A Blind Modulation Type Detector for DPRS Standard

In this paper, some methods allowing automatic discrimination between the types of modulations proposed by the DPRS communication standard are presented. In a non-cooperative context, the receiver must first be able to detect the presence of a modulated signal before eventually carrying out its demodulation (i.e. having access to the information). For this purpose a receiver capable of identifying digital modulations of type M-QAM, 8-PSK and GMSK, proposed by the ETSI–DPRS standard, has been studied. Three detection algorithms have been investigated. The first is based on the observation of the amplitude histograms, the second on the continuous wavelet transform and the third on the maximum likelihood for the joint probability densities of phases and amplitudes. Their performance has been evaluated against signal to noise ratio. Iyad W. Dayoub was born in Messiaf, Syria, in 1969. He received the Dipl.-Ing. degrees in electronic engineering from the University of Tichreen-Syria, in 1993. He received the Dipl.-MS from the University of Nancy-France, in 1997. In 2001, he received the Dipl of Dr.-Ing. degrees in electronics from the University of Valenciennes-France. From 1993 to 1998, he was Engineer in Siemens-Damascus, Syria. From 2000 to 2002, he has been an Instructor and Researcher at the University of Valenciennes, France. Actually, he is assistant Professor at the University of Valenciennes. His current research interests include blind equalization, detection algorithms and radio over fibre networks. Anicet Okassa M’Foubat was born in Okondja, Gabon, in 1979. He received the Dipl.-BS. degrees in electronic engineering from the University of Mons, Belgium, in 2002. He received the Dipl.-MS from the University of Valenciennes-France, in 2004. Since 2004 he is a PHD student at the University of Valenciennes. His current research interests are in blind detection algorithms and multi-users detection for radio-optical networks. Romaric Mvone Evina was born in Minvoul, Gabon, in 1975. He received the Dipl.-BS. Degrees in Physics from the University of Amiens, France, in 2002. He received the Dipl.-MS from the University of Valenciennes-France, in 2003. Since 2003 he is a PhD student at the University of Valenciennes. His current research interests are in blind detection algorithms and equalizers for cellular standards. Jean-Michel Rouvaen was born in 1947. He received his M.S. degree in 1968 and his Ph.D. degree in 1971, from the University of Lille (France). He is now Professor in electronics at University of Valenciennes. Some ten years ago, he was involved in non-linear phenomena, ultrasonics and acousto-optics. His primary research interests are now in signal processing and telecommunication.     

Multi-User MIMO Mobile CDMA Uplink System Employing Turbo Coding and Joint Detection Through a Multipath Rayleigh Fading Channel

In this paper, a generalized multiple-input multiple-output (MIMO) antenna system that can be fitted to the uplink of a wireless communication system is considered for the general case of multi-user. At the transmitter, the information bits are Turbo coded, then interleaved and passed through a serial-to-parallel converter. The channel is assumed bad urban suffering from multipath Rayleigh fading resulting in inter-symbol and multiple access interferences (ISI and MAI). At the front-end of the receiver, a number of receiving antennas are used followed by a joint multi-user estimator based on the Minimum Mean Square Error Block Linear Equalizer (MMSE-BLE).Computer simulations demonstrate a significant performance improvement in both single user and multi-user cases.This paper depends in parts on that presented at the 11th European Wireless Conference, Cyprus, Nicosia, pp. 187–192, April 2005. Yasmine A. Fahmy was born in Guiza, Egypt, on June 4, 1976. She received the B.Sc., M.Sc. and Ph.D. degrees in Communication and Electronics engineering from Cairo University, Egypt on 1999, 2001 and 2005 respectively. She is presently an assistant professor at Cairo University, Egypt. Her current field of interest is wireless communication and channel estimation. Hebat-Allah M. Mourad received her B.Sc., M. Sc. and Ph.D. degrees in electrical communication engineering from Cairo University, Egypt, in 1983, 1987 and 1994 respectively. Since 1983, she has been with the Department of Electronics and Communications, Faculty of Engineering, Cairo University, and is currently associate professor there. Her research interests include optical fiber communications, mobile and satellite communications. Emad K. Al-Hussaini received his B.Sc degree in Electrical Communication Engineering from Ain-Shams University, Cairo, Egypt, in 1964 and his M.Sc and Ph.D. degrees from Cairo University, Giza, Egypt, in 1974 and 1977, respectively. From 1964 to 1970, he was with the General Egyptian Aeroorganization. Since 1970, he has been with the Department of Electronics and Communications, Faculty of Engineering, Cairo University, and is currently professor there. He was a research fellow at Imperial College, London, UK, and at the Moore School of Electrical Engineering, University of Pennsylvania, Philadelphia, PA, USA, in the academic years 1976/1977 and 1981/1982, respectively. In 1990, he received the Egyptian national encouragement award for outstanding engineering research. He has written several papers for technical international journals and conferences. His research interests include signal processing, fading channel communication, modulation, and cellular mobile radio systems. Dr Al-Hussaini is a senior member of IEEE. He is listed in Marquis Whos Who in the World and in the IBC (International Biographical Center, Cambridge) for outstanding people of the 20th century.     

