has published (with her former advisor, students, and colleagues) over 125 papers and book chapters in archived journals and peer-reviewed conferences, and released a truly extensible, reusable, component-based, compositional network simulation and emulation package, J-Sim. She has also served on the TPC of several major networking, real-time, and distributed systems conferences/symposiums, such as IEEE INFOCOM, IEEE ICNP, IEEE ICDCS, IEEE RTSS, IEEE ICC, IEEE Globecome, ACM Mobicom, and ACM Sigmetrics. She is the Technical Program Co-chair of 27th IEEE INFOCOM 2008, First International Wireless Internet Conference 2005, ACM 3rd Information Processing in Sensor Networks (IPSN 2004) and IEEE Real-time Technology and Application Symposium (RTAS 2000). She is severing on the editorial board of IEEE Trans. on Wireless Communications, IEEE Trans. on Parallel and Distributed Systems, IEEE Wireless Communication Magazine, ACM/Kluwer Wireless Networks, Kluwer Computer Networks, and ACM Trans. on Sensor Networks. Dr. Hou was a recipient of an ACM Recognition of Service Award in 2004, a Lumley Research Award from The Ohio State University in 2001, a NSF CAREER award in 1996–2000 and a Women in Science Intiative Award from The University of Wisconsin—Madison in 1993–1995.     

A secure incentive protocol for mobile ad hoc networks

The proper functioning of mobile ad hoc networks depends on the hypothesis that each individual node is ready to forward packets for others. This common assumption, however, might be undermined by the existence of selfish users who are reluctant to act as packet relays in order to save their own resources. Such non-cooperative behavior would cause the sharp degradation of network throughput. To address this problem, we propose a credit-based Secure Incentive Protocol (SIP) to stimulate cooperation among mobile nodes with individual interests. SIP can be implemented in a fully distributed way and does not require any pre-deployed infrastructure. In addition, SIP is immune to a wide range of attacks and is of low communication overhead by using a Bloom filter. Detailed simulation studies have confirmed the efficacy and efficiency of SIP. This work was supported in part by the U.S. Office of Naval Research under Young Investigator Award N000140210464 and under grant N000140210554. Yanchao Zhang received the B.E. degree in Computer Communications from Nanjing University of Posts and Telecommunications, Nanjing, China, in July 1999, and the M.E. degree in Computer Applications from Beijing University of Posts and Telecommunications, Beijing, China, in April 2002. Since September 2002, he has been working towards the Ph.D. degree in the Department of Electrical and Computer Engineering at the University of Florida, Gainesville, Florida, USA. His research interests are network and distributed system security, wireless networking, and mobile computing, with emphasis on mobile ad hoc networks, wireless sensor networks, wireless mesh networks, and heterogeneous wired/wireless networks. Wenjing Lou is an assistant professor in the Electrical and Computer Engineering department at Worcester Polytechnic Institute. She obtained her Ph.D degree in Electrical and Computer Engineering from University of Florida in 2003. She received the M.A.Sc degree from Nanyang Technological University, Singapore, in 1998, the M.E degree and the B.E degree in Computer Science and Engineering from Xi'an Jiaotong University, China, in 1996 and 1993 respectively. From Dec 1997 to Jul 1999, she worked as a Research Engineer in Network Technology Research Center, Nanyang Technological University. Her current research interests are in the areas of ad hoc and sensor networks, with emphases on network security and routing issues. Wei Liu received his B.E. and M.E. in Electrical and Information Engineering from Huazhong University of Science and Technology, Wuhan, China, in 1998 and 2001. In August 2005, he received his PhD in Electrical and Computer Engineering from University of Florida. Currently, he is a senior technical member with Scalable Network Technologies. His research interest includes cross-layer design, and communication protocols for mobile ad hoc networks, wireless sensor networks and cellular networks. Yuguang Fang received a Ph.D. degree in Systems Engineering from Case Western Reserve University in January 1994 and a Ph.D degree in Electrical Engineering from Boston University in May 1997. He was an assistant professor in the Department of Electrical and Computer Engineering at New Jersey Institute of Technology from July 1998 to May 2000. He then joined the Department of Electrical and Computer Engineering at University of Florida in May 2000 as an assistant professor, got an early promotion to an associate professor with tenure in August 2003 and a professor in August 2005. He has published over 150 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 has served on many editorial boards of technical journals including IEEE Transactions on Communications, IEEE Transactions on Wireless Communications, IEEE Transactions on Mobile Computing and ACM Wireless Networks. He is a senior member of the IEEE.     

Multiconstrained QoS multipath routing in wireless sensor networks

Sensor nodes are densely deployed to accomplish various applications because of the inexpensive cost and small size. Depending on different applications, the traffic in the wireless sensor networks may be mixed with time-sensitive packets and reliability-demanding packets. Therefore, QoS routing is an important issue in wireless sensor networks. Our goal is to provide soft-QoS to different packets as path information is not readily available in wireless networks. In this paper, we utilize the multiple paths between the source and sink pairs for QoS provisioning. Unlike E2E QoS schemes, soft-QoS mapped into links on a path is provided based on local link state information. By the estimation and approximation of path quality, traditional NP-complete QoS problem can be transformed to a modest problem. The idea is to formulate the optimization problem as a probabilistic programming, then based on some approximation technique, we convert it into a deterministic linear programming, which is much easier and convenient to solve. More importantly, the resulting solution is also one to the original probabilistic programming. Simulation results demonstrate the effectiveness of our approach. This work was supported in part by the U.S. National Science Foundation under grant DBI-0529012, the National Science Foundation Faculty Early Career Development Award under grant ANI-0093241 and the Office of Naval Research under Young Investigator Award N000140210464. Xiaoxia Huang received her BS and MS in the Electrical Engineering from Huazhong University of Science and Technology in 2000 and 2002, respectively. She is completing her Ph.D. degree in the Department of Electrical and Computer Engineering at the University of Florida. Her research interests include mobile computing, QoS and routing in wireless ad hoc networks and wireless sensor networks. Yuguang Fang received a Ph.D. degree in Systems Engineering from Case Western Reserve University in January 1994 and a Ph.D degree in Electrical Engineering from Boston University in May 1997. He was an assistant professor in the Department of Electrical and Computer Engineering at New Jersey Institute of Technology from July 1998 to May 2000. He then joined the Department of Electrical and Computer Engineering at University of Florida in May 2000 as an assistant professor, got an early promotion to an associate professor with tenure in August 2003 and to a full professor in August 2005. He holds a University of Florida Research Foundation (UFRF) Professorship from 2006 to 2009. He has published over 200 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 has served on several editorial boards of technical journals including IEEE Transactions on Communications, IEEE Transactions on Wireless Communications, IEEE Transactions on Mobile Computing and ACM Wireless Networks. He have also been activitely participating in professional conference organizations such as serving as The Steering Committee Co-Chair for QShine, the Technical Program Vice-Chair for IEEE INFOCOM’2005, Technical Program Symposium Co-Chair for IEEE Globecom’2004, and a member of Technical Program Committee for IEEE INFOCOM (1998, 2000, 2003–2007).     

