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).     

Reduced-Complexity Iterative Multiuser Detection for DS-CDMA

A reduced-complexity iterative multiuser detection scheme is proposed. The scheme involves a simple way of choosing only K + 1 user bit vectors instead of the full-complexity 2^K for the likelihood computation, thus reducing the complexity to O(K). An alternative, reduced computation method of increasing this list of vectors after each iteration is also presented. Simulations over AWGN, imperfect power control and multipath conditions demonstrate that the performance of the proposed reduced-complexity method is close to that of the full-complexity.Ju Yan Pan received the B.S.E.E. degree from Mississippi State University, U.S.A., in 1998 and the M.Eng. degree from Nanyang Technological University, Singapore, in 2002. He is currently working as a system design engineer at the wireless communication technology department of Oki Techno Centre Pte. Ltd. in Singapore Science Park II. His current reserach interests include third-generation WCDMA systems, turbo decoding and multiuser detection.Cheong Boon Soh received the Bachelor of Engineering in Electrical and Computer Systems Engineering (Hons I) and Ph.D. degrees from Monash University, Victoria, Australia, in 1983 and 1987, respectively. He is an Associate Professor in the School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore. He has published more than one hundred international journal papers. His current research interests are robust control, system theory, nonlinear systems, coding theory, mobile communication systems and intelligent systems.Gunawan Erry received his B.Sc degree in Electrical and Electronic Engineering from the University of Leeds, U.K., in 1983. He then received his MBA and Ph.D. in total technology from Bradford University in 1984 and 1988 respectively. From 1984 to 1988, he worked for Communication Systems Research Ltd, U.K. as a satellite communication systems engineer. In 1988, he moved to Space Communications (SAT-TEL) Ltd, U.K. He joined the School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore in 1989. Currently, he is an Associate Professor in the School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore. His current research interests are in digital communications, mobile and satellite communications, error coding and spread-spectrum. He has published over sixty international research papers and has been a consultant to a local company on the study of DECT system and Bluetooth.     

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.     

Turbo Decoding of Super-Orthogonal Space-Time Trellis Codes in Rayleigh Fading Channels

Space-time trellis codes have shown to provide a good performance in Rayleigh fading channels. Recently Super-orthogonal space-time trellis codes have shown to outperform these codes, and also provide a systematic design method to maximize diversity and coding gain in quasi-static Rayleigh fading channels. We investigate the performance of these new codes in rapid Rayleigh fading channels and further propose two concatenated versions of these codes. We further investigate the effect of imperfect channel state information on one of the concatenated versions. Some simulation results of the various concatenated schemes in quasi-static and rapid Rayleigh fading channels are presented. Jayesh N. Pillai received the B.Tech degree in Electrical and Electronic Engineering from the University of Calicut, Kerala, India in 2001. He is currently pursuing an MScEng degree in Electronic Engineering at the School of Electrical, Electronic and Computer Engineering at the University of KwaZulu-Natal, Durban, South Africa. His research interests are in the area of wireless communications, including multiple-antenna systems, space-time coding and channel coding. Stanley Henry Mneney obtained his B.Sc.(Hons) Eng. Degree from the University of Science and Technology, Kumasi in Ghana in 1976. In 1979 he completed his M.A.Sc. from the University of Toronto in Canada. In a Nuffic funded project by the Netherlands government he embarked on a sandwich Ph.D. programme between the Eindhoven Univesity of Technology and the University of Dar es Salaam, the latter awarding the degree in 1988. His co-supervisors were Prof Jens Arnbak and Prof Ramje Prasad representing the two Universities. The research area was on the application satellite technology to provide low cost systems and services to the rural population in the developing countries.Prof Mneney has taught at the Universities of Dar es Salaam, Nairobi, Durban Westville and he is currently an Associate Professor and Deputy Head of School of Electrical, Electronic and Computer Engineering at the University of KwaZulu-Natal in South Africa. His research interest includes Signal and Image processing, radio propagation and communication systems.     

MIMO Channel Characterization for Short Range Fixed Wireless Propagation Environments

