Development of Behavioural Models for Mechanically Loaded Microcantilevers and Beams

From a modelling viewpoint MEMS are very complex structures. The development of full mathematical models is an extremely challenging problem. Some of the methods, assumptions and simplifications commonly used when modelling macroengineering structures may not be applied to real MEMS. Furthermore applying well-known behavioural models developed for macrostructures to microdevices has proved to be questionable if not inappropriate. Thus alternative approaches need to be used and new models need to be developed. This paper presents mathematical models of mechanical behaviour of micromachined cantilevers and beams on supports under uniform or concentrated load. The models were extracted from finite element simulation data using dimensional analysis.Maryna Lishchynska received a M.Sc. in Applied mathematics from Lviv Polytechnic State University, Ukraine in 1993, and was awarded Ph.D. in Technical Sciences from the Institute of Physics and Mechanics of the National Academy of Sciences of Ukraine in 2000. Dr. Lishchynska’s Ph.D. research was in the area of deformable solid mechanics (fatigue fracture mechanics). During 1993–2001 she worked as a research scientist on fracture mechanics problems for the Institute of Physics and Mechanics of the National Academy of Sciences of Ukraine and published a range of papers. Maryna joined the Tyndall National Institute (Cork, Ireland) in 2003 as a post-doctoral researcher in the Computational Modelling Group. She is currently involved in development of behavioural models of microsystems structures.Nicolas Cordero received Ing. Superior de Telecomunicación at Polytechnical University of Madrid. He is at Tyndal National Institute (Cork, Ireland) since 1990. Here he has worked on numerical modelling of electronic and optoelectronic devices based on compound semiconductors (MESFETs, HEMTs, Schottky diodes, Lasers and LEDs). He has also worked on modelling of photo-voltaic (PV) systems. Since 2001 Nicolas is at the Computational Modelling Group working on thermal and thermo-mechanical modelling, including finite element modelling of MEMS.Orla Slattery obtained a B.E. in civil engineering from University College Cork in 1989, M.Eng.Sc (civil engineering) in 1991 and M.Eng.Sc (electronics) 1998. In 1991 she joined the Interconnection and Packaging Group at NMRC where she was responsible for simulation and characterisation of thermal and thermomechanical issues in electronics components and systems. Since 1999 she has been working as a research scientist with the Computational Modelling Group in NMRC. She has participated in a number of European Union and Irish Government funded projects as well as providing services to Irish and European Industry. Her current research interests include the application of computational simulation tools to the solution of thermal and thermomechanical problems in microelectronics components and systems. She has published a range of papers in these areas. She is also involved in modelling and simulation of MEMS and is currently vice-chair of the EU funded Network of Excellence on Design for Micro and Nano manufacture, PATENT- DfMM.     

(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.     

Subcarrier and Power Allocation for the Downlink of Multiuser OFDM Transmission

In this paper, a new algorithm for subcarrier and power allocation for the downlink of multiuser OFDM transmission is presented. The proposed algorithm is more stable and it offers a lower complexity and better performance than previous existing algorithms. Khalid El Baamrani was born in Ouarzazate, Morocco in 1976. He received the License degree (equiv. B.A.) in electronic engineering from the University of Cadi Ayyad, Marrakech, Morocco, in 1998, the D.E.S.A. (equiv. M.A) in electrical engineering from the University of CadiAyyad, Marrakech, Morocco, in 2000, the certificate in engineering of the data-processing networks and telecommunications from the national institute of posts and telecommunications, Rabat, Morocco in 2002 and the Ph.D. degree at University of Cadi Ayyad, Marrakech, Morocco in 2005. His research interests include multicarrier modulation, communication theory, multiuser information theory, OFDM and DSL systems. Victor P. Gil Jiménez received the B. Eng. in Telecommunications with honors from University of Alcalá in 1998 and the M. Eng. in Telecommunications and the PhD. degree both from the University Carlos III de Madrid in 2001 and 2005, respectively. He is with the Department of Signal Theory and Communications at the University Carlos III de Madrid as an Assistant Professor. He worked at the Spanish Antarctica Base in 1999 as Communications Staff. He visited University of Leeds and Chalmers Technical University in 2003 and 2004 respectively. His research interests include multicarrier communications and signal processing for wireless systems. Ana Garcia Armada received the Telecommunication Engineer degree and the Ph.D in Electrical Engineering both from the Polytechnic University of Madrid (Spain) in 1994 and 1998, respectively. She is currently working as an Associate Professor at the University Carlos III de Madrid, where she has occupied several management positions. She has participated in several national and international research projects, most of them related to OFDM. She is coauthor of four books on wireless communications and signal processing. She has published 13 papers in international journals and more than 40 papers in conferences. She has contributed to international organizations such as ITU and ETSI. She has performed research stays in ESA-ESTEC, Kansas University, Stanford University and Bell Labs. Her research interests are simulation of communication systems, multicarrier and MIMO techniques.     

