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.     

Statistically assisted routing algorithms (SARA) for hop count based forwarding in wireless sensor networks

The main goal of this paper is to provide routing–table-free online algorithms for wireless sensor networks (WSNs) to select cost (e.g., node residual energies) and delay efficient paths. As basic information to drive the routing process, both node costs and hop count distances are considered. Particular emphasis is given to greedy routing schemes, due to their suitability for resource constrained and highly dynamic networks. For what concerns greedy forwarding, we present the Statistically Assisted Routing Algorithm (SARA), where forwarding decisions are driven by statistical information on the costs of the nodes within coverage and in the second order neighborhood. By analysis, we prove that an optimal online policy exists, we derive its form and we exploit it as the core of SARA. Besides greedy techniques, sub–optimal algorithms where node costs can be partially propagated through the network are also presented. These techniques are based on real time learning LRTA algorithms which, through an initial exploratory phase, converge to quasi globally optimal paths. All the proposed schemes are then compared by simulation against globally optimal solutions, discussing the involved trade–offs and possible performance gains. The results show that the exploitation of second order cost information in SARA substantially increases the goodness of the selected paths with respect to fully localized greedy routing. Finally, the path quality can be further increased by LRTA schemes, whose convergence can be considerably enhanced by properly setting real time search parameters. However, these solutions fail in highly dynamic scenarios as they are unable to adapt the search process to time varying costs. Michele Rossi was born in Ferrara, Italy on October 30th, 1974. He received the Laurea degree in Electrical Engineering (with honors) and the Ph.D. degree in Information Engineering from the University of Ferrara in 2000 and 2004, respectively. Since 2000 he has been a Research Fellow at the Department of Engineering of the University of Ferrara. During 2003 he was on leave at the Center for Wireless Communications (CWC) at the University of California San Diego (UCSD), where he did research on wireless sensor networks. In November 2005 he joined the Department of Information Engineering of the University of Padova, Italy, where he is currently an Assistant Professor. Michele Rossi is currently part of the EU funded Ambient Networks and eSENSE projects. His research interests include: TCP/IP protocols over wireless networks, performance analysis of link layer retransmission techniques, routing and access selection in heterogeneous wireless networks and MAC/routing algorithms for wireless sensor networks. Michele Zorzi was born in Venice, Italy, in 1966. He received the Laurea degree and the Ph.D. degree in Electrical Engineering from the University of Padova, Italy, in 1990 and 1994, respectively. During the Academic Year 1992/93, he was on leave at the University of California, San Diego (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, and in 2003 joined the Department of Information Engineering of the University of Padova, Italy, where he is currently a Professor. 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 from 2003 to 2005 was 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. He was also guest editor for special issues in the IEEE Personal Communications Magazine (Energy Management in Personal Communications Systems) and the IEEE Journal on Selected Areas in Communications (Multi-media Network Radios). Ramesh R. Rao was born in Sindri, India, where he completed his undergraduate work at the Regional Engineering College of the University of Madras in Tiruchirapalli, obtaining a BE (Honors) degree in Electronics and Communications in 1980. He completed his graduate work at the University of Maryland, College Park, Maryland where he received his M.S. and Ph.D. Professor Rao is currently a Professor at the University of California, San Diego (UCSD) at the department of Electrical and Computer Engineering in the Irwin and Joan Jacobs School of Engineering, where he has been a member of the faculty since 1984. Professor Rao is the former director of UCSD’s Center for Wireless Communications (CWC), and currently serves as the Qualcomm Endowed Chair in Telecommunications and Information Technologies, and as the Director of the San Diego Division of the California Institute of Telecommunications and Information Technology [Cal-(IT)²]. As Director of the San Diego Division of Cal-(IT)², he leads several interdisciplinary and collaborative projects. His research interests include architectures, protocols and performance analysis of computer and communication networks, and he has published extensively on these topics. Since 1984, Professor Rao has authored over 100 technical papers, contributed book chapters, conducted a number of short courses and delivered invited talks and plenary lectures. He is currently supervising both masters and doctoral students.     

