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International Conference on Acoustics, Speech, and signal processing (ICASSP)

作者： T. Adali S.H. Ardalan Dept. of Electr. & Comput. Eng. North Carolina State Univ. Raleigh NC USA Center of Communications and Signal Processing Department of Electrical and Computer Engineering North Carolina State University Raleigh NC USA

The authors derive the steady-state mean square prediction error expression for the fixed-point RLS (recursive least squares) algorithm for the case of time-varying channel estimation, which is modeled as a first-order Markov tapped delay line. It is shown that the random variable driving the time-varying system taps affects the prediction error in the same way as does the roundoff error term due to weight update. It causes the error to grow linearly with time when the forgetting factor, lambda , is chosen as 1. For lambda <1, the excess error tends to increase when the data are correlated. However, this effect is not direct as in the cases of the additive noise and the roundoff error due to the desired signal estimate.< >

关键词： Roundoff errors Error analysis Algorithm design and analysis Resonance light scattering Steady-state Least squares approximation Time-varying channels Delay estimation Recursive estimation Predictive models

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The stabilization of two‐dimensional non‐symmetric half‐plane recursive filters via the discrete Hilbert transformations

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International Journal of Circuit Theory and Applications 1991年第1期19卷 1-8页

作者： Reddy, C.R. Sathyanarayana, P. Swamy, M.N.S. Centre for Signal Processing and Communications Department of Electrical and Computer Engineering Concordia University Montreal H3G IM8 1455 de Maisonneuve Blvd. West Canada

The discrete Hilbert transform (DHT) relations for 2D semicausal signals have been introduced. an alternative algorithm to stabilize non‐symmetric half‐plane (NSHP) recursive filters by applying the DHT directly in the nonsymmetric half‐plane is presented. the results of the direct DHT (DDHT) stabilization procedure are compared with the method of quarter‐plane DHT (QDHT) stabilization after transforming the NSHP polynomial into the quarter‐plane by application of an appropriate transformation. It is observed that the proposed scheme produces the same stable NSHP filter as that obtained through the QDHT method. Copyright © 1991 John Wiley & Sons, Ltd.

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FULL-WAVE SOLUTION OF DIELECTRIC LOADED WAVE-GUIDES AND SHIELDED MICROSTRIPS UTILIZING FINITE-DIFFERENCE AND THE CONJUGATE-GRADIENT METHOD

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INTERNATIONAL JOURNAL OF MICROWAVE AND MILLIMETER-WAVE computer-AIDED engineering 1991年第4期1卷 346-357页

作者： NARAYANAN, V MANELA, M LADE, RK SARKAR, TK Department of Electrical and Computer Engineering Syracuse University Syracuse New York 13244-1240 Viswanathan Narayanan was born in Bangalore India on December 14 1965. He received the BE degree in Electronics and Communications from B.M.S. College of Engineering Bangalore in 1988. He joined the Department of Electrical Engineering at Syracuse University for his graduate studies in 1989 where he is currently a research assistant. His research interests are in microwave measurements numerical electromagnetics and signal processing. Biographies and photos are not available for M. Manela and R. K. Lade. Tapan K. Sarkar (Sf69-M'76-SM'X1) was born in Calcutta. India on August 2 1948. He received the BTech degree from the Indian Institute of Technology Kharagpur India in 1969 the MScE degree from the University of New Brunswick Fredericton Canada in 1971. and the MS and PhD degrees from Syracuse University. Syracuse NY in 1975. From 1975-1976 he was with the TACO Division of the General Instruments Corporation. He was with the Rochester Institute of Technology (Rochester NY) from 1976-1985. He was a Research Fellow at the Gordon Mckay Laboratory Harvard University Cambridge MA from 1977 to 1978. He is now a Professor in the Department of Electrical and Computer Engineering Syracuse University. His current research interests deal with numerical solutions of operator equations arising in electromagnetics and signal processing with application to system design. He obtained one of the “ best solution” awards in May 1977 at the Rome Air Development Center (RADC) Spectral Estimation Workshop. He has authored or coauthored more than 154 journal articles and conference papers and has written chapters in eight books. Dr. Sarkar is a registered professional engineer in the state of New York. He received the Best Paper Award of the IEEE Transactions on Electromagnetic Compatibility in 1979. He was an Associate Editor for feature articles of the lEEE Antennas arid Propagation Sociefy Newsletter and was

Dynamic analysis of waveguide structures containing dielectric and metal strips is presented. The analysis utilizes a finite difference frequency domain procedure to reduce the problem to a symmetric matrix eigenvalue problem. Since the matrix is also sparse, the eigenvalue problem can be solved quickly and efficiently using the conjugate gradient method resulting in considerable savings in computer storage and time. Comparison is made with the analytical solution for the loaded dielectric waveguide case. For the microstrip case, we get both waveguide modes and quasi-TEM modes. The quasi-TEM modes in the limit of zero frequency are checked with the static analysis which also uses finite difference. Some of the quasi-TEM modes are spurious. This article describes their origin and discusses how to eliminate them. Numerical results are presented to illustrate the principles.

