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IEEE Symposium on Advances in Digital Filtering and signal processing

作者： Wei-Ping Zhu M. Omair Ahmad M.N.S. Szamy Center for Signal Processing and Communications Department of Electrical and Computer Engineering Concordia University Montreal QUE Canada Concordia University Montreal QC CA

It has been shown by some researchers that in a problem of weighted least-square (WLS) design of an FIR filter, most of the design computation pertains to the evaluation of the inverse of a matrix in order to solve a system of equations. A new iterative procedure is developed for the inversion of the matrices involved in the design. By expanding the inverse of a matrix as a convergent series, an updating formula for evaluating the inverse for each iteration is obtained, so that the proposed algorithm requires an inverse for only a few initial iterations but does not need any numerical operations for matrix inversion in succeeding iterations. It is also shown that the proposed iterative procedure is applicable for a wide range of weighting functions used for least-square designs.

关键词： Finite impulse response filter signal design Equations Iterative algorithms Design methodology Frequency response signal processing signal processing algorithms Design optimization Costs

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Parameter-free structural modeling: a contribution to the solution of the separation of highly correlated AR-signals

Parameter-free structural modeling: a contribution to the so...

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IEEE International Symposium on Circuits and Systems (ISCAS)

作者： E.I. Plotkin M.N.S. Swamu Center for Signal Processing and Communications Department of Electrical and Computer Engineering Concordia University Montreal QUE Canada Concordia University Montreal QC CA

This paper develops the concepts and properties of composite parameter structural (CPS) modeling, and shows how such properties can be exploited for the separation of very highly correlated autoregressive signals. A CPS model recently developed and used to represent a signal of a given structure (given order of an AR model) but of unknown, or partially unknown, parameters, is investigated. The main feature of the described CPS model is the utilization in its design of almost ideal null filters, resulting in low noise sensitivity. The performance of the proposed algorithms is analyzed using computer simulations.

关键词： Finite impulse response filter Convergence Steady-state

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Adaptive heterodyne filters (AHF) for detection and attenuation of narrow band signals

Adaptive heterodyne filters (AHF) for detection and attenuat...

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

作者： K.E. Nelson M.A. Soderstrand Electrical and Computer Engineering Department Digital Signal Processing and Communications Laboratory USA University of California Davis CA USA

A fixed filter may be converted into an adaptive filter with a single adaptation parameter through the use of a new adaptive heterodyne filter (AHF) concept in which the frequency of the heterodyne signal is adjusted thereby translating the entire filter transfer function in frequency. If the fixed filter is selected to be a very narrow-band band-pass filter, the new AHF concept can be used very effectively in the elimination of narrow band interference in wide-band communications or control systems. A specific example of the removal of a slow-moving time-varying mechanical resonance from the control signal for a flight control system demonstrates the power of the new AHF concept.

关键词： Adaptive filters Attenuation Band pass filters Frequency conversion Narrowband Communication system control Control systems Transfer functions Interference elimination Wideband

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Sonar resolution-based environment mapping 15

Sonar resolution-based environment mapping

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15th IEEE International Conference on Robotics and Automation, ICRA 1998

作者： Cahut, Leyla Vlavanis, Kimon P. Delic, Hakan Robotics and Automation Laboratory Center for and Advanced Computer Studies University of Southwestern Louisiana LafayetteLA70504 United States Signal and Image Processing Laboratory Department of Electrical Engineering BogaziCi University Bebek 80815 Istanbul Turkey

ISBN: (纸本)078034300X

Ultrasonic range sensors are used to obtain the information required for collision-free navigation of a mobile robot in a semi-structured or unstructured environment. A set of range readings from a ring of sonars are correlated to acquire a 2D map of the robot's environment. The map is continuously enhanced via novel matching and update algorithms as new data are collected while the robot is in motion. The algorithm utilizes confidence measures that are directly obtained from the sonar's resolution or accuracy. There are no additional modeling assumptions and the approach is robust. The algorithms are experimentally tested on the Nomad 200 mobile robot and Nomad's Cognos Software Development Package. © 1998 IEEE.

关键词： Software testing

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Multistage detector for adaptive separation of QAM-modulated multiuser CDMA signals

Multistage detector for adaptive separation of QAM-modulated...

