A MC-CDMA Mobile Communication System Employing Pre-Rake and Transmit Diversity

In this paper, a multi-carrier code division multiple access (MC-CDMA) downlink mobile communication system employing pre-rake and dual transmit diversity is proposed. It combines high spectral efficiency with an immunity to channel dispersion and fading. It also ensures small size, cost and power consumption of the terminal. Theoretical and simulation results for the system under consideration are obtained. Depicted results show appreciable improvements of the proposed system over those previously known.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.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 Electronics and Communications Department, Faculty of Engineering Cairo University and is currently associate professor there. Her research interests include mobile communications, satellite communications and optical fiber communications.Fatma A. Newagy received her B.Sc and M.Sc degrees in electrical communication engineering from Cairo University, Egypt in 1998 and 2002 respectively. Since 1999, she has been a research assistant with the Department of Electronics and Communications, Faculty of Engineering, Cairo University. She is pursuing her Ph.D. there. Her research interests include mobile communications and modulation techniques for spread spectrum and wireless communications.     

Location Management in PCS Networks by Caching Two-Level Forwarding-Pointers

One of the challenging tasks in Personal Communication Services (PCS) is to efficiently maintain the location of PCS subscribers who move from one region to another (hereafter called mobile users). When a mobile user receives a call, the network has to quickly determine its current location. The existing location management scheme suffers from high signaling traffic in locating the mobile users. Two-level forwarding pointer scheme has been proposed from per-user forwarding pointer scheme to reduce the cost of signaling traffic. In this paper, we enhance the two-level forwarding pointer scheme. When a mobile user moves from its current Registered Area (RA), which is served by Mobile Switching Center (MSC), to another RA the local switch that acts as a parent of those two MSCs maintains this movement in its memory (hereafter called cache entry). A cache entry is used to locate rapidly the mobile user instead of querying the Home Location Register (HLR) and waiting for its reply. HLR is centralized in the network and far away from the mobile users so that the signaling traffic crossing it is expensive. Sometimes the cache entry may be failed to reach the mobile user then a two-level forwarding pointers will be created from the corresponding Visitor Location Register (VLR), attached to its MSC, through a correct path to locate the mobile user. Thus, there is a saving in cost of querying the underlying HLR. The analytical results indicate that such proposal efficiently reduces the signaling traffic cost for all values of Call to Mobility Ratio (CMR), this is especially considerable when CMR ≥1, without any increase in the call setup delay. Salah M. Ramadan (samohra@yahoo.com) received the BS and MS degrees from Computers Engineering Department, Al-Azhar University, Cairo, Egypt, in 1995 and 2002, respectively. From 2002, he was a Ph.D. student in Computers Engineering Department at Al-Azhar University and is currently pursuing the Ph.D. degree, where he is a research assistant in the Wireless Networks Branch. His research interests include traffic management in ATM networks, routing protocols, mobility management in PCS networks, and mobile computing. He is currently an instructor in Cisco Academy, Egypt. Ahmed M. El-Sherbini (Sherbini@mcit.gov.eg) received the Ph.D. in Electrical and Communication Engineering, Case Western University, U.S.A. March 1983 and M.Sc. in Communication Engineering, Cairo University, Giza, Egypt, June 1980. (M. Sc. Research Studies at the Ecole Nationale Superieure des Telecommunications (ENST), Paris, France). He is the Director, National Telecommunication Institute – Ministry of Communications and Information Technology, Egypt and Professor of Electrical and Communication Engineering Dept. Faculty of Engineering, Cairo University, Egypt. M. I. Marie received his B.Sc., M.Sc. and Ph.D. in electronic and communication engineering from Cairo University on 1972, 1981, 1985, respectively. Now he is a professor of communications at Computer and System Engineering department Al-Azhar University, Cairo, Egypt. His fields of interest includes digital communication, computer networks and protocols development. M. Zaki (azhar@mailer.scu.eun.eg) is the professor of software engineering, Computer and System Engineering Department, Faculty of Engineering, Al-Azhar University at Cairo. He received his B.Sc. and M.Sc. degrees in electrical engineering from Cairo University in 1968 and 1973 respectively. He received his Ph.D. degrees in computer engineering from Warsaw Technical University, Poland in 1977. His fields of interest include artificial intelligence, soft computing, and distributed system.     