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.     

Introducing consciousness in UWB networks by hybrid modelling of admission control

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

A Novel Switched Parasitic Array and Diversity Scheme Using Horizontally Polarized Linear Antennas

Switched Parasitic Arrays (SPAs) are proposed as an attractive alternative to fully adaptive arrays, due to their compact size and significantly lower cost of development. The main concept of SPAs is the deployment of switches on parasitic elements, which can be properly adjusted, in order to effectively control the radiation pattern of one active element. Conventional SPAs consist of circular arrays of vertically polarized dipoles and parasitic elements. In this paper, a novel SPA design is proposed, which is based on multiple switches employed on the body of horizontally polarized elements (one active and two parasitics). Design considerations are discussed and numerical results are illustrated. Furthermore, a simple diversity scheme is proposed, based on the novel SPA design. Superior performance of the proposed array, relative to simple non-diversity reception schemes, is indicated by simulation results. Stelios A. Mitilineos was born in Athens, Greece, in 1977. He received the Diploma in electrical and computer engineering from the National Technical University of Athens (NTUA), Greece, in October 2001. He is currently working towards his Ph.D. degree in electrical engineering at the same university. His research interests include antennas and propagation, smart antennas and mobile communications, channel estimation and location detection algorithms, MIMO systems and microwave components. Anna E. Andreoudi was born in Thessalonica, Greece, in 1977. She received the Diploma in electrical and computer engineering from the National Technical University of Athens, in 2004. Her research interests include electromagnetic waves propagation and scattering, antenna design and adaptive arrays, wireless communications and wireless mobile networks. Christos N. Capsalis was born in Nafplion, Greece in 1956. He received the Diploma in electrical and mechanical engineering from the National Technical University of Athens in 1979 and the B.S. degree in economics from the University of Athens in 1983. He obtained the Ph.D. degree in electrical engineering from NTUA in 1985. He is currently a Professor at the department of Electrical and Computer Engineering in NTUA. His current scientific activity concerns satellite and mobile communications, antenna theory and design, and electromagnetic compatibility.     

Silicon technologies for applications up to millimetre-waves: Some design guidelines

This paper presents some guidelines for the design of silicon circuits, which are able to achieve state of the art performances in the microwave frequency range despite their integration with a standard technology. Firstly, we point out the benefits which may be expected from the large number of available metallic layers, and which make possible the implementation of highly integrated and low loss interconnects and passives. Next, we emphasize the advantages of microwave differential structures: without any increase of the circuit complexity, a very well balanced behaviour can be reached leading to a strong attenuation of common mode parasitic signals. Finally, the interest and the feasibility of mixed-mode circuits (analog with digital) are demonstrated through dedicated designs for microwave frequency synthesis. Christophe Viallon received the M.S. degree and the Ph.D. degree in electrical engineering from Paul Sabatier University, Toulouse, France in 1999 and 2003 respectively. From 2000 to 2004 he was with the Laboratory of Analysis and Architecture of Systems (LAAS), Toulouse, France, where he was conducting research on the optimization of differential circuit topologies for millimeter-wave applications using SiGe BiCMOS technologies. Since 2005, he is an associate professor at Paul Sabatier University, and his researches at the LAAS laboratory are mainly focused on nonlinear microwave integrated circuit design and above-IC passive elements development. éric Tournier was born in Saint-Jean d’Angely, France, in 1970. He received the Engineer degree and the Ph.D. degree both from the Institut National des Sciences Appliqu, Toulouse, France, in 1993 and 1998 respectively. Since September 1998, he has been an associate professor of electrical engineering at the university of Toulouse, and a researcher at the Laboratoire d’Analyse et d’Architecture des Systèmes (LAAS). He has worked on low frequency analog, digital and smart-power integrated circuits design, and is now involved in microwave circuits design methodologies on silicon technologies for telecommunication ICs. He currently works on digital design applied to high frequency synthesis (frequency dividers, phase/frequency detectors and direct digital synthesis (DDS)), and analog design using BAW devices. Thierry Parra was born in August 1964. He received the Ph.D. degree in electronics engineering and the accreditation to supervise research in 1991 and 1999, respectively, both from the Paul Sabatier University (UPS), Toulouse, France. He joined the LAAS-CNRS in 1991, and since 2002 he is Professor of electrical engineering. His research interests are currently on microwave components and new materials characterisation and modelling, and on optimisation and design of microwave integrated circuits, up to the millimeter wave frequency range.     

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.     