Pre-equalization Techniques for Downlink and Uplink TDD MC-CDMA Systems

Time division duplex (TDD) multi carrier-code division multiple access (MC-CDMA) systems have recently been proposed as potential candidates for next generation (4G) technology. In order to mitigate multiple access interference, in this paper we investigate pre-equalization schemes for both downlink and uplink transmissions, the former also in a multiple transmit antenna scenario. In particular, new pre-equalizer techniques are introduced and complexity issues addressed. Numerical results are given to highlight the effectiveness of the proposed schemes with respect to other existing pre-equalizer solutions. Paola Bisaglia was born in Padova, Italy, on August 8, 1971. She received the Laurea (cum laude) and Ph.D. degrees in electronic engineering from the University of Padova, Padova, Italy in 1996 and 2000 respectively. In 2000 she joined Hewlett-Packard Research Laboratories, Bristol, England, working on Home Phoneline Networking and wireless LANs. From 2002 she is a research fellow at the Department of Information Engineering of the University of Padova, Italy. Her research interests include wireless local area networks; modulation, coding techniques and detection strategies for next generation (4G) broadband cellular systems, based on the combination of multi-carrier and spread-spectrum modulations. Luca Sanguinetti is a Ph.D. Student of the University of Pisa. He was born in Empoli, Italy, on February 19, 1977, and he received the Doctor Engineer degree (cum laude) in information engineering from the University of Pisa, Italy, in 2002. Since 2002 he was with the Department of Information Engineering of the University of Pisa, where he is working toward the Ph.D. degree in information engineering under the supervision of Prof. Umberto Mengali and Prof. Michele Morelli. In 2004, he was a visiting Ph.D. student at the German Aerospace Center (DLR), Oberpfaffenhofen, Germany. Currently he is involved in a research project dealing with the design and the development of base stations and user terminals for wideband wireless communications systems able to cope with those reconfigurability and interoperability characteristics required by the next generation mobile communication systems. His research interests are in wireless communication theory, with emphasis on synchronization and detection algorithms and channel estimation in multiple-access communication systems. Michele Morelli received the Laurea (cum laude) in electrical engineering and the “Premio di Laurea SIP” from the University of Pisa, Italy, in 1991 and 1992 respectively. From 1992 to 1995 he was with the Department of Information Engineering of the University of Pisa, where he received the Ph.D. degree in electrical engineering. In September 1996 he joined the Centro Studi Metodi e Dispositivi per Radiotrasmissioni (CSMDR) of the Italian National Research Council (CNR) in Pisa where he held the position of Research Assistant. Since 2001 he has been with the Department of Information Engineering of the University of Pisa where he is currently an Associate Professor of Telecommunications. His research interests are in wireless communication theory, with emphasis on synchronization algorithms and channel estimation in multiple-access communication systems. Nevio Benvenuto received the Laurea degree from the University of Padova, Padova, Italy, and the Ph.D. degree from the University of Massachusetts, Amherst, in 1976 and 1983, respectively, both in electrical engineering. From 1983 to 1985 he was with AT&T Bell Laboratories, Holmdel, NJ, working on signal analysis problems. He spent the next three years alternating between the University of Padova, where he worked on communication systems research, and Bell Laboratories, as a Visiting Professor. From 1987 to 1990, he was a member of the faculty at the University of Ancona. He was a member of the faculty at the University of L'Aquila from 1994 to 1995. Currently, he is a Professor in the Electrical Engineering Department, University of Padova. His research interests include voice and data communications, digital radio, and signal processing. Silvano Pupolin received the Laurea degree in Electronic Engineering from the University of Padova, Italy, in 1970. Since then he joined the Department of Information Engineering, University of Padova, where currently is Full Professor of Electrical Communications. He was Chairman of the Faculty of Electronic Engineering from 1990 to 1994, Chairman of the PhD Course in Electronics and Telecommunications Engineering from 1991 to 1997 and Director of the PhD School in Information Engineering from 2004. Also, he was member of the programming and development committee from 1997 to 2002 and member of Scientific Committee from 1996 to 2001 of the University of Padova; member of the budget Committee of the Faculty of Engineering from 2003. He has been actively engaged in research on: Digital communication systems over copper wires and fiber optics; Spread spectrum communication systems; Design of large reliable communications networks; Effects of phase noise and HPA nonlinearities in OFDM systems; 3G mobile radio communications systems (UTRA-FDD and TDD) and beyond 3G (OFDM modulation and MC CDMA); Packet radio, Ad-hoc networks with the use of Bluetooth and WLAN. He was Chairman of the 9-th and 10-th Tyrrhenian International Workshop on Digital Communications devoted to “Broadband Wireless Communications” and to “Multimedia Communications”, respectively, and he was General Chair of the 7th International Symposium on Wireless Personal Multimedia Communications (WPMC'04). He spent the summer 1985 at AT&T Bell Laboratories on leave from Padova, doing research on digital radio systems. He was Principal investigator for research projects entitled “Variable bit rate mobile radio communication systems for multimedia applications”, “OFDM Systems with Applications to WLAN Networks”, and “MC-CDMA: an air interface for the 4th generation of wireless systems”.     

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).     

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).     

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.     

Cooperative-diversity slotted ALOHA

We propose a cooperative-diversity technique for ad hoc networks based on the decode-and-forward relaying strategy. We develop a MAC protocol based on slotted ALOHA that allows neighbors of a transmitter to act as relays and forward a packet toward its final destination when the transmission to the intended recipient fails. The proposed technique provides additional robustness against fading, packet collisions and radio mobility. Network simulations confirm that under heavy traffic conditions, in which every radio always has packets to send, the proposed cooperative-diversity slotted-ALOHA protocol can provide a higher one-hop and end-to-end throughput than the standard slotted-ALOHA protocol can. A similar advantage in end-to-end delay can be obtained when the traffic is light. As a result, the proposed cooperative-diversity ALOHA protocol can be used to improve these measures of Quality of Service (QoS) in ad hoc wireless networks. John M. Shea (S’92–M’99) received the B.S. (with highest honors) in Computer Engineering from Clemson University in 1993 and the M.S. and Ph.D. degrees in electrical engineering from Clemson University in 1995 and 1998, respectively. Dr. Shea is currently an Associate Professor of electrical and computer engineering at the University of Florida. Prior to that, he was an Assistant Professor at the University of Florida from July 1999 to August 2005 and a post-doctoral research fellow at Clemson University from January 1999 to August 1999. He was a research assistant in the Wireless Communications Program at Clemson University from 1993 to 1998. He is currently engaged in research on wireless communications with emphasis on error-control coding, cross-layer protocol design, cooperative diversity techniques, and hybrid ARQ. Dr. Shea was selected as a Finalist for the 2004 Eta Kappa Nu Outstanding Young Electrical Engineer Award. He received the Ellersick Award from the IEEE Communications Society in 1996. Dr. Shea was a National Science Foundation Fellow from 1994 to 1998. He is an Associate Editor for the IEEE Transactions on Vehicular Technology. Tan F. Wong received the B.Sc. degree (1st class honors) in electronic engineering from the Chinese University of Hong Kong in 1991, and the M.S.E.E. and Ph.D. degrees in electrical engineering from Purdue University in 1992 and 1997, respectively. He was a research engineer working on the high speed wireless networks project in the Department of Electronics at Macquarie University, Sydney, Australia. He also served as a post-doctoral research associate in the School of Electrical and Computer Engineering at Purdue University. Since August 1998 he has been with the University of Florida, where he is currently an associate professor of electrical and computer engineering. He serves as Editor for Wideband and Multiple Access Wireless Systems for the IEEE Transactions on Communications and as the Editor for the IEEE Transactions on Vehicular Technology.     

