Effective capacity channel model for frequency-selective fading channels

To efficiently support quality of service (QoS) in future wireless networks, it is important to model a wireless channel in terms of connection-level QoS metrics such as data rate, delay and delay-violation probability. To achieve this, in [7], we proposed and developed a link-layer channel model termed effective capacity (EC) for flat fading channels. In this paper, we apply the effective capacity technique to modeling frequency selective fading channels. Specifically, we utilize the duality between the distribution of a queue with superposition of N i.i.d. sources, and the distribution of a queue with a frequency-selective fading channel that consists of N i.i.d. sub-channels, to model a frequency selective fading channel. In the proposed model, a frequency selective fading channel is modeled by three EC functions; we also propose a simple and efficient algorithm to estimate these EC functions. Simulation results show that the actual QoS metric is closely approximated by the QoS metric predicted by the proposed EC channel model. The accuracy of the prediction using our model can translate into efficiency in admission control and resource reservation. 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 30 conferences. He is Vice Chair of Mobile and wireless multimedia Interest Group (MobIG), Technical Committee on Multimedia Communications, IEEE Communications Society. He is a member of the Best Paper Award Committee, Technical Committee on Multimedia Communications, IEEE Communications Society. 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 Associate Professor. His research interests include signal processing, coding for communications systems, information theory, networking, cross-layer optimization and sensor networks.     

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

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

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-driven asynchronous uplink subchannel allocation algorithms for space-time OFDM-CDMA systems in wireless networks

In order to support the diverse Quality of Service (QoS) requirements for differentiated data applications in broadband wireless networks, advanced techniques such as space-time coding (STC) and orthogonal frequency division multiplexing (OFDM) are implemented at the physical layer. However, the employment of such techniques evidently affects the subchannel-allocation algorithms at the medium access control (MAC) layer. In this paper, we propose the QoS-driven cross-layer subchannel-allocation algorithms for data transmissions over asynchronous uplink space-time OFDM-CDMA wireless networks. We mainly focus on QoS requirements of maximizing the best-effort throughput and proportional bandwidth fairness, while minimizing the upper-bound of scheduling delay. Our extensive simulations show that the proposed infrastructure and algorithms can achieve high bandwidth fairness and system throughput while reducing scheduling delay over wireless networks. Xi Zhang (S’89-SM’98) received the B.S. and M.S. degrees from Xidian University, Xi’an, China, the M.S. degree from Lehigh University, Bethlehem, PA, all in electrical engineering and computer science, and the Ph.D. degree in electrical engineering and computer science (Electrical Engineering—Systems) from The University of Michigan, Ann Arbor, USA. He is currently an Assistant Professor and the Founding Director of the Networking and Information Systems Laboratory, Department of Electrical and Computer Engineering, Texas A&M University, College Station, Texas, USA. He was an Assistant Professor and the Founding Director of the Division of Computer Systems Engineering, Department of Electrical Engineering and Computer Science, Beijing Information Technology Engineering Institute, Beijing, China, from 1984 to 1989. He was a Research Fellow with the School of Electrical Engineering, University of Technology, Sydney, Australia, and the Department of Electrical and Computer Engineering, James Cook University, Queensland, Australia, under a Fellowship from the Chinese National Commission of Education. He worked as a Summer Intern with the Networks and Distributed Systems Research Department, Bell Laboratories, Murray Hills, NJ, and with AT&T Laboratories Research, Florham Park, NJ, in 1997. He has published more than 80 technical papers. His current research interests focus on the areas of wireless networks and communications, mobile computing, cross-layer designs and optimizations for QoS guarantees over mobile wireless networks, wireless sensor and Ad Hoc networks, wireless and wireline network security, network protocols design and modeling for QoS guarantees over multicast (and unicast) wireless (and wireline) networks, statistical communications theory, random signal processing, and distributed computer-control systems. Dr. Zhang received the U.S. National Science Foundation CAREER Award in 2004 for his research in the areas of mobile wireless and multicast networking and systems. He is currently serving as an Editor for the IEEE Transactions on Wireless Communications, an Associated Editor for the IEEE Transactions on Vehicular Technology, and and Associated Editor for the IEEE Communications Letters, and is also currently serving as a Guest Editor for the IEEE Wireless Communications Magazine for the Special Issues of “Next Generation of CDMA vs. OFDMA for 4G Wireless Applications”. He has served or is serving as the Panelist on the U.S. National Science Foundation Research-Proposal Review Panel in 2004, the WiFi-Hotspots/WLAN and QoS Panelist at the IEEE QShine 2004, as the Symposium Chair for the IEEE International Cross-Layer Designs and Protocols Symposium within the IEEE International Wireless Communications and Mobile Computing Conference (IWCMC) 2006, the Technical Program Committee Co-Chair for the IEEE IWCMC 2006, the Poster Chair for the IEEE QShine 2006, the Publicity Co-Chair for the IEEE WirelessCom 2005, and as the Technical Program Committee members for IEEE GLOBECOM, IEEE ICC, IEEE WCNC, IEEE VTC, IEEE QShine, IEEE WoWMoM, IEEE WirelessCom, and IEEE EIT. He is a Senior Member of the IEEE and a member of the Association for Computing Machinery (ACM). Jia Tang (S’03) received the B.S. degree in electrical engineering from Xi’an Jiaotong University, Xi’an, China, in 2001. He is currently a Research Assistant working towards the Ph.D. degree in the Networking and Information Systems Laboratory, Department of Electrical and Computer Engineering, Texas A&M University, College Station, Texas, USA. His research interests include mobile wireless communications and networks, with emphasis on cross-layer design and optimizations, wireless quality-of-service (QoS) provisioning for mobile multimedia networks, wireless diversity techniques, and wireless resource allocation. Mr. Tang received the Fouraker Graduate Research Fellowship Award from the Department of Electrical and Computer Engineering, Texas A&M University in 2005.     

