Radio Resource Management with Utility and Pricing for Wireless LAN Hot-Spots

We investigate Wireless LAN hot-spots based on the IEEE 802.11b protocol, considering technical and economic issues of the Radio Resource Allocation. Firstly, we discuss how to model the trade-off between perceived QoS and paid price in the users' request, so as to represent the users as choosing the most satisfactory allocation, determined by service requirements and willingness to pay. After the setup of the users' requests, the multiple medium access mechanism is considered and the network performance is evaluated and discussed. Thus, we investigate the provider's task of having a suitable price policy which gives a satisfactory income and efficiently exploit network capacity. This is also dependent on a price setting that is accepted by the users and optimises resource usage. Finally, we study how the multiple access scheme specified in the IEEE 802.11b protocol combines users' requests to a final allocation, and identify possibilities of improvement for the inherent inefficiencies arising from overload. Leonardo Badia was born in Ferrara, Italy, in 1977. He received the MS Degree in Electrical Engineering and the PhD in Information Engineering both from the University of Ferrara, Italy, in 2000 and 2004 respectively. In 2001 he joined the Department of Engineering of the University of Ferrara, where he is a currently a post-doc researcher. During 2002 and 2003 he was on leave at the Royal Institute of Technology of Stockholm, Sweden. His research interests include energy efficient Ad Hoc Networks, transmission protocol modelling, Admission Control and economic modelling of Radio Resource Management for Wireless Networks. Michele Zorzi was born in Venice, Italy, in 1966. He received the Laurea Degree and the Ph.D. in Electrical Engineering from the University of Padova, Italy, in 1990 and 1994, respectively. During the Academic Year 1992/93, he was on leave as a graduate student at the University of California, San Diego (UCSD), where he did research on multiple access in mobile radio networks. In 1993, he joined the faculty of the Dipartimento di Elettronica e Informazione, Politecnico di Milano, Italy. After spending three years with the Center for Wireless Communications at UCSD, in 1998 he joined the School of Engineering of the University di Ferrara, Italy. Since November 2003, he has been on the faculty at the Information Engineering Department of the University of Padova. His present research interests include performance evaluation in mobile communications systems, random access in mobile radio networks, ad hoc and sensor networks, and energy constrained communications protocols. Dr. Zorzi is the Editor-In-Chief of the IEEE Wireless Communications Magazine, and currently serves on the Editorial Boards of the IEEE Transactions on Communications, the IEEE Transactions on Wireless Communications, the IEEE Transactions on Mobile Computing, the Wiley Journal of Wireless Communications and Mobile Computing and the ACM/URSI/ Kluwer Journal of Wireless Networks.     

Dynamic utility and price based radio resource management for rate adaptive traffic

This paper explores analytical Radio Resource Management models where the relationship between users and services is mapped through utility functions. Compared to other applications of these models to networking, we focus in particular on specific aspects of multimedia systems with adaptive traffic, and propose a novel framework for describing and investigating dynamic allocation of resources in wireless networks. In doing so, we also consider economic aspects, such as the financial needs of the provider and the users’ reaction to prices. As an example of how our analytical tool can be used, in this paper we compare different classes of RRM strategies, e.g., Best Effort vs. Guaranteed Performance, for which we explore the relationships between Radio Resource Allocation, pricing, provider’s revenue, network capacity and users’ satisfaction. Finally, we present a discussion about Economic Admission Control, which can be applied in Best Effort scenarios to further improve the performance. Part of this work has been presented at the conference ACM/IEEE MSWiM 2004, Venice (Italy). Leonardo Badia received a Laurea degree (with honors) in electrical engineering and a Ph.D. in information engineering from the University of Ferrara, Italy, in 2000 and 2004, respectively. He was a Research Fellow at the University of Ferrara from 2001 to 2006. During these years, he also had collaborations with the University of Padova, Italy, and Wireless@KTH, Royal Institute of Technology, Stockholm, Sweden. In 2006, he joined the “Institutions Markets Technologies” (IMT) Institute for Advanced Studies, Lucca, Italy, where he is currently a Research Fellow. His research interests include wireless ad hoc and mesh networks, analysis of transmission protocols, optimization tools and economic models applied to radio resource management. Michele Zorzi received a Laurea degree and a Ph.D. in electrical engineering from the University of Padova in 1990 and 1994, respectively. During academic year 1992–1993, he was on leave at UCSD, attending graduate courses and doing research on multiple access in mobile radio networks. In 1993 he joined the faculty of the Dipartimento di Elettronica e Informazione, Politecnico di Milano, Italy. After spending three years with the Center for Wireless Communications at UCSD, in 1998 he joined the School of Engineering of the University of Ferrara, Italy, where he became a professor in 2000. Since November 2003 he has been on the faculty at the Information Engineering Department of the University of Padova. His present research interests include performance evaluation in mobile communications systems, random access in mobile radio networks, ad hoc and sensor networks, energy constrained communications protocols, and broadband wireless access. He was Editor-In-Chief of IEEE Wireless Communications, 2003–2005, and currently serves on the Editorial Boards of IEEE Transactions on Communications, IEEE Transactions on Wireless Communications, Wiley’s Journal of Wireless Communications and Mobile Computing, and ACM/URSI/Kluwer Journal of Wireless Networks, and on the Steering Committee of the IEEE Transactions on Mobile Computing. He has also been a Guest Editor of special issues in IEEE Personal Communications (Energy Management in Personal Communications Systems) and IEEE Journal on Selected Areas in Communications (Multimedia Network Radios).     

Location-aware resource management in mobile ad hoc networks

We propose an innovative resource management scheme for TDMA based mobile ad hoc networks. Since communications between some important nodes in the network are more critical, they should be accepted by the network with high priority in terms of network resource usage and quality of service (QoS) support. In this scheme, we design a location-aware bandwidth pre-reservation mechanism, which takes advantage of each mobile node’s geographic location information to pre-reserve bandwidth for such high priority connections and thus greatly reduces potential scheduling conflicts for transmissions. In addition, an end-to-end bandwidth calculation and reservation algorithm is proposed to make use of the pre-reserved bandwidth. In this way, time slot collisions among different connections and in adjacent wireless links along a connection can be reduced so that more high priority connections can be accepted into the network without seriously hurting admissions of other connections. The salient feature of our scheme is the collaboration between the routing and MAC layer that results in the more efficient spatial reuse of limited resources, which demonstrates how cross-layer design leads to better performance in QoS support. Extensive simulations show that our scheme can successfully provide better communication quality to important nodes at a relatively low price. Finally, several design issues and future work are discussed. Xiang Chen received the B.E. and M.E. degrees in electrical engineering from Shanghai Jiao Tong University, Shanghai, China, in 1997 and 2000, respectively. Afterwards, he worked as a MTS (member of technical staff) in Bell Laboratories, Beijing, China. He is currently working toward the Ph.D. degree in the department of Electrical and Computer Engineering at the University of Florida. His research is focused on protocol design and performance evaluation in wireless networks, including cellular networks, wireless LANs, and mobile ad hoc networks. He is a member of Tau Beta Pi and a student member of IEEE. Wei Liu received the BE and ME degrees in electrical engineering from Huazhong University of Science and Technology, Wuhan, China, in 1998 and 2001, respectively. He is currently pursuing the P.hD. degree in the Department of Electrical and Computer Engineering, University of Florida, Gainesville, where he is a research assistant in the Wireless Networks Laboratory (WINET). His research interest includes QoS, secure and power efficient routing, and MAC protocols in mobile ad hoc networks and sensor networks. He is a student member of the IEEE. Hongqiang Zhai received the B.E. and M.E. degrees in electrical engineering from Tsinghua University, Beijing, China, in July 1999 and January 2002 respectively. He worked as a research intern in Bell Labs Research China from June 2001 to December 2001, and in Microsoft Research Asia from January 2002 to July 2002. Currently he is pursuing the Ph.D. degree in the Department of Electrical and Computer Engineering, University of Florida. He is a student member of IEEE. 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, IEEETransactions 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).     

