Cross-Layering Approaches in Wireless Ad Hoc Networks

Wireless ad hoc networks are temporary formed, infrastructureless networks. Due to the unstable channel conditions and network connectivity, their characteristics impose serious challenges in front of network designers. The layering approach to network design does not fit the ad hoc environment well. Therefore, various cross-layering approaches, where protocol layers actively interact, exchange inherent layer information and fine tune their parameters according to the network status are becoming increasingly popular. This paper presents an in-depth analysis of the latest cross-layering approaches for wireless ad hoc networks supported by several examples. A special emphasis is put on the link and network layer related cross-layer designs. Several link adaptation and efficient service discovery schemes are elaborated through analytical and simulation studies. Their performance shows the potentials of the cross-layering for boosting system characteristics in wireless ad hoc networks. Liljana Gavrilovska currently holds a position of full professor at Faculty of Electrical Engineering, University “St. Cyril and Metodij” – Skopje, Macedonia. She is chief of Telecommunications Laboratory and teaches undergraduate courses in telecommunication networks, data transmission and switching and traffic theory, and graduate courses in wireless, mobile and personal networks, teletraffic engineering and planning, and broadband multiservices networks. In 2000 she joined the Center for PersonKommunikation, Aalborg University, Denmark, as a visiting professor and during 2001--2002 she held a position of associate research professor at the same university. Currently she holds a part-time position of associated research professor with Center for Teleinfrastructur (CTIF). Prof. Gavrilovska was involved in several EU (ACTS ASAP, IST PACWOMAN, MAGNET, TEMPUS) and national/international projects. She published numerous conference and journal papers and participated in several workshops. At the moment she is working on the book “Ad Hoc Networking Towards Seamless Communications” together with prof. R. Prasad. Her research interests include wireless and personal area networks, ad hoc networking, networking protocols, traffic analysis, QoS, and optimization techniques. She is a senior member of IEEE and serves as a Chair of Macedonian Communication Chapter.     

Provisioning link layer proportional service differentiation in wireless networks with smart antennas

In this paper, we present a collision free MAC protocol for wireless networks with smart antennas that provides proportional service differentiation to various classes of traffic based on their respective bandwidth demand. The proposed protocol works for diverse physical parameters such as number of interfaces at each node, number of communication frequencies, and antenna beamwidth. To the best of our knowledge, this is the first work that provides link layer differentiated services for wireless networks with smart antennas and explores the influence of the physical parameters and network topology on the performance of the MAC layer. Ashish Deopura received his B.Tech degree in Electrical Engineering from the Indian Institute of Technology Delhi, India, in 2003, and he received his M.S. degree in Computer Systems Engineering from the University of Massachusetts Amherst, in 2005. He currently works as a Modeling Engineer for OPNET Technologies located in Bethesda, MD Professor Aura Ganz is the director of the Multimedia Networking Laboratory at the University of Massachusetts at Amherst. She has authored more than 170 journal and conference papers in the areas of multimedia wireless networks, ubiquitous computing, telemedicine, and security. She is a co-author of the book: “Multimedia Wireless Networks”, Prentice Hall, 2003. Some of her recent assignments include: general co-chair of the IEEE UWBNETS workshop, general co-chair of the IEEE BROADMED workshop, general co-chair of the Massachusetts 3rd Annual R&D Conference, keynote speaker at the NSF sponsored workshop in Mobile Computing, and invited speaker at Personal and Local Wireless Network Solutions conference, and Motorola’s Wireless Communications Futures Forum, Wireless Local Area Networks Conference. She has a PhD, MSc and BSc in Computer Science from the Technion in Israel. More details can be found at: dvd1.ecs.umass.edu/wireless.     

Energy-Efficient Operation through Interference Avoidance for Interconnected Bluetooth WPANs

A Wireless Personal Area Network (WPAN) provides wireless networking among proximate devices, usually carried by an individual. Bluetooth is a first instance of the WPAN technology. The basic networking entity in Bluetooth is a piconet. Several piconets (WPANs) can be interconnected into a scatternet, which can be considered as an extendable multi-hop ad hoc networking structure. Since Bluetooth operates in the unlicensed ISM band, each piconet uses pseudorandom frequency hopping. If collocated piconets use the same channel simultaneously, the piconets interfere with each other and the transmitted packets are lost in collisions. This interference is termed self-interference. The piconets that are networked into scatternet exhibit spatial overlapping and naturally produce multi-piconet self-interference. The collisions cause retransmissions and increase the energy spent per data portion, which results in energy-inefficient operation. To tackle this problem, in our previous work we have proposed a self-interference avoidance (SIA) mechanism. However, this basic SIA mechanism is oblivious with respect to the physical topology and does not account for the mitigation of self-interference due to the propagation effects. Furthermore, the basic SIA mechanism relies on the assumption that all piconets are using packets of identical and fixed length. In this paper we will generalize the SIA mechanism to overcome the stated restrictions. We propose the adaptive SIA (A-SIA) algorithm, which adapts the SIA algorithm to the actual interference. The simulation results show that A-SIA largely retains the energy gain offered by the SIA algorithm, while significantly improving the goodput. We also design an instance of the SIA mechanism that operates with variable-length packets, referred as generalized SIA (G-SIA) algorithm. Our simulation results show that the G-SIA algorithm offers good performance in terms of goodput and energy efficiency, but the goodput is degraded if inappropriate segmentation/reassembly policy is used. Petar Popovski received the Dipl.-Ing. in electrical engineering and M.Sc. in communication engineering from the Faculty of Electrical Engineering, Sts. Cyril and Methodius University, Skopje, Macedonia, in 1997 and 2000, respectively and a Ph.D. degree from Aalborg University, Denmark, in 2004. He is currently Assistant Research Professor at the Department of Communication Technology at the Aalborg University. His research interests are focused on wireless ad hoc networks, wireless sensor networks, and high-speed wireless multi-carrier communications. Hiroyuki Yomo received B.S. degree in communication engineering from Department of Communication Engineering, Osaka University, Osaka, Japan, in 1997, and M.S. and Ph.D. degrees in communication engineering from Department of Electronic, Information, and Energy Engineering, Graduate School of Engineering, Osaka University, Osaka Japan, in 1999 and 2002, respectively. From April 2002 to March 2004, he was a Post-doctoral Fellow in Department of Communication Technology, Aalborg University, Denmark. From April 2004 to September 2004, he was working at NEC Corporation, Japan. Since October 2004, he has been an Assistant Research Professor in Center for TeleInfrastructure (CTIF), Aalborg University, Denmark. His research interests include medium access protocols, link-layer techniques, routing protocols, and their interactions in wireless networks. Liljana Gavrilovska received her B.Sc., M.Sc. and Ph.D. from University of Skopje (76), University of Belgrade (85) and University of Skopje (95) respectively. She joined the Faculty of Electrical Engineering, University of Skopje, Republic of Macedonia, where she currently holds positions of Professor at the Institute for Telecommunications, chief of Telecommunications Laboratory and head of CWMC (Center for Wireless and Mobile Communications), working in the area of networking and mobile communications. During 2001–2002 she joined the Centre for PersonKommunikation, Aalborg University, Denmark, where she was holding a position as Associate Research Professor and was involved in several EU (ASAP, PACWOMAN, MAGNET) and national/international projects. She is still working part-time for CTiF, Aalborg University, Denmark. Her major research is concentrated on ad hoc networking, wireless and personal area networks, cross layer optimizations, future mobile systems, traffic analysis and admission techniques. She is a senior member of IEEE and serves as a Chair of the Macedonian Communications Chapter. Ramjee Prasad is a distinguished educator and researcher in the field of wireless information and multimedia communications. During February 1988–May 1999 he has been with the Telecommunications and Traffic-Control Systems Group of Delft University of Technology (DUT), The Netherlands, where he was actively involved in the area of wireless personal and multimedia communications (WPMC). He was head of the Transmission Research Section of International research Centre for Telecommunications Transmission and Radar (IRCTR) and also Founding Program Director of the Centre for Wireless Personal Communications (CWPC). As from June 1999 Ramjee Prasad joined as the Wireless Information Multimedia Communications chair and co-director of Centre for PersonKommunikation at Aalborg University, Denmark. From January 2004 he is Founding Director of the “Centre for Teleinfrastruktur (CTIF)”. He has published over 500 technical papers, and authored and co-edited 15 books about Wireless Multimedia Communications (Artech House). His research interest lies in wireless networks, packet communications, multiple access protocols, adaptive equalisers, spread-spectrum CDMA systems and multimedia communications. Prof. Prasad is the founding chairperson of the European centre of Excellence in Telecommunications known as HERMES Partnership. He is the General Chairman of International Wireless Summit (IWS 2005) to be held in Aalborg, Denmark in September 17–22, 2005. He is a fellow of the IEE, a fellow of IETE, a senior member of IEEE, a member of NERG, and a member of the Danish Engineering Society (IDA). He is advisor to several multinational companies.     