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IEEE International Symposium on Spread Spectrum Techniques and Applications

作者： Y. Bar-Ness N.J.M. van Waes Center for Communications and Signal Processing Research Department of Electrical Engineering New Jersey Institute of Technology Newark NJ USA

Code division multiple access (CDMA) proves to be an attractive method for multiuser communication due to its potential capacity increase and anti-multipath fading capability. However, its performance is limited by the existence of multiple access interference energy (MAI), which results in the so called near-far problem. To reduce the MAI effect, different structures for multiuser separators have been proposed. Among these are different decorrelating detectors, adaptive and non-adaptive. One of these adaptive decorrelators is the so called "bootstrap" decorrelator. To further improve performance, multi-stage receivers has also been proposed using as a second stage a fixed canceler that depends on knowing the signals amplitude or an adaptive canceler that needs no such knowledge. All these different detection methods assumed BPSK modulation. For high bit/cycle modulation such as QAM, one can extend the BPSK based detectors by modifying them to PAM and handle the I and Q rails separately. However, considering the QAM as complex modulation signals, we propose in this paper the generalized complex bootstrap, and implement it in a multi-stage receiver, which can handle multiuser M-QAM data. Simulation results showed the adequacy of the scheme in improving the performance of the detection by reducing the MAI.

关键词： Adaptive signal detection Detectors Multiaccess communication Multiple access interference Decorrelation Fading Binary phase shift keying Quadrature amplitude modulation Time division multiple access Power control

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Implementing the bootstrap algorithm to multi-shot matched filtering, multiuser detection

Implementing the bootstrap algorithm to multi-shot matched f...

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Mediterranean Electrotechnical Conference (MELECON)

作者： Y. Bar-Ness N.J.M. Van Waes Center for Communications and Signal Processing Research Department of Electrical Engineering New Jersey Institute of Technology Newark NJ USA

CDMA proves to be an attractive method for multiuser communication due to its potential capacity increase and anti-multipath fading capability. However, its performance is limited by the existence of multiuser interference energy (MI), which results in the so called near-far problem. To reduce the MI effect, different decorrelating structures for multiuser detection have been proposed. For the asynchronous case, the "one-shot decorrelator" was proposed, based on inversion of the partial correlation matrix, which may however be singular. As an alternative, the so-called "multi-shot decorrelator", which does not suffer from the aforementioned singularities, was also suggested. However, both detectors, based on inversion of some matrix, are not robust to errors in the users' relative delays. The application of the adaptive "bootstrap algorithm" with the one-shot structure proved to easily handle variation in delay estimates and outperform the decorrelating detector. We propose and compare a bootstrap algorithm suitable for the multi-shot matched filtering, multiuser detector in a multipath environment, examine its performance, and compare it to that of other detectors.

关键词： Decorrelation Detectors Delay estimation Multiaccess communication Fading Interference Multiuser detection Robustness Filtering algorithms Matched filters

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Recovering depth from stereo using ART neural networks

Recovering depth from stereo using ART neural networks

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

作者： S. Markogiannakis E.S. Manolakos Communications and Digital Signal Processing CDSP Center Electrical and Computer Engineering Department Northeastern University Boston MA USA Northeastern University Boston MA US

One of the long standing problems in passive stereo vision is that of constructing a range map using only two images providing two views of the same 3-D world scene. It amounts to identifying pairs of corresponding pixels, one pixel in each image, that are associated with the same point on the 3-D world. We are introducing ART-1 neural networks as a primitive capable of addressing the stereo correspondence problem. Using a multi-pass approach it is possible to increase gradually the density of matched points, while at the same time false matches are filtered by requiring close agreement between disparity estimates in a neighborhood. At the end, a reasonably dense disparity map is obtained, to the extent that it allows the reconstruction of the scene using interpolation methods. Our scheme has been tested on stereograms, virtual world scenes generated by computer programs (where the "ground truth" is known) as well as real-world scenes. In all cases the scene reconstructions are shown to be quite realistic.

关键词： Subspace constraints Neural networks Layout Neurons Tiles Strips Pixel Image reconstruction Pattern matching Interpolation

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Edge preserving image restoration using convex optimization

Edge preserving image restoration using convex optimization

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IEEE International Conference on Image processing

作者： K.G. Srinidhi D.H. Brooks Communication and Digital Signal Processing Center Department of Electrical and Computer Engineering Northeastern University Boston MA USA

Restoring an original image from its blurred and noisy version is usually ill-posed. l/sub 2/ norm based regularized inverse solutions lead to restored images with the edges blurred. Some work has focused on using the l/sub 1/ norm of the gradient as a regularizer. Alternatively convex optimization approaches have been used to provide flexibility to impose multiple constraints on the solution. In this paper, we combine these methods using a convex optimization approach based on the ellipsoid algorithm to impose, among other constraints, an l/sub 1/ norm of the gradient constraint. This results in a restored image with good edge preservation capabilities.