QoS Aware Multi-Channel Scheduling for IEEE 802.15.3 Networks

From a multimedia applications perspective, there is an ever increasing demand for wireless devices with higher bandwidth to support high data rate flows. One possible solution to support the demand for higher bandwidth is to utilize the full spectrum by simultaneously using multiple channels for transmission. Recent approval by the Federal Communications Commission (FCC) has led to considerable interest in exploiting Ultra Wideband (UWB) access on an unlicensed basis in the 3.1--10.6 GHz band. Currently, the IEEE TG802.15.3a standards group is in the process of developing an alternative high-speed link layer design conformable with the IEEE 802.15.3 Wireless Personal Area Network (WPAN) multiple access (MAC) protocol. One of the proposals, based on the concept of Orthogonal Frequency Division Multiplexing (OFDM), divides the spectrum into multiple bands and achieves channelization through the use of different time-frequency codes. These multiple channels can help satisfy the increasing demand for higher bandwidth in order to support high data rate multimedia applications. In this paper, we present a QoS-aware, multi-channel scheduling algorithm that simultaneously utilizes the various channels available in the UWB network. Aniruddha Rangnekar is a doctoral student in the Department of Computer Science and Electrical Engineering at the University of Maryland, Baltimore County. He received the B.E. degree in Computer Engineering from the University of Pune, India in 1998 and a M.S. in Computer Science from the University of Maryland, Baltimore County in 2001. From January 2002 to date, he has been involved in graduate research in University of Maryland, Baltimore County. During the summer of 2004, he worked as the MAC development engineer at Staccato Communications, San Diego, CA. His current interests are in the areas of wireless ad hoc networks, multicast routing protocols, ultra wideband communications and MAC protocol development. He is a member of the MACSim group of the Multiband OFDM alliance (MBOA). Krishna M. Sivalingam is an Associate Professor in the Dept. of CSEE at University of Maryland, Baltimore County. Previously, he was with the School of EECS at Washington State University, Pullman from 1997 until 2002; and with the University of North Carolina Greensboro from 1994 until 1997. He has also conducted research at Lucent Technologies' Bell Labs in Murray Hill, NJ, and at AT&T Labs in Whippany, NJ. He received his Ph.D. and M.S. degrees in Computer Science from State University of New York at Buffalo in 1994 and 1990 respectively; and his B.E. degree in Computer Science and Engineering in 1988 from Anna University, Chennai (Madras), India. While at SUNY Buffalo, he was a Presidential Fellow from 1988 to 1991. His research interests include wireless networks, optical wavelength division multiplexed networks, and performance evaluation. He holds three patents in wireless networks and has published several research articles including more than thirty journal publications. He has published an edited book on Wireless Sensor Networks in 2004 and edited books on optical WDM networks in 2000 and 2004. He served as a Guest Co-Editor for special issues of the ACM MONET journal on “Wireless Sensor Networks” in 2003 and 2004; and an issue of the IEEE Journal on Selected Areas in Communications on optical WDM networks (2000). He is co-recipient of the Best Paper Award at the IEEE International Conference on Networks 2000 held in Singapore. His work has been supported by several sources including AFOSR, NSF, Cisco, Intel and Laboratory for Telecommunication Sciences. He is a member of the Editorial Board for ACM Wireless Networks Journal, IEEE Transactions on Mobile Computing, Ad Hoc and Sensor Wireless Networks Journal, and KICS Journal of Computer Networks. He serves as Steering Committee Co-Chair for the International Conference on Broadband Networks (BroadNets) that was created in 2004. He is currently serving as General Co-Vice-Chair for the Second Annual International Mobiquitous conference to be held in San Diego in 2005 and as General Co-Chair for the First International Conference on Security and Privacy for Emerging Areas in Communication Networks to be held in Athens, Greece in Sep. 2005. He served as Technical Program Co-Chair for the First IEEE Conference on Sensor and Ad Hoc Communications and Networks (SECON) held at Santa Clara, CA in 2004; as General Co-Chair for SPIE Opticomm 2003 (Dallas, TX) and for ACM Intl. Workshop on Wireless Sensor Networks and Applications (WSNA) 2003 held in conjunction with ACM MobiCom 2003 at San Diego, CA; as Technical Program Co-Chair of SPIE/IEEE/ACM OptiComm conference at Boston, MA in July 2002; and as Workshop Co-Chair for WSNA 2002 held in conjunction with ACM MobiCom 2002 at Atlanta, GA in Sep 2002. He is a Senior Member of IEEE and a member of ACM.     

Statistical multiplexing, admission region, and contention window optimization in multiclass wireless LANs

This paper presents an analytical model for evaluating the statistical multiplexing effect, admission region, and contention window design in multiclass wireless local area networks (WLANs). We consider distributed medium access control (MAC) which provisions service differentiation by assigning different contention windows to different classes. Mobile nodes belonging to different classes may have heterogeneous traffic arrival processes with different quality of service (QoS) requirements. With bursty input traffic, e.g. on/off sources, our analysis shows that the WLAN admission region under the QoS constraint can be significantly improved, when the statistical multiplexing effect is taken into account. We also analyze the MAC resource sharing between the short-range dependent (SRD) on/off sources and the long-range dependent (LRD) fractional Brownian motion (FBM) traffic, where the impact of the Hurst parameter on the admission region is investigated. Moveover, we demonstrate that the proper selection of contention windows plays an important role in improving the WLAN’s QoS capability, while the optimal contention window for each class and the maximum admission region can be jointly solved in our analytical model. The analysis accuracy and the resource utilization improvement from statistical multiplexing gain and contention window optimization are demonstrated by extensive numerical results. Yu Cheng received the B.E. and M.E. degrees in Electrical Engineering from Tsinghua University, Beijing, China, in 1995 and 1998, respectively, and the Ph.D. degree in Electrical and Computer Engineering from the University of Waterloo, Waterloo, Ontario, Canada, in 2003. From September 2004 to July 2006, he was a postdoctoral research fellow in the Department of Electrical and Computer Engineering, University of Toronto, Ontario, Canada. Since August 2006, he has been with the Department of Electrical and Computer Engineering, Illinois Institute of Technology, Chicago, Illinois, USA, as an Assistant Professor. His research interests include service and application oriented networking, autonomic network management, Internet performance analysis, resource allocation, wireless networks, and wireless/wireline interworking. He received a Postdoctoral Fellowship Award from the Natural Sciences and Engineering Research Council of Canada (NSERC) in 2004. Xinhua Ling received the B. Eng. degree in Radio Engineering from Southeast University, Nanjing, China in 1993 and the M. Eng. degree in Electrical Engineering from the National University of Singapore, Singapore in 2001. He is currently pursuing the Ph.D. degree in the Department of Electrical and Computer Engineering at the University of Waterloo, Ontario, Canada. From 1993 to 1998, he was an R&D Engineer in Beijing Institute of Radio Measurement, China. From February 2001 to September 2002, he was with the Centre for Wireless Communications (currently Institute for Infocom Research), Singapore, as a Senior R&D Engineer, developing the protocol stack for UE in the UMTS system. His general research interests are in the areas of cellular, WLAN, WPAN, mesh and ad hoc networks and their internetworking, focusing on protocol design and performance analysis. Lin X. Cai received the B.Sc. degree in computer science from Nanjing University of Science and Technology, Nanjing, China, in 1996 and the MASc. degree in electrical and computer engineering from the University of Waterloo, Waterloo, Canada, in 2005. She is currently working toward the Ph.D. degree in the same field at the University of Waterloo. Her current research interests include network performance analysis and protocol design for multimedia applications over wireless networks. Wei Song received the B.S. degree in electrical engineering from Hebei University, China, in 1998 and the M.S. degree in computer science from Beijing University of Posts and Telecommunications, China, in 2001. She is currently working toward the Ph.D. degree at the Department of Electrical and Computer Engineering, University of Waterloo, Canada. Her current research interests include resource allocation and quality-of-service (QoS) provisioning for the integrated cellular networks and wireless local area networks (WLANs). Weihua Zhuang received the Ph.D. degree in electrical engineering from the University of New Brunswick, Canada. Since October 1993, she has been with the Department of Electrical and Computer Engineering, University of Waterloo, Canada, where she is a Professor. Dr. Zhuang is a co-author of the textbook Wireless Communications and Networking (Prentice Hall, 2003). Her current research interests include multimedia wireless communications, wireless networks, and radio positioning. She received the Outstanding Performance Award in 2005 and 2006 from the University of Waterloo and the Premier’s Research Excellence Award in 2001 from the Ontario Government for demonstrated excellence of scientific and academic contributions. She is the Editor-in-Chief of IEEE Transactions on Vehicular Technology and an Editor of IEEE Transactions on Wireless Communications. Xuemin (Sherman) Shen received the B.Sc.(1982) degree from Dalian Maritime University (China) and the M.Sc. (1987) and Ph.D. degrees (1990) from Rutgers University, New Jersey (USA), all in electrical engineering. He is a Professor and the Associate Chair for Graduate Studies, Department of Electrical and Computer Engineering, University of Waterloo, Canada. His research focuses on mobility and resource management in interconnected wireless/wired networks, UWB wireless communications systems, wireless security, and ad hoc and sensor networks. He is a co-author of three books, and has published more than 300 papers and book chapters in wireless communications and networks, control and filtering. Dr. Shen serves as the Technical Program Committee Chair for IEEE Globecom’07, General Co-Chair for Chinacom’07 and QShine’06, the Founding Chair for IEEE Communications Society Technical Committee on P2P Communications and Networking. He also serves as a Founding Area Editor for IEEE Transactions on Wireless Communications; Associate Editor for IEEE Transactions on Vehicular Technology; KICS/IEEE Journal of Communications and Networks; Computer Networks (Elsevier); ACM/Wireless Networks; and Wireless Communications and Mobile Computing (John Wiley), etc. He has also served as Guest Editor for IEEE JSAC, IEEE Wireless Communications, and IEEE Communications Magazine. Dr. Shen received the Excellent Graduate Supervision Award in 2006, and the Outstanding Performance Award in 2004 from the University of Waterloo, the Premier’s Research Excellence Award in 2003 from the Province of Ontario, Canada, and the Distinguished Performance Award in 2002 from the Faculty of Engineering, University of Waterloo. Dr. Shen is a registered Professional Engineer of Ontario, Canada. Alberto Leon-Garcia received the B.S., M.S., and Ph.D. degrees in electrical engineering from the University of Southern California, in 1973, 1974, and 1976 respectively. He is a Full Professor in the Department of Electrical and Computer Engineering, University of Toronto, ON, Canada, and he currently holds the Nortel Institute Chair in Network Architecture and Services. In 1999 he became an IEEE fellow for “For contributions to multiplexing and switching of integrated services traffic”. Dr. Leon-Garcia was Editor for Voice/Data Networks for the IEEE Transactions on Communications from 1983 to 1988 and Editor for the IEEE Information Theory Newsletter from 1982 to 1984. He was Guest Editor of the September 1986 Special Issue on Performance Evaluation of Communications Networks of the IEEE Selected Areas on Communications. He is also author of the textbooks Probability and Random Processes for Electrical Engineering (Reading, MA: Addison-Wesley), and Communication Networks: Fundamental Concepts and Key Architectures (McGraw-Hill), co-authored with Dr. Indra Widjaja.     