Cross-layer modeling of adaptive wireless links for QoS support in heterogeneous wired-wireless networks

Future wired-wireless multimedia networks require diverse quality-of-service (QoS) support. To this end, it is essential to rely on QoS metrics pertinent to wireless links. In this paper, we develop a cross-layer model for adaptive wireless links, which enables derivation of the desired QoS metrics analytically from the typical wireless parameters across the hardware-radio layer, the physical layer and the data link layer. We illustrate the advantages of our model: generality, simplicity, scalability and backward compatibility. Finally, we outline its applications to power control, TCP, UDP and bandwidth scheduling in wireless networks. The work by Q. Liu and G. B. Giannakis are prepared through collaborative participation in the Communications and Networks Consortium sponsored by the U.S. Army Research Laboratory under the Collaborative Technology Alliance Program, Cooperative Agreement DAAD19-01-2-0011. The U.S. Government is authorized to reproduce and distribute reprints for Government purposes notwithstanding any copyright notation thereon. The work by S. Zhou is supported by UConn Research Foundation internal grant 445157. Qingwen Liu (S’04) received the B.S. degree in electrical engineering and information science in 2001, from the University of Science and Technology of China (USTC). He received the M.S. degree in electrical engineering in 2003, from the University of Minnesota (UMN). He currently pursues his Ph.D. degree in the Department of Electrical and Computer Engineering at the University of Minnesota (UMN). His research interests lie in the areas of communications, signal processing, and networking, with emphasis on cross-layer analysis and design, quality of service support for multimedia applications over wired-wireless networks, and resource allocation. Shengli Zhou (M’03) received the B.S. degree in 1995 and the M.Sc. degree in 1998, from the University of Science and Technology of China (USTC), both in electrical engineering and information science. He received his Ph.D. degree in electrical engineering from the University of Minnesota, 2002, and joined the Department of Electrical and Computer Engineering at the University of Connecticut, 2003. His research interests lie in the areas of communications and signal processing, including channel estimation and equalization, multi-user and multi-carrier communications, space time coding, adaptive modulation, and cross-layer designs. He serves as an associate editor for IEEE Transactions on Wireless Communications since Feb. 2005. G. B. Giannakis (Fellow’97) received his Diploma in Electrical Engineering from the National Technical University of Athens, Greece, 1981. From September 1982 to July 1986 he was with the University of Southern California (USC), where he received his MSc. in Electrical Engineering, 1983, MSc. in Mathematics, 1986, and Ph.D. in Electrical Engineering, 1986. After lecturing for one year at USC, he joined the University of Virginia in 1987, where he became a professor of Electrical Engineering in 1997. Since 1999 he has been a professor with the Department of Electrical and Computer Engineering at the University of Minnesota, where he now holds an ADC Chair in Wireless Telecommunications. His general interests span the areas of communications and signal processing, estimation and detection theory, time-series analysis, and system identification -- subjects on which he has published more than 200 journal papers, 350 conference papers and two edited books. Current research focuses on transmitter and receiver diversity techniques for single- and multi-user fading communication channels, complex-field and space-time coding, multicarrier, ultra-wide band wireless communication systems, cross-layer designs and sensor networks. G. B. Giannakis is the (co-) recipient of six paper awards from the IEEE Signal Processing (SP) and Communications Societies (1992, 1998, 2000, 2001, 2003, 2004). He also received the SP Society’s Technical Achievement Award in 2000. He served as Editor in Chief for the IEEE SP Letters, as Associate Editor for the IEEE Trans. on Signal Proc. and the IEEE SP Letters, as secretary of the SP Conference Board, as member of the SP Publications Board, as member and vice-chair of the Statistical Signal and Array Processing Technical Committee, as chair of the SP for Communications Technical Committee and as a member of the IEEE Fellows Election Committee. He has also served as a member of the IEEE-SP Society’s Board of Governors, the Editorial Board for the Proceedings of the IEEE and the steering committee of the IEEE Trans. on Wireless Communications.     

