Radio Resource Management with Utility and Pricing for Wireless LAN Hot-Spots

We investigate Wireless LAN hot-spots based on the IEEE 802.11b protocol, considering technical and economic issues of the Radio Resource Allocation. Firstly, we discuss how to model the trade-off between perceived QoS and paid price in the users' request, so as to represent the users as choosing the most satisfactory allocation, determined by service requirements and willingness to pay. After the setup of the users' requests, the multiple medium access mechanism is considered and the network performance is evaluated and discussed. Thus, we investigate the provider's task of having a suitable price policy which gives a satisfactory income and efficiently exploit network capacity. This is also dependent on a price setting that is accepted by the users and optimises resource usage. Finally, we study how the multiple access scheme specified in the IEEE 802.11b protocol combines users' requests to a final allocation, and identify possibilities of improvement for the inherent inefficiencies arising from overload. Leonardo Badia was born in Ferrara, Italy, in 1977. He received the MS Degree in Electrical Engineering and the PhD in Information Engineering both from the University of Ferrara, Italy, in 2000 and 2004 respectively. In 2001 he joined the Department of Engineering of the University of Ferrara, where he is a currently a post-doc researcher. During 2002 and 2003 he was on leave at the Royal Institute of Technology of Stockholm, Sweden. His research interests include energy efficient Ad Hoc Networks, transmission protocol modelling, Admission Control and economic modelling of Radio Resource Management for Wireless Networks. Michele Zorzi was born in Venice, Italy, in 1966. He received the Laurea Degree and the Ph.D. in Electrical Engineering from the University of Padova, Italy, in 1990 and 1994, respectively. During the Academic Year 1992/93, he was on leave as a graduate student at the University of California, San Diego (UCSD), where he did research on multiple access in mobile radio networks. In 1993, he joined the faculty of the Dipartimento di Elettronica e Informazione, Politecnico di Milano, Italy. After spending three years with the Center for Wireless Communications at UCSD, in 1998 he joined the School of Engineering of the University di Ferrara, Italy. Since November 2003, he has been on the faculty at the Information Engineering Department of the University of Padova. His present research interests include performance evaluation in mobile communications systems, random access in mobile radio networks, ad hoc and sensor networks, and energy constrained communications protocols. Dr. Zorzi is the Editor-In-Chief of the IEEE Wireless Communications Magazine, and currently serves on the Editorial Boards of the IEEE Transactions on Communications, the IEEE Transactions on Wireless Communications, the IEEE Transactions on Mobile Computing, the Wiley Journal of Wireless Communications and Mobile Computing and the ACM/URSI/ Kluwer Journal of Wireless Networks.     

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

The main goal of this paper is to provide routing–table-free online algorithms for wireless sensor networks (WSNs) to select cost (e.g., node residual energies) and delay efficient paths. As basic information to drive the routing process, both node costs and hop count distances are considered. Particular emphasis is given to greedy routing schemes, due to their suitability for resource constrained and highly dynamic networks. For what concerns greedy forwarding, we present the Statistically Assisted Routing Algorithm (SARA), where forwarding decisions are driven by statistical information on the costs of the nodes within coverage and in the second order neighborhood. By analysis, we prove that an optimal online policy exists, we derive its form and we exploit it as the core of SARA. Besides greedy techniques, sub–optimal algorithms where node costs can be partially propagated through the network are also presented. These techniques are based on real time learning LRTA algorithms which, through an initial exploratory phase, converge to quasi globally optimal paths. All the proposed schemes are then compared by simulation against globally optimal solutions, discussing the involved trade–offs and possible performance gains. The results show that the exploitation of second order cost information in SARA substantially increases the goodness of the selected paths with respect to fully localized greedy routing. Finally, the path quality can be further increased by LRTA schemes, whose convergence can be considerably enhanced by properly setting real time search parameters. However, these solutions fail in highly dynamic scenarios as they are unable to adapt the search process to time varying costs. Michele Rossi was born in Ferrara, Italy on October 30th, 1974. He received the Laurea degree in Electrical Engineering (with honors) and the Ph.D. degree in Information Engineering from the University of Ferrara in 2000 and 2004, respectively. Since 2000 he has been a Research Fellow at the Department of Engineering of the University of Ferrara. During 2003 he was on leave at the Center for Wireless Communications (CWC) at the University of California San Diego (UCSD), where he did research on wireless sensor networks. In November 2005 he joined the Department of Information Engineering of the University of Padova, Italy, where he is currently an Assistant Professor. Michele Rossi is currently part of the EU funded Ambient Networks and eSENSE projects. His research interests include: TCP/IP protocols over wireless networks, performance analysis of link layer retransmission techniques, routing and access selection in heterogeneous wireless networks and MAC/routing algorithms for wireless sensor networks. Michele Zorzi was born in Venice, Italy, in 1966. He received the Laurea degree and the Ph.D. degree in Electrical Engineering from the University of Padova, Italy, in 1990 and 1994, respectively. During the Academic Year 1992/93, he was on leave at the University of California, San Diego (UCSD), attending graduate courses and doing research on multiple access in mobile radio networks. In 1993, he joined the faculty of the Dipartimento di Elettronica e Informazione, Politecnico di Milano, Italy. After spending three years with the Center for Wireless Communications at UCSD, in 1998 he joined the School of Engineering of the University of Ferrara, Italy, and in 2003 joined the Department of Information Engineering of the University of Padova, Italy, where he is currently a Professor. His present research interests include performance evaluation in mobile communications systems, random access in mobile radio networks, ad hoc and sensor networks, and energy constrained communications protocols. Dr. Zorzi from 2003 to 2005 was the Editor-In-Chief of the IEEE Wireless Communications Magazine, and currently serves on the Editorial Boards of the IEEE Transactions on Communications, the IEEE Transactions on Wireless Communications, the IEEE Transactions on Mobile Computing, the Wiley Journal of Wireless Communications and Mobile Computing and the ACM/URSI/Kluwer Journal of Wireless Networks. He was also guest editor for special issues in the IEEE Personal Communications Magazine (Energy Management in Personal Communications Systems) and the IEEE Journal on Selected Areas in Communications (Multi-media Network Radios). Ramesh R. Rao was born in Sindri, India, where he completed his undergraduate work at the Regional Engineering College of the University of Madras in Tiruchirapalli, obtaining a BE (Honors) degree in Electronics and Communications in 1980. He completed his graduate work at the University of Maryland, College Park, Maryland where he received his M.S. and Ph.D. Professor Rao is currently a Professor at the University of California, San Diego (UCSD) at the department of Electrical and Computer Engineering in the Irwin and Joan Jacobs School of Engineering, where he has been a member of the faculty since 1984. Professor Rao is the former director of UCSD’s Center for Wireless Communications (CWC), and currently serves as the Qualcomm Endowed Chair in Telecommunications and Information Technologies, and as the Director of the San Diego Division of the California Institute of Telecommunications and Information Technology [Cal-(IT)²]. As Director of the San Diego Division of Cal-(IT)², he leads several interdisciplinary and collaborative projects. His research interests include architectures, protocols and performance analysis of computer and communication networks, and he has published extensively on these topics. Since 1984, Professor Rao has authored over 100 technical papers, contributed book chapters, conducted a number of short courses and delivered invited talks and plenary lectures. He is currently supervising both masters and doctoral students.     

