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.     

(UWB)<Superscript>2</Superscript>: Uncoordinated,Wireless, Baseborn Medium Access for UWB Communication Networks

A MAC protocol for Ultra Wide Band (UWB) radio networks named (UWB)² is proposed. The algorithm exploits typical features of impulse radio such as large processing gain, and is conceived in conjunction with a synchronization strategy which foresees the presence of a synchronization sequence in each transmitted packet. (UWB)² adopts a pure Aloha approach; Performance analysis of the synchronization tracking mechanism showed in fact that under the preliminary simplistic hypothesis of an AWGN channel, and for a sufficient number of pulses in the synchronization sequence, a fairly high probability of successful synchronization can be achieved, even in the presence of several users and Multi User Interference (MUI). The multiple access scheme is based on the combination of a common control channel provided by a common Time Hopping (TH) code with dedicated data channels associated to transmitter specific TH codes.Results obtained by simulation indicate that (UWB)² can be successfully applied when the number of users spans from a few tens to about one hundred, for data rates ranging from a few thousands to a few hundreds of bits per second. Network throughput was above 99.8% in all considered simulation settings. Such achievement confirms that (UWB)² is a suitable and straightforward solution for large networks of terminals using impulse radio for transmission at low bit rates.On leave from the Institut für Elektro- und Informationstechnik, College of Engineering, University of Duisburg-Essen, Duisburg, Germany.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 speech analysis and synthesis, and digital communication systems. 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 directs for the Infocom Dept. two European projects (whyless.com and UCAN) aimed at the design and implementation of UWB ad-hoc networks. 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 currently also participates in the HYCON network of excellence. Dr. Di Benedetto is co-editor for the IEEE JSAC Special Issue on UWB Radio in Multi-Access Wireless Communications (December 2002)and for the Journal of Communications and Networks Special Issue on Ultra-Wideband Communications (December 2003). Dr. Di Benedetto recently co-authored with Guerino Giancola a book on Ultra Wide Band from radio to the network, titled “Understanding Ultra Wide Band Radio Fundamentals” and published by Prentice Hall in May 2004.Luca De Nardis received his “Laurea” degree in telecommunications engineering from the University of Rome La Sapienza in 2001 with a thesis on wireless network topologies in the framework of the European project whyless.com. He is now pursuing a Ph.D. in Information and Communication Theory in the INFOCOM Department of the University of Rome. Since 2002, he has been participating in the European IST project UCAN, dealing with application of UWB radio to ad-hoc networking. Currently, he is involved in the 6th Framework European projects PULSERS and LIAISON. His research focuses on UWB technology, ad-hoc communication networks organization, Medium Access Control and routing protocols for wireless networks.Matthias Junk was born in Oberhausen, Germany, in 1978. From 1997 to 2004 he studied electrical engineering with main subject communications at the University of Duisburg-Essen, Germany. In 2004 he received his diploma. During his diploma thesis at the University “La Sapienza” in Rome, Italy, he focused on synchronization problems in Ultrawideband Communication Networks.Guerino Giancola received the Laurea degree (magna cum laude) in Telecommunications Engineering from the University of Rome La Sapienza, Italy, 2001, with a thesis on the analysis and the modelling of electromagnetic propagation in outdoor urban scenarios for mobile radio communications systems. Currently, he is working toward the Ph.D. degree in Information and Communication Theory in the INFOCOM Department of the University of Rome La Sapienza. His research interests include Ultra Wide Band radio technology, multi-carrier transmission techniques, and Medium Access Control protocols. From 2001 to 2002, he participated in a national research project financed by the Italian Ministry for University and Scientific-Technological Research (MURST), project PRIN2000: “OFDM Systems for Applications in the Wireless LANs.” Since 2002, he participates in two European Union research projects within the International Society Technologies program (IST): project No. IST-2001-32710: “Ultra-wideband Concepts for Ad-hoc Networks (UCAN)”, and project No. IST-2000-25197: “Whyless.com-The Open Mobile Access Networks.” From 2003, he also participates in the national research project financed by the Italian Ministry for University and Research (MIUR), project FIRB: VICOM-Virtual Immersive COMmunications.     