Algorithm design for a class of base station location problems in sensor networks

Base station placement has significant impact on sensor network performance. Despite its significance, results on this problem remain limited, particularly theoretical results that can provide performance guarantee. This paper proposes a set of procedure to design (1− ε) approximation algorithms for base station placement problems under any desired small error bound ε > 0. It offers a general framework to transform infinite search space to a finite-element search space with performance guarantee. We apply this procedure to solve two practical problems. In the first problem where the objective is to maximize network lifetime, an approximation algorithm designed through this procedure offers 1/ε² complexity reduction when compared to a state-of-the-art algorithm. This represents the best known result to this problem. In the second problem, we apply the design procedure to address base station placement problem when the optimization objective is to maximize network capacity. Our (1− ε) approximation algorithm is the first theoretical result on this problem. Yi Shi received his B.S. degree from University of Science and Technology of China, Hefei, China, in 1998, a M.S. degree from Institute of Software, Chinese Academy of Science, Beijing, China, in 2001, and a second M.S. degree from Virginia Tech, Blacksburg, VA, in 2003, all in computer science. He is currently working toward his Ph.D. degree in electrical and computer engineering at Virginia Tech. While in undergraduate, he was a recipient of Meritorious Award in International Mathematical Contest in Modeling and 1997 and 1998, respectively. His current research focuses on algorithms and optimizations for wireless sensor networks, wireless ad hoc networks, UWB-based networks, and SDR-based networks. His work has appeared in journals and highly selective international conferences (ACM Mobicom, ACM Mobihoc, and IEEE Infocom). Y. Thomas Hou received the B.E. degree from the City College of New York in 1991, the M.S. degree from Columbia University in 1993, and the Ph.D. degree from Polytechnic University, Brooklyn, New York, in 1998, all in Electrical Engineering. Since Fall 2002, he has been an Assistant Professor at Virginia Tech, the Bradley Department of Electrical and Computer Engineering, Blacksburg, VA. His current research interests are radio resource (spectrum) management and networking for software-defined radio wireless networks, optimization and algorithm design for wireless ad hoc and sensor networks, and video communications over dynamic ad hoc networks. From 1997 to 2002, Dr. Hou was a Researcher at Fujitsu Laboratories of America, Sunnyvale, CA, where he worked on scalable architectures, protocols, and implementations for differentiated services Internet, service overlay networking, video streaming, and network bandwidth allocation policies and distributed flow control algorithms. Prof. Hou is a recipient of an Office of Naval Research (ONR) Young Investigator Award (2003) and a National Science Foundation (NSF) CAREER Award (2004). He is a Co-Chair of Technical Program Committee of the Second International Conference on Cognitive Radio Oriented Wireless Networks and Communications (CROWNCOM 2007), Orlando, FL, August 1–3, 2007. He also was the Chair of the First IEEE Workshop on Networking Technologies for Software Defined Radio Networks, September 25, 2006, Reston, VA. Prof. Hou holds two U.S. patents and has three more pending. Alon Efrat earned his Bachelor in Applied Mathematics from the Technion (Israel’s Institute of Technology) in 1991, his Master in Computer Science from the Technion in 1993, and his Ph.D in Computer Science from Tel-Aviv University in 1998. During 1998–2000 he was a Post Doctorate Research Associate at the Computer Science Department of Stanford University, and at IBM Almaden Research Center. Since 2000, he is an assistant professor at the Computer Science Department of the University of Arizona. His main research areas are Computational Geometry, and its applications to sensor networks and medical imaging.     

Performance of a burst-frame-based CSMA/CA protocol: Analysis and enhancement

In this paper, we develop an analytical model to evaluate the delay performance of the burst-frame-based CSMA/CA protocol under unsaturated conditions, which has not been fully addressed in the literature. Our delay analysis is unique in that we consider the end-to-end packet delay, which is the duration from the epoch that a packet enters the queue at the MAC layer of the transmitter side to the epoch that the packet is successfully received at the receiver side. The analytical results give excellent agreement with the simulation results, which represents the accuracy of our analytical model. The results also provide important guideline on how to set the parameters of the burst assembly policy. Based on these results, we further develop an efficient adaptive burst assembly policy so as to optimize the throughput and delay performance of the burst-frame-based CSMA/CA protocol. Kejie Lu received the B.E. and M.E. degrees in Telecommunications Engineering from Beijing University of Posts and Telecommunications, Beijing, China, in 1994 and 1997, respectively. He received the Ph.D. degree in Electrical Engineering from the University of Texas at Dallas in 2003. In 2004 and 2005, he was a postdoctoral research associate in the Department of Electrical and Computer Engineering, University of Florida. Currently, he is an assistant professor in the Department of Electrical and Computer Engineering, University of Puerto Rico at Mayagüez. His research interests include architecture and protocols design for computer and communication networks, performance analysis, network security, and wireless communications. Jianfeng Wang received the B.E. and M.E. degrees in electrical engineering from Huazhong University of Science and Technology, China, in 1999 and 2002, respectively, and the Ph.D. degree in electrical engineering from University of Florida in 2006. From January 2006 to July 2006, he was a research intern in wireless standards and technology group, Intel Corporation. In October 2006, he joined Philips Research North America as a senior member research staff in wireless communications and networking department. He is engaged in research and standardization on wireless networks with emphasis on medium access control (MAC). Dapeng Wu received B.E. in Electrical Engineering from Huazhong University of Science and Technology, Wuhan, China, in 1990, M.E. in Electrical Engineering from Beijing University of Posts and Telecommunications, Beijing, China, in 1997, and Ph.D. in Electrical and Computer Engineering from Carnegie Mellon University, Pittsburgh, PA, in 2003. Since August 2003, he has been with Electrical and Computer Engineering Department at University of Florida, Gainesville, FL, as an Assistant Professor. His research interests are in the areas of networking, communications, multimedia, signal processing, and information and network security. He received the IEEE Circuits and Systems for Video Technology (CSVT) Transactions Best Paper Award for Year 2001, and the Best Paper Award in International Conference on Quality of Service in Heterogeneous Wired/Wireless Networks (QShine) 2006. Currently, he serves as the Editor-in-Chief of Journal of Advances in Multimedia, and an Associate Editor for IEEE Transactions on Wireless Communications, IEEE Transactions on Circuits and Systems for Video Technology, IEEE Transactions on Vehicular Technology, and International Journal of Ad Hoc and Ubiquitous Computing. He is also a guest-editor for IEEE Journal on Selected Areas in Communications (JSAC), Special Issue on Cross-layer Optimized Wireless Multimedia Communications. He served as Program Chair for IEEE/ACM First International Workshop on Broadband Wireless Services and Applications (BroadWISE 2004); and as a technical program committee member of over 30 conferences. He is Vice Chair of Mobile and wireless multimedia Interest Group (MobIG), Technical Committee on Multimedia Communications, IEEE Communications Society. He is a member of the Best Paper Award Committee, Technical Committee on Multimedia Communications, IEEE Communications Society. Yuguang Fang received a Ph.D. degree in Systems Engineering from Case Western Reserve University in January 1994 and a Ph.D. degree in Electrical Engineering from Boston University in May 1997. He was an assistant professor in the Department of Electrical and Computer Engineering at New Jersey Institute of Technology from July 1998 to May 2000. He then joined the Department of Electrical and Computer Engineering at University of Florida in May 2000 as an assistant professor and got an early promotion to an associate professor with tenure in August 2003 and to a full professor in August 2005. He has published over 200 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 has served on several editorial boards of technical journals including IEEE Transactions on Communications, IEEE Transactions on Wireless Communications, IEEE Transactions on Mobile Computing and ACM Wireless Networks. He have also been actively participating in professional conference organizations such as serving as The Steering Committee Co-Chair for QShine, the Technical Program Vice-Chair for IEEE INFOCOM’2005, Technical Program Symposium Co-Chair for IEEE Globecom’2004, and a member of Technical Program Committee for IEEE INFOCOM (1998, 2000, 2003–2007). He is a senior member of the IEEE.     

