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OCEANS

作者： A. Abdi H. Guo Center for Wireless Communication and Signal Processing Research Department of Electrical and Computer Engineering New Jersey Institute of Technology Newark NJ USA

ISBN: (纸本)9781424426195

A vector sensor measures the scalar and vector components of the acoustic field. Depending on the angle of arrivals and other channel characteristics, different types of correlation appear in a vector sensor array. These correlations affect the performance of a vector sensor communication system. In this paper a new statistical-geometrical framework is developed that provides parametric correlation formulas. These signal correlation expressions are useful for the design and performance analysis of vector sensor communication systems and signal processing algorithms. They can also be useful for estimating some important parameters of the channel such as angle spreads and angle of arrivals. Comparison of the proposed correlation model with experimental data illustrates the usefulness of the model.

关键词： Sensor arrays Sensor systems Underwater communication Sensor phenomena and characterization Acoustic sensors Acoustic measurements Underwater acoustics signal processing signal design Algorithm design and analysis

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Optical disc detection in retinal images

Optical disc detection in retinal images

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International Conference on Optimization of electrical and Electronic Equipment, OPTIM

作者： M. Ivanovici V. Scurtu Computers and Electronics Department Faculty of Electrical Engineering and Science IEEE Signal Processing and Communications Societies Computer Transilvania University of Brasov Brasov Romania Computers and Electronics Department Faculty of Electrical Engineering and Computer Science Transilvania Transilvania University of Brasov Brasov Romania

Lasers are currently used for a wide spectrum of medical applications, including the treatment of eye disorders. When combined with digital image processing techniques, the issue of retinal image segmentation becomes of high importance. In this paper, our purpose is twofold: i) to identify and briefly present the existing approaches for the retinal image segmentation and ii) to test our hypothesis that the Viola-Jones algorithm-initially designed for face detection-can be suited as well for optical disc detection.

关键词： Optical imaging Biomedical optical imaging Adaptive optics Training Histograms Optical saturation Optical filters

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Expanding Window Fountain codes for scalable video multicast

Expanding Window Fountain codes for scalable video multicast

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IEEE International Conference on Multimedia and Expo (ICME)

作者： Dejan Vukobratovic Vladimir Stankovic Dino Sejdinovic Lina Stankovic Zixiang Xiong Department of Communications and Signal Processing University of Novi Sad Novi Sad Serbia Department of Electronic and Electrical Engineering University of Strathclyde Glasgow UK Department of Electrical and Electronic Engineering University of Bristol Bristol UK Department of Electrical and Computer Engineering Texas A and M University College Station TX USA

Digital Fountain (DF) codes have recently been suggested as an efficient forward error correction (FEC) solution for video multicast to heterogeneous receiver classes over lossy packet networks. However, to adapt DF codes to low-delay constraints and varying importance of scalable multimedia content, unequal error protection (UEP) DF schemes are needed. Thus, in this paper, Expanding Window Fountain (EWF) codes are proposed as a FEC solution for scalable video multicast. We demonstrate that the design flexibility and UEP performance make EWF codes ideally suited for this scenario, i.e., EWF codes offer a number of design parameters to be ldquotunedrdquo at the server side to meet the different reception conditions of heterogeneous receivers. Performance analysis of H.264 Scalable Video Coding (SVC) multicast to heterogeneous receiver classes confirms the flexibility and efficiency of the proposed EWF-based FEC solution.

关键词： Receivers Streaming media PSNR Servers Forward error correction Error correction codes Real time systems

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The extended invariance principle applied to joint time-delay, frequency, and DOA estimation

The extended invariance principle applied to joint time-dela...

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

作者： Felix Antreich Josef A. Nossek Gonzalo Seco A. Lee Swindlehurst Institute for Communications and Navigation German Aerospace Center Wessling Germany Institute for Circuit Theory & Signal Processing Munich University of Technology Germany Department of Telecommunications & Systems Engineering Universitat Autonoma de Barcelona Spain Department of Electrical Engineering & Computer Science University of California Irvine CA USA

This paper deals with the joint estimation of temporal (time- delay, Doppler frequency) and spatial (direction-of-arrival, DOA) parameters of several replicas of a known signal in an unknown spatially correlated field. Unstructured and structured models have been proposed in the literature. The former suffers from a severe performance degradation in some scenarios, whereas the latter involves huge complexity. It is shown how the extended invariance principle (EXIP) can be applied to obtain estimates with the quality of those of the structured model, but with the complexity of the unstructured one. We present a method to improve the quality of the time- delay and Doppler estimates obtained with an unstructured spatial model when an estimate of the DOAs is available. Exemplarily, simulation results for time-delay estimation for GPS (global positioning system) are included and confirm that our proposal approaches the Cramer-Rao lower bound (CRLB) of the structured model even when suboptimal DOA estimates obtained by ESPRIT are introduced.