Programmable CNN Analogue Chip for RD-PDE Multi-Method Simulations

Cellular Non Linear Networks can be useful applied for the solution of several types of Partial Differential Equations (PDEs). This paper will describe an analogue circuit implementation for the simulation of one-dimensional Reaction-Diffusion PDE with the possibility to set different boundary conditions as well as to select different discretization methodologies. Fausto Sargeni was born in Riano (ROMA) in 1961. He received the Dipl. Eng. degree in Electronic Engineering at the University of Rome “La Sapienza" in 1987. In 1989 he jointed the Dept. of Electronic Engineering at the University of Rome “Tor Vergata" as Assistant Professor. In 1998 he became Associate Professor. His research interests include analog VLSI circuits for non linear circuits and high-speed interconnections. Vincenzo Bonaiuto was born in Rome, Italy, in 1962. He received the Dipl. Eng. degree in Electronic Engineering at the University of Rome “La Sapienza". In 1997 he received the the Ph.D. in Telecommunication and Microelectronics. In 1996 he jointed the Electronic Engineering Dept. as Assistant Professor at the University of Rome “Tor Vergata” and, in 2002, he became Associate Professor. His main research interests are in the area of non linear circuits, Artificial Neural Networks analogue/digital VLSI circuits implementation.     

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.     

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.     

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.     

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.     

Ultra Wide Band WLANs: A Self-Configuring Resource Control Scheme for Accessing UWB Hot-Spots with QoS Guarantees

In the framework of wireless access networks the Hot-Spot concept is attracting several operators. In a Hot-Spot near stationary terminals may reach one or more Radio Access Points (RAP) offering wireless access to the fixed network. Mobile terminals should be able to register to the network, associate to a RAP and activate a wireless communication supporting given bit rates and Quality of Service (QoS) features. Several mobile users, requiring different services, enter and exit the Hot-Spot. In this scenario network operators should have the opportunity to configure quickly radio resources to serve the mobile terminals and to handle efficiently the network resources in order to maximize the income. Among the different technologies emerging in this field, we investigate the feasibility of a wireless access based on Ultra Wide Band (UWB) radio, combined with a flexible admission control scheme based on transmission power selection. We employ UWB in unlicensed mode, i.e., we operate in accordance to the limits imposed by the regulatory bodies (e.g., US Federal Communications Commission). The flexibility of the admission control depends mainly on the capability of a mobile terminal of “measuring” the environment it is entering and thus supporting the RAP in the selection of the appropriate transmission parameters. The proposed approach provides an admission policy based on the Maximum Extra Interference (MEI) and selects the power level through a simple interaction among the involved mobile terminals. The information for basing the decision on is collected through measurements and signaling. In order to increase the system efficiency, transmission parameters are selected in accordance to a “balancing” criterion (thus Balanced-MEI, B-MEI). The B-MEI approach keeps quite simple the admission of new mobile terminals in a RAP’s area but contemporarily satisfies the trade-off between fair resource assignment and system efficiency. This is a key trade-off in wireless access systems where interference effects determine the upper limit of the number of users that can be admitted in the network.Francesca Cuomo received her “Laurea” degree in Electrical and Electronic Engineering in 1993, magna cum laude, from the University of Rome “La Sapienza”, Italy. She earned the Ph.D. degree in Information and Communications Engineering in 1998, also from the University of Rome “La Sapienza.” Since 1996 she is an Assistant Professor at the INFOCOM Department of this University. Her main research interests focus on broadband integrated networks, Intelligent Networks, architectures and protocol for wireless networks, mobile and personal communications, Quality of Service guarantees and real time service support in the wired and wireless Internet.She participated in: (I) the European ACTS INSIGNIA project dedicated to the definition of an Integrated IN and B-ISDN network; (III) IST WHYLESS.COM project focusing on adoption of the Ultra Wide Band radio technology for the definition of an Open Mobile Access Network; (III) RAMON project, funded by the Italian Public Education Ministry, focused on the definition of a reconfigurable access module for mobile computing applications. She is now participating to the European IST ePerSpace Project focusing on the support of personalized audio/video services at home and everywhere. She is also involved in FIRB project VIRTUAL IMMERSIVE COMMUNICATIONS (VICOM) where she is responsible of the research activities on the BAN and PAN networks.Dr. Cuomo is in the editorial board of the Elsevier Computer Networks journal and she has served on technical program committees and reviewer in several international conferences and journals including ACM Wireless Mobile Internet Workshop, IEEE ICC and GLOBECOM, IEEE Trans. on Wireless Communications and IEEE Journal on Selected Areas on Communications.Cristina Martello received her Laurea degree in Electronic Engineering (magna cum laude) in July 2000 from Università di Roma “La Sapienza”. She earned the PhD degree in Information and Communications Engineering in February 2004 (Università di Roma “La Sapienza”).Since January 2001 she has been working in the IST European HYPERLINK “/” “_blank” Whyless.com project on an open mobile access network based on the Ultra Wide Band radio technology. She collaborated with HYPERLINK “http://www.coritel.it/” “_blank” Co.Ri.Tel. (a research consortium on Telecommunications) as a fellowship holder in 2000/2001 for the project SWAP on the feasibility of a re-configurable software module for the dynamic Radio Resource Control in the 3G of mobile wireless systems, and in 2002 for the project PRESTO.Her main research interests regard the developing of flexible and distributed Radio Resource Control techniques for “ad-hoc like” networking paradigms.     