Power control for multicell CDMA wireless networks: A team optimization approach

We study power control in multicell CDMA wireless networks as a team optimization problem where each mobile attains at the minimum its individual fixed target SIR level and beyond that optimizes its transmission power level according to its individual preferences. We derive conditions under which the power control problem admits a unique feasible solution. Using a Lagrangian relaxation approach similar to [10] we obtain two decentralized dynamic power control algorithms: primal and dual power update, and establish their global stability utilizing both classical Lyapunov theory and the passivity framework [14]. We show that the robustness results of passivity studies [8, 9] as well as most of the stability and robustness analyses in the literature [10] are applicable to the power control problem considered. In addition, some of the basic principles of call admission control are investigated from the perspective of the model adopted in this paper. We illustrate the proposed power control schemes through simulations. Tansu Alpcan was with the University of Illinois at Urbana-Champaign during this research. X. Fan, M. Arcak, J. T. Wen: Research supported in part by the RPI Office of Research through an Exploratory Seed Grant. John Wen is supported by the China NSFC two-bases project under grant no. 60440420130. T. Başar: Research supported in part by the NSF Grant ITR 00-85917. Tansu Alpcan received the B.S. degree in electrical engineering from Bogazici University, Istanbul, Turkey in 1998. He received the M.S. and Ph.D. degrees in electrical and computer engineering from University of Illinois at Urbana-Champaign (UIUC) in 2001 and 2006, respectively. His research interests include game theory, control and optimization of wired and wireless communication networks, network security, and intrusion detection. He has received Fulbright scholarship in 1999 and best student paper award in IEEE Conference on Control Applications in 2003. He first authored more than 20 journal and conference articles and was an associate editor for IEEE Conference on Control Applications (CCA) in 2005. Tansu is the recipient of the Robert T. Chien Research Award from the UIUC Department of Electrical and Computer Engineering and Ross J. Martin Research Award from the UIUC College of Engineering in 2006. Tansu Alpcan is a (student) member of IEEE since 1998. Currently, he is a post-doctoral research scientist in Deutsche Telekom Laboratories, which is part of Technische Universitat Berlin, in Germany. Xingzhe Fan received the B.E. and M.E. degrees from Tsinghua University, Beijing, China, and the Ph.D. degree from the Electrical, Computer, and Systems Engineering Department, Rensselaer Polytechnic Institute, Troy, NY, in 1998, 2000, and 2004, respectively. He is currently a visiting assistant professor in Universifty of Miami, Miami, FL. His research interests are in nonlinear control and distributed optimization. Tamer Başar is with the University of Illinois at Urbana-Champaign (UIUC), where he holds the positions of the Fredric G. and Elizabeth H. Nearing Endowed Professor of Electrical and Computer Engineering, Center for Advanced Study Professor, and Research Professor at the Coordinated Science Laboratory. He received the B.S.E.E. degree from Robert College, Istanbul, in 1969, and the M.S., M.Phil, and Ph.D. degrees from Yale University during the period 1970–1972. He joined UIUC in 1981 after holding positions at Harvard University and Marmara Research Institute (Turkey). He has published extensively in systems, control, communications, and dynamic games, and has current research interests in modeling and control of communication networks; control over heterogeneous networks; resource allocation, management and pricing in networks; mobile computing; security issues in computer networks; and robust identification, estimation and control. Dr. Basar is the Editor-in-Chief of Automatica, Editor of the Birkhauser Series on Systems & Control, Editor of the Annals of the International Society of Dynamic Games (ISDG), and member of editorial and advisory boards of several international journals in control, wireless networks, and applied mathematics. He has received several awards and recognitions over the years, among which are the Medal of Science of Turkey (1993); Distinguished Member Award (1993), Axelby Outstanding Paper Award (1995), and Bode Lecture Prize (2004) of the IEEE Control Systems Society (CSS); Millennium Medal of IEEE (2000); Tau Beta Pi Drucker Eminent Faculty Award of UIUC (2004); the Outstanding Service Award (2005) and the Giorgio Quazza Medal (2005) of the International Federation of Automatic Control (IFAC); and the Richard E. Bellman Control Heritage Award of the American Automatic Control Council (2006). He is a member of the National Academy of Engineering (of USA), a member of the European Academy of Sciences, a Fellow of IEEE, a Fellow of IFAC, a past president of CSS, and the founding president of ISDG. Murat Arcak is an associate professor of Electrical, Computer and Systems Engineering at the Rensselaer Polytechnic Institute in Troy, NY. He was born in Istanbul, Turkey in 1973. He received the B.S. degree in Electrical and Electronics Engineering from the Bogazici University, Istanbul, in 1996, and the M.S. and Ph.D. degrees in Electrical and Computer Engineering from the University of California, Santa Barbara, in 1997 and 2000, under the direction of Petar Kokotovic. He joined Rensselaer in 2001. Dr. Arcak’s research is in nonlinear control theory and its applications, with particular interest in robust and observer-based feedback designs and in analysis and design of large-scale systems. In these areas he has published over eighty journal and conference papers, and organized several technical workshops. He is a member of SIAM, a senior member of IEEE, and an associate editor for the IFAC journal Automatica. He received a CAREER Award from the National Science Foundation in 2003, and the Donald P. Eckman Award from the American Automatic Control Council in 2006. John Ting-Yung Wen received B.Eng. from McGill University in 1979, M.S. from University of Illinois in 1981, and Ph.D. from Rensselaer Polytechnic Institute in 1985, all in Electrical Engineering. From 1981–1982, he was a system engineer at Fisher Controls where he developed a plant-wide coordination control system for pulp and paper plants. From 1985–1988, he was a member of technical staff at the Jet Propulsion Laboratory where he developed new modeling and control algorithms for large space structures and space robots. Since 1988, he has been with Rensselaer Polytechnic Institute where he is currently a professor in the Department of Electrical, Computer, and Systems Engineering with a joint appointment in the Department of Mechanical, Aerospace, and Nuclear Engineering. Since July 2005, he has been the Director of the Center for Automation Technologies and Systems, a multi-disciplinary research center supported by the New York State. Dr. Wen was an ASEE/NASA Summer Faculty Fellow in 1993, a Japan Society for the Promotion of Science (JSPS) Senior Visiting Scientist in 1997, and has received eleven NASA Tech Brief Awards. His research interest lies in the general area of modeling and control of high performance motion systems, model reduction for complex dynamical systems, and network based control including congestion regulation and multi-robot coordination. Dr. Wen is a Fellow of IEEE.     