The ultra-wide bandwidth outdoor channel: From measurement campaign to statistical modelling

This paper proposes an investigation of the propagation behaviour for Ultra-Wide Bandwidth (UWB) signals in outdoor environments. Specifically, we first report on the results of an extensive measurement campaign carried out in three selected scenarios, namely “forest”, “hilly” and “sub-urban” environments. Then, we present the statistical model derived through the post-processing of collected samples by the CLEAN algorithm. While an extensive collection of results is provided in the paper, the main achievements can be summarized as follows: (i) the path-loss exponent varies from 2 to 3.5 and depends on the reference scenario and on the height of transmission and reception equipments with respect to the ground floor, (ii) the local mean of the received power experiences a Log-Normal shadowing with a standard deviation that may depend on the azimuth position, (iii) the statistics of the first received echo in the small-scale analysis also well fit a Log-Normal distribution; (iv) the delay spread in the small-scale multipath scenario turns out to be quite small (i.e. roughly 10 ns in the forest scenario and less than 32 ns in the sub-urban scenario). Marco Di Renzo (S’05) received the laurea degree (cum laude) in Electronic Engineering from the University of L’Aquila, Italy, in 2003. In 2002 he was with the Center of Excellence in Research DEWS (Design Methodologies for Embedded Controllers, Wireless Interconnections and System–on-Chip) at the Department of Electrical Engineering, University of L’Aquila, doing research on the analysis and design of Ultra Wide Band digital receiver architectures. Since 2003 he has been with the Department of Electrical Engineering, University of L’Aquila, where he worked on channel sounding and modelling for Ultra Wide Band systems and where he is currently pursuing his Ph.D. degree in Electric and Information Engineering. His current research activity is focused on channel modelling, synchronization and detection theory with specific interest to the Ultra Wide Band technology. In 2004 he played a key role in the successful creation of WEST Aquila S.r.l. (Wireless Embedded Systems Technologies Aquila), a R&D Spin-Off of the University of L’Aquila and the Center of Excellence in Research DEWS, where he currently holds the position of research engineer. Fabio Graziosi (S’96–M’97) was born in L’Aquila, Italy, in 1968. He received the Laurea degree (cum laude) and Ph.D. degree in electronic engineering from the University of L’Aquila, L’Aquila, Italy, in 1993 and 1997, respectively. Since February 1997 he has been with the Department of Electrical Engineering, at the University of L’Aquila, where he currently holds the position of Associate Professor. His current research interests are mainly focused on wireless communication systems with emphasis on wireless sensor networks and ultra wide band communication techniques. He is involved in major national and European research projects in the field of wireless systems. He is member of the Executive Committee of the Center of Excellence DEWS and serves as Chairman of the Board of Directors of WEST Aquila S.r.l., a Spin-off R&D Company of the University of L’Aquila and Center of Excellence DEWS, founded in December 2004. Riccardo Minutolo works in Thales Italia in the R&D department. He graduated in Electronic Engineering in the University of L’Aquila, in 1999. He joined Thomson-csf in 1999 working as junior engineer in the Radio propagation, interference and software development. In that period he gained expertise in HF, VHF, UHF, SHF radio propagation. In 2002 he joined Thales Italy (ex-Thomson-csf) working in the ad hoc networking area. In 2002 he was the National coordinator of a 3 years European international project (Euclide UWB). The Euclide UWB project aimed to study and research the potentiality of the emerging UWB technology for civil security and military purposes. Since 2002 his major areas of interest are: radio propagation, UWB physical layer, MAC and networking. Mauro Montanari was born in 1950 in Rimini and graduated in Electronic Engineering at Bologna University in 1974. He joined in 1976 Telettra, a national telecommunication company, working since the beginning in Defence R&D activities. His first experience was in the field of advanced automatic antenna matching unit in HF band. Afterwards he mastered, staying for several time periods in TRW—Redondo Beach/California, the technical issue of protecting radio communications through Spread Spectrum communications systems, in view of an important application to a new generation of tactical radio systems in VHF frequency band. On this topic he is co-author, with Prof. S. Pupolin of Padua University, of the book “Spread Spectrum Communications Systems” Collana Scientifica Telettra). From 1991 to 1998 he was responsible of the R&D Department within the Defence Division of Alcatel Italia (formerly Telettra) and in this position he managed several R&D projects: (i) Triservice Digital Network for the Italian MOD, in cooperation with Selenia Communications; (ii) SCRA (Single Channel Radio Access) and network management system for the Italian Army tactical network (SOTRIN) as a partner of Catrin Consortium; (iii) A new generation of radio equipment in HF band for fixed applications; (iv) High speed HF modem, according to several NATO waveforms; (v) HF fixed network for Italia Ministry of Foreign Affairs; (vi) Wide band Interception and jamming systems in HF band. Since 1999, he is responsible, within Thales Italia SpA—Land and Joint Systems Division, of Advanced Studies area with the task of promoting in the company new emerging technologies, specifically in the field of Wireless LAN, Tactical Internet, sensor networks, Ultra Wide Band for military applications and plasma antennas. This role includes establishing relations with most Thales R&D centres located in Europe and promoting new cooperative activities in new advanced technological areas. He also manages scientific relation with several Italian Universities. Fortunato Santucci (S’93–M’95–SM’00) was born at L’Aquila, Italy, in 1964. He received the laurea degree and the Ph.D. degree in Electronic Engineering from the University of L’Aquila, Italy, in 1989 and 1994, respectively. In 1989 he was with Selenia Spazio S.p.a., Rome, working on VSAT networks design. In 1991–1992 he was at the Solid State Electronics Institute (I.E.S.S.) of the National Research Council (C.N.R.), Rome, doing research on superconductor receivers for millimeter wave satellite systems. Since 1994 he has been with the Department of Electrical Engineering, University of L’Aquila, where he currently holds the position of Associate Professor. In 1996 he was a visiting researcher at the Department of Electrical and Computer Engineering of the University of Victoria, BC, Canada, where he researched on CDMA networks. His current research activity is focused on communication theory, access control and radio resource management in wireless systems, with special emphasis on technologies for networked embedded systems. He has participated in major national and European research programs in wireless mobile communications and coordinates research programs funded by industrial partners. He has been a reviewer for major technical journal in telecommunications and a session chairman in various conferences. He currently serves as an Editor for the IEEE Transactions on Communications and Kluwer Telecommunications Systems. He has been/is in the TPC of several conferences in communications. He is a Senior Member of the IEEE and is a member of the Communications Theory Committee. He is in the Executive Committee of the Center of Excellence DEWS at the University of L’Aquila and in the Executive Committee of CNIT.     