Input-Matching and Offset-Cancelling Networks for Limiting Amplifiers in Optical Communication Systems

The diffusion of optical communication systems in the access network and for short-haul datacom applications requires the use of low-cost plastic packages: the functional block most affected is the limiting amplifier, that is often the first stage of the Clock and Data Recovery (CDR) IC. In this paper we illustrate the design issues of the input-matching and offset-cancelling network for a differential limiting amplifier for optical communication systems, with particular emphasis on the effect of bond wires. We discuss the limitations of passive feedback networks when used both for offset suppression and for input matching, and propose a topology that overcomes such limitations by using an active feedback loop. A 50 Ω-loaded differential pair is used to achieve input matching and high offset suppression, and its buffering action desensitizes the input matching from the effect of the bond wires connecting off-chip filtering capacitors. Very good performance even with low cost plastic packages can be achieved by solving the trade-off between power consumption, offset suppression and the value of the low-pass filtering capacitors. Design examples of CDR IC's for 2.5 Gb/s optical systems are presented to compare the proposed topology with solutions based on passive feedback networks. Marco Balsi received the laurea (M.Sc.) degree in 1991 and the dottorato di ricerca (Ph.D.) in 1995 in Electronic Engineering from University of Roma “La Sapienza”, Roma, Italy. Since 1996 he is with “La Sapienza” University as ricercatore (assistant professor). He is engaged in research in nonlinear and soft-computing-based signal processing (especially for biomedical imaging), artificial vision, mechatronics, and anti-personnel mine detection. He has published about 60 paper in international journals and refereed conferences. Francesco Centurelli received the laurea degree (cum laude) and the Ph.D. degree in electronic engineering from the University of Roma “La Sapienza”, Roma, Italy, in 1995 and 2000, respectively. He is currently doing postdoctoral work with the Electronic Engineering Department of the University of Roma “La Sapienza.” His research interests include system-level analysis and design of clock recovery circuits and high-speed analog integrated circuits, with particular emphasis on gigabit-rate optical communication systems. Andrea Pallotta received the M.S. degree in electronic engineering from the University of Ancona, Ancona, Italy. From 1991 to 1999, he was with Italtel, Italy, where he joined several European Community research projects in the field of SDH and WDM fiber-optic transmission systems for both transport and access networks. From 1999 to 2000, he was with Siemens Information and Communication Networks, where he was responsible for the SDH Cross-Connect advanced development group. In September 2000, he joined the STMicroelectronics Company, where he is currently responsible for the electrooptical interface design group. His research interests include GaAs and silicon high-speed ICs, active optical devices, high-speed TX and RX optical modules, and fiber-optic transmission system engineering. Alessandro Trifiletti was born in Roma, Italy, in 1959. In 1991, he joined the Electronic Engineering Department of the University of Roma “La Sapienza” as a Research Assistant and is currently an Assistant Professor. His research interests include high-speed circuit design techniques and III-V device modeling.     