Energy-Efficient Operation through Interference Avoidance for Interconnected Bluetooth WPANs

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

Optimization of Half-Rate Codec Assignment in GERAN

Half-Rate (HR) channel coding can be used to deal with temporary traffic peaks in Global System for Mobile Communications (GSM)/Enhanced Data Rates for Global Evolution (EDGE) Radio Access Networks. Since operators have to pay for the use of HR codecs, the number of transceivers on which HR can be used is normally limited. An algorithm that optimizes the assignment of a limited number of HR codecs in a network is presented. The final solution obtained with the greedy algorithm proposed has proved to be optimal. Subsequent application of the algorithm in a real environment shows significant performance benefits in terms of network congestion reduction in comparison to the current approach used by network operators. Matías Toril received an M.S. degree in telecommunication engineering in 1995 from the University of Málaga, Spain. Since 1997, he is on the staff of the Communications Engineering Department, where he is currently working toward a Ph.D. degree. From 2000 to 2003, he simultaneously joined the Nokia Networks Competence Team in Málaga. His research interests include optimization of mobile radio access networks and radio resource management. Ricardo Ferrer obtained his M.S. in Telecommunication from the University of Malaga in 2000. He joined the Nokia Networks Competence Team in Málaga in 2000, where he worked in control and optimization algorithms for telecommunication cellular networks. In 2003 he joined TarTec where he leads the development of a network optimization solution. Salvador Pedraza received an M.S. degree in electrical engineering in 1995 and Ph.D. in control engineering in 2000 from the University of Málaga, Spain. He joined Nokia Networks in July 2000 for three years. In June 2003 he co-founded TarTec for providing solutions and services for cellular network performance optimisation, being responsible of research and technology unit. His research interests include control and optimization techniques for mobile networks and stochastic processes theory. Volker Wille Following under graduate studies in Germany and an internship at Bell Communications Research, USA, Volker Wille carried out postgraduate studies in UK leading to a PhD degree. In Nokia, he currently is responsible for development of features that enable self-regulation of cellular networks. Juan J. Escobar obtained his M.S. in telecommunication engineering from the University of Málaga. He joined the Nokia Networks Competence Team in Málaga in 2001, where he worked in control and optimization algorithms for telecommunication cellular networks. In 2003 he joined TarTec, where he leads the development of a common framework for network performance optimization.     

Dynamic utility and price based radio resource management for rate adaptive traffic

This paper explores analytical Radio Resource Management models where the relationship between users and services is mapped through utility functions. Compared to other applications of these models to networking, we focus in particular on specific aspects of multimedia systems with adaptive traffic, and propose a novel framework for describing and investigating dynamic allocation of resources in wireless networks. In doing so, we also consider economic aspects, such as the financial needs of the provider and the users’ reaction to prices. As an example of how our analytical tool can be used, in this paper we compare different classes of RRM strategies, e.g., Best Effort vs. Guaranteed Performance, for which we explore the relationships between Radio Resource Allocation, pricing, provider’s revenue, network capacity and users’ satisfaction. Finally, we present a discussion about Economic Admission Control, which can be applied in Best Effort scenarios to further improve the performance. Part of this work has been presented at the conference ACM/IEEE MSWiM 2004, Venice (Italy). Leonardo Badia received a Laurea degree (with honors) in electrical engineering and a Ph.D. in information engineering from the University of Ferrara, Italy, in 2000 and 2004, respectively. He was a Research Fellow at the University of Ferrara from 2001 to 2006. During these years, he also had collaborations with the University of Padova, Italy, and Wireless@KTH, Royal Institute of Technology, Stockholm, Sweden. In 2006, he joined the “Institutions Markets Technologies” (IMT) Institute for Advanced Studies, Lucca, Italy, where he is currently a Research Fellow. His research interests include wireless ad hoc and mesh networks, analysis of transmission protocols, optimization tools and economic models applied to radio resource management. Michele Zorzi received a Laurea degree and a Ph.D. in electrical engineering from the University of Padova in 1990 and 1994, respectively. During academic year 1992–1993, he was on leave at UCSD, attending graduate courses and doing research on multiple access in mobile radio networks. In 1993 he joined the faculty of the Dipartimento di Elettronica e Informazione, Politecnico di Milano, Italy. After spending three years with the Center for Wireless Communications at UCSD, in 1998 he joined the School of Engineering of the University of Ferrara, Italy, where he became a professor in 2000. Since November 2003 he has been on the faculty at the Information Engineering Department of the University of Padova. His present research interests include performance evaluation in mobile communications systems, random access in mobile radio networks, ad hoc and sensor networks, energy constrained communications protocols, and broadband wireless access. He was Editor-In-Chief of IEEE Wireless Communications, 2003–2005, and currently serves on the Editorial Boards of IEEE Transactions on Communications, IEEE Transactions on Wireless Communications, Wiley’s Journal of Wireless Communications and Mobile Computing, and ACM/URSI/Kluwer Journal of Wireless Networks, and on the Steering Committee of the IEEE Transactions on Mobile Computing. He has also been a Guest Editor of special issues in IEEE Personal Communications (Energy Management in Personal Communications Systems) and IEEE Journal on Selected Areas in Communications (Multimedia Network Radios).     