A Data-Aided Symbol Timing and Frequency Offset Estimation Algorithm for OFDM Systems

In this paper the problem of data-aided symbol timing and frequency offset estimation in OFDM systems is considered. A synchronization scheme based on a pilot symbol containing two identical parts obtained by transmitting BPSK data symbols on the even subcarriers and setting zero on the remaining subcarriers is proposed. In this case, if the number of subcarriers is sufficiently large, the pilot symbol can be modeled as a noncircular (NC) complex Gaussian random vector (CGRV). By exploiting the joint probability density function of NC-CGRVs, the joint maximum likelihood estimator for the parameters of interest is derived. Since its implementation complexity is high, a simpler synchronization scheme is obtained. Moreover, refined symbol timing and frequency offset estimators, that assure relevant performance in multipath channels, are proposed. T. Fusco was born in Naples, Italy, on March 22, 1977. She received the Dr. Eng. degree (summa cum laude) in electronic engineering from the Second University of Napoli in 2002. Since November 2002 she has been a Ph.D. student at the Department of Electronic and Telecommunication Engineering of the University of Napoli Federico II. Her current research and study interests lie in the area of statistical signal processing, with emphasis on parameter estimation problems in the context of OFDM communications. M. Tanda was born in Aversa, Italy, on July 15, 1963. He received the Dr. Eng. degree (summa cum laude) in electronic engineering in 1987 and the Ph.D. degree in electronic and computer engineering in 1992, both from the University of Napoli Federico II. Since 1995, he has been an Appointed Professor of Signal Theory an the University of Napoli Fe-de-ri-co II. Moreover, he has been an Appointed Professor of Electrical Communications (from 1996 until 1997) and Telecommunication Systems (from 1997) at the Second University of Napoli. He is currently Associate Professor of Signal Theory at the University of Napoli Federico II. His research activity is in the area of signal detection and estimation, multicarrier, and multiple access communication systems.     

Sine-Wave Signal Characterization Using Square-Wave and ΣΔ-Modulation: Application to Mixed-Signal BIST

This paper presents a method for extracting, in the digital domain, the main characteristic parameters of an analog sine-wave signal. It is based on a double-modulation, square-wave and sigma-delta, together with a simple Digital Processing Algorithm. It leads to an efficient and robust approach very suitable for BIST applications. In this line, some considerations for on-chip implementation are addressed together with simulation results that validate the feasibility of the proposed approach.Diego Vázquez was born in El Coronil, Sevilla, Spain, in 1966. He received the Licenciado en Física degree in 1989 and the Doctor en Ciencias Físicas degree in 1995, both from the University of Sevilla, Spain. Since 1990, he has been with the Departamento de Electrónica y Electromagnetismo, University of Sevilla, where he is a Associate Professor, and also with the Instituto de Microelectrónica de Sevilla, Centro Nacional de Microelectrónica (IMSE-CNM-CSIC), Sevilla, Spain. He has published about 100 papers in international journals, books and major conferences. In 1992 he won the Best Paper Award of the 10th IEEE VLSI Test Symposium. His research interests are in the fields of design, fault tolerance, test, and design for testability of analog and mixed-signal circuits.Gloria Huertas was born in Sevilla, Spain, in 1974. She received the Licenciado en Física degree in 1997 and the Ph.D. in 2004, both from the University of Sevilla, Spain. Since then, she has been with the Departamento de Electrónica y Electromagnetismo, University of Sevilla, where she is Assistant Professor, and also with the Instituto de Microelectrónica de Sevilla, Centro Nacional de Microelectrónica (IMSE-CNM-CSIC), Sevilla, Spain. Her research focuses on designing electronic mixed-signal circuits and systems including techniques for testability.África Luque was born in Zamora (Spain) in 1977. She received the Licenciado en Física degree in 2000 from the University of Sevilla, Sevilla, Spain. She is with the Departamento de Electrónica y Electromagnetismo, University of Sevilla, and also with the Instituto de Microelectrónica de Sevilla, Centro Nacional de Microelectrónica (IMSE-CNM-CSIC), Sevilla, Spain, where she is currently pursuing the Ph.D. degree. Her research focuses on the design and test of mixed-signal circuits including Silicon-On-Insulator technologies.Manuel J. Barragan was born in Sevilla, Spain, in 1980. He received the Licenciado en Física degree in 2003 from the University of Sevilla, Sevilla, Spain. He is currently pursuing the Ph.D. degree from the Instituto de Microelectrónica de Sevilla (IMSE, CNM) on the topics of test and design for testability of analog and mixed-signal circuits.Gildas Leger was born in St. Brieuc, Côtes dArmor, France, in 1976. He received the Ingénieur en Physique degree in 1999 from the National Institute of Applied Sciences (INSA) of Rennes, France.He is currently pursuing the Ph.D. degree from the Instituto de Microelectrónica de Sevilla (IMSE, CNM). His research focuses on designing electronic mixed-signal circuits and systems including techniques for testability, specially in the domain of analog to digital conversion.Adoración Rueda joined the Department of Electronics and Electromagnetism at the University of Seville in 1976 as Assistant Professor, and obtained the Ph.D. degree in 1982. From 1984 to 1996 she was Associate Professor in that Department, where now holds the position of Full Professor in Electronics. In 1989 she became researcher at the Department of Analog Design of the National Microelectronics Center (CNM), now Institute of Microelectronics at Seville (IMSE).She has participated in several research projects financed by the Spanish CICYT and by different programs of the European Community. She has published about 135 papers in international journals, books and major conferences. In 1992 she won the Best Paper Award of the 10th IEEE VLSI Test Symposium. Her research interests are currently focused on the topics of Design and Test of Analog and Mixed-signal Circuits, Behavioral Modeling of Mixed-signal Circuits, and development of CAD tools.Jose Luis Huertas received the Licenciado en Física degree nd the Doctor en Ciencias Físicas degrees in 1969 and 1973, respectively, both from the University of Sevilla, Spain.From 1970 to 1971, he was with the Philips International Institute, Eindhoven, The Netherlands, as a postgraduate student. Since 1971, he has been with the Departamento de Electrónica y Electromagnetismo, University of Sevilla, Spain, where he is a Full Professor. He is also the Director of the Instituto de Microelectrónica de Sevilla, Centro Nacional de Microelectrónica de Sevilla, Seville, Spain. His current interests include the design and testing of analog/digital integrated circuits, computer-aided IC analysis and design, fuzzy logic, nonlinear microelectronics, and neural networks.     

