New CMOS Class AB Transmitter for 10 Gb/s Serial Links

This paper presents a new fully differential CMOS class AB transmitter for 10 Gb/s serial links. The transmitter consists of a fully differential multiplexer, a rail-to-rail configured pre-amplification stage, and a push-pull output stage. The multiplexer achieves a high multiplexing speed by using modified pseudo-NMOS logic where pull-up networks are replaced with self-biased active inductors. The rail-to-rail configured pre-amplification stage with active inductors amplifies the signals from the multiplexer. The fully differential output current is generated by a class AB output stage operated in a push-pull mode. High data rates of the transmitter are obtained by ensuring that the transistors in both the pre-amplification and output stages are always in saturation and the voltage swing of all critical nodes is small. The fully differential configuration of the transmitter effectively suppresses common-mode disturbances, particularly those coupled from the power and ground rails, the electro-magnetic interference exerted from channels to neighboring devices is also minimized. The transmitter minimizes switching noise by drawing a constant current from the supply voltage. The transmitter has been implemented in TSMC 0.18 μm 1.8 V 6-metal CMOS technology and analyzed using Spectre from Cadence Design Systems with BSIM3.3 device models. Simulation results demonstrate that the transmitter provides a 5 mA peak-to-peak differential output current with 100 ps eye-width and >5 mA eye-height at 10 Gb/s. The transmitter consumes 18 mW with a total transistor area of 100 μm² approximately. Jean Jiang received the B.Eng. degree in Electrical Engineering from Wuhan University of Technology, Wuhan, China in 1995, and the M.A.Sc. degree in Electrical and Computer Engineering from Ryerson University, Toronto, Ontario, Canada in 2004. From 1999 to 2001, she worked for Ericsson Global IT Services where she was a technical staff to maintain computer networks. From 2002 to 2004, she was a research assistant and a M.A.Sc. student with the Microsystem Research Laboratory in the Department of Electrical and Computer Engineering at Ryerson University. She is now with Intel Corp., CA. as an IC design engineer. Her research interests are in analog CMOS circuit design for high-speed data communications. Jean Jiang was awarded the Ontario Graduate Scholarship in 2003–2005 for academic excellence. Fei Yuan received the B.Eng. degree in electrical engineering from Shandong University, Jinan, China in 1985, the M.A.Sc. degree in chemical engineering and Ph.D. degree in electrical engineering from University of Waterloo, Waterloo, Ontario, Canada in 1995 and 1999, respectively. During 1985–1989, he was a Lecturer in the Department of Electrical Engineering, Changzhou Institute of Technology, Jiangsu, China. In 1989 he was a Visiting Professor at Humber College of Applied Arts and Technology, Toronto, Ontario, Canada, and Lambton College of Applied Arts and Technology, Sarnia, Ontario, Canada. He was with Paton Controls Limited, Sarnia, Ontario, Canada as a Controls Engineer during 1989–1994. Since 1999 he has been with the Department of Electrical and Computer Engineering, Ryerson University, Toronto, Ontario, Canada, where he is currently an Associate Professor and the Associate Chair for Undergraduate Studies and Faculty Affairs. He is the co-author of the book Computer Methods for Analysis of Mixed-Mode Switching Circuits (Springer-Verlag, 2004, with Ajoy Opal). Dr. Yuan received the Ryerson Research Chair award from Ryerson University in Jan. 2005, the Research Excellence Award from the Faculty of Engineering and Applied Science of Ryerson University in 2004, the post-graduate scholarship from Natural Science and Engineering Research Council of Canada during 1997–1998, and the Teaching Excellence Award from Changzhou Institute of Technology in 1988. Dr. Yuan is a senior member of IEEE and a registered professional engineer in the province of Ontario, Canada.     

A New CMOS Current-Mode Multiplexer for l0 Gbps Serial Links

This paper presents an in-depth study of the pros and cons of voltage-mode multiplexers for Gbps serial links and exploits the advantages of multiplexing in current domain. In addition, it proposes a new fully differential CMOS current-mode multiplexer where a high multiplexing speed is achieved by multiplexing at a low-impedance node. Multiplexing speed is further improved by inductive shunt peaking with active inductors. The differential configuration of the multiplexer minimizes the effect of common-mode disturbances, particularly those coupled from the power and ground rails. The flow of the output currents in the opposite directions minimizes the effect of electro-magnetic interference from channels, making the multiplexer particularly attractive for high-speed data transmission over long interconnects and printed-circuit-board (PCB) traces. The proposed multiplexer draws a constant current from the supply voltage, thereby minimizing both switching noise and noise injected to the substrate. A fully differential CMOS current-mode 8-to-l multiplexer has been implemented in TSMC’s 1.8 V 0.18 μm CMOS technology and analyzed using Spectre from Cadence Design Systems with BSIM3.3v device models. Simulation results demonstrate that the multiplexer offers sufficiently large eye-opening when multiplexed at 10 Gbps.Jean Jiang received the B.Eng. degree in Electrical Engineering from Wuhan University of Technology, Wuhan, China in 1995. From 1999 to 2001, she worked for Ericsson Global IT Services where she was a technical staff to maintain computer networks. Since 2002, she has been a research assistant with the System-on-Chip research lab of Ryerson University. She is currently a M.A.Sc candidate under the supervision of Dr. Fei Yuan in the Department of Electrical and Computer Engineering, Ryerson University, Toronto, Canada. Her research interests are in analog CMOS circuit design for high-speed data communications. She was awarded the Ontario Graduate Scholarship (OGS) in 2003–2005 for academic excellence.Fei Yuan received the B.Eng. degree in electrical engineering from Shandong University, Jinan, China in 1985, the MASc. degree in chemical engineering and PhD. degree in electrical engineering from University of Waterloo, Waterloo, Ontario, Canada in 1995 and 1999, respectively.During 1985–1989, he was a Lecturer in the Department of Electrical Engineering, Changzhou Institute of Technology, Jiangsu, China. In 1989 he was a Visiting Professor at Humber College of Applied Arts and Technology, Toronto, Canada. During 1989–1994, he worked for Paton Controls Limited, Sarnia, Ontario, Canada as a Controls Engineer. Since July 1999 he has been with the Department of Electrical and Computer Engineering, Ryerson University, Toronto, Ontario, Canada, where he is currently an Associate Professor and the Associate Chair for Undergraduate Studies and Faculty Affairs. He is the co-author of the book “Computer Methods for Analysis of Mixed-Mode Switching Circuits” (Kluwer Academic Publishers, 2004, with Ajoy Opal). Dr. Yuan received an “Excellence of Teaching” award from Changzhou Institute of Technology in 1988, a post-graduate scholarship from Natural Science and Engineering Research Council (NSERC) of Canada during 1997–1998. He is a senior member of IEEE and a registered professional engineer in the province of Ontario, Canada.     

A New Differential CMOS Current-Mode Preamplifier for GBps Data Communications

This paper presents a new low-voltage fully differential CMOS current-mode preamplifier for GBps data communications. The number of transistors between the power and ground rails is only two so that the minimum supply voltage is one threshold voltage plus one pinch-off voltage. The preamplifier is a balanced two-stage configuration such that the effect of bias-dependent mismatches is minimized. A new inductive series-peaking technique is introduced to increase the bandwidth by utilizing the resonance characteristics of LC networks. In addition, a new negative differential current feedback technique is proposed to boost the bandwidth and to reduce the value of peaking inductors. The preamplifier has been implemented in TSMC 0.18 μm, 1.8 V, 6-metal mixed-mode CMOS technology and analyzed using Spectre from Cadence Design Systems with BSIM3v3 device models. For an optical front-end with a 0.3 pF photodiode capacitance, simulation results demonstrate that the preamplifier has bandwidth of 3.5 GHz and provides a transimpedance gain of 66 dBΩ. The total chip area is approximately 1 mm² and the DC power consumption is about 85 mW. Bendong Sun received the B.Eng. degree in electrical engineering from Shanghai Jiaotong University, Shanghai, China, in1992, and the MASc degree in electrical and computer engineering from Ryerson University, Toronto, Ontario, Canada, in 2003. He is currently working towards the Ph.D. degree in electrical and computer engineering at University of Waterloo, Waterloo, Ontario, Canada. During 1992 through 1998 he was a Design Engineer at China Electronics Engineering Design Institute, Beijing, China. From 1998 to 2000 he worked for Bently Nevada Corporation, a GE Power Systems business, as a System Engineer. Since 2001, he has been a Research Assistant with the System-on-Chip Laboratory at Ryerson University. His research interests include design of analog and mixed-signal integrated circuits for high-speed data communications. Fei Yuan received the B.Eng. degree in electrical engineering from Shandong University, Jinan, China in 1985, the MASc degree in chemical engineering and PhD degree in electrical engineering from University of Waterloo, Waterloo, Ontario, Canada in 1995 and 1999, respectively. During 1985–1989, he was a Lecturer in the Department of Electrical Engineering, Changzhou Institute of Technology, Jiangsu, China. In 1989 he was a Visiting Professor at Humber College of Applied Arts and Technology, Toronto, Canada. During 1989–1994, he worked for Paton Controls Limited, Sarnia, Ontario, Canada as a Controls Engineer. Since July 1999 he has been with the Department of Electrical and Computer Engineering, Ryerson University, Toronto, Ontario, Canada, where he is currently an Associate Professor and the Associate Chair for Undergraduate Studies and Faculty Affairs. He is the co-author of the book “Computer Methods for Analysis of Mixed-Mode Switching Circuits” (Kluwer Academic Publishers, 2004, with Ajoy Opal). Dr. Yuan received an “Excellence of Teaching" award from Changzhou Institute of Technology in 1988, a post-graduate scholarship from Natural Science and Engineering Research Council (NSERC) of Canada during 1997–1998. He is a senior member of IEEE and a registered professional engineer in the province of Ontario, Canada. Ajoy Opal (S'86-M'88) received the B. Tech degree from Indian Institute of Technology, New Delhi, India in 1981, and the MASc and PhD degrees from University of Waterloo, Waterloo, Ontario, Canada in 1984 and 1987, respectively. During 1989–92 he worked for Bell-Northern Research in the area of analog circuit simulation. He joined the Department of Electrical and Computer Engineering, University of Waterloo in 1992 and currently a Full Professor. Dr. Opal works in the area of simulation of analog and mixed digital-analog circuits, such as, switched capacitor, switched current, oversampled sigma-delta modulators. Other interests include circuit theory and filter design.     

A Novel Approach to Cell Coverage Area Determination for FDMA–CDMA Systems

There is no theoretical time or frequency restrictions on capacity in DS-CDMA systems. In these systems, the signal to interference ratio (SIR) has a major effect on capacity. Since an increase in the user SIR at the base station (BS) leads to higher capacity, transmission power control is employed. The nonuniform distribution of users in the network causes different quality of service (QOS) in distinct regions, therefore network resources may not be utilized properly. A dynamic distribution algorithm can be employed to balance the QOS delivered in different regions of the network. In this paper, a novel dynamic distribution algorithm is introduced. The proposed algorithm deactivates certain users when the network encounters an overload. By applying this policy, the required SIR can be maintained for the remaining users. F. Hendessi received a B.Sc. degree from Baluchestan University, Iran in 1986, and an M.Sc. degree from Isfahan University of Technology, Iran in 1988, both in Electrical Engineering. In 1993 he received a Ph.D. in Electrical Engineering from Carleton University, Ottawa, Ontario, Canada. He is currently an Assistant Professor in the Department of Electrical Engineering at Isfahan University of Technology. A. Ghayoori received B.Sc. and M.Sc. degrees in Electrical Engineering from Isfahan University of Technology, Isfahan, Iran, in 2001 and 2003, respectively. He is currently a Research Engineer with the ICT research center at IUT. T. A. Gulliver received a 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 Realistic Timing Test Model and Its Applications in High-Speed Interconnect Devices

This paper extends the timing test model in [5] to be more realistic by including the effects of the test fixtures between a device under test and a tester. The paper enables analyzing the trade-offs that arise between the predicted yield and the required overall test environment timing accuracy (OTETA) which involves the tester overall timing accuracy (OTA) and the test fixtures' impacts. We specifically focus on the application of the extended model to predict the test yield of standard high-speed interconnects, such as PCI Express, Parallel/Serial RapidIO, and HyperTransport. The extended model reveals that achieving an actual yield of 80% with a test escape of 300 DPM (Defects Per Million) requires an equivalent OTETA that is about half the acceptable absolute limit of the tested parameter. Baosheng Wang received his B.S. degree from Beijing University of Aeronautics and Astronautics (BUAA), Beijing, P.R. China, in 1997 and M.S. degree from Precision Instrument & Mechanical Engineering from the Tsinghua University, Beijing, P. R. China in 2000. In 2005, he received his Ph.D. degree in Electrical Engineering from the University of British Columbia (UBC), Vancouver, BC, Canada. During his Master study, he was doing MEMS, Micro Sensors and Digital Signal processing. From 2000 to 2001, he worked in Beijing Gaohong Telecommunications Company as a hardware engineer in ATM technology. Currently, he is a Design-for-Test (DFT) engineer at ATI Technologies Inc., Markham, Ontario, Canada. He publishes widely at international conferences and journals. His primary research interests are time-driven or timing-oriented testing methodologies for System on-a-Chip (SoC). These fields include test time reduction for SRAMs, accelerated reliability test for non-volatile memories, yield analysis for SoC timing tests, SoC path delay timing characterization and embedded timing measurements. Andy Kuo is currently a Ph.D student of System on a Chip (SoC) Research Lab at the Department of Electrical and Computer Engineering, University of British Columbia. He received his M.A.Sc. and B.A.Sc in electrical and computer engineering from University of British Columbia and University of Toronto in 2004 and 2002 respectively. His research interests include high-speed signal integrity issues, jitter measurement, serial communications. Touraj Farahmand received the B.Sc. degree in Electrical Engineering from Esfahan University of Technology, Esfahan, Iran in 1989 and the M.Sc. in Control Engineering from Sharif university of Technology, Tehran, Iran in 1992. After graduation, he joined the Electrical and Computer Research center of Esfahan University of Technology where he was involved in the DSP algorithm development and design and implementation of the control and automation systems. Since October 2001, he has been working in the area of high-speed signal timing measurement at SoC (System-on-a-Chip) lab of UBC (University of British Columbia) as a research engineer. His research interests are signal processing, jitter measurement, serial communication and control. André Ivanov is Professor in the Department of Electrical and Computer Engineering, at the University of British Columbia. Prior to joining UBC in 1989, he received his B.Eng. (Hon.), M. Eng., and Ph.D. degrees in Electrical Engineering from McGill University. In 1995–96, he spent a sabbatical leave at PMC-Sierra, Vancouver, BC. He has held invited Professor positions at the University of Montpellier II, the University of Bordeaux I, and Edith Cowan University, in Perth, Australia. His primary research interests lie in the area of integrated circuit testing, design for testability and built-in self-test, for digital, analog and mixed-signal circuits, and systems on a chip (SoCs). He has published widely in these areas and holds several patents in IC design and test. Besides testing, Ivanov has interests in the design and design methodologies of large and complex integrated circuits and SoCs. Dr. Ivanov has served and continues to serve on numerous national and international steering, program, and/or organization committees in various capacities. Recently, he was the Program Chair of the 2002 VLSI Test Symposium (VTS'02) and the General Chair for VTS'03 and VTS'04. In 2001, Ivanov co-founded Vector 12, a semiconductor IP company. He has published over 100 papers in conference and journals and holds 4 US patents. Ivanov serves on the Editorial Board of the IEEE Design and Test Magazine, and Kluwer's Journal of Electronic Testing: Theory and Applications. Ivanov is currently the Chair of the IEEE Computer Society's Test Technology Technical Council (TTTC). He is a Golden Core Member of the IEEE Computer Society, a Senior Member of the IEEE, a Fellow of the British Columbia Advanced Systems Institute and a Professional Engineer of British Columbia. Yong Cho received the B.S. degree from Kyung Pook National Unviersity, Korea, in 1981 and the M.S. degree from in electrical and computer engineering from the University of South Carolina, Columbia, S.C., in 1988 and the Ph.D. degree in electrical engineering and applied physics from Case Western Reserve University, Cleveland, OH, in 1992. He is currently a Professor with the Department of Electronics Engineering, Konkuk University, Seoul, Korea. His recent research interests include SoC Design and Verification, H/W and S/W co-design, and embedded programming on SoC. Sassan Tabatabaei received his PHD in Electrical Engineering from the University of British Columbia, Vancouver, Canada in 2000. Since then, he has held several senior technical positions at Vector12 Corp, Guide Technology, and Virage Logic. His professional and research interests include mixed-signal design and test, and signal integrity and jitter test methodologies for high-speed circuits and multi-Gbps serial interfaces. He has published several papers and holds a US patent in the area of timing and jitter measurement. Currently, he holds the position of the director for embedded test at Virage Logic Corporation.     

Signal threshold adaptation for vertical handoff in heterogeneous wireless networks

The convergence of heterogeneous wireless access technologies has been envisioned to characterize the next generation wireless networks. In such converged systems, the seamless and efficient handoff between different access technologies (vertical handoff) is essential and remains a challenging problem. The heterogeneous co-existence of access technologies with largely different characteristics results in handoff asymmetry that differs from the traditional intra-network handoff (horizontal handoff) problem. In the case where one network is preferred, the vertical handoff decision should be carefully executed, based on the wireless channel state, network layer characteristics, as well as application requirements. In this paper, we study the performance of vertical handoff using the integration of 3G cellular and wireless local area networks as an example. In particular, we investigate the effect of an application-based signal strength threshold on an adaptive preferred-network lifetime-based handoff strategy, in terms of the signalling load, available bandwidth, and packet delay for an inter-network roaming mobile. We present an analytical framework to evaluate the converged system performance, which is validated by computer simulation. We show how the proposed analytical model can be used to provide design guidelines for the optimization of vertical handoff in the next generation integrated wireless networks. This article is the extended version of a paper presented in IFIP Networking 2005 Ahmed H. Zahran is a Ph.D. candidate at the Department of Electrical and Computer Engineering, University of Toronto. He received both his M.Sc. and B.Sc. in Electrical Engineering from Electronics and Electrical Communication Department in the Faculty of Engineering, Cairo University in 2002 and 2000 respectively, where he was holding teaching and research positions. Since September 2003, he has been working as a research assistant in the Department of Electrical and Computer Engineering, University of Toronto under the supervision of Professor Ben Liang. His research interest is wireless communication and networking with an emphasis on the design and analysis of networking protocols and algorithms. Ben Liang received honors simultaneous B.Sc. (valedictorian) and M.Sc. degrees in Electrical Engineering from Polytechnic University in Brooklyn, New York, in 1997 and the PhD degree in Electrical Engineering with Computer Science minor from Cornell University in Ithaca, New York, in 2001. In the 2001–2002 academic year, he was a visiting lecturer and post-doctoral research associate at Cornell University. He joined the Department of Electrical and Computer Engineering at the University of Toronto as an Assistant Professor in 2002. His current research interests are in the areas of mobile networking and wireless multimedia systems. He is a member of Tau Beta Pi, IEEE, and ACM and serves on the organization and technical program committees of a number of major conferences each year. Aladdin Saleh earned his Ph.D. degree in Electrical Engineering from London University, England. Since March 1998, Dr. Saleh has been working in the Wireless Technology Department of Bell Canada, the largest service provider of wireless, wire-line, and Internet in Canada. He worked as a senior application architect in the wireless data group working on several projects among them the wireless application protocol (WAP) and the location-based services. Later, he led the work on several key projects in the broadband wireless network access planning group including planning of the IEEE 802.16/ Wimax, the IEEE 802.11/ WiFi, and the integration of these technologies with the 3G cellular network including Mobile IP (MIP) deployment. Dr. Saleh also holds the position of Adjunct Full Professor at the Department of Electrical and Computer Engineering of Waterloo University, Canada since January 2004. He is currently conducting several joint research projects with the University of Waterloo and the University of Toronto on IEEE 802.16-Wimax, MIMO technology, interworking of IEEE 802.11 WLAN and 3G cellular networks, and next generation wireless networks. Prior to joining Bell Canada, Dr. Saleh worked as a faculty member at different universities and was Dean and Chairman of Department for several years. Dr. Saleh is a Fellow of IEE and a Senior Member of IEEE.     

Dropping Rate Reduction in Hybrid WLAN/Cellular Systems by Mobile Ad Hoc Relaying

Future mobile handsets will often be multi-mode, containing both wireless LAN (WLAN) and cellular air interfaces. When such a device is within a WLAN it can be served by the WLAN resources. As it moves out of the WLAN coverage area, it has to be served by the cellular system. Therefore, handoffs are necessary between the WLAN and the cellular system. In loosely coupled WLAN/Cellular systems the system administrator of the WLAN is different from the cellular one. Therefore, in these situations, reducing the dropping probability based on classical methods, such as using some reserved guard channels, is difficult. In this paper, we propose to use ad hoc relaying during the vertical handoff process in a hybrid WLAN/Cellular system. The method that we propose in this paper improves the dropping probability regardless of the number of reserved channels. Therefore, this method could be employed in loosely coupled hybrid systems. Both analytical reasoning and simulation results support the effectiveness of the proposed method. Pejman Khadivi received the BS and MS degrees in computer engineering (Hardware and Computer Systems Architecture) in 1998 and 2000, respectively from Isfahan University of Technology, where he is currently working toward his Ph.D. During the 2003/2004 academic year, he was a Visiting Researcher with the Electrical and Computer Engineering Department, McMaster University, ON, Canada. Different aspects of computer architecture and networking are Mr. Khadivi’s research interests specially, adhoc networks, QoS routing and seamless handoff in hybrid mobile networks. Shadrokh Samavi received the B.S. degrees in industrial technology and electrical engineering from the California State University, Fresno, in 1980 and 1982, respectively, the M.S. degree from the University of Memphis, Memphis, TN, in 1985, and the Ph.D. degree in electrical engineering from Mississippi State University, Mississippi State, in 1989. In 1995, he joined the Electrical and Computer Engineering Department, Isfahan University of Technology, Isfahan, Iran, where he was an Associative Professor. During the 2002/2003 academic year, he was a Visiting Professor with the Electrical and Computer Engineering Department, McMaster University, Hamilton, ON, Canada. His current research interests are implementation and optimization of image-processing algorithms and area-performance tradeoffs in computational circuits. Dr. Samavi is a Registered Professional Engineer (P.E.), USA, and is a member of Eta Kappa Nu, Tau Beta Pi, and the National Association of Industrial Technologists (NAIT). Hossein Saidi received the B.S. and M.S. degrees in electrical engineering (Electronics and communication Eng.) from Isfahan University of Technology (IUT), in 1986 and 1989, respectively, and the Ph.D. degree in electrical engineering from the Washington University in St. Louis, MO. in 1994.From 1994 to 1995, he was a research associates at Washington Univ. St. Louis, and in 1995 he joined the Electrical and Computer Engineering of IUT, where he is an Associate Professor. His Research interest includes ATM, high speed networking, QoS guarantees, routing, algorithms and information theory. Terence D. Todd received the B.A.Sc, M.A.Sc and Ph.D degrees in Electrical Engineering from the University of Waterloo, Waterloo, Ontario, Canada. While at Waterloo he spent 3 years as a Research Associate with the Computer Communications Networks Group (CCNG). He is currently a Professor of Electrical and Computer Engineering at McMaster University in Hamilton, Ontario, Canada.Professor Todd spent 1991 on research leave in the Distributed Systems Research Department at AT&T Bell Laboratories in Murray Hill, NJ. He also spent 1998 on research leave at The Olivetti and Oracle Research Laboratory in Cambridge, England. While at ORL he worked on the piconet project which was an early embedded wireless network testbed.Dr. Todd’s research interests include metropolitan/local area networks, wireless communications and the performance analysis of computer communication networks and systems. He currently holds the NSERC/RIM/CITO Industrial Research Chair on Pico-Cellular Wireless Internet Access Networks. Dr. Todd is a Professional Engineer in the province of Ontario and a member of the IEEE. Dongmei Zhao received the Ph.D degree in Electrical and Computer Engineering from the University of Waterloo, Waterloo, Ontario, Canada in June 2002. Since July 2002 she has been with the Department of Electrical and Computer Engineering, McMaster University, Hamilton, Ontario, Canada where she is an assistant professor. Dr. Zhao’s research interests include modeling and performance analysis, quality-of-service provisioning, access control and admission control in wireless cellular networks and integrated cellular and ad hoc networks. Dr. Zhao is a member of the IEEE.     

Run-Time Reconfigurable Systems for Digital Signal Processing Applications: A Survey

Todays digital signal processing (DSP) applications use computationally complex and/or adaptive algorithms and have stringent requirements in terms of speed, size, cost, power consumption, and throughput. Efficient hardware implementation techniques should be employed to meet the requirements of these applications. Run-Time Reconfiguration (RTR) is a promising technique for reducing the hardware required for implementing DSP systems as well as improving the performance, speed and power consumption of these systems. In this survey, we explain different issues in run-time reconfigurable systems and list the implemented systems which support run-time reconfiguration. We also describe different applications of run-time reconfiguration and discuss the improvements achieved by applying run-time reconfiguration.Alireza Shoa received his B.Sc degree in Electrical Engineering from Sharif University of Technology, Tehran, Iran in 2001 and M.A.Sc degree in Electrical Engineering from McMaster University, Hamilton, Canada in 2003. Currently, he is a PhD candidate in Electrical Engineering at McMaster University. His research interests include VLSI circuits for signal processing and communication applications and image and video processing.Shahram Shirani received his B.S. in Electrical Engineering from Isfahan University of Technology, Isfahan, Iran, and M.Sc. in Biomedical Engineering from Amirkabir University of Technology, Tehran, Iran, and Ph.D. in Electrical Engineering from University of British Columbia, Vancouver, Canada, in 1989, 1994 and 2000 respectively. Since 2000 he has been with the department of Electrical and Computer Engineering, McMaster University, where he is an assistant professor. His research interests include image and video compression, multimedia communications, and ultrasonic imaging. He is a member of technical committee of IEEE International Conference on Image Processing (ICIP). He is a licensed professional engineer and a member of Institute of Electrical and Electronics Engineers (IEEE).     

Admission control with load balancing in IEEE 802.11-based ESS mesh networks

In this paper we study connection admission control (CAC) in IEEE 802.11-based ESS mesh networks. An analytical model is developed for studying the effects of CAC on mesh network capacity. A distributed CAC scheme is proposed, which incorporates load balancing when selecting a mesh path for new connections. Our results show that connection level performance, including both average number of connections and connection blocking probability, can be greatly improved using the proposed mechanism compared to other admission control schemes. Dongmei Zhao received the Ph.D. degree in Electrical and Computer Engineering from the University of Waterloo, Waterloo, Ontario, Canada in June 2002. Since July 2002 she has been with the Department of Electrical and Computer Engineering, McMaster University, Hamilton, Ontario, Canada where she is an assistant professor. Dr. Zhao’s research interests include modeling and performance analysis, quality-of-service provisioning, access control and admission control in wireless networks. Dr. Zhao is a member of the IEEE. Jun Zou received his B. Eng. and M. Eng. Degrees from Tianjin University, China in 1999 and 2002, respectively. He worked at Siemens Communication Networks Ltd., Beijing from 2002 to 2004. Currently, he is a PhD. student at McMaster University, Canada. His research interests include wireless networking, routing protocols, architecture of next generation networks and network security. Terence D. Todd received the B.A.Sc., M.A.Sc. and Ph.D. degrees in Electrical Engineering from the University of Waterloo, Waterloo, Ontario, Canada. While at Waterloo Dr. Todd spent 3 years as a Research Associate with the Computer Communications Networks Group (CCNG). He is currently a Professor of Electrical and Computer Engineering at McMaster University in Hamilton, Ontario, Canada. At McMaster he has been the Principal Investigator on a number of projects in the optical networks and wireless networking areas. Professor Todd spent 1991 on research leave in the Distributed Systems Research Department at AT&T Bell Laboratories in Murray Hill, NJ. He also spent January-December 1998 on research leave at The Olivetti and Oracle Research Laboratory in Cambridge, England. While at ORL he worked on the piconet project which was an early embedded wireless network testbed. Dr. Todd’s research interests include metropolitan/local area networks, wireless communications and the performance analysis of computer communication networks and systems. Dr. Todd is a past Editor of the IEEE/ACM Transactions on Networking and currently holds the NSERC/RIM/CITO Chair on Pico-Cellular Wireless Internet Access Networks Dr. Todd is a Professional Engineer in the province of Ontario and a member of the IEEE.     

Statistical multiplexing, admission region, and contention window optimization in multiclass wireless LANs

This paper presents an analytical model for evaluating the statistical multiplexing effect, admission region, and contention window design in multiclass wireless local area networks (WLANs). We consider distributed medium access control (MAC) which provisions service differentiation by assigning different contention windows to different classes. Mobile nodes belonging to different classes may have heterogeneous traffic arrival processes with different quality of service (QoS) requirements. With bursty input traffic, e.g. on/off sources, our analysis shows that the WLAN admission region under the QoS constraint can be significantly improved, when the statistical multiplexing effect is taken into account. We also analyze the MAC resource sharing between the short-range dependent (SRD) on/off sources and the long-range dependent (LRD) fractional Brownian motion (FBM) traffic, where the impact of the Hurst parameter on the admission region is investigated. Moveover, we demonstrate that the proper selection of contention windows plays an important role in improving the WLAN’s QoS capability, while the optimal contention window for each class and the maximum admission region can be jointly solved in our analytical model. The analysis accuracy and the resource utilization improvement from statistical multiplexing gain and contention window optimization are demonstrated by extensive numerical results. Yu Cheng received the B.E. and M.E. degrees in Electrical Engineering from Tsinghua University, Beijing, China, in 1995 and 1998, respectively, and the Ph.D. degree in Electrical and Computer Engineering from the University of Waterloo, Waterloo, Ontario, Canada, in 2003. From September 2004 to July 2006, he was a postdoctoral research fellow in the Department of Electrical and Computer Engineering, University of Toronto, Ontario, Canada. Since August 2006, he has been with the Department of Electrical and Computer Engineering, Illinois Institute of Technology, Chicago, Illinois, USA, as an Assistant Professor. His research interests include service and application oriented networking, autonomic network management, Internet performance analysis, resource allocation, wireless networks, and wireless/wireline interworking. He received a Postdoctoral Fellowship Award from the Natural Sciences and Engineering Research Council of Canada (NSERC) in 2004. Xinhua Ling received the B. Eng. degree in Radio Engineering from Southeast University, Nanjing, China in 1993 and the M. Eng. degree in Electrical Engineering from the National University of Singapore, Singapore in 2001. He is currently pursuing the Ph.D. degree in the Department of Electrical and Computer Engineering at the University of Waterloo, Ontario, Canada. From 1993 to 1998, he was an R&D Engineer in Beijing Institute of Radio Measurement, China. From February 2001 to September 2002, he was with the Centre for Wireless Communications (currently Institute for Infocom Research), Singapore, as a Senior R&D Engineer, developing the protocol stack for UE in the UMTS system. His general research interests are in the areas of cellular, WLAN, WPAN, mesh and ad hoc networks and their internetworking, focusing on protocol design and performance analysis. Lin X. Cai received the B.Sc. degree in computer science from Nanjing University of Science and Technology, Nanjing, China, in 1996 and the MASc. degree in electrical and computer engineering from the University of Waterloo, Waterloo, Canada, in 2005. She is currently working toward the Ph.D. degree in the same field at the University of Waterloo. Her current research interests include network performance analysis and protocol design for multimedia applications over wireless networks. Wei Song received the B.S. degree in electrical engineering from Hebei University, China, in 1998 and the M.S. degree in computer science from Beijing University of Posts and Telecommunications, China, in 2001. She is currently working toward the Ph.D. degree at the Department of Electrical and Computer Engineering, University of Waterloo, Canada. Her current research interests include resource allocation and quality-of-service (QoS) provisioning for the integrated cellular networks and wireless local area networks (WLANs). Weihua Zhuang received the Ph.D. degree in electrical engineering from the University of New Brunswick, Canada. Since October 1993, she has been with the Department of Electrical and Computer Engineering, University of Waterloo, Canada, where she is a Professor. Dr. Zhuang is a co-author of the textbook Wireless Communications and Networking (Prentice Hall, 2003). Her current research interests include multimedia wireless communications, wireless networks, and radio positioning. She received the Outstanding Performance Award in 2005 and 2006 from the University of Waterloo and the Premier’s Research Excellence Award in 2001 from the Ontario Government for demonstrated excellence of scientific and academic contributions. She is the Editor-in-Chief of IEEE Transactions on Vehicular Technology and an Editor of IEEE Transactions on Wireless Communications. Xuemin (Sherman) Shen received the B.Sc.(1982) degree from Dalian Maritime University (China) and the M.Sc. (1987) and Ph.D. degrees (1990) from Rutgers University, New Jersey (USA), all in electrical engineering. He is a Professor and the Associate Chair for Graduate Studies, Department of Electrical and Computer Engineering, University of Waterloo, Canada. His research focuses on mobility and resource management in interconnected wireless/wired networks, UWB wireless communications systems, wireless security, and ad hoc and sensor networks. He is a co-author of three books, and has published more than 300 papers and book chapters in wireless communications and networks, control and filtering. Dr. Shen serves as the Technical Program Committee Chair for IEEE Globecom’07, General Co-Chair for Chinacom’07 and QShine’06, the Founding Chair for IEEE Communications Society Technical Committee on P2P Communications and Networking. He also serves as a Founding Area Editor for IEEE Transactions on Wireless Communications; Associate Editor for IEEE Transactions on Vehicular Technology; KICS/IEEE Journal of Communications and Networks; Computer Networks (Elsevier); ACM/Wireless Networks; and Wireless Communications and Mobile Computing (John Wiley), etc. He has also served as Guest Editor for IEEE JSAC, IEEE Wireless Communications, and IEEE Communications Magazine. Dr. Shen received the Excellent Graduate Supervision Award in 2006, and the Outstanding Performance Award in 2004 from the University of Waterloo, the Premier’s Research Excellence Award in 2003 from the Province of Ontario, Canada, and the Distinguished Performance Award in 2002 from the Faculty of Engineering, University of Waterloo. Dr. Shen is a registered Professional Engineer of Ontario, Canada. Alberto Leon-Garcia received the B.S., M.S., and Ph.D. degrees in electrical engineering from the University of Southern California, in 1973, 1974, and 1976 respectively. He is a Full Professor in the Department of Electrical and Computer Engineering, University of Toronto, ON, Canada, and he currently holds the Nortel Institute Chair in Network Architecture and Services. In 1999 he became an IEEE fellow for “For contributions to multiplexing and switching of integrated services traffic”. Dr. Leon-Garcia was Editor for Voice/Data Networks for the IEEE Transactions on Communications from 1983 to 1988 and Editor for the IEEE Information Theory Newsletter from 1982 to 1984. He was Guest Editor of the September 1986 Special Issue on Performance Evaluation of Communications Networks of the IEEE Selected Areas on Communications. He is also author of the textbooks Probability and Random Processes for Electrical Engineering (Reading, MA: Addison-Wesley), and Communication Networks: Fundamental Concepts and Key Architectures (McGraw-Hill), co-authored with Dr. Indra Widjaja.     

Improvements in Biasing and Compensation of CMOS Opamps

In this paper, we present modifications to the constant-g_m bias circuit and Miller-lead compensation of operational amplifiers which eliminate or minimize some of their shortcomings. First, we demonstrate how parasitic pad capacitance can cause instability in the constant-g_m bias circuit, and show that the transconductance is constant only for specific bias conditions. Next, we suggest a new circuit topology that requires 75% less compensation capacitance to achieve stability. We also discuss problems with Miller-lead compensation that arise from temperature, process, and load variations. Finally, we present a new biasing technique to correct these problems, and, through simulation, demonstrate a 40^∘ improvement in phase margin over load current variations.Sean Nicolson received the B.A.Sc. degree in 2000 from Simon Fraser University, Vancouver, Canada, and the M.A.Sc. degree in 2003 from the University of Toronto, Toronto, Canada. In 2001, he was an design engineer for NeuroStream Technologies, Inc., where he developed implantable electronic systems.Currently, he is working on his PhD degree in the Edward S. Rogers Senior Department of Electrical and Computer Engineering, University of Toronto. His research interests include integrated circuits for biomedical applications, RF communication systems, and millimeter-wave circuits.Khoman Phang (M’00) received the B.A.Sc., M.A.Sc., and Ph.D. degrees in 1990, 1992, and 2001 respectively from the University of Toronto, On, Canada. In 1993, he was a visiting researcher at Sony headquarters in Tokyo, Japan. He joined the Microelectronics Division of IBM, Toronto, Canada in 1994, where he was involved in the development of infrared wireless networking products.In 2000, he joined the University of Toronto where he is currently an Assistant Professor in the Edward S. Rogers Senior Department of Electrical and Computer Engineering. His research interests include analog integrated circuits, optical communication systems, and integrated circuits for biomedical applications.     

A Novel Nonlinear Precoding Algorithm for the Downlink of Multiple Antenna Multi-User Systems

By pre-equalizing inter-stream interference at the transmitter, Tomlinson–Harashima precoding (THP) algorithm provides a solution for the downlink of multiple antenna multi-user systems, in which the decentralized structure of the receivers makes the receiver-processing impossible. However, for the zero-forcing (ZF) THP algorithm available in the literature there are significant performance differences between specific mobile stations. In this paper, a novel version of the THP algorithm is proposed. It greatly improves the worst mobile's performance and ensures balanced performance of all the mobiles. For the new THP algorithm, better performance can be obtained by suitably ordering the rows of the channel matrix. We show that the “best-first” ordering method achieves optimal order for BER performance in systems with two mobile stations and achieves near optimal order in systems with more than two mobile stations. Simulation is used to show the advantages of the new THP algorithm and the “best-first” ordering method. Jia Liu received the B.E. and M.Sc. degrees in electrical engineering from Beijing University of Posts and Telecommunications, Beijing, China, in 1998 and 2001, respectively. Between 2001 and 2002, she worked as a system engineer in Siemens Ltd. (China), ICM N R&D, TD-SCDMA. She is currently pursuing a Ph.D. degree at the Department of Electrical and Computer Engineering, University of Alberta, and at TRLabs in Edmonton, Alberta, Canada. Her current research interests include broadband wireless communications, multiple input multiple output (MIMO) antenna systems, precoding for multi-user MIMO, signal detection, and multi-user interference cancellation. Witold A. Krzymień received his M.Sc. (Eng.) and Ph.D. degrees (both in Electrical Engineering) in 1970 and 1978, respectively, from the Poznań University of Technology in Poznań, Poland. He received a Polish national award of excellence for his PhD thesis. Since April 1986 he has been with the Department of Electrical & Computer Engineering at the University of Alberta, Edmonton, Alberta, Canada, where he currently holds the endowed Rohit Sharma Professorship in Communications & Signal Processing. In 1986, he was one of the key research program architects of the newly launched TRLabs, Canada's largest industry-university-government pre-competitive research consortium in the Information & Communication Technology area, headquartered in Edmonton. His research activity has been closely tied to the consortium ever since. Over the years Dr. Krzymień has also done collaborative research work with Nortel Networks, Ericsson Wireless Communications, German Aerospace Centre (DLR -Oberpfaffenhofen), Telus Mobility and the University of Padova (Italy). He has held visiting research appointments at Twente University of Technology (Enschede, The Netherlands; 1980-1982), Bell-Northern Research (Montréal, Canada; 1993-1994), Ericsson Wireless Communications (San Diego, USA; 2000), Nortel Networks Harlow Laboratories (Harlow, UK; 2001), and the Department of Information Engineering at the University of Padova (2005). His research is currently focused on broadband high throughput packet data access for mobile and nomadic users, employing multi-carrier signalling, multiple antenna techniques and link adaptation, as well as on the related MAC and network layer issues of hybrid ARQ, packet scheduling and relaying. Dr. Krzymień is a Fellow of the Engineering Institute of Canada, and a licensed Professional Engineer in the Provinces of Alberta and Ontario, Canada. From 1999 to 2005 he was the Chairman of Commission C (Radio Communication Systems and Signal Processing) of the Canadian National Committee of URSI (Union Radio Scientifique Internationale). He received the 1991/1992 A.H. Reeves Premium Award from the Institution of Electrical Engineers (U.K.) for a paper published in the IEE Proceedings, Part I.     

Dynamically anchored conferencing handoff for dual-mode cellular/WLAN handsets

In this paper we consider vertical handoff for enterprise-based dual-mode (DM) cellular/WLAN handsets. When the handset roams out of WLAN coverage, the DM's cellular interface is used to maintain the call by anchoring it through an enterprise PSTN gateway/PBX. Soft handoff can be achieved in this case if the gateway supports basic conference bridging, since a new leg of the call can be established to the conference bridge while the existing media stream path is active. Unfortunately this requires that all intra-enterprise calls be routed through the gateway when the call is established. In this paper we consider a SIP based architecture to perform conferenced dual-mode handoff and propose a much more scalable mechanism for short-delay environments, whereby active calls are handed off into the conference bridge prior to the initiation of the vertical handoff. Results are presented which are taken from a dual-mode handset testbed, from analytic models, and from simulations which characterize the scalability of the proposed mechanism. Mohammed Smadi received the B.Eng and Mgmt and M.A.Sc degrees in Computer Engineering from McMaster University in Hamilton, Ontario, Canada. Mohammed received an NSERC doctoral award in 2005 and is currently a Ph.D. student at the Wireless Networking Group at McMaster University. Terence D. Todd received the B.A.Sc, M.A.Sc and Ph.D. degrees in Electrical Engineering from the University of Waterloo, Waterloo, Ontario, Canada. While at Waterloo he spent 3 years as a Research Associate with the Computer Communications Networks Group (CCNG). He is currently a Professor of Electrical and Computer Engineering at McMaster University in Hamilton, Ontario, Canada. Professor Todd spent 1991 on research leave in the Distributed Systems Research Department at AT&T Bell Laboratories in Murray Hill, NJ. He also spent 1998 on research leave at The Olivetti and Oracle Research Laboratory in Cambridge, England. While at ORL he worked on the piconet project which was an early embedded wireless network testbed. Dr. Todd’s research interests include metropolitan/local area networks, wireless communications and the performance analysis of computer communication networks and systems. He is a past Editor of the IEEE/ACM Transactions on Networking and currently holds the NSERC/RIM/CITO Chair on Pico-Cellular Wireless Internet Access Networks. Dr. Todd is a Professional Engineer in the province of Ontario and a member of the IEEE. Vytas Kezys was born in Hamilton, Canada in 1957. He received the B.Eng. degree in Electrical Engineering from McMaster University, Canada, in 1979. From 1979 to 1998, Mr. Kezys was involved in radar and communications research as Principal Research Engineer at the Communications Research Laboratory, McMaster University. While at McMaster, his research activities included array signal processing for low-angle tracking radar, radar signal processing, and smart antennas for wireless communications. Mr. Kezys was founder and President of TalariCom Inc., a start-up company that developed cost effective smart antenna technologies for broadband wireless access applications. Currently, Mr. Kezys is Director of Advanced Products at Research in Motion in Waterloo, Canada. Vahid S. Azhari received his B.S. and M.S. from the Department of Electrical and Computer Engineering, IUST and University of Tehran, Iran, in 2000 and 2003 respectively. His M.S. research focused on designing scheduling algorithms for switch fabrics. He also worked for two years for the Iranian Telecommunication Research Centre on developing software for SDH switches. He is currently pursuing his Ph.D. degree at the Wireless Networking Laboratory, McMaster University, Canada. His main area of research includes handoff management in integrated wireless networks, WLAN deployment techniques, and wireless mesh networks. Dongmei Zhao received the Ph.D. degree in Electrical and Computer Engineering from the University of Waterloo, Waterloo, Ontario, Canada in June 2002. Since July 2002 she has been with the Department of Electrical and Computer Engineering, McMaster University, Hamilton, Ontario, Canada where she is an assistant professor. Dr. Zhao’s research interests include modeling and performance analysis, quality-of-service provisioning, access control and admission control in wireless cellular networks and integrated cellular and ad hoc networks. Dr. Zhao is a member of the IEEE.     

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.     

Analysis of Sub-Carrier Multiplexed Radio Over Fiber Link for the Simultaneous Support of WLAN and WCDMA Systems

The present third generation (3G) wireless technology can provide data oriented applications. However, the bit rate is limited to around 2 Mbps with limited mobility. Today, more applications demand high data rate and reasonable mobility. Therefore, by integrating 3G cellular system and wireless local area network (WLAN), there is a potential to push the data rate higher. This integration means 3G cellular users can enjoy high data rate at a location that is within WLAN coverage area. Similarly, WLAN users also can have data services as long as they are under the coverage of the 3G cellular system. The 3G cellular system has a much larger coverage than the WLAN. In this paper, we present the first step toward an integration of the two systems. This paper presents a fiber-wireless architecture that simultaneously supports the wideband code division multiple access (WCDMA) system and the IEEE 802.11b WLAN. Our approach uses sub-carrier multiplexed (SCM) architecture to combine and transmit 2.4 GHz WLAN and 1.9 GHz WCDMA signals through an optical fiber from a central base station (CBS) to a radio access point (RAP, single antenna unit). After the fiber, the signals continue to propagate through the air interface to respective mobile stations. The WLAN access point is also located at the CBS. For the SCM architecture, we investigate three areas: i) the signal to noise ratio of the uplink and the downlink, ii) the cell coverage area for the WCDMA and WLAN systems, and iii) the throughput of the IEEE 802.11b WLAN. Our results show that with up to 2.5 km cell radius, better than 18 dB SNR is possible with 5 km fiber link for WLAN system. Simultaneously, the WCDMA system has at least 18 dB SNR for a cell coverage radius of 8 km. These numbers depend on the relative RF power of each system in the fiber.Roland M.C. Yuen received a Bachelor of Electrical Engineering degree in 2003 from Ryerson University, Toronto, Canada. He is pursuing a Master of Applied Science degree at Ryerson University. He has a conference paper. His research interests are in the area of optical and wireless communications.Currently, he works on unique fiber based architecture to extend the capability of cellular networks and support wireless LANs simultaneously.Xavier N. Fernando () obtained B.Sc. Eng. (First Class Honors) degree from Sri Lanka, where he was first out of 250 students. He got Master’s degree from the Asian Institute of Technology (Bangkok) Ph.D. from the University of Calgary, Canada in affiliation with TRLabs. He has worked for AT&T for three years as an R&D Engineer. Currently he is an Assistant Professor at Ryerson University, Toronto, Canada.Dr. Fernando one US patent and about 38 peer reviewed publications in journals and conference proceedings. His research focuses on signal processing for cost-effective broadband multimedia delivery via optical wireless networks. Dr. Fernando′s work won the best research paper award in the Canadian Conference of Electrical and Computer Engineering for the year 2001. His student projects won both the first and second prize at Opto Canada – the SPIE regional conference in Ottawa in 2002. He is a senior member of IEEE, member of SPIE, Chair of the IEEE Communications Society Toronto Chapter and licensed Professional Engineer in Ontario, Canada. He has many research grants including Canadian Foundation of Innovations (CFI), Ontario Innovations Trust (OIT) and Natural Sciences and Engineering Research Council (NSERC) of Canada.     

Performance of multiuser network-aware prefetching in heterogeneous wireless systems

We study the performance of multiuser document prefetching in a two-tier heterogeneous wireless system. Mobility-aware prefetching was previously introduced to enhance the experience of a mobile user roaming between heterogeneous wireless access networks. However, an undesirable effect of multiple prefetching users is the potential for system instability due to the racing behavior between the document access delay and the user prefetching quantity. This phenomenon is particularly acute in the heterogeneous environment. We investigate into alleviating the system traffic load through prefetch thresholding, accounting for server queuing prioritization. We propose a novel analysis framework to evaluate the performance of the thresholding approach. Numerical and simulation results show that the proposed analysis is accurate for a wide variety of access, service, and mobility patterns. We further demonstrate that stability can be maintained even under heavy usage, providing both the same scalability as a non-prefetching system and the performance gain associated with prefetching. A preliminary version of this article was presented in the International Conference on Quality of Service in Heterogeneous Wired/Wireless Networks (QShine) 2006. This work was supported in part by the Natural Sciences and Engineering Research Council of Canada and Bell Canada through its Bell University Laboratories R&D program. Ben Liang received honors simultaneous B.Sc. (valedictorian) and M.Sc. degrees in electrical engineering from Polytechnic University in Brooklyn, New York, in 1997 and the Ph.D. degree in electrical engineering with computer science minor from Cornell University in Ithaca, New York, in 2001. In the 2001–2002 academic year, he was a visiting lecturer and post-doctoral research associate at Cornell University. He joined the Department of Electrical and Computer Engineering at the University of Toronto as an Assistant Professor in 2002. His current research interests are in mobile networking and multimedia systems. He received an Intel Foundation Graduate Fellowship in 2000 toward the completion of his Ph.D. dissertation, the Best Paper Award at the IFIP Networking conference in 2005, and the Runner-up Best Paper Award at the International Conference on Quality of Service in Heterogeneous Wired/Wireless Networks in 2006. He is a senior member of IEEE and a member of ACM and Tau Beta Pi. He serves on the organizational and technical committees of a number of major conferences each year. Stephen Drew received his B.A.Sc with honours in Computer Engineering from the University of Waterloo in 2003, and his M.A.Sc in Electrical Engineering at the University of Toronto in 2005 under the supervision of Ben Liang of the Communications group. He is currently employed by General Dynamics Canada, in the engineering research and development team. Da Wang is a third year Electrical Engineering student at the University of Toronto. He has been a recipient of the Adel S. Sedra Outstanding Student Award, the IEEE Canada-Toronto Section Scholarship and the Nortel Institute Undergraduate Scholarship. He held an NSERC award for the summer of 2005.     

An Efficient Architecture for a Lifted 2D Biorthogonal DWT

This paper presents a new algorithm for a 2D non-separable lifted bi-orthogonal wavelet transform. The algorithm is derived by factoring complementary pairs of wavelet transform 2D filters. The results are efficient architectures for real time signal processing, which do not require transpose memory for the 2D processing of data. The proposed architecture exploits in place implementation, inherit from the algorithm, and can take advantage of both vertical and horizontal parallelism in the direct implementation. The processing in our architecture is scheduled by carefully pipelining the lifted steps, which allows for up to four times faster processing than the direct implementation. The proposed architecture operates at high speed, consumes low power and has reduced computational complexity as compared to previously published filter and lifted based bi-orthogonal wavelet architectures.M. Alam (Student) is currently M.Sc. student in the Department of Electrical and Computer Engineering at University of Calgary. His research interest includes VLSI signal processing. He is recipient of iCORE International Graduate Scholarship.Wael Badawy (Ph.D. 00, M.Sc 98, 97; B.Sc. 94) is an associate professor in the Department of Electrical and Computer Engineering. He holds an adjunct professor in the Department of Mechanical Engineering, University of Alberta.Dr. Badawys research interests are in the areas of: Microelectronics, VLSI architectures for video applications with low-bit rate applications, digital video processing, low power design methodologies, and VLSI prototyping. His research involves designing new models, techniques, algorithms, architectures and low power prototype for novel system and consumer products. Dr. Badawy authored and co-authored more than 100 peer reviewed Journal and Conference papers and about 30 technical reports. He is the Guest Editor for the special issue on System on Chip for Real-Time Applications in the Canadian Journal on Electrical and Computer Engineering, the Technical Chair for the 2002 International Workshop on SoC for real-time applications, and a technical reviewer in several IEEE journals and conferences. He is currently a member of the IEEE-CAS Technical Committee on Communication. Dr. Badawy was honored with the 2002 Petro Canada Young Innovator Award, 2001 Micralyne Microsystems Design Award and the 1998 Upsilon Pi Epsilon Honor Society and IEEE Computer Society Award for Academic Excellence in Computer Disciplines. He is currently the Chairman of the Canadian Advisor Committee (CAC) and Head of the Canadian Delegation on ISO/IEC/JTC1/SC6 Telecommunications and Information Exchange Between Systems. Member, The Canadian Advisory Committee for the Standards Council of Canada-Subcommittee 29: Coding of Audio, Picture Multimedia and Hypermedia Information, and Canadian Delegate, The ISO/IEC MPEG standard committee. He is a voting Member on the VSI Alliance. He is also the Chair of the IEEE-Southern Alberta Society-Computer Chapter.Vassil S. Dimitrov was born in Plovdiv, Bulgaria, in 1964. He received his Ph.D. degree in mathematics in 1995 from the Mathematical Institute of the Bulgarian Academy of Sciences. Since then, he has spent two years as a postdocral fellow at the VLSI Research Group, University of Windsor, Canada, one year as a research scientist at the Reliable Software Technology Corporation, Virginia, USA, one year as a chief research scientist at the Signal Processing and Computer Technology Laboratory, Helsinki University of Technology, Finland, and one year as an Associate Professor at the University of Windsor, Canada. Since July 2001 he has held the position of Associate Professor at the Department of Electrical and Computer Engineering, University of Calgary, Canada. His main interests are in the area of number theoretic algorithms, computational complexity, cryptography, optimization theory, fast algorithms for digital signal processing and related topics. Dr. Dimitrov is a member of the New York Academy of Sciences.Graham Jullien (Fellow IEEE) was educated in the United Kingdom, receiving degrees, in Electrical Engineering, from the Universities of Loughborough, Birmingham and Aston (Ph.D., 1969). He was a student engineer and data processing engineer at English Electric Computers, UK, from 1961 to 1966, and a visiting senior research engineer at the Central Research Laboratories of EMI Ltd., UK, from 1975 to 1976. From 1969 until 2000 he was with the Department of Electrical and Computer Engineering at the University of Windsor, Ontario, Canada, where he held the rank of University Professor and was the Director of the VLSI Research Group. Since January 2001, he has been with the Department of Electrical and Computer Engineering at the University of Calgary, where he holds the iCORE Research Chair in Advanced Technology Information Processing Systems. He is a member of the Board of Directors of the Canadian Microelectronics Corporation (CMC) and is a member of the Steering Committee and Board of Directors of the Micronet Network of Centres of Excellence. He has published widely in the fields of Digital Signal Processing, Computer Arithmetic, Neural Networks and VLSI Systems, and teaches courses in related areas. He has served on the technical committees of many international conferences; he currently serves on the Editorial Board of the Journal of VLSI Signal Processing; and is a past Associate Editor of the IEEE Transactions on Computers. He hosted and was program co-chair of the 11th IEEE Symposium on Computer Arithmetic, was program chair for the 8th Great Lakes Symposium on VLSI, and was the technical program chair for the 1999 Asilomar Conference on Signals, Systems and Computers. He is general chair for the 2003 Asilomar Conference and general co-chair of the International Workshop on System-on-Chip for Real-Time Systems, Calgary, Alberta 2003.     

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.     

8 GHz 1V, CMOS quadrature downconverter for wireless applications

The design and implementation of an 8 GHz CMOS quadrature downconverter, achieving simultaneously low voltage supply operation and good linearity is presented in this paper. This is achieved by relaxing the inherent tradeoff between power conversion gain and linearity governing all active mixers and implementing a mixer using a new version of the bias-offset technique. The quadrature generator uses active inductors embodied in the LO buffer, and provides easy tuning by relaxing the coupling between amplitude and phase tuning of the outputs. It also provides reduced power consumption by eliminating the buffers located between the quadrature generator and the mixers. A prototype implemented in a 0.18 μm CMOS technology occupies an area of 0.44 × 0.3 mm², operates from a 1V power supply and features an IIP3 of +3.5 dBm, an IIP2 of better than +48 dBm, an input compression point of −5.5 dBm, a power conversion gain of +6.5 dB for the mixers and a quadrature phase and amplitude matching of better than 1.5° and 1 dB respectively over a bandwidth of 100 MHz after tuning. The overall power consumption of the quadrature downconverter is 25.8 mW. Farsheed Mahmoudi was born in Tehran, Iran. He received his B.Sc. and M.Sc. degrees in Electronics from the University of Tehran, Tehran, Iran in 1997 and 2000 respectively. He is currently working toward the Ph.D. degree at the University of Toronto, Toronto, Canada. His research interests include the design and analysis of RF circuits and systems for wireless applications. C. Andre T. Salama received the B.A.Sc. (Hons.) M.A.Sc. and Ph. D. degrees, all in Electrical Engineering, from the University of British Columbia in 1961, 1962 and 1966 respectively. From 1962 to 1963 he served as a Research Assistant at the University of California, Berkeley. From 1966 to 1967 he was employed at Bell Northern Research, Ottawa, as a Member of Scientific Staff working in the area of integrated circuit design. Since 1967 he has been on the staff of the Department of Electrical and Computer Engineering, University of Toronto where he held the J.M. Ham Chair in Microelectronics from 1987 to 1997. In 1992, he was appointed to his present position of University Professor for scholarly achievements and preeminence in the field of microelectronics. In 1989–90, he was awarded the ITAC/NSERC Research Fellowship in information technology. In 1994, he was awarded the Canada Council I.W. Killam Memorial Prize in Engineering for outstanding career contributions to the field of microelectronics. In 2000, he received the IEEE Millenium Medal. In 2003, he received the Outstanding Lifetime Achievement Award from the Canadian Semiconductor Technology Conference for seminal and outstanding contributions to semiconductor device research and promotion of Canadian University research in microelectronics. In 2004, he received the NSERC Lifetime Achievement Award of Research Excellence for outstanding and sustained contributions to the field of microelectronics and the Networks of Centres of Excellence (NCE) Recognition Award for research excellence and outstanding leadership. He was associate editor of the IEEE Transactions on Circuits and Systems in 1986–88 and a member of the International Electron Devices Meeting (IEDM) Technical Program Committee in 1980–82, 1987–89 and 1996–98. He was the chair of the Solid State Devices Subcommittee for IEDM in 1998 and was a member of the editorial board of Solid State Electronics from 1984 to 2002. He is presently a member of the editorial board of the Analog IC and Signal Processing Journal and the Technical Program Committee of the International Symposium on Power Semiconductor Devices and ICs (ISPSD) and the Technical Program Committee of the International Symposium on Low Power Electronics and Design (ISLPED). He chaired the technical program committee of ISPSD in 1996 and was the general chair for the conference in 1999. Dr. Salama is the Scientific Director of Micronet, a network of centres of excellence focussing on microelectronics research and funded by the Canadian Government and Industry. He has published extensively in technical journals, is the holder of eleven patents and has served as a consultant to the semiconductor industry in Canada and the U.S. His research interests include the design and fabrication of semiconductor devices and integrated circuits with emphasis on deep submicron devices as well as circuits and systems for high speed, low power signal processing applications. Dr. Salama is a Fellow of the Institute of Electrical and Electronics Engineers, a Fellow of the Royal Society of Canada, a Fellow of the Canadian Academy of Engineering, a member of the Association of Professional Engineers of Ontario, the Electrochemical Society and the Innovation Management Association of Canada.     

Wide dynamic range parallel feedback transimpedance amplifier for 10 Gb/s optical links

This paper presents the design and implementation of a new wide dynamic range parallel feedback (PF) transimpedance amplifier (TIA) for 10 Gb/s optical links. The wide dynamic range is attributed to the novel TIA architecture employing both shunt-shunt and shunt-series feedback networks. The outstanding features of the TIA are wide dynamic range, high gain, low power consumption and design simplicity. A prototype implemented in a 0.5 μm SiGe BiCMOS technology and operating at −3.3 V power supply features an 18.4 dBm dynamic range with a BER less than 10⁻¹², an optical sensitivity of −16 dBm, optical overload of +2.4 dBm, a bandwidth of 8.27 GHz, a gain of 950 Ω and a power consumption of 189 mW. The new parallel feedback architecture offers improved overload and noise performance when compared to previously reported, state of the art, single feedback TIA designs and meets all the 10 Gigabit Ethernet and short-reach OC-192 SONET specifications. Ricardo Andres Aroca received the B.S. (Hons) degree in electrical engineering from the University of Windsor, Canada, and the M.S. degree from the University of Toronto, Canada, in 2001 and 2004, respectively. In 2000 he spent two 4 month internships with Nortel Networks in the Microelectronics Department. Mr. Aroca received the Natural Sciences and Engineering Research Counsel of Canada (NSERC) Postgraduate Scholarship award in 2002. He is currently working toward the Ph.D. degree at the University of Toronto where his research interests lie in the area of high-frequency integrated circuits for wireless and wireline communication systems. C. Andre T. Salama received the B.A.Sc. (Hons.) M.A.Sc. and Ph. D. degrees, all in Electrical Engineering, from the University of British Columbia in 1961, 1962 and 1966 respectively. From 1962 to 1963 he served as a Research Assistant at the University of California, Berkeley. From 1966 to 1967 he was employed at Bell Northern Research, Ottawa, as a Member of Scientific Staff working in the area of integrated circuit design. Since 1967 he has been on the staff of the Department of Electrical and Computer Engineering, University of Toronto where he held the J.M. Ham Chair in Microelectronics from 1987 to 1997. In 1992, he was appointed to his present position of University Professor for scholarly achievements and preeminence in the field of microelectronics. In 1989-90, he was awarded the ITAC/NSERC Research Fellowship in information technology. In 1994, he was awarded the Canada Council I.W. Killam Memorial Prize in Engineering for outstanding career contributions to the field of microelectronics. In 2000, he received the IEEE Millenium Medal. In 2003, he received the Outstanding Lifetime Achievement Award from the Canadian Semiconductor Technology Conference for seminal and outstanding contributions to semiconductor device research and promotion of Canadian University research in microelectronics. In 2004, he received the NSERC Lifetime Achievement Award of Research Excellence for outstanding and sustained contributions to the field of microelectronics and the Networks of Centres of Excellence (NCE) Recognition Award for research excellence and outstanding leadership.He was associate editor of the IEEE Transactions on Circuits and Systems in 1986–88 and a member of the International Electron Devices Meeting (IEDM) Technical Program Committeein 1980–82, 1987–89 and 1996–98. He was the chair of the Solid State Devices Subcommittee for IEDM in 1998 and was a member of the editorial board of Solid State Electronics from 1984 to 2002. He is presently a member of the editorial board of the Analog IC and Signal Processing Journal and the Technical Program Committee of the International Symposium on Power Semiconductor Devices and ICs (ISPSD) and the Technical ProgramCommittee of the International Symposium on Low Power Electronics and Design (ISLPED). He chaired the technical program committee of ISPSD in 1996 and was the general chair for the conference in 1999.Dr. Salama is the Scientific Director of Micronet, a network of centres of excellence focussing on microelectronics research and funded by the Canadian Government and Industry. He has published extensively in technical journals, is the holder of eleven patents and has served as a consultant to the semiconductor industry in Canada and the U.S. His research interests include the design and fabrication of semiconductor devices and integrated circuits with emphasis on deep submicron devices as well as circuits and systems for high speed, low power signal processing applications. Dr. Salama is a Fellow of the Institute of Electrical and Electronics Engineers, a Fellow of the Royal Society of Canada, a Fellow of the Canadian Academy of Engineering, a member of the Association of Professional Engineers of Ontario, the Electrochemical Society and the Innovation Management Association of Canada.