Introducing consciousness in UWB networks by hybrid modelling of admission control

We formalize a model for a self-organizing network of nodes that operate according to the UWB principle based on hybrid modelling formalism. We design the rules that lead to the formation of the network and in particular an admission control procedure that is capable to handle both continuous and discrete perturbations, while maintaining the network in a condition of stability. Cognition is introduced in the model by allowing nodes to adjust their rules of operation based on the perception of the environment by an elected node, serving as the observer, that is aware of context, evaluates, and selects one strategy of operation. Maria-Gabriella Di Benedetto obtained her Ph.D. in Telecommunications in 1987 from the University of Rome La Sapienza, Italy. In 1991, she joined the Faculty of Engineering of University of Rome La Sapienza, where currently she is a Full Professor of Telecommunications at the Infocom Department. She has held visiting positions at the Massachusetts Institute of Technology, the University of California, Berkeley, and the University of Paris XI, France. In 1994, she received the Mac Kay Professorship award from the University of California, Berkeley. Her research interests include wireless communication systems and speech science. From 1995 to 2000, she directed four European projects for the design of UMTS. Since 2000, she has been active in fostering the development of Ultra Wide Band (UWB) radio communications in Europe. Within the 5th framework, she directed for the Infocom Dept. two European projects (whyless.com and UCAN) aimed at the design and implementation of UWB ad-hoc networks. Currently, within the 6th EU Framework, her “Networking with UWB” research group participates in the PULSERS Integrated Project which will integrate UWB research and development in Europe for the next years, and in the LIAISON Integrated Project as regards the application of UWB to location-based services. She also participates in the HYCON network of excellence. Dr. Di Benedetto has co-edited several Special Issues on UWB communications and networks for several Journals including IEEE JSAC, Journal of Communications and Networks, Mobile Networks and Applications, Eurasip. In 2004, Dr. Di Benedetto co-authored with G. Giancola the first published book on UWB for communications titled “Understanding Ultra Wide Band Radio Fundamentals” and published by Prentice Hall. She recently completed the co-edition of two new books on UWB that will be published by 2005: UWB Communication Systems—A comprehensive overview, with T. Kaiser, D. Porcino, A. Molisch, and I. Oppermann, Hindawi Publishing Corporation, 2005, and Ultra Wideband Wireless Communications with H. Arslan and Z.N. Chen, John Wiley & Sons, Inc., 2005. Maria Domenica Di Benedetto obtained the “Dr. Ing.” degree (summa cum laude) of Electrical Engineering and Computer Science, University of Roma “La Sapienza” in 1976 (Mosè Ascoli Best Student Award). In 1981, she obtained the degree “Docteur-Ingénieur” and in 1987 the degree “Doctorat d’Etat ès Sciences”, Université de Paris-Sud, Orsay, France. From 1979 to 1983, she had been Research Engineer at the scientific centers of IBM in Paris and Rome. From 1983 to 1987, she had been Assistant Professor at the University of Roma “La Sapienza”. From 1987 to 1990, she had been Associate Professor at the Istituto Universitario Navale of Naples. From 1990 to 1993, had been Associate Professor at the University of Roma “La Sapienza”. Since 1994, she has been Professor of Control Theory at University of L’Aquila. From 1995 to 2002, she was Adjunct Professor, Department of EECS, University of California at Berkeley. In 1987, she was Visiting Scientist at MIT; in 1988, 1989 and 1992, Visiting Professor at the University of Michigan, Ann Arbor; in 1992, Chercheur Associé, C.N.R.S., Poste Rouge, Ecole Nationale Supérieure de Mécanique, Nantes, France; in 1990, 1992, 1994 and 1995, McKay Professor at the University of California at Berkeley. Her research interests revolve around nonlinear control and hybrid systems. She was Associate Editor of the IEEE Transactions of Automatic Control and has been Subject Editor of the International Journal of Robust and Nonlinear Control since 1995. Since 2005, she has been a member of the IFAC Technical Committee on Discrete Event and Hybrid Systems. Since 2000, she has been the Director of the Center of Excellence for Research DEWS on “Architectures and Design methodologies for Embedded controllers, Wireless interconnect and System-on-chip”, University of L’Aquila. She is IEEE Fellow and Chairperson of the Standing Committee on Fellow Nominations, IEEE Control Systems Society. Guerino Giancola received the “Laurea” degree (magna cum laude) in Telecommunications Engineering, and the Ph.D. degree in Information and Communication Engineering from University of Rome La Sapienza, in 2001 and 2005, respectively. He is currently a research affiliate at the INFOCOM Department at University of Rome La Sapienza, where is actually holding the course of “Electrical Communications” for the degree on Electronic Engineering. His research interests include the analysis and modelling of Multi User Interference in Impulse Radio systems, and the design of Medium Access Control functions and protocols for UWB ad-hoc networks. Guerino Giancola recently co-authored with Prof. Maria-Gabriella Di Benedetto a book on Ultra Wide Band from radio to the network, titled “Understanding Ultra Wide Band Radio Fundamentals” and published by Prentice Hall in June 2004. He is now involved in the European project “PULSERS—Pervasive Ultra wideband Low Spectral Energy Radio Systems” and in the European Network of Excellence “HYCON—Hybrid Control: Taming Heterogeneity and Complexity of Networked Embedded Systems”. Guerino Giancola is a member of the IEEE Communication Society.     

Sequence Number Aided Source Routing for Ad-Hoc Networks

Wireless multihop mobile networks, also known as ad hoc networks, are characterized by stochastic topology variations. Random movements of mobile hosts in and out of each other's range encumber smooth system operation and impose limitations on the network performance. Various routing protocols suitable for such networks have been proposed however implementation and performance issues are still considered top research priorities. This paper proposes a new reactive protocol that introduces the use of sequence numbers for evaluating validity of cached routing information when source routing and route caching are used. The new protocol reduces the possibility of using and spreading across the network stale routing information therefore reduces the overhead involved in finding a route. To demonstrate the performance of the proposed protocol we compare it, through a detailed simulation model, with Dynamic Source Routing (DSR) protocol which also uses source routing and route caching. Results prove that the proposed protocol effectively reduces use of stale routing information, improving performance compared to DSR in terms of both delivery ratio and routing overhead. Evangelos Papapetrou holds a Diploma and a Ph.D. in Electrical & Computer Engineering from the Aristotle University of Thessaloniki, Greece. He is currently a visiting lecturer in the Computer Science Department at the University of Ioannina, Greece, where he is engaged in teaching and research on Mobile and Satellite Communications and Telecommunications Networks. His research interests include traffic analysis and design of Satellite networks, Internet over Satellites, IP networking, routing in networks with periodic or stochastic varying topologies, MANETs and QoS in wireless mobile systems. He has served as a reviewer in several journals and Conferences relevant to mobile communications. In the past he has participated in Greek and European projects regarding satellite communications. He was also involved in COST Actions 253 and 272 and in many European projects undertaken by the Centre for Research and Technology Hellas (CERTH). He is a Member of IEEE and the Joint VTS & AES Greece Chapter and a member of Technical Chamber of Greece. Fotin-Niovi Pavlidou holds a Diploma and a Ph.D. in Telecommunications networks from the Aristotle University of Thessaloniki where she is currently engaged in teaching and research on Mobile Communications and Telecommunications Networks. Her research interests include traffic analysis and design of networks, performance evaluation and QoS studies of mobile satellite communications and multimedia applications over Internet. She is a permanent reviewer in IEEE journals, she has served as Guest-Editor of Special issues on “Ad-Hoc Networks”, “HAPs and applications”, “PLC Systems and Applications” for International Journals like IJWIN, WPC etc. She is the author of a Chapter on Fixed Access Techniques (TDMA/FDMA) in the Wiley Encyclopedia on Telecommunications (Editor:Prof. John Proakis), and of many editions of COST Actions on “Satellite Systems”, “Spread Spectrum Techniques” etc. She is the Delegate of Greece in the European COST Program on Telecommunications (1998–2004) and served as Chairperson for the COST262 Action “Spread Spectrum systems and techniques for wired and wireless Systems”. She is permanently included in the Program Committee of many IEEE conferences (PIMRC, GLOBECOM, VTC'2001, ISSSTA'2000) and she was the Chairperson of the IST Mobile Summit 2002, the annual conference of EU-Unit E4 in the field of Wireless Communications in Thessaloniki, June 16–20, 2002. She is involved in many European Projects (research or Education): Telematics Applications (INTERVUSE, ATTACH, etc.), IST (ISMAEL, B-Bone, SatNEx, OPERA, etc.), Tempus programs on Wireless Systems for Albania, Bulgaria, Poland. She is a Senior Member of IEEE (Communications and Vehicular Technology Society), currently chairing the Joint VTS & AES Greece Chapter.     