This paper reports results from wideband MIMO measurements performed in short range fixed wireless environments at 5.2 GHz. The objective is to provide MIMO channel characterization results for the measured environments and contribute to the limited available similar studies. Two kinds of propagation scenarios are investigated, rooftop to rooftop and street to rooftop, at three different sites always under LOS propagation conditions. The analysis of measurement data is performed in the context of non physical modeling, providing insight into the statistics of the measured channels. In particular, the slow time varying nature of the channel is studied and the narrow Doppler spectrum shape is approximated. Furthermore, frequency correlation results are obtained and the typical delay dispersion measures are extracted. Then, the antenna correlation is studied and the error of the Kronecker product approximation is evaluated. Finally, capacity results are provided and the channel measurements are characterized in terms of spatial multiplexing quality and multipath richness through condition number analysis. Nikolaos D. Skentos received his Diploma in Electrical and Computer Engineering from the National Technical University of Athens (NTUA), Greece in October 2000. Since January 2001 he has been a research associate at the Mobile Radio Communications Laboratory at the NTUA, and he is currently working towards the Ph.D. degree. His research interests include channel measurements, MIMO channel characterization, MIMO algorithms and space time processing. He has been active in the IST STINGRAY project, the COST 273 Action and the ACE Network of Excellence. He is also a member of the National Technical Chamber of Greece since 2001. Athanasios G. Kanatas received the Diploma in Electrical Engineering from the National Technical University of Athens, Greece, in 1991, the M.Sc. degree in Satellite Communication Engineering from the University of Surrey, Surrey, UK in 1992, and the Ph.D. degree in Mobile Satellite Communications from the National Technical University of Athens, Greece in February 1997. From 1993 to 1994 he was with National Documentation Center of National Research Institute. In 1995 he joined SPACETEC Ltd. where he was Technical Project Manager for VISA/EMEA VSAT Project in Greece. In 1996 he joined the Mobile Radio Communications Laboratory as a research associate. From 1999 to 2002 he was with the Institute of Communication & Computer Systems. In 2000 he became a member of the Board of Directors of OTESAT S.A. He is an Assistant Professor in the Department of Technology Education and Digital Systems at University of Piraeus. His current research interests include channel characterization and estimation, simulation and modeling for mobile, mobile satellite, and future wireless communication systems. He has been a Senior Member of IEEE since 2002, and is also a member of the Technical Chamber of Greece. In 1999 he was elected Chairman of the Communications Society of the Greek IEEE Section. Panagiotis I. Dallas was born 1967 in Thessaloniki, Greece. He obtained his diploma and Ph.D. degree from the Electrical and Computer Engineering Department of Aristotle University of Thessaloniki, Greece, in 1990 and 1997, respectively. Since 1998 he joined with INTRACOM where he currently is Section Manager of Advanced Communications Technologies branch of Emerging Technologies & Markets department, leading the next generation of broadband wireless access systems for internal and EU projects. He runs the relevant standardization activities (IEEE 802.16 and ETSI/BRAN HIPERMAN) in INTRACOM and he represents the company in WiMAX forum. Finally, he has over 30 publications in international journals and conferences. Philip Constantinou received the Diploma in Physics from the National University of Athens in 1972, the Master of Applied Science in Electrical Engineering from the University of Ottawa, Ontario, Canada in 1976, and the Ph.D. degree in Electrical Engineering in 1983 from Carleton University, Ottawa, Ontario, Canada. From 1976 to 1979 he was with Telesat Canada as a Communications System Engineer. In 1980 he joined the Ministry of Communications in Ottawa, Canada where he was engaged in the area of Mobile Communication. From 1984 to 1989 he was with the National Research Center Demokritos in Athens, Greece where he was involved in several research projects in the area of Mobile Communications. In 1989 he joined the National Technical University of Athens where he is currently a Professor and Director of the Mobile Radio Communications Laboratory. His current research interests include Personal Communications, Mobile Satellite Communications, and Interference Problems on Digital Communications Systems.     

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.     

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).     

Interference Mitigation on WLANs Using Smart Antennas

This paper investigates the performance of a fixed Wireless LAN in which nodes are equipped with fully adaptive smart antennas. The considered smart antenna system is a uniform circular array of microstrip patch elements in which the weights are updated using the unconstrained LMS algorithm. The behavior of a new directional MAC protocol for spatial multiplexing is analyzed and compared with IEEE 802.11 DCF. The paper purpose is the evaluation of interference and multipath effects on SDMA, using realistic models for the channel and for the smart antenna system. The link model takes into account path loss, cochannel interference and multipath, using a modified Jakes model. Results show that the performance of the WLAN are strictly dependent on the interferer characteristics and on the angular spread of the channel. Fulvio Babich was born in Trieste, Italy. He received the doctoral degree in electrical engineering, from the University of Trieste, in 1984. From 1984 to 1987 he was with the Research and Development Department of Telettra (Vimercate), working on optical communications. From 1987 to 1992 he was with Research and Development Department of Zanussi (Zeltron), where he held the position of Company Head in the Home System European projects. In 1992, he joined the Department of Electrical Engineering (DEEI) of the University of Trieste, where he is associate professor of digital communications. His current research interests are in the field of wireless networks and personal communications. Massimiliano Comisso was born in Trieste, Italy. He received the degree of “Laurea" in Electronic Engineering from the University of Trieste. Currently, he is a PhD student at the Department of Electrical Engineering (DEEI) at University of Trieste in information technology. His research interests include wireless networks, adaptive arrays and small antennas. Marco D'Orlando was born in Tolmezzo, Italy, in September 1978. He received the Electronic Engineering degree (summa cum laude) from the University of Trieste, Italy, in December 2003. He is currently working toward the Ph.D. degree in the Department of Electrical and Electronic Engineering (DEEI) at University of Trieste. His research interests are in the field of multimedia communications, networking, joint source channel coding and resource allocation. Lucio Manià was born in Ronchi dei Legionari, Italy, in 1942. He received the Electronic Engineering degree from the University of Trieste, Italy, in 1968. Since 1970 he has been an Assistant Professor with the Department of Electrical and Electronic Engineering, where he is currently an Associate Professor. From 1975 to 1985 he was a consulting engineer with Co.El. S.p.A., where he was involved in antenna design for FM and TV broadcasting systems. His current scientific interests include electromagnetic compatibility for safety purposes, wireless communications and numerical techniques for electromagnetic simulations.     