Cell-Site Diversity Against Co-Channel Interference in LMDS Networks

LMDS networks are fixed radio systems providing advanced telecommunication services to a variety of users. Millimeter wave frequencies above 20 GHz have been allocated to LMDS systems by ITU-R and CEPT. The design of LMDS systems must take into account how interference affects performance considering the dominant propagation impairments in these frequencies. In the present paper, cell-site diversity, an effective fade mitigation countermeasure for LMDS systems, is considered for the reduction of intersystem interference on downstream LMDS channels. The intersystem cochannel interference may originate from adjacent LMDS networks or from point-to-point links operating at the same frequencies. A physical propagation model for the calculation of carrier-to-interference ratio diversity gain for the downstream channel is presented. Numerical results focus on the impact of frequency of operation, the subscriber's service availability and the climatic conditions on the interference analysis of LMDS networks either using or not cell site diversity. Athanasios D. Panagopoulos was born in Athens, Greece on January 26, 1975. He received the Diploma Degree in Electrical and Computer Engineering (summa cum laude) and the Dr. Engineering Degree from National Technical University of Athens (NTUA) in July 1997 and inAprilxcan l 2002. From May 2002 to July 2003, he had served the Technical Corps of Hellenic Army. In September 2003, he joined School of Pedagogical and Technological Education, as Assistant Professor. He is also Research Assistant in the Wireless & Satellite Communications Group of NTUA. He has published more than eighty papers in international journals and conference proceedings. He is the recipient of URSI General AssemblyYoung ScientistAward in 2002 and 2005 respectively. His research interests include radio communication systems design, wireless and satellite communications networks and the propagation effects on multiple access systems and on communication protocols. He is member of IEEE and member of Technical Chamber of Greece. Konstantinos P. Liolis was born in Athens, Greece in 1981. He received the Diploma degree in electrical and computer engineering from the National Technical University of Athens (NTUA) and the M.Sc. degree in electrical engineering from the University of California, San Diego (UCSD) in July 2004 and December 2005, respectively. He is currently working towards his Ph.D. degree in electrical engineering at NTUA. From September 2004 to December 2005, he was research assistant in the California Institute for Telecommunications and Information Technology (Cal-IT2) within UCSD. Since June 2006, he has been with the European Space Agency Research and Technology Centre (ESA/ESTEC), Noordwijk, The Netherlands. His research interests are in the areas of multiple antenna (MIMO) and multicarrier (OFDM) transmission techniques and their application to broadband fixed wireless access and satellite communication networks. He is student member of the IEEE and member of the Technical Chamber of Greece (TEE). He received the 3rd Best Student Paper Award in the 2006 IEEE Radio and Wireless Symposium. Panayotis G. Cottis was born in Thessaloniki, Greece, in 1956. He received the Dipl. (mechanical and electrical engineering) and Dr.Eng. degrees from the National Technical University of Athens (NTUA), Greece, in 1979 and 1984, respectively, and the M.Sc. degree from the University of Manchester, (UMIST), Manchester, U.K., in 1980. In 1986, he joined the Department of Electrical and Computer Engineering, National Technical University of Athens (NTUA), Greece, where he is currently a Professor. He has published more than seventy papers in international journals and transactions. His research interests include microwave theory and applications, wave propagation in anisotropic media, electromagnetic scattering, wireless and satellite communications. Since September 2003, he is the Vice Rector of NTUA.     

A rendezvous reservation protocol for energy constrained wireless infrastructure networks