Diversity Reception of an Asynchronous Blind Adaptive Multiuser Detector Through Correlated Nakagami Fading Channel

In this paper, blind adaptive multiuser detection (MUD) technique is developed for uplink transmission in multiuser space diversity DS-CDMA system to overcome multipath fading effect and multiple access interference. The system consists of a space diversity, a precombining blind adaptive detector (PBAD), and a weight adaptation technique based on the minimization of the mean output energy (MOE). The bit error rate (BER) performance of this receiver for asynchronous DS-CDMA signals with independent and correlated antenna branches under Nakagami fading channel for BPSK system is evaluated. It has been seen that the use of antenna diversity can yield substantial improvement in performance even if the correlation between the antenna elements is relatively large (up to 0.795). However, the large correlation values pose a significant reduction in the diversity gain in comparison with the zero correlation situation. It has also been confirmed by simulations that the PBAD provides a significant receiver performance in comparison with the RAKE receiver employing antenna diversity. Khodr A. Saaifan Born in lebanon 1978, received B.S.c. degree in electrical and electronics engineering (with honors) from Benha higher institute of technology, Benha, Egypt, in 2001, and the M.S.c. degree in communications from Cairo University, Giza, Egypt, in 2005. He is currently pursuing for the Ph.D. degree at the Cairo University. His current research interest includes space–time-coded transmission, multiple-input multiple-output (MIMO) systems, fading channels, equalization, turbo (iterative) processing, and wideband code division multiple access (WCDMA). 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 Who's Who in the World and in the IBC (International Biographical Center, Cambridge) for outstanding people of the 20th century.     

New Four-Quadrant CMOS Current-Mode and Voltage-Mode Multipliers

In this paper, a four-quadrant current-mode multiplier based on a new squarer cell is proposed. The multiplier has a simple core, wide input current range with low power consumption, and it can easily be converted to a voltage-mode by using a balanced output transconductor (BOTA) [1]. The proposed four-quadrant current-mode and voltage-mode multipliers were confirmed by using PSPICE simulation and found to have good linearity with wide input dynamic range. For the proposed current-mode multiplier, the static power consumption is 0.671 mW, the maximum power consumption is 0.72 mW, the input current range is ± 60 μ A, the bandwidth is 31 MHz, the input referred noise current is 46 pA/√Hz, and the maximum linearity error is 3.9%. For the proposed voltage-mode multiplier, the static power consumption is 1.6 mW, the maximum power consumption is 1.85 mW, the input voltage range is ± 1V from ± 1.5V supply, the bandwidth is 25.34 MHz, the input referred noise voltage is 0.85 μV/√Hz, and the maximum linearity error is 4.1%. Mohammed A. Hashiesh was born in Elkharga, New Valley, Egypt, in 1979. He received the B.Sc. degree with honors from the Electrical Engineering Department, Cairo University, Fayoum-Campus, Egypt in 2001, and he received the M.Sc. degree in 2004 from the Electronics and Communication Engineering Department, Cairo University, Egypt. He is currently a Teacher Assistant at the Electrical Engineering Department, Cairo University, Fayoum-Campus. His research interests include analog CMOS integrated circuit design and signal processing, and digitally programmable CMOS analog building blocks. Soliman A. Mahmoud was born in Cairo, Egypt, in 1971. He received the B.Sc. degree with honors, the M.Sc. degree and the Ph.D. degree from the Electronics and Communications Department, Cairo University—Egypt in 1994, 1996 and 1999 respectively. He is currently an Assistant Professor at the Electrical Engineering Department, Cairo University, Fayoum-Campus. He has published more than 50 papers. His research and teaching interests are in circuit theory, fully integrated analog filters, high frequency transconductance amplifiers, low voltage analog CMOS circuit design, current-mode analog signal processing and mixed analog/digital programmable analog blocks. Ahmed M. Soliman was born in Cairo Egypt, on November 22, 1943. He received the B.Sc. degree with honors from Cairo University, Cairo, Egypt, in 1964, the M.S. and Ph.D. degrees from the University of Pittsburgh, Pittsburgh, PA., U.S.A., in 1967 and 1970, respectively, all in Electrical Engineering. He is currently Professor Electronics and Communications Engineering Department, Cairo University, Egypt. From September 1997–September 2003, Dr Soliman served as Professor and Chairman Electronics and Communications Engineering Department, Cairo University, Egypt. From 1985–1987, Dr. Soliman served as Professor and Chairman of the Electrical Engineering Department, United Arab Emirates University, and from 1987–1991 he was the Associate Dean of Engineering at the same University. He has held visiting academic appointments at San Francisco State University, Florida Atlantic University and the American University in Cairo. He was a visiting scholar at Bochum University, Germany (Summer 1985) and with the Technical University of Wien, Austria (Summer 1987). In 1977, Dr. Soliman was decorated with the First Class Science Medal, from the President of Egypt, for his services to the field of Engineering and Engineering Education. Dr Soliman is a member of the Editorial Board of Analog Integrated Circuits and Signal Processing. Presently Dr. Soliman is Associate Editor of the IEEE Transactions on Circuits and Systems I (Analog Circuits and Filters).     

