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International Symposium on signals, Circuits and Systems (ISSCS)

作者： I. Cleju P. Franti Xiaolin Wu Multimedia Signal Processing Group Department of Computer and Information Science University of Karlsruhe Konstanz Germany Speech and Image Processing Research Group Department of Computer Science University of Joensuu Joensuu Finland Multimedia Computing and Comucations Laboratory Department of Etectrical and Computer Engineering McMaster University Hamilton ONT Canada

Data clustering is intensively used in signal processing in tasks such as multimedia compression, segmentation and pattern matching. In this work we extend the use of principal curves in clustering to complex multidimensional datasets. The use of principal curve in clustering is limited for high complexity data. Automatic parameterization of the principal curve to assure good results for different datasets is a difficult task. We propose to use the tree structure to capture the general settlement of the data. Using this topology, regions of the dataset can be extracted, individually clustered using the principal curve and then optimally recombined. The experiments show the improvement of the new method over the principal curve based clustering and the good performance compared to other clustering methods.

关键词： Tree data structures Clustering algorithms Partitioning algorithms multimedia computing Quantization computer science Pattern matching Data mining Application software Information science

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A Subspace-based Blind Channel Estimation For Zero-padded MC-CDMA

A Subspace-based Blind Channel Estimation For Zero-padded MC...

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Asia-Pacific Conference on Communications

作者： M. Wahab A.M. Zoubir Department of Electrical and Computer Engineering Curtin University of Technology Perth Australia Signal Processing Group Technische Universitat Darmstadt Darmstadt Germany

A subspace-based blind channel estimation for multicarrier CDMA system employing zero-padding (ZP) technique is proposed in this paper. This ZP technique is mainly used for mitigating the effect of channel zeros on the performance of the MC-CDMA in the wireless channels. An adaptive algorithm for this channel estimation is also proposed in order to reduce the computational complexity. Performance evaluation is presented for downlink and uplink transmission in the presence of channel zeros. Simulation results show that the channel estimator and the MC-CDMA system perform well in the presence of channel zeros

关键词： Blind equalizers Multicarrier code division multiple access Channel estimation OFDM Fading Multiple access interference Downlink Virtual colonoscopy Multiaccess communication Bit error rate

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On The Selection of Significant Multipath Components For Parsimonious DS-CDMA RAKE Receivers: A Covariance Bootstrap Based Approach

On The Selection of Significant Multipath Components For Par...

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Asia-Pacific Conference on Communications

作者： A.A. Abd El-Sallam Yee Hong Leung A.M. Zoubir Department of Electrical and Computer Engineering Curtin University of Technology Perth WA Australia Signal Processing Group Technische Universitat Darmstadt Darmstadt Germany

We consider a bootstrap based approach to identify the significant multipath parameters of a frequency selective slowly fading channel. The channel response is modelled as an FIR filter with length proportional to the channel delay-spread. We estimate the model parameters the time domain using the auto and cross-correlation functions. Based on the estimates, bootstrap based multiple hypothesis tests are then applied to identify the significant coefficients of the FIR filter. Simulation results demonstrate the power of this technique to design high performance and low complexity RAKE receivers

关键词： Multiaccess communication Fading Multipath channels Frequency Finite impulse response filter Delay Parameter estimation Testing Wideband Maximum likelihood estimation

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A frequency domain sphericity test based approach for parsimonious rake receivers in CDMA systems

A frequency domain sphericity test based approach for parsim...

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International Symposium on signal processing and Its Applications (ISSPA)

作者： A.A. El-sallam Y.H. Leung A.M. Zoubir Communications & Signal Processing Group Department of Electrical & Computer Engineering Curtin University of Technology Perth WA Australia Signal Theory Group Institute for Communication Technology Darmstadt University of Technology Merckstrasse Germany

A frequency domain approach is presented for parsimonious channel estimation which can result in the implementation of a low complexity DS-CDMA RAKE receiver. We consider frequency selective slowly fading channels. A new approach is proposed to identify and estiamte only significant channel parameters. The approach uses the sphericity test and delay estimation methods based on averaged periodogram techniques. Simulations show that, with short training sequences and low signal to noise ratio, the proposed technique can correctly identify the significant channel parameters. Also the parsimonious RAKE receiver based on these estimates gives improved statistical as well as computational performance over classical methods.