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.     

Relay sensor placement in wireless sensor networks

This paper addresses the following relay sensor placement problem: given the set of duty sensors in the plane and the upper bound of the transmission range, compute the minimum number of relay sensors such that the induced topology by all sensors is globally connected. This problem is motivated by practically considering the tradeoff among performance, lifetime, and cost when designing sensor networks. In our study, this problem is modelled by a NP-hard network optimization problem named Steiner Minimum Tree with Minimum number of Steiner Points and bounded edge length (SMT-MSP). In this paper, we propose two approximate algorithms, and conduct detailed performance analysis. The first algorithm has a performance ratio of 3 and the second has a performance ratio of 2.5. Xiuzhen Cheng is an Assistant Professor in the Department of Computer Science at the George Washington University. She received her MS and PhD degrees in Computer Science from the University of Minnesota - Twin Cities in 2000 and 2002, respectively. Her current research interests include Wireless and Mobile Computing, Sensor Networks, Wireless Security, Statistical Pattern Recognition, Approximation Algorithm Design and Analysis, and Computational Medicine. She is an editor for the International Journal on Ad Hoc and Ubiquitous Computing and the International Journal of Sensor Networks. Dr. Cheng is a member of IEEE and ACM. She received the National Science Foundation CAREER Award in 2004. Ding-Zhu Du received his M.S. degree in 1982 from Institute of Applied Mathematics, Chinese Academy of Sciences, and his Ph.D. degree in 1985 from the University of California at Santa Barbara. He worked at Mathematical Sciences Research Institutea, Berkeley in 1985-86, at MIT in 1986-87, and at Princeton University in 1990-91. He was an associate-professor/professor at Department of Computer Science and Engineering, University of Minnesota in 1991-2005, a professor at City University of Hong Kong in 1998-1999, a research professor at Institute of Applied Mathematics, Chinese Academy of Sciences in 1987-2002, and a Program Director at National Science Foundation of USA in 2002-2005. Currently, he is a professor at Department of Computer Science, University of Texas at Dallas and the Dean of Science at Xi’an Jiaotong University. His research interests include design and analysis of algorithms for combinatorial optimization problems in communication networks and bioinformatics. He has published more than 140 journal papers and 10 written books. He is the editor-in-chief of Journal of Combinatorial Optimization and book series on Network Theory and Applications. He is also in editorial boards of more than 15 journals. Lusheng Wang received his PhD degree from McMaster University in 1995. He is an associate professor at City University of Hong Kong. His research interests include networks, algorithms and Bioinformatics. He is a member of IEEE and IEEE Computer Society. Baogang Xu received his PhD degree from Shandong University in 1997. He is a professor at Nanjing Normal University. His research interests include graph theory and algorithms on graphs.     

Strategyproof Mechanisms towards Dynamic Topology Formation in Autonomous Networks

In autonomous networks, cooperations among nodes cannot be assumed, since each node is capable of making independent decisions based on their personal preferences. In particular, when a node needs the help of intermediate nodes to relay messages to other nodes, these intermediaries may be reluctant to contribute their network resource for the benefit of others. Ideally, the right amount of incentives should be provided to motivate cooperations among autonomous nodes so that a mutually beneficial network results. In this paper, we leverage the power of mechanism design in microeconomics to design a distributed incentive mechanism that motivates each node towards a more desirable network topology. Since network parameters and constraints change dynamically in reality, the desirable topology can vary over time. Our solution presented in this paper has successfully encompassed such a dynamic nature of the network topology. In addition, we have transformed our solution to an easy-to-implement distributed algorithm, that converges towards the globally optimal topology. Selwyn Yuen obtained his BASc from the University of Waterloo Systems Design Engineering in 2002. He subsequently joined the Department of Electrical and Computer Engineering at the University of Toronto, where he completed his MASc in Computer Engineering in 2004. His Master thesis focuses on applying game theory and mechanism design in peer-to-peer and wireless networks. His other research interests include Artificial Intelligence, Optimization, Network Protocol Design, Distributed Algorithms, Operating Systems, as well as modelling and simulation of the Stock Market. Baochun Li received his B.Engr. degree in 1995 from Department of Computer Science and Technology, Tsinghua University, China, and his M.S. and Ph.D. degrees in 1997 and 2000 from the Department of Computer Science, University of Illinois at Urbana-Champaign. Since 2000, he has been with the Department of Electrical and Computer Engineering at the University of Toronto, where he is currently an Associate Professor and holds the Bell University Laboratories Endowed Chair in Computer Engineering. In 2000, he was the recipient of the IEEE Communications Society Leonard G. Abraham Award in the Field of Communications Systems. His research interests include application-level Quality of Service provisioning, wireless networks, and overlay networks.     