New Paradigms in Wireless Communication Systems

This paper discusses what a new paradigm can be in wireless communication systems of the twenty-first century. First, it suggests two directions for the new paradigm; one is “micro- and nano-device communication system” which is the projected scenario considering that the entities in source and destination have been shrinking throughout the history of wireless communication systems. The second direction is “networked robot system”, which emerges as a natural extension of mobile ad hoc networking where the networking is closely related to motion control of robots. Secondly, it shows two interesting research topics, “the new communication protocol design” and “signal processing”, respectively, that arise in the wake of the fusion between the two directions in the novel communication paradigm. Finally, it considers a new science of wireless communications in the twenty-first century. Shinsuke Hara received the B.Eng., M.Eng. and Ph.D. degrees in communications engineering from Osaka University, Osaka, Japan, in 1985, 1987 and 1990, respectively. From April 1990 to March 1997, he was an assistant professor in the Department of Communication Engineering, School of Engineering, Osaka University, and from October 1997 to September 2005, he was an associate professor in the Department of Electronic, Information and Energy Engineering, Graduate School of Engineering, Osaka University. Since October 2005, he has been a professor in the Department of Physical Electronics and Informatics, Graduate School of Engineering, Osaka City University. In addition, from April 1995 to March 1996, he was a visiting scientist at Telecommunications and Traffic Control Systems Group, Delft University of Technology, Delft, The Netherlands. His research interests include wireless communications systems and digital signal processing. Hiroyuki Yomo received B.S. degree in communication engineering from Department of Communication Engineering, Osaka University, Osaka, Japan, in 1997, and M.S. and Ph.D. degrees in communication engineering from Department of Electronic, Information, and Energy Engineering, Graduate School of Engineering, Osaka University, Osaka Japan, in 1999 and 2002, respectively. From April 2002 to March 2004, he was a Post-doctoral Fellow in Department of Communication Technology, Aalborg University, Denmark. From April 2004 to September 2004, he was at Internet System Laboratory, NEC Corporation, Japan. Since October 2004, he has been an Assistant Research Professor in Center for TeleInfrastructure (CTIF), Aalborg University, Denmark. His main research interests are access technologies, radio resource management, and link-layer techniques in the area of short-range communication, cellular network, cognitive radio, and sensor network. Petar Popovski received the Dipl.-Ing. in electrical engineering and M.Sc. in communication engineering from the Faculty of Electrical Engineering, Sts. Cyril and Methodius University, Skopje, Republic of Macedonia, in 1997 and 2000, respectively. He received a Ph.D. degree from Aalborg University, Denmark, in 2004. From 1998 to 2001 he was a teaching and research assistant at the Institute of Telecommunications, Faculty of Electrical Engineering in Skopje. He is currently Assistant Professor at the Department of Communication Technology at the Aalborg University. His research interests are related to the PHY-MAC aspects of wireless protocols, wireless sensor networks, random access protocols, and network coding. Kazunori Hayashi received the B.E., M.E. and Ph.D. degrees in communication engineering from Osaka University, Osaka, Japan, in 1997, 1999 and 2002, respectively. He spent 3 months in 2000 at Aalborg University, Denmark, as a Visiting Scholar. Since 2002, he has been with the Department of Systems Science, Graduate School of Informatics, Kyoto University. He is currently an Assistant Professor there. His research interests include digital signal processing for communications systems.     

Energy Efficiency of Error Control for High Data Rate WPAN

This paper addresses the issue of energy efficiency for error control mechanisms over WPAN systems. An analytical formulation has been developed to study the trade-off between link layer performance and energy consumption for two types of error control schemes: pure ARQ and type II hybrid ARQ protocol. An MC-CDMA-based system is considered. First of all, the analysis has been used to compare different error recovery schemes from the energy efficiency point of view. Moreover, it has been found that, for any channel conditions, there exists an optimal value of the transmit power that maximizes the energy efficiency. The paper also shows how this result can be used to design the power control of an energy efficient CDMA-based communication system. Mauro De Sanctis received the “Laurea' degree in Telecommunications Engineering from the University of Roma “Tor Vergata' in 2002. He is currently a Ph.D. Student and Assistant Professor in the Department of Electronics Engineering of the same University. He is involved in the DAVID (DAta and Video Interactive Distribution) satellite mission of the ASI (Italian Space Agency); his research is funded by the ASI. He is also involved in the MAGNET (My personal Adaptive Global NET) European FP6 integrated project and in the SatNEx European network of excellence. He worked on Italian national research projects on satellite-terrestrial systems integration such as SHINES (Satellite and HAP Integrated NEtworks and Services) and CABIS (CDMA for Broadband mobile terrestrial-satellite Integrated Systems). On autumn 2004 he joined the CTIF (Center for TeleInFrastructure), a research center focusing on modern telecommunications technologies located at the University of Aalborg (Denmark). His main areas of interest are: integration of different satellite networks, stratospheric platforms and terrestrial networks in a multi-layered fashion, internetworking and resource management in satellite systems and energy efficiency of WPAN systems. Simone Quaglieri received the “Laurea' degree cum laude in Telecommunications Engineering from the University of Roma “Tor Vergata', Italy, in 2004. His thesis, concerning the study of an analytic model for the Raman amplifier in optical systems with high bit rate, has been developed in the same University. During 2002 he worked as stagiaire on the design and development of optical submarine systems at the Elettra company (Telecom Italia group, Italy). He is joining the IRIS (Innovative Radio Integrated Systems) group at the University of Roma “Tor Vergata' as Research Engineer, where he is working on MC-CDMA based technology in the frame of the MAGNET (My Adaptive Global NETwork) European project. He is also working on error recovery mechanisms over satellite systems, and his research is funded by the EC in the frame of the SatNEx (Satellite Network of Excellence) European project. Ernestina Cianca graduated cum laude in Electronics Engineering in 1997 at the University of L'Aquila. She was with Italtel/Siemens (L'Aquila) from 1997 to 1998. She got her Ph.D. degree from the University of Rome Tor Vergata (URTV). The thesis work was on power management in CDMA-based satellite systems. She has been employed by the University of Aalborg, Denmark, in the Wireless Networking Groups (WING), as Research engineer (2000–2001) and as Assistant Professor (2001–2003). In particular, from Sept. 2002 she has been Technical Manager of Aalborg University for the IST-STRIKE project. She is currently Assistant Professor in Telecommunications at the URTV (Dpt. of Electronics Engineering), teaching DSP, Information and Coding. Her research mainly concerns wireless access technologies (CDMA and MIMO-OFDM-based systems), in particular, Radio Resource Management at PHY/MAC layer, ARQ/HARQ, TCP-IP issues over wireless links, integration of terrestrial and satellite systems. She has been the vice-coordinator of the following national research programs: CABIS, on CDMA integrated mobile systems (2000-2002) and SHINES, on satellite-HAP integrated networks for multimedia applications co-financed by MIUR (2002–2004). She is currently working on various European Projects: EU FP6 IP MAGNET (My personal Adaptive Global NET); EU ASIA LINK EAGER-NetWIC (Euro-Asian Network for Strengthening Graduate Education and Research in Wireless Communications); EU Network of excellence NEXWAY. She is author of about 40 papers, on international journals/transactions and proceedings of international conferences. Marina Ruggieri graduated in Electronics Engineering in 1984 at the University of Roma. She was: with FACE-ITT and GTC-ITT (Roanoke, VA) in the High Frequency Division (1985–1986); Research and Teaching Assistant at the University of Roma Tor Vergata (URTV) (1986–1991); Associate Professor in Telecommunications at the University of L'Aquila (1991–1994). Since November 2000 she is Full Professor in Telecommunications at the URTV (Dpt. of Electronics Engineering), teaching DSP, Information and Coding. In 1999 she has been appointed member of the Board of Governors of the IEEE AES Society (2000–2002) and re-elected for the period 2003–2005. Her research mainly concerns space communications and navigation systems (in particular satellites) as well as mobile and multimedia networks. She is the Principal Investigator of: satellite scientific communications missions (DAVID, WAVE) of ASI; national research programs (CABIS) on CDMA integrated mobile systems (2000–2002) and on satellite-HAP integrated networks for multimedia applications (SHINES), co-financed by MIUR (2002–2004). She co-ordinates the URTV Unit in various European Projects: EU FP6 IP MAGNET (My personal Adaptive Global NET); EU ASIA LINK EAGER-NetWIC (Euro-Asian Network for Strengthening Graduate Education and Research in Wireless Communications); EU Network of excellence NEXWAY; GALILEO JU 1st Call – July 2003: VERT (VEhicular Remote Tolling); and in the ASI program on V-band payloads (TRANSPONDERS). She is member of the Editorial Board of Wireless Personal Communications – an International Journal (Kluwer). She was awarded the 1990 Piero Fanti International Prize and she had a nomination for the Harry M. Mimmo Award in 1996 and the Cristoforo Colombo Award in 2002. She is author of about 170 papers, on international journals/transactions and proceedings of international conferences, book chapters and books.     