关键词： Frequency domain analysis System testing Fading Multipath channels Multiaccess communication Baseband signal processing Correlators Fingers Delay

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Cost-effective video filtering solution for real-time vision systems

Cost-effective video filtering solution for real-time vision...

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作者： Fischer, Viktor Lukac, Rastislav Martin, Karl Laboratoire Traitement du Signal et Instrumentation Unité Mixte de Recherche CNRS 5516 Université Jean Monnet 10 rue Barrouin 42000 Saint-Etienne France Multimedia Laboratory Edward S. Rogers Sr. Department of Electrical and Computer Engineering University of Toronto 10 King's College Road Toronto Ont. M5S 3G4 Canada Jean Monnet University of Saint-Etienne France Department of Electronics and Computer Science Micronic Košice Slovakia Edward S. Rogers Sr. Department of Electrical and Computer Engineering University of Toronto Toronto Canada IEEE Circuits and Systems IEEE Consumer Electronics IEEE Signal Processing Societies IEEE Signal Processing Society Communications Society

This paper presents an efficient video filtering scheme and its implementation in a field-programmable logic device (FPLD). Since the proposed nonlinear, spatiotemporal filtering scheme is based on order statistics, its efficient implementation benefits from a bit-serial realization. The utilization of both the spatial and temporal correlation characteristics of the processed video significantly increases the computational demands on this solution, and thus, implementation becomes a significant challenge. Simulation studies reported in this paper indicate that the proposed pipelined bit-serial FPLD filtering solution can achieve speeds of up to 97.6 Mpixels/s and consumes 1700 to 2700 logic cells for the speed-optimized and area-optimized versions, respectively. Thus, the filter area represents only 6.6 to 10.5% of the Altera STRATIX EP1S25 device available on the Altera Stratix DSP evaluation board, which has been used to implement a prototype of the entire real-time vision system. As such, the proposed adaptive video filtering scheme is both practical and attractive for real-time machine vision and surveillance systems as well as conventional video and multimedia applications.

关键词： computer vision

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Design of frequency-invariant beamformers employing multi-dimensional Fourier transforms

Design of frequency-invariant beamformers employing multi-di...

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International Workshop on Multidimensional (nD) Systems

作者： Wei Liu S. Weiss Communications & Signal Processing Group Department of Electrical & Electronic Engineering Imperial College London London UK Communications Research Group School of Electronics & Computer Science University of Southampton UK

The design of a class of broadband arrays with frequency invariant beam patterns is studied and a simplified version of the design method employing multi-dimensional Fourier transforms is proposed with detailed account of each step. In the design examples, we give a mathematical explanation for the failure of this method in the lower frequencies. For a design with main beam pointing to a direction other than the broadside, the frequency invariant property is not good and two solutions for this problem are provided.

关键词： Frequency Fourier transforms Sensor arrays Filters Array signal processing signal design Educational institutions computer science Design methodology Two dimensional displays

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Channel coding for power line communication based on oversampled filter banks

Channel coding for power line communication based on oversam...

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IEEE International Symposium on Power Line Communications and Its Applications (ISPLC)

作者： C. Liu S. Weiss S. Redif T. Cooper L. Lampe J.G. McWhirter School of Electronics & Computer Science University of Southampton UK Advanced Signal Processing Group QinetiQ Limited Malvern UK Department of Electrical and Computer Engineering University of British Columbia Canada

Oversampled filter banks (OSFB) can be applied as channel coding and have shown benefits in correlated and impulsive noise. Therefore, in this paper, we consider such channel coders for a power line communications scenario, where such conditions create a hostile channel environment. The proposed channel coder assumes the knowledge of the noise covariance matrix. The transmission is accomplished over the N weakest eigenmodes of the noise, which are identified by means of a broadband eigenvalue decomposition. We demonstrate by simulations that this approach can lead to an enhancement of the SNR in the receiver and to improved performance over standard channel coding approaches.