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.     

Blind Stochastic Feature Transformation for Channel Robust Speaker Verification

To improve the reliability of telephone-based speaker verification systems, channel compensation is indispensable. However, it is also important to ensure that the channel compensation algorithms in these systems surpress channel variations and enhance interspeaker distinction. This paper addresses this problem by a blind feature-based transformation approach in which the transformation parameters are determined online without any a priori knowledge of channel characteristics. Specifically, a composite statistical model formed by the fusion of a speaker model and a background model is used to represent the characteristics of enrollment speech. Based on the difference between the claimant's speech and the composite model, a stochastic matching type of approach is proposed to transform the claimant's speech to a region close to the enrollment speech. Therefore, the algorithm can estimate the transformation online without the necessity of detecting the handset types. Experimental results based on the 2001 NIST evaluation set show that the proposed transformation approach achieves significant improvement in both equal error rate and minimum detection cost as compared to cepstral mean subtraction and Znorm. Kwok-Kwong Yiu received a BEng (Hons) degree in 1992 and an MPhil degree in 2000 from the Department of Electronic and Information Engineering, The Hong Kong Polytechnic University. He was a Research Associate at the same institute from 2000 to 2001. He is currently a PhD student and his supervisor is Dr. M.W. Mak. His research interests include speaker verification, neural networks, and channel compensation. Man-Wai Makreceived a BEng (Hons) degree in Electronic Engineering from Newcastle Upon Tyne Polytechnic in 1989 and a PhD degree in Electronic Engineering from the University of Northumbria at Newcastle in 1993. He was a Research Assistant at the University of Northmubria at Newcastle, from 1990 to 1993. He joined the Department of Electronic Engineering at the Hong Kong Polytechnic University as a Lecturer in 1993 and as an Assistant Professor in 1995. Since 1995, Dr. Mak has been an executive committee member of the IEEE Hong Kong Section Computer Chapter. He is currently the chairman of the IEEE Hong Kong Section Computer Chapter. Dr. Mak's research interests include speaker recognition and neural networks. Ming-Cheung Cheung received a BSc (Hons) degree in Information Technology from The Hong Kong Polytechnic University in 2002. Since November 2002, he has been an MPhil student at the Department of Electronic and Information Engineering of The Hong Kong Polytechnic University. His research interests include pattern recognition, neural networks, and fusion techniques for multimodal biometric authentication. Sun-Yuan Kung received his Ph.D. Degree in Electrical Engineering from Stanford University. In 1974, he was an Associate Engineer of Amdahl Corporation, Sunnyvale, CA. From 1977 to 1987, he was a Professor of Electrical Engineering-Systems, the University of Southern California. Since 1987, he has been a Professor of Electrical Engineering, Princeton University. Since 1990, he has served as an Editor-In-Chief of Journal of VLSI Signal Processing Systems. He served as a founding member and General Chairman of various international conferences, including IEEE Workshops on VLSI Signal Processing in 1982 and 1986 (L.A.), International Conference on Application Specific Array Processors in 1990 (Princeton) and 1991 (Barcelona), and IEEE Workshops on Neural Networks and Signal Processing in 1991 (Princeton), 1992 (Copenhagen) and 1998 (Cambridge, UK), the First IEEE Workshops on Multimedia Signal Processing in 1997 (Princeton), and International Computer Symposium in 1998 (Tainan).Dr. Kung is a Fellow of IEEE. He was the recipient of 1992 IEEE Signal Processing Society's Technical Achievement Award for his contributions on “parallel processing and neural network algorithms for signal processing”. He was appointed as an IEEE-SP Distinguished Lecturer in 1994. He received 1996 IEEE Signal Processing Society's Best Paper Award. He was a recipient of the IEEE Third Millennium Medal in 2000. He has authored more than 300 technical publications, including three books “VLSI Array Processors”, (Prentice Hall, 1988) (with Russian and Chinese translations), “Digital Neural Networks”, Prentice Hall, 1993, and “Principal Component Neural Networks”, John Wiley, 1996.     