关键词： Waveguides

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OPTIMIZATION OF TRANSMITTER AND RECEIVER FILTERS FOR DIGITAL-COMMUNICATION SYSTEMS USING MEAN FIELD ANNEALING

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IEEE JOURNAL ON SELECTED AREAS IN communications 1990年第8期8卷 1472-1480页

作者： NOBAKHT, RA VANDENBOUT, DE TOWNSEND, JK ARDALAN, SH Center of Communications and Signal Processing Department of Electrical and Computer Engineering North Carolina State University Raleigh NC USA

A technique for finding transmitter and receiver filters for a wide class of digital communication systems which minimize the bit-error rate (BER) is presented. The technique uses Monte Carlo simulation to estimate the BER and mean field annealing (MFA) to optimize the pulse shapes. Modeling of the link can be as complex as simulation will allow, while MFA is resistant to the statistical variation in the BER estimate from the simulation. Initially, the MFA technique was applied to a binary symmetric channel in a nonsimulation environment, and an approximate analysis of the behavior of MFA for this problem was performed. In a more complex example, MFA was coupled with Monte Carlo simulation techniques to find near-optimal transmit and receive filters for a satellite communications link, taking 6 CPU hours on a DECstation 3100. The BER of the link was found to be as much as three orders of magnitude lower when using the MFA-constructed optimal filters than when using filters from other comparison results. For this example, the pulse shapes obtained using MFA exhibit a low BER even as the parameter controlling the nonlinearity of the satellite-link model is varied over a wide range, thus showing the solution is robust.< >

关键词： Transmitters Digital filters Bit error rate Pulse shaping methods Shape control Digital communication Simulated annealing Performance analysis Satellite communication Robust control

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THE COMPLEX CEPSTRUM AND BICEPSTRUM - ANALYTIC PERFORMANCE EVALUATION IN THE PRESENCE OF GAUSSIAN-NOISE

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IEEE TRANSACTIONS ON ACOUSTICS SPEECH AND signal processing 1990年第7期38卷 1246-1256页

作者： PETROPULU, AP NIKIAS, CL Communication and Digital Signal Processing Center for Research and Graduate Studies Department of Electrical and Computer Engineering Northeastern University Boston MA USA

An analytic performance evaluation of the complex cepstrum, power cepstrum, bicepstrum, and power bicepstrum is presented by providing approximate expressions of the bias and variance of the cepstrum parameters due to the presence of Gaussian noise. The approximations are based on the asymptotic properties of bispectrum estimates, and they are valid for moderate signal-to-noise ratios (SNRs). The assumed model consists of a deterministic signal (e.g. multiple echoes) in additive white Gaussian noise and finite length data. The validity of the analytic expressions is verified with Monte Carlo simulations. Performance comparisons between bicepstrum and cepstrum methods suggest that the improved performance of the bicepstrum is a function of SNR, A( omega ), M, and N.< >

关键词： Cepstrum Cepstral analysis Performance analysis Gaussian noise signal to noise ratio signal analysis Additive noise Delay effects Noise measurement Spectral analysis

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DISCRETE TIME-VARYING FILTER AND PLL FOR SYNCHRONOUS ESTIMATION OF PARAMETERS OF A SINE signal CORRUPTED BY A CLOSELY SPACED FM INTERFERENCE

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signal processing 1990年第2期21卷 183-194页

作者： WULICH, D PLOTKIN, EI SWAMY, MNS Centre for Signal Processing and Communications Department of Electrical and Computer Engineering Concordia University 1455 De Maisonneuve Blvd. Montreal Quebec H3G 1M8 Canada

The concept of time-varying filters as applied to the problem of rejection of a sine signal with fast variations of frequency is explored. Using such filters, a method for synchronous (i.e., when frequency is known) estimation of phase and amplitude of a sine wave corrupted by closely spaced sinusoidal interference with fast frequency variations is proposed. It is shown that the coefficients of the time-varying filter can be effectively determined using a Phase Locked Loop. It is proved that the performance of the proposed estimator depends neither on the interference level nor on the speed of frequency variations. Comparison with an adaptive estimator based on a linear time invariant filter shows the superiority of the proposed one where the interference frequency changes rapidly over time. Das Konzept der Anwendung zeitvarianter Filter zur Unterdrückung eines Sinnusignals schnell veränderlicher Frequenz wird erforscht. Auf der Grundlage solcher Filter wird ein Verfahren vorgeschlagen, mit der die Phase und die Amplitude eines Sinussignals synchron (d.h., bei bekannter Frequenz) geschätzt werden können, das durch dicht benachbarte Sinuskomponenten schnell variierender Frequenzen gestört ist. Es wird gezeigt, daß die Koeffizienten des zeitveränderlichen Filters mit Hilfe einer Phase-Locked-Loop effizient bestimmt werden können. Es wird nachgewiesen, daß die Leistungsfähigkeit des vorgeschlagenen Schätzers weder vom Störpegel noch von der Geschwindigkeit der Frequenzänderungen abhängt. Der Vergeich mit einem adaptiven Schätzer auf der Basis eines linearen zeitinvarianten Filters zeigt, daß der neue Vorschlag im Falle schneller Frequenzänderungen des Störsignals überlegen ist. Le concept de filters variant dans le temps, comme dans le problème de rejection d'un signal sinusoïdal de fréquence à variation rapide, est exploré. En utilisant de tels filters, une méthode est proposée pour l'estimation synchrone (c'est-à-dire, quand la fréquence est connue) de la phase et de