An Integrated Medium Access Control and Traffic Management Architecture for DVB-RCS SkyplexNet Satellite Systems

The growing development of standard Internet services and the emerging exploitation of several broadband multimedia contents disclosing in the last years, significantly promoted scenarios where Satellite Networks can play key roles. Several satellite networks are currently implemented according to the Digital Video Broadcasting-Return Channel via Satellite (DVB-RCS) standard, assuming to operate with a transparent satellite and an hub-centric (star) network topology. The present work addresses the SkyplexNet (SKN) system: an advanced Broadband Satellite Network for meshed connectivity developed by Alenia Spazio, within the framework of ESA Artes 3 – Line 1 Program, according to the DVB-RCS standard with duly extensions for the on-Board multiplexing capability of the Skyplex Units currently embarked on HotBird VI and W3A satellites. In this paper an architecture design study aiming at integrating the Medium Access Control (MAC) and Traffic Management (TM) functionality in a DVB-RCS like Network is presented. The envisaged Traffic Management schemes shall enable the SKN System to guarantee an adequate support of various Quality of Service (QoS) requirements and their application according to pre-defined Traffic Profiles established at connection set up phase with the support of physical medium access management functions. The functional architectures studied for the SKN Inter-Working Layer, from Internet protocols to SkyplexNet ones, and the SKN MAC layer have been also analysed on the interoperability level of these layers in order to deploy such functions as SKN connection mapping, packet scheduling and Bandwidth on Demand (BoD) policies. In this paper two different schemes of Traffic Management and MAC are presented reporting a detailed analysis of advantages and drawbacks of both approaches to be taken into account for future SkyplexNet system implementations. Fabrizio Di Cola is a Network and System Engineer of the Telecommunication Mission Unit of Alenia Spazio company (Italy). He received the M.S. degree in Telecommunication Engineering from University of Rome “La Sapienza” in 1998 and he is in Alenia Spazio since 2000. He is currently involved in the design and deployment of the Ground Segment of EuroSkyWay and SkyplexNet satellite systems as responsible for the Satellite User terminals Design and Development. He also contributes to System Engineering in the framework of several ESA and EC projects. From 1999 up to 2000, he worked as Researcher in the University of Bradford (Bradford, UK), Telecommunication Research Centre, within the “Satellite Mobile Group”. His activity focused on several aspects of the Mobility Management within telecommunications network integrating satellite and terrestrial networks. Emiliano Micaloni was born in Rome, Italy, in 1977. He is a Junior Telecommunication System Engineer involved since 2003 in a collaboration between University of Rome “La Sapienza” and the TLC Mission Unit of Alenia Spazio company (Italy). He received his Master Degree in Electronic Engineering from the University of Rome “La Sapienza”, Italy, in 2002, defending a thesis on Connection and Congestion Control for Geostationary Satellite Networks. Currently his area of interest concerns the Medium Access Control in the SkyplexNet Satellite Network, also contributing at the development activities for the SkyplexNet Satellite Terminals. In 2002–03 he collaborated with the “Computer Science and Systems” Department of “La Sapienza“ implementing solutions for Traffic Management and Quality of Service in Satellite Networks. All his activities are carried out in the framework of different ESA and EU IST projects. Luigi Secondiani received his M.S. degree in Telecommunication Engineering from University of Rome “La Sapienza” in 1997. From 1998 to 1999 he received a post-degree grant issued by the “Infocom” Department of the University of Rome “La Sapienza” in the frame of the ACTS 4th framework programme. Since December 1999 he works as a Network Engineer in Alenia Spazio-TLC Mission Unit, and he is currently involved in Alenia's activities on EC, ESA and NATO programmes. His main research interests mainly lie on interworking between Next Generation Satellite Systems (NGSS) and IP networks, with particular emphasis on network architectures, terminal's architectures and routing issues. Giuseppe Tomasicchio is a Senior Telecommunication System Engineer of the TLC Mission Unit of Alenia Spazio company (Italy). He received his degree in 1989 from University of Bari (Italy) in the Artificial Intelligence field. He received a Post-degree Diploma on Technologies of Educational Communication in 1991 and a Post-degree Engineering Specialisation Diploma in Signal Processing in 1994 from University of Bari. Currently he is responsible of the Ground System Design of EuroSkyWay/SkyplexNet satellite systems and of the Network Operations and Service Centres engineering in satellite networks devoted to multimedia applications in the framework of different ESA and EC projects. In 1997–98 he was responsible at CERN (Geneva, Switzerland) of the Data Acquisition System involving the readout, calibration, event display and the networking setup tasks of high energy physics experiments. From 1994 to 1998 he was at INFN (Italian Institute for Nuclear Physics) as researcher. In 1994 he was an IS-specialist in the Italian Government data processing centre and collaborated with the Government Seismic Service for GIS processing. He worked in 1991–92 as a fellow of DIGITAL Corporation for a join research activity at INFN in the field of Image processing and Pattern recognition applied to raw-data images produced from detectors in high energy physics experiments at CERN. He is author of several scientific and engineering papers.     