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.     

Phase Noise Spectral Limits in OFDM Systems

OFDM is recognized to be one of the best transmission techniques for wideband wireless communication systems. However, it exhibits two main drawbacks: its large amplitude fluctuation and its sensitivity to phase noise. Here we consider the phase noise impairments, taking care of the phase noise spectrum, which diverges form the classical Wiener model as the carrier frequency increases. Moreover, we show that the phase noise distortion can be decomposed in two terms, one dependent on the symbol under detection and the other dependent on the symbols of adjacent subcarriers, so that the performance degradation depends on both the constellation used in each subcarrier and the phase noise spectrum. As a consequence of this new results, the penalty due to phase noise expressed in terms of the average signal/noise plus interference ratio is not applicable in the case of modulations with non-constant amplitude constellations, such as 16- or 64-QAM. The method proposed here achieves a good accuracy, while keeping a low computational complexity, and it is confirmed by simulations. Roberto Corvaja was born in Padova (Italy) in 1967. He graduated at the Universisty of Padova in Electronic Enginering on 1990 and got his Ph.D. at the Univeristy of Padova in 1994. Since 1994 he is with the Dipartimento di Elettronica e Informatica of the University of Padova as a researcher and assistant professor on digital communications. Between 1994 and 1995 he spent 8 months at Hewlett-Packard Laboratories, Bristol (UK), working on equalization for a DECT receiver. His research activity in the past has regarded optical fibre communications systems and now is devoted to wireless communication systems. Silvano Pupolin was born in Venice, Italy, on February 17, 1947. He received the Laurea degree in Electronic Engineering from the University of Padova, Padova, Italy, in 1970. Since then he joined the Dipartimento di Elettronica e Informatica of the Universita' di Padova, where he currently is a Full Professor of Electrical Communications. He spent the summer 1985 at AT&T Bell Laboratories on leave from Padova, doing research on digital radio systems. He has been actively engaged in researches on digital communication systems since 1970. The topics covered has been: performance of baseband digital comunication systems, line encoding for spectral shaping, timing extraction, direct detection fiber optic system, spread spectrum communication systems, digital radio communications, with emphasis to the adaptive linearization of the High-Power-Amplifier. Actually, he is actively engaged in researches on digital radio, spread s pectrum systems, packet radio networks, personal communication systems and Cellular access to broadband systems for interactive communications. He is also National Project leader for a research on Personal Communication Systems. Dr. Pupolin is a Senior Member of IEEE and Member of AEI.     

A Joint MAC-PHY Approach for Medium Access Control in VBR MC-CDMA Broadband Indoor Connections