This paper considers a low power wireless infrastructure network that uses multi-hop communications to provide end user connectivity. A generalized Rendezvous Reservation Protocol (RRP) is proposed which permits multi-hop infrastructure nodes to adapt their power consumption in a dynamic fashion. When nodes have a long-term association, power consumption can be reduced by having them periodically rendezvous for the purpose of exchanging data packets. In order to support certain applications, the system invokes a connection set up process to establish the end-to-end path and selects node rendezvous rates along the intermediate nodes to meet the application’s quality of service (QoS) needs. Thus, the design challenge is to dynamically determine rendezvous intervals based on incoming applications’ QoS needs, while conserving battery power. In this paper, we present the basic RRP mechanism and an enhanced mechanism called Rendezvous Reservation Protocol with Battery Management (RRP-BM) that incorporates node battery level information. The performance of the system is studied using discrete-event simulation based experiments for different network topologies. The chief metrics considered are average power consumption and system lifetime (that is to be maximized). The QoS metrics specified are packet latency and end-to-end setup latency. It is shown that the use of the RRP-BM can increase the lifetime up to 48% as compared to basic RRP by efficiently reducing the energy consumption. This work was supported by a grant from the Natural Sciences and Engineering Research Council of Canada and Communications and Information Technology Ontario (CITO). Part of the research was supported by Air Force Office of Scientific Research grants F-49620-97-1-0471 and F-49620-99-1-0125; Laboratory for Telecommunications Sciences, Adelphi, Maryland; and Intel Corporation. The authors may be reached via e-mail at todd@mcmaster. ca, krishna@umbc. edu. The basic RRP mechanism was presented at the IASTED International Conference on Wireless and Optical Communications, Banff, Canada, July 2002. Subalakshmi Venugopal received her Bachelors in Computer Science from R.V. College of Engineering, Bangalore, India and her M.S. degree in Computer Science from Washington State University. She interned as a student researcher at the Indian Institute of Science, Bangalore, India. Ms. Venugopal is currently employed with Microsoft Corporation in Redmond, WA and is part of the “Kids and Education Group”. Her research interests include low power wireless ad hoc networks. Zhengwei (Wesley) Chen received the M.E. in Electrical & Computer Engineering Dept from McMaster University in Canada in 2002. He joined Motorola Inc. as a CDMA2000 system engineer in 2000. In 2002, he joined UTStarcom as a manager of the Global Service Solution Department. He is currently in charge of R&D for Advanced Services related to the TVoIP and Softswitch products. Terry Todd received the B.A.Sc, M.A.Sc and Ph.D degrees in Electrical Engineering from the University of Waterloo in Waterloo, Ontario, Canada. While at Waterloo he also spent 3 years as a Research Associate with the Computer Communications Networks Group (CCNG). During that time he worked on the Waterloo Experimental Local Area Network, which was an early local area network testbed. In 1991 Dr. Todd was on research leave in the Distributed Systems Research Department at AT&T Bell Laboratories in Murray Hill, NJ. He also spent 1998 as a visiting researcher at The Olivetti and Oracle Research Laboratory (ORL) in Cambridge, England. While at ORL he worked on the piconet project, which was an embedded low power wireless network testbed. Dr. Todd is currently a Professor of Electrical and Computer Engineering at McMaster University in Hamilton, Ontario, Canada. At McMaster he has been the Principal Investigator on a number of major research projects in the optical and wireless networking areas. He currently directs a large group working on wireless mesh networks and wireless VoIP. Professor Todd holds the NSERC/RIM/CITO Chair on Pico-Cellular Wireless Internet Access Networks. Dr. Todd’s research interests include metropolitan/local area networks, wireless communications and the performance analysis of computer communication networks and systems. Professor Todd is a Professional Engineer in the province of Ontario. Krishna M. Sivalingam is an Associate Professor in the Dept. of CSEE at University of Maryland, Baltimore County. Previously, he was with the School of EECS at Washington State University, Pullman from 1997 until 2002; and with the University of North Carolina Greensboro from 1994 until 1997. He has also conducted research at Lucent Technologies’ Bell Labs in Murray Hill, NJ, and at AT&T Labs in Whippany, NJ. He received his Ph.D. and M.S. degrees in Computer Science from State University of New York at Buffalo in 1994 and 1990 respectively; and his B.E. degree in Computer Science and Engineering in 1988 from Anna University, Chennai (Madras), India. While at SUNY Buffalo, he was a Presidential Fellow from 1988 to 1991. His research interests include wireless networks, optical wavelength division multiplexed networks, and performance evaluation. He holds three patents in wireless networks and has published several research articles including more than thirty journal publications. He has published an edited book on Wireless Sensor Networks in 2004 and edited books on optical WDM networks in 2000 and 2004. He served as a Guest Co-Editor for special issues of the ACM MONET journal on “Wireless Sensor Networks” in 2003 and 2004; and an issue of the IEEE Journal on Selected Areas in Communications on optical WDM networks (2000). He is co-recipient of the Best Paper Award at the IEEE International Conference on Networks 2000 held in Singapore. His work has been supported by several sources including AFOSR, NSF, Cisco, Intel and Laboratory for Telecommunication Sciences. He is a member of the Editorial Board for ACM Wireless Networks Journal, IEEE Transactions on Mobile Computing, Ad Hoc and Sensor Wireless Networks Journal, and KICS Journal of Computer Networks. He serves as Steering Committee Co-Chair for IEEE/CreateNet International Conference on Broadband Networks (BroadNets) that was created in 2004. He is currently serving as General Co-Vice-Chair for the Second Annual International Mobiquitous conference to be held in San Diego in 2005 and as General Co-Chair for the First IEEE/CreateNet International Conference on Security and Privacy for Emerging Areas in Communication Networks (SecureComm) to be held in Athens, Greece in Sep. 2005. He served as Technical Program Co-Chair for the First IEEE Conference on Sensor and Ad Hoc Communications and Networks (SECON) held at Santa Clara, CA in 2004; as General Co-Chair for SPIE Opticomm 2003 (Dallas, TX) and for ACM Intl. Workshop on Wireless Sensor Networks and Applications (WSNA) 2003 held in conjunction with ACM MobiCom 2003 at San Diego, CA; as Technical Program Co-Chair of SPIE/IEEE/ACM OptiComm conference at Boston, MA in July 2002; and as Workshop Co-Chair for WSNA 2002 held in conjunction with ACM MobiCom 2002 at Atlanta, GA in Sep 2002. He is a Senior Member of IEEE and a member of ACM.     

A secure authentication and billing architecture for wireless mesh networks

Wireless mesh networks (WMNs) are gaining growing interest as a promising technology for ubiquitous high-speed network access. While much effort has been made to address issues at physical, data link, and network layers, little attention has been paid to the security aspect central to the realistic deployment of WMNs. We propose UPASS, the first known secure authentication and billing architecture for large-scale WMNs. UPASS features a novel user-broker-operator trust model built upon the conventional certificate-based cryptography and the emerging ID-based cryptography. Based on the trust model, each user is furnished with a universal pass whereby to realize seamless roaming across WMN domains and get ubiquitous network access. In UPASS, the incontestable billing of mobile users is fulfilled through a lightweight realtime micropayment protocol built on the combination of digital signature and one-way hash-chain techniques. Compared to conventional solutions relying on a home-foreign-domain concept, UPASS eliminates the need for establishing bilateral roaming agreements and having realtime interactions between potentially numerous WMN operators. Our UPASS is shown to be secure and lightweight, and thus can be a practical and effective solution for future large-scale WMNs. 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. 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).     

UbiqMuseum: A Bluetooth and Java Based Context-Aware System for Ubiquitous Computing

This paper evaluates the use of Bluetooth and Java based technologies in ubiquitous computing environments. Ubiquitous computing strongly depends on leveraging appropriate contextual information to users, according to their preferences and the environment in which they reside. We present UbiqMuseum – an experimental context-aware application that provides context-aware information to museum visitors. UbiqMuseum combines the productivity of Java with the universal connectivity provided by Bluetooth wireless technology. We describe the overall architecture and discuss the implementation steps taken to create our Bluetooth and Java based context-aware application. We demonstrate practicality of building a context-aware system by using UbiqMuseum as a proof of concept that integrates a combination of Bluetooth, WLAN and Ethernet LAN technologies. Finally we run some experiments in a small testbed to evaluate the performance and system behaviour. We evaluate the impact on throughput with varying packet size, coding types and device separation distance sending both images and text. We also present our findings in term of inquiry delay with respect to distance. Numerical results show that Bluetooth offers a relatively steady throughput up to 10 m while the inquiry delay does not increase significantly with distance. Juan-Carlos Cano is an assistant professor in the Department of Computer Engineering at the Polytechnic University of Valencia (UPV) in Spain. He earned an M.Sc. and a Ph.D. in computer science from the UPV in 1994 and 2002 respectively. Between 1995–1997 he worked as a programming analyst at IBM's manufacturing division in Valencia. His current research interests include power aware routing protocols for mobile ad hoc networks and pervasive computing. You can contact him at jucano@disca.upv.es. Pietro Manzoni received the MS degree in computer science from the “Universitá degli Studi" of Milan, Italy, in 1989, and the Ph.D. degree in computer science from the Polytechnic University of Milan, Italy, in 1995. He is an associate professor of computer science at the Polytechnic University of Valencia, Spain. His research activity is related to wireless networks protocol design, modeling, and implementation. He is member of the IEEE. C.-K. Toh is currently a Professor and Chair in Communication Networks at Queen Mary University of London, UK. He is also the Director of the UK Ad Hoc Wireless Consortium and Director of the Queen Mary/Fudan Joint Research Lab in Mobile Networking and Ubiquitous Computing. Concurrently, he is also an Honorary Professor with the University of Hong Kong and an Adjunct Professor at Fudan University, Shanghai. Previously, he was the Director of Research with TRW Tactical Systems in California, USA (now Northrop Grumman Corporation) and was responsible for DARPA and Army programs in communications and networking. He had also worked for Hughes Research, ALR, HP, and was a professor at GeorgiaTech and University of California, Irvine. CK is the recipient of the 2005 IEEE Kiyo Tomiyasu Technical Medal Award, for “pioneering contributions to communication protocols in ad hoc mobile wireless networks." He is the author of “Wireless ATM & Ad Hoc Networks" (Kluwer Press, 1996) and “Ad Hoc Mobile Wireless Networks" (Prentice Hall Engineering Title Best Seller, 2001–2003). He is a recipient of the ACM Recognition of Service Award, for co-founding ACM MobiHoc Conference. He is a co-recipient of the Korean Science & Engineering Foundation Best Journal paper Award for his work on ad hoc TCP. CK was formerly the Chairman of IEEE Communications Society Technical Committee on Computer Communications and Chairman of IEEE Subcommittee on Ad Hoc Mobile Wireless Networks. He was an IEEE Expert/Distinguished Lecturer and had served as a Steering Committee Member for IEEE WCNC Conference and IEEE Transaction on Mobile Computing. He was a member of IEEE Communications Society Meetings & Conferences Board. CK was an editor for IEEE Networks, IEEE JSAC, IEEE transactions on Wireless Communications, Journal on Communication Networks, and IEEE Distributed Systems. He is a Fellow of four societies: British Computer Society, the IEE, the Hong Kong Institution of Engineers and the New Zealand Computer Society. He received his Ph.D. degree in Computer Science from Cambridge University, England, and his executive education from Harvard.     