A 1 V switchable CMOS LNA for 802.11A/B WLAN applications

A new dual-band, 2.4 and 5.2 GHz, combined LNA, which can operate at 1 V supply only, for WLAN application is presented. The switched transistor technique is used in the LNA. It could match the input port in two frequency bands and reduce one on-chip spiral inductor usage compared with [1, 2]. Theoretical analysis and transistor level simulation results using 0.18 μm CMOS process from Chartered Semiconductor are presented to demonstrate this idea. Wang-Chi Cheng received his B.Eng., M.Phil., and Ph.D. degrees in Electronic Engineering of the Chinese University of Hong Kong (CUHK) in 1999, 2001 and 2004. His research achievements during M.Phil. and Ph.D. studies were in the field of low voltage receiver front-end circuits design with CMOS technology. He joined the Electrical and Electronic Engineering department of Nanyang Technological University (NTU), Singapore, in May 2005 as a Research Fellow. Now, he is a Senior Engineer in charge of the UWB transceiver IC design in Hong Kong Applied Science and Technology Research Institute (ASTRI). His current research interests include 802.11 A/B WLAN and UWB transceiver design. He is also a paper reviewer of the IEEE Microwave and Wireless Components Letters. Jian-Guo Ma received his B.Sc. and M.Sc. in 1982 and 1988 respectively with honors from Lanzhou university of Chain, and Doctoral Degree in Engineering from Gerhard-Mercator University of Germany in 1996. From Jan. 1982 to March 1991, he has worked with Lanzhou university of China on RF & Microwave Engineering. Before he joined Nanyang Technological University in 1997, he was with Technical University of Nova Scotia, Canada. Now, he is a Professor of the University of Electronic Science and Technology of China. His research interests are: RFIC designs for wireless applications; RF characterization and modeling of semiconductor devices; RF interconnects and packaging; SoC and Applications; EMC/EMI in RFICs. He has published more than 150 technical papers and two books in above mentioned areas. He holds 6 patents in CMOS RFICs. He is now Associate Editor for IEEE Microwave and Wireless Components Letters. Kiat-Seng Yeo received his B.E. (Hons.) (Elect) in 1993, and Ph.D. (Elect. Eng.) in 1996 both from Nanyang Technological University, Singapore. He joined the School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore as a Lecturer in 1996, and became an Assistant Professor and an Associate Professor in 1999 and 2002, respectively. Professor Yeo provides consulting to statutory boards and multinational corporations in the areas of semiconductor devices and electronic circuit design. He has been extensively involved in the modeling and fabrication of small MOS/Bipolar integrated technologies for the last ten years. His research interests also include the design of new circuits and systems (based on scaled technologies) for low-voltage low-power applications; radio frequency integrated circuit (RF IC) design; integrated circuit design of BiCMOS/CMOS multiple-valued logic circuits, domino logic, and memories; and device characterization of deep submicrometer MOSFETs. Manh-Anh Do obtained his B.E. (Hons) (Elect.) in 1973, and Ph.D. (Elect. Eng.) in 1977 both from University of Canterbury, New Zealand. Between 1977 and 1989, he held various positions including: R & D engineer and production manager at Radio Engineering Ltd., research scientist at Fisheries Research Centre, New Zealand, and senior lecturer at National University of Singapore. He joined the School of Electrical and Electronic Engineering, Nanyang Technological University (NTU), Singapore as a senior lecturer in 1989, and obtained the Associate Professorship in 1996 and the Professorship in 2001. He has been a consultant for many projects in the Singapore electronic industry, and was the principal consultant for the design, testing and implementation of the $200 million Electronic Road Pricing (ERP) island-wide project in Singapore, from 1990 to 2001. His current research is on digital and mobile communications, RF IC design, mixed-signal circuits and intelligent transport systems. Before that, he specialsed in sonar designing, biomedical engineering and signal processing. Since 1995, he has been Head of Division of Circuits and Systems, School of EEE, NTU. He is a Fellow of IEE, UK, a Chartered Engineer (UK) and a Professional Engineer (Singapore).     

IrBurst Modelling and Performance Analysis in the Presence of Transmission Errors

IrBurst is a session/presentation layer protocol dedicated for high speed large volume information transfer over IrDA links. The protocol is developed by IrDA in order to complement the existing protocol OBEX which is best suited for small files. This paper presents a mathematical model for IrBurst over the IrDA protocol stacks taking into account the presence of bit errors and multiple simultaneously applications. The performance of IrBurst is examined considering TinyTP buffer sizes and the number of IrBurst application connections as parameters. The contribution of this work is to develop a mathematical model for IrBurst, investigate the compatibility of IrBurst to low layer protocols, as well as providing suitable design guidelines for IrDA devices for high performance of IrBurst. Pi Huang received the B.Sc. degree in Electrical and Electronic Engineering from University of Central Lancashire, U.K., in 2001, the M.Sc. degree in Telecommunications from University College London, U.K., in 2002 and the Ph.D degree in the Personal Wireless Networks and Outdoor Optical Links from Bournemouth University, U.K., in 2006. He is currently working in wireless solution division of British Telecom. His research focuses on performance modelling and analysis as well as discrete-event simulation of wireless communication protocols and wireless communication networks. He has published over 20 papers in the areas of wireless communications. Anthony C. Boucouvalas has worked at GEC Hirst Research Centre, and became Group Leader and Divisional Chief Scientist until 1987, when he joined Hewlett Packard (HP) Laboratories as Project Manager. He joined Bournemouth University in 1994 and became a Professor in Multimedia Communications in 1996, and in 1999 became Director of the Microelectronics and Multimedia Research Centre. His current research interests span the fields of wireless communications, optical fibre communications and components, multimedia communications, and human-computer interfaces, where he has published over 200 papers. He has contributed to the formation of IrDA as an industry standard and he is now a Member of the IrDA Architectures Council. He is a Fellow of Fellow of the Royal Society for the encouragement of Arts, Manufacturers and Commerce, (FRSA) and a Fellow of IEE, (FIEE). In 2002 he became a Fellow of the Institute of Electrical and Electronic Engineers (FIEEE), for contributions to optical fibre components and optical wireless communications. He is an Editor of numerous Journals and in the Organising committee of many conferences.     