Metadata Design for Reconfigurable Protocol Stacks in Systems Beyond 3G

Global consensus on the next generation of wireless mobile communications, broadly termed “beyond 3G”, sketches a heterogeneous infrastructure comprising different wireless systems in a complementary manner and vested with reconfiguration capabilities, which support a flexible and dynamic adaptation of the wireless network and its spectrum resources to meet the ever-changing service requirements. For ubiquitous reconfiguration to become a practical capability of mobile communication systems, it is necessary to establish a global architecture for modeling, expressing, and circulating essential metadata related to reconfiguration, including reconfigurable device capabilities and semantic properties of protocol stacks. We outline the relevant standardization initiatives in the mobile domain, summarize existing work in reconfiguration-supporting architectures, and identify key shortcomings that may hinder the advent of ubiquitously reconfigurable systems. Further on, we point out some major limitations of current metadata standards in the mobile domain for the representation of capability information pertaining to reconfigurable protocol stacks. Next, we identify essential metadata classes in support of reconfigurable communication systems, introducing an associated object-oriented UML model. We elaborate on the design rationale of the UML model, presenting and discussing the alternative metadata representation standards and suitable encoding formats. Finally, we demonstrate the suitability of our UML model by applying our reconfiguration-supporting vocabulary in the cases of a standardized protocol stack of 3G mobile devices and stationary 3G cellular network elements. Vangelis Gazis received his B.Sc. and M.Sc. (Communication Networking) degrees from the Department of Informatics & Telecommunications of the University of Athens, Greece, in 1995, and 1998, respectively. He also received an M.B.A. degree from the Athens University of Economics and Business in 2001. Since 1996 until, he has been with the research staff of the Communication Networks Laboratory (CNL) of the University of Athens. He has participated in national and European research projects (MOBIVAS, ANWIRE) of the IST framework programme. He specializes in reconfigurable mobile systems and networks for beyond 3G, metadata and ontology languages, reflective and component middleware, adaptable services and open API frameworks for telecommunications. He is currently a Ph.D. candidate in the Department of Informatics & Telecommunications of the University of Athens. Nancy Alonistioti holds a B.Sc. degree and a Ph.D. degree in informatics and telecommunications from the University of Athens. Presently, she is a senior researcher in the Department of Informatics and Telecommunications of the University of Athens. In the past, she has held a research position with the Institute of Informatics and Telecommunications of NCSR “Demokritos” in the areas of protocol and service design and testing, mobile systems (UMTS), open architectures, and software defined radio systems and networks. Her current research interests are in reconfigurable mobile systems and networks beyond 3G, and adaptable services, pervasive computing and context awareness. She has participated in several national and European R&D projects, and has been the technical manager of the IST-MOBIVAS and IST-ANWIRE projects, which have had a focus on reconfigurable mobile systems, networks an respective service provision. She is currently a member of the management team and workpackage leader in the FP6 IST-E2R project on reconfigurability; she also serves as technical manager for the University of Athens in the FP6 IST-LIAISON project, which focuses on location based services in working environments. Dr Alonistioti is co-editor and co-author of the book entitled “Software defined radio, Architectures, Systems and Functions”, published by John Wiley in May 2003. She has authored over 55 publications in the area of mobile communications and reconfigurable systems and networks. Lazaros Merakos received the Diploma in electrical and mechanical engineering from the National Technical University of Athens, Athens, Greece, in 1978, and the M.S. and Ph.D. degrees in electrical engineering from the State University of New York, Buffalo, in 1981 and 1984, respectively. From 1983 to 1986, he was on the faculty of the Electrical Engineering and Computer Science Department, University of Connecticut, Storrs. From 1986 to 1994, he was on the faculty of the Electrical and Computer Engineering Department, Northeastern University, Boston, MA. During the period 1993D1994, he served as Director of the Communications and Digital Processing Research Center, Northeastern University. During the summers of 1990 and 1991, he was a Visiting Scientist at the IBM T. J. Watson Research Center, Yorktown Heights, NY. In 1994, he joined the faculty of the University of Athens, Athens, Greece, where he is presently a Professor in the Department of Informatics and Telecommunications, and Director of the Communication Networks Laboratory (UoA-CNL) and the Networks Operations and Management Center. Since 1995, he is leading the research activities of UoA-CNL in the area of mobile communications, in the framework of the Advanced Communication Technologies and Services (ACTS) and Information Society Technologies (IST) programs funded by the European Union (projects RAINBOW, Magic WAND, WINE, MOBIVAS, POLOS, ANWIRE, E2R, LIAISON). His research interests are in the design and performance analysis of communication networks, and wireless/mobile communication systems and services. He has authored more than 190 papers in the above areas. Dr. Merakos is Chairman of the Board of the Greek Universities Network, the Greek Schools Network, and Member of the Board of the Greek Research Network. In 1994, he received the Guanella Award for the Best Paper presented at the International Zurich Seminar on Mobile Communications.     