A Dynamic Priority MAC Protocol for Time-Bounded Services in Wireless Networks

Wireless Local Area Networks have gained popularity at an unprecedented rate over the last few years. However, as the spectrum of applications they are called to support broadens, their inefficiency in meeting the diverse requirements of a wider range of applications becomes evident. Most existing access mechanisms cannot provide Quality-of-Service (QoS) assurances. Even those that are QoS aware can only provide relative service differentiation. In this work, we propose a dynamic priority medium access scheme to provide time-bounded services. By approximating an ideal Earliest Deadline First (EDF) scheduler, the proposed scheme can offer delay and delay jitter assurances while achieving high medium utilization. Analytical studies and simulation experiments document and confirm the positive characteristics of the proposed mechanism. Orestis Tsigkas received his Diploma in electrical and computer engineering from the Aristotle University of Thessaloniki, Greece in 2002. He is currently working towards his Ph.D. degree in the same department. His research interests include medium access, as well as quality-of-service provisioning. Fotini-Niovi Pavlidou received the Ph.D. degree in electrical engineering from the Aristotle University of Thessaloniki, Greece, in 1988 and the Diploma in mechanical-electrical engineering in 1979 from the same institution. She is currently a Professor at the Department of Electrical and Computer Engineering at the Aristotle University engaged in teaching for the under- and post-graduate program in the areas of mobile communications and telecommunications networks. Her research interests are in the field of mobile and personal communications, satellite communications, multiple access systems, routing and traffic flow in networks and QoS studies for multimedia applications over the Internet. She is being involved with many national and international projects in these areas (Tempus, COST, Telematics,IST) and she has been chairing the European COST262 Action on “Spread Spectrum Systems and Techniques for Wired and Wireless Communications”. She has served as member of the TPC in many IEEE/IEE conferences and she has organized/chaired some conferences like, the “IST Mobile Summit 2002”, the 6th “International Symposium on Power Lines Communications-ISPLC2002”, the “International Conference on Communications-ICT1998” etc. She is a permanent reviewer for many IEEE/IEE journals. She has published about 80 papers in refereed journals and conferences. She has served as guest-editor on special issues as: “Mobile Ad Hoc Networks (MANETs): Standards, Research, Applications” in the International Journal of Wireless Information Networks and “Power Line Communications and Applications” in the International Journal on Communications Systems. She is a senior member of IEEE, currently chairing the joint IEEE VT&AES Chapter in Greece.     

The Future Re-Visited

The future of telecommunications is to reach mass population in all regions of the world with services that will benefit humankind leading to the betterment of its and all life in our planet. Telecommunications and its services have to and will become part of life as is breathing to mankind. This future is by far not achieved and for some time to come whatever we develop there is always a next step to it. After all, that keeps our world going.Currently we are again at that stage of work on future generation communications where these words have not yet achieved a consensus. In this paper let us look at the crystal ball and try to materialize at least in words what we see in it [1–20].We first define fourth generation (4G) communication system and beyond 3G (B3G). Then we look at the requirements for future generation communications from the perspective of the users, the operators, and the service providers. Next the technologies that should and are being developed to materialize the future generation are discussed. A dip is also taken into the ongoing standardization or pre-standardization efforts. At first the introduction section tries to raise questions on the “future”.Prof. Dr. Ramjee Prasad, while being a father always there for his children, is also a visionary and a leader in the field of telecommunications. It is with pride and honour that I write in this paper, on the occasion of 60th birthday of my father, my thoughts of the future of telecommunications. I owe to him and my mother the knowledge that I present and the future that I have written of. It is from the spark that they had put in me that this vision of future was created thus the title “the future re-visited”. Disclaimer: This paper reflects opinion of the author not of NTT DoCoMo or DoCoMo Euro-Labs. Anand Raghawa Prasad Senior Member IEEE, project manager network level security model group, DoCoMo Euro-Labs, Munich, Germany was born in Ranchi, India. He received his Ph.D. degree in the field of WLANs: protocols, security and deployment and MSc (Ir.) degree in the field of Self Similarity in ATM Network Traffic from Delft University of Technology, The Netherlands, in 2003 and 1996, respectively. From 1996 to 1998 he worked as research engineer and later project leader in Uniden Corporation, Tokyo, Japan. From 1998 to 2000, he was distinguished member of technical staff and worked as systems architect for IEEE 802.11 based WLANs (WaveLAN and ORiNOCO) in Lucent Technologies, Nieuwegein, The Netherlands. Subsequently, he was technical director at Genista Corporation, Tokyo, Japan, and technical advisor of PCOM:I3, Aalborg, Denmark. He was a voting member of IEEE 802.11 and he is an active participant of 3GPP. In addition to his publications in journals, international conferences and chapters in books, he has 20$+$ patent applications in the field of wireless communications and has co-edited a book titled “WLAN Systems and Wireless IP for Next Generation Communications” and co-authored a book on “Wireless LANs and Wireless IP: Security, Mobility, QoS and Mobile Network Integration” both published by Artech House in 2002 and 2005 respectively. He is writing a book on “Security in Wireless Networks and Mobile Platforms” to be published in August 2006. He has participated in organizing of various International Conferences including VTC, PIMRC and WPMC. He was a guest editor of a special issue on “Security for Next Generation Communications” of the Springer Journal on Wireless Personal Communications and he is a guest editor of a special issue on “Seamless Handover in Next Generation Wireless/Mobile Communications” of Wireless Personal Communications.     