Multiconstrained QoS multipath routing in wireless sensor networks

Sensor nodes are densely deployed to accomplish various applications because of the inexpensive cost and small size. Depending on different applications, the traffic in the wireless sensor networks may be mixed with time-sensitive packets and reliability-demanding packets. Therefore, QoS routing is an important issue in wireless sensor networks. Our goal is to provide soft-QoS to different packets as path information is not readily available in wireless networks. In this paper, we utilize the multiple paths between the source and sink pairs for QoS provisioning. Unlike E2E QoS schemes, soft-QoS mapped into links on a path is provided based on local link state information. By the estimation and approximation of path quality, traditional NP-complete QoS problem can be transformed to a modest problem. The idea is to formulate the optimization problem as a probabilistic programming, then based on some approximation technique, we convert it into a deterministic linear programming, which is much easier and convenient to solve. More importantly, the resulting solution is also one to the original probabilistic programming. Simulation results demonstrate the effectiveness of our approach. This work was supported in part by the U.S. National Science Foundation under grant DBI-0529012, the National Science Foundation Faculty Early Career Development Award under grant ANI-0093241 and the Office of Naval Research under Young Investigator Award N000140210464. Xiaoxia Huang received her BS and MS in the Electrical Engineering from Huazhong University of Science and Technology in 2000 and 2002, respectively. She is completing her Ph.D. degree in the Department of Electrical and Computer Engineering at the University of Florida. Her research interests include mobile computing, QoS and routing in wireless ad hoc networks and wireless sensor networks. Yuguang Fang received a Ph.D. degree in Systems Engineering from Case Western Reserve University in January 1994 and a Ph.D degree in Electrical Engineering from Boston University in May 1997. He was an assistant professor in the Department of Electrical and Computer Engineering at New Jersey Institute of Technology from July 1998 to May 2000. He then joined the Department of Electrical and Computer Engineering at University of Florida in May 2000 as an assistant professor, got an early promotion to an associate professor with tenure in August 2003 and to a full professor in August 2005. He holds a University of Florida Research Foundation (UFRF) Professorship from 2006 to 2009. He has published over 200 papers in refereed professional journals and conferences. He received the National Science Foundation Faculty Early Career Award in 2001 and the Office of Naval Research Young Investigator Award in 2002. He has served on several editorial boards of technical journals including IEEE Transactions on Communications, IEEE Transactions on Wireless Communications, IEEE Transactions on Mobile Computing and ACM Wireless Networks. He have also been activitely participating in professional conference organizations such as serving as The Steering Committee Co-Chair for QShine, the Technical Program Vice-Chair for IEEE INFOCOM’2005, Technical Program Symposium Co-Chair for IEEE Globecom’2004, and a member of Technical Program Committee for IEEE INFOCOM (1998, 2000, 2003–2007).     

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).     

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).     

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.     

A secure incentive protocol for mobile ad hoc networks

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

A call admission and rate control scheme for multimedia support over IEEE 802.11 wireless LANs

Quality of service (QoS) support for multimedia services in the IEEE 802.11 wireless LAN is an important issue for such WLANs to become a viable wireless access to the Internet. In this paper, we endeavor to propose a practical scheme to achieve this goal without changing the channel access mechanism. To this end, a novel call admission and rate control (CARC) scheme is proposed. The key idea of this scheme is to regulate the arriving traffic of the WLAN such that the network can work at an optimal point. We first show that the channel busyness ratio is a good indicator of the network status in the sense that it is easy to obtain and can accurately and timely represent channel utilization. Then we propose two algorithms based on the channel busyness ratio. The call admission control algorithm is used to regulate the admission of real-time or streaming traffic and the rate control algorithm to control the transmission rate of best effort traffic. As a result, the real-time or streaming traffic is supported with statistical QoS guarantees and the best effort traffic can fully utilize the residual channel capacity left by the real-time and streaming traffic. In addition, the rate control algorithm itself provides a solution that could be used above the media access mechanism to approach the maximal theoretical channel utilization. A comprehensive simulation study in ns-2 has verified the performance of our proposed CARC scheme, showing that the original 802.11 DCF protocol can statically support strict QoS requirements, such as those required by voice over IP or streaming video, and at the same time, achieve a high channel utilization. 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 PhD degree in the Department of Electrical and Computer Engineering, University of Florida. He is a student member of IEEE. 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, and the Ph.D. degree in electrical and computer engineering from the University of Florida, Gainesville, in 2005. He is currently a Senior Research Engineer at Motorola Labs, Arlington Heights, IL. His research interests include resource management, medium access control, and quality of service (QoS) in wireless networks. He is a Member of Tau Beta Pi and 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 with tenure in August 2003 and has been an Associate Professor since then. He has published over one hundred (100) 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).     