关键词： Frequency estimation Direction of arrival estimation Global Positioning System Delay estimation Data models Sensor arrays signal processing Gaussian noise Aerospace engineering Navigation

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Face verification algorithm based on combination of modular 2DPCA and CSLDA

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Jisuanji Yanjiu yu Fazhan/computer Research and Development 2008年第6期45卷 1029-1035页

作者： Yuan, Ning Wu, Xiaojun Wang, Shitong Yang, Jingyu Kittler, Josef School of Information Engineering Jiangnan University Wuxi 214122 China School of Computer Science and Technology Nanjing University of Science and Technology Nanjing 210094 China Center for Vision Speech and Signal Processing Department of Electrical Engineering University of Surrey Surrey GU2 7XH United Kingdom

An improved face verification algorithm is proposed based on the combination of modular 2DPCA and CSLDA in this paper. Feature extraction of client specific linear discriminant analysis (CSLDA) transforms an image matrix to a vector which causes great dimensionality and computational complexity. Furthermore, the local feature is not considered in CSLDA. Then the new method is studied to avoid the deficiency. The initial features are extracted with the original images which are divided into modular sub-images. The 2DPCA is performed to get the low dimensional features which can be computed conveniently. The local features are extracted efficiently using the proposed new method. Then CSLDA is utilized on the new pattern which is obtained through the modular 2DPCA to extract the final features. Compared with PCA, the discriminant information obtained from the between-class scatter matrix and within-class scatter matrix are included using CSLDA. Moreover, client specific subspace could describe the diversity of the different face better and has more robust discriminant information than the traditional LDA. The experimental results obtained on the facial database XM2VTS using the Lausanne protocol and the facial database ORL using the user-defined protocol show that the verification performance of the new method is superior to that of the primary method CSLDA.

关键词： Feature extraction

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A shared-relay cooperative diversity scheme based on joint channel and network coding

A shared-relay cooperative diversity scheme based on joint c...

引用

International Symposium on Information Theory and Its Applications, ISITA

作者： Xiaoyan Xu Mark F. Flanagan Christian Koller Norbert Goertz Institute for Digital Communications Joint Research Institute for Signal & Image Processing University of Edinburgh UK Department of Electronics Computer Science and Systems (DEIS) University of Bologna Italy Department of Electrical Engineering University of Notre Dame Notre Dame IN USA

ISBN: (纸本)9781424420681

In cooperative communications, the technique of algebraic code superposition (or network coding) may efficiently utilize limited communications resources to produce spatial diversity. In this paper, we propose a simple cooperative diversity scheme for the scenario of two sources sharing a single relay. No cooperative coding is required at the sources, and only very simple interleave-and-superpose operations are performed at the relay. We propose a novel computationally efficient message passing algorithm at the destination's decoder which utilizes spatial diversity gathered over multiple transmission frames. We show that despite the simplicity of the proposed scheme, diversity gains are efficiently leveraged by the simple combination of channel coding at the sources and network coding at the relay.

关键词： Network coding Decoding Relays Parity check codes Electronic mail Fading Message passing Diversity methods Information theory Digital communication

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A Spectro-Temporal Algorithm for Pitch Frequency Estimation from Noisy Observations

A Spectro-Temporal Algorithm for Pitch Frequency Estimation ...

引用

2008 IEEE International Symposium on Circuits and Systems (ISCAS 2008), vol.5

作者： C. Shahnaz W.-P. Zhu M. O. Ahmad Centre for Signal Processing and Communications Department of Electrical and Computer Engineering Concordia University Montreal QUE Canada

A novel algorithm for pitch frequency (PF) estimation from non-stationary noise-corrupted speech observations is presented in this paper based on both spectral pre-processing and temporal representation. A modified power spectral subtraction based de-noising scheme that allows tracking the time-variation of the underlying non-stationary noise is put forward to enhance speech prior to PF estimation. The de-noised speech is then utilized to propose a squared difference function of the Linear Prediction (LP) residual which is expected to reveal more prominent dips at integral multiples of the pitch period compared to that revealed by the LP residual. The dips at different pitch-harmonic locations are added and weighted by a periodicity dependent weighting factor for every possible pitch period thus yielding a weighted and harmonically summed temporal function which is globally minimized to extract the desired PF. Simulation results using the Keele database show the superior efficacy of the proposed method in the presence of a multi-talker babble noise relative to some of the existing methods.