QoS Mechanisms for the MAC Protocol of IEEE 802.11 WLANs

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

Low Power Downlink MAC Protocols for Infrastructure Wireless Sensor Networks

This paper addresses low power medium access control (MAC) protocols for the downlink channel of infrastructure wireless sensor networks. Access points are assumed to be energy unconstrained. The trade-off between the power consumption of the sensor nodes and the transmission delay is analyzed, focusing on low traffic. We describe WiseMAC (Wireless Sensor MAC), a new protocol for the downlink of infrastructure wireless sensor networks. Another original contribution is the presentation and analysis of PTIP (Periodic Terminal Initiated Polling). Here, polling is used in the reversed direction as compared to common polling protocols. WiseMAC and PTIP are compared with PSM (Power Save Mode), the power save protocol used in both the IEEE 802.11 and IEEE 802.15.4 ZigBee standards. Analytical expressions are derived for the power consumption and the transmission delay for each protocol, as a function of the wake-up period. It is shown that WiseMAC provides, with low bit rate radio transceivers, a significantly lower power consumption than PSM. Although less energy efficient than WiseMAC and PSM, it is shown that PTIP can, thanks to its implementation simplicity, become attractive for applications tolerating large transmission delays.Amre El-Hoiydi received the electrical engineer degree from the Swiss Federal Institute of Technology in Zurich (ETHZ), Switzerland, in 1994. In 1995, he was a teaching assistant at the Swiss Federal Institute of Technology in Lausanne (EPFL), working on mobility management for low earth orbit mobile satellite communication systems. In 1996, he joined CSEM (Neuchâtel, Switzerland). Since then, he has been working on several research and development projects dealing with various aspects of wireless communications. In the ACTS RAINBOW and FRAMES projects, he was involved with the network and air interface aspects of 3rd generation cellular systems. In the ESPRIT INFOGATE and IST OPENROUTER projects, he worked on electronic design and embedded programming of Linux based wireless LAN gateways. His current research focus is low power communication protocols for wireless sensor networks.Jean-Dominique Decotignie is head of the real-time and networking group at the Swiss Center for Electronics and Microsystems (CSEM) in Neuchâtel. He is professor at the School of Computer and Communication Sciences of EPFL (Swiss Federal Institute of Technology in Lausanne) and teaches real-time systems as well as hardware and software design. From 1977 to 1982, he has worked at EPFL and the University of Tokyo in the area of optical communications. In 1983, he joined the Industrial Computer Engineering Lab. at EPFL where he became Assistant Professor in 1992. From 1989 to 1992, he has been the head of an interdisciplinary project on Computer Integrated Manufacturing at EPFL. Since January 1997, he is with CSEM. His current research interests include industrial and real-time local area networks, distributed control systems and software engineering for real-time systems as well as real-time wireless networks.     

Specification and Dynamic Introduction of 3rd Party,Service-Specific Adaptation Policies for Mobile Applications

The development, delivery and management of mobile services are the subject of many research activities in both the academia and industry. The ultimate goal of these efforts is a dynamic environment that enables the delivery of situation-aware, personalised multimedia services over heterogeneous, ubiquitous infrastructures, commonly termed as systems beyond 3rd generation (3G). Reconfigurability and adaptability are key aspects of the mobile systems beyond 3G. Reconfigurable mobile systems and networks introduce additional requirements and complexity in service adaptation. Moreover, it is widely recognised that services will be increasingly developed by independent third parties, besides mobile operators and equipment vendors. The present contribution complements previous work by the authors, related to mediating service provision platforms and advanced adaptability and profile management frameworks. It introduces mechanisms and middleware that undertake the service adaptation overhead, imposed by the complexity of reconfigurable mobile networks, from application developers and third party service providers. In particular, it enables the introduction of third party policies for adaptation decision. Finally, it facilitates the adaptable application development and service deployment independently from the underlying dynamically reconfigurable communication environment. Nikos Houssos holds a B.Sc. and a Ph.D. degree from the Department of Informatics Telecommunications at the University of Athens, Greece, and an M.Sc. degree (with distinction) in Telematics from the department of Electronic and Electrical Engineering, University of Surrey, UK. Since 1999, he is working at the Communication Networks Laboratory of the University of Athens. He has participated in various research projects of the European Union IST framework (MOBIVAS, ANWIRE, POLOS, E2R). His research interests include middleware platforms and business models for mobile service provision in 3G/4G environments, service adaptability, network reconfigurability and context-aware pervasive systems. Nancy Alonistioti has a B.Sc. degree and a PhD degree in Informatics and Telecommunications (University of Athens). She has been working for several years at the Dept. of Informatics and Telecommunications in University of Athens as a senior researcher and project manager. She has been involved in many European and national projects (CTS, SS#7, ACTS RAINBOW, EURESCOM) in the areas of protocol and service design of mobile systems. She has been the Technical manager of the IST-MOBIVAS and IST-ANWIRE projects. She had been working as expert at the Greek Regulatory Agency. She is member of the core management team of the Greek Universities Network (GUNET). Her current research includes: mobile communications, re-configurable mobile systems and networks, adaptability, service provision, protocol design and mobile computing. Lazaros Merakos received a Diploma in electrical and mechanical engineering form the National Technical University of Athens, Greece, in 1978 and M.S. and Ph.D. degrees in electrical engineering from the State University of New York, Buffalo, in 1981 and 1984, respectively. From 1983 to 1986 he was on the faculty of Electrical Engineering and Computer Science at the University of Connectitut, Storrs. From 1986 to 1994 he was on the faculty of the Electrical and Computer Engineering Department at Northeastern University, Boston, Massachusetts. During the period 1993–1994 he served as a director of the Communications and Digital Processing Research Center at Northeastern University. During the summers of 1990 and 1991, he was a visiting scientist at the IBM T. J. Watson Research Center, Yorktown Heights, New York. In 1994 he joined the faculty of the University of Athens, Greece, where he is presently a professor in the Department of Informatics and Telecommunications, and director of the Communication Networks Laboratory (UoA-CNL) and the Networks Operations and Management Center. His research interests are in the design and performance analysis of broadband networks, and wireless/mobile communication systems and services. He has authored more than 150 papers in the above areas. Since 1995, he is leading the research activities of UoA-CNL in the area of mobile communications, in the framework of the Advanced Communication Technologies and Services (ACTS) and Information Society Technologies (IST) programs funded by the European Union (projects RAINBOW, Magic WAND, WINE, MOBIVAS, POLOS). He is chairman of board of the Greek Universities Network, the Greek Schools Network, and a member of the board of the Greek Research Network. In 1994 he received the Guanella Award for the Best Paper presented at the International Zurich Seminar on Mobile Communications.This revised version was published online in August 2005 with a corrected cover date.     