A Review of Audio Fingerprinting

An audio fingerprint is a compact content-based signature that summarizes an audio recording. Audio Fingerprinting technologies have attracted attention since they allow the identification of audio independently of its format and without the need of meta-data or watermark embedding. Other uses of fingerprinting include: integrity verification, watermark support and content-based audio retrieval. The different approaches to fingerprinting have been described with different rationales and terminology: Pattern matching, Multimedia (Music) Information Retrieval or Cryptography (Robust Hashing). In this paper, we review different techniques describing its functional blocks as parts of a common, unified framework. Pedro Cano received a B.Sc and M. Sc. Degree in Electrical Engineering from the Universitat Politècnica de Catalunya in 1999. In 1997, he joined the Music Technology Group of the Universitat Pompeu Fabra where he is currently pursuing his Ph.D. on Content-based Audio Identification. He has been assistant professor in the Department of Technologies of the Universitat Pompeu Fabra since 1999. His research interests and recent work include: signal processing for music applications, within a real-time voice morphing system for karaoke applications, pattern matching and information retrieval, specifically content-based audio identification. Eloi Batlle received his M.S. degree in electronic engineering in 1995 from the Politechnical University of Catalunya in Barcelona, Spain. He then joined the Signal Processing Group at the same university where he was working on robust speech recognition. He received a PhD on this subject in 1999. While he was a PhD student he also worked as a researcher at the Telecom Italia Lab during 1997. In 2000 he joined the Audiovisual Institute (a part of the Pompeu Fabra University). Currently he is a member of the Music Technology Group of the same Institute where he leads several reseach projects on music identification and similarity. In 2000 he also joined the Department of Technologies of the Pompeu Fabra University and he teaches several subjects to undergraduate and graduate students. From 2001 he is the Deputy Director of this Department. His research interests include information theory, music similary, statistical signal processing and pattern recognition. Ton Kalker was born in The Netherlands in 1956. He received his M.S. degree in mathematics in 1979 from the University of Leiden, The Netherlands. From 1979 until 1983, while he was a Ph.D. candidate, he worked as a Research Assistant at the University of Leiden. From 1983 until December 1985 he worked as a lecturer at the Computer Science Department of the Technical University of Delft. In January 1986 he received his Ph.D. degree in Mathematics. In December 1985 he joined the Philips Research Laboratories Eindhoven. Until January 1990 he worked in the field of Computer Aided Design. He specialized in (semi) automatic tools for system verification. Currently he is a member of the Processing and Architectures for Content MANagement group (PACMAN) of Philips Research, where he is working on security of multimedia content, with an emphasis on watermarking and fingerprinting for video and audio. In November 1999 he became a part-time professor in the Signal Processing Systems group of Jan Bergmans in the area of ‘signal processing methods for data protection’. He is a Fellow of the IEEE for his contributions to practical applications of watermarking, in particular watermarking for DVD-Video copy protection. His other research interests include wavelets, multirate signal processing, motion estimation, psycho physics, digital video compression and medical image processing. Jaap Haitsma was born in 1974 in Easterein, the Netherlands. He received his B.Sc. in Electronic Engineering from the Noordelijke Hogeschool Leeuwarden in 1997. He did his thesis in 1997 at the Philips Research Laboratories in Redhill, England, on the topic of: “Colour Management for Liquid Crystal Displays”. Currently he is with the Philips Research Laboratories, Eindhoven, the Netherlands, where he has been doing research into digital watermarking and fingerprinting of audio and video since late 1997. From 1999 to 2002 he was also a part-time student at the Technical University of Eindhoven, where he obtained his M.Sc. in Electronic Engineering. His areas of interest include digital signal processing, database search algorithms and software engineering.     

Adaptive Coding and Modulation for Mobile Wireless Access Via High Altitude Platforms