Effective Capacity-Based Quality of Service Measures for Wireless Networks

An important objective of next-generation wireless networks is to provide quality of service (QoS) guarantees. This requires a simple and efficient wireless channel model that can easily translate into connection-level QoS measures such as data rate, delay and delay-violation probability. To achieve this, in Wu and Negi (IEEE Trans. on Wireless Communications 2(4) (2003) 630–643), we developed a link-layer channel model termed effective capacity, for the setting of a single hop, constant-bit-rate arrivals, fluid traffic, and wireless channels with negligible propagation delay. In this paper, we apply the effective capacity technique to deriving QoS measures for more general situations, namely, (1) networks with multiple wireless links, (2) variable-bit-rate sources, (3) packetized traffic, and (4) wireless channels with non-negligible propagation delay. 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. From July 1997 to December 1999, he conducted graduate research at Polytechnic University, Brooklyn, New York. During the summers of 1998, 1999 and 2000, he conducted research at Fujitsu Laboratories of America, Sunnyvale, California, on architectures and traffic management algorithms in the Internet and wireless networks for multimedia applications. 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. Currently, he is an Associate Editor for the IEEE Transactions on Vehicular Technology and Associate Editor for International Journal of Ad Hoc and Ubiquitous Computing. He served as Program Chair for IEEE/ACM First International Workshop on Broadband Wireless Services and Applications (BroadWISE 2004); and as TPC member of over 20 conferences such as IEEE INFOCOM'05, IEEE ICC'05, IEEE WCNC'05, and IEEE Globecom'04. 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 Award Committee, Technical Committee on Multimedia Communications, IEEE Communications Society. He is also Director of Communications, IEEE Gainesville Section. Rohit Negi received the B.Tech. degree in Electrical Engineering from the Indian Institute of Technology, Bombay, India in 1995. He received the M.S. and Ph.D. degrees from Stanford University, CA, USA, in 1996 and 2000 respectively, both in Electrical Engineering. He has received the President of India Gold medal in 1995. Since 2000, he has been with the Electrical and Computer Engineering department at Carnegie Mellon University, Pittsburgh, PA, USA, where he is an Assistant Professor. His research interests include signal processing, coding for communications systems, information theory, networking, cross-layer optimization and sensor networks.     

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).     

QoS Mechanisms for the MAC Protocol of IEEE 802.11 WLANs

There are two essential ingredients in order for any telecommunications system to be able to provide Quality-of-Service (QoS) guarantees: connection admission control (CAC) and service differentiation. In wireless local area networks (WLANs), it is essential to carry out these functions at the MAC level. The original version of IEEE 802.11 medium access control (MAC) protocol for WLANs does not include either function. The IEEE 802.11e draft standard includes new features to facilitate and promote the provision of QoS guarantees, but no specific mechanisms are defined in the protocol to avoid over saturating the medium (via CAC) or to decide how to assign the available resources (via service differentiation through scheduling). This paper introduces specific mechanisms for both admission control and service differentiation into the IEEE 802.11 MAC protocol. The main contributions of this work are a novel CAC algorithm for leaky-bucket constrained traffic streams, an original frame scheduling mechanism referred to as DM-SCFQ, and a simulation study of the performance of a WLAN including these features. This work has been partly funded by the Mexican Science and Technology Council (CONACYT) through grant 38833-A. José R. Gallardo received the B.Sc. degree in Physics and Mathematics from the National Polytechnic Institute in Mexico City, the M.Sc. degree in Electrical Engineering from CICESE Research and Graduate Education Center in Ensenada, Mexico, and the D.Sc. degree in Electrical Engineering from the George Washington University, Washington, DC. From 1997 to 2000 he worked as a Research Associate at the Advanced Communications Engineering Centre of the University of Western Ontario, London, Ontario, Canada. From May to December 2000, he worked as a Postdoctoral Fellow at the Broadband Wireless and Internetworking Research Laboratory of the University of Ottawa. Since December 2000, Dr. Gallardo has been with the Electronics and Telecommunications Department of CICESE Research Center, where he is a full professor. His main areas of interest are traffic modeling, traffic control, as well as simulation and performance evaluation of broadband communications networks, with recent emphasis on wireless local area networks (WLANs) and wireless sensor networks (WSNs). Paúl Medina received the B.Eng. degree from the Sonora Institute of Technology, Obregon, Mexico, and the M.Sc. degree from CICESE Research and Graduate Education Center, Ensenada, Mexico, both in Electrical Engineering. From July to September 2005, he worked as a Research Associate at the Broadband Wireless and Internetworking Research Laboratory of the University of Ottawa, Canada. Mr. Medina is currently with CENI²T, Ensenada, Mexico, working as a lead engineer in projects related to routing and access control in wireless sensor networks, as well as IP telephony over wireless LANs. Weihua Zhuang received the B.Eng. and M.Eng. degrees from Dalian Maritime University, Liaoning, China, and the Ph.D. degree from the University of New Brunswick, Canada, all in electrical engineering. Since October 1993, she has been with the Department of Electrical and Computer Engineering, University of Waterloo, ON, Canada, where she is a full professor. She is a co-author of the textbook Wireless Communications and Networking (Prentice Hall, 2003). Dr. Zhuang received the Outstanding Performance Award in 2005 from the University of Waterloo, and the Premier’s Research Excellence Award in 2001 from the Ontario Government. She is an Editor/Associate Editor of IEEE Transactions on Wireless Communications, IEEE Transactions on Vehicular Technology, EURASIP Journal on Wireless Communications and Networking, and International Journal of Sensor Networks. Her current research interests include multimedia wireless communications, wireless networks, and radio positioning.     