Training Sequence Aided Signature Waveform Estimation

In code division multiple access channels multiuser detection techniques are known to be effective strategies to counter the presence of multiuser interference towards improving spectral efficiency. Generally, multiuser detectors can provide excellent performance only when the signature waveforms of all users are precisely known. Hence, the estimation of signature waveforms is a challenging issue in mobile communication systems. In this paper, we compare the performance of two short training sequence aided signature waveform estimators. One is maximum likelihood type signature waveform estimator that requires the knowledge of spreading sequences and short training sequences. The other estimator is recently proposed based on subspace method and requires the knowledge of training sequences only. Through the simulations, we show the signature waveform estimation performance of both systems and the effect of the estimation error on the performance of a multiuser detector. The complexity comparisons of both systems are also given. We use the term “signature waveform” to refer to the convolution of the channel and the spreading code throughout the paper. Hasan AMCA was born in 1961 in Nicosia-Cyprus. He graduated from the Higher Technological Institute in Magosa – Cyprus (which is renamed later as Eastern Mediterranean University). He joined EMU in 1985 after receiving a M.Sc. (Digital Signal Processing) degree from the University of Essex in England (1985). He took his Ph.D. (Mobile Communications) from the University of Bradford where he was on a Commonwealth scholarship. He has been teaching in the Electrical and Electronic Engineering Department of Eastern Mediterranean University since 1993 where he also served as the Vice Chairman from Spring 1998 to Spring 2000. He has been appointed as the Director of the School of Computing and Technology of the EMU since Spring 2000. His research interests include Multi User Detection of CDMA signals, Adaptive Equalisation, Multi Carrier Systems, Mobile Radio Systems and Networks, Internet and Information Technology Applications in Education. Ahmet Rizaner was born in Larnaca, Cyprus, on January 31, 1974. He received the B.S. and M.S. degrees in Electrical and Electronics Engineering from the Eastern Mediterranean University, Famagusta, North Cyprus, in 1996 and 1998, respectively. He completed his PhD. degree in Electrical and Electronic Engineering in Eastern Mediterranean University and joined Eastern Mediterranean University as a lecturer in 2004. He is lecturing in the School of Computing and Technology. His main research interests include CDMA communications, adaptive channel estimation, and multiuser detection technique. Kadri Hacioğlu was born in Nicosia, Cyprus. He received the B.Sc., M.Sc., and Ph.D. degrees in electrical and electronic engineering from the Middle East Technical University, Ankara, Turkey, in 1980, 1984, and 1990, respectively. After his two-year military service, in 1992, he joined the faculty of Eastern Mediterranean University, Magosa, North Cyprus, as an Assistant Professor, and became an Associate Professor in 1997. While there, he taught several classes on electronics, digital communications, speech processing and neural networks. During this time, he conducted research on applying fuzzy logic, neural networks, and genetic algorithms to signal processing and communications problems. From 1998 to 2000, he was a Visiting Professor in the Department of Computer Science, University of Colorado, Boulder. Here, he taught classes on neural networks and continued his research. Since 2000, he has been a Research Associate at the Center for Spoken Language Research, University of Colorado. He has authored or coauthored numerous papers and supervised a dozen M.Sc./Ph.D. theses. His current research interests are concept-based language modeling, speech understanding, natural language generation, and search methods in speech recognition/understanding. He also does research on multiuser detection and equalization in CDMA systems. Ali Hakan Ulusoy was born in Eskişehir, Turkey, on June 3, 1974. He graduated from the double major program of the department of Electrical and Electronic Engineering and department of Physics in Eastern Mediterranean University as the first rank student of Faculty of Engineering in 1996. He received his M.S. degree in Electrical and Electronic Engineering in Eastern Mediterranean University in 1998. He completed his Ph.D. degree in Electrical and Electronic Engineering in Eastern Mediterranean University and joined Eastern Mediterranean University as a lecturer in 2004. He is lecturing in the School of Computing and Technology. His current research interests include receiver design, multi-user detection techniques, blind and trained channel estimation in Code Division Multiple Access (CDMA).     