In this paper we are concerned with broadband wireless access via high altitude platform system, providing the Internet access and broadband multimedia services to passengers equipped with WLAN terminals connecting through a collective terminal mounted on the train. The main challenge in such scenario is the development of efficient and reliable radio interface for the broadband communication link in the mobile wireless access segment. We are focusing on performance analysis of the adaptive coding and modulation scheme in the communication link between a high altitude platform and a collective terminal on-board moving train. In order to increase the reliability of the communication system in a fading environment we also exploit space and platform diversity. The proposed approach significantly increases the throughput of the wireless access system, while bit error rate remains below the target value regardless of the considered propagation environment.Tomaz Javornik received his B.Sc., M.Sc. and Ph.D. degrees in electrical engineering from the University of Ljubljana, Slovenia, in 1987, 1990 and 1993, respectively. He joined the Jozef Stefan Institute in 1987, where he currently works as a researcher in the Department of Digital Communications and Networks. He is involved in the study of digital radio-relay systems, modulation techniques, coding, adaptive signal processing and digital mobile communication systems.Mihael Mohorcic received B.Sc., M.Sc. and Ph.D. degrees in Electrical Engineering from the University of Ljubljana, Slovenia, in 1994, 1998 and 2002, respectively, and M.Phil. degree in Electrical Engineering from University of Bradford, UK, in 1998. He is a research fellow in the Department of Digital Communications and Networks at the Jozef Stefan Institute. In 1996/1997 he spent 12 months as a Visiting Scientist at University of Bradford, Bradford, UK. His research interests include development and performance evaluation of network protocols and architectures for mobile and wireless communication systems, and resource management in satellite and high altitude platforms networks with the emphasis on routing algorithms and traffic engineering. He is a member of IEEE.Ales Svigelj received his B.Sc., M.Sc. and Ph.D. degrees in Electrical Engineering from the University of Ljubljana, Ljubljana, Slovenia, in 1997, 2000 and 2003 respectively. He is a research associate in the Department of Digital Communications and Networks at the Jozef Stefan Institute. In 2000/2001 he spent one year as a visiting researcher at Leeds Metropolitan University in Leeds, UK. He has participated in several national and international projects. His research interests concern the development of telecommunications systems, network protocols and architectures for satellite, high altitude platforms and terrestrial mobile communication systems. In 2004 he was awarded with The Jozef Stefan Golden Emblem Prize for outstanding contributions made to science in Doctoral theses in the field of natural sciences in Slovenia.Igor Ozimek received his B.Sc., M.Sc. and Ph.D. degrees in electrical engineering from the University of Ljubljana, Slovenia in 1980, 1988 and 1993, respectively. Since 1980 he has been with the Jozef Stefan Institute, Ljubljana, where he works as a researcher. His current interests include digital communications,DSP processing and computer networks.Gorazd Kandus received B.Sc., M.Sc. and Ph.D. degrees in Electrical Engineering from the University of Ljubljana, Ljubljana, Slovenia, in 1971, 1974 and 1991, respectively. He is currently the head of the Department of Digital Communications and Networks at the Jozef Stefan Institute and a Professor at the Faculty of Electrical Engineering, Computer Science and Information Technology, University of Maribor. He spent one year at Worchester Polytechnic Institute, Worchester, MA, as a Fulbright Fellow and 5 months as a Visiting Scientist at the University of Karlsruhe, Germany. His main research interests include design and simulation of mobile and wireless communication systems and development of new telecommunication services. He is a member of IEEE and Upsilon Pi Epsilon.     

Novel Channel and Polarization Assignment Schemes for 2–11 GHz Fixed–Broadband Wireless Access Networks

The scarcity of available spectrum in the 2–11 GHz frequency range and the continuously increasing number of users that require broadband communication services suggest that emerging fixed-broadband wireless access (F-BWA) networks will be deployed with aggressive frequency re-use to cope with capacity demands. In this context, co-channel interference may arise in high levels compromising the system's capacity and robust operation. Interference is further increased when limited directionality terminal antennas are employed to support non line-of-sight operation and in the case where an adaptive-time division duplex is selected for efficient radio resource management in asymmetric and time-varying traffic conditions. In this paper frequency channel assignment (CA) and antenna polarization assignment (PA) are considered as a means of mitigating interference. Two novel CA schemes that consider the distinct characteristics of F-BWA are proposed; the rotated-interleaved channel assignment and the non-uniform channel assignment. According to statistical interference simulation analysis the proposed schemes are more efficient in suppressing interference, achieving higher capacity compared to existing schemes while incurring no further complexity. In addition, instead of exploiting the performance of CA and PA schemes independently a framework for a joint CA-PA consideration is presented, where for a particular CA scheme an optimized PA pattern is developed. Results show that this approach improves the CA-PA interoperability increasing the overall performance. The efficiency of the proposed schemes is investigated for both FDD and adaptive-TDD schemes and is verified for various sectorization, frequency re-use and terminal antenna directivity configurations to ensure compatibility with different deployment scenarios. Bayan Sharif received the bachelor and doctorate degrees from Queens University of Belfast and Ulster University, N. Ireland, in 1984 and 1988. In 1989 he held a research fellowship post at Queens University of Belfast, where he worked on parallel programming algorithms for two-dimensional signal-processing applications. He joined Newcastle University in 1990 as Lecturer, and was promoted to Senior Lecturer and Professor in Digital Communications in 1999 and 2000. During this period he held visiting academic positions with Colorado State University and the UAE Telecommunication Corporation (Etisalat). He is currently Head of the Communications and Signal Processing Research Group at the School of Electrical, Electronic and Computer Engineering and his research interests are in digital communications with a focus on the optimization of wireless networks and DSP algorithms for receiver structures. Prof. Sharif has published over 170 journal and conference papers, and held UK and EU research grants in digital communications and signal processing worth over 2M. He is a Chartered Engineer and Fellow of the IEE. Panos I. Dallas (pdal@intracom.gr) was born 1967 in Thessaloniki, Greece. He obtained his diploma and Ph.D. degree from the Electrical and Computer Engineering Department of Aristotle University of Thessaloniki, Greece, in 1990 and 1997, respectively. Since 1998 he joined with INTRACOM where he currently is Section Manager of Advanced Communications Technologies branch of Emerging Technologies & Markets department, leading the next generation of broadband wireless access systems for internal and EU projects. He runs the relevant standardization activities (IEEE 802.16 and ETSI/BRAN HIPERMAN) in INTRACOM and he represents the company in WiMAX forum. Finally, he has over 30 publications in international journals and conferences. Konstantinos E. Ntagkounak is received the B.Sc. in Electrical Engineering from Technology Institute of Chalkis, Greece, in 1998 and the M.Sc. in Communications & Signal Processing from University of Newcastle, UK, in 2001, where he is currently studying for a Ph.D. in Electrical Engineering. Since 2001, he is with INTRACOM S.A. as a research engineer involved with several European Union IST research projects in the area of Advanced Communication Technologies. His research interests include medium access protocols, radio resource management and network architectures for next generation broadband wireless access systems.     