关键词： Time-varying filters estimation PLL

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Subband coding of video with adaptive vector quantization

Subband coding of video with adaptive vector quantization

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International Conference on Acoustics, Speech, and signal processing (ICASSP)

作者： A.N. Akansu M.S. Kadur Electrical and Computer Engineering Department Center for Communications and Signal Processing Research Newark NJ USA

A low bit rate adaptive video coding technique is proposed. The redundancy within adjacent video frames is exploited by motion-compensated interframe prediction, and the motion-compensated frame difference (MCFD) signal is decomposed by using a quadrature mirror filter (QMF) structure. The subband signals are vector quantized adaptively. The MCFD signals are low correlated, hence transform coding techniques are not very suitable for this kind of signal source. At 0.25-0.3 bits/pixel range, 38-40-dB peak-to-peak signal-to-noise ratio is achieved with the proposed scheme for four monochrome test sequences used: cindy, mono, duo, and quartet. The visual quality of the encoded test sequences is good, almost indistinguishable from the originals. The proposed technique outperforms the adaptive transform coding and adaptive vector quantization techniques for the tested sequences.< >

关键词： Vector quantization Testing Transform coding Bit rate Video coding Mirrors Filters signal to noise ratio MONOS devices

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Pose determination using tree annealing

Pose determination using tree annealing

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IEEE International Conference on Robotics and Automation (ICRA)

作者： Y.-S. Han W.E. Snyder G.L. Bilbro Center for Communications and Signal Processing Department of Electrical and Computer Engineering North Carolina State University USA

The problem of pose determination of a surface in a range image is described as a six-degree-of-freedom optimization problem, where the surface is expressed by a quadratic equation. The tree annealing algorithm, a general-purpose technique for finding minima of functions of continuously valued variables, is presented. The technique is applied to the pose determination of analytic surfaces and is shown to be quite effective even in the presence of considerable amounts of noise in the images.< >

关键词： Equations Simulated annealing signal processing algorithms Surface fitting Minimization methods Image sensors Transforms Visualization

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Point pattern matching by a genetic algorithm

Point pattern matching by a genetic algorithm

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Annual Conference of Industrial Electronics Society

作者： N. Ansari M.-H. Chen E.S.H. Hou Center for Communications and Signal Processing Department of Electrical and Computer Engineering New Jersey Institute of Technology Newark NJ USA

The problem of finding a subset of points in a pattern that best match to a subset of points in another pattern through a transformation in an optimal sense is considered. An exhaustive search to find the best assignment mapping one set of points to another set is, if the number of points that are to be matched is large, computationally expensive. A genetic algorithm that searches for the best ('almost the best') assignment efficiently is described. To map the point pattern matching into the framework of a genetic algorithm, a fitness function that is inversely proportional to the match error and a scheme for encoding an assignment between two sets of points into a string are used, along with a genetic operator known as the mixed-type partial matching crossover. Experimental results have demonstrated the robustness and the fast convergence of the algorithm. The algorithm can be applied to n-dimensional point patterns and any transformation. Results are presented for two-dimensional point patterns and a similarity transformation.< >

关键词： Pattern matching Genetic algorithms signal processing algorithms Shape Robustness Convergence computer vision Pattern recognition Motion estimation Stochastic processes

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A useful and general technique for improving the efficiency of Monte Carlo simulation of digital communication systems

A useful and general technique for improving the efficiency ...

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[Proceedings] GLOBECOM '90: IEEE Global Telecommunications Conference and Exhibition

作者： M. Devetsikiotis J.K. Townsend Center for Communications and Signal Processing Department of Electrical & Computer Engineering North Carolina State University Raleigh NC USA

Importance sampling is a potentially powerful method for reducing simulation runtimes when estimating the bit error rate (BER) of communications systems using Monte Carlo simulation. Analytically minimizing the variance of the importance sampling estimator with respect to the biasing parameters has only yielded solutions for systems for which the bit error rate (BER) could be found analytically (i.e., a linear system with additive Gaussian noise). A technique for finding a near-optional set of biasing parameters for the translation biasing scheme is presented. A key feature of this technique is that repetitive, very short simulation runs are used to determine near-optimal translation values. The method is also shown to exploit a theoretically justifiable relationship, for small sample sizes, between the BER estimate and the amount of translation. Only mild assumptions about the noise distribution and system are required. Experimentally, improvement factors ranging from three to eight orders of magnitude are obtained for different avalanche photodiode noise distributions.< >

关键词： Bit error rate Monte Carlo methods Analysis of variance Runtime Communication systems Yield estimation Linear systems Additive noise Gaussian noise Avalanche photodiodes

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