Repacking on Demand for Hierarchical Cellular Networks

In mobile telecommunications operation, radio channels are scarce resources and should be carefully assigned. One possibility is to deploy the hierarchical cellular network (HCN). This paper studies a HCN channel assignment scheme called repacking on demand (RoD). RoD was originally proposed for wireless local loop networks. We expend this work to accommodate mobile HCN. A simulation model is proposed to study the performance of HCN with RoD and some previously proposed schemes. Our study quantitatively indicates that RoD may significantly outperform the previous proposed schemes. Hsien-Ming Tsai was born in Tainan, Taiwan, R.O.C., in 1973. He received the double B.S. degrees in Computer Science & Information Engineering (CSIE) and Communication Engineering, the M.S. degree in CSIE, and the Ph.D. degree in CSIE from National Chiao-Tung University (NCTU), Taiwan, in 1996, 1997, and 2002, respectively. He is currently a research specialist in Quanta Research Institute, Quanta Computer Inc. His research interests are in the areas of cellular protocols (UMTS/GPRS/GSM/DECT), cellular multimedia (MPEG-4 Audio/Speech), and embedded systems. He is an IEEE member. Ai-Chun Pang was born in Hsinchu, Taiwan, R.O.C., in 1973. She received the B.S., M.S. and Ph.D. degrees in Computer Science and Information Engineering from National Chiao Tung University (NCTU) in 1996, 1998 and 2002, respectively. She joined the Department of Computer Science and Information Engineering, National Taiwan University (NTU), Taipei, Taiwan, as an Assistant Professor in 2002. Her research interests include design and analysis of personal communications services network, mobile computing, voice over IP and performance modeling. Yung-Chun Lin was born in Kaohsiung, Taiwan, R.O.C., in 1978. He received the B.S. and M.S. degrees in Computer Science and Information Engineering (CSIE) from National Chiao-Tung University (NCTU), Taiwan, in 2001, 2003, respectively. He is currently pursuing the Ph.D. degree in CSIE. His research interests include design and analysis of a personal communications services network, the cellular protocols (UMTS/GPRS/GSM), and mobile computing. Yi-Bing Lin received his BSEE degree from National Cheng Kung University in 1983, and his Ph.D. degree in Computer Science from the University of Washington in 1990. From 1990 to 1995, he was with the Applied Research Area at Bell Communications Research (Bellcore), Morristown, NJ. In 1995, he was appointed as a professor of Department of Computer Science and Information Engineering (CSIE), National Chiao Tung University (NCTU). In 1996, he was appointed as Deputy Director of Microelectronics and Information Systems Research Center, NCTU. During 1997-1999, he was elected as Chairman of CSIE, NCTU. His current research interests include design and analysis of personal communications services network, mobile computing, distributed simulation, and performance modeling. Dr. Lin has published over 150 journal articles and more than 200 conference papers. Lin is an Adjunct Research Fellow of Academia Sinica, and is Chair Professor of Providence University. Lin serves as consultant of many telecommunications companies including FarEasTone and Chung Hwa Telecom. Lin is an IEEE Fellow and an ACM Fellow.     

A Subcarrier Allocation Algorithm for Efficiently Reducing Power in Multiuser OFDM Systems

Resource allocation in multiuser OFDM systems is a complex nonlinear optimization problem. In order to avoid direct solution, based on the analytical results of the problem of minimizing the total transmit power, a two-step subcarrier allocation algorithm is presented. The algorithm reduces the total transmit power by reducing the achievable minimum transmit power value required by each user. Subcarriers are allocated in the algorithm according to the data rate required by users and the channel characteristics. The required number of subcarriers allocated to users does not need to be known in advance. The allocation process consists of two steps: basic subcarrier allocation and residual subcarrier allocation. Numerical results demonstrate that the proposed algorithm can reduce the total transmit power effectively. Handong Gong was born in 1974. He received the B.S. degree in auto control and the M.S. degree in physical electronic, and the Ph.D. degree in communication and information system from South China University of Technology in 1996, 2002 and 2006 respectively. He is now a lecturer in Shenzhen Institute of Information Technology. His main research interest include OFDM signal process, linearization technique for amplifier and mobile communication technologies. Wu Ye was born in 1938. Now he is a professor and Ph. D. advisor at South China University of Technology. His research interests include queuing theory and its application in communication networks, mobile communication technologies and video process. Suili Feng was born in 1955. Now he is a professor and doctor supervisor at South China University of Technology. His research interests include theory and technology of communication network, key technologies of mobile communication and embedded system. Hui Song was born in 1980. She received doctor’s degree from South China University of Technology in communication and information system in 2005. Now she is a lecturer in South China Normal University. Her research interests include signal process, flow control and optimization.     