Multicarrier Code Division Multiple Access (MC-CDMA) techniques were originally proposed at mid of 90's for wideband multi-user communications in wireless environments characterized by hostile propagation characteristics. In this work, the design of a MC-CDMA-based infrastructure is considered for VBR broadband indoor connections with real-time asynchronous multiple access. At the present time, Broadband Fixed Wireless Access (BFWA) standards like IEEE 802.16 and HIPERMAN can bring broadband services inside buildings, but indoor access should be conveniently provided by a local area connection. The capability of MC-CDMA of supporting asynchronous multi-user variable-bit-rate (VBR) transmission is exploited jointly with an efficient and real-time Medium Access Control (MAC) strategy in order to allow a significant number of indoor VBR users to transmit information in CDMA modality with different quality of service (QoS) profiles. Different classes of users are defined at the MAC level. The available radio resources (i.e. the orthogonal subchannels) are selectively attributed to transmitting users depending on their performance achieved at MAC level and measured by an “intelligent” gateway. When the quality level is not satisfactory for one or more users, the AP issues a decrease of the data rate for such users while providing them with an increased number of subcarriers, guaranteeing a slower transmission fostered against frequency-selective channel distortions. The paper presents an overview of the system and tests its performance through extensive simulations. The proposed joint MAC-PHY approach demonstrates good performance in terms of achieved throughput and high flexibility in radio resource management.This work has been partially supported in Italy by the “NETMOBS -Network-supported Mobility for the Student” – Create-NET project funding, 2005. Claudio Sacchi was born in Genoa (Italy) in 1965. He obtained the Laurea degree in Electronic Engineering, and the Ph.D. in Space Science and Engineering at the University of Genoa (Italy). Since August 2002, Dr. Sacchi has been holding a position as assistant professor at the Faculty of Engineering of the University of Trento (Italy). In 2004, he was appointed by the Department of Information and Communication Technology of the University of Trento as leader of the Research Program titled: “Wireless and Satellite Communications”. The research interests of Dr. Sacchi are focused on wideband mobile and satellite transmission systems based on space, time and frequency diversity, multi-user receivers based on non conventional techniques, and high-frequency ultra-wideband satellite communications. Dr. Sacchi is author and co-author of more than 40 papers published in international journals and conferences. He is member of IEEE. Giovanni Berlanda Scorza was born in Trento (Italy) in 1978. He received the Laurea in Telecommunications Engineering in 2002 at the “Politecnico di Milano” Technical University. Since October 2002, he is a Ph.D student at the Information and Communications Technologies (ICT) International Doctorate School of the University of Trento. His research interests mainly concern with specific aspects related to OFDM and MC-CDMA transmission techniques like e.g.: computationally-affordable multi-user receivers, Medium Access Control strategies, multicarrier-based multiplexing of multi-layered MPEG-4 coded video streams, etc. Fabrizio Granelli was born in Genoa in 1972. He received the “Laurea” (M.Sc.) degree in Electronic Engineering from the University of Genoa, Italy, in 1997, and the Ph.D. in Telecommunications from the same university, in 2001. Since 2000 he is carrying on his teaching activity as Assistant Professor in Telecommunications at the Dept. of Information and Communication Technology – University of Trento (Italy). In August 2004, he was visiting professor at the State University of Campinas (Brasil). He is author or co-author of more than 50 papers published in international journals, books and conferences, and he is member of the Technical Committee of the International Conference on Communications (ICC2003, ICC2004 and ICC2005) and Global Telecommunications Conference (GLOBECOM2003 and GLOBECOM2004). Dr. Granelli is guest-editor of ACM Journal on Mobile Networks and Applications, special issue on “WLAN Optimization at the MAC and Network Levels” and Co-Chair of 10th IEEE Workshop on Computer-Aided Modeling, Analysis, and Design of Communication Links and Networks (CAMAD'04). Dr. Granelli is General Vice-Chair of the First International Conference on Wireless Internet (WICON'05). His main research activities are in the field of networking and signal processing, with particular reference to network performance modeling, medium access control, wireless networks, next-generation IP, and video transmission over packet networks. Francesco G.B. De Natale received the Laurea in Electronic Engineering in 1990, and the Ph.D. in Telecommunications in 1994, both from the University of Genoa, Italy. In 1995–96 he was Visiting Professor at the University of Trento, Italy and from 1996 to 1999 Assistant Professor at the University of Cagliari, Italy. At present he is Full Professor of Telecommunications at the University of Trento, where he coordinates the didactic activities of the Bachelor and Master Courses in Telecommunications Engineering. Prof. De Natale is Deputy Head of the Dept. of Information and Communication Technologies, where he leads the research activities of the Multimedia Communications Lab. The research interests of Prof. De Natale are focused on image and signal processing, with particular attention to multimedia data compression, processing and transmission. He was General Co-Chair of the Packet Video Workshop in 2000 and is Technical Program Co-Chair of the IEEE Intl. Conf. on Image Processing to be held in 2005. In 1998 he was co-recipient of the IEEE Chester-Sall Best Paper Award. Prof. De Natale is a Senior Member of IEEE.     

Physical-layer air interface solutions for broadband high-speed wireless cellular systems