Performance Analysis of Header Compression Schemes in Heterogeneous Wireless Multi–Hop Networks

Wireless multi–hop networks are becoming more popular and the demand for multimedia services in these networks rises with the number of their implementations. Header compression schemes that compress the IP/UDP/RTP headers to save bandwidth for multimedia streams were typically evaluated only for individual links, not taking into account the savings that can be achieved using header compression over a complete path. In this paper, we evaluate the performance of three categories of header compression schemes: (i) delta coding, (ii) framed delta coding, and (iii) framed referential coding. We evaluate the performance for these schemes on reliable and unreliable links. We then extend our evaluations to several links constituting a path. As nodes in multi–hop ad-hoc and mesh networks may differ with respect to their capabilities, we assume in our evaluation that (forwarding) nodes may not be able or choose not to perform header compression. We find that the framed referential header compression scheme is the most suitable scheme in case that no or long-delay feedback channels exist. We additionally compare the packet drop savings due to header compression and the combined savings of compression and drops. We again find that the framed referential coding scheme exhibits good performance that can lead to significant header compression and packet drop savings for reasonable bit error rates. Patrick Seeling is a Faculty Research Associate in the Department of Electrical Engineering at Arizona State University (ASU), Tempe. He received the Dipl.-Ing. degree in Industrial Engineering and Management (specializing in electrical engineering) from the Technical University of Berlin (TUB), Germany, in 2002. He received his Ph.D. in electrical engineering from Arizona State University, Arizona, in 2005. His research interests are in the area of multimedia communications in wired and wireless networks and engineering education. He is a member of the IEEE and the ACM. Martin Reisslein is an Associate Professor in the Department of Electrical Engineering at Arizona State University (ASU), Tempe. He received the Dipl.-Ing. (FH) degree from the Fachhochschule Dieburg, Germany, in 1994, and the M.S.E. degree from the University of Pennsylvania, Philadelphia, in 1996. Both in electrical engineering. He received his Ph.D. in systems engineering from the University of Pennsylvania in 1998. During the academic year 1994–1995 he visited the University of Pennsylvania as a Fulbright scholar. From July 1998 through October 2000 he was a scientist with the German National Research Center for Information Technology (GMD FOKUS), Berlin and lecturer at the Technical University Berlin. From October 2000 through August 2005 he was an Assistant Professor at ASU. He is editor-in-chief of the IEEE Communications Surveys and Tutorials and has served on the Technical Program Committees of IEEE Infocom, IEEE Globecom, and the IEEE International Symposium on Computer and Communications. He has organized sessions at the IEEE Computer Communications Workshop (CCW). He maintains an extensive library of video traces for network performance evaluation, including frame size traces of MPEG-4 and H.263 encoded video, at http://trace.eas.asu.edu. He is co-recipient of the Best Paper Award of the SPIE Photonics East 2000 – Terabit Optical Networking conference. His research interests are in the areas of Internet Quality of Service, video traffic characterization, wireless networking, optical networking, and engineering education. Tatiana K. Madsen has received her M.Sc. and Ph.D. degrees in Mathematics from Moscow State University, Russia in 1997 and 2000, respectively. In 2001 she joined Dept. of Communication Technology, Aalborg University, Denmark where she is currently an Assistant Professor. Her research interests lie within the areas of wireless networking with the focus on IP header compression techniques and mathematical modeling of wireless protocols behavior. Frank Fitzek is an Associate Professor in the Department of Communication Technology, Unversity of Aalborg, Denmark heading the Future Vision gorup. He received his diploma (Dipl.-Ing.) degree in electrical engineering from the University of Technology – Rheinish-Westflische Technische Hochschule (RWTH) – Aachen, Germany, in 1997 and his Ph.D. (Dr.-Ing.) in Electrical Engineering from the Technical Univeristy Berlin, Germany in 2002 for quality of service support in wireless CDMA networks. As a visiting student at the Arizona State University he conducted research in the field of video services over wireless networks. He co-founded the start-up company acticom GmbH in Berlin in 1999. In 2002 he was Adjunct Professor at the University of Ferrara, Italy giving lectures on wireless communications and conducting research on multi-hop networks. In 2005 he won the YRP award for the work on MIMO MDC. His current research interests are in the areas of 4G wireless communication networks and cooperative networking. Dr. Fitzek serves on the Editorial Board of the IEEE Communications Surveys and Tutorials.     

Auction-Based Spectrum Sharing

We study auction mechanisms for sharing spectrum among a group of users, subject to a constraint on the interference temperature at a measurement point. The users access the channel using spread spectrum signaling and so interfere with each other. Each user receives a utility that is a function of the received signal-to-interference plus noise ratio. We propose two auction mechanisms for allocating the received power. The first is an auction in which users are charged for received SINR, which, when combined with logarithmic utilities, leads to a weighted max-min fair SINR allocation. The second is an auction in which users are charged for power, which maximizes the total utility when the bandwidth is large enough and the receivers are co-located. Both auction mechanisms are shown to be socially optimal for a limiting “large system” with co-located receivers, where bandwidth, power and the number of users are increased in fixed proportion. We also formulate an iterative and distributed bid updating algorithm, and specify conditions under which this algorithm converges globally to the Nash equilibrium of the auction. This work was supported by the Northwestern-Motorola Center for Communications and by NSF CAREER award CCR-0238382. This paper was presented in part at the 2nd Workshop on Modeling and Optimization in Mobile, Ad Hoc, and Wireless Networks (WiOpt’04), Cambridge, UK, March 24–26, 2004, and the 42nd Annual Allerton Conference on Communication, Control and Computing, Monticello, IL, USA, September 29 - October 1, 2004. Jianwei Huang received the B.E. degree in Radio Engineering from Southeast University, Nanjing, China in 2000, and the M.S. and Ph.D. degrees in Electrical and Computer Engineering from Northwestern University, Evanston, IL in 2003 and 2005, respectively. He is currently a Postdoc Research Association in the Department of Electrical Engineering, Prinston university, NJ. In 2004 and 2005, he also worked in the Mathematics of Communication Networks Group at Motorola, Arlington Heights, IL USA as a software engineer. His current research interests lie in the areas of wireless and wireline communications networks, with emphases on resource allocation, network pricing, dynamic spectrum sharing, mobile ad hoc and sensor networks, stochastics and non-convex optimizations. Dr. Huang is the receipt of a 2001 Walter P. Murphy Fellowship at Northwestern University, and a 1999 Chinese National Excellent Student Award. Randall A. Berry received the B.S. degree in Electrical Engineering from the University of Missouri-Rolla in 1993 and the M.S. and Ph.D. degrees in Electrical Engineering and Computer Science from the Massachusetts Institute of Technology in 1996 and 2000 respectively. He is currently an assistant professor in the Department of Electrical Engineering and Computer Science at Northwestern University. In 1998 he was on the technical staff at MIT Lincoln Laboratory in the Advanced Networks Group. His primary research interests include wireless communication, data networks, and information theory. He is the recipient of a 2003 NSF CAREER award. Michael L. Honig received the B.S. degree in electrical engineering from Stanford University in 1977, and the M.S. and Ph.D. degrees in electrical engineering from the University of California, Berkeley, in 1978 and 1981, respectively. He subsequently joined Bell Laboratories in Holmdel, NJ, where he worked on local area networks and voiceband data transmission. In 1983 he joined the Systems Principles Research Division at Bellcore, where he worked on Digital Subscriber Lines and wireless communications. Since the Fall of 1994, he has been with Northwestern University where he is a Professor in the Electrical Engineering and Computer Science Department. He has held visiting scholar positions at the Naval Research Laboratory (San Diego), the University of California, Berkeley, the University of Sydney, and Princeton University. He has also worked as a free-lance trombonist. Dr. Honig has served as an editor for the IEEE Transactions on Information Theory (1998-2000) and the IEEE Transactions on Communications (1990-1995), and was a guest editor for the European Transactions on Telecommunications and Wireless Personal Communications. He has also served as a member of the Digital Signal Processing Technical Committee for the IEEE Signal Processing Society, and as a member of the Board of Governors for the Information Theory Society (1997-2002). He is the co-recipient of the 2002 IEEE Communications Society and Information Theory Society Joint Paper Award, and is a Fellow of IEEE.     