Blind Multiuser Detection for Long Code Multipath DS-CDMA Systems with Bayesian MC Techniques

This paper presents an efficient Bayesian blind multiuser receiver for long code multipath CDMA systems. The proposed receiver employs the adaptive sampling method for the Bayesian inference procedure to estimate the data symbols and multipath parameters. Compared to the other reported Bayesian Monte Carlo receivers for long code multipath CDMA systems, the proposed one achieves a faster convergence and a lower computational complexity to attain comparable performance. Simulation results are presented to demonstrate the effectiveness of the proposed Bayesian blind multiuser receiver. Qian Yu received the B. S. and M. S. degree in control theory and applications in 1997 and 2000, respectively, from Northwestern Polytechnical University (NWPU), Xian, China. She is currently working toward the Ph.D. degree in the Division of Information Engineering of EEE, Nanyang Technology University, Singapore. Her general research interests are in the area of signal processing for wireless communication systems. Dr Guoan Bi received a B.Sc degree in Radio communications, Dalian University of Technology, PRC, 1982, M.Sc degree in Telecommunication Systems and Ph.D degree in Electronics Systems, Essex University, UK, 1985 and 1988, respectively. Since 1991, he has been with the school of Electrical and Electronic Engineering, Nanyang Technological University, Singapore. His current research interests include DSP algorithms and hardware structures and digital signal processing for communications. Dr. Liren Zhang is currently an Associate Professor in the School of Electrical and Electronic Engineering, Nanyang Technological University (NTU). He received his B.Eng. degree from Shandong University in 1982, M.Eng degree from the University of South Australia in 1988, and Ph.D from the University of Adelaide, Australia in 1990, all in electrical engineering. From 1990 to 1995 he was a Senior Lecturer in the Department of Electrical and Computer Systems Engineering, Monash University, Australia.Dr Zhang has vast experience as an engineer, academic and researcher in the field of multimedia communications, switching and signaling, teletraffic engineering, network modeling and performance analysis for ATM networks, high speed data networks, mobile networks, satellite networks and optical networks. He has published more than 100 research papers in international journals and conferences. He has been the associate editor for the Journal of Computer Communications since 2000.     

A VLSI Implementation of Low Power, Low Data Rate UWB Transceiver for Location and Tracking Applications

A low power, low data rate ultra wideband (UWB) impulse radio transceiver for location and tracking applications is presented in this paper. The UWB receiver is based on a non-coherent, energy collection approach, which makes the receiver highly independent of the shape of the transmitted waveform. The UWB signal is generated by a pulse generator and band-pass filter fixing the signal bandwidth to 1 GHz in the band from 3.1 GHz to 4.1 GHz. The modulation scheme used in this time division multiple access system (TDMA) is Binary Pulse Position Modulation (BPPM). In this paper the system concept, system architecture and RF parts of the VLSI implementation are peresented. The transceiver is implemented in a 0.35 μm SiGe process provided by Austria Microsystems. Sakari Tiuraniemi was born in Kolari, Finland, on March 10, 1977. He received his M.Sc. degree in 2003 in electrical engineering from the University of Oulu, Finland, where he then continued his research on transceiver integration and implementation issues for two years. In 2005 he joined the CERN in Geneva, Switzerland, where he is working towards the PhD degree in electrical engineering. His current research focuses on detector readout electronics for high energy physics applications. Lucian Stoica was born in Roman, Romania, on December 8, 1975. He received the M.S. degree in electrical engineering from the Technical University of Iasi, Romania, in 2000. He was with Telecommunications Department at the Technical University of Iasi from 2000 to 2003. As a teaching assistant he was involved in development of digital design and FPGA prototyping. In 2003, he joined Centre for Wireless Communications, University of Oulu, Oulu, Finland where he is working towards the PhD degree in electrical engineering. His current research focuses on low complexity SiGe BiCMOS circuit transceivers design for wireless communications, particularly on ultrawideband impulse radio systems. Alberto Rabbachin received the M.S. from the University of Bologna, Italy, in 2001. In 2001, during his undergraduate studies, he visited the Centre for Wireless Communications, University of Oulu, Finland. In 2002 he joined Agilent Technologies for an internship and since 2003 he is working towards the PhD degree at the Centre for Wireless Communications. His research interests include UWB systems with emphasis on receiver structures, synchronization and ranging techniques. Ian Oppermann was born in Maryborough, Australia, in 1969. He completed a BSc, BE and PhD at the University of Sydney Australia in 1990, 1992 and 1997, respectively. His PhD was related to physical layer aspects of novel spread spectrum/CDMA systems. In 1996 he founded SP Communications, a company which developed network planning tools for 3G mobile systems and IP cores for WLAN chipsets. He became a Docent (Adjunct Professor) at the University of Oulu, Finland in 2001 and subsequently joined the Centre for Wireless Communications (CWC) in 2002 as Assistant Director, becoming Director in 2003. From the beginning of 2005 is the acting Director for Short Range Communications Research at CWC. His main research interests are spread spectrum systems and UWB. Dr. Oppermann has co-edited several books, holds several patents for wireless communications and has over 80 publications in international journals and conferences.     