Harnessing Traffic Uncertainties in Wireless Mesh Networks—A Stochastic Optimization Approach

In this paper, we investigate the routing optimization problem in wireless mesh networks. While existing works usually assume static and known traffic demand, we emphasize that the actual traffic is time-varying and difficult to measure. In light of this, we alternatively pursue a stochastic optimization framework where the expected network utility is maximized. For multi-path routing scenario, we propose a stochastic programming approach which requires no priori knowledge on the probabilistic distribution of the traffic. For the single-path routing counterpart, we develop a learning-based algorithm which provably converges to the global optimum solution asymptotically.

Medium Access Control for Integrated Multimedia Wireless Access with the Use of a Video Packet Discard Scheme

A well designed Medium Access Control (MAC) protocol for wireless networks should provide an efficient mechanism to share the limited bandwidth resources, and satisfy the diverse and usually contradictory Quality of Service (QoS) requirements of each traffic class. In this paper a new MAC protocol for next generation wireless communications is presented and investigated. The protocol uses a combined Packet Discard/Forward Error Correction scheme in order to efficiently integrate MPEG-4 videoconference packet traffic with voice, SMS data and web packet traffic over a noisy wireless channel of high capacity. Our scheme achieves high aggregate channel throughput in all cases of traffic load, while preserving the Quality of Service (QoS) requirements of each traffic type, and is shown to clearly outperform DPRMA, another efficient MAC protocol proposed in the literature for multimedia traffic integration over wireless networks. Dr. Polychronis Koutsakis was born in Hania, Greece, in 1974. He received his 5-year Diploma in Electrical Engineering in 1997 from the University of Patras, Greece and his MSc and Ph.D. degrees in Electronic and Computer Engineering in 1999 and 2002, respectively, from the Technical University of Crete, Greece. He was a Visiting Lecturer at the Electronic and Computer Engineering Department of the same University for three years (2003–2006). He is currently an Assistant Professor at the Electrical and Computer Engineering Department of McMaster University, Canada. His research interests focus on the design, modeling and performance evaluation of computer communication networks, and especially on the design and evaluation of multiple access schemes for multimedia integration over wireless networks, on call admission control and traffic policing schemes for both wireless and wired networks, on multiple access control protocols for mobile satellite networks, wireless sensor networks and powerline networks, and on traffic modeling. Dr. Koutsakis has authored more than 45 peer-reviewed papers in the above mentioned areas, has served as a Guest Editor for an issue of the ACM Mobile Computing and Communications Review, as a TPC member for conferences such as IEEE GLOBECOM, IEEE LCN and IEEE PerCom, will serve as Session Chair for the IEEE GLOBECOM 2006 Symposium on Satellite & Space Communications and serves as a reviewer for most of the major journal publications focused on his research field. Moisis Vafiadis was born in Elefsina, Greece, in 1980. He has recently completed his studies towards the Diploma in Electronic Engineering at the Technological Educational Institute of Crete, Greece. His research interests focus on wireless personal communication networks, and especially on the MAC layer and on the development and testing of wireless multimedia applications.     