Capacity and Error Probability for Maximal Ratio Combining Reception over Correlated Nakagami Fading Channels

In this paper, the capacity and error probability of maximal ratio combining (MRC) reception are considered for different modulation schemes over correlated Nakagami fading channels. Based on an equivalent scalar additive white Gaussian noise (AWGN) channel, we derive the characteristic function (CF) and the probability density function (PDF) of the signal to noise ratio for MRC reception over Nakagami fading channels. Using these CF and PDF results, closed form error probability and capacity expressions are obtained for PSK, PAM and QAM modulation. Wei Li received his Ph.D. degree in Electrical and Computer Engineering from the University of Victoria in 2004. He is now a Post-doctoral Research Fellow in the Department of Electrical and Computer Engineering at the University of Victoria. He is a Member of the IEEE. His research interests include ultra-wideband system, spread spectrum communications, diversity for wireless communications, and cellular communication systems. Hao Zhang was born in Jiangsu, China, in 1975. He received his Bachelor Degree in Telecom Engineering and Industrial Management from Shanghai Jiaotong University, China in 1994, his MBA from New York Institute of Technology, USA in 2001, and his Ph.D. in Electrical and Computer Engineering from the University of Victoria, Canada in 2004. His research interests include ultra-wideband radio systems, MIMO wireless systems, and spectrum communications. From 1994 to 1997, he was the Assistant President of ICO(China) Global Communication Company. He was the Founder and CEO of Beijing Parco Co., Ltd. from 1998 to 2000. In 2000, he joined Microsoft Canada as a Software Engineer, and was Chief Engineer at Dream Access Information Technology, Canada from 2001 to 2002. He is currently an Adjunct Assistant Professor in the Department of Electrical and Computer Engineering at the University of Victoria. T. Aaron Gulliver received the Ph.D. degree in Electrical and Computer Engineering from the University of Victoria, Victoria, BC, Canada in 1989. From 1989 to 1991 he was employed as a Defence Scientist at Defence Research Establishment Ottawa, Ottawa, ON, Canada. He has held academic positions at Carleton University, Ottawa, and the University of Canterbury, Christchurch, New Zealand. He joined the University of Victoria in 1999 and is a Professor in the Department of Electrical and Computer Engineering. He is a Senior Member of the IEEE and a member of the Association of Professional Engineers of Ontario, Canada. In 2002, he became a Fellow of the Engineering Institute of Canada. His research interests include information theory and communication theory, algebraic coding theory, cryptography, construction of optimal codes, turbo codes, spread spectrum communications, space-time coding and ultra wideband communications.     

A State-Space Approach to Multiuser Parameters Estimation Using Central Difference for CDMA Systems