An Integrated Model to Design PCS Networks

An integrated model is proposed that comprises essentially, an Enhanced Profile-Based Strategy (EPBS) for small-scale roaming and a Caching Two-Level Forwarding Pointer (C2LFP) strategy for large-scale roaming. The idea behind the integrated model is how those two location management solutions are applied, and what is the suitable approach to specify the physical parameters of PCS networks from mobility management’s point of view so that our solutions can be more cost effective for location management. An evolutionary method, using a constrained Genetic Algorithm (GA) has been used to achieve network parameters optimization. For convenience, we selected the underlying planning problem with an appropriate set of parameters so that it can be treated, in what follows, both genetically and analytically. Thus one can easily verify the accuracy and efficiency of the evolutionary solution that would be obtained from the genetic algorithm. For more realistic environments, GA could be used reliably to build up sophisticated models that integrate the small-scale and large-scale roaming parameters of PCS networks. The results that have been obtained from a case study are presented in order to provide a deep explanation for the proposed integration approach. Salah M. Ramadan (samohra@yahoo.com) received the BS and MS degrees from Computers Engineering Department, Al-Azhar University, Cairo, Egypt, in 1995 and 2002, respectively. From 2002, he was a PhD student in Computers Engineering Department at Al-Azhar University and is currently pursuing the PhD degree, where he is a research assistant in the Wireless Networks Branch. His research interests include traffic management in ATM networks, routing protocols, mobility management in PCS networks, and mobile computing. He is currently an instructor in Cisco Academy, Egypt. Ahmed M. El-Sherbini (Sherbini@mcit.gov.eg) received the Ph.D. in Electrical and Communication Engineering, Case Western University, U.S.A. March 1983 and M.Sc. in Communication Engineering, Cairo University, Giza, Egypt, June 1980. (M.Sc. Research Studies at the Ecole Nationale Superieure des Telecommunications (ENST), Paris, France) He is the Director, National Telecommunication Institute – Ministry of Communications and Information Technology, Egypt and Professor of Electrical and Communication Engineering Dept. Faculty of Engineering, Cairo University, Egypt. M. I. Marie(azhar@mailer.scu.eun.eg) received his B.Sc, M.Sc and PhD in electronic and communication engineering from Cairo University on 1972, 1981, 1985, respectively. Now he is a professor of communications at Computer and System Engineering Department Al-Azhar University, Cairo, Egypt. His fields of interest includes digital communication, computer networks and protocols development. M. Zaki is the professor of software engineering, Computer and System Engineering Department, Faculty of Engineering, Al-Azhar University at Cairo. He received his B.Sc. and M.Sc. degrees in electrical engineering from Cairo University in 1968 and 1973 respectively. He received his Ph.D. degrees in computer engineering from Warsaw Technical University, Poland in 1977. His fields of interest include artificial intelligence, soft computing, and distributed system.     

New 1.5-V CMOS second generation current conveyor based on wide range transconductor

This paper presents a novel CMOS low-voltage and low-power positive second-generation current conveyor (CCII+). The proposed CCII+ uses two n-channel differential pairs instead of the complementary differential pairs; i.e. (n-channel and p-channel), to realize the input stage. This solution allows almost a rail-to-rail input and output operation; also it reduces the number of current mirrors needed in the input stage. The CCII+ is operating at supply voltages of ±0.75 V with a total standby current of 133 μA. The application of the proposed CCII+ to realize a MOS-C second order maximally flat low-pass filter is given. PSpice simulation results for the proposed CCII+ and its application are given. Ahmed H. Madian was born in Jeddah, Saudi Arabia in 1975. He received the B.Sc. degree with honors, and the M.Sc. degree in electronics and communications from Cairo University, Cairo, Egypt, in 1997, and 2001 respectively. He is currently a Research Assistant in the Electronics Engineering Department, Micro-Electronics Design Center, Egyptian Atomic Energy Authority, Cairo, Egypt. His research interests are in circuit theory; low-voltage analog CMOS circuit design, current-mode analog signal processing, and mixed/digital applications on filed programmable gate arrays. Soliman A. Mahmoud was born in Cairo, Egypt, in 1971. He received the BSc degree with honors in 1994, the MSc degree in 1996, and the PhD degree in 1999, all from the Electronics and Communications Department, Cairo University, Egypt. He is currently an Associate Professor at the Electrical Engineering Department, Fayoum University, Egypt. He is currently also a visiting Associate Professor at the Electrical and Electronics Engineering Department, German University in Cairo, Egypt. In 2005, He was decorated with the Science Prize in Advanced Engineering Technology from the Academy of Scientific Research and technology. His research and teaching interests are in circuit theory, fully-integrated analog filters, high-frequency transconductance amplifiers, low-voltage analog CMOS circuit design, current-mode analog signal processing, and mixed analog/digital programmable analog blocks. Ahmed M. Soliman was born in Cairo Egypt, on November 22, 1943. He received the B.Sc. degree with honors from Cairo University, Cairo, Egypt, in 1964,the M.S. and Ph.D. degrees from the University of Pittsburgh, Pittsburgh, PA., U.S.A., in 1967 and 1970, respectively, all in Electrical Engineering. He is currently Professor Electronics and Communications Engineering Department, Cairo University, Egypt. From September 1997-September 2003, Dr Soliman served as Professor and Chairman Electronics and Communications Engineering Department, Cairo University, Egypt. From 1985-1987, Dr. Soliman served as Professor and Chairman of the Electrical Engineering Department, United Arab Emirates University, and from 1987-1991 he was the Associate Dean of Engineering at the same University. He has held visiting academic appointments at San Francisco State University, Florida Atlantic University and the American University in Cairo.He was a visiting scholar at Bochum University, Germany (Summer 1985) and with the Technical University of Wien, Austria (Summer 1987). In November 2005, Dr Soliman gave a lecture at Nanyang Technological University, Singapore.Dr Soliman was also invited to visit Taiwan and gave lectures at Chung Yuan Christian University and at National Central University of Taiwan. In 1977, Dr. Soliman was decorated with the First Class Science Medal, from the President of Egypt, for his services to the field of Engineering and Engineering Education. Dr Soliman is a Member of the Editorial Board of the IEE Proceedings Circuits, Devices and Systems. Dr Soliman is a Member of the Editorial Board of Analog Integrated Circuits and Signal Processing. Dr Soliman served as Associate Editor of the IEEE Transactions on Circuits and Systems I (Analog Circuits and Filters) from December 2001 to December 2003 and is Associate Editor of the Journal of Circuits, Systems and Signal Processing from January 2004-Now.     