关键词： Image restoration Ellipsoids signal processing algorithms Constraint optimization Image reconstruction Iterative algorithms signal restoration Digital signal processing Smoothing methods Optimization methods

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A comparison of GSM receivers for fading multipath channels with adjacent and co-channel interference

A comparison of GSM receivers for fading multipath channels ...

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IEEE International Symposium on Personal, Indoor and Mobile Radio communications (PIMRC)

作者： B.A. Bjerke J.G. Proakis M.K. Lees Z. Zvonar Communications and Digital Signal Processing CDSP Center Department of Electrical and Computer Engineering Northeastern University Boston MA USA Communications Division Analog Devices Inc.orporated Wilmington MA USA

In this paper, we evaluate low complexity detectors for use in the GSM system. In particular, we compare the performance of decision feedback equalization (DFE) and nonlinear data directed estimation (NDDE) to that of the optimal maximum likelihood sequence estimation (MLSE). Establishing the performance of the basic NDDE detector is a first step in investigating the applicability of block transmission techniques to the GSM system. Simulation results, obtained both for fading multipath channels and adjacent- and co-channel interference scenarios, show that the NDDE performs just as well as the DFE, and the performance of both low complexity detectors is comparable to that of the MLSE for the SNR region of interest in practical systems.

关键词： GSM Fading Multipath channels Maximum likelihood estimation Decision feedback equalizers Detectors Interchannel interference Time division multiple access Intersymbol interference Maximum likelihood detection

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A Region-Based Representation of Images in MARS

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Journal of VLSI signal processing Systems for signal, Image, and Video Technology 1998年第1-2期20卷 137-150页

作者： Servetto, Sergio D. Rui, Yong Ramchandran, Kannan Huang, Thomas S. Beckman Inst. Adv. Sci. and Technol. Univ. Illinois at Urbana-Champaign Urbana IL 61801 United States Universidad Nacional de La Plata Argentina Univ. Illinois at Urbana-Champaign United States Comp. Res. Adv. Applications Group IBM Argentina Argentina Image Formation and Processing Group Beckman Institute UIUC United States Department of Computer Science UNLP Argentina Dept. of Elec. and Comp. Engineering UIUC United States Multimedia Commun. Res. Department Bell Laboratories Murray Hill NJ United States Info. Sciences Research Department AT and T Labs. Florham Park NJ United States Department of Computer Science UIUC United States Southeast University China Tsinghua University China University of Illinois Urbana-Champaign IL United States Image Formation and Processing Group Beckman Inst. Advance Sci. Technol. UIUC United States Vis. Technol. Grp. of Microsoft Res. Redmond WA United States City College of New York United States Columbia University United States AT and T Bell Labs. United States Ctr. for Telecommunications Research Columbia University United States Elec. and Comp. Eng. Department United States Beckman Institute Coordinated Science Laboratory IL United States IEEE Signal Processing Society United States IEEE IMDSP Technical Committee United States IEEE Transactions on Image Proc. United States National Taiwan University Taipei Taiwan Massachusetts Inst. of Technology Cambridge MA United States Department of Electrical Engineering MIT United States School of Electrical Engineering United States Lab. for Info. and Signal Processing Purdue University United States Dept. of Elec. and Comp. Engineering United States Coordinated Science Laboratory United States Image Formation and Processing Group Beckman Inst. Adv. Sci. and Technol. United States MIT Lincoln Laboratory IBM Thomas J. Watson Research Center Rheinishes Landes Museum Bonn Germany Swiss Institutes of Technology Zurich Switzerland Swiss Institutes of Technology Lausanne S

We study the problem of representing images within a multimedia Database Management System (DBMS), in order to support fast retrieval operations without compromising storage efficiency. To achieve this goal, we propose new image coding techniques which combine a wavelet representation, embedded coding of the wavelet coefficients, and segmentation of image-domain regions in the wavelet domain. A bitstream is generated in which each image region is encoded independently of other regions, without having to explicitly store information describing the regions. Simulation results show that our proposed algorithms achieve coding performance which compares favorably, both perceptually and objectively, to that achieved using state-of-the-art image/video coding techniques while additionally providing region-based support.

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