A new approach to peer-to-peer wireless LANs based on ultra wide band technology

The advent of Ultra Wide Band (UWB) technology offers a unique opportunity to consider a new type of peer-to-peer wireless Local Area Network (LAN) that requires neither access at a peak data rate commensurate with the full bandwidth of the medium nor a conventional medium access protocol. Rather, due to the extraordinarily high bandwidth afforded by UWB, which is typically much greater than the peak bandwidth required by any ad-hoc radio node, one might imagine a network for which pairs of nodes are interconnected by one or more dedicated (non-shared) radio channels created by time, frequency, or code division multiplexing. In this paper, we consider a network containing N ad-hoc nodes and 2N independent radio channels. Starting with (1) an N × N power matrix, where element p _i,j represents the power needed for a successful transmission from node i to node j including the effects of path loss and shadow fading, and (2) a second N × N traffic matrix where element t _i,j represents the exogenous traffic originating from node i and destined for node j, we seek to assign radio channels and multi-hop route the traffic between source-destination pairs such that the resulting connectivity pattern and traffic flow minimize the average transmit energy needed to deliver a packet between an arbitrarily chosen pair of nodes. With no medium access protocol needed, collisions cannot occur and retransmissions become unnecessary. Moreover, the available capacity grows with the number of channels created (or, alternatively, as some common set of channels are re-used on a non-interfering basis via sufficient spatial separation). In this fashion, such a UWB ad-hoc network takes on the characteristics of a multi-hop Wavelength-Division Multiplexed (WDM) network well known from the multihop lightwave network art, although the constraints and dynamics are certainly different. Since the optimum connectivity and flow problem is shown to be NP hard, several heuristics are considered and compared. These heuristics seek, first, to establish a “good” connectivity graph, and then to flow the traffic in an optimum fashion. Our results suggest that application of these techniques may provide a distinct wireless LAN advantage achievable only via UWB radio technology, and several opportunities for future work based on this novel approach to ad-hoc local area radio networks are identified and discussed. Marc Krull received his B.S. degree in electrical engineering from Brown University in 2001 and his M.S. degree in electrical engineering from the University of California, San Diego in 2004. His graduate research focused on the investigation of energy efficient routing protocols for ultrawideband networks. He is currently with Raytheon Companys Intelligence and Information Systems division in Aurora, Colorado, where he is involved in software development for satellite ground systems. Anthony Acampora is a Professor of Electrical and Computer Engineering at the University of California, San Diego, and is involved in numerous research projects addressing various issues at the leading edge of telecommunication networks, including the Internet, ATM, broadband wireless access, network management and dense wavelength division multiplexing. From 1995 through 1999, he was Director of UCSDs Center for Wireless Communications, responsible for an industrially funded research effort which included circuits, signal processing, smart antennas, basic communication theory, wireless telecommunications networks, infrastructure for wireless communications, and software for mobility. Prior to joining the faculty at UCSD in 1995, he was Professor of Electrical Engineering at Columbia University and Director of the Center for Telecommunications Research, a National Science Foundation Engineering Research Center. He joined the faculty at Columbia in 1988 following a 20-year career at AT&T Bell Laboratories, most of which was spent in basic research where his interests included radio and satellite communications, local and metropolitan area networks, packet switching, wireless access systems, and lightwave networks. His most recent position at Bell Labs was Director of the Transmission Technology Laboratory where he was responsible for a wide range of projects, including broadband networks, image communications, and digital signal processing. At Columbia, he was involved in research and education programs concerning broadband networks, wireless access networks, network management, optical networks and multimedia applications. He received his PhD. in Electrical Engineering from the Polytechnic Institute of Brooklyn and is Fellow of the IEEE and a former member of the IEEE Communication Society Board of Governors. Professor Acampora has published over 160 papers, holds 33 patents, and has authored a textbook entitled An Introduction to Broadband Networks: MANs, ATM, B-ISDN, Self Routing Switches, Optical Networks, and Network Control for Voice, Data, Image and HDTV Telecommunications. He sits on numerous telecommunications advisory committees and frequently serves as a consultant to government and industry.     

Strongly Consistent Access Algorithms for Wireless Data Networks

In wireless data networks such as the WAP systems, the cached data may be time-sensitive and strong consistency must be maintained (i.e., the data presented to the user at the WAP handset must be the same as that in the origin server). In this paper, we study the cached data access algorithms in such systems. Two caching algorithms are investigated. In Algorithm I, Pull-Each-Read, whenever a data access occurs, the client always asks the server whether the cached entry in the client is valid or not. In Algorithm II, Callback, the server always invalidates the cached entry in the client whenever an update occurs. Analytic models are proposed to evaluate the performance of these algorithms. Our studies show that Algorithm II outperforms Algorithm I if the data access rate is high and the access pattern is irregular. We also design an adaptive mechanism to effectively switch between the two algorithms to take advantages of both algorithms. We also apply the single-level cached data access algorithms for the multi-level cache hierarchy. Our study indicates that with appropriate arrangement, strongly consistent cached data access for wireless Internet (such as WAP) can be efficiently supported.Yuguang Fang received the B.S. and M.S. degrees in Mathematics from Qufu Normal University, Qufu, Shandong, China, in 1984 and 1987, respectively, a Ph.D degree from Department of Systems, Control and Industrial Engineering at Case Western Reserve University, Cleveland, Ohio, in January 1994, and a Ph.D degree from Department of Electrical and Computer Engineering at Boston University, Massachusetts, in May 1997.From 1987 to 1988, he held research and teaching positions in both Department of Mathematics and the Institute of Automation at Qufu Normal University. He held a post-doctoral position in Department of Electrical and Computer Engineering at Boston University from June 1994 to August 1995. 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. From May 2000 to July 2003, he was an Assistant Professor in the Department of Electrical and Computer Engineering at University of Florida, Gainesville, Florida, where he has been an Associate Professor since August 2003. His research interests span many areas including wireless networks, mobile computing, mobile communications, automatic control, and neural networks. He has published over ninety papers in refereed professional journals and conferences. He received the National Science Foundation Faculty Early Career Development Award in 2001 and the Office of Naval Research Young Investigator Award in 2002. He is listed in Marquis Whos Who in Science and Engineering, Whos Who in America and Whos 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 ACM Wireless Networks, an Area Editor for ACM Mobile Computing and Communications Review, an Associate Editor for Wiley International Journal on Wireless Communications and Mobile Computing, and an Editor for IEEE Wireless Communications. He was an Editor for IEEE Journal on Selected Areas in Communications: Wireless Communications Series and the feature editor for Scanning the Literature in IEEE Wireless Communications (formerly IEEE Personal Communications). He has also actively involved with many professional conferences such as ACM MobiCom02, ACM MobiCom01, IEEE INFOCOM04, INFOCOM03, INFOCOM00, INFOCOM98, IEEE WCNC02, WCNC00 (Technical Program Vice-Chair), WCNC99, and International Conference on Computer Communications and Networking (IC3N98) (Technical Program Vice-Chair).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.Dr. Lin is a senior technical editor of IEEE Network, an editor of IEEE Trans. on Wireless Communications, an associate editor of IEEE Trans. on Vehicular Technology, an associate editor of IEEE Communications Survey and Tutorials, an editor of IEEE Personal Communications Magazine, an editor of Computer Networks, an area editor of ACM Mobile Computing and Communication Review, a columnist of ACM Simulation Digest, an editor of International Journal of Communications Systems, an editor of ACM/Baltzer Wireless Networks, an editor of Computer Simulation Modeling and Analysis, an editor of Journal of Information Science and Engineering, Program Chair for the 8th Workshop on Distributed and Parallel Simulation, General Chair for the 9th Workshop on Distributed and Parallel Simulation. Program Chair for the 2nd International Mobile Computing Conference, Guest Editor for the ACM/Baltzer MONET special issue on Personal Communications, a Guest Editor for IEEE Transactions on Computers special issue on Mobile Computing, a Guest Editor for IEEE Transactions on Computers special issue on Wireless Internet, and a Guest Editor for IEEE Communications Magazine special issue on Active, Programmable, and Mobile Code Networking. Lin is the author of the book Wireless and Mobile Network Architecture (co-author with Imrich Chlamtac; published by John Wiley & Sons). Lin received 1998, 2000 and 2002 Outstanding Research Awards from National Science Council, ROC, and 1998 Outstanding Youth Electrical Engineer Award from CIEE, ROC. He also received the NCTU Outstanding Teaching Award in 2002. 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.     