In this paper, it is shown that a state-space model applies to the code-division multiple-access (CDMA) channel, and Central Difference Filter (CDF) produces channel estimates with the minimum mean-square error (MMSE). This result may be used as compare to Extended Kalman Filter (EKF) which used as channel estimator in CDMA system. The main purpose of this paper is to compare robustness of channel estimator for realistic rapidly time-varying Rayleigh fading channels. To overcome the highly nonlinear nature of time delay estimation and also improve the accuracy, consistency and efficiency of channel estimation, an iterative nonlinear filtering algorithm, called the CDF has been applied in the field of CDMA System. The proposed channel estimator has a more near-far resistant property than the conventional Extended Kalman Filter (EKF). Thus, it is believed that the proposed estimator can replace well-known filters, such as the EKF. The Cramer-Rao lower bound (CRLB) is derived for the estimator, and simulation result show that it is nearly near-far resistant and clearly outperforms the EKF. Jang Sub Kim was born June 15, 1974, in Yeongdeok, Korea. He received the M.S. degree in school of electrical and computer engineering from Sungkyunkwan University, Seoul, Korea. He is currently with the School of Information and Communication Engineering, Sungkyunkwan University, where he was a Ph. D. student since 1999. His research interests include code-division multiple access, channel estimation, position location, and wireless communications. Seokho Yoon (S‘99–M‘1) received the B.S.E. (summa cum laude), M.S.E., and Ph.D. degrees in electrical engineering from KAIST, Daejeon, Korea, in 1997, 1999, and 2002, respectively. From April 2002 to June 2002, he was with the Department of Electrical Engineering and Computer Sciences, Massachusetts Institute of Technology, Cambridge, MA, and from July 2002 to February 2003, he was with the Department of Electrical Engineering, Harvard University, Cambridge, MA, as a Postdoctoral Research Fellow. In March 2003, he joined the School of Information and Communication Engineering, Sungkyunkwan University, Suwon, Korea, where he is currently an Assistant Professor. His research interests include spread spectrum systems, mobile communications, detection and estimation theory, and statistical signal processing. Dr. Yoon is a member of the IEEK and KICS. He was the recipient of a Bronze Prize at Samsung Humantech Paper Contest in 2000. Dong-Ryeol Shin (M‘97) was born in Seoul, Korea, in 1957. He received the B.S., M.S. and Ph.D degree in electrical engineering from the Sungkyunkwan University in 1980, and the Korea Advanced Institute of Science and Technology (KAIST) in 1982 and the Georgia Institute of Technology in 1992, respectively. During 1992-1994, he had worked for Samsung Data Systems, Ltd., Korea. Since 1994, he has been with network research group at the Sungkyunkwan University, Korea, as a professor. His current research interests include wireless communications and ubiquitous computing.     

CCII-Based Grounded to Floating Immittance Converter and a Floating Inductance Simulator

A new circuit employing second-generation current conveyors (CCIIs), and unmatched resistors for converting a grounded immittance to the corresponding floating immittance with either positive or negative adjustable multiplier, is presented. Moreover, the proposed circuit can also realize a synthetic floating inductance employing a grounded capacitor depending on the passive element selection. Simulation results using 0.35 μ m TSMC CMOS technology parameters are given. Erkan Yuce was born in 1969 in Nigde, Turkey. He received the B.Sc. from Middle East Technical University and M.Sc. degrees from Pamukkale University in 1994 and 1998 respectively. He is a Ph.D. student at Bogazici University all in Electrical and Electronics Engineering. He is currently Research Assistant at the Electrical and Electronics Engineering Department of Bogazici University. His current research interests include analog circuits, active filters, synthetic inductors, and current-mode circuits. He is the author or co-author of about 10 papers published in scientific journals or conference proceedings. Oguzhan Cicekoglu was born in 1963 in Istanbul, Turkey. He received the B.Sc. and M.Sc. degrees from Bogazici University and the Ph.D. degree from Istanbul Technical University all in Electrical and Electronics Engineering in 1985, 1988 and 1996 respectively. He served as lecturer at the School of Advanced Vocational Studies Electronics Prog. of Bogazici University where he held various administrative positions between 1993 and 1999, and as part time lecturer at various institutions. He was with Biomedical Engineering Institute between 1999 and 2001. He is currently Associate Professor at the Electrical and Electronics Engineering Department of Bogazici University. His current research interests include analog circuits, active filters, analog signal processing applications and current-mode circuits. He is the author or co-author of about 150 papers published in scientific journals or conference proceedings. Oguzhan Cicekoglu is a member of the IEEE. Shahram Minaei received his B.Sc. degree in Electrical and Electronics Engineering from Iran University of Science and Technology in 1993. He received his M.Sc. and Ph.D. degrees in Electronics and Communication Engineering from Istanbul Technical University in 1997 and 2001, respectively. He is currently an Associate Professor at the Electronics and Communication Engineering Department of Dogus University in Istanbul, Turkey. He has more than 50 journal or conference papers in scientific review. He served as reviewer for a number of international journals and conferences. His current field of research concerns current-mode circuits and analog signal processing. Shahram Minaei is a member of the IEEE.     