A Video Streaming System for Mobile Phones: Practice and Experience

This paper presents a case of video streaming system for mobile phone which has actually been implemented and deployed for commercial services in CDMA2000 1X cellular phone networks. As the computing environment and the network connection of cellular phones are significantly different from the wired desktop environment, the traditional desktop streaming method is not applicable. Therefore, a new architecture is required to suit the successfully streaming in the mobile phone environment. We have developed a very lightweight video player for use in mobile phone and the related authoring tool for the player. The streaming server has carefully been designed to provide high efficiency, reliability and scalability. Based on a specifically-designed suite of streaming protocol, the server employs an adaptive rate control mechanism which transmits the media packets appropriately into the network according to the change in network bandwidth.Hojung Cha is currently a professor in computer science at Yonsei University, Seoul, Korea. His research interests include multimedia computing system, multimedia communication networks, wireless and mobile communication systems and embedded system software. He received his B.S. and M.S. in computer engineering from Seoul National University, Korea, in 1985 and 1987, respectively. He received his Ph.D. in computer science from the University of Manchester, England, in 1991.Jongmin Lee is a Ph.D. candidiate in computer science at Yonsei University, Seoul, Korea. His research interests include wireless multimedia system, QoS architecture, multimedia communication networks. He received his B.S. and M.S. in computer science from Kwangwoon University in 1999 and 2001, respectively.Jongho Nang is a professor in the Department of Computer Science at Sogang University. He received his B.S. degree from Sogang University, Korea, in 1986 and M.S. and Ph.D. degree from KAIST, in 1988 and in 1992, respectively. His research interests are in the field of multimedia systems, digital video library, and Internet technologies. He is a member of KISS, ACM, and IEEE.Sung-Yong Park is an associate professor in the Department of Computer Science at Sogang University, Seoul, Korea. He received his B.S. degree in computer science from Sogang University, and both the M.S. and Ph.D. degrees in computer science from Syracuse University. From 1987 to 1992, he worked for LG Electronics, Korea, as a research engineer. From 1998 to 1999, he was a research scientist at Telcordia Technologies (formerly Bellcore) where he developed network management software for optical switches. His research interests include high performance distributed computing and systems, operating systems, and multimedia.Jin-Hwan Jeong received the B.S. and M.S. degrees in computer science from Korea University, Seoul, Korea, in 1997, and 1999, respectively. He is currently in Ph.D. course at Korea University. His research interests include video processing for thin devices, multimedia streaming and operating systems.Chuck Yoo received the B.S. degree in electronics engineering from Seoul National University, Seoul, Korea and the M.S. and Ph.D. in computer science in University of Michigan. He worked as a researcher in Sun Microsystems Lab. from 1990 to 1995. He joined the Computer Science and Enginnering Department, Korea University, Seoul, Korea in 1995, where he is currently a professor. His research interests include high performance network, multimedia streaming, and operating systems.Jin-Young Choi received the B.S. degree from Seoul National University, Seoul, Korea, in 1982, the M.S. degree from Drexel University in 1986, and the Ph.D. degree from University of Pennsylvania, in 1993. He is currently a professor of Computer Science and Engineering Department, Korea University, Seoul, Korea. His current research interests are in real-time computing, formal methods, programming languages, process algebras, security, software engineering, and protocol engineering.     

Probabilistic Power Management for Wireless Ad Hoc Networks

Extending system lifetime by effectively managing power on participating nodes is critical in wireless ad hoc networks. Recent work has shown that, by appropriately powering off nodes, energy may be significantly saved up to a factor of two, especially when node density is high. Such approaches rely on the selection of a virtual backbone (i.e., a connected dominating set) of the topology to forward ongoing traffic, coupled with algorithms to manually and periodically recompute such a backbone for load balancing purposes. The common drawback of such schemes is the need to involve periodic message exchanges and to make additional restrictive assumptions. This paper presents Odds¹, an integrated set of energy-efficient and fully distributed algorithms for power management in wireless ad hoc networks. Odds build on the observation that explicit and periodic re-computation of the backbone topology is costly with respect to its additional bandwidth overhead, especially when nodes are densely populated or highly mobile. Building on a fully probabilistic approach, Odds seek to make a minimum overhead, perfectly balanced, and fully localized decision on each node with respect to when and how long it needs to enter standby mode to conserve energy. Such a decision does not rely on periodic message broadcasts in the local neighborhood, so that Odds are scalable as node density increases. Detailed mathematical analysis, discussions and simulation results have shown that Odds are indeed able to achieve our objectives while operating in a wide range of density and traffic loads.Zongpeng Li received his B.Engr. in 1999, from Department of Computer Science and Technology, Tsinghua University, China, and his M.S. degree in 2001 from the Department of Computer Science, University of Toronto. He is currently working towards his Ph.D. degree in the Department of Electrical and Computer Engineering, University of Toronto. His research interests include algorithm design and analysis for both wireless and wireline networks.Baochun Li received his B.Engr. degree in 1995 from Department of Computer Science and Technology, Tsinghua University, China, and his M.S. and Ph.D. degrees in 1997 and 2000 from the Department of Computer Science, University of Illinois at Urbana-Champaign. Since 2000, he has been with the Department of Electrical and Computer Engineering at the University of Toronto, where he is an Assistant Professor. In 2000, he was the recipient of the IEEE Communications Society Leonard G. Abraham Award in the Field of Communications Systems. His research interests include network-level and application-level Quality of Service provisioning, application-layer overlay networks, wireless ad hoc networks, and mobile computing.     

Maximizing Network Lifetime of Broadcasting Over Wireless Stationary Ad Hoc Networks

We investigate the problem of extending the network lifetime of a single broadcast session over wireless stationary ad hoc networks where the hosts are not mobile. We define the network lifetime as the time from network initialization to the first node failure due to battery depletion. We provide through graph theoretic approaches a polynomial-time globally optimal solution, a variant of the minimum spanning tree (MST), to the problem of maximizing the static network lifetime. We make use of this solution to develop a periodic tree update strategy for effective load balancing and show that a significant gain in network lifetime over the optimal static network lifetime can be achieved. We provide extensive comparative simulation studies on parameters such as update interval and control overhead and investigate their impact on the network lifetime. The simulation results are also compared with an upper bound to the network lifetime. A preliminary version of this paper appeared in IEEE ICC 2003 [35]. This research was funded in part by NSF grant ANI-0093187, ONR award #: N00014-04-1-0479 and Collaborative Technology Alliance (CTA) from ARL under DAAD19-01-2-0011. All statements and opinions are that of the authors and do not represent any position of the U.S government Intae Kang received his B.S. degree in physics from Seoul National University, Seoul, Korea and M.S. degree in electrical engineering from the Johns Hopkins University, Baltimore, MD. He is currently working toward the Ph.D. degree in the Department of Electrical Engineering at the University of Washington, Seattle, WA. His current research interests are in the area of ad hoc and sensor networks. In particular, he is interested in energy efficient routing, topology control, medium access control, mobility management, and modeling and performance analysis of network protocols using directional/smart antennas. Radha Poovendran has been an assistant professor at the Electrical Engineering Department of the University of Washington at Seattle since September 2000. He received his Ph.D. in Electrical Engineering from the University of Maryland, College Park in 1999. His research interests are in the areas of applied cryptography for multiuser environment, wireless networking, and applications of Information Theory to security. He is a recipient of Faculty Early Career Award from the National Science Foundation (2001), Young Investigator Award from the Army Research Office (2002), Young Investigator Award from the Office of Naval Research (2004), and the 2004 Presidential Early Career Award for Scientists and Engineers, for his research contributions in the areas of wired and wireless multiuser security. He is also a co-recipient of the 2002 Outstanding Teaching as well as the Outstanding Advisor Awards from the Department of Electrical Engineering of the University of Washington.     