A 1.3-Gsample/s interpolation with flash CMOS ADC based on active interpolation technique

In this paper, the design of a high-speed low-voltage CMOS interpolation with flash analog-to-digital converter (ADC) in CMOS 0.18-μm process is presented. The use of summing differential amplifiers operating in continuous time for interpolation and resistor averaging circuit have significantly improved the circuit’s linearity. The new interpolation technique has improved the pertinent phase delay problem of voltage interpolation enormously. A technique to reduce metastability errors in the Error Correction Circuitry is also presented. The circuit achieves a maximum sampling speed of 1.3 GHz. The measured signal-to-noise-plus-distortion ration (SNDR) is 32 dB at 500 MHz. Peak DNL and INL are less than 0.15 LSB and 0.35 LSB, respectively. This ADC consumes about 600 mW from 1.8 V at full speed. The chip occupies 0.56-mm² active area, prototyped in CMOS 0.18-μm technology. Shazia Seemi was born in New Delhi, India in 1976. She received Bachelor of Technology in Electronics and Communication from JMI University, New Delhi, India in 1998. From 1998 to 2000, she was working with NIIT as an Associate Engineer. She worked as a Software Engineer with Samsung Electronics in 2001. Currently she is a postgraduate student at the VLSI Research Group, Multimedia University, Malaysia, doing research in the area of CMOS high speed ADC design. Mohd Shahiman Sulaiman received the 1st. Class Honors, Co-op B.A.Sc. degree in Electrical Engineering and the M.A.Sc. degree in Electrical & Computer Engineering from the University of Waterloo, Ontario, Canada. He has worked in the area of low-power high-speed mixed-signal IC design since 1998. In 1998, he worked with the VLSI Research Group, University of Waterloo, Canada designing low-power PLL-based frequency synthesizer for Actel Corporation. In 1999, he worked with Actel Corporation in Sunnyvale, CA, USA designing an optimized clock network for Actel,s SX and SX-A anti-fused. Mohd S Sulaiman is currently a lecturer at the Faculty of Engineering, Multimedia University, Malaysia. He is a research associate for Intel Corporation (Malaysia) and Matsushita Electric Industrial Co., Ltd., Japan, as well as consultant for Multimedia Development Corp., Agilent Technologies, Telekom R&D, and PSDC, Malaysia as well as ActiveMedia Innovation Pte Ltd, Singapore. His current research work includes low-power high-performance integrated circuit design, low-power high-speed frequency synthesis techniques, signal integrity, and VLSI system design. He has authored/co-authored more than 30 international conference/journal papers on integrated circuit design and design automation. Arshad Suhail Farooqui was born in Aligarh, India in 1977. He received his Bachelor of Technology in Electronics and Communication from JMI University, New Delhi, India in 1998. From 1998 to 2000, he was working as an Embedded Software Engineer with Indusoft, Delhi, India. From 2000 to 2001, he was with Samsung Electronics, Bangalore, India, as a Senior Software Engineer. From 2002 to 2005, he was with Sires Labs Bhd., Cyberjaya, Malaysia as an ASIC Design Engineer. Arshad is a postgraduate student at the VLSI Research Group, Multimedia University working on high-speed clock and data recovery circuit.     

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

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

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 0.8 μm CMOS testable switched-capacitor filter for video frequency applications

This paper presents the design of a fifth-order low-pass elliptic filter that employs a parallel connection of two all-pass sections to satisfy specifications commonly used in video frequency applications. Operating with a sampling frequency of 16 MHz, the IC prototype was implemented in a standard double-poly CMOS 0.8 μm process. The experimental verification showed a passband frequency deviation smaller than 0.08 dB up to the passband edge frequency of 3.4 MHz, and an output noise power of 0.97 ${\mu {\rm V}_{\rm RMS}}/{\sqrt {Hz}}This paper presents the design of a fifth-order low-pass elliptic filter that employs a parallel connection of two all-pass sections to satisfy specifications commonly used in video frequency applications. Operating with a sampling frequency of 16 MHz, the IC prototype was implemented in a standard double-poly CMOS 0.8 μm process. The experimental verification showed a passband frequency deviation smaller than 0.08 dB up to the passband edge frequency of 3.4 MHz, and an output noise power of 0.97 , resulting in a dynamic range of 49.1 dB. The filter structure enables multiple fault detection and suits modern automated testing configurations to allow accurate estimation of the actually implemented transfer function parameters, an issue of increasing importance in VLSI circuit design. The relative area required for testing the fifth-order filter is only 8% of the total filter area, and decreases as the filter order increases. Jorge Morales Ca?ive was born in Cienfuegos, Cuba, in 1963. He received the B.Sc. and M.Sc. degrees from the Technical University of San Petersburg, Russia, in 1986 and 1988, respectively, and the D.Sc. degree from the Federal University of Rio de Janeiro, Brazil, in 1991, all in electrical engineering. From 1988 to 1994, he worked at CEADEN, in Havana, Cuba, on the development of nuclear equipments. From 1994 to 1997, he worked at INOR, in Havana, Cuba, on the research and development of acquisition systems and image processing for nuclear medicine. His research interests are in the areas of analog and digital signal processing. Antonio Petraglia (S’89-M’91-SM’99) received the Engineer and M.Sc. degrees from the Federal University of Rio de Janeiro (UFRJ), Brazil, in 1977 and 1982, respectively, and the Ph.D. degree from the University of California, Santa Barbara (UCSB), in 1991, all in electrical engineering. In 1979, he joined the Faculty of UFRJ as an Associate Professor of electrical engineering, where he served as a Co-Chair in the Department of Electronic Engineering from 1982 to 1984. During the second semester of 1991, he was a post-Doctoral researcher with the Department of Electrical and Computer Engineering at UCSB. Since 1992 he has been on the faculty of the Program for Post-Graduate Engineering at UFRJ, where in 1997 he established the Laboratory for the Processing of Analog and Digital Signals. From March 2001 through March 2002 he was a Visiting Scholar with the Electrical Engineering Department at the University of California, Los Angeles. He has been involved in teaching and research activities in the areas of analog and digital signal processing, and in mixed analog-digital integrated circuit design. He is a distinguished member of the Brazilian Millenium Group in Nanoelectronics and Microelectronics in 2006-2008. Dr. Petraglia served as an Associate Editor for the IEEE Transactions on Circuits and Systems-II: Analog and Digital Signal Processing in 2002–2003 Mariane Rembold Petraglia (M’97) received the B.Sc. degree in electronic engineering from the Federal University of Rio de Janeiro, Brazil, in 1985, and the M.Sc. and Ph.D. degrees in electrical engineering from the University of California, Santa Barbara, in 1988 and 1991, respectively. From 1992 to 1993, she was with the Department of Electrical Engineering, Catholic University of Rio de Janeiro, Brazil. Since 1993, she has been with the Department of Electronic Engineering and with the Program of Electrical Engineering, COPPE, at the Federal University of Rio de Janeiro, where she is presently an Associate Professor. From March 2001 to February 2002, she was a Visiting Researcher with the Adaptive Systems Laboratory, at the University of California, Los Angeles. Her research interests are in adaptive signal processing, multirate systems, and image processing. Dr. Petraglia is a member of Tau Beta Pi, and a distinguished member of the Brazilian Millenium Group in Nanoelectronics and Microelectronics in 2006–2008. She is serving as an Associate Editor for the IEEE Transactions on Signal Processing since Nov. 2004.     