Providing Throughput Guarantees in 802.11e WLAN Through a Dynamic Priority Assignment Mechanism

Supporting real-time and interactive traffic in addition to traditional data traffic with a best-effort nature represents a constantly rising need in any kind of telecommunications environment. The IEEE 802.11 based WLAN (Wireless Local Area Network) environment does not represent an exception. This is why at different protocol layers, and primarily at the MAC layer, many efforts are being put by both the research community and the standardization bodies to design effective mechanisms for user QoS (Quality of Service) differentiation. Although early results are coming into sight, such as, for example, the IEEE 802.11e standard release, still a thorough research activity is required. Aim of the present paper is to contribute to the cited research issue by proposing an improvement to the “static” traffic prioritisation mechanism foreseen by the IEEE 802.11e MAC (Medium Access Control) protocol. This latter shows a twofold drawback. First, there is no certainty that QoS requirements relevant to a given application are always fulfilled by the “statically” associated priority. Second, resource requests of the applications are not adapted to the (usually highly) variable traffic conditions of a distributed WLAN environment. The algorithm we propose is specifically tailored to “dynamically” assign 802.11e MAC priorities, depending on both application QoS requirements and observed network congestion conditions. It is carefully designed, implemented into a system simulation tool, and its highly effective behaviour assessed under variable traffic and system conditions. Antonio Iera graduated in Computer Engineering at the University of Calabria, Italy, in 1991 and received a Master Diploma in Information Technology from CEFRIEL/Politecnico di Milano, Italy, in 1992 and a Ph.D. degree from the University of Calabria, Italy, in 1996. From 1994 to 1995 he has been at the Mobile Network Division Research Center, Siemens AG Muenchen, Germany to participate to the CEC Project “RACE II 2084 ATDMA (Advanced TDMA Mobile Access)” under a “Commission of European Communities Fellowship Contract in RACE Mobility Action”. He has been with the University of Reggio Calabria, Italy, from 1997 to 2000 as Assistant Professor, and from 2001 to 2005 as Associate Professor. Currently, he is Full Professor of Telecommunications at the same University. In 1995 and in 1996 he has been the recipient of an IEEE Paper Award for the papers presented at the IEEE International Conference on Universal Personal Communications ICUPC'95, and an IEICE/IEEE Outstanding Paper Award for the paper presented at the IEEE ATM Workshop'99, respectively. He served as member of Technical Program Committees of several International Conferences, and in 2003 he has been co-Guest Editor for the special issue “QoS in Next-generation Wireless Multimedia Communications Systems” in the IEEE Wireless Communications Magazine. His research interests include QoS control and resource management in Personal Communications Systems and Enhanced Wireless and Satellite Systems. Giuseppe Ruggeri received the degree in electronics engineering from the University of Catania, Italy, in 1998. He received the Ph.D. degree in electronics, computer science and telecommunications engineering with a dissertation on “Advanced Methods to Improve the QoS in VoIP Systems Based on VBR Speech Coders”. His interests include the field of adaptive-rate voice transmission for IP Telephony applications, and support of Quality of Service in heterogeneous wireless networks and WLAN-3G interconnection-integration . He is currently Assistant Professor in the Department of Computer Science, Mathematics, Electronic and transportation systems (DIMET) at the University “Mediterranea” of Reggio Calabria. His mail address is ruggeri@ing.unirc.it. Domenico Tripodi received M.S. degree (cum laude) in electronic engeneering from the University ‘Mediterranea' of Reggio Calabria, Italy in 2003. He won a post-degree scholarship from CNIT in 2004, and he is currently at CNIT Research Unit of Reggio Calabria. His reasearch interest are in the area of QoS provisioning in Mobile Ad-Hoc Networks.     

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.     

Exploiting Mobility for Energy Efficient Data Collection in Wireless Sensor Networks

We analyze an architecture based on mobility to address the problem of energy efficient data collection in a sensor network. Our approach exploits mobile nodes present in the sensor field as forwarding agents. As a mobile node moves in close proximity to sensors, data is transferred to the mobile node for later depositing at the destination. We present an analytical model to understand the key performance metrics such as data transfer, latency to the destination, and power. Parameters for our model include: sensor buffer size, data generation rate, radio characteristics, and mobility patterns of mobile nodes. Through simulation we verify our model and show that our approach can provide substantial savings in energy as compared to the traditional ad-hoc network approach. Sushant Jain is a Ph.D. candidate in the Department of Computer Science and Engineering at the University of Washington. His research interests are in design and analysis of routing algorithms for networking systems. He received a MS in Computer Science from the University of Washington in 2001 and a B.Tech degree in Computer Science from IIT Delhi in 1999. Rahul C. Shah completed the B. Tech (Hons) degree from the Indian Institute of Technology, Kharagpur in 1999 majoring in Electronics and Electrical Communication Engineering. He is currently pursuing his Ph.D. in Electrical Engineering at the University of California, Berkeley. His research interests are in energy-efficient protocol design for wireless sensor/ad hoc networks, design methodology for protocols and next generation cellular networks. Waylon Brunette is a Research Engineer in the Department of Computer Science and Engineering at the University of Washington. His research interests include mobile and ubiquitous computing, wireless sensor networks, and personal area networks. Currently, he is engaged in collaborative work with Intel Research Seattle to develop new uses for embedded devices and RFID technologies in ubiquitous computing. He received a BS in Computer Engineering from the University of Washington in 2002. Gaetano Borriello is a Professor in the Department of Computer Science and Engineering at the University of Washington. His research interests are in embedded and ubiquitous computing, principally new hardware devices that integrate seamlessly into the user’s environment with particular focus on location and identification systems. His principal projects are in creating manageable RFID systems that are sensitive to user privacy concerns and in context-awareness through sensors distributed in the environment as well as carried by users. Sumit Roy received the B. Tech. degree from the Indian Institute of Technology (Kanpur) in 1983, and the M. S. and Ph. D. degrees from the University of California (Santa Barbara), all in Electrical Engineering in 1985 and 1988 respectively, as well as an M. A. in Statistics and Applied Probability in 1988. His previous academic appointments were at the Moore School of Electrical Engineering, University of Pennsylvania, and at the University of Texas, San Antonio. He is presently Prof, of Electrical Engineering, Univ. of Washington where his research interests center around analysis/design of communication systems/networks, with a topical emphasis on next generation mobile/wireless networks. He is currently on academic leave at Intel Wireless Technology Lab working on high speed UWB radios and next generation Wireless LANs. His activities for the IEEE Communications Society includes membership of several technical committees and TPC for conferences, and he serves as an Editor for the IEEE Transactions on Wireless Communications.     

Delay Analysis of Packet Scheduling with Multi-Users Diversity in Wireless CDMA Systems

There have been a number of studies that investigate efficient packet scheduling schemes to support quality of service of multiple real-time data users and to increase capacity of non-real-time users sharing a wireless channel. We consider the problem of scheduling transmissions of multiple data users sharing the same wireless channel so as to satisfy delay or throughput and present a general packet scheduling, called MBCS (Multi-users Best Channel Scheduling) which takes advantage of the multi-user diversity of a mobile wireless system. In this paper, a queuing model that represents radio resource management for supporting packet data services is developed for the purpose of evaluating the performance of wireless CDMA systems. Numerical results show that delay performance of the proposed scheduler is higher than that of the Single-user Best Channel Scheduler (SBCS) depending on the time-varying channel status.Sungkyung Kim is a Ph. D. student in the collage of information & Communications at University of Korea, Seoul, Korea. She received her B.S. and M.S. degree in electrical engineering from Korea University in 1999 and in 2001, respectively. From March 2001 to August 2004, she worked at the Electronics Telecommunications Research Institute, Daejeon, Korea, as a member of research engineer. Her research interests include MAC protocol, radio resource control, packet scheduling, and system performance evaluation at system level in wireless access networks.Chung Gu Kang received his B.S. degree in Electrical Engineering from the University of California, San Diego in 1987 and his M.S. and Ph.D. degrees both in Electrical and Computer Engineering from the University of California, Irvine, in 1989 and 1993, respectively. While working on his Ph.D. dissertation from June 1991 to May 1992, he also was with the Aerospace Corporation in El Segundo, California, as a part-time member of technical staff (MTS). After graduation in 1993, he joined Rockwell International in Anaheim, California, where he has been working on the signaling system no. 7 and other telecommunication systems development. Since March 1994, he has been with College of Information & Communications at the Korea University, Seoul, Republic of Korea, as a full professor. His research interests include next generation mobile radio communication system and broadband wireless networks, with special emphasis on physical layer/medium access control layer design and performance analysis. During the academic year of 2000, he has been a visiting scholar at Center for Wireless Communication and also a visiting professor at Department of Electrical & Computer Engineering in University of California at San Diego (UCSD). He is a member of IEEE COMSOC, IT, and VT, and a member of KICS and KITE.