Design and Evaluation of a QoS-aware Framework for HIPERLAN/2 Networks

Recent advances on wireless technology are enabling the design and deployment of multiservice wireless networks. In order to be able to meet the QoS requirements of the various applications, it is essential to deploy QoS provisioning mechanisms. In this paper, we present a QoS framework to support various types of services in a wireless networking environment. Under this QoS framework, we propose various resource request mechanisms. We carry out a comparative study of the proposed schemes. Our simulation results show the effectiveness of the mechanisms when supporting different services, such as video, voice, best-effort and background traffic. Francisco M. Delicado This author received his M.Sc. degree in Physics (Electronics and Computer Science) from the University Complutense of Madrid, Madrid, Spain in 1995. He is currently a Ph.D. degree student in the Department of Computer Engineering at the University of Castilla-La Mancha. His research interests include high-performance networks, specially wireless LAN, QoS over WLAN, video compression, video transmission and error-resilient protocol architectures. Pedro Cuenca This author received his M.Sc. degree in Physics (Electronics and Computer Science, award extraordinary) from the University of Valencia in 1994. He got his Ph.D. degree in Computer Engineering in 1999 from the Polytechnic University of Valencia, Spain. In 1995 he joined the Department de Computer Engineering at the University of Castilla-La Mancha. He is currently an Associate Professor of Communications and Computer Networks. He has also been a visiting researcher at The Nottingham Trent University, Nottingham (England) and at the Multimedia Communications Research Laboratory, University of Ottawa (Canada). His research topics are centered in the area of high-performance networks, wireless LAN, video compression, QoS video transmission and error-resilient protocol architectures. He has served in the organization of International Conferences as Session Chair. He has been reviewer for several Journals and for several International Conferences. He is a member of the IFIP 6.8 Working Group and a member of the IEEE. Luis Orozco-Barbosa This author received the B.Sc. degree in electrical and computer engineering from Universidad Autonoma Metropolitana, Mexico, in 1979, the Diplome d'Etudes Approfondies from ENSIMAG, France, in 1984 and the Doctorat de l'Universite from Universite Pierre et Marie Curie, France, in 1987, both in computer science. From 1991 to 2002, he was a Faculty Member of Computer Engineering at the School of Information Technology and Engineering (SITE), University of Ottawa, Canada. In 2002, he joined the Department of Computer Engineering at Universidad de Castilla La Mancha (SPAIN) where he is currently Director of the Albacete Research Institute of Informatics. He has published over 180 papers in international Journals and Conferences on computer networks and performance evaluation. His current research interests include Internet protocols, video communications, wireless networks, traffic modeling and performance evaluation. He is a member of the IEEE. Antonio Garrido This author received the degree in physics (electronics and computer science) and the Ph.D. degrees from the University of Granada, Spain, in 1986 and University of Valencia, Spain, in 1991, respectively. In 1986, he joined the Department of Computer Engineering at the University of Castilla-La Mancha, where he is currently a Full Professor of Computer Architecture and Technology and Dean of the EscuelaPolitecnica Superior de Albacete (School of Computer Engineering). His research interests include high-performance networks, telemedicine, video compression, and video transmission. He has published over 40 papers in international journals conferences on performance evaluation of parallel computer and communications systems and compression and transmission in high-speed networks. He has led several research projects in telemedicine, computer networks and advanced computer system architectures.     

RObust Header Compression (ROHC) Performance for Multimedia Transmission over 3G/4G Wireless Networks

RObust Header Compression (ROHC) has recently been proposed to reduce the large protocol header overhead when transmitting voice and other continuous media over IP based protocol stacks in wireless networks. In this paper we evaluate the real-time transmission of GSM encoded voice and H.26L encoded video with ROHC over a wireless link. For the voice transmission we examine the impact of ROHC on the consumed bandwidth, the voice quality, and the delay jitter in the voice signal. We find that for a wide range of error probabilities on the wireless link, ROHC roughly cuts the bandwidth required for the transmission of GSM encoded voice in half. In addition, ROHC improves the voice quality compared to transmissions without ROHC, especially for large bit error probabilities on the wireless link. The improvement reaches 0.26 on the 5-point Mean Opinion Score for a bit error probability of 10^–3. For the video transmission we examine the impact of ROHC on the consumed bandwidth. We find that the bandwidth savings with ROHC depend on the quantization scale used for the video encoding and the video content and ranges between 5–40% for typical scenarios.Frank H.P. Fitzek is an Associate Professor in the Department of Communication Technology, University of Aalborg, Denmark heading the Future Vision group. He received his diploma (Dipl.-Ing.) degree in electrical engineering from the University of Technology – Rheinisch-Westflische Technische Hochschule (RWTH) – Aachen, Germany, in 1997 and his Ph.D. (Dr.-Ing.) in Electrical Engineering from the Technical University Berlin, Germany in 2002. 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. His current research interests are in the areas of 4G wireless communication, QoS support for multimedia services, access techniques, security for wireless communication, and the integration of multi hop networks in cellular systems. Dr. Fitzek serves on the Editorial Board of the IEEE Communications Surveys and Tutorials. He is the program chair for the International Conference on Advances in Computer Entertainment Technology (ACE2004) and serves in the program committee for VTC2003, VTC2004, ACE2004, and IEEE MWN2004.Stephan Rein studied Electrical Engineering at the Technical University of Aachen, Germany, and the Technical University of Berlin (TUB), Germany. He received the Dipl.-Ing. degree in electrical engineering from the TUB in 2003. From March 2003 to October 2003 he visited the multimedia networking group in the Department of Electrical Engineering at Arizona State University, Tempe. He is currently pursuing the Ph.D. degree at the Institute for Energy and Automation Technology, Technical University of Berlin. His current research interests include data compression and digital signal processing with emphasis on wavelet theory.Patrick Seeling received the Dipl.-Ing. degree in industrial engineering and management (specializing in electrical engineering) from the Technical University of Berlin (TUB), Germany, in 2002. Since 2003 he has been a Ph.D. student in the Department of Electrical Engineering at Arizona State University. His research interests are in the area of video communications in wired and wireless networks. He is a student member of the IEEE and the ACM.Martin Reisslein is an Assistant Professor in the Department of Electrical Engineering at Arizona State University, 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. While in Berlin he was teaching courses on performance evaluation and computer networking at the Technical University Berlin. 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 . 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, and optical networking.     