We propose the physical-layer (PHY) air interface solutions for downlink and uplink transmissions in broadband high-speed wireless cellular systems. A system based on low-density parity-check (LDPC) coded multiple-input-multiple-output (MIMO) orthogonal frequency-division multiplexing (OFDM) time-division multiple-accessing (TDMA) (with scheduling) is proposed for downlink transmission; and a system based on orthogonal space-time block coded (STBC) multi-carrier code-division multiple-accessing (MC-CDMA) is proposed for uplink transmission. The proposed scheme can support ∼100 Mbps peak rate over 25 MHz bandwidth downlink channels and ∼30 Mbps sum rate of multiple users over 25 MHz uplink channels. Moreover, the proposed solutions provide excellent performance and reasonable complexity for mobile station and for base station. Ben Lu received the B.S. and M.S. degrees in electrical engineering from Southeast University, Nanjing, China, in 1994 and 1997; the Ph.D. degree from Texas A & M University in 2002. From 1994 to 1997, he was a Research Assistant with National Mobile Communications Research Laboratory at Southeast University, China. From 1997 to 1998, he was with the CDMA Research Department of Zhongxing Telecommunication Equipment Co., Shanghai, China. From 2002 to 2004, he worked for the project of high-speed wireless packet data transmission (4G prototype) at NEC Laboratories America, Princeton, New Jersey. He is now with Silicon Laboratories. His research interests include the signal processing and error-control coding for mobile and wireless communication systems. Xiaodong Wang received the B.S. degree in Electrical Engineering and Applied Mathematics (with the highest honor) from Shanghai Jiao Tong University, Shanghai, China, in 1992; the M.S. degree in Electrical and Computer Engineering from Purdue University in 1995; and the Ph.D degree in Electrical Engineering from Princeton University in 1998. From July 1998 to December 2001, he was an Assistant Professor in the Department of Electrical Engineering, Texas A&M University. In January 2002, he joined the faculty of the Department of Electrical Engineering, Columbia University. Dr. Wang’s research interests fall in the general areas of computing, signal processing and communications. He has worked in the areas of digital communications, digital signal processing, parallel and distributed computing, nanoelectronics and bioinformatics, and has published extensively in these areas. Among his publications is a recent book entitled “Wireless Communication Systems: Advanced Techniques for Signal Reception”, published by Prentice Hall, Upper Saddle River, in 2003. His current research interests include wireless communications, Monte Carlo-based statistical signal processing, and genomic signal processing. Dr. Wang received the 1999 NSF CAREER Award, and the 2001 IEEE Communications Society and Information Theory Society Joint Paper Award. He currently serves as an Associate Editor for the IEEE Transactions on Communications, the IEEE Transactions on Wireless Communications, the IEEE Transactions on Signal Processing, and the IEEE Transactions on Information Theory. Mohammad Madihian (S’78-M’83-SM’88-F’98) received his Ph.D in electronic engineering from Shizuoka University, Hamamatsu, Japan, in 1983. He is presently the Chief Patent Officer and Department Head, NEC Laboratories America, Inc., Princeton, New Jersey, where he conducts Microwave as well as PHY/MAC layer signal processing activities for high-speed wireless networks and personal communications applications. He holds 35 Japan/US patents and has authored/co-authored more than 130 technical publications including 25 invited talks. He has received 8 NEC Distinguished R&D Achievement Awards, the 1988 IEEE MTT-S Best Paper Microwave Prize, and 1998 IEEE Fellow Award. He has served as Guest Editor to the IEEE Journal of Solid-State Circuits, Japan IEICE Transactions on Electronics, and IEEE Transactions on Microwave Theory and Techniques. He is currently serving on the IEEE Speaker’s Bureau, IEEE Compound Semiconductor IC Symposium Executive Committee, IEEE Radio and Wireless Symposium Executive Committee, IEEE International Microwave Symposium Technical Program Committee, IEEE MTT-6 Subcommittee, IEEE MTT Editorial Board, and Technical Program Committee of International Conference on Solid State Devices and Materials. Dr. Madihian is an Adjunct Professor at Electrical and Computer Engineering Department, Drexel University, Philadelphia, Pennsylvania.     

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).     

Coordinated load balancing, handoff/cell-site selection, and scheduling in multi-cell packet data systems