13.56 MHz CMOS transceiver for RFID applications

An Amplitude Shift Keying (ASK) transceiver for RFID applications is presented in this paper. The proposed transceiver is suitable for communications with electronic devices that are powered through an inductive link. The circuit has been designed to be compatible with the communication standards ISO 14443. It operates at 13.56 MHz with a communication speed from 200 kHz up to 847 kHz. In modulation mode of operation, a solution based on programmable CMOS inverters is proposed to control the modulation depth in the range [0–100%]. The demodulator has been designed using versatile current rectifier and a simple operational transconductance amplifier stage. The proposed transceiver was implemented in a standard 0.5 μm CMOS process. The circuit covers an area of 2 mm² and the total DC power consumption is lower than 5.3 mW under 4V DC supply voltage. Stéphane Meillére has received the Engineer degree in Microelectronics from the ISEN-Toulon, Institut Supérieur d’Electronique et du Numérique, School at Toulon in 2000 and the M.Sc. and Ph.D. degrees from the University of Provence Aix-Marseille I, France, in 2000 and 2004, respectively, all in Microelectonics. From 2003 to 2005, he worked as a Research Engineer at the ISEN-Toulon. Since 2005 he joined the University of Provence as an Assistant Professor. His research interests are mainly in the design of full custom ASICs. He integrated in the same time the Integrated Circuits Design Team at the L2MP laboratory. He worked on different research project with industry. Hervé Barthélemy has received the MSc degree in Electrical Engineering in 1992 and the PhD degree in Electronics from the University of Paris XI Orsay, France in 1996. In 2002 he received the HDR degree from the University of Provence, Aix-Marseille I, France. From 1996 to 2000 he was an Assistant Professor at the Institut Supérieur d’Electronique de la Méditerranée (ISEN) in Toulon, France. Since 2000 he joined the University of Provence where is has been a full Professor in 2005. Since 2005 he has headed the Integrated Circuits Design Team at the L2MP laboratory. The team counts 12 Researchers and 20 PhD students and is involved in several research projects with industry. His research interests are mainly in the design of radiofrequency analog integrated circuits. He authored and co-authored multiple publications in international journals and conference proceeding. Michel Martin received an engineering degree in applied physics, option Micro-electronics from Ecole Nationale Supérieure de Physics in Marseille in 1991. He worked previously in ST Microelectronics, and he was involved in the design of the Smart Card Group’s product. He joined Gemplus in ’91 where he designed chips for secured smart cards memories. In 1995, he was the Co-founder of INSIDE Contactless. He was involved in the analog and EEPROM memories designs for contact and contactless chips. Michel was promoted I.C. Design Director with a team of 15 people divided on 2 Design Centers. He still maintains an active part in the chip Design. He is also the responsible for technical interface with the foundries to develop EEPROM memory bit cell, and improve the new processes dedicated the smart cards application.     

High Data Rate Alamouti Code From Field Extension

Alamouti code is the only known Orthogonal Space Time Block Code (OSTBC) with rate-1. All other known orthogonal codes have rate less than unity. The orthogonal property of OSTBCs reduces the decoding complexity to a large extent. High data rate Space Time Block Codes for arbitrary number of transmit antennas were recently proposed based on Division Algebras. But these STBCs are not orthogonal. Therefore their decoding complexity is very high. In this paper we propose high data rate Alamouti codes from field extensions for two transmit antennas. Our codes have better coding gain than the both high rate codes from division algebra and the rate-1 Alamouti code. Vishwanath R was born in Hyderabad, India in 1982. He did his B.E. in Electronics and Communications Engineering from Birla Institute Of Technology, Ranchi, India in 2002 and Master of Technology in Communications Engineering in 2005 from Indian Institute of Technology Delhi, India.. Currently he is pursuing PhD from Indian Institute of Technology Delhi, India. His research interests include Routing in Optical Networks, Signal Processing, Wireless Communications and Image Processing. He is a member of the IEEE. Bhatnagar Manav R was born in Moradabad, India in 1976. He did his B.E. in Electronics in 1997 and Master of Technology in Communications Engineering in 2005 from Indian Institute of Technology Delhi, India. He has worked as lecturer in Moradabad Institute of Technology, Moradabad, India from 1998–2003. He is currently pursuing PhD from Indian Institute of Technology Delhi, India. His research interests include Routing in Optical Networks, Signal Processing in Wireless Communications and Image Processing. He is a member of the IEEE.     

Performance of a burst-frame-based CSMA/CA protocol: Analysis and enhancement

In this paper, we develop an analytical model to evaluate the delay performance of the burst-frame-based CSMA/CA protocol under unsaturated conditions, which has not been fully addressed in the literature. Our delay analysis is unique in that we consider the end-to-end packet delay, which is the duration from the epoch that a packet enters the queue at the MAC layer of the transmitter side to the epoch that the packet is successfully received at the receiver side. The analytical results give excellent agreement with the simulation results, which represents the accuracy of our analytical model. The results also provide important guideline on how to set the parameters of the burst assembly policy. Based on these results, we further develop an efficient adaptive burst assembly policy so as to optimize the throughput and delay performance of the burst-frame-based CSMA/CA protocol. Kejie Lu received the B.E. and M.E. degrees in Telecommunications Engineering from Beijing University of Posts and Telecommunications, Beijing, China, in 1994 and 1997, respectively. He received the Ph.D. degree in Electrical Engineering from the University of Texas at Dallas in 2003. In 2004 and 2005, he was a postdoctoral research associate in the Department of Electrical and Computer Engineering, University of Florida. Currently, he is an assistant professor in the Department of Electrical and Computer Engineering, University of Puerto Rico at Mayagüez. His research interests include architecture and protocols design for computer and communication networks, performance analysis, network security, and wireless communications. Jianfeng Wang received the B.E. and M.E. degrees in electrical engineering from Huazhong University of Science and Technology, China, in 1999 and 2002, respectively, and the Ph.D. degree in electrical engineering from University of Florida in 2006. From January 2006 to July 2006, he was a research intern in wireless standards and technology group, Intel Corporation. In October 2006, he joined Philips Research North America as a senior member research staff in wireless communications and networking department. He is engaged in research and standardization on wireless networks with emphasis on medium access control (MAC). Dapeng Wu received B.E. in Electrical Engineering from Huazhong University of Science and Technology, Wuhan, China, in 1990, M.E. in Electrical Engineering from Beijing University of Posts and Telecommunications, Beijing, China, in 1997, and Ph.D. in Electrical and Computer Engineering from Carnegie Mellon University, Pittsburgh, PA, in 2003. Since August 2003, he has been with Electrical and Computer Engineering Department at University of Florida, Gainesville, FL, as an Assistant Professor. His research interests are in the areas of networking, communications, multimedia, signal processing, and information and network security. He received the IEEE Circuits and Systems for Video Technology (CSVT) Transactions Best Paper Award for Year 2001, and the Best Paper Award in International Conference on Quality of Service in Heterogeneous Wired/Wireless Networks (QShine) 2006. Currently, he serves as the Editor-in-Chief of Journal of Advances in Multimedia, and an Associate Editor for IEEE Transactions on Wireless Communications, IEEE Transactions on Circuits and Systems for Video Technology, IEEE Transactions on Vehicular Technology, and International Journal of Ad Hoc and Ubiquitous Computing. He is also a guest-editor for IEEE Journal on Selected Areas in Communications (JSAC), Special Issue on Cross-layer Optimized Wireless Multimedia Communications. He served as Program Chair for IEEE/ACM First International Workshop on Broadband Wireless Services and Applications (BroadWISE 2004); and as a technical program committee member of over 30 conferences. He is Vice Chair of Mobile and wireless multimedia Interest Group (MobIG), Technical Committee on Multimedia Communications, IEEE Communications Society. He is a member of the Best Paper Award Committee, Technical Committee on Multimedia Communications, IEEE Communications Society. Yuguang Fang received a Ph.D. degree in Systems Engineering from Case Western Reserve University in January 1994 and a Ph.D. degree in Electrical Engineering from Boston University in May 1997. He was an assistant professor in the Department of Electrical and Computer Engineering at New Jersey Institute of Technology from July 1998 to May 2000. He then joined the Department of Electrical and Computer Engineering at University of Florida in May 2000 as an assistant professor and got an early promotion to an associate professor with tenure in August 2003 and to a full professor in August 2005. He has published over 200 papers in refereed professional journals and conferences. He received the National Science Foundation Faculty Early Career Award in 2001 and the Office of Naval Research Young Investigator Award in 2002. He has served on several editorial boards of technical journals including IEEE Transactions on Communications, IEEE Transactions on Wireless Communications, IEEE Transactions on Mobile Computing and ACM Wireless Networks. He have also been actively participating in professional conference organizations such as serving as The Steering Committee Co-Chair for QShine, the Technical Program Vice-Chair for IEEE INFOCOM’2005, Technical Program Symposium Co-Chair for IEEE Globecom’2004, and a member of Technical Program Committee for IEEE INFOCOM (1998, 2000, 2003–2007). He is a senior member of the IEEE.     