关键词： Channel coding Power line communications Channel bank filters Working environment noise Programmable control signal to noise ratio Power system modeling Gaussian noise Filter bank Noise level

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An optimized systolic array architecture for full search block matching algorithm and its implementation on FPGA chips

An optimized systolic array architecture for full search blo...

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Annual IEEE Northeast Workshop on Circuits and Systems (NEWCAS)

作者： M. Mohammadzadeh M. Eshghi M.M. Azadfar ECE Faculty Shahid Beheshti University Iran Iran Telecommunication Research Center Iran Electrical and Computer Engineering Faculty Shahid Beheshti University Iran Multimedia and Signal Processing Group Iran Telecommunication Research Center Iran

In this paper, an optimized systolic array architecture for FSBMA is presented. This array architecture is implemented by RTL-level VHDL. It is synthesized for two FPGA families, Xilinx Spartan II and Xilinx Virtex II and the results for area occupation and maximum operating frequency are presented. The results show this array architecture is suitable for real-time video encoding systems with minimum hardware utilization and high performance.

关键词： Systolic arrays Field programmable gate arrays Hardware Motion estimation computer architecture signal processing algorithms Real time systems Parallel processing Telecommunications Pipeline processing

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About room response equalization and dereverberation

About room response equalization and dereverberation

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IEEE Workshop on Applications of signal processing to Audio and Acoustics

作者： M. Karjalainen T. Paatero J.N. Mourjopoulos P.D. Hatziantoniou Laboratory of Acoustics and Audio Signal Processing Helsinki University of Technology Finland Audio Group Wire Communications Lab Electrical and Computer Engineering Department University of Patras Patras Greece

Improvement of sound reproduction in rooms by signal processing techniques has been studied seriously for more than twenty years. Such methods are called for example dereverberation, room (response) equalization, and room (response) correction. Understanding the limitations and quality criteria for such methods is gradually achieved through studies of this highly multidimensional problem. In the present paper we discuss the terminology and goals, compare some recent approaches of these techniques in practical cases, and finally point out future challenges

关键词： Acoustic signal processing Multidimensional signal processing Multidimensional systems Terminology

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A generalized algorithm for the generation of correlated Rayleigh fading envelopes in wireless channels

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Eurasip Journal on Wireless Communications and Networking 2005年第5期2005卷 801-815页

作者： Tran, Le Chung Wysocki, Tadeusz A. Mertins, Alfred Seberry, Jennifer School of Electrical Computer and Telecommunications Engineering University of Wollongong Wollongong NSW 2522 Australia School of Electrical Computer and Telecommunications Engineering Faculty of Informatics University of Wollongong Wollongong NSW 2522 Australia Signal Processing Group Department of Physics University of Oldenburg 26111 Oldenburg Germany School of Information Technology and Computer Science Faculty of Informatics University of Wollongong Wollongong NSW 2522 Australia

Although generation of correlated Rayleigh fading envelopes has been intensively considered in the literature, all conventional methods have their own shortcomings, which seriously impede their applicability. A very general, straightforward algorithm for the generation of an arbitrary number of Rayleigh envelopes with any desired, equal or unequal power, in wireless channels either with or without Doppler frequency shifts, is proposed. The proposed algorithm can be applied to the case of spatial correlation, such as with multiple antennas in multiple-input multiple-output (MIMO) systems, or spectral correlation between the random processes like in orthogonal frequency-division multiplexing (OFDM) systems. It can also be used for generating correlated Rayleigh fading envelopes in either discrete-time instants or a real-time scenario. Besides being more generalized, our proposed algorithm is more precise, while overcoming all shortcomings of the conventional methods.

关键词： Rayleigh fading

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