A Stereo Multi-Rate Audio Front-End Suitable for Mobile Multimedia Applications

A flexible, high quality audio front-end integrated circuit with low power consumption is presented. Targeted for the world-wide (GSM) mobile communication system, it is capable of stereo and mono reception and transmission, supports narrow voice-band as well as wide voice-band modes, FM radio and MP3 stereo play-back. The front-end provides a low-noise bias voltage for microphones as well as hands-free buffers driving 8Ω loads in bridge tied load configuration and two earphone outputs for stereo. The front-end is highly area-efficient, occupying 1.92 mm² in a 0.25-μ m CMOS technology. Measured results show a maximum power consumption of 11.8 mW at 2.65 V analog and 1.65 V digital supply.Barbara Baggini received the Laurea degree (summa cum laude) in electronic engineering from the University of Pavia, Pavia, Italy, in 1987. She joined the Microelectronics Laboratory at the University of Pavia and worked in the field of switched capacitor filters and high-speed data converters sponsored by STMicroelectronics. From 1988 to 1996 she joined Italtel where she was involved in the development of mixed signal front-end ICs for mobile communications.She is currently with Philips Semiconductors, Switzerland. Her main research interests are in the area of analysis and design of analog and digital low-power circuits for mobile communications.Willem H. Groeneweg received a M.Sc. degree in electrical engineering from Delft University of Technology, Delft, The Netherlands, in 1971.After his military service, he joined the RCA Corporation in Zurich, Switzerland, where he developed bipolar integrated circuits and systems for video processing. In 1984 he started working in the Landis {&} Gyr Central Laboratory on CMOS integrated circuits for building automation. From 1989 on he developed bipolar mixed-signal circuits using ASIC’s from Plessey Semiconductors. Since 1993 he is with the Cellular Systems group of Philips Semiconductors in Zurich. One of his tasks there is the development of CMOS integrated circuits for mobile telephones, mainly in the field of analog and mixed signal audio circuits. Mr. Groeneweg holds 13 patents and has two applications pendingClaudio Schaitwas born on October 16, 1972, in Sorengo, Switzerland. He received the Dipl. Ing. degree in electrical engineering from the Swiss Federal Institute of Technology (ETH), Zurich, in 1999.From June 1999 to October 2000 he worked as Radio Access System engineer for Nokia, Switzerland. In November 2000 he joined Philips Semiconductor, Zurich, Switzerland as Development Engineer. His research interests are in design of CMOS Analog Baseband and Audio Signal Processing for telecom applications.     

Integrated Circuit Implementation of a Compact Discrete-Time Chaos Generator

A discrete-time chaos generator implemented with two nonlinear circuit cells has been fabricated in a 0.6 μm CMOS technology. Each cell is creating a function (map) which allows a chaos signal to be generated. Measurements of the chip were performed with a supply voltage of 5 V, up to a frequency of 2.5 MHz. A bifurcation diagram of the circuit and the Lyapunov exponent calculation are presented. The size of the generator layout (without the switches) is 32 × 19 μ m which makes it suitable for applications where many chaos signal generators are required on a single chip. Dan Juncu received the B.S. and M.Sc. degrees in Electrical and Electronics Engineering from the Technical University, Iasi, Romania in 1997 and 1998, respectively, and the Ph.D. degree in Electronics from UMIST, Manchester, UK in 2003. For his Ph.D. he did research on sensor interfaces for gas sensing devices; after that, he worked on RF IC on a new SiGe technology. In 2004 he joined Cambridge Consultants, Cambridge, UK. His current interests are in the area of switched capacitor filtering and computation, and sensor interfacing. Mandana Rafiei-Naeini received the B.Sc. degree in Electrical Engineering (majoring in Electronics) from Islamic Azad University of Tehran, Iran, in 2001 and the M.Sc. degree with distinction in Electronic Instrumentation Systems from University of Manchester in 2004. She is currently studying towards her Ph.D. degree in the School of Electrical and Electronic Engineering at The University of Manchester, working on clinical electrical impedance tomography systems for brain function imaging. She is a student member of IEE and IEEE. Piotr Dudek received his mgr in ż degree in electronic engineering from the Technical University of Gdańsk, Poland in 1997 and the M.Sc. and Ph.D. degrees from the University of Manchester Institute of Science and Technology (UMIST), Manchester, UK, in 1996 and 2000, respectively. He worked as a Research Associate at UMIST until 2002. Currently, he is a Lecturer in Integrated Circuit Engineering at The University of Manchester. His research interests are in analogue and mixed-mode VLSI circuits, smart sensors, machine vision, massively parallel processors, cellular arrays, bio-inspired engineering and spiking neural networks.     