Proportional fair throughput allocation in multirate IEEE 802.11e wireless LANs

Under heterogeneous radio conditions, Wireless LAN stations may use different modulation schemes, leading to a heterogeneity of bit rates. In such a situation, 802.11 DCF allocates the same throughput to all stations independently of their transmitting bit rate; as a result, the channel is used by low bit rate stations most of the time, and efficiency is low. In this paper, we propose a more efficient throughput allocation criterion based on proportional fairness. We find out that, in a proportional fair allocation, the same share of channel time is given to high and low bit rate stations, and, as a result, high bit rate stations obtain more throughput. We propose two schemes of the upcoming 802.11e standard to achieve this allocation, and compare their delay and throughput performance. Albert Banchs received his M.Sc. and Ph.D. degrees in Telecommunications from the Technical University of Catalonia in 1997 and 2002, respectively. His Ph.D. received the national award for best thesis on Broadband Networks granted by the Professional Association of Telecommunication Engineers. He worked for the International Computer Science Institute, Berkeley, in 1997, for Telefonica I+D, Madrid, in 1998 and for NEC Network Laboratories, Heidelberg, from 1998 to 2003. Since 2003 he is with the University Carlos III of Madrid. Dr. Banchs is Associate Editor of IEEE Communications Letters and has been TPC member of several conferences and workshops including INFOCOM, ICC, GLOBECOM and QoS-IP. His current research interests include resource allocation, QoS and performance evaluation of wireless and wired networks. Pablo Serrano was born in Tarifa, Spain, on May 17, 1979. He received a M.Sc. degree in Telecommunications from the University Carlos III of Madrid in 2002. Since that date he is a Ph.D. candidate and a lecturer at the Telematics Department of the same university. His current research interests are performance evaluation and resource allocation of WLAN networks. Huw Edward Oliver received his MA degree in Mathematics at Cambridge University (1980), and his MSc (1985) and PhD (1988) in Computer Science at the University College of Wales, Aberystwyth. He joined Hewlett-Packard Laboratories, Bristol in 1989 to work on Software Development Environments. Following a period at HP’s Software Engineering Systems, Colorado in 1992 he returned to HP Labs in 1993 as Senior Member of Technical Staff and worked on real-time fault tolerant telecommunication systems. From 1997 to 2000 he was appointed Manager of Hewlett-Packard’s Internet Research Institute. He worked as Technical Director of the European MMAPPS Project from 2000 to 2002, as Senior Research Fellow at Lancaster University from 2002 to 2004, and as Visiting Professor at University Carlos III of Madrid from 2004 to 2005. Since 2005 he has been Senior Researcher with Ericsson R&D Ireland, Athlone where he is responsible for the next-generation network management architecture.     

Essential Considerations in Implementing the Smart Antenna System for Downlink Beamforming

This paper addresses some essential problems that have to be taken into consideration in implementing the smart antenna base station (SABS) for downlink beamforming. In order to provide proper downlink beamforming as well as uplink beamforming, a pragmatic procedure of automatic calibration is proposed. Through the experimental test, we confirm that the proposed calibration technique has eliminated the problem of the phase differences of the signal path associated with each antenna. Also, in this paper, we first analyze the multipath condition under which the auxiliary pilot becomes indispensable for detecting the data transmitted on the data channel and what happens if the auxiliary pilot is not available. Then, the performance of the downlink beamforming utilizing the auxiliary pilot is analyzed through the computer simulations. Finally, we present a comparison of downlink communications to uplink ones in terms of throughputs available at each of uplink and downlink communications. Weon-Cheol Lee received the B.S, M.S, and Ph.D. degree in Electronic Communication Engineering from Hanyang University, Korea, in 1992, 1994, 2005, respectively. From 1994 to 2000, he was with LG Electronic Inc., where he had worked for developing the digital VCR, digital cable modem, digital TV. Since 2001, he has been a professor with department of information and communications, Yong-in Songdam College, Korea. His research interests include smart antennas, mobile communications beyond the third generation, digital broadcasting technology, and communication signal processing. Dr. Lee also received the Best Research Paper Award and Excellent Research Engineer Award from LG Electronics, respectively. Seungwon Choireceived the BS degree from Hanyang University, Seoul, Korea, and the M.S. degree from Seoul National University, Korea, 1980 and 1982, respectively, both in electronics engineering, the MS degree (computer engineering) in 1985, and the PhD degree (electrical engineering), in 1988, both from Syracuse University, Syracuse, NY. From 1988 to 1989 he was with the Department of Electrical and Computer Engineering of Syracuse University, Syracuse, NY, as an Assistant Professor. In 1989 he joined the Electronics and Telecommunications Research Institute, Daejeon, Korea. From 1990 to 1992 he was with the Communications Research Laboratory, Tokyo, Japan, as a Science and Technology Agency fellow, developing the adaptive antenna array systems and adaptive equalizing filters. He joined Hanyang University, Seoul, Korea, in 1992 as an assistant professor. He is a professor in the School of Electrical and Computer Engineering of Hanyang University. Since 2003, Dr. Choi has been serving as a Vice Chairman and the representative of the ITU region 3 for SDR (Software Defined Radio) Forum and as a Director of the HY-SDR Research Center, MIC, Korea. His research interests include digital communications and adaptive signal processing with a recent focus on the implementation of the smart antenna systems for both mobile communication systems and wireless data systems. Jae-Moung Kim received the BS degree from Hanyang University, Korea in 1974, the MSEE degree from University of Southern California, USA in 1981, and the PhD degree from Yonsei University, Korea in 1987. He was a Vice President of Radio {&} Broadcasting Technology Laboratory and Director of Satellite Communication System Department at Electronics and Telecommunications Research Institute (ETRI) from September 1982 to March 2003. Since April of 2003, he has been a Professor in the Graduate School of Information Technology and Telecommunications, Inha University. He is a board member of directors of Korean Institute of Communication Science (KICS), a Vice President of Korea Society of Broadcast Engineers (KOSBE) and a senior member of IEEE. His research background is telecommunication systems modeling and performance analysis of broadband wireless access systems, mobile communications, satellite communications and broadcasting transmission technologies.     