Cross-layer optimization for end-to-end rate allocation in multi-radio wireless mesh networks

In this paper, we study rate allocation for a set of end-to-end communication sessions in multi-radio wireless mesh networks. We propose cross-layer schemes to solve the joint rate allocation, routing, scheduling, power control and channel assignment problems with the goals of maximizing network throughput and achieving certain fairness. Fairness is addressed using both a simplified max-min fairness model and the well-known proportional fairness model. Our schemes can also offer performance upper bounds such as an upper bound on the maximum throughput. Numerical results show that our proportional fair rate allocation scheme achieves a good tradeoff between throughput and fairness. Jian Tang is an assistant professor in the Department of Computer Science at Montana State University. He received the Ph.D. degree in Computer Science from Arizona State University in 2006. His research interest is in the area of wireless networking and mobile computing. He has served on the technical program committees of multiple international conferences, including ICC, Globecom, IPCCC and QShine. He will also serve as a publicity co-chair of International Conference on Autonomic Computing and Communication Systems (Autonomics’2007). Guoliang Xue is a Full Professor in the Department of Computer Science and Engineering at Arizona State University. He received the Ph.D. degree in Computer Science from the University of Minnesota in 1991 and has held previous positions at the Army High Performance Computing Research Center and the University of Vermont. His research interests include efficient algorithms for optimization problems in networking, with applications to fault tolerance, robustness, and privacy issues in networks ranging from WDM optical networks to wireless ad hoc and sensor networks. He has published over 150 papers in these areas. His research has been continuously supported by federal agencies including NSF and ARO. He is the recipient of an NSF Research Initiation Award in 1994 and an NSF-ITR Award in 2003. He is an Associate Editor of Computer Networks (COMNET), the IEEE Network Magazine, and Journal of Global Optimization. He has served on the executive/program committees of many IEEE conferences, including INFOCOM, SECON, IWQOS, ICC, GLOBECOM and QShine. He is the General Chair of IEEE IPCCC’2005, a TPC co-Chair of IPCCC’2003, HPSR’2004, IEEE Globecom’2006 Symposium on Wireless Ad Hoc and Sensor Networks, IEEE ICC’2007 Symposium on Wireless Ad Hoc and Sensor Networks, and QShine’2007. He is a senior member of IEEE. Weiyi Zhang received the M.E. degree in 1999 from Southeast University, China. Currently he is a Ph.D. student in the Department of Computer Science and Engineering at Arizona State University. His research interests include reliable communication in networking, protection and restoration in WDM networks, and QoS provisioning in communication networks.     

Improving Wireless Sensor Network Lifetime through Power Aware Organization

A critical aspect of applications with wireless sensor networks is network lifetime. Battery-powered sensors are usable as long as they can communicate captured data to a processing node. Sensing and communications consume energy, therefore judicious power management and scheduling can effectively extend operational time. To monitor a set of targets with known locations when ground access in the monitored area is prohibited, one solution is to deploy the sensors remotely, from an aircraft. The loss of precise sensor placement would then be compensated by a large sensor population density in the drop zone, that would improve the probability of target coverage. The data collected from the sensors is sent to a central node for processing. In this paper we propose an efficient method to extend the sensor network operational time by organizing the sensors into a maximal number of disjoint set covers that are activated successively. Only the sensors from the current active set are responsible for monitoring all targets and for transmitting the collected data, while nodes from all other sets are in a low-energy sleep mode. In this paper we address the maximum disjoint set covers problem and we design a heuristic that computes the sets. Theoretical analysis and performance evaluation results are presented to verify our approach.Mihaela Cardei is an Assistant Professor in the Department of Computer Science and Engineering at the Florida Atlantic University. Her research interests are in the areas of wireless networking, wireless sensor networks, algorithm and protocol design in communication networks and resource management. Mihaela Cardei received her M.S. and Ph.D. in Computer Science from the University of Minnesota in 1999 and 2003 respectively. Her Ph.D. adviser was Dr. Ding-Zhu Du. During her graduate studies, she worked with Honeywell Laboratories on the Real Time Adaptive Resource Management DARPA project. She is also a recipient of the University of Minnesota Graduate School Doctoral Dissertation Fellowship for 2002–2003.Ding-Zhu Du received his M.S. degree in 1982 from Institute of Applied Mathematics, Chinese Academy of Sciences under the supervision of Minyi Yue, and his Ph.D. degree in 1985 from the University of California at Santa Barbara under the supervision of Ronald V. Book. He worked at Mathematical Sciences Research Institute, Berkeley in 1985–86, at MIT in 1986–87, and at Princeton University in 1990–91. Currently, he is a professor at Department of Computer Science, University of Minnesota and also a research professor at Institute of Applied Mathematics, Chinese Academy of Sciences. His research interests include combinatorial optimization, communication networks, and theory of computation. He has published more than 140 journal papers and 30 books. Currently, he is the editor-in-chief of Journal of Combinatorial Optimization and book series on Network Theory and Applications. He is also in editorial boards of eight journals.     

On-demand diversity wireless relay networks

There has been much recent attention on using wireless relay networks to forward data from mobile nodes to a base station. This network architecture is motivated by performance improvements obtained by leveraging the highest quality links to a base station for data transfer. With the advent of agile radios it is possible to improve the performance of relay networks through intelligent frequency assignments. First, it is beneficial if the links of the relay network are orthogonal with respect to each other so that simultaneous transmission on all links is possible. Second, diversity can be added to hops in the relay network to reduce error rates. In this paper we present algorithms for forming such relay networks dynamically. The formation algorithms support intelligent frequency assignments and diversity setup. Our results show that algorithms that order the sequence in which nodes join a relay network carefully, achieve the highest amount of diversity and hence best performance. This research is supported in part by NSF grant CNS-0508114. JaeSheung Shin received the B.S. and M.S. degree in Computer Science and Engineering from DongGuk University, Korea, in 1991 and 1993, respectively. He is currently working toward the Ph.D. degree in Computer Science and Engineering at the Pennsylvania State University, University Park. He is a research assistant at the Networking and Security Research Center (NSRC). Prior to joining Pennsylvania State University, he was with Electronics and Telecommunications Research Institute (ETRI), Korea, since 1993. He worked on development of 2G and 3G wireless cellular core network elements. His research interests include mobility management and signaling for wireless cellular and routing and resource allocation for multi-radio multi-hop wireless cellular networks. Kyounghwan Lee received the B.S. degree in Electrical and Electronics Engineering from University of Seoul, Seoul, Korea, in 2000, and the M.S. degree in Information and Communication Engineering from Gwangju Institute of Science and Technology, Gwangju, Korea, in 2002. He is currently a Ph.D candidate at the Electrical Engineering department at the Pennsylvania State University and a research assistant at the Wireless Communications and Networking Laboratory (WCAN@PSU). His research interests include wireless communication theory and relay networks. E-mail: kxl251@psu.edu Aylin Yener received the B.S. degrees in Electrical and Electronics Engineering, and in Physics, from Bogazici University, Istanbul, Turkey, in 1991, and the M.S. and Ph.D. degrees in Electrical and Computer Engineering from Rutgers University, NJ, in 1994 and 2000, respectively. During her Ph.D. studies, she was with Wireless Information Network Laboratory (WINLAB) in the Department of Electrical and Computer Engineering at Rutgers University, NJ. Between fall 2000 and fall 2001, she was with the Electrical Engineering and Computer Science Department at Lehigh University, PA, where she was a P.C. Rossin assistant professor. Currently, she is with the Electrical Engineering department at the Pennsylvania State University, University Park, PA, as an assistant professor. Dr. Yener is a recipient of the NSF CAREER award in 2003. She is an associate editor of the IEEE Transactions on Wireless Communications. Dr. Yener’s research interests include performance enhancement of multiuser systems, wireless communication theory and wireless networking. Thomas F. La Porta received his B.S.E.E. and M.S.E.E. degrees from The Cooper Union, New York, NY, and his Ph.D. degree in Electrical Engineering from Columbia University, New York, NY. He joined the Computer Science and Engineering Department at Penn State in 2002 as a Full Professor. He is the Director of the Networking Research Center at Penn State. Prior to joining Penn State, Dr. La Porta was with Bell Laboratories since 1986. He was the Director of the Mobile Networking Research Department in Bell Laboratories, Lucent Technologies. He is an IEEE Fellow and Bell Labs Fellow. Dr. La Porta was the founding Editor-in-Chief of the IEEE Transactions on Mobile Computing. He has published over 50 technical papers and holds 25 patents.     