Systematic Synthesis of Active-RC Circuit Building-Blocks

In this paper, we show how some basic building blocks for active-RC circuit design, such as amplifiers, impedance converters and simulated inductance circuits, may be synthesised in a systematic way by expansion of their port admittance matrices. The circuit topology emerges from the synthesis procedure, allowing all possible implementations to be identified and explored. Nullors representing ideal op-amps and transistors are represented within the nodal admittance matrix of a synthesised circuit by linked infinity parameters. In nodal admittance matrices describing ideal circuits synthesised, the replacement of linked infinity parameters by finite parameters provides a seamless transition to non-ideal analysis and practical circuit design.Now with the Singaporean Armed Services.David Haigh was born in Middlesex, England, in 1946. He obtained the B.Sc. degree in Electrical Engineering from Bristol University in 1968 and in 1976 he received the Ph.D. degree from the University of London. From 1968 until 1972 he worked under Dr. Wolja Saraga first at the GEC Hirst Research Centre and then, from 1972, at Imperial College London where he worked on microelectronic high precision filters. In 1987 he joined the staff of the Electronic and Electrical Engineering Department of University College London, where he studied analogue integrated circuit design with particularly interest in high frequency circuits. In 2003 he re-joined the Department of Electrical and Electronic Engineering at Imperial College London, where his interests broadened to include general approaches for analogue circuit synthesis. He is editor-in-chief (Europe) of the Analog Integrated Circuits and Signal Processing Journal.Fang Qun Tan graduated with a B.Eng. degree from Imperial College London in 2002. He then studied for the M.Sc. in Analogue and Digital integrated Circuit Design at Imperial College and graduated with distinction in 2003. His M.Sc. project was on the subject of systematic synthesis methods for analogue circuits. At present Fang Qun is with the Singapore Armed Services.Christos Papavassiliou was born in Athens, Greece, in 1960. He received the B.Sc. degree in physics from the Massachusetts Institute of Technology and the Ph.D. degree in Applied Physics from Yale University. He has worked on monolithic microwave integrated circuit (MMIC) design and measurements at FORTH in Crete, Greece, and has been involved in several European and regional projects on GaAs MMIC technology. In 1996 he joined Imperial College London, where he is currently a Senior Lecturer. He currently works on SiGe technology development as well as instrumentation and substrate noise coupling in mixed mode integrated circuit design. He has 30 publications.     

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.     

Design and frequency/phase-noise analysis of a 10-GHz CMOS ring oscillator with coarse and fine frequency tuning

A 10-GHz CMOS ring oscillator that employs a multi-pass technique for boosting its frequency is proposed in this paper. The proposed circuit allows the tuning gain to be lowered by deploying the coarse/fine frequency tuning whilst maintaining wide frequency coverage. The small signal model of the proposed delay stage and the circuit operation are discussed in this paper. The time-variant analysis presented permits accurate prediction of the frequency tuning characteristic and the results have been verified by simulation. The phase noise analysis is also discussed in detail to provide better insight to the noise that is contributed by each transistor. The calculated results agreed well with that of the simulations. Hai Qi Liu was born in Jiangsu, China, in 1979. He received the B.S. and M.Sc. degrees, both in electrical engineering from the Tianjin University, Tianjin, China, in 2000, and Tongji University, Shanghai, China, in 2003, respectively. He is currently working toward the Ph.D. degree at the Nanyang Technological University, Singapore. His research focuses mainly on the design of fully integrated oscillators and Phase-Locked Loops for optical communication applications. His research interests also include RF frequency synthesizers and RF front-end designs for wireless applications. Wang Ling Goh obtained both her B.Eng and Ph.D. degrees from the department of Electrical and Electronic Engineering at the Queen’s University of Belfast (QUB) in United Kingdom. When working on her Ph.D., she was also engaged as a research associate at the Northern Ireland Semiconductor Research Centre (NISRC) at QUB. Dr Goh joined the School of Electrical and Electronic Engineering at the Nanyang Technological University (NTU) in Singapore as a lecturer in January 1996. She is now an Associate Professor in the Division of Circuits and Systems, School of Electrical & Electronic Engineering. Dr Goh has to-date co-authored 1 book, filed 13 patents (granted), and published about 60 research papers in international conferences and journals. Her research interests are in areas of silicon device processing technologies as well as digital and mixed-signal IC designs. Liter Siek received the B.A.Sc. degree from University of Ottawa, Ontario, Canada; the M.Eng.Sc. from University of New South Wales, Sydney, Australia; and the Ph.D. from Nanyang Technological University, Singapore. From 1981 to 1983 he was employed in several companies in the area of automation and control. From 1983 to 1985, he was with SGS, currently known as ST Microelectronics situated in Castelletto, Milan, Italy, where he worked in the central R&D Laboratories for Linear IC. From 1985 to 1987, he was with the same company situated in Singapore’s Asia Pacific Design Center. Since October 1988, he has been with Nanyang Technological University. His research interests are in the design of bipolar, CMOS and BiCMOS analog/mixed signal ICs. In addition, he has authored and co-authored 53 international journal/conference technical papers.     