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.     

Tightening the upper bound for the minimum energy broadcasting

In this paper we present a new upper bound on the approximation ratio of the Minimum Spanning Tree heuristic for the basic problem on Ad-Hoc Networks given by the Minimum Energy Broadcast Routing (MEBR). We introduce a new analysis allowing to establish a 6.33-approximation ratio in the 2-dimensional case, thus decreasing the previously known 7.6 upper bound [4], almost closing the gap with the lower bound of 6 [12]. Preliminary results concerning this paper appeared in [9]. Michele Flammini received the degree in Computer Science at the University of L’Aquila in 1990 and the Ph.D. degree in Computer Science at the University of Rome “La Sapienza” in 1995. He is full professor at the Computer Science Department of the University of L’Aquila since March 2005. His research interests include algorithms and computational complexity, game theory, communication problems in interconnection networks and routing. He has authored and co-authored more than 70 papers in his fields of interest published in the most reputed international conferences and journals. Ralf Klasing received the PhD degree from the University of Paderborn in 1995. From 1995 to 1997, he was an Assistant Professor at the University of Kiel. From 1997 to 1998, he was a Research Fellow at the University of Warwick. From 1998 to 2000, he was an Assistant Professor at RWTH Aachen. From 2000 to 2002, he was a Lecturer at King’s College London. In 2002, he joined the CNRS as a permanent researcher. From 2002 to 2005, he was affiliated to the laboratory I3S in Sophia Antipolis. Currently, he is affiliated to the laboratory LaBRI in Bordeaux. He has co-authored a Springer Monograph, a book chapter, and has published more than 40 papers in refereed international periodicals. His research interests include Communication Algorithms in Networks, Approximation Algorithms for Combinatorially Hard Problems, Web Graphs and Web Algorithms, and Optimization Problems in Ad-Hoc Wireless Networks. Alfredo Navarra received the degree in Computer Science at the University of L’Aquila in 2000 and the Ph.D. degree in Computer Science at the University of Rome “La Sapienza” in 2004. From 2003 to 2004, he joined the MASCOTTE project team at the INRIA institute of Sophia Antipolis as PhD student and PostDoc for almost two years. In 2005, he was a temporary researcher at the University of L’Aquila. In 2006, he joined the laboratory LaBRI in Bordeaux as PostDoc. His research interests include, algorithms and computational complexity, communication, modelling as well as analysis and experimentation problems on protocols and routing algorithms for interconnaction networks such as Ad Hoc, Wireless, Mobile and Sensor Networks. He has authored and co-authored more than 25 papers in his fields of interest published in the most reputed international conferences and journals. Stéphane Pérennes is a permanent researcher of the French Centre National de la Recherche Scientifique (CNRS). He is affiliated to the MASCOTTE project team at the Institut National de Recherche en Informatique et Automatique (INRIA) of Sophia Antipolis. He has authored and co-authored more than 70 papers in his fields of interest that vary from pure theoretical to applied issues on algorithms and complexity, networking and routing.     

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.     

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.     

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).     

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.     