On the Throughput Capacity of Hybrid Wireless Networks Using an <Emphasis Type="Italic">L</Emphasis>-Maximum-Hop Routing Strategy

A novel pulse shape is suggested to decrease the Inter-Carrier Interference (ICI) in an Orthogonal Frequency Multiplexing System (OFDM) due to frequency offset. Furthermore several Nyquist- I pulses recently found are also used for the same purpose. Simulation results are compared for the average ICI and for the signal to interference ratio (SIR) for the pulses under consideration. The sensitivity of the ICI to the used pulse shape and the effectiveness of the proposed pulse shape are reported. 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.     

Fully Differential CMOS Current Feedback Operational Amplifier

This paper presents a new CMOS fully differential current feedback operational amplifier (FDCFOA). The proposed CMOS realization of the FDCFOA is based on a novel class AB fully differential buffer circuit. Besides the proposed FDCFOA circuit is operating at supply voltages of ±1.5 V, it has a total standby current of 400 A. The applications of the FDCFOA to realize variable gain amplifier, fully differential integrator, and fourth order fully differential maximally flat low pass filter are given. The fourth order filter provides 8 dB gain and a bandwidth of 4.3 MHz to accommodate the wideband CDMA standard. The proposed FDCFOA and its applications are simulated using CMOS 0.35 m technology.Soliman A. Mahmoud was born in Cairo, Egypt, in 1971. He received the B.Sc. degree with honors, the M.Sc. degree and the Ph.D. degree from the Electronics and Communications Department, Cairo University—Egypt in 1994, 1996 and 1999 respectively. He is currently an Assistant Professor at the Electrical Engineering Department, Cairo University, Fayoum-Campus. His research interests include low voltage analog CMOS circuit design, filtering and applications suitable for VLSI.Inas Awad was born in Cairo, Egypt, in 1971. She received the Bachelor, the M.Sc. and the Ph.D. degrees in Electronics and Communications from Cairo University in 1994, 1997 and 2000, respectively. In 1995, she joined the department of Electronics and Communications, Cairo University, Fayoum-Campus as a teaching assistant and now she is an Assistant Professor at the same department. Her primary research interest is in analog circuits with particular emphasis on current-mode approach and low-voltage low-power CMOS designs.     

Two Proposed Blind Equalizers Using Different Constellation Matched Error Functions for QAM Signals

Although Constant Modulus Algorithm (CMA) is effective to equalize non-minimum phase channels blindly, it suffers from residual intersymbol interference (ISI) and large Mean Square Error (MSE) when applied to higher order constellations (QAM). Methods based on cost function matched to the signal constellation namely alphabet matched algorithm (AMA) were previously reported and proves its superiority on CMA concerning the MSE. Thus dual mode algorithms between CMA and AMA were introduced. A hybrid technique combining CMA and AMA using a cosine square function as a constellation matched error (CME) was lately reported. In this paper two different CME functions are introduced. The MSE of the proposed algorithms are calculated using Matlab simulation under multipath slow fading channels for different signal to noise ratios (SNR) and different levels of QAM constellations. A comparison is established among them. Depicted results show the effectiveness of the two proposed CME functions. 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.     