Controlled sink mobility for prolonging wireless sensor networks lifetime

This paper demonstrates the advantages of using controlled mobility in wireless sensor networks (WSNs) for increasing their lifetime, i.e., the period of time the network is able to provide its intended functionalities. More specifically, for WSNs that comprise a large number of statically placed sensor nodes transmitting data to a collection point (the sink), we show that by controlling the sink movements we can obtain remarkable lifetime improvements. In order to determine sink movements, we first define a Mixed Integer Linear Programming (MILP) analytical model whose solution determines those sink routes that maximize network lifetime. Our contribution expands further by defining the first heuristics for controlled sink movements that are fully distributed and localized. Our Greedy Maximum Residual Energy (GMRE) heuristic moves the sink from its current location to a new site as if drawn toward the area where nodes have the highest residual energy. We also introduce a simple distributed mobility scheme (Random Movement or RM) according to which the sink moves uncontrolled and randomly throughout the network. The different mobility schemes are compared through extensive ns2-based simulations in networks with different nodes deployment, data routing protocols, and constraints on the sink movements. In all considered scenarios, we observe that moving the sink always increases network lifetime. In particular, our experiments show that controlling the mobility of the sink leads to remarkable improvements, which are as high as sixfold compared to having the sink statically (and optimally) placed, and as high as twofold compared to uncontrolled mobility. Stefano Basagni holds a Ph.D. in electrical engineering from the University of Texas at Dallas (December 2001) and a Ph.D. in computer science from the University of Milano, Italy (May 1998). He received his B.Sc. degree in computer science from the University of Pisa, Italy, in 1991. Since Winter 2002 he is on faculty at the Department of Electrical and Computer Engineering at Northeastern University, in Boston, MA. From August 2000 to January 2002 he was professor of computer science at the Department of Computer Science of the Erik Jonsson School of Engineering and Computer Science, The University of Texas at Dallas. Dr. Basagni’s current research interests concern research and implementation aspects of mobile networks and wireless communications systems, Bluetooth and sensor networking, definition and performance evaluation of network protocols and theoretical and practical aspects of distributed algorithms. Dr. Basagni has published over four dozens of referred technical papers and book chapters. He is also co-editor of two books. Dr. Basagni served as a guest editor of the special issue of the Journal on Special Topics in Mobile Networking and Applications (MONET) on Multipoint Communication in Wireless Mobile Networks, of the special issue on mobile ad hoc networks of the Wiley’s Interscience’s Wireless Communications & Mobile Networks journal, and of the Elsevier’s journal Algorithmica on algorithmic aspects of mobile computing and communications. Dr. Basagni serves as a member of the editorial board and of the technical program committee of ACM and IEEE journals and international conferences. He is a senior member of the ACM (including the ACM SIGMOBILE), senior member of the IEEE (Computer and Communication societies), and member of ASEE (American Society for Engineering Education). Alessio Carosi received the M.S. degree “summa cum laude” in Computer Science in 2004 from Rome University “La Sapienza.” He is currently a Ph.D. candidate in Computer Science at Rome University “La Sapienza.” His research interests include protocols for ad hoc and sensor networks, underwater systems and delay tolerant networking. Emanuel Melachrinoudis received the Ph.D. degree in industrial engineering and operations research from the University of Massachusetts, Amherst, MA. He is currently the Director of Industrial Engineering and Associate Chairman of the Department of Mechanical and Industrial Engineering at Northeastern University, Boston, MA. His research interests are in the areas of network optimization and multiple criteria optimization with applications to telecommunication networks, distribution networks, location and routing. He is a member of the Editorial Board of the International Journal of Operational Research. He has published in journals such as Management Science, Transportation Science, Networks, European Journal of Operational Research, Naval Research Logistics and IIE Transactions. Chiara Petrioli received the Laurea degree “summa cum laude” in computer science in 1993, and the Ph.D. degree in computer engineering in 1998, both from Rome University “La Sapienza,” Italy. She is currently Associate Professor with the Computer Science Department at Rome University “La Sapienza.” Her current work focuses on ad hoc and sensor networks, Delay Tolerant Networks, Personal Area Networks, Energy-conserving protocols, QoS in IP networks and Content Delivery Networks where she contributed around sixty papers published in prominent international journals and conferences. Prior to Rome University she was research associate at Politecnico di Milano and was working with the Italian Space agency (ASI) and Alenia Spazio. Dr. Petrioli was guest editor of the special issue on “Energy-conserving protocols in wireless Networks” of the ACM/Kluwer Journal on Special Topics in Mobile Networking and Applications (ACM MONET) and is associate editor of IEEE Transactions on Vehicular Technology, the ACM/Kluwer Wireless Networks journal, the Wiley InterScience Wireless Communications & Mobile Computing journal and the Elsevier Ad Hoc Networks journal. She has served in the organizing committee and technical program committee of several leading conferences in the area of networking and mobile computing including ACM Mobicom, ACM Mobihoc, IEEE ICC,IEEE Globecom. She is member of the steering committee of ACM Sensys and of the international conference on Mobile and Ubiquitous Systems: Networking and Services (Mobiquitous) and serves as member of the ACM SIGMOBILE executive committee. Dr. Petrioli was a Fulbright scholar. She is a senior member of IEEE and a member of ACM. Z. Maria Wang received her Bachelor degree in Electrical Engineering with the highest honor from Beijing Institute of Light Industry in China, her M.S. degree in Industrial Engineering/Operations Research from Dalhousie University, Canada and her Ph.D. in Industrial Engineering/Operations Research from Northeastern University, Boston. She served as a R&D Analyst for General Dynamics. Currently MS. Wang serves as an Optimization Analyst with Nomis Solutions, Inc.     

Fluid coding and coexistence in ultra wide band networks

Time Hopping Ultra Wide Band (TH–UWB) commonly encodes the data symbols by shifting the position of the transmitted pulses by a quantity that is quantized over the inter-pulse interval range. In this paper, we relax the hypothesis of a discrete value for the time shift introduced by the TH code, by considering the possibility of generating real-valued codes that introduce time hopping in a “fluid” way. The effect on the power spectral density of generated signals is analyzed, and application of fluid coding to multiple access and to network coexistence is investigated by simulation. Portions of this work were presented at the 2005 2nd International Workshop Networking with Ultra Wide Band, Workshop on Ultra Wide Band for Sensor Networks [M.G. Di Benedetto, G. Giancola, D. Domenicali and P. Ingargiola “Fluid Coding in Time Hopping Ultra Wide Band Networks,” Proceedings of the IEEE 2nd International Workshop Networking with Ultra Wide Band—Ultra Wide Band for Sensor Networks, July 2005, Rome, Italy]. Daniele Domenicali took his Laurea degree in Telecommunications Engineering at the University of Rome La Sapienza in 2004. In November 2004 Domenicali wins the open competition for PhD scholarship in Information and Communication Engineering. He is teaching assistant for the course of “UWB Communication Systems” conducted by Professor Maria Gabriella Di Benedetto at the University of Rome La Sapienza. His research activity includes Pulse Shaping and the related modulation and coding techniques (Time Hopping Coding, PAM and PPM Modulation). Particular attention is paid to the effects produced in the Power Spectral Density, in order to find solutions capable of optimizing spectrum occupation while meeting the constraints imposed by emission masks. Daniele Domenicali is involved in the European Network of Excellence HYCON (Hybrid Control: Taming Heterogeneity and Complexity of Networked Embedded Systems). Guerino Giancola received the “Laurea” degree (magna cum laude) in Telecommunications Engineering, and the Ph.D. degree in Information and Communication Engineering from University of Rome La Sapienza, in 2001 and 2005, respectively. He is currently a research affiliate at the INFOCOM Department at University of Rome La Sapienza, where is actually holding the course of “Electrical Communications” for the degree on Electronic Engineering. His research interests include the analysis and modelling of Multi User Interference in Impulse Radio systems, and the design of Medium Access Control functions and protocols for UWB ad-hoc networks. Guerino Giancola recently co-authored with Prof. Maria-Gabriella Di Benedetto a book on Ultra Wide Band from radio to the network, titled “Understanding Ultra Wide Band Radio Fundamentals” and published by Prentice Hall in June 2004. He is now involved in the European project “PULSERS – Pervasive Ultra wideband Low Spectral Energy Radio Systems” and in the European Network of Excellence “HYCON- Hybrid Control: Taming Heterogeneity and Complexity of Networked Embedded Systems”. Guerino Giancola is a member of the IEEE Communication Society. Maria-Gabriella Di Benedetto obtained her Ph.D. in Telecommunications in 1987 from the University of Rome La Sapienza, Italy. In 1991, she joined the Faculty of Engineering of University of Rome La Sapienza, where currently she is a Full Professor of Telecommunications at the Infocom Department. She has held visiting positions at the Massachusetts Institute of Technology, the University of California, Berkeley, and the University of Paris XI, France. In 1994, she received the Mac Kay Professorship award from the University of California, Berkeley. Her research interests include wireless communication systems and speech science. From 1995 to 2000, she directed four European projects for the design of UMTS. Since 2000, she has been active in fostering the development of Ultra Wide Band (UWB) radio communications in Europe. Within the 5th framework, she directed for the Infocom Dept. two European projects (whyless.com and UCAN) aimed at the design and implementation of UWB ad-hoc networks. Currently, within the 6th EU Framework, her “Networking with UWB” research group participates in the PULSERS Integrated Project which will integrate UWB research and development in Europe for the next years, and in the LIAISON Integrated Project as regards the application of UWB to location-based services. She also participates in the HYCON network of excellence. Dr. Di Benedetto is co-edited several Special Issues on UWB communications and networks for several Journals including IEEE JSAC, Journal of Communications and Networks, Mobile Networks and Applications, Eurasip. In 2004, Dr. Di Benedetto co-authored with G. Giancola the first published book on UWB for communications titled “Understanding Ultra Wide Band Radio Fundamentals” and published by Prentice Hall. She recently completed the co-edition of two new books on UWB that will be published by 2005: UWB Communication Systems - A comprehensive overview, with T. Kaiser, D. Porcino, A. Molisch, and I. Oppermann, Hindawi Publishing Corporation, 2005, andUltra Wideband Wireless Communications with H. Arslan and Z.N. Chen, John Wiley & Sons, Inc., 2005.     