关键词： Frequency estimation Speech enhancement Noise reduction Speech analysis signal processing algorithms Personal digital assistants Degradation Additive noise signal to noise ratio Filters

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Semi-Blind Channel Estimation of MIMO-OFDM Systems with Pulse Shaping

Semi-Blind Channel Estimation of MIMO-OFDM Systems with Puls...

引用

2008 IEEE International Symposium on Circuits and Systems (ISCAS 2008), vol.1

作者： Feng Wan Wei-Ping Zhu M.N.S. Swamy Centre for Signal Processing and Communications Department of Electrical and Computer Engineering Concordia University Montreal QUE Canada

Most of the existing MIMO-OFDM channel estimation methods do not take into account the effect of the pulse-shaping filter in the transmitter nor of the matched filter in the receiver, thus leading to an estimation solution for the composite channel including the pulse-shaping and matched filters, instead of for the pure wireless channel. This solution is neither directly applicable to practical communication systems nor sufficiently accurate due to the extra length of the composite channel induced by the two filters. In this paper, a semi-blind channel estimation method is proposed for pulse-shaped MIMO-OFDM systems. By utilizing the knowledge of pulse-shaping and matched filters, a time domain semi-blind estimation method is developed for the pure multi-path channel. In order to reduce the computational burden of the time-domain algorithm, a frequency-domain alternative is derived. A number of computer simulation-based experimentations are conducted, and these simulations confirm the effectiveness of the proposed semi-blind method.

关键词： Channel estimation Pulse shaping methods Matched filters MIMO OFDM Transmitters Computational modeling computer simulation Wireless communication Receiving antennas

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A Lattice Structure for Linear-Phase Perfect Reconstruction Filter Banks with Mirror Image Symmetric Frequency Response

A Lattice Structure for Linear-Phase Perfect Reconstruction ...

引用

2008 IEEE International Symposium on Circuits and Systems (ISCAS 2008), vol.9

作者： Chao Wu Wei-Ping Zhu M.N.S. Swamy Centre for Signal Processing and Communications Department of Electrical and Computer Engineering Concordia University Montreal QUE Canada

In this paper, the lattice structure of a class of filter banks that possesses both the linear-phase property and the mirror-image symmetry, referred to as MIS-LPPRFB, has been investigated. By combining the MIS and the LP constraints and proposing a new simplified scheme, a reduced lattice structure with fewer parameters has been developed. It is shown that the introduction of the MIS has imposed certain constraints on the invertible matrices in the lattice structure of the conventional LPPRFBs, reducing the number of free parameters by nearly one-half. Using the new lattice structure, the optimization design problem of MIS-LPPRFBs is also addressed with an objective of achieving a high performance filter bank for its use in image compression coding.

关键词： Lattices Image reconstruction Filter bank Mirrors Frequency response Image coding Gallium nitride Chaotic communication signal processing Design optimization

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Perturbation Analysis of Subspace-Based Semi-Blind MIMO Channel Estimation Approaches

Perturbation Analysis of Subspace-Based Semi-Blind MIMO Chan...

引用

2008 IEEE International Symposium on Circuits and Systems (ISCAS 2008), vol.1

作者： Feng Wan Wei-Ping Zhu M.N.S. Swamy Centre for Signal Processing and Communications Department of Electrical and Computer Engineering Concordia University Montreal QUE Canada

In this paper, a perturbation analysis of two subspace-based semi-blind MIMO channel estimation approaches is conducted. Our analysis shows that, in the noise-free case, the whitening-rotation (WR)-based algorithm is subject to a signal perturbation error, while the nulling-based algorithm is a signal perturbation free scheme with an ideal nulling constraint imposed on the channel matrix. This explains why the WR-based method is efficient only in the low SNR case, and concludes that the nulling-based approach is better for moderate to high SNRs. A novel closed-form mean square error (MSE) expression is also derived for the nulling-based blind estimation method, in which an appealing scheme for the determination of the weighting factor is presented. The nulling-based method with the proposed weighting scheme is validated via computer simulations, showing a very high estimation accuracy of our semi-blind solution in terms of the MSE of the channel estimate.

关键词： MIMO Channel estimation signal processing algorithms signal analysis Mean square error methods Receiving antennas Algorithm design and analysis Maximum likelihood estimation Phase estimation computer errors

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