New op-amp-RC to G m -C transformation method

A new transformation method is proposed and used to transform op-amp-RC circuits to G _m -C ones with only grounded capacitors. The proposed method enables the generation of high-performance G _m -C filters that benefit from the advantages of good and well-known op-amp-RC structures and at the same time feature electronic tunability, high frequency capability and monolithic integration ability. An attractive feature of the proposed method is that it results in G _m -C structures with only grounded capacitors in spite of the presence of floating capacitors in the original op-amp-RC circuits. Ahmed M. Soliman was born in Cairo Egypt, on November 22, 1943. He received the B.Sc. degree with honors from Cairo University, Cairo, Egypt, in 1964, the M.S. and Ph.D. degrees from the University of Pittsburgh, Pittsburgh, PA, U.S.A., in 1967 and 1970, respectively, all in Electrical Engineering. He is currently Professor Electronics and Communications Engineering Department, Cairo University, Egypt. From September 1997–September 2003, Dr. Soliman served as Professor and Chairman Electronics and Communications Engineering Department, Cairo University, Egypt. From 1985–1987, Dr. Soliman served as Professor and Chairman of the Electrical Engineering Department, United Arab Emirates University, and from 1987–1991 he was the Associate Dean of Engineering at the same University. He has held visiting academic appointments at San Francisco State University, Florida Atlantic University and the American University in Cairo. He was a visiting scholar at Bochum University, Germany (Summer 1985) and with the Technical University of Wien, Austria (Summer 1987). In November 2005, Dr. Soliman gave a lecture at Nanyang Technological University, Singapore. Dr. Soliman was also invited to visit Taiwan and gave lectures at Chung Yuan Christian University and at National Central University of Taiwan. In 1977, Dr. Soliman was decorated with the First Class Science Medal, from the President of Egypt, for his services to the field of Engineering and Engineering Education. Dr. Soliman is a Member of the Editorial Board of the IEE Proceedings Circuits, Devices and Systems. Dr. Soliman is a Member of the Editorial Board of Analog Integrated Circuits and Signal Processing. Dr. Soliman served as Associate Editor of the IEEE Transactions on Circuits and Systems I (Analog Circuits and Filters) from December 2001 to December 2003 and is Associate Editor of the Journal of Circuits, Systems and Signal Processing from January 2004–Now.     

Channel-Aware Earliest Deadline Due Fair Scheduling for Wireless Multimedia Networks

Providing delay guarantees to time-sensitive traffic in wireless multimedia networks is a challenging issue. This is due to the time-varying link capacities and the variety of real-time applications expected to be handled by such networks. We propose and evaluate the performance of a channel-aware scheduling discipline and a set of policies that are capable of providing such delay guarantees in TDM-based wireless networks. First, we introduce the Channel-Dependent Earliest-Due-Date (CD-EDD) discipline. In this discipline, the expiration time of the head of line packets of users' queues is taken into consideration in conjunction with the current channel states of users in the scheduling decision. This scheme attempts to guarantee the targeted delay bounds in addition to exploiting multiuser diversity to make best utilization of the variable capacity of the channel. We also propose the violation-fair policy that can be integrated with the CD-EDD discipline and two other well-known scheduling disciplines [1, 2]. In this policy, we attempt to ensure that the number of packets dropped due to deadline violation is fairly distributed among the users. The proposed schemes can provide statistical guarantees on delays, achieve high throughput, and exhibit good fairness performance with respect to throughput and deadline violations. We provide extensive simulation results to study the performance the proposed schemes and compare them with two of the best known scheduling disciplines [1, 2] in the literature. Khaled M. F. Elsayed (S90-M95-SM02) received his B.Sc. (honors) in electrical engineering and M.Sc. in engineering mathematics from Cairo University in 1987 and 1990 respectively. He received his Ph.D. in computer science and computer engineering from North Carolina State University in 1995. He is now an Associate Professor in Cairo University, Egypt and is an independent telecommunications consultant. Between 1995 and 1997, he was a member of scientific staff with Nortel Wireless Systems Engineering in Richardson, TX.Dr. Elsayed was the editor for the Internet technology series of the IEEE Communications Magazine from 1998 until 2002. He has served on technical program committees for several IEEE, IFIP, and ITC conferences. He was the technical co-chair for IFIP MWCN 2003 conference in Singapore. He also served as an expert evaluator for the European Commission FP5 and FP6 programmes. His research interest is in the area of performance evaluation of communication networks including IP, wireless and optical networks. Ahmed Khattab received his B.Sc. (honors) and MS.C in Electronics and Communications Engineering from Cairo University in 2002 and 2004 respectively. Since August 2005, he is pursuing his PhD degree at Rice University, Texas. His research interests are in wireless networking and radio resource management.     

A Novel CMOS Realization of the Differential Input Balanced Output Current Operational Amplifier and its Applications

In this paper a new realization of the differential input balanced output current opamp is proposed, operating with ±1.5 V supplies. Its architecture is based on the use of current inverters to sense the input currents while providing a very low input resistance, 23 Ω. The opamp provides a maximum output swing of 700 μA, with an input offset current of 3.5 nA. The differential gain achieved is 65.5 dB, and the differential structure adopted in the design provided a high CMRR, 89.5 dB, the proposed circuit is compared to other realizations with single and differential inputs. The applications of the current opamp are exploited some new applications are presented such as: MOSFET-C integrators, full non-linearity cancellation for MOS transistors, and finally a digitally tuned current-mode variable gain amplifier, which has a gain tuning range of 25 dB with a 0.05 dB step.Ahmed M. Soliman was born in Cairo Egypt, on November 22, 1943. He received the B.Sc. degree with honors from Cairo University, Cairo, Egypt, in 1964, the M.S. and Ph.D. degrees from the University of Pittsburgh, Pittsburgh, PA, U.S.A., in 1967 and 1970, respectively, all in Electrical Engineering.He is currently Professor and Chairman Electronics and Communications Engineering Department, Cairo University, Egypt. From 1985–1987, Dr. Soliman served as Professor and Chairman of the Electrical Engineering Department, United Arab Emirates University, and from 1987–1991 he was the Associate Dean of Engineering at the same University. He has held visiting academic appointments at San Francisco State University, Florida Atlantic University and the American University in Cairo.He was a visiting scholar at Bochum University, Germany (Summer, 1985) and with the Technical University of Wien, Austria (Summer, 1987).In 1977, Dr. Soliman was decorated with the First Class Science Medal, from the President of Egypt, for his services to the field of Engineering and Engineering Education. Dr. Soliman is a member of the Editorial Board of Analog Integrated Circuits and Signal Processing. Presently Dr. Soliman is Associate Editor of the IEEE Transactions on Circuits and Systems I (Analog Circuits and Filters).     

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.     

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.     

A secure incentive protocol for mobile ad hoc networks

The proper functioning of mobile ad hoc networks depends on the hypothesis that each individual node is ready to forward packets for others. This common assumption, however, might be undermined by the existence of selfish users who are reluctant to act as packet relays in order to save their own resources. Such non-cooperative behavior would cause the sharp degradation of network throughput. To address this problem, we propose a credit-based Secure Incentive Protocol (SIP) to stimulate cooperation among mobile nodes with individual interests. SIP can be implemented in a fully distributed way and does not require any pre-deployed infrastructure. In addition, SIP is immune to a wide range of attacks and is of low communication overhead by using a Bloom filter. Detailed simulation studies have confirmed the efficacy and efficiency of SIP. This work was supported in part by the U.S. Office of Naval Research under Young Investigator Award N000140210464 and under grant N000140210554. Yanchao Zhang received the B.E. degree in Computer Communications from Nanjing University of Posts and Telecommunications, Nanjing, China, in July 1999, and the M.E. degree in Computer Applications from Beijing University of Posts and Telecommunications, Beijing, China, in April 2002. Since September 2002, he has been working towards the Ph.D. degree in the Department of Electrical and Computer Engineering at the University of Florida, Gainesville, Florida, USA. His research interests are network and distributed system security, wireless networking, and mobile computing, with emphasis on mobile ad hoc networks, wireless sensor networks, wireless mesh networks, and heterogeneous wired/wireless networks. Wenjing Lou is an assistant professor in the Electrical and Computer Engineering department at Worcester Polytechnic Institute. She obtained her Ph.D degree in Electrical and Computer Engineering from University of Florida in 2003. She received the M.A.Sc degree from Nanyang Technological University, Singapore, in 1998, the M.E degree and the B.E degree in Computer Science and Engineering from Xi'an Jiaotong University, China, in 1996 and 1993 respectively. From Dec 1997 to Jul 1999, she worked as a Research Engineer in Network Technology Research Center, Nanyang Technological University. Her current research interests are in the areas of ad hoc and sensor networks, with emphases on network security and routing issues. Wei Liu received his B.E. and M.E. in Electrical and Information Engineering from Huazhong University of Science and Technology, Wuhan, China, in 1998 and 2001. In August 2005, he received his PhD in Electrical and Computer Engineering from University of Florida. Currently, he is a senior technical member with Scalable Network Technologies. His research interest includes cross-layer design, and communication protocols for mobile ad hoc networks, wireless sensor networks and cellular networks. 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, got an early promotion to an associate professor with tenure in August 2003 and a professor in August 2005. He has published over 150 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 many 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 is a senior member of the IEEE.     

Single DDCC Biquads with High Input Impedance and Minimum Number of Passive Elements

Two new configurations for the design of biquad filters with high input impedance are presented. The first configuration can synthesize low-pass and high-pass filter functions according to the passive components used. The second one can synthesize a band-pass filter function. The proposed configurations employ only one differential difference current conveyor (DDCC) as active elements and minimum number of passive elements, namely two resistors and two capacitors. Another filter topology based on DDCC is presented that allows modifying the quality factor without changing its natural frequency. All the filters enjoy low sensitivities. SPICE simulation results are given to confirm the validity of the analysis and to point out the high performance of the filters.Muhammed A. Ibrahim was born in Erbil, Iraq in 1969. He obtained his B.Sc. and M.Sc. degrees from Salahaddin University, Erbil, Iraq and Istanbul Technical University, Istanbul, Turkey in 1990 and 1999, respectively, all in electronics and communication engineering. Between 1992 and 1996 he worked as Research Assistant at Salahaddin University where he was later appointed as Assistant Lecturer in 1999. Since 2000 he has been studying for his Ph.D. degree in Electronics and Communication Engineering Program at Istanbul Technical University. His main research interests are CMOS circuit design, current-mode circuits and analog signal processing applications. He has more than 20 international journal and conference papers in scientific review.H. Hakan Kuntman received his B.Sc., M.Sc. and Ph.D. degrees from Istanbul Technical University in 1974, 1977 and 1982, respectively. In 1974 he joined the Electronics and Communication Engineering Department of Istanbul Technical University. Since 1993 he is a professor of electronics in the same department. His research interest include design of electronic circuits, modeling of electron devices and electronic systems, active filters, design of analog IC topologies. Dr. Kuntman has authored many publications on modelling and simulation of electron devices and electronic circuits for computer-aided design, analog VLSI design and active circuit design. He is the author or the coauthor of 76 journal papers published or accepted for publishing in international journals, 91 conference papers presented or accepted for presentation in international conferences, 99 turkish conference papers presented in national conferences and 10 books related to the above mentioned areas. Furthermore he advised and completed the work of 7 Ph.D. students and 31 M.Sc. students. Currently, he acts as the head of the Electronics and Communication Engineering Department in Istanbul Technical University. Dr. Kuntman is a member of the Chamber of Turkish Electrical Engineers (EMO).Oguzhan Cicekoglu 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. He served also as part time lecturer at various institutions. He was with the Biomedical Engineering Institute of the Bogazici University between 1999 and 2001. He is currently Associate Professor at the Electrical and Electronics Engineering Department of the same University.His current research interests include analog circuits, active filters, analog signal processing applications and current-mode circuits. Oguzhan Cicekoglu is the author or co-author of 62 journal papers and about 90 international or local conference papers published or accepted for publishing in journals or conference proceedings.He served as the committee member in various scientific conferences and as reviewer in numerous journals including Analog Integrated Circuits and Signal Processing, IEEE CAS-I, IEEE CAS-II, International Journal of Electronics, Microelectronics Journal, Solid State Electronics and IEE Proceedings Pt.G.Oguzhan Cicekoglu is a member of the IEEE.     

New Paradigms in Wireless Communication Systems

This paper discusses what a new paradigm can be in wireless communication systems of the twenty-first century. First, it suggests two directions for the new paradigm; one is “micro- and nano-device communication system” which is the projected scenario considering that the entities in source and destination have been shrinking throughout the history of wireless communication systems. The second direction is “networked robot system”, which emerges as a natural extension of mobile ad hoc networking where the networking is closely related to motion control of robots. Secondly, it shows two interesting research topics, “the new communication protocol design” and “signal processing”, respectively, that arise in the wake of the fusion between the two directions in the novel communication paradigm. Finally, it considers a new science of wireless communications in the twenty-first century. Shinsuke Hara received the B.Eng., M.Eng. and Ph.D. degrees in communications engineering from Osaka University, Osaka, Japan, in 1985, 1987 and 1990, respectively. From April 1990 to March 1997, he was an assistant professor in the Department of Communication Engineering, School of Engineering, Osaka University, and from October 1997 to September 2005, he was an associate professor in the Department of Electronic, Information and Energy Engineering, Graduate School of Engineering, Osaka University. Since October 2005, he has been a professor in the Department of Physical Electronics and Informatics, Graduate School of Engineering, Osaka City University. In addition, from April 1995 to March 1996, he was a visiting scientist at Telecommunications and Traffic Control Systems Group, Delft University of Technology, Delft, The Netherlands. His research interests include wireless communications systems and digital signal processing. 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 at Internet System Laboratory, NEC Corporation, Japan. Since October 2004, he has been an Assistant Research Professor in Center for TeleInfrastructure (CTIF), Aalborg University, Denmark. His main research interests are access technologies, radio resource management, and link-layer techniques in the area of short-range communication, cellular network, cognitive radio, and sensor network. 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, Republic of Macedonia, in 1997 and 2000, respectively. He received a Ph.D. degree from Aalborg University, Denmark, in 2004. From 1998 to 2001 he was a teaching and research assistant at the Institute of Telecommunications, Faculty of Electrical Engineering in Skopje. He is currently Assistant Professor at the Department of Communication Technology at the Aalborg University. His research interests are related to the PHY-MAC aspects of wireless protocols, wireless sensor networks, random access protocols, and network coding. Kazunori Hayashi received the B.E., M.E. and Ph.D. degrees in communication engineering from Osaka University, Osaka, Japan, in 1997, 1999 and 2002, respectively. He spent 3 months in 2000 at Aalborg University, Denmark, as a Visiting Scholar. Since 2002, he has been with the Department of Systems Science, Graduate School of Informatics, Kyoto University. He is currently an Assistant Professor there. His research interests include digital signal processing for communications systems.     

Channel Estimation by Using Short Training Sequences in CDMA Systems

Multiuser detection techniques are known to be effective to counter the presence of multiuser interference in code division multiple access channels. Multiuser detectors can provide excellent performance only when the channel impulse responses of all the users are precisely known. Hence, channel estimation becomes a challenging issue in mobile communication systems. In this paper, we address the problem of efficient maximum likelihood mobile radio channel estimation at high channel efficiency that requires a short training sequence along with the known spreading sequence. The proposed system can be employed in both the uplink and downlink of a heavily loaded multiuser CDMA system. The extension of the approach with unknown users' delays are also proposed. We present results that show the success of this method in recovering the transmitted bits with a relatively small number of preamble bits. 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 techniques. 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. Kadri Hacıoğlu 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 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 current research interests include receiver design, multi-user detection techniques, blind and trained channel estimation in Code Division Multiple Access (CDMA).     

Design and Evaluation of a QoS-aware Framework for HIPERLAN/2 Networks

Recent advances on wireless technology are enabling the design and deployment of multiservice wireless networks. In order to be able to meet the QoS requirements of the various applications, it is essential to deploy QoS provisioning mechanisms. In this paper, we present a QoS framework to support various types of services in a wireless networking environment. Under this QoS framework, we propose various resource request mechanisms. We carry out a comparative study of the proposed schemes. Our simulation results show the effectiveness of the mechanisms when supporting different services, such as video, voice, best-effort and background traffic. Francisco M. Delicado This author received his M.Sc. degree in Physics (Electronics and Computer Science) from the University Complutense of Madrid, Madrid, Spain in 1995. He is currently a Ph.D. degree student in the Department of Computer Engineering at the University of Castilla-La Mancha. His research interests include high-performance networks, specially wireless LAN, QoS over WLAN, video compression, video transmission and error-resilient protocol architectures. Pedro Cuenca This author received his M.Sc. degree in Physics (Electronics and Computer Science, award extraordinary) from the University of Valencia in 1994. He got his Ph.D. degree in Computer Engineering in 1999 from the Polytechnic University of Valencia, Spain. In 1995 he joined the Department de Computer Engineering at the University of Castilla-La Mancha. He is currently an Associate Professor of Communications and Computer Networks. He has also been a visiting researcher at The Nottingham Trent University, Nottingham (England) and at the Multimedia Communications Research Laboratory, University of Ottawa (Canada). His research topics are centered in the area of high-performance networks, wireless LAN, video compression, QoS video transmission and error-resilient protocol architectures. He has served in the organization of International Conferences as Session Chair. He has been reviewer for several Journals and for several International Conferences. He is a member of the IFIP 6.8 Working Group and a member of the IEEE. Luis Orozco-Barbosa This author received the B.Sc. degree in electrical and computer engineering from Universidad Autonoma Metropolitana, Mexico, in 1979, the Diplome d'Etudes Approfondies from ENSIMAG, France, in 1984 and the Doctorat de l'Universite from Universite Pierre et Marie Curie, France, in 1987, both in computer science. From 1991 to 2002, he was a Faculty Member of Computer Engineering at the School of Information Technology and Engineering (SITE), University of Ottawa, Canada. In 2002, he joined the Department of Computer Engineering at Universidad de Castilla La Mancha (SPAIN) where he is currently Director of the Albacete Research Institute of Informatics. He has published over 180 papers in international Journals and Conferences on computer networks and performance evaluation. His current research interests include Internet protocols, video communications, wireless networks, traffic modeling and performance evaluation. He is a member of the IEEE. Antonio Garrido This author received the degree in physics (electronics and computer science) and the Ph.D. degrees from the University of Granada, Spain, in 1986 and University of Valencia, Spain, in 1991, respectively. In 1986, he joined the Department of Computer Engineering at the University of Castilla-La Mancha, where he is currently a Full Professor of Computer Architecture and Technology and Dean of the EscuelaPolitecnica Superior de Albacete (School of Computer Engineering). His research interests include high-performance networks, telemedicine, video compression, and video transmission. He has published over 40 papers in international journals conferences on performance evaluation of parallel computer and communications systems and compression and transmission in high-speed networks. He has led several research projects in telemedicine, computer networks and advanced computer system architectures.     

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.