Satellite Navigation and Communications: An Integrated Vision

The paper addresses advanced layered architectures for the development of integration scenarios between satellite navigation and communications systems and services. This synercic cooperation represents – in author's vision – the core of future global networks. The concept of integration and its translation into an integrated network is displayed, together with examples of possible architectures for navigation-communications applications. In this frame, the paper addresses also the possible exploitation of stratospheric platforms (HAP) as permanent and on-demand blocks concurring to the effective deployment of the integrated vision. Marina Ruggieri graduated in Electronics Engineering in 1984 at the University of Roma. She was: with FACE-ITT and GTC-ITT (Roanoke, VA) in the High Frequency Division (1985–1986); Research and Teaching Assistant at the University of Roma Tor Vergata (RTV) (1986–1991); Associate Professor in Telecommunications at Univ. of L'Aquila (1991–1994) and at the University of RTV (1994–2000). Since November 2000 she is Full Professor in Telecommunications at the RTV (Faculty of Engineering), teaching DSP, Information and Coding. Since 2003 she directs a Master in “Advanced Satellite Communications and Navigation Systems” at RTV.Since 1999 she has been appointed member of the Board of Governors of the IEEE AES Society.Her research mainly concerns space communications and navigation systems (in particular satellites) as well as mobile and multimedia networks.She is the Principal Investigator of satellite scientific communications missions (DAVID, WAVE) of ASI, national research programs (CABIS) on CDMA integrated mobile systems and on satellite-HAP integrated networks for multimedia applications (SHINES), co-financed by MIUR. She co-ordinates RTV Unit in various European Projects: EU FP6 IP MAGNET (My personal Adaptive Global NET); EU ASIA LINK EAGER-NetWIC (Euro-Asian Network for Strengthening Graduate Education and Research in Wireless Communications); EU Network NEXWAY; GALILEO JU 1st Call: VERT (VEhicular Remote Tolling); and in the ASI program on V-band payloads (TRANSPONDERS).She is Editor of the IEEE Transactions on AES for “Space Systems”, Chair of the IEEE AES Space Systems Panel. Since 2002, she is co-chair of Track 2 “Space Missions, Systems, and Architecture” of the AES Conference; she has been re-appointed in the IEEE Judith A. Resnik Award Committee for 2004; she has been member of TPC for PLANS 2004.She was awarded the 1990 Piero Fanti International Prize and she had a nomination for the Harry M.Mimmo Award in 1996 and the Cristoforo Colombo Award in 2002.She is author of about 220 papers, on international journals/transactions and proceedings of international conferences, book chapters and books.She is an IEEE Senior Member (S'84-M'85-SM'94).     

Decentralized Utility-based Sensor Network Design

Wireless sensor networks consist of energy-constrained sensor nodes operating unattended in highly dynamic environments. In this paper, we advocate a systematic decentralized approach towards the design of such networks based on utility functions. A local utility function is defined for each sensor node in the network. While each sensor node “selfishly” optimizes its own utility, the network as a “whole” converges to a desired global objective. For the purpose of demonstrating our approach, we consider the following two separate case studies for data gathering in sensor networks: (a) construction of a load balanced tree and (b) construction of an energy balanced tree. Our work suggests a significant departure from the existing view of sensor networks as consisting of cooperative nodes, i.e. “selfish”sensor nodes is a useful paradigm for designing efficient distributed algorithms for these networks. Narayanan Sadagopan received the B.S. degree in computer science from the Regional Engineering College, Trichy, India, in 1998, and the M.S. degree in computer science from University of Southern California (USC), Los Angeles, in 2001. He is currently working toward the Ph.D. degree in the Computer Science Department, USC. His research is focused on theoretical aspects of wireless ad hoc and sensor networks. Mitali Singh received the BTech. degree in Computer Science and Engineering from the Indian Institute of Technology, New Delhi, India in 2000, and the M.S. degree in Computer Science from the University of Southern California, Los Angeles, USA. She is currently working towards the Ph.D. degree in Computer Science at the University of Southern California. Her research interests lie in the area of applied theory and networks. Presently, her work is focused on high level modeling and distributed algorithm design for wireless sensor systems. Bhaskar Krishnamachari received the B.E.E.E. degree from The Cooper Union for the Advancement of Science and Art, New York, in 1998, and the M.S.E.E. and Ph.D. degrees in electrical engineering from Cornell University, Ithaca, NY, in 1999 and 2002, respectively. He is now an Assistant Professor in the Department of Electrical Engineering, University of Southern California, Los Angeles, where he also holds a joint appointment in the Department of Computer Science. His current research is focused on the discovery of fundamental principles and the analysis and design of protocols for next-generation wireless sensor networks.     

An Integrated AP for Seamless Interworking of Existing WMAN and WLAN Standards

Broadband Fixed Wireless Access (BFWA) systems represent a potential technological foundation for the Fourth Generation of Wireless Mobile Communication Systems (4G) as they can replace wired broadband and, with sufficient widespreading deployment, can significantly cut into the usage of cellular networks in many areas. In this context, the seamless interworking of Wireless Metropolitan Area Network (WMAN) and Wireless Local Area Network (WLAN) technologies is an efficient solution to provide the indoor extension of BFWA systems coverage, which would largely contribute to their success and penetration in the market. In this paper, we introduce a novel Access Point (AP), called WMAN/WLAN AP (WWAP), which essentially integrates in a compact device a WMAN Subscriber Station (SS) and a WLAN AP in order to extend the WMAN coverage in-house and to guarantee the end-to-end Quality of Service (QoS). Besides the technical features, the market trends and the usage scenarios where the WWAP might be a cost-effective and a very efficient solution are outlined. Finally, simulation results are carried out in order to demonstrate the effectiveness of the proposed AP. Simone Frattasi was born in Rome, Italy, on December 13, 1977. He received his B.Sc. and M.Sc. degrees from the University of Rome Tor Vergata, Italy, in 2001 and 2002, respectively. He has been employed by the University of Aalborg, Denmark, in the Wireless Networking Group (WING) as Research engineer (2002–2004), working on the IST-STRIKE (Spectrally Efficient Fixed Wireless Network based on Dual Standards) and VeRT (Vehicular Remote Tolling) projects. He is currently a Ph.D. student in the Center for TeleInFrastruktur (CTIF), Aalborg University, working on the JADE (Joint Advanced Development Enabling 4G) project, a joint cooperation of CTIF and SAMSUNG. His research interests mainly concern the Fourth Generation of Wireless Mobile Communication Systems (4G), in particular, heterogeneous services and architectures, clustering algorithms and MAC protocols related to the issues of cooperation and relaying in cellular extended short-range communication systems, hybrid and cooperative location techniques, QoS and ARQ/HARQ. Ernestina Cianca graduated cum laude in Electronics Engineering in 1997 at the University of L'Aquila. She was Italtel/Siemens (L'Aquila) from 1997 to 1998. She got her Ph.D. degree from the University of Rome Tor Vergata (URTV). The thesis work was on power management in CDMA-based satellite systems. She has been employed by the University of Aalborg, Denmark, in the Wireless Networking Group (WING), as Research engineer (2000–2001) and as Assistant Professor (2001–2003). She is currently Assistant Professor in Telecommunications at the URTV (Department of Electronics Engineering), teaching DSP, Information and Coding. Her research mainly concerns wireless access technologies (CDMA and MIMO-OFDM-based systems), in particular, Radio Resource Management at PHY/MAC layer, ARQ/HARQ, TCP-IP issues over wireless links, integration of terrestrial and satellite systems. She has been the vice-coordinator of the following national research programs: CABIS, on CDMA integrated mobile systems (2000–2002) and SHINES, on satellite-HAP integrated networks for multimedia applications co-financed by MIUR (2002–2004). She is currently working on various European Projects. She is author of about 40 papers, on international journals/transactions and proceedings of international conferences. Ramjee Prasad was born in Babhnaur (Gaya), Bihar, India, on July 1, 1946. He is now a Dutch Citizen. He received his B.Sc. (Eng) degree from Bihar Institute of Technology, Sindri, India, and his M.Sc. (Eng) and Ph.D. degrees from Birla Institute of Technology (BIT), Ranchi, India, in 1968, 1970 and 1979, respectively. Since June 1999, Dr. Prasad has been with Aalborg University, where currently he is Director of the Center for TeleInFrastruktur (CTIF), and holds the chair of wireless information and multimedia communications. He is the coordinator of the European Commission Sixth Framework Integrated Project MAGNET (My personal Adaptive Global NET). He was involved in the European ACTS project FRAMES (Future Radio Wideband Multiple Access Systems) as a DUT project leader. He is a project leader of several international, industrially funded projects. He has published over 500 technical papers, contributed to several books, and has authored, coauthored, and edited eleven books. He has served as a member of advisory and program committees of several IEEE international conferences. In addition, Dr. Prasad is the coordinating editor and editor-in-chief of the Kluwer International Journal on Wireless Personal Communications and a member of the editorial board of other international journals, including the IEEE Communications Magazine and IEE Electronics Communication Engineering Journal. Dr. Prasad is also the founding chairman of the European Center of Excellence in Telecommunications, known as HERMES. He is a fellow of IEE, a fellow of IETE, a senior member of IEEE, a member of The Netherlands Electronics and Radio Society (NERG), and a member of IDA (Engineering Society in Denmark). Dr. Prasad is the advisor of several multinational companies.     