Tightening the upper bound for the minimum energy broadcasting

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

Adaptive Chip-Level Channel Estimation for IMT-DS System: DL and UL

In this paper, chip-level adaptive channel estimation has been explored by using LMS algorithm for wideband CDMA channel estimation. The expression for the optimum step-size is modified for fading channel estimation problem. In addition, a new method is proposed to obtain channel estimates with known pilot symbols which is found to give better results than other methods. For slow fading channels, like pedestrian channel, LMS estimator with no update mode is found to give satisfactory results. For fast fading channels, like vehicular channel, a common decision directed technique of channel estimation is modified to be used at chip-level in the downlink (DL). A novel despreader-respreader based channel estimator has been proposed to obtain uplink channel estimates at chip level which resolves the deficiencies of conventional methods. The performance of Rake receiver with proposed channel estimation schemes for IMT-DS system – a 3G mobile communication standard – is evaluated in terms of BER. S. Faisal A. Shah received the B.S. degree from NED University of Engineering and Technology, Karachi, Pakistan, in 1998 and the M.S. degree from King Fahd University of Petroleum and Minerals, Dhahran, Saudi Arabia, in 2001, both in Electrical Engineering. From 2001 to 2004, he was a Lecturer in Electrical & Electronics Engineering Department, University of Sharjah, UAE. In September 2004, he joined the Electrical and Computer Engineering Department of University of Minnesota, USA, as a research assistant where he is currently pursuing the Ph.D. degree in Electrical Engineering. His research interests include ultra-wideband communication systems, adaptive signal processing and its application to wireless communication systems. Asrar U.H. Sheikh graduated from the University of Engineering and Technology, Lahore, Pakistan with first class honours and received his M.Sc. and Ph.D. degrees from the University of Birmingham, England, in 1966 and 1969 respectively. After completing teaching assignments in several countries, he returned to Birmingham as a Research Fellow in 1975. He worked at Carleton University from 1981 to 1997, first as Associate Professor and later as a Professor and Associate Chairman for Graduate Studies. He was the Founder Director of PCS Research Laboratory at Carleton University. Before taking position of Bugshan/Bell Lab Chair in Telecommunications at King Fahd University of Petroleum and Minerals in April 2000, he was a Professor and Associate Head of the Department of Electronic and Information Engineering at Hong Kong Polytechnic University, where he was founding director of Wireless Information Systems Research (WISR) Centre. At KFUPM he established Telecommunications Research Laboratory. Professor Sheikh is the author of a recently published book, Wireless Communications - Theory & Techniques published by Kluwer Academic Publishers, Orwell, Mass., USA. He has published over 230 papers in international journals and conference proceedings. He also authored or co-authored 30 technical reports. Dr. Sheikh is a co-recipient of Paul Adorian Premium from IERE (London) for his work on impulsive noise characterization. He was awarded teaching achievement awards in 1984 and 1986, and Research Achievement Award in 1994, all by Carleton University. Dr. Sheikh is actively involved in several international conferences mainly as a member of Technical Program Committees. He has organized and chaired many technical sessions at several international conferences. He Chaired the Technical Program of VTC'98. He is an editor of IEEE Transaction on Wireless Communications, a Technical Associate Editor of IEEE Communication Magazine. He is on the Editorial Board of Wireless Personal Communications, and Wireless Communications and Mobile Computing. He was a co-guest editor of the Special Issue of WPC on Interference. Dr. Sheikh is also on the reviewer panels of many IEEE and IEE Transactions and Journals. Dr. Sheikh has been consultant to many private companies and government agencies. His current interests are in signal processing in communications, mitigation of interference, spread spectrum and 3G and beyond systems. His other interests include helping developing countries in education and research. He had assignments under UNDP's sustained Development Program. He is a Fellow of the IEEE and a Fellow of the IEE. Dr. Sheikh is listed in Marquis Who's Whos in the world and Who's Who in Science and Engineering.     