Energy-aware on-demand routing protocols for wireless ad hoc networks

Energy use is a crucial design concern in wireless ad hoc networks since wireless terminals are typically battery-operated. The design objectives of energy-aware routing are two folds: Selecting energy-efficient paths and minimizing the protocol overhead incurred for acquiring such paths. To achieve these goals simultaneously, we present the design of several on-demand energy-aware routing protocols. The key idea behind our design is to adaptively select the subset of nodes that are required to involve in a route-searching process in order to acquire a high residual-energy path and/or the degree to which nodes are required to participate in the process of searching for a low-power path in networks wherein nodes have transmission power adjusting capability. Analytical and simulation results are given to demonstrate the high performance of the designed protocols in energy-efficient utilization as well as in reducing the protocol overhead incurred in acquiring energy-efficient routes. Baoxian Zhang received his B.S., M.S., and Ph.D. degrees in Electrical Engineering from Northern Jiaotong University, Beijing, China in 1994, 1997, and 2000, respectively. From January 2001 to August 2002, he was working with Department of Electrical and Computer Engineering at Queen’s University in Kingston as a postdoctoral fellow. He is currently a research scientist with the School of Information Technology and Engineering (SITE) of University of Ottawa in Ottawa, Ontario, Canada. He has published over 40 refereed technical papers in international journals and conference proceedings. His research interests include routing algorithm and protocol design, QoS management, wireless ad hoc and sensor networks, survivable optical networks, multicast communications, and performance evaluation. He is a member of the IEEE. Hussein Mouftah joined the School of Information Technology and Engineering (SITE) of the University of Ottawa in September 2002 as a Canada Research Chair (Tier 1) Professor in Optical Networks. He has been with the Department of Electrical and Computer Engineering at Queen’s University (1979-2002), where he was prior to his departure a Full Professor and the Department Associate Head. He has three years of industrial experience mainly at Bell Northern Research of Ottawa, now Nortel Networks (1977-79). He has spent three sabbatical years also at Nortel Networks (1986-87, 1993-94, and 2000-01), always conducting research in the area of broadband packet switching networks, mobile wireless networks and quality of service over the optical Internet. He served as Editor-in-Chief of the IEEE Communications Magazine (1995-97) and IEEE Communications Society Director of Magazines (1998-99) and Chair of the Awards Committee (2002-2003). He is a Distinguished Speaker of the IEEE Communications Society since 2000. Dr. Mouftah is the author or coauthor of five books, 22 book chapters and more than 700 technical papers and 8 patents in this area. He is the recipient of the 1989 Engineering Medal for Research and Development of the Association of Professional Engineers of Ontario (PEO), and the Ontario Distinguished Researcher Award of the Ontario Innovation Trust. He is the joint holder of the Best Paper Award for a paper presented at SPECTS’2002, and the Outstanding Paper Award for papers presented at the IEEE HPSR’2002 and the IEEE ISMVL’1985. Also he is the joint holder of a Honorable Mention for the Frederick W. Ellersick Price Paper Award for Best Paper in the IEEE Communications Magazine in 1993. He is the recipient of the IEEE Canada (Region 7) Outstanding Service Award (1995). Also he is the recipient of the 2004 IEEE Communications Society Edwin Howard Armstrong Achievement Award, and the 2004 George S. Glinski Award for Excellence in Research of the Faculty of Engineering, University of Ottawa. Dr. Mouftah is a Fellow of the IEEE (1990) and Fellow of the Canadian Academy of Engineering (2003).     

An efficient and flexible MPLS signaling framework for mobile networks

Multiprotocol Label Switching (MPLS) has gained momentum in recent years as an effective tool to provide Quality of Service (QoS) in a variety of networks. This has in turn created active interest in the area of recovery in MPLS based networks. A number of recovery schemes for MPLS domains have been proposed in recent years. However, the current schemes lack support for recovery in dynamic network topologies. In this paper, a new flexible signaling protocol for LSP rerouting in dynamic network environments is introduced. The signaling protocol recovers from node and link failures reactively, taking a local approach to LSP reestablishment. The performance of the signaling protocol is evaluated through simulations. Results indicate that the protocol can effectively and efficiently handle rerouting in dynamic networks with a low protocol signaling overhead as compared to contemporary MPLS rerouting protocols. This would enable the MPLS based IP-QoS support mechanisms to extend to dynamic network topologies. A preliminary version of this work was presented at the 2004 IEEE International Conference on Communications, Paris. Ramprasad Nagarajan has received his B.E. degree in Electronics and Telecommunications from Pune University, India in 1999. He received his M.S. degree in Electrical and Computer Engineering from the Ohio State University, Columbus, OH in 2004. Currently, he is a Wireless Network Engineer in Nortel Networks, specializing in the area of network architecture and design of wireless packet core networks. Ramprasad’s current research interests include the study of wireless network evolution trends, next generation wireless networks, network capacity planning, performance analysis, and optimization. He is a member of the IEEE. Eylem Ekici has received his B.S. and M.S. degrees in Computer Engineering from Bogazici University, Istanbul, Turkey, in 1997 and 1998, respectively. He received his Ph.D. degree in Electrical and Computer Engineering from Georgia Institute of Technology, Atlanta, GA, in 2002. Currently, he is an assistant professor in the Department of Electrical and Computer Engineering of the Ohio State University, Columbus, OH. Dr. Ekici’s current research interests include wireless sensor networks, vehicular communication systems, next generation wireless systems, and space-based networks, with a focus on routing and medium access control protocols, resource management, and analysis of network architectures and protocols. He also conducts research on interfacing of dissimilar networks.     