A Comparative Evaluation of Designs for Reliable Memory Systems

This paper addresses the design of storage systems for operation under critical environmental conditions. For these applications, these systems should have low latency time in access, high performance in throughput and high storage capabilities; therefore, they must be assembled using highly reliable components, while allowing flexibility in design. Commercial Off The Shelf (COTS) components have often been used. A COTS-based architecture is analyzed in this paper; the proposed architecture uses design-level techniques (such as error detection/correction codes and scrubbing) to make commercially available Dynamic Random Access Memory (DRAM) chips tolerant to faults. This paper provides a complete and novel analysis of engineering alternatives which arise in the design of a highly reliable memory system based on Reed Solomon coding. A comparative analysis of methods for permanent fault detection is provided; moreover using a Markovian characterization, different functional arrangements (based on code and scrubbing frequency) are investigated and evaluated.Gian Carlo Cardarilli received the Laurea (summa cum laude) in 1981 from the University of Rome La Sapienza. He works for the University of Rome Tor Vergata since 1984. At present he is full professor of Digital Electronics and Electronics for Communication Systems at the University of Rome Tor Vergata. During the years 1992–1994 he worked for the University of L Aquila. During the years 1987/1988 he worked for the Circuits and Systems team at EPFL of Lausanne (Switzerland). Professor Cardarilli interests is in the area of VLSI architectures for Signal Processing and IC design. In this field he published over 140 papers in international journals and conferences. He also participated to the work group of JESSI-SMI for the support to the medium and small industries. For this structure he consulted different SMIs, designing a number ASICs, in order to introduce the microelectronics technology in the industry’s products. He has also regular cooperation with companies like Alenia Aerospazio, Rome, Italy, STM, Agrate Brianza, Italy, Micron, Avezzano, Italy, Ericsson Lab, Rome, Italy and with a lot of SMEs. Scientific interests of Professor Cardarilli concern the design of special architectures for signal processing. In particular, he works in the field of computer arithmetic and its application to the design of fast signal digital processor. He also developed mixed-signal neural network architectures implementing them in silicon technology. Recently, he also proposed different new solutions for the implementation of fault-tolerant architectures.Fabrizio Lombardi graduated in 1977 from the University of Essex (UK) with a B.Sc. (Hons.) in Electronic Engineering. In 1977 he joined the Microwave Research Unit at University College London, where he received the Master in Microwaves and Modern Optics (1978), the Diploma in Microwave Engineering (1978) and the Ph.D. from the University of London in 1982.He is currently the holder of the International Test Conference (ITC) Endowed Professorship at Northeastern University, Boston. At the same Institution during the period 1998–2004 he served as Chair of the Department of Electrical and Computer Engineering. Prior to Northeastern University he was a faculty member at Texas Tech University, the University of Colorado-Boulder and Texas A&M University.Dr. Lombardi has received many professional awards: the Visiting Fellowship at the British Columbia Advanced System Institute, University of Victoria, Canada (1988), twice the Texas Experimental Engineering Station Research Fellowship (1991–1992, 1997–1998) the Halliburton Professorship (1995), the Outstanding Engineering Research award at Northeastern University (2004) and an International Research award from the Ministry of Science and Education of Japan (1993–1999). Dr. Lombardi was the recipient of the 1985/86 Research Initiation award from the IEEE/Engineering Foundation and a Silver Quill award from Motorola-Austin (1996).Dr. Lombardi was an Associate Editor (1996–2000) of IEEE Transactions on Computers and a Distinguished Visitor of the IEEE-CS (1990–1993 and 2001–2004). Since 2000, he has been the Associate Editor-In-Chief of IEEE Transactions on Computers and an Associate Editor of the IEEE Design and Test Magazine. Since 2004 he serves as the Chair of the Committee on “Nanotechnology Devices and Systems” of the Test Technology Technical Council of the IEEE.Dr. Lombardi has been involved in organizing many international symposia, conferences and workshops sponsored by professional organizations as well as guest editor of Special Issues in archival journals and magazines such as the IEEE Transactions on Computers, IEEE Transactions on Instrumentation and Measurement, the IEEE Micro Magazine and the IEEE Design & Test Magazine. He is the Founding General Chair of the IEEE Symposium on Network Computing and Applications.His research interests are testing and design of digital systems, quantum and nano computing, ATE systems, configurable/network computing, defect tolerance and CAD VLSI. He has extensively published in these areas and edited six books.Marco Ottavi is currently postdoctoral research associate at the ECE Department of Northeastern University in Boston. He received the Laurea degree in Electronic Engineering from University of Rome “La Sapienza” in 1999 and the Ph.D. in Microelectronics and Telecommunications from University of Rome “Tor Vergata” in 2004. In 2000 he was with ULISSE Consortium, Rome as designer of digital systems for space applications. In 2003 he was visiting research assistant at ECE Department of Northeastern University. His research interests include yield and reliability modeling, fault-tolerant architectures, on-line testing and design of nano scale circuits and systems.Salvatore Pontarelli is currently postdoctoral research associate at the University of Rome, Tor Vergata. He received the Laurea degree in Electronic Engineering from the University of Bologna in 1999 and the Ph.D. in Microelectronics and Telecommunications Engineering from the University of Rome Tor Vergata in 2003. His research mainly focuses on fault tolerance, on-line testing and reconfigurable digital architectures.Adelio Salsano was born in Rome on December 26, 1941 and is currently full professor of Microelectronics at the University of Rome, Tor Vergata where he teaches the courses of Microelectronics and Electronic Programmable Systems. His present research work focuses on the techniques for the design of VLSI circuits, considering both the CAD problems and the architectures for ASIC design. In particular, of relevant interest are the research activities on fault tolerant/fail safe systems for critical environments as space, automotive etc.; on low power systems considering the circuit and architectural points of view; and on fuzzy and neural systems for pattern recognition. An international patent and more than 90 papers on international journals or presented in international meetings are the results of his research activity. At present he is the President of a national consortium named U.L.I.S.S.E., between ten universities, three polytechnics and several of the biggest national industries, as STMicroelectronics, ESAOTE, FINMECCANICA. He is responsible for contracts with the ASI, Italian Space Agency, for the evaluation and use in space environment of COTS circuits and for the definition of new suitable architectures for space applications. Professor Salsano is also involved in professional activities in the field of information technology and is also consultant of many public authorities for specific problems. In particular, he is consultant of the Departments of the Research and of the Industry, of IMI and of other authorities for the evaluation of industrial public and private research projects. Professor Salsano was a member of the consulting Committee for Engineering Sciences of the CNR (National Research Council) from 1981 to 1994 and participated in the design of public research programs in the fields of Telematics, Telemedicine, Office Automation, Telecommunication and, recently, Microelectronics and Bioelectronics.     