UWB Multiple Access Communication System

Recently, the emerging Ultra-Wideband (UWB) impulse technology has found numerous applications in the civil as well as the military sectors. In this paper, an UWB multi-user communication system is studied. In a previous work, two systems (DS–CDMA–UWB and Gegenbauer–UWB) were compared in a rather simple case: only two users were considered, and a perfect synchronization between each receiver and transmitter for the two users was assumed. In the present paper, a more general case is studied. Different synchronous (different users detected at the same time or with constant delays) and asynchronous (each user transmitting independantly of other) scenarios are introduced. The interferences between users are also taken into account (for two users and more). Two systems are described and analyzed and their performance in terms of Bit Error Rate (BER), synchronization errors and users interference is studied by simulation. The first system, which is only based on orthogonal UWB waveforms called Modified Gegenbauer functions (MGF), gives a satisfactory multi-user detection in the synchronous case only. The second one uses an hybrid coding technique: an UWB orthogonal coding is associated to a spread spectrum DS–CDMA (Direct Sequence Code Division Multiple Access) technique (in fact a combination of the two systems sudied in the previous work). This allows an efficient multi-user detection in the asynchronous case.     

Electronic Implementation of Multirate Sigma-Delta Modulators Using CMOS Technologies

Multirating has been recently proposed to reduce the frequency rate of the first integrator(s) of a single-loop, or the first stage(s) of a cascade, Sigma-Delta modulator (SDM). This is a promising technique for the design of high speed, low-power modulators, as the first integrator (or stage) in the chain primarily determines the performances of the modulator, as well as its power consumption. This paper presents the first implementation of a 2nd-order multirate SDM, showing different circuit solutions. The experimental results obtained with a prototype in a standard 0.6 μm CMOS technology shows that different clock rates can be selected for each integrator of a SDM. Alfredo Pérez Vega-Leal was born in Seville, Spain. He received the Telecommunications Engineering and Ph.D. degrees from the University of Seville, Seville, Spain, in 1998 and 2003, respectively. Since 1995, he has been with the Department of Electronic Engineering, School of Engineering, University of Seville, as research student and became an Associate Professor in 1999. His research interests are related to low-voltage low-power analog circuit design, A/D and D/A conversion. Francisco Colodro was born in Peal de Becerro (Jaén), Spain, in 1968. He received the Ingeniero de Telecomunicación degree from the University of Vigo, Vigo, Spain, in 1992, and the Ph.D. degree from the University of Sevilla, Sevilla, Spain, in 1997. In 1992 he joined the Department of Electronics Engineering, University of Sevilla, where he is currently and Associate Professor. His research interests are in the architectural study of Σ Δ modulators, the implementation of ADCs based on Σ Δ modulators, and application of electronic circuits and systems to communication. Marta Laguna was born in Seville, Spain. She received the Telecommunications Engineering degree from the University of Seville in 2002. She is currently working toward the Ph.D. degree. Her doctoral work focuses on the design of continuous-time sigma-delta modulators. Since 2001, she has been with the Department of Electronic Engineering, School of Engineering, University of Seville, as research student and became an assistant teacher in 2004. Her research interests are high-speed analog-to-digital converters and sigma-delta modulators. Antonio Torralba (M'89–SM'02) was born in Sevilla, Spain, in 1960. He received the electrical engineering and Ph.D. degrees from the University of Sevilla in 1983, and 1985, respectively. Since 1983 he has been with the Department of Electronics Engineering, School of Engineering, University of Sevilla, where he has been Associate Professor in 1987, and Full Professor since 1996, leading a research group on mixed signal design. In 1999 he made a short stay at the Department of Electrical Engineering, NMSU, and he is presently in the Department of Electrical Engineering, TAMU for a Sabbatical stay. His interests include low-voltage analog circuits and systems, analog to digital conversion, Σ Δ modulators, and electronic circuits and systems with application to control and communication. In these fields he has published around 40 journal papers and more than 100 conference papers, and he holds 2 international patents.     

Performance Evaluation of a Multi-band UWB Location and Communication System Based on Modified Gegenbauer Functions

Ultra wide band (UWB) may offer very efficient solutions for various communication and sensing applications. Two approaches have emerged, which meet all the communication requirements: impulse and multi-band systems. The present work is concerned in the second approach. So, we propose to use orthogonal functions called Modified Gegenbauer Functions (MGF) in a multi-band UWB system occupying the 3–6 GHz frequency band. Different scenarios are studied and compared in the scope of a system offering communication and location capabilities for subway trains. In order to evaluate the performance of the proposed system, the bit error rate (BER) values for communication are calculated and analyzed in the presence of multi-user interference, assuming asynchonous users. It is shown that Gegenbauer functions offer the performance required for our multi-band UWB communication and location system.