Energy efficient routing with delay guarantee for sensor networks

The paper presents a routing algorithm that maximizes the lifetime of a sensor network in which all data packets are destined for a single collection node. Lifetime is maximized by adjusting the number of packets traversing each node. The adjustment is carried out by transmitting over alternative routes. The first part of the paper assumes that the worst case delay resulting from energy efficient routing is less than the maximum tolerable value. Ignoring the delay constraint of the network, the routes are selected as the solution to a linear programming (LP) problem in which the objective is to maximize the minimum lifetime of each node. The solution is implemented in a centralized algorithm, and then approximated by an iterative algorithm based on least cost path routing, in which each step is implemented efficiently in a distributed manner. The second part of the paper incorporates delay guarantee into energy efficient routing by constraining the length of the routing paths from each sensor node to the collection node. Simulations reveal that the lifetime of the network increases significantly by optimal routing, and including delay constraint in energy efficient routing improves the network performance since the delay of the network keeps increasing as the delay constraint is relaxed beyond the value at which the optimal lifetime is achieved. Research supported by National Science Foundation under Grant CMS-0408627 and California Department of Transportation. Sinem Coleri Ergen received the BS degree in electrical and electronics engineering from Bilkent University, Ankara, Turkey, in 2000, and the M.S. and Ph.D. degrees in electrical engineering and computer sciences from University of California Berkeley (UCB), in 2002 and 2005. Since January 2006, she has been a postdoctoral researcher in electrical engineering at UCB. Her research interests are in wireless communications and networking with a current focus on energy efficient system design for sensor networks. She is a member of the Sensor Networks for Traffic Monitoring project at UCB. She received Regents Fellowship from University of California Berkeley in 2000. Pravin Varaiya is Nortel Networks Distinguished Professor in the Department of Electrical Engineering and Computer Sciences at the University of California, Berkeley. From 1975 to 1992 he was also Professor of Economics at Berkeley. From 1994 to 1997 he was Director of the California PATH program, a multi-university research program dedicated to the solution of Californias transportation problems. His current research is concerned with communication networks, transportation, and hybrid systems. He has taught at MIT and the Federal University of Rio de Janeiro. Varaiya has held a Guggenheim Fellowship and a Miller Research Professorship. He received an Honorary Doctorate from LInstitut National Polytechnique de Toulouse, and the Field Medal of the IEEE Control Systems Society. He is a Fellow of IEEE and a member of the National Academy of Engineering. He is on the editorial board of several journals, including “Discrete Event Dynamical Systems” and “Transportation Research—C”. He has co-authored three books and more than 250 technical papers. The second edition of “High-Performance Communication Networks” (with Jean Walrand) was published by Morgan-Kaufmann in 2000. “Structure and interpretation of signals and systems" (with Edward Lee) was published by Addison-Wesley in 2003. Varaiya is a member of the Board of Directors of Sensys Networks.     

Access points vulnerabilities to DoS attacks in 802.11 networks

We describe possible denial of service attacks to access points in infrastructure wireless networks using the 802.11b protocol. To carry out such attacks, only commodity hardware and software components are required. The experimental results obtained on a large set of different access points show that serious vulnerabilities exist in any device we tested and that a single malicious station can easily hinder any legitimate communication within a basic service set. Francesco Ferreri graduated in Software Engineering in 2004 at Rome University “Tor Vergata”. He then joined CASPUR (Italian Interuniversities Consortium for Supercomputing Applications) where he led research activities involving wireless networks and IPv6 integration. He’s currently employed at NaMeX, Rome’s Internet Exchange Point, as a network and systems engineer. Leonardo Valcamonici graduated in Maths in 1994 at “La Sapienza” University in Rome. After that he joined CASPUR (Italian Interuniversities Consortium for Supercomputing Applications) where, in the beginning, he was involved in research activities in the field of parallel and distributed computing. After that he became a network and security engineer. He is now CASPUR’s Information Systems Security Officer and Network Applications and Services Team Leader.” Massimo Bernaschi graduated in physics in 1987 at “Tor Vergata” University in Rome. After that he joined the IBM European Center for Scientific and Engineering Computing (ECSEC) in Rome. He spent ten years with IBM working in the field of parallel and distributed computing. Currently he is with the Italian National Research Council (CNR) as chief technology officer of the Institute for Computing Applications. Moreover, he is an adjunct professor of Computer Science in “La Sapienza” University in Rome.     

Energy aware efficient geographic routing in lossy wireless sensor networks with environmental energy supply

Wireless sensor networks are characterized by multihop wireless lossy links and resource constrained nodes. Energy efficiency is a major concern in such networks. In this paper, we study Geographic Routing with Environmental Energy Supply (GREES) and propose two protocols, GREES-L and GREES-M, which combine geographic routing and energy efficient routing techniques and take into account the realistic lossy wireless channel condition and the renewal capability of environmental energy supply when making routing decisions. Simulation results show that GREESs are more energy efficient than the corresponding residual energy based protocols and geographic routing protocols without energy awareness. GREESs can maintain higher mean residual energy on nodes, and achieve better load balancing in terms of having smaller standard deviation of residual energy on nodes. Both GREES-L and GREES-M exhibit graceful degradation on end-to-end delay, but do not compromise the end-to-end throughput performance. Kai Zeng received his B.E. degree in Communication Engineering and M.E. degree in Communication and Information System both from Huazhong University of Science and Technology, China, in 2001 and 2004, respectively. He is currently a Ph.D. student in the Electrical and Computer Engineering department at Worcester Polytechnic Institute. His research interests are in the areas of wireless ad hoc and sensor networks with emphases on energy-efficient protocol, cross-layer design, routing, and network security. Kui Ren received his B. Eng. and M. Eng. both from Zhejiang University, China, in 1998 and 2001, respectively. He worked as a research assistant at Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences from March 2001 to January 2003, at Institute for Infocomm Research, Singapore from January 2003 to August 2003, and at Information and Communications University, South Korea from September 2003 to June 2004. Currently he is a PhD candidate in the ECE department at Worcester Polytechnic Institute. His research interests include ad hoc/sensor network security, wireless mesh network security, Internet security, and security and privacy in ubiquitous computing environments. Wenjing Lou is an assistant professor in the Electrical and Computer Engineering department at Worcester Polytechnic Institute. She obtained her Ph.D. degree in Electrical and Computer Engineering from University of Florida in 2003. She received the M.A.Sc. degree from Nanyang Technological University, Singapore, in 1998, the M.E. degree and the B.E. degree in Computer Science and Engineering from Xi’an Jiaotong University, China, in 1996 and 1993 respectively. From December 1997 to July 1999, she worked as a Research Engineer in Network Technology Research Center, Nanyang Technological University. Her current research interests are in the areas of ad hoc and sensor networks, with emphases on network and system security and routing. Patrick J. Moran received his MSEE from Carnegie Mellon University, 1993. He is currently the CTO and Founder of AirSprite Technologies Inc, and is driving the company to utilize advanced networking protocols for low-power wireless network systems. His interests include architecture, protocols and high performance implementation of emerging communication technologies. Patrick has been involved in deployment of communication and signal processing technologies since graduating from the University of Minn. in 1986. He holds several patents and publications relating to storage, medical and data processing information systems. He is a member of the IEEE.     