Antennas and Propagation Measurement Techniques for UWB Radio

The progressive development of Ultra Wide Band (UWB) antennas and microelectronics allows for a wide range of future UWB radio communication applications. The paper focuses on testing and measuring various antennas and propagation aspects important in UWB radio. The ‘Delft approach’ of measuring UWB antennas using time-domain measurement techniques is explained including the diagnostics of antenna mismatch and wave scattering from the inside and the antennas environment. The approach is illustrated with measurements.The experimental time-domain set up allows instantaneous measurements up to 26GHz. After an overview of various UWB antennas some latest developments of a miniaturized antenna are reported. UWB channel measurements in ‘short-range radio’ illustrates that good insight in the propagation of short radar pulses can be obtained. Leo P. Ligthart was born in Rotterdam, the Netherlands, on September 15, 1946. He received an Engineer's degree (cum laude) and a Doctor of Technology degree from Delft University of Technology in 1969 and 1985, respectively. He is fellow of IEE and IEEE. He received Doctorates (honoris causa) at Moscow State Technical University of Civil Aviation in 1999 and Tomsk State University of Control Systems and Radioelectronics in 2001. He is academician of the Russian Academy of Transport. Since 1992, he has held the chair of Microwave Transmission, Radar and Remote Sensing in the Department of Electrical Engineering, Mathematics and Computer Science, Delft University of Technology. In 1994, he founded the International Research Center for Telecommunications and Radar (IRCTR) and is the director of IRCTR. Prof. Ligthart's principal areas of specialization include antennas and propagation, radar and remote sensing, but he has also been active in satellite, mobile and radio communications. He has published over 300 papers.     

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.     