A Performance Comparison of Different FEC System Architectures for ATM over Wireless Multi-Carrier Modulation

In multi-carrier modulation (MCM) systems multiple relatively narrowband sub-carriers are used to alleviate the undesirable influence of frequency selective fading. This paper analyses the performance of MCM data links when forward error correction is employed either in each sub-carrier or in the main stream of bits. The influences on system performance of interleaving and suppression of the poorest sub-carriers are also analysed. José Marcos C. Brito received his diploma in electrical engineering from the National Institute of Telecommunications (Inatel), Brazil, in 1986, his M.Sc. degree in electrical engineering from State University of Campinas, Brazil, in 1998, and his Ph.D. degree in electrical engineering from State University of Campinas in 2003. Since 1986 he has been a professor at Inatel, where he has held several management positions, including vice-principal and director for research. Currently he is a Full Professor at Inatel. He has worked as a consultant for several telecommunications companies in Brazil and has published several papers in international conferences in the telecommunications area. He is the editor-in-chief of the Telecommunications Journal edited by Inatel and has served as a program committee member in some international conferences. His current research interests include computer communications networks, multiple access systems, modeling and performance evaluation of communication systems, wireless networks and error control schemes. Ivanil S. Bonatti was born in Mogi-Mirim, SP, Brazil, in 1951. He received the B.Sc. (1973) and M.Sc. (1975) degrees in Electrical Engineering from the University of Campinas, UNICAMP, Brazil, and the “Doctorat en Automatique” degree from the University Paul Sabatier, Toulouse, France, in 1981. He joined the School of Electical and computer Engineering of the University of Campinas in 1975, where he is currently a professor. His main interests are circuit theory, simulation analysis and telecommunication.     

A Radio Resource Allocation Scheme for Fixed Broadband Wireless Access Systems with Avoidance of Major Interferers

An improved radio resource allocation scheme with avoidance of major interferers is proposed and analyzed for the downlink of Fixed Broadband Wireless Access (FBWA) systems with full frequency reuse. The scheme is based on Enhanced Staggered Resource Allocation (ESRA) and permits the enhancement of the throughput per sector. Simulation results show a maximum downlink throughput per sector in excess of 44% and an increase of 10% with respect to ESRA is achieved, with Base Station (BS) selection procedure, while meeting a 15 dB signal-to-interference ratio (SIR). Nicholas Vaiopoulos was bornin Lamia in 1977. He received his Physics degree and his M.Sc.degree in electronics and radio-communications from the University of Athens, Greecein 2000and 2003, respectively. Currently, he is working towards his Ph.D. degree on the resource allocation techniques with reference to wireless systems at the Department of informatics and Telecommunications at the same University. His research interests include broadband communications systems, scheduling algorithms and power control techniques for wireless systems. Alexander Vavoulaswas born in Athens in 1976. He received his B.Sc. degree in physics and the M.Sc. degree in electronics and radio-communications in 2000 and 2002 respectively,both from the University of Athens, Greece. Currently he is working toward the Ph.D. degree on the radio resource allocation techniques with the same University. His research interest is focused on broadband wireless access and interference management. He is a student nmember of the IEEE. Dimitris Varoutas holds BSc. degree in Physics, M.Sc. in electronics and radio-communi cations and Ph.D. in telecommunications systems and technoeconomics, all from the University of Athens. He is a lecturer in the Department of Informatics and Telecommunications of University of Athens and an adjunct assistant professor in the Department of Telecommunications of the newly founded University of Peloponnese. He has participating in numerous European R&D projects in the RACE I &II, ACTS, Telematics, RISI and IST framework in the areas of telecommunications and Technoeconomics. He is an adviser in several organisations including OTE and EETT (Greek NRA for telecommunications) in the fields of telecommunications, broadband and mobile services, licensing, spectrum management, pricing and legislation. His research interests are optical, microwave communications and technoeconomic evaluation of network architectures and services. He has more than 30 publications in refereed journal and conferences in the area of telecommunications, optoelectronics and technoeconomics. He is a member of IEEE and serves as reviewer in several journals and conferences. Thomas Sphicopoulos received the Physics degree from Athens University in 1976, the D.E.A. degree and Doctorate in Electronics both from the University of Paris VI in 1977 and 1980 respectively, the Doctorat Es Science from the Ecole Polytechnique Federale de Lausanne in 1986. From 1976 to 1977 he worked in Thomson CSF Central Research Laboratories on Microwave Oscillators. From 1977 to 1980 he was an Associate Researcher in Thomson CSF Aeronautics Infrastructure Division. In 1980 he joined the Electromagnetism Laboratory of the Ecole Polytechnique Federal de Lausanne where he carried out research on Applied Electromagnetism. Since 1987 he is with the Athens University engaged in research on Broadband Communications Systems. In 1990 he was elected as an Assistant Professor of Communications in the Department of Informatics & Telecommunications, in 1993 as Associate Professor and since 1998 he is a Professor in the same Department. His main scientific interests are Microwave and Optical Communication Systems and Networks and Techno-economics. He has lead about 40 National and European R&D projects. He has more than 100 publications in scientific journals and conference proceedings. From 1999 he is advisor in several organisations including EETT (Greek NRA for telecommunications) in the fields of market liberalisation, spectrum management techniques and technology convergence.     