QoS Aware Multi-Channel Scheduling for IEEE 802.15.3 Networks

From a multimedia applications perspective, there is an ever increasing demand for wireless devices with higher bandwidth to support high data rate flows. One possible solution to support the demand for higher bandwidth is to utilize the full spectrum by simultaneously using multiple channels for transmission. Recent approval by the Federal Communications Commission (FCC) has led to considerable interest in exploiting Ultra Wideband (UWB) access on an unlicensed basis in the 3.1--10.6 GHz band. Currently, the IEEE TG802.15.3a standards group is in the process of developing an alternative high-speed link layer design conformable with the IEEE 802.15.3 Wireless Personal Area Network (WPAN) multiple access (MAC) protocol. One of the proposals, based on the concept of Orthogonal Frequency Division Multiplexing (OFDM), divides the spectrum into multiple bands and achieves channelization through the use of different time-frequency codes. These multiple channels can help satisfy the increasing demand for higher bandwidth in order to support high data rate multimedia applications. In this paper, we present a QoS-aware, multi-channel scheduling algorithm that simultaneously utilizes the various channels available in the UWB network. Aniruddha Rangnekar is a doctoral student in the Department of Computer Science and Electrical Engineering at the University of Maryland, Baltimore County. He received the B.E. degree in Computer Engineering from the University of Pune, India in 1998 and a M.S. in Computer Science from the University of Maryland, Baltimore County in 2001. From January 2002 to date, he has been involved in graduate research in University of Maryland, Baltimore County. During the summer of 2004, he worked as the MAC development engineer at Staccato Communications, San Diego, CA. His current interests are in the areas of wireless ad hoc networks, multicast routing protocols, ultra wideband communications and MAC protocol development. He is a member of the MACSim group of the Multiband OFDM alliance (MBOA). Krishna M. Sivalingam is an Associate Professor in the Dept. of CSEE at University of Maryland, Baltimore County. Previously, he was with the School of EECS at Washington State University, Pullman from 1997 until 2002; and with the University of North Carolina Greensboro from 1994 until 1997. He has also conducted research at Lucent Technologies' Bell Labs in Murray Hill, NJ, and at AT&T Labs in Whippany, NJ. He received his Ph.D. and M.S. degrees in Computer Science from State University of New York at Buffalo in 1994 and 1990 respectively; and his B.E. degree in Computer Science and Engineering in 1988 from Anna University, Chennai (Madras), India. While at SUNY Buffalo, he was a Presidential Fellow from 1988 to 1991. His research interests include wireless networks, optical wavelength division multiplexed networks, and performance evaluation. He holds three patents in wireless networks and has published several research articles including more than thirty journal publications. He has published an edited book on Wireless Sensor Networks in 2004 and edited books on optical WDM networks in 2000 and 2004. He served as a Guest Co-Editor for special issues of the ACM MONET journal on “Wireless Sensor Networks” in 2003 and 2004; and an issue of the IEEE Journal on Selected Areas in Communications on optical WDM networks (2000). He is co-recipient of the Best Paper Award at the IEEE International Conference on Networks 2000 held in Singapore. His work has been supported by several sources including AFOSR, NSF, Cisco, Intel and Laboratory for Telecommunication Sciences. He is a member of the Editorial Board for ACM Wireless Networks Journal, IEEE Transactions on Mobile Computing, Ad Hoc and Sensor Wireless Networks Journal, and KICS Journal of Computer Networks. He serves as Steering Committee Co-Chair for the International Conference on Broadband Networks (BroadNets) that was created in 2004. He is currently serving as General Co-Vice-Chair for the Second Annual International Mobiquitous conference to be held in San Diego in 2005 and as General Co-Chair for the First International Conference on Security and Privacy for Emerging Areas in Communication Networks to be held in Athens, Greece in Sep. 2005. He served as Technical Program Co-Chair for the First IEEE Conference on Sensor and Ad Hoc Communications and Networks (SECON) held at Santa Clara, CA in 2004; as General Co-Chair for SPIE Opticomm 2003 (Dallas, TX) and for ACM Intl. Workshop on Wireless Sensor Networks and Applications (WSNA) 2003 held in conjunction with ACM MobiCom 2003 at San Diego, CA; as Technical Program Co-Chair of SPIE/IEEE/ACM OptiComm conference at Boston, MA in July 2002; and as Workshop Co-Chair for WSNA 2002 held in conjunction with ACM MobiCom 2002 at Atlanta, GA in Sep 2002. He is a Senior Member of IEEE and a member of ACM.     

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”.     

Multipath Mitigation Technique Based on Partial Autocorrelation Function

GPS positioning accuracy in indoor and urban canyons environments is greatly affected by multipaths due to distortions in its autocorrelation function. In this paper, the first sidelobe of Pseudorandom Noise (PN) code autocorrelation is studied and a new multipath mitigation technique based on PN code autocorrelation function is presented. This new technique relies on the detection of the partial autocorrelation function that is affected by multipath signals. The increase in fractional delay of the line-of-sight (LOS) signal is calculated. Simulation results indicate that the proposed technique has superior performance compared with the 0.1-chip-spacing narrow correlator on mitigating multipath signals, especially the short-delay multipath signals. Zhang Zhen obtained his Bachelor’s Degree from Beijing Information and Technology Institute in 1999, Master’s Degree from Tsinghua University, Beijing China, in 2002. He now is a Ph.D. student in Nanyang Technological University. Currently he also works as a Research Associate in the Positioning and Wireless Technology Center (PWTC), NTU. His research interest includes multipath mitigation for GPS, software GPS receiver design, indoor GPS as well as Ultra Wide Band (UWB) based ranging systems. C. L. Law is an Associate Professor in School of EEE, NTU and the Director of PWTC. Dr. Law’s current research area is in Wireless Networks. His research topics are in microwave integrated circuits, indoor wireless channel modeling, analysis of indoor wireless LAN performances and in techniques for overcoming the time-dispersion distortions in high speed wireless LAN. E. Gunawan is an Associate Professor in School of EEE, NTU and his research interest includes Error Correction Codings, Modeling of Cellular Communications Systems, Power Control for CDMA Cellular Systems, MAC Protocols, Multicarrier Modulations, Multiuser Detections, Space-time Coding, Radio-location Systems, UWB and its applications for Human Body Vital Signs Detection, and Powerline Communications.     

Effective Capacity-Based Quality of Service Measures for Wireless Networks

An important objective of next-generation wireless networks is to provide quality of service (QoS) guarantees. This requires a simple and efficient wireless channel model that can easily translate into connection-level QoS measures such as data rate, delay and delay-violation probability. To achieve this, in Wu and Negi (IEEE Trans. on Wireless Communications 2(4) (2003) 630–643), we developed a link-layer channel model termed effective capacity, for the setting of a single hop, constant-bit-rate arrivals, fluid traffic, and wireless channels with negligible propagation delay. In this paper, we apply the effective capacity technique to deriving QoS measures for more general situations, namely, (1) networks with multiple wireless links, (2) variable-bit-rate sources, (3) packetized traffic, and (4) wireless channels with non-negligible propagation delay. Dapeng Wu received B.E. in Electrical Engineering from Huazhong University of Science and Technology, Wuhan, China, in 1990, M.E. in Electrical Engineering from Beijing University of Posts and Telecommunications, Beijing, China, in 1997, and Ph.D. in Electrical and Computer Engineering from Carnegie Mellon University, Pittsburgh, PA, in 2003. From July 1997 to December 1999, he conducted graduate research at Polytechnic University, Brooklyn, New York. During the summers of 1998, 1999 and 2000, he conducted research at Fujitsu Laboratories of America, Sunnyvale, California, on architectures and traffic management algorithms in the Internet and wireless networks for multimedia applications. Since August 2003, he has been with Electrical and Computer Engineering Department at University of Florida, Gainesville, FL, as an Assistant Professor. His research interests are in the areas of networking, communications, multimedia, signal processing, and information and network security. He received the IEEE Circuits and Systems for Video Technology (CSVT) Transactions Best Paper Award for Year 2001. Currently, he is an Associate Editor for the IEEE Transactions on Vehicular Technology and Associate Editor for International Journal of Ad Hoc and Ubiquitous Computing. He served as Program Chair for IEEE/ACM First International Workshop on Broadband Wireless Services and Applications (BroadWISE 2004); and as TPC member of over 20 conferences such as IEEE INFOCOM'05, IEEE ICC'05, IEEE WCNC'05, and IEEE Globecom'04. He is Vice Chair of Mobile and wireless multimedia Interest Group (MobIG), Technical Committee on Multimedia Communications, IEEE Communications Society. He is a member of the Award Committee, Technical Committee on Multimedia Communications, IEEE Communications Society. He is also Director of Communications, IEEE Gainesville Section. Rohit Negi received the B.Tech. degree in Electrical Engineering from the Indian Institute of Technology, Bombay, India in 1995. He received the M.S. and Ph.D. degrees from Stanford University, CA, USA, in 1996 and 2000 respectively, both in Electrical Engineering. He has received the President of India Gold medal in 1995. Since 2000, he has been with the Electrical and Computer Engineering department at Carnegie Mellon University, Pittsburgh, PA, USA, where he is an Assistant Professor. His research interests include signal processing, coding for communications systems, information theory, networking, cross-layer optimization and sensor networks.     