An unequal cluster-based routing protocol in wireless sensor networks

Clustering provides an effective method for prolonging the lifetime of a wireless sensor network. Current clustering algorithms usually utilize two techniques; selecting cluster heads with more residual energy, and rotating cluster heads periodically to distribute the energy consumption among nodes in each cluster and extend the network lifetime. However, they rarely consider the hot spot problem in multihop sensor networks. When cluster heads cooperate with each other to forward their data to the base station, the cluster heads closer to the base station are burdened with heavier relay traffic and tend to die much faster, leaving areas of the network uncovered and causing network partitions. To mitigate the hot spot problem, we propose an Unequal Cluster-based Routing (UCR) protocol. It groups the nodes into clusters of unequal sizes. Cluster heads closer to the base station have smaller cluster sizes than those farther from the base station, thus they can preserve some energy for the inter-cluster data forwarding. A greedy geographic and energy-aware routing protocol is designed for the inter-cluster communication, which considers the tradeoff between the energy cost of relay paths and the residual energy of relay nodes. Simulation results show that UCR mitigates the hot spot problem and achieves an obvious improvement on the network lifetime. Guihai Chen obtained his B.S. degree from Nanjing University, M. Engineering from Southeast University, and PhD from University of Hong Kong. He visited Kyushu Institute of Technology, Japan in 1998 as a research fellow, and University of Queensland, Australia in 2000 as a visiting professor. During September 2001 to August 2003, he was a visiting professor at Wayne State University. He is now a full professor and deputy chair of Department of Computer Science, Nanjing University. Prof. Chen has published more than 100 papers in peer-reviewed journals and refereed conference proceedings in the areas of wireless sensor networks, high-performance computer architecture, peer-to-peer computing and performance evaluation. He has also served on technical program committees of numerous international conferences. He is a member of the IEEE Computer Society. Chengfa Li was born 1981 and obtained his Bachelor’s Degree in mathematics in 2003 and his Masters Degree in computer science in 2006, both from Nanjing University, China. He is now a system programmer at Lucent Technologies Nanjing Telecommunication Corporation. His research interests include wireless ad hoc and sensor networks. Mao Ye was born in 1981 and obtained his Bachelor’s Degree in computer science from Nanjing University, China, in 2004. He served as a research assistant At City University of Hong Kong from September 2005 to August 2006. He is now a PhD candidate with research interests in wireless networks, mobile computing, and distributed systems. Jie Wu is a professor in the Department of Computer Science and Engineering at Florida Atlantic University. He has published more than 300 papers in various journal and conference proceedings. His research interests are in the areas of mobile computing, routing protocols, fault-tolerant computing, and interconnection networks. Dr. Wu serves as an associate editor for the IEEE Transactions on Parallel and Distributed Systems and several other international journals. He served as an IEEE Computer Society Distinguished Visitor and is currently the chair of the IEEE Technical Committee on Distributed Processing (TCDP). He is a member of the ACM, a senior member of the IEEE, and a member of the IEEE Computer Society.     

Localized algorithms for coverage boundary detection in wireless sensor networks

Connected coverage, which reflects how well a target field is monitored under the base station, is the most important performance metric used to measure the quality of surveillance that wireless sensor networks (WSNs) can provide. To facilitate the measurement of this metric, we propose two novel algorithms for individual sensor nodes to identify whether they are on the coverage boundary, i.e., the boundary of a coverage hole or network partition. Our algorithms are based on two novel computational geometric techniques called localized Voronoi and neighbor embracing polygons. Compared to previous work, our algorithms can be applied to WSNs of arbitrary topologies. The algorithms are fully distributed in the sense that only the minimal position information of one-hop neighbors and a limited number of simple local computations are needed, and thus are of high scalability and energy efficiency. We show the correctness and efficiency of our algorithms by theoretical proofs and extensive simulations. Chi Zhang received the B.E. and M.E. degrees in Electrical Engineering from Huazhong University of Science and Technology, Wuhan, China, in July 1999 and January 2002, respectively. Since September 2004, he has been working towards the Ph.D. degree in the Department of Electrical and Computer Engineering at the University of Florida, Gainesville, Florida, USA. His research interests are network and distributed system security, wireless networking, and mobile computing, with emphasis on mobile ad hoc networks, wireless sensor networks, wireless mesh networks, and heterogeneous wired/wireless networks. Yanchao Zhang received the B.E. degree in computer communications from Nanjing University of Posts and Telecommunications, Nanjing, China, in July 1999, the M.E. degree in computer applications from Beijing University of Posts and Telecommunications, Beijing, China, in April 2002, and the Ph.D. degree in electrical and computer engineering from the University of Florida, Gainesville, in August 2006. Since September 2006, he has been an Assistant Professor in the Department of Electrical and Computer Engineering, New Jersey Institute of Technology, Newark. His research interest include wireless and Internet security, wireless networking, and mobile computing. He is a member of the IEEE and ACM. Yuguang Fang received the BS and MS degrees in Mathematics from Qufu Normal University, Qufu, Shandong, China, in 1984 and 1987, respectively, a Ph.D. degree in Systems and Control Engineering from Department of Systems, Control and Industrial Engineering at Case Western Reserve University, Cleveland, Ohio, in January 1994, and a Ph.D. degree in Electrical Engineering from Department of Electrical and Computer Engineering at Boston University, Massachusetts, in May 1997. From 1987 to 1988, he held research and teaching position in both Department of Mathematics and the Institute of Automation at Qufu Normal University. From September 1989 to December 1993, he was a teaching/research assistant in Department of Systems, Control and Industrial Engineering at Case Western Reserve University, where he held a research associate position from January 1994 to May 1994. He held a post-doctoral position in Department of Electrical and Computer Engineering at Boston University from June 1994 to August 1995. From September 1995 to May 1997, he was a research assistant in Department of Electrical and Computer Engineering at Boston University. 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, Newark, New Jersey. In May 2000, he joined the Department of Electrical and Computer Engineering at University of Florida, Gainesville, Florida, where he got early promotion to Associate Professor with tenure in August 2003, and to Full Professor in August 2005. His research interests span many areas including wireless networks, mobile computing, mobile communications, wireless security, automatic control, and neural networks. He has published over one hundred and fifty (150) 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 also received the 2001 CAST Academic Award. He is listed in Marquis Who’s Who in Science and Engineering, Who’s Who in America and Who’s Who in World. Dr. Fang has actively engaged in many professional activities. He is a senior member of the IEEE and a member of the ACM. He is an Editor for IEEE Transactions on Communications, an Editor for IEEE Transactions on Wireless Communications, an Editor for IEEE Transactions on Mobile Computing, an Editor for ACM Wireless Networks, and an Editor for IEEE Wireless Communications. He was an Editor for IEEE Journal on Selected Areas in Communications:Wireless Communications Series, an Area Editor for ACM Mobile Computing and Communications Review, an Editor for Wiley International Journal on Wireless Communications and Mobile Computing, and Feature Editor for Scanning the Literature in IEEE Personal Communications. He has also actively involved with many professional conferences such as ACM MobiCom’02 (Committee Co-Chair for Student Travel Award), MobiCom’01, IEEE INFOCOM’06, INFOCOM’05 (Vice-Chair for Technical Program Committee), INFOCOM’04, INFOCOM’03, INFOCOM’00, INFOCOM’98, IEEE WCNC’04, WCNC’02, WCNC’00 Technical Program Vice-Chair), WCNC’99, IEEE Globecom’04 (Symposium Co-Chair), Globecom’02, and International Conference on Computer Communications and Networking (IC3N) (Technical Program Vice-Chair).     