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

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

Wireless LANs Systems: An Advanced Resource Assignement Algorithm

The paper describes the design and simulation of a radio modem architecture, which provides wireless access to Internet in a single-hop, ad hoc network.The main emphasis is on the Medium Access Control (MAC) and Dynamic Link Control (DLC) layer’s design, and in particular on the adopted innovative scheduling algorithm, which has been developed to satisfy the system requirements of the WIND-FLEX radio modem. The algorithm is presented and compared to the Earliest Deadline First (EDF) solution.Several software simulation tests have been executed on the network, to test the performance of the system, in order to verify the capability of the scheduler algorithm to satisfy the expected requirements and the efficiency of the implemented solutions. Giuseppe Razzano was born in Roma, Italy, in 1974. He has graduated in Electronic Engineering “summa cum laude” and has received PhD in Communication Systems and Computer Science, in 2004 from University of Rome “La Sapienza”. From 2000 to 2001 he worked as research assistant at VTT electronics, in Finland. From 2004 to 2005 he worked as senior researcher at Forschungzentrum Telekommunikation Wien (Telecommunication Research Centre Vienna) in Austria. Currently, he works as System Engineer for Vitrociset S.p.A., working in a project funded by European Space Agency (ESA), for the development of a new generation space launcher vehicle (VEGA). In the past years, he worked in several projects funded by EC within the IST (Information Societies Technology) program, being also involved in projects in collaboration with Italian companies. His research is focused on resource management algorithms for wireless LANs and cellular networks. He is also interested in object-oriented programming and development methodologies. In these fields, he is author of several papers published in international journals and conferences. Francesco Delli Priscoli was born in Rome in 1962. He graduated in Electronic Engineering “summa cum laude” from the University of Rome “La Sapienza” in 1986. He received the Ph.D. in system engineering from the University of Rome “La Sapienza” in 1991. From 1986 to 1991 he worked in the “Studies and Experimentation” Department of Telespazio (Rome). Since 1991 he is working for the University of Rome “La Sapienza” where, at present, he is “Full Professor” and holds the courses “Automatic Controls”, “System Theory” and “Network Control and Management I and II”. In the framework of his activity, he researches in the nonlinear control theory and in the area of control-based resource management procedures for the third and forth generation of mobile systems. He is the author of about 150 technical papers on the above topics appeared on major international reviews (about 50) and conferences (about 100). In 2000 he has been scientific consultant for the Italian Council of Ministers in the framework of the auction for the assignment of the Italian Universal Mobile Telecommunication System (UMTS) licensees. He is an associate editor of Control Engineering Practice and a member of the IFAC Technical Committee on “Networked Systems”. He is/has been scientific responsible, for the University of Rome “La Sapienza”, of 17 projects financed by the European Union (fourth, fifth and sixth framework programmes) or by the European Space Agency (ESA), dealing with resource management for UMTS and broadband terrestrial and satellite wireless systems. He is also a project evaluator for the European Commission. Roberto Cusani received the “laurea” degree in Electronic Engineering (cum laude) and the Ph.D. in Communication Systems and Computer Science from the University of Rome “La Sapienza”. From 1986 to 1990 he was research engineer at the University of Rome “Tor Vergata”, teaching Digital Signal Processing. In 1991 he joined the University of Rome “La Sapienza” as Associate Professor of Signal Theory. In 2000 he becomes Full Professor and teaches Information Theory and Coding, and Mobile Communications. His former research activities concern transmission and coding of signals and images, with emphasis on random processes, spectral estimation and image coding. Since 1992 he focused his activities in the field of the digital communication systems, with emphasis on channel equalisation and coding for HF and radio-mobile (GSM) links, on the design of CDMA receivers for UMTS and, in general, on the use of digital techniques within telecommunication equipments. More recently his interests also includes the study of MAC (Multiple Access Control) protocols with application to wireless area networks (WLANs), reconfigurable ad-hoc networks and satellite links. He is author of more than 100 publications in international journals and conferences, of the text-book “Teoria dei Segnali” and of five patents regarding telecommunication applications. He was involved in many research programs, both national and international, and in projects with the industrie.     

Energy efficient node-to-node authentication and communication confidentiality in wireless sensor networks

A distributed Wireless Sensor Network (WSN) is a collection of low-end devices with wireless message exchange capabilities. Due to the scarcity of hardware resources, the lack of network infrastructures, and the threats to security, implementing secure pair-wise communications among any pair of sensors is a challenging problem in distributed WSNs. In particular, memory and energy consumption as well as resilience to sensor physical compromise are the most stringent requirements. In this paper, we introduce a new threat model to communications confidentiality in WSNs, the smart attacker model. Under this new, more realistic model, the security features of previously proposed schemes decrease drastically. We then describe a novel pseudo-random key pre-deployment strategy ESP that combines all the following properties: (a) it supports an energy-efficient key discovery phase requiring no communications; (b) it provides node to node authentication; (c) it is highly resistant to the smart attacker.We provide both asymptotic results and extensive simulations of the schemes that are beingproposed. This work was partially funded by the WEB-MINDS project supported by the Italian MIUR under the FIRB program, and by the PRIN 2003 “Web-based Management and Representation of Spatial and Geographic Data” program from the Italian MIUR. Roberto Di Pietro is partially funded by ISTI-CNR, WNLab, Pisa, with a Post-doc grant under the IS-MANET program. Roberto Di Pietro received the Ph.D. in Computer Science from the University of Roma “La Sapienza”, Italy, in 2004. He received the Bs. and Ms. degree in Computer Science from the University of Pisa, Italy, in 1994. Since 1995 he has been working for the technical branch of the Italian Army and the Internal Affairs Ministry. His main research interests include: security for mobile ad hoc and wireless networks, security for distributed systems, secure multicast, applied cryptography and computer forensics. Luigi V. Mancini received the PhD degre in Computer Science from the University of Newcastle upon Tyne, UK, in 1989, and the Laurea degree in Computer Science from the University of Pisa, Italy, in 1983. From 2000, he is a full professor of Computer Science at the Dipartimento di Informatica of the University of Rome “La Sapienza”. Since 1994, he is a visiting research professor of the Center for Secure Information Systems, GMU, Virginia, USA. Currently he is the advisor of six Ph.D students. His current research interests include: computer network and information security, wireless network security, fault-tolerant distributed systems, large-scale peer-to-peer systems, and hard-real-time distributed systems. He published more than 60 scientific papers in international conferences and journals such as: ACM TISSEC, IEEE TKDE, IEEE TPDS, and IEEE TSE. He served in the program committees of several international conferences which include: ACM Conference on Computer and Communication Security, ACM Conference on Conceptual Modeling, ACM Symposium on Access Control Models and Technology, ACM Workshop of Security of Ad-hoc and Sensor Networks, IEEE Securecomm, IEEE Conference on Cluster Computing. He is also the program chair of the first two editions of the IEEE Workshop on Hot Topics in Peer-to-Peer Systems held in 2004 (Volendam, Holand) and in 2005 (San Diego, California). Currently, he is a member of the Scientific Board of the Italian Communication Police force, and the director of the Master degree program in Computer and Network Security of the University of Rome “La Sapienza”, Italy. Alessandro Mei received the Laurea degree in computer science from the University of Pisa, Italy, in 1994, and the PhD degree in mathematics from the University of Trento, Italy, in 1999. In 1998, he was at the Department of EE-Systems of the University of Southern California, Los Angeles, as a visiting scholar for one year. After holding a postdoctoral position at the University of Trento, in 2001 he joined the Faculty of Science of the University of Rome "La Sapienza", Italy, as an assistant professor of computer science. His main research interests include security of distributed systems and networks, algorithms for parallel, distributed, and optical systems and reconfigurable computing. He was presented with the Best Paper Award of the 16th IEEE International Parallel and Distributed Processing Symposium in 2002, the EE-Systems Outstanding Research Paper Award of the University of Southern California for 2000, and the Outstanding Paper Award of the Fifth IEEE/ACM International Conference on High Performance Computing in 1998. He is a member of the ACM and the IEEE and, from 2005, he is an Associate Editor of IEEE Transactions on Computers.