Resource management of IP-enabled DVB-T networks in the context of wireless B3G systems

The wireless beyond 3G systems or the so called Composite Radio Environments (CRE) (or even 4G systems), consist of multiple type radio access technologies, collaborating with each other, providing both diverse access alternatives and QoS improvement, especially as far as concerns protection against traffic congestion and loss of radio coverage situations. The merits deriving from beyond 3G systems interest not only network and service providers but also the mobile users. Additionally, the need of broadband wireless access is directly associated with the intense demand for IP multimedia services (e.g. video streaming or high speed web browsing), mainly inside hot-spot areas. Taking into consideration the above described tendency in the area of wireless network systems, the IP-enabled DVB-T (the terrestrial specification of the Digital Video Broadcasting family) systems appear as an attractive alternative network access in the CRE context. Along this direction, this paper presents the most important aspects of a CRE network management system (NMS), focusing on the component responsible for the DVB-T resource management (RM). Finally, we implement and investigate through simulation a greedy algorithm suitable for DVB-T networks that performs fast resource management and configuration. We also provide some indicative results which prove that the algorithm demonstrates a close to optimal performance at the RM functionality. This work is partially funded by the Commission of the European Communities, under the Fifth Framework Program, within the IST project CREDO (Composite Radio for Enhanced Service Delivery during the Olympics). Dimitris Kouis is currently a research associate at the Electrical Engineers School of the National Technical University of Athens, in Greece. He received his diploma from the Computer Engineering and Informatics department of the Polytechnic School of the University of Patras and a Ph.D. degree in Telecommunications and Computing from the National Technical University of Athens, Greece, in 1999 and 2005 respectively. He has worked in research projects in the context of the IST framework. His research interests include mobile and wireless networking, wireless network resources optimization techniques and large-scale software platforms. He is a member of the Technical Chamber of Greece since 1999. Panagiotis Demestichas received the Diploma and the Ph.D. degrees in Electrical and Computer Engineering from the National Technical University of Athens (NTUA). From September 2002 he is an Assistant Professor at the University of Piraeus, in the department of Technology Education and Digital Systems. From 1993 until August 2002 he has been a senior research engineer with the Telecommunications Laboratory in NTUA. From February 2001 until August 2002 he was a lecturer at NTUA, in the department of Applied Mathematics and Physics, teaching courses on programming languages, data structures, data bases, telecommunications. From September 2000 until August 2002 he taught telecommunication courses, in the department of Electronics of the Technological Education Institute of Piraeus. Most of his current activities focus on the FP6/IST project E2R (End-to-End Reconfigurability). He is also the chairman of Working Group 6 (WG6), titled Reconfigurability, of the Wireless Word Research Forum (WWRF). At the international level he has actively participated in the projects IST MONASIDRE Management of Networks and Services in a Diversified Radio Environment), where he was the project manager, as well as other EU projects under the IST, ACTS, RACE II, EURET, BRITE/EURAM frameworks. His research interests include the design, management and performance evaluation of mobile and broadband networks, service and software engineering, algorithms and complexity theory, and queueing theory. He has authored over 100 publications in these areas in international journals and refereed conferences. He is a member of the IEEE, ACM and the Technical Chamber of Greece. George Koundourakis was born in Alex/polis, Greece, in 1979. He received the degree of Electrical and Computer Engineer from the National Technical University of Athens (NTUA), Greece, in July 2001. He is a Research Associate and PhD candidate at the Telecommunications Laboratory of the Division of Communication, Electronic and Information Engineering at NTUA. He has worked in research projects in the context of the IST framework. He is the author of several scientific papers in the areas of mobile communications. He is a member of the Technical Chamber of Greece. Michael E. Theologou received the degree in Electrical Engineering from Patras University and his Ph.D. degree from the School of Electrical Engineering and Computer Science of the National Technical University of Athens (NTUA). Currently he is a Professor in the School of Electrical Engineering and Computer Science of NTUA. His research interests are in the field of Mobile and Personal communications. He has many publications in the above areas. Dr Theologou is a member of IEEE and the Technical Chamber of Greece.     

System Throughput Analysis of Rate Adaptive TDMA System Supporting Two Class Services

In this paper, an adaptive transmission scheme is proposed to improve the spectral efficiency of TDMA systems. Services accommodated in such systems are classified as QoS services and BE services. Unlike conventional adaptive TDMA systems where the time slot duration is fixed for each user, our proposed system employs transmission slots with adaptive duration. For QoS services, rate adaptive modulation is adopted to make use of the instantaneous channel conditions of individual user. For BE services, a media access control strategy (MAC) that takes the instantaneous transmission conditions of all physical links of all BE services into consideration is employed. A framework to study the proposed system in terms of the average packet loss and the average system throughput is presented. The maximum number of QoS services that can be supported in the system while a predefined requirement on the average packet loss is still satisfied is investigated. A comparison study shows that our proposed scheme has higher system throughput over both conventional fixed and adaptive TDMA systems. Ronghong Mo received her B.Sc. and M. Sc. Degree from Zhongshan University, Guangzhou, China, both in Physics. From July 1999 to July 2003, she was a research scholar in the department of Electrical and Computer Engineering in National University of Singapore (NUS), toward her PhD degree. She is currently working as a research engineer in NUS. Her research interests include adaptive modulation, synchronization and channel estimation in wireless communications. Yong Huat Chew received the B.Eng, M.Eng and Ph.D. degrees in Electrical Engineering from National University of Singapore, Singapore. Since 1996, he has been with the Institute for Infocomm Research (formerly also known as Center for Wireless Communications and Institute for Communications Research), an institute under Agency for Science, Technology and Research, where he is presently a lead Scientist. His research interests are in wireless communications, transmission over HFC, DSL and all-optical networks.