Channel Sharing Scheme for Packet-Switched Cellular Networks

In this paper, we study an approach for sharing channels to improve network utilization in packet-switched cellular networks. Our scheme exploits unused resources in neighboring cells without the need for global coordination. We formulate a minimax approach to optimizing the allocation of channels in this sharing scheme. We develop a measurement-based distributed algorithm to achieve this objective and study its convergence. We illustrate, via simulation results, that the distributed channel sharing scheme performs significantly better than the fixed channel scheme over a wide variety of traffic conditions. This research was supported in part by the National Science Foundation through grants ECS-0098089, ANI-0099137, ANI-0207892, ANI-9805441, ANI-0099137, and ANI-0207728, and by an Indiana 21st century grant. A conference version of this paper appeared in INFOCOM 99. This work was done when all the authors were at Purdue University. Suresh Kalyanasundaram received his Bachelors degree in Electrical and Electronics Engineering and Masters degree in Physics from Birla Institute of Technology and Science, Pilani, India in 1996. He received his Ph.D. from the School of Electrical and Computer Engineering, Purdue University, in May 2000. Since then he has been with Motorola, working in the area of performance analysis of wireless networks. Junyi Li received his B.S. and M.S. degrees from Shanghai Jiao Tong University, and Ph.D. degree from Purdue University. He was with the Department of Digital Communications Research at Bell Labs, Lucent Technologies from 1998 to 2000. In 2000 as a founding member he jointed Flarion Technologies, where he is now Director of Technology. He is a senior member of IEEE. Edwin K.P. Chong received the B.E.(Hons.) degree with First Class Honors from the University of Adelaide, South Australia, in 1987; and the M.A. and Ph.D. degrees in 1989 and 1991, respectively, both from Princeton University, where he held an IBM Fellowship. He joined the School of Electrical and Computer Engineering at Purdue University in 1991, where he was named a University Faculty Scholar in 1999, and was promoted to Professor in 2001. Since August 2001, he has been a Professor of Electrical and Computer Engineering and a Professor of Mathematics at Colorado State University. His current interests are in communication networks and optimization methods. He coauthored the recent book, An Introduction to Optimization, 2nd Edition, Wiley-Interscience, 2001. He was on the editorial board of the IEEE Transactions on Automatic Control, and is currently an editor for Computer Networks. He is an IEEE Control Systems Society Distinguished Lecturer. He received the NSF CAREER Award in 1995 and the ASEE Frederick Emmons Terman Award in 1998. Ness B. Shroff received his Ph.D. degree from Columbia University, NY in 1994. He is currently an Associate Professor in the School of Electrical and Computer Engineering at Purdue University. His research interests span the areas of wireless and wireline communication networks. He is especially interested in fundamental problems in the design, performance, scheduling, capacity, pricing, and control of these networks. His research is funded by various companies such as Intel, Hewlett Packard, Nortel, AT&T, and L. G. Electronics; and government agencies such as the National Science Foundation, Indiana Dept. of Transportation, and the Indiana 21st Century fund. Dr. Shroff is an editor for IEEE/ACM Trans. on Networking and the Computer Networks Journal, and past editor of IEEE Communications Letters. He was the conference chair for the 14th Annual IEEE Computer Communications Workshop (in Estes Park, CO, October 1999) and program co-chair for the symposium on high-speed networks, Globecom 2001 (San Francisco, CA, November 2000). He is also the Technical Program co-chair for IEEE INFOCOM'03 and panel co-chair for ACM Mobicom'02. He received the NSF CAREER award in 1996.     

Scalable Multiple Channel Scheduling with Optimal Utility in Wireless Local Area Networks

This paper studies scheduling algorithms for an infra-structure based wireless local area network with multiple simultaneous transmission channels. A reservation-based medium access control protocol is assumed where the base station (BS) allocates transmission slots to the system mobile stations based on their requests. Each station is assumed to have a tunable transmitter and tunable receiver. For this network architecture, the scheduling algorithms can be classified into two categories: contiguous and non-contiguous, depending on whether slots are allocated contiguously to the mobile stations. The main objective of the scheduling algorithms is to achieve high channel utility while having low time complexity. In this paper, we propose three scheduling algorithms termed contiguous sorted sequential allocation (CSSA), non-contiguous round robin allocation (NCRRA) and non-contiguous sorted round robin allocation (NCSRRA). Among these, CSSA schedules each station in contiguous mode, while other two algorithms, NCRRA and NCSRRA, schedule stations in non-contiguous mode. Through extensive analysis and simulation, the results demonstrate that the CSSA with only slightly increased complexity can achieve much higher channel utility when compared to the existing contiguous scheduling algorithms. The NCRRA and NCSRRA on the other hand, results in significantly lower complexity, while still achieving the optimal channel utility compared to existing non-contiguous scheduling algorithms. Chonggang Wang received a B.Sc. (honors) degree from Northwestern Polytechnic University, Xi'an, China, in 1996, and M.S. and Ph. D. degrees in communication and information system from University of Electrical Science and Technology in China, Chengdu, China, and Beijing University of Posts and Telecommunications, Beijing, China, in 1999 and 2002, respectively. From September 2002 to November 2003 he has been with the Hong Kong University of Science and Technology, Hong Kong, where he is an associate researcher in the Department of Computer Science. He is now a post-doctoral research fellow in University of Arkansas, Arkansas. His current research interests are in wireless networks with QoS guarantee, sensor networks, peer-to-peer and overlay networks. Bo Li received the B.S. (summa cum laude) and M.S. degrees in the Computer Science from Tsinghua University, Beijing, P. R. China, in 1987 and 1989, respectively, and the Ph.D. degree in the Electrical and Computer Engineering from University of Massachusetts at Amherst in 1993. Between 1994 and 1996, he worked on high performance routers and ATM switches in IBM Networking System Division, Research Triangle Park, North Carolina. Since January 1996, he has been with Computer Science Department, the Hong Kong University of Science and Technology, where he is an associated professor and co-director for the ATM/IP cooperate research center, a government sponsored research center. Since 1999, he has also held an adjunct researcher position at the Microsoft Research Asia (MSRA), Beijing, China. His current research interests include wireless mobile networking supporting multimedia, video multicast and all optical networks using WDM, in which he has published over 150 technical papers in referred journals and conference proceedings. He has been an editor or a guest editor for 16 journals, and involved in the organization of about 40 conferences. He was the Co-TPC Chair for IEEE Infocom'2004. He is a member of ACM and a senior member of IEEE. Krishna M. Sivalingam (ACM ‘93) 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 M.S. and Ph.D. degrees in Computer Science from State University of New York at Buffalo in 1990 and 1994 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 twenty-five journal publications. He has published an edited book on Wireless Sensor Networks in 2004 and on optical networks in 2000 and in 2004. He is a member of the Editorial Board for ACM Wireless Networks Journal, IEEE Transactions on Mobile Computing, and KICS Journal of Computer Networks. He has served as a Guest Co-Editor for special issues of ACM MONET on “Wireless Sensor Networks” in 2003 and 2004 and an issue of 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, and KICS Journal of Computer Networks. He is serving as Technical Program Co-Chair for the First IEEE Conference on Sensor Communications and Networking to be held in Santa Clara, CA in 2004. He has served as General Co-Chair for SPIE Opticomm 2003 (Dallas, TX) and for ACM Intl. Workshop on Wireless Sensor Networks and Applications (WSNA) 2003 held on conjunction with ACM MobiCom 2003 at San Diego, CA. He served 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. Kazem Sohraby received the BS, MS and PhD degrees in electrical engineering and the MBA from the Wharton School, University of Pennsylvania, Philadephia. He is a Professor of the Electrical Engineering Department, College of Engineering, University of Arkansas, Fayetteville. Prior to that, he was with Bell Laboratories, Holmdel, NJ. His areas of interest include computer networking, signaling, switching, performance analysis, and traffic theory. He has over 20 applications and granted patents on computer protocols, wireless and optical systems, circuit and packet switching, and on optical Internet. He has several publications, including a book on The Performance and Control of Computer Communications Networks (Boston, MA: 1995). Dr Sohraby is a Distinguished Lecturer of the IEEE Communications Society, and serves as its President's representative on the Committee on Communications and Information Policy (CCIP). He served on the Education Committee of the IEEE Communications Society, is on the Editorial Boards of several publications, and served as Reviewer and Panelist with the National Science Foundation, the US Army and the Natural Sciences and Engineering Research Council of Canada.