MANTIS OS: An Embedded Multithreaded Operating System for Wireless Micro Sensor Platforms

The MANTIS MultimodAl system for NeTworks of In-situ wireless Sensors provides a new multithreaded cross-platform embedded operating system for wireless sensor networks. As sensor networks accommodate increasingly complex tasks such as compression/aggregation and signal processing, preemptive multithreading in the MANTIS sensor OS (MOS) enables micro sensor nodes to natively interleave complex tasks with time-sensitive tasks, thereby mitigating the bounded buffer producer-consumer problem. To achieve memory efficiency, MOS is implemented in a lightweight RAM footprint that fits in less than 500 bytes of memory, including kernel, scheduler, and network stack. To achieve energy efficiency, the MOS power-efficient scheduler sleeps the microcontroller after all active threads have called the MOS sleep() function, reducing current consumption to the μA range. A key MOS design feature is flexibility in the form of cross-platform support and testing across PCs, PDAs, and different micro sensor platforms. Another key MOS design feature is support for remote management of in-situ sensors via dynamic reprogramming and remote login. Shah Bhatti is a Ph.D. student in Computer Science at the University of Colorado at Boulder. He also works as a Senior Program Manager in the R&D Lab for Imaging and Printing Group (IPG) at Hewlett Packard in Boise, Idaho. He has participated as a panelist in workshops on Integrated Architecture for Manufacturing and Component-Based Software Engineering, at IJCAI ‘89 and ICSE ‘98, respectively. Hewlett Packard has filed several patents on his behalf. He received an MSCS and an MBA from the University of Colorado, an MSCE from NTU and a BSCS from Wichita State University. His research interests include power management, operating system design and efficient models for wireless sensor networks. James Carlson is a Ph.D. student in Computer Science at the University of Colorado at Boulder. He received his Bachelor’s degree from Hampshire College in 1997. His research is supported by the BP Visualization Center at CU-Boulder. His research interests include computer graphics, 3D visualization, and sensor-enabled computer-human user interfaces. Hui Dai is a Ph.D. student in Computer Science at the University of Colorado at Boulder. He received his B.E. from the University of Science and Technology, China in 2000, and received has M.S. in Computer Science from the University of Colorado at Boulder in 2002. He has been co-leading the development of the MANTIS OS. His research interests include system design for wireless sensor networks, time synchronization, distributed systems and mobile computing. Jing Deng is a Ph.D. student in Computer Science at the University of Colorado at Boulder. He received his B.E. from Univeristy of Electronic Science and Technology of China in 1993, and his M.E from Institute of Computing Technology, Chinese Academy of Science in 1996. He has published four papers on security wireless sensor networks and is preparing a book chapter on security, privacy, and fault tolerance in sensor networks. His research interests include wireless security, secure network routing, and security for sensor networks. Jeff Rose is an M.S. student in Computer Science at the University of Colorado at Boulder. He received his B.S. in Computer Science from the University of Colorado at Boulder in 2003. He has been co-leading the development of the MANTIS operating system. His research interests include data-driven routing in sensor networks. Anmol Sheth is a Ph.D. student in Computer Science at the University of Colorado at Boulder. He received his B.S. in Computer Science from the University of Pune, India in 2001. His research interests include MAC layer protocol design, energy-efficient wireless communication, and adapting communications to mobility. Brian Shucker is a Ph.D. student in Computer Science at the University of Colorado at Boulder. He received his B.S. in Computer Science from the University of Arizona in 2001, and his M.S. in Computer Science from the University of Colorado at Boulder in December 2003. He has been co-leading the development of the MANTIS operating system. His research interests in wireless sensor networks include operating systems design, communication networking, and robotic sensor networks. Charles Gruenwald is an undergraduate student in Computer Science at the University of Colorado at Boulder. He joined the MANTIS research group in Fall 2003 as an undergraduate researcher. Adam Torgerson is an undergraduate student in Computer Science at the University of Colorado at Boulder. He joined the MANTIS research group in Fall 2003 as an undergraduate researcher. Richard Han joined the Department of Computer Science at the University of Colorado at Boulder in August 2001 as an Assistant Professor, Prof. Han leads the MANTIS wireless sensor networking research project, http://mantis.cs.colorado.edu. He has served on numerous technical program committees for conferences and workshops in the field of wireless sensor networks. He received a National Science Foundation CAREER Award in 2002 and IBM Faculty Awards in 2002 and 2003. He was a Research Staff Member at IBM’s Thomas J. Watson Research Center in Hawthorne, New York from 1997-2001. He received his Ph.D. in Electrical Engineering from the University of California at Berkeley in 1997, and his B.S. in Electrical Engineering with distinction from Stanford University in 1989. His research interests include systems design for sensor networks, secure wireless sensor networks, wireless networking, and sensor-enabled user interfaces.This revised version was published online in August 2005 with a corrected cover date.