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Signal Processing Letters, IEEE

Issue 2 • Date Feb. 2005

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Displaying Results 1 - 25 of 27
  • Table of contents

    Publication Year: 2005 , Page(s): c1 - c4
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    Freely Available from IEEE
  • IEEE Signal Processing Letters publication information

    Publication Year: 2005 , Page(s): c2
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  • Eigenanalysis of autocorrelation matrices in the presence of noncentral and signal-dependent noise

    Publication Year: 2005 , Page(s): 85 - 88
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (169 KB)  

    We present approximations for eigenvalues of autocorrelation matrices in the presence of noncentral and signal-dependent noise as a function of eigenvalues of noiseless input. We derive error bounds for the approximations and discuss their properties. The results of the eigenanalysis are applied to the study of first-order polarization mode dispersion for optical systems. The simulation results demonstrate a good match between the approximated and true eigenvalues. View full abstract»

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  • Direct N-point DCT computation from three adjacent N/3-point DCT coefficients

    Publication Year: 2005 , Page(s): 89 - 92
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (166 KB)  

    An efficient method for computing a length-N Discrete Cosine Transform (DCT) from three consecutive length-N/3 DCTs is proposed. This method differs from previous ones in that it reduces considerable 31-38% arithmetic operations and uses only length-N/3 DCTs instead of length-N DCTs. We also find its great applications in fractional scaling of a block DCT-based image by the factor of 1/2/sup /spl alpha//3/sup /spl beta//. This would be very useful in high-definition television (HDTV) standard, whose display size is usually 16:9. The comparison with conventional methods is provided. View full abstract»

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  • A new SLM OFDM scheme with low complexity for PAPR reduction

    Publication Year: 2005 , Page(s): 93 - 96
    Cited by:  Papers (14)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (202 KB)  

    The authors introduce a new selected mapping (SLM) orthogonal frequency division multiplexing (OFDM) scheme with low computational complexity. The proposed SLM scheme transforms an input symbol sequence into a set of OFDM signals by multiplying the phase sequences to the signal after a certain intