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MILCOM, Military Communications Conference

作者： R.E. Kamel Y. Bar-Ness Center for Communications and Signal Processing Department of Electrical and Computer Engineering New Jersey Institute of Technology Newark NJ USA Telecommunications & Traffic-Control Systems Group Delft University of Technnology Delft Netherlands

The decision feedback equalizer has the advantage of compensating for channel amplitude distortion without enhancing noise. Conventional decision feedback equalizers require a training sequence to help them adapt to unknown channel characteristics. Training sequences are not always appropriate. In such situations blind equalizers are more suitable. The blind decision feedback equalizer inherits from the conventional the advantage of not enhancing noise, while compensating for severe ISI. It is thus superior over the blind linear equalizer. On the other hand the blind decision feedback equalizer also suffers from error propagation. In this paper we study the transient behavior of the blind DFE. This is done by deriving an upper bound on the probability of error due to residual ISI and show that it vanishes for the noiseless case. We also determine lower and upper bounds on the probability of error for the additive white Gaussian noise case. The upper bound obtained is the same as that of Duttweiler, et al. (1974). Using a different approach from that of Duttweiler, et al., we derive a lower bound. This bound is tighter than tile "no ISI" lower bound.< >

关键词： Decision feedback equalizers Decorrelation Upper bound Blind equalizers Intersymbol interference Additive white noise Steady-state Convergence Gaussian noise AWGN

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PERFORMANCE OF A PRIORITIZED ON-BOARD BASEBAND SWITCH FOR A MULTISERVICE MULTIBEAM SATELLITE

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INTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS 1994年第3期12卷 283-297页

作者： BOHM, S ELHAKEEM, AK HACHICHA, M Department of Electrical and Computer Engineering Concordia University 1455 De Maisonneuve Blvd. West Montreal H3A 1M8 Canada Was born in Montreal Canada on 14 September 1966. He received the B. Eng. degree in electrical engineering from Concordia University Montreal Canada in 1989. He is at present completing the M.A.Sc. degree in electrical engineering at Concordia University. (S'75–S'79–M'79–SM'86) received the Ph.D. degree from Southern Methodist University Dallas TX in 1979. He spent the next two years working as a Visiting Professor in Egypt after which he moved to Ottawa Canada in 1982. He assumed teaching and research positions in Carleton and Manitoba Univerities and later moved to Concordia University Montreal Canada in 1983 where he is now a Professor in the Electrical and Computer Engineering Department. He has published numerous papers in IEEE and international journals in the areas of spread spectrum and networking. He is a well-known expert in these areas and serves as a consultant to many companies. His current research interests include wide-band metropolitan networks switching architectures and performance of on-board multibeam satellites acquisitionless CDMA networks code distribution and orthogonalization of CDMA signals responsive congestion control for ATM-based networks ARQ techniques and investigation of the novel SUGAR CDMA systems in fading channels. Dr. Elhakeem is a Senior Member of the Canadian Electrical Engineering Society and Armed Forces Association. He has chaired numerous technical sessions in IEEE Conferences was the Technical Program Chairman for IEEE Montech 1986 Montreal Canada. Dr. Elhakeem is the key guest editor of theIEEE Journal of Selected Areas in Communicationsfor the May June issues 1993 covering CDMA networks. Advanced Technology & Networks VISTAR Telecommunications Inc. Ottawa Ontario K1G 3J4 Canada An Associate Director of Advanced Technology & Networks Group VISTAR Telecommunications Inc. Ottawa Canada. He is also an Adjunct Pr

In this paper, we study the performance of a prioritized on-board baseband switch in conjunction with a multibeam satellite handling integrated services. The services considered for the analysis include voice, video, file transfer and interactive data. The prioritized switch uses both input and output buffering, switch speed-up as well as a two-phase head-of-line resolution algorithm, in order to reduce the buffer loss while maintaining acceptable user delays. The minimum required buffer capacity and switch speed-up for each service in a prioritized environment are found under uniform traffic conditions. It is shown that under uniform traffic conditions, only minimal buffering and switch speed-up are needed even for the lowest priority users. The performance dependence on the switch size is also substantially reduced with head of line resolution and buffering even in a prioritized environment.

关键词： SWITCH ON-BOARD BASEBAND MULTIBEAM PRIORITIZED HEAD-OF-LINE UNIFORM LOAD SPEED-UP

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ANALYSIS OF A MOVABLE BOUNDARY ACCESS TECHNIQUE FOR A MULTISERVICE MULTIBEAM SATELLITE SYSTEM

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INTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS 1994年第3期12卷 299-312页

作者： BOHM, S ELHAKEEM, AK MURTHY, KMS HACHICHA, M KADOCH, M Department of Electrical and Computer Engineering Concordia University 1455 De Maisonneuve Blvd. West Montreal H3A 1M8 Canada Was born in Montreal Canada on 14 September 1966. He received the B. Eng. degree in electrical engineering from Concordia University Montreal Canada in 1989. He is at present completing the M.A.Sc. degree in electrical engineering at Concordia University. (S'75–S'79–M'79–SM'86) received the Ph.D. degree from Southern Methodist University Dallas TX in 1979. He spent the next two years working as a Visiting Professor in Egypt after which he moved to Ottawa Canada in 1982. He assumed teaching and research positions in Carleton and Manitoba Univerities and later moved to Concordia University Montreal Canada in 1983 where he is now a Professor in the Electrical and Computer Engineering Department. He has published numerous papers in IEEE and international journals in the areas of spread spectrum and networking. He is a well-known expert in these areas and serves as a consultant to many companies. His current research interests include wide-band metropolitan networks switching architectures and performance of on-board multibeam satellites acquisitionless CDMA networks code distribution and orthogonalization of CDMA signals responsive congestion control for ATM-based networks ARQ techniques and investigation of the novel SUGAR CDMA systems in fading channels. Dr. Elhakeem is a Senior Member of the Canadian Electrical Engineering Society and Armed Forces Association. He has chaired numerous technical sessions in IEEE Conferences was the Technical Program Chairman for IEEE Montech 1986 Montreal Canada. Dr. Elhakeem is the key guest editor of theIEEE Journal of Selected Areas in Communicationsfor the May June issues 1993 covering CDMA networks. Advanced Technology & Networks VISTAR Telecommunications Inc. Ottawa Ontario K1G 3J4 Canada . He is ITU's Specialist Consultant and Chief Advisor for a number of ITU/UNDP projects including VSATs Rural Networks Digital Broadc

In this paper, the performance of a new movable boundary accessing (MBA) technique for future integrated services multibeam satellite systems is studied. The multiservice environment considered includes both asynchronous and isochronous traffic consisting of video, voice, file transfer and interactive data. The movable boundary access technique proposed here will maximize the utilization of the up-link frame capacity. It is shown that the potential user population is substantially increased with the use of a moving boundary policy with minimal overhead.

关键词： MOVABLE BOUNDARY ACCESS TECHNIQUE MF-TDMA DAMA MULTIBEAM SATELLITE

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A method for recognizing character strings from maps using linguistic knowledge

A method for recognizing character strings from maps using l...

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International Conference on Document Analysis and Recognition

作者： A. Nakamura O. Shiku M. Anegawa C. Nakamura H. Kuroda Department of Electrical Engineering and Computer Science Faculty of Engineering Nagasaki University Nagasaki Japan Department of Control Engineering Sasebo National College of Technology Nagasaki Japan

It is difficult to recognize character strings from maps, which involve various figures. The authors describe a method for recognizing character strings from these topographical maps. The method consists of a bottom-up process and a top-down process. First, in the bottom-up process, character candidates are extracted from a map. Second, in the top-down process, these character candidates are grouped into strings using linguistic knowledge of strings. Through the top-down process, character strings are recognized correctly and efficiently from low precise character candidates extracted through the bottom-up process. The method was applied to 13 maps (512/spl times/512 pixels) involving 98 strings. As a result, 95% of 98 strings were extracted correctly.< >

关键词： Character recognition Roads Carbon capture and storage control engineering Knowledge engineering Data mining Buildings Educational institutions Image recognition Dictionaries

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Tracking controller for Systems Containing a Stiff Nonlinearity

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IFAC Proceedings Volumes 1993年第2期26卷 179-182页

作者： Dong H. Chyung Dong-Jin Lim Sang-Chul Won University of Iowa Department of Electrical and Computer Engineering Iowa City Iowa 52242 USA Hanyang University Department of Instrumentation and Control Ansan Kyung Ki Korea Pohang Institute of Technology Department of Electronic Engineering Pohang KyungBuk Korea

In this paper, we present a method for designing a robust tracking controller for systems containing a nondifferentiable nonlinearitiy. It is also assumed that state variables are only partially observable for feedback and so the controller must be based on the observable vector only. The system response must follow a given reference input with zero steady state error and satisfy certain transient requirements such as the settling time, rise time, smoothness and overshoot. It should also cancel the effects of external disturbances and must be robust with respect to parameter variations. The proposed controller is based on augmenting the given system with additional integrators and implementing time delayed feedback controllers. If the system contains a limit cycle, then the describing function method for delay systems is used to eliminate the limit cycle.

关键词： Non-differentiable nonlinearities Nonlinear control systems Tracking systems Partial state feedback Delays

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A Frequency-domain Robust Instability Criterion for Time-varying and Non-linear Systems

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IFAC Proceedings Volumes 1993年第2期26卷 59-64页

作者： Y.Z. Tsypkin D.J. Hill A.J. Isaksson Control Sciences Institute Russian Academy of Sciences Moscow Russia Department of Electrical and Computer Engineering The University of Newcastle NSW 2308 Australia Department of Signals Sensors and Systems Royal Institute of Technology S-100 44 Stockholm Sweden

This paper presents an instability version of an earlier result by Tsypkin and Polyak (1991) on robust stability analysis using a modified Nyquist plot. The result is shown to be useful for presenting robust stability... 详细信息

关键词： Robust instability time-varying systems nonlinear systems circle criteria Nyquist criterion

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Robust Pole Placement Using Two-Pole Dominant Models

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IFAC Proceedings Volumes 1993年第2期26卷 9-13页

作者： P. Padmanabhan C.V. Hollot W. Siegl Department of Electrical and Computer Engineering University of Massachusetts Amherst MA 01003 USA Automatic Control Laboratory Swiss Federal Institute of Technology ETH-Zürich CH-8092 Zürich Switzerland

In this paper, we consider the problem of robust pole placement using fixed-order compensation. It is assumed that the coefficients of the numerator and denominator polynomials of the uncertain plant depend muitilinearly on the "parameters" and that the design specifications are given in the form of a two-pole dominant model. We present a design methodology for choosing a fixed-order compensator which ensures that all the roots of the closed loop polynomial lie in the regions prescribed by the two-pole dominant model.

关键词： Uncertain Plant Robust Pole Placement Two-Pole Dominant Model

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Worst Case Identification of Continuous time Systems via Interpolation

Worst Case Identification of Continuous time Systems via Int...

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American control Conference (ACC)

作者： Jie Chen Guoxiang Gu Carl N. Nett Schools of AeroSpace and Electrical Engineering Georgia Institute of Technology Atlanta GA USA Department of Electrical and Computer Engineering Louisiana State University Baton Rouge LA USA Laboratory for Identification and Control of Complex Highly Uncertain Systems(LIC-CHUS) School of Aerosapce Engineering Georgia Institute of Technology Atlanta GA USA

We consider a worse case control oriented identification problem recently studied by several authors. This problem is one of the H∞ identification in the continuous time setting. We give a less conservative formulation of this problem. The available apriori information consists of a lower bound on the relative stability of the plant, a frequency dependent upper bound on a certain gain associated with the plant, and an upper bound on the noise level. The available experimental information consists of a finite number of noisy plant point frequency response samples. The objective is to identify from the given apriori and experimental information an uncertain model that includes a stable nominal plant model and a bound on the modeling error measured in H∞ norm. Our main contributions include both a new identification algorithm and several new explicit lower and upper bounds on the identification error. The algorithm proposed belongs to the class of interpolatory algorithms which are known to possess a desirable optimality property under a certain criterion. The error bounds presented improve upon the previously available ones in both the aspects of providing a more accurate estimate of the identification error as well as establishing a faster convergence rate for the proposed algorithm.

关键词： Continuous time systems Interpolation Upper bound control systems Frequency Convergence Sampling methods Stability Noise level System identification

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New Vertex Results in Establishing the Strictly Positive Realness of Weighted Interval Systems

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IFAC Proceedings Volumes 1993年第2期26卷 329-334页

作者： C.V. Hollot L. Guzzella R. Tempo F. Kraus M. Mansour Department of Electrical and Computer Engineering University of Massachusetts Amherst MA 01003 USA Automatic Control Laboratory Swiss Federal Institute of Technology ETH-Zürich CH-8092 Zürich Switzerland CENS-CNR Politecnico di Torino Corso Duca degli Abruzzi 24 10129 Torino Italy

For a given plant transfer function P ( s ) and cone size k, solutions to versions of the absolute stability problem boil down to finding a SPR multiplier Z ( s ) such that [ k ¯ - 1 + P ( s ) ] Z ( s ) is SPR. In this paper, we consider an interval plant P ( s , q , r ) and prove that first order multiplierslead to vertex results when establishing the positive realnells of [ k ¯ - 1 + P ( s , q , r ) ] Z ( s ) . Additionally, we give an example of a second order multiplier and interval plant which fails to have this vertex property. These new results are then applied to the problem of robust stability of time-varying interval systems.

关键词： Vertex Results Strictly Positive Realness Weighted Interval Systems

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Steady‐state modelling of a uniform pulse‐width modulated single‐phase AC‐to‐DC converter‐fed DC motor drive

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European Transactions on electrical Power 1993年第5期3卷 379-386页

作者： Hamed, S.A. Dr. Sadeq A. Hamed (1957) received his B.Sc. degree in Electrical Power Engineering from Damascus University Syria in 1980. From 1980 to 1982 he has been with the Department of Electrical Engineering at the University of Jordan Ammad/Jordan. He obtained the M.Sc. degree in Power Electronics and Systems and the PhD degree in Power Electronics from the University of Manchester Institute of Science and Technology (UMIST) Manchester/GB in 1983 and 1986 respectively. In 1986 he joined the Department of Electrical Engineering. Jordan University as an Assistant Professor. In 1991 became an Associate Professor at the same department. His research activities include modelling and simulation of AC/DC drive systems pulse-width modulation control of motor implementation of computer-controlled drive systems energy saving in the electrical drive industry. (Jordan University Department of Electrical Engineering Amman/Jordan T + 96 26/843555 - 28 13 Fax + 9626/8485 58)

With the increasing availability of power transistor switches, PWM controlled rectifiers can efficiently and economically be employed in low and medium power applications of DC drive systems. In this paper, steady‐state modelling and solution of a uniform pulse‐width modulated single‐phase AC‐to‐DC converter‐fed DC motor drive is accomplished. The developed model is presented in a generalized form that is applicable irrespective of the number of pulses per supply half‐cycle. Measured and predicted parameters are shown to be very close and the model is proved to be efficient and accurate. Both continuous and discontinuous modes of operation are covered, and critical operating conditions at which the system moves from one mode to the other are thoroughly investigated. The effects of the armature inductance‐to‐resistance ratio and the chopping frequency on these critical conditions, load and line harmonics, and on the ripple contents of the armature current are also thoroughly investigated. Copyright © 1993 John Wiley & Sons, Ltd.

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