G729 Voice Decoder Design

Embedded digital signal processing (DSP) systems are usually associated with real time constraints and/or high data rates such that fully software implementations are often not satisfactory. In that case, mixed hardware/software implementations are to be investigated. This paper presents the design of a HW/SW G.729 voice decoder dedicated to embedded systems. The decoder has been built around, on the one hand a reconfigurable digital circuit (FPGA) to achieve the so called IP hardware part—the autocorrelation computation—using a linear systolic array, and on the other hand a digital signal processor (DSP) for the remainder of the algorithm. Apart such an implementation is typically driven by the use of reusable component (IP) it is of great interest for new G729-based applications such as Voice over IP (VoIP) for example. It results in an overall reduction of the execution time per frame. Another interesting point is the design of a parameterizable autocorrelation block which can be useful for a wide range of applications such as GSM 13 Kbit/s, APC 9.6 Kbit/s and G723 6.3 Kbit/s and 5.3 Kbit/s. In the G729 context and using a V50 Virtex FPGA, the execution time of this function is 10 times faster than a TMS320C6201 DSP implementation. Fatma Sayadi is Ph.D. student at Faculty of Sciences, Monastir, Tunisia in collaboration with the LESTER Laboratory, University de Bretagne Sud, Lorient, France. She is a member of Laboratory of Electronics and Micro-Electronics. His researches interest, the implementation of Digital Signal, high level design using VHDL language, Hardware/Software Co-design. Emmanuel Casseau received his Ph.D Degree in Electrical Engineering in 1994. He is currently an Associate Professor in the Electronic Department at the University de Bretagne Sud, Lorient, France. He is also in charge of the IP project of the Lester Lab., University de Bretagne Sud. His research interests include system design, high-level synthesis, virtual components and SoCs. Mohamed Atri born in 1971, received his Ph.D. Degree in Micro-electronics from the Science Faculty of Monastir in 2001. He is currently a member of the Laboratory of Electronics & Micro-electronics. His research includes Circuit and System Design, Network Communication, IPs and SoCs. Mehrez Marzougui received the B.Sc. degree from University of Science and Technology (electronic option), Monastir, Tunisia, and the M.Sc. degree in electronic from the same university in 1996 and 1998 respectively. Since 1998, he has been a Ph.D. candidate in Electronic and Micro-electronic laboratory at the University of Sciences and Technology, Monastir, Tunisia. His research interests include hardware/software co-verification and high-level synthesis. Rached Tourki was born in 1948. He received the B.S. degree in Physics (Electronics option) from Tunis University, in 1970; the M.S. and the Doctorat de 3eme cycle in Electronics from Institut d'Electronique d'Orsay, Paris-south University in 1971 and 1973 respectively. From 1973 to 1974 he served as microelectronics engineer in Thomson-CSF. He received the Doctorat d'etat in Physics from Nice University in 1979. Since this date he has been professor in Microelectronics and Microprocessors with the physics department, Faculte des Sciences de Monastir. Eric Martin born in 1961, is a Full Professor at the University of South Brittany in Lorient, France. His interest includes the implementation of Digital Signal and Image Processing and high-level design methods for dedicated circuits.     

Capacity of Multiservice WCDMA Networks with Variable GoS

Traditional definitions of capacity of CDMA networks are either related to the number of calls they can handle (pole capacity) or to the arrival rate that guarantees that the rejection rate (or outage) is below a given fraction (Erlang capacity). We extend the latter definition to other quality of service (QoS). We consider best-effort (BE) traffic sharing the network resources with real-time (RT) applications. As is often the case in CDMA systems, we assume that the BE traffic access is done using a time-shared channel (such as the HDR or the HSDPA). BE applications can adapt their instantaneous transmission rate to the available one and thus need not be subject to admission control or outages. Their meaningful QoS is the average delay (i.e. the sojourn time). The delay aware capacity is then defined as the arrival rate of BE calls that the system can handle such that their expected delay is bounded by a given constant. We compute in this paper both the blocking probability of the RT traffic having an adaptive Grade of Service (GoS) as well as the expected delay of the BE traffic for an uplink multicell WCDMA system. This yields the Erlang capacity for former and the delay capacity for the latter. A shorter version of this work was presented at the IEEE WCNC 2003 in New Orleans, LA, USA. Nidhi Hegde received the B.Sc. degree with specialization in Biochemistry (1995) from the University of Alberta, Canada, and the M.Sc (1997) in Computer Science and the Ph.D (2000) degree in Telecommunications and Computer Networking, both at the University of Missouri-Kansas City, USA. She has been with France Telecom R&D since January 2005. Her research interests include performance evaluation of networks, with an emphasis on wireless networks. E. Altman received the B.Sc. degree in electrical engineering (1984), the B.A. degree in physics (1984) and the Ph.D. degree in electrical engineering (1990), all from the Technion-Israel Institute, Haifa. In (1990) he further received his B.Mus. degree in music composition in Tel-Aviv university. Since 1990, he has been with INRIA (National research institute in informatics and control) in Sophia-Antipolis, France. His current research interests include performance evaluation and control of telecommunication networks and in particular congestion control, wireless communications and networking games. He is in the editorial board of several scientific journals: Stochastic Models, JEDC, COMNET, SIAM SICON and WINET. He has been the (co)chairman of the program committee of several international conferences and workshops (on game theory, networking games and mobile networks). More informaion can be found at