We investigate a wireless system of multiple cells, each having a downlink shared channel in support of high-speed packet data services. In practice, such a system consists of hierarchically organized entities including a central server, Base Stations (BSs), and Mobile Stations (MSs). Our goal is to improve global resource utilization and reduce regional congestion given asymmetric arrivals and departures of mobile users, a goal requiring load balancing among multiple cells. For this purpose, we propose a scalable cross-layer framework to coordinate packet-level scheduling, call-level cell-site selection and handoff, and system-level cell coverage based on load, throughput, and channel measurements. In this framework, an opportunistic scheduling algorithm—the weighted Alpha-Rule—exploits the gain of multiuser diversity in each cell independently, trading aggregate (mean) downlink throughput for fairness and minimum rate guarantees among MSs. Each MS adapts to its channel dynamics and the load fluctuations in neighboring cells, in accordance with MSs’ mobility or their arrival and departure, by initiating load-aware handoff and cell-site selection. The central server adjusts schedulers of all cells to coordinate their coverage by prompting cell breathing or distributed MS handoffs. Across the whole system, BSs and MSs constantly monitor their load, throughput, or channel quality in order to facilitate the overall system coordination. Our specific contributions in such a framework are highlighted by the minimum-rate guaranteed weighted Alpha-Rule scheduling, the load-aware MS handoff/cell-site selection, and the Media Access Control (MAC)-layer cell breathing. Our evaluations show that the proposed framework can improve global resource utilization and load balancing, resulting in a smaller blocking rate of MS arrivals without extra resources while the aggregate throughput remains roughly the same or improved at the hot-spots. Our simulation tests also show that the coordinated system is robust to dynamic load fluctuations and is scalable to both the system dimension and the size of MS population. Aimin Sang received a Ph.D. from the University of Texas at Austin in 2001. His Ph.D. dissertation is on the measurement-based traffic management for QoS guarantee in multi-service networks. From May 2000 to July 2002, he was a member of technical staff and software engineer at Santera System Inc., a startup company in designing and implementing the next-generation multi-service gateway. His duty was to design, implement, and test core traffic management algorithms on the switch fabric and control boards, integrating IP routing, ATM switching, and Class 4 and 5 telephony switching functionalities for multi-service Internet access at the Central Offices. From July 2002 to Nov. 2002, he was a post-doc at UT-Austin, researching on VPN provisioning and ad hoc sensor networks. He joined NEC Lab America in Nov. 2002. Dr. Sang is currently a research staff member in Broadband & Mobile Networking Department, NEC Lab. America, focusing on cross-layer design of 4G wireless systems, such as 4G Cellular base station, WiMax/WLAN systems, and their inter-networking architecture. His duty is to develop the core technologies including the radio resource management and QoS schemes over an IP-optimized MC-CDMA or OFCDM/MIMO air interfaces. He is also interested in ad hoc sensor networks and personal area networks. Xiaodong Wang received the B.S. degree in Electrical Engineering and Applied Mathematics (with the highest honor) from Shanghai Jiao Tong University, Shanghai, China, in 1992; the M.S. degree in Electrical and Computer Engineering from Purdue University in 1995; and the Ph.D degree in Electrical Engineering from Princeton University in 1998. From July 1998 to December 2001, he was an Assistant Professor in the Department of Electrical Engineering, Texas A&M University. In January 2002, he joined the faculty of the Department of Electrical Engineering, Columbia University. Dr. Wang’s research interests fall in the general areas of computing, signal processing and communications. He has worked in the areas of digital communications, digital signal processing, parallel and distributed computing, nanoelectronics and bioinformatics, and has published extensively in these areas. Among his publications is a recent book entitled “Wireless Communication Systems: Advanced Techniques for Signal Reception”, published by Prentice Hall, Upper Saddle River, in 2003. His current research interests include wireless communications, Monte Carlo-based statistical signal processing, and genomic signal processing. Dr. Wang received the 1999 NSF CAREER Award, and the 2001 IEEE Communications Society and Information Theory Society Joint Paper Award. He currently serves as an Associate Editor for the IEEE Transactions on Communications, the IEEE Transactions on Wireless Communications, the IEEE Transactions on Signal Processing, and the IEEE Transactions on Information Theory. Mohammad Madihian received the Ph.D. Degree in Electronic Engineering from Shizuoka University, Japan, in 1983. He joined NEC Central Research Laboratories, Kawasaki, Japan, where he worked on research and development of Si and GaAs device-based digital as well as microwave and millimeter-wave monolithic IC’s. In 1999, he moved to NEC Laboratories America, Inc., Princeton, New Jersey, and is presently the Department Head and Chief Patent Officer. He conducts PHY/MAC layer signal processing activities for high-speed wireless networks and personal communications applications. He has authored or co-authored more than 130 scientific publications including 20 invited talks, and holds 35 Japan/US patents. Dr. Madihian has received the IEEE MTT-S Best Paper Microwave Prize in 1988, and the IEEE Fellow Award in 1998. He holds 8 NEC Distinguished R&D Achievement Awards. He has served as Guest Editor to the IEEE Journal of Solid-State Circuits, Japan IEICE Transactions on Electronics, and IEEE Transactions on Microwave Theory and Techniques. He is presently serving on the IEEE Speaker’s Bureau, IEEE Compound Semiconductor IC Symposium (CSICS) Executive Committee, IEEE Radio and Wireless Conference Steering Committee, IEEE International Microwave Symposium (IMS) Technical Program Committee, IEEE MTT-6 Subcommittee, IEEE MTT Editorial Board, and Technical Program Committee of International Conference on Solid State Devices and Materials (SSDM). Dr. Madihian is an Adjunct Professor at Electrical and Computer Engineering Department, Drexel University, Philadelphia, Pennsylvania. Richard D. Gitlin Is currently President of Innovatia Networks a wireless startup company and a member of the Board of Directors of PCTEL [NASDAQ: PCTI]. Previously he was Visiting Professor of Electrical Engineering at Columbia University and Vice President, Technology of NEC Laboratories America. After receiving his doctorate from Columbia University, he was with Lucent Technologies (Bell Labs), where for more than 32 years he held several research and executive positions, including Senior Vice President, Communications Systems Research and Chief Technical Officer and VP of R&D of Lucent’s Data Networking Business Unit. Throughout his career Dr. Gitlin has both personally conducted and led pioneering research and development in digital communications and networking, digital signal processing, wireless systems, and broadband networking that has resulted in many innovative products, including: the industry leading ATLANTA ATM Chipset, the world’s first 20 gigabit/sec ATM switch, wire-speed and quality of service [QoS]-aware IP switches, multicode CDMA (IS-95B), and the record-setting BLAST broadband fixed-wireless loop system based on advanced spatial domain (smart antenna) processing. Earlier in his career he led the team that pioneered the V.32/V.34 voice-band modems, and in 1986 he was a co-inventor of the DSL technology. He has more than 90 referred publications, is the recipient of three prize papers, has delivered numerous keynotes, and he holds 43 US patents, and co-author of the text Data Communications. He currently serves on the Editorial Boards of Mobile Networks and Applications and the Journal of Communications Networks (JCN). Dr. Gitlin has been elected as a member of the US National Academy of Engineering, is a Fellow of the IEEE, and is a Bell Laboratories Fellow. Dr. Gitlin has served as Chair of the Communication Theory Committee of the IEEE Communications Society, as a member of the COMSOC Awards Board, as Editor for communication theory of the IEEE Transactions on Communications, as a member of the Board of Governors of the IEEE Communications Society, and a member of the Nominations and Elections Board. He has served on the Advisory Committee for Computer Science and Engineering (CISE) of the National Science Foundation.     

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.     