Block-Orthogonal Frequency Division Multiplexing in Multi-Path Fading Channel

Orthogonal frequency division multiplexing (OFDM) is robust against multi-path interference due to using a lot of low symbol rate sub-carriers. In order to mitigate the degradation due to multi-path interference, guard time interval (GI) is inserted into each OFDM symbol. However, redundant allocation to GI leads to loss of effective transmission power. We propose the Block-OFDM which can reduce the GI overhead ratio per frame compared with conventional OFDM. In Block-OFDM system frequency domain equalization (FDE) is carried out in order to remove multi-path interference. We evaluated Block-OFDM performance in a frequency selective fading channel and compared with that of conventional OFDM. Ryohei Kimura received his B.E. and M.S degrees in communications engineering form Tohoku University, Sendai, Japan, in 2001 and 2003, respectively. In 2003, he joined Panasonic Mobile Communications Co., Ltd. His current research interests include such mobile communication technologies as OFDM and MIMO (MLD), and the like. Akiyoshi Monma received his B.E. in communications engineering form Tohoku University, Sendai, Japan, in 1998. In 1998, he joined Panasonic Mobile Communications Sendai R&D Lab. Co., Ltd. His current research interests include such mobile communication technologies as OFDM and PAPR reduction, and the like. Jinsong Duan received his B.E. and M.S. from Changsha Institute of Technology, China in 1987 and 1990. He received his Ph.D. from Osaka City University, Japan in 2000. From 2000–2003 he was with Mitsubishi Electric Corporation, where he engaged in research and development of WCDMA systems. From 2003, he joined Panasonic Mobile Communications Co., Ltd. His current interests include such mobile communication technologies as OFDM, MIMO, link adaptation, scheduling, and TDMA/FDMA/CDMA systems. Mitsuru Uesugi received his B.E. degree from Waseda University in 1986 and received his Ph.D degree from Tohoku University in 2004, respectively. He is a general manager in the Mobile Communication Technology Development Center of Panasonic Mobile Communications Co., Ltd. His current research interests include such mobile communication technologies as equalization, interference cancellation, modulation method, and the like.     

The Development of Intelligent Beamforming Antenna Systems for Stratospheric Platforms in the Millimeter-Wave Band

In this paper, we describe intelligent beamforming antenna systems that can be used in the millimeter-wave band for High-altitude platform systems. We have developed two antenna systems for the millimeter-wave band and have designed experiments to test the efficiency of the developed systems. One is a multi-beam-horn antenna that enables high-speed transmission, and the other is an array antenna that digitally controls antenna beams. These antenna systems are also designed to work in the stratosphere. We also describe our solutions to the problems of low temperature and low pressure and show that the two antenna systems can function well in the stratosphere through tests conducted on the ground.On April 1, 2004, the Communications Research Laboratory (CRL) and the Telecommunications Advancement Organization of Japan (TAO) merged to create NICT.Hiroyuki Tsuji received the B.S., M.S., and Ph.D. degrees from Keio University in 1987, 1989, and 1992, respectively. Since 1992, he has been working in the Communications Research Laboratory, Independent Administrative Institution, Japan. In 1999, he was a visiting researcher at University of Minnesota. He is now a senior researcher of Wireless Innovation Systems Group in the Yokosuka Radio Communications Research Center of NICT (National Institute on Information and Communications Technology, reorganized from CRL in April 2004). His research interests are in array signal processing, particularly as applied to communications. He received the IEICE 1996 Young Engineer Award. He is a member of IEICE and IEEE.Masayuki Oodo was born in Osaka, Japan, on February 1, 1969. He received B.E., M.E. and D.E. degrees in Electrical and Electronic Engineering from Tokyo Institute of Technology, Tokyo, Japan in 1992, 1994 and 1997, respectively. In 1997, he joined the Communications Research Laboratory (CRL, now part of the National Institute of Information and Communications Technology, or NICT), where he has been researching array antennas for wireless communication and frequency-sharing issues between HAPS and other systems. Dr. Oodo received the Paper Presentation Award from IEICE Japan in 1995, the Young Scientist Award from URSI in 1996, the Young Engineer Award from IEICE Japan in 1997, and the Young Engineer Award from IEEE AP-S, Tokyo Chapter in 1998. He is a member of IEEE.Ryu Miura received the B.E., M.E., and PhD degrees in Electrical Engineering from Yokohama National University, Yokohama, Japan, in 1982, 1984, and 2000, respectively. He joined Communications Research Lab (CRL), Ministry of Posts and Telecommunications, Tokyo, Japan in 1984, where he worked for research on mobile satellite communication systems using the Engineering Test Satellite, ETS-V. During 1991–1992, he was a visiting researcher in AUSSAT, Pty. Ltd. (now Optus, Pty. Ltd.), Sydney, Australia. During 1993–1996, he was a senior researcher in ATR Optical and Radio Communications Research Labs, Kyoto, Japan, where he worked for research on digital beamforming antennas for mobile communications. He is now a group leader of Wireless Innovation Systems Group in the Yokosuka Radio Communications Research Center of NICT (National Institute on Information and Communications Technology, reorganized from CRL in April 2004), where he works for R&D on wireless communication systems using stratospheric platforms. Dr. Miura is a member of IEEE and IEICE.Mikio Suzuki received a B.S. degree in electronic engineering from Keio University in 1970. He joined Mitsubishi Electric Corporation in 1970, where he researched and developed microwave integrated circuits and waveguide array antennas for defense radars and missiles. He is now at the NICT Yokosuka Stratospheric Platform Research Center, and his current research interests lie in the system design of applications for wireless communication systems using a stratospheric platform and the development of related communication equipment. He is a member of the IEICE of Japan.