Systematic Synthesis of Active-RC Circuit Building-Blocks

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

Integrated Circuit Implementation of a Compact Discrete-Time Chaos Generator

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

Optimization and Performance Analysis of Zero Forcing Decision Feedback Detector for MIMO Block-Fading Channels with Per-Antenna Power Control

In multiple-input multiple-output (MIMO) antenna systems, the zero forcing decision feedback detector (ZF-DFD) is used to recover transmit signals. In this paper, we propose a per-antenna power control (PAPC) scheme based on ZF-DFD for MIMO block-fading channels. The optimal power controlled ZF-DFD can minimize the block error rate (BLER) and maximize the lower bound of the channel’s free distance at high signal-to-noise ratio (SNR) region subject to a power constraint. Additionally, the optimal power controlled ZF-DFD can achieve this BLER performance without any ordering operation at the receiver. The performance analysis among the conventional ZF-DFD without feedback, the optimal power controlled ZF-DFD with power feedback, and the ZF-DFD with full channel state information feedback shows that the optimal ZF-DFD achieves a tradeoff between performance and feedback overhead. We compare the bit error rate (BER) and BLER performance of the optimal ZF-DFD with other detectors without power feedback by simulation. In simulations, the execution times required by these detectors are also reported to compare their complexity. It comes straight that the optimal power controlled ZF-DFD proposed in this paper can achieve good performance with small feedback overhead and have low complexity. Kun Zhao was born in Hefei, China, on 9 October 1979. He received his BS and MS degrees from University of Science and Technology of China (USTC), in 2001 and 2003, all in Electrical Engineering. He is now a Ph.D. candidate at USTC.His research interests are in the area of spread spectrum and CDMA communications, radio resource management in mobile communications, space-time signal processing and multiuser MIMO. Ling Qiu received her BS degree from Southeast University, P. R. China, in 1990. She also received MS and Ph.D. degrees from University of Science and Technology of China (USTC), in 1997 and 1999, all in Electrical Engineering.From 1990 to 1994, she was an engineer in the Institute of Nanjing Electronic Technology. In 1999, she joined the Department of Electronic and Engineering and Information Science, USTC as a lecturer. Since 2002, she has been an Associate Professor. She is a coauthor of two books and over 40 conference/journal papers. Her research interests are in the area of wireless communications, spread spectrum and CDMA communications, wireless access networks and protocols, radio resource management in mobile communications, space-time signal processing and multiuser MIMO. Jinkang Zhu is a professor of Department of Electronic Engineering & Information Science of University of Science and Technology of China (USTC). Now he is director of Personal Communication Network and Spread Spectrum Lab. of USTC, Chair of the Academic Committee of School of Information Science & Technology of USTC, Vice-Chiar of the Academic Committee of USTC.He was Permanent V-President of School of Information Science & Technology of USTC, Chairman of PCN Experts Group of Communication Project of National R & D on High-Technology Programme of China, Member of Information Technology Expert Group of the Chinese Academy of Sciences, Member (Representation of China Mainland) of Technical Forum on Wireless Communications of Asia Pacific Region, Member of Technical Advisory Committee of IEEE VTC'99 Fall, Member of Technical Program Committee of IEEE VTC'2000, Member of Technical Program Committee of SCI'2001.His research area is Wireless and Mobile Communications, CDMA and Spread Spectrum Communications, Signal Process of Communications, and Wireless Networks. He got two awards of Ministry of Science & Technology of China, three awards of Chinese Academy of Science. He published five books and 100 papers, where synchronous CDMA method proposed is used in TD-SCDMA Standard of 3G as basic technology.     

Set of Sequences for QS-CDMA Systems with Multi-User Detection and Multipath-Fading Channels

In this work Walsh–Hadamard, QS, Lin–Chang, LCZ-GMW, ZCZ sets of sequences are compared. The comparison is accomplished by analyzing the conventional receiver (Rake) and a parallel interference canceller (PIC) receiver performance using each one of these sequence sets in a multipath Rayleigh fading channel and similar system loads in quasi-synchronous condition.André Seichi Ribeiro Kuramoto received the B.S. degree in Electrical Engineering from UEL, Londrina State University (Brazil) in 2002. He is currently an M.Sc. student at EPUSP – Escola Politécnica of University of São Paulo (Brazil) and his current research interests are quasi-synchronous DS-CDMA systems and code sequences analysis.Taufik Abrão received the B.S., M.Sc. and Ph.D., all in Electrical Engineering from EPUSP – Escola Politécnica of University São Paulo (Brazil), in 1992, 1996, and 2001, respectively. He is currently an Adjunct Professor at the Electrical Engineering Department of UEL, State University of Londrina (Brazil) and his current research interests are CDMA systems, multi-user detection, and code sequences analysis.Paul Jean Etienne Jeszensky received the B.S., M.S. and Ph.D., all in Electrical Engineering from EPUSP – Escola Politécnica of University of São Paulo (Brazil), in 1972, 1981, and 1989, respectively. Since 1990, he has been with EPUSP where he is a full-time Associate Professor and Researcher in Communication Systems. He was visiting professor at UPC – Universitat Politécnica de Catalunya, Barcelona (Spain) in 1995 and at TUB – Technical University of Budapest (Hungary) in 2001. He is author of the book Sistemas Telefônicos (in Portuguese), Editora Manole, 2003, and his current research interests include CDMA systems, multi-user detection, code sequences analysis and related topics.