Security Framework for Wireless Sensor Networks

Wireless sensor network is more prone to adversary compare to common wireless network. This is due to the nature of wireless sensor network that involves many nodes, thus making the system more vulnerable. Another reason is the nature of wireless sensor network as an ad hoc network, making it having no hierarchal structure, complicating management tasks. Deploying new technology without security in mind has often proved to be unreasonably dangerous.One of the most fundamental rights in a 'healthy' society is the right of every citizen to be left alone. Article 12 of the U.N, Universal Declaration of Human Rights, states that “No one shall be subjected to arbitrary interference with his privacy, family, home or correspondence.”, in reality, though this right is increasingly being trod upon, along with undreamed of comforts and conveniences for the population in general. The digital revolution has made it possible to gather as well as store information about human behaviour on a massive scale. We leave electronic footprints everywhere we go, footprints that are being watched, analyzed and sold without our knowledge or even control.With this Security and Privacy solutions are mandatory aspects when developing new pervasive technologies such as wireless sensor networks (WSN).This paper analyses the security issues, threats and attacks and requirements of wireless sensor networks. This paper further proposes security framework and security architecture to integrate existing technologies with WSN technology, to provide secure and private communications to its users. Neeli Rashmi Prasad, Associate Professor and Head of Wireless Security and Sensor Networks Lab., part of Wireless Network including Embedded systems Group (WING), Center for TeleInfrastruktur (CTIF), Aalborg University, Aalborg, Denmark. She received her Ph.D. from University of Rome “Tor Vergata”, Rome, Italy, in the field of “adaptive security for wireless heterogeneous networks” in 2004 and M.Sc. (Ir.) degree in Electrical Engineering from Delft University of Technology, The Netherlands, in the field of “Indoor Wireless Communications using Slotted ISMA Protocols” in 1997. She joined Libertel (now Vodafone NL), Maastricht, The Netherlands as a Radio Engineer in 1997. From November 1998 till May 2001, she worked as Systems Architect for Wireless LANs in Wireless Communications and Networking Division of Lucent Technologies (now Agere Systems), Nieuwegein, The Netherlands. From June 2001 to July 2003, she was with T-Mobile Netherlands, The Hague, The Netherlands as Senior Architect for Core Network Group. Subsequently, from July 2003 to April 2004, she was Senior Research Manager at PCOM:I³, Aalborg, Denmark.During her industrial career she coordinated several projects. Just to name few major ones: country wide GSM landmass coverage (Vodafone NL), the impact of IP based security on Lucent WLAN (Wavelan later known as Orinoco) Access Points (APs), implementation of Virtual LAN and IAPP on Orinoco APs, VoIP implementation on APs, design and implementation of real-time embedded software platform for APs, mobile core network evolution towards All-IP for T-Mobile International to technical project lead for Public WLAN deployment for T-Mobile NL.Her publications range from top journals, international conferences and chapters in books. She has also co-edited and co-authored two books titled “WLAN Systems and Wireless IP for Next Generation Communications” and “Wireless LANs and Wireless IP Security, Mobility, QoS and Mobile Network Integration”, published by Artech House, 2001 and 2005. She has supervised several Masters Students projects.In December 1997 she won Best Paper award for her work on ISMA Protocol (Inhibit Sense Multiple Access). Her current research interest lies in wireless security, mobility, mesh networks, WSN, WPAN and heterogeneous networks.She was the Technical Program Committee Co-Chair IWS2005/WPMC05 held on September 18–22, 2005 in Aalborg. She is the Project Coordinator of EC Network of Excellence Project CRUISE on Wireless Sensor Networks. She is also cluster leader of EC Cluster for Sensor Networks. Mahbubul Alam, Ph.D. student at Center for TeleInfrastruktur (CTIF), Aalborg University, Denmark. He is with Cisco Systems, Inc. Netherlands from 2001 and worked as Consulting Systems Engineer in the field of mobile and wireless technology and since September 2002 he works as Business Analyst in areas of mobile, wireless and security. He is now based in Cisco Systems, Inc. San Jose, CA, USA, with focus on home networking, wireless and security. Previously he was with Siemens Netherlands as Systems Engineer and as Technical Team Leader of UMTS group. He received M. Sc. degree in Electrical & Electronic Engineering from Delft University of Technology, The Netherlands in 1998. He has published several papers at international conferences, journals, IEEE communication magazine and chapters for books. His research interest is in the field of wireless sensor networks.