Packet concatenation at the IP level for performance enhancement in wireless local area networks

Wireless local area networks experience performance degradation in presence of small packets. The main reason for that is the large overhead added at the physical and link layers. This paper proposes a concatenation algorithm which groups IP layer packets prior to transmission, called PAC-IP. As a result, the overhead added at the physical and the link layers is shared among the grouped packets. Along with performance improvement, PAC-IP enables packet-based fairness in medium access as well as includes QoS support module handling delay-sensitive traffic demands. The performance of the proposed algorithm is evaluated through both simulations and an experimental WLAN testbed environment covering the single-hop and the widespread infrastructure network scenarios. Obtained results underline significant performance enhancement in different operating scenarios and channel conditions. Dzmitry Kliazovich received his Masters degree in Telecommunication science from Belarusian State University of Informatics and Radioelectronics in 2002. He is currently working towards the Ph.D. degree in University of Trento, Italy. From September 2005 to February 2006 he was a visiting researcher at the Computer Science Department of the University of California at Los Angeles. He is an author of more than 20 research papers published in international books, journals and conference proceedings. His main research interest lies in field of wireless networking with a focus on performance optimization and cross-layer design. Fabrizio Granelli was born in Genoa in 1972. He received the “Laurea” (M.Sc.) degree in Electronic Engineering from the University of Genoa, Italy, in 1997, with a thesis on video coding, awarded with the TELECOM Italy prize, and the Ph.D. in Telecommunications from the same university, in 2001. Since 2000 he is carrying on his teaching activity as Assistant Professor in Telecommunications at the Dept. of Information and Communication Technology—University of Trento (Italy). In August 2004, he was visiting professor at the State University of Campinas (Brasil). He is author or co-author of more than 60 papers published in international journals, books and conferences, and he is member of the Technical Committee of the International Conference on Communications (from 2003 to 2007) and Global Telecommunications Conference (GLOBECOM2003 and GLOBECOM2004). Dr. Granelli is guest-editor of ACM Journal on Mobile Networks and Applications, special issues on “WLAN Optimization at the MAC and Network Levels” and “Ultra-Wide Band for Sensor Networks”, and Co-Chair of 10th IEEE Workshop on Computer-Aided Modeling, Analysis, and Design of Communication Links and Networks (CAMAD’04). Dr. Granelli is General Vice-Chair of the First International Conference on Wireless Internet (WICON’05) and General Chair of the 11th IEEE Workshop on Computer-Aided Modeling, Analysis, and Design of Communication Links and Networks (CAMAD’06). His main research activities are in the field of networking and signal processing, with particular reference to network performance modeling, medium access control, wireless networks, cognitive radio systems, and video transmission over packet networks. He is Senior Member of IEEE and Associate Editor of IEEE Communications Letters.     

Cross-layer radio resource allocation in packet CDMA wireless mobile networks

An efficient radio resource allocation scheme is crucial for guaranteeing the quality of service (QoS) requirements and fully utilizing the scarce radio resources in wireless mobile networks. Most of previous studies of radio resource allocation in traditional wireless networks concentrates on network layer connection blocking probability QoS. In this paper, we show that physical layer techniques and QoS have significant impacts on network layer QoS. We use a concept of cross-layer effective bandwidth to measure the unified radio resource usage taking into account both physical layer linear minimum-mean square error (LMMSE) receivers and varying statistical characteristics of the packet traffic in code devision multiple access (CDMA) networks. We demonstrate the similarity between traditional circuit-switched networks and packet CDMA networks, which enables rich theories developed in traditional wireless mobile networks to be used in packet CDMA networks. Moreover, since both physical layer signal-to-interference ratio (SIR) QoS and network layer connection blocking probability QoS are considered simultaneously, we can explore the tradeoff between physical layer QoS and network layer QoS in packet CDMA networks. This work is supported by Natural Science and Engineering Research Council of Canada. Please address all correspondence to Professor Vikram Krishnamurthy at the above address. Fei Yu received the Ph.D. degree in electrical engineering from the University of British Columbia in 2003. From 2002 to 2004, he was with Ericsson (in Lund, Sweden), where he worked on the research and development of dual mode UMTS/GPRS handsets. From 2005, he has been working in Silicon Valley at a start-up, where he conducts research and development in the areas of advanced wireless communication technologies and new standards. After completing the PhD, he has been a research associate in the Department of Electrical and Computer Engineering at the University of British Columbia. His research interests include cross-layer optimization, QoS provisioning and security in wireless networks. Vikram Krishnamurthy (S’90-M’91-SM’99-F’05) was born in 1966. He received his bachelor’s degree from the University of Auckland, New Zealand in 1988, and Ph.D. from the Australian National University, Canberra, in 1992. Since 2002, he has been a professor and Canada Research Chair at the Department of Electrical Engineering, University of British Columbia, Vancouver, Canada. Prior to this he was a chaired professor at the Department of Electrical and Electronic Engineering, University of Melbourne, Australia. His research interests span several areas including ion channels and nanobiology, stochastic scheduling and control, statistical signal processing and wireless telecommunications. Dr. Krishnamurthy has served as associate editor for IEEE Transactions on Signal Processing, IEEE Transactions Aerospace and Electronic Systems, IEEE Transactions Nanobioscience, IEEE Transactions Circuits and Systems II, Systems and Control Letters and European Journal of Applied Signal Processing. He was guest editor of a special issue of IEEE Transactions on NanoBioScience, March 2005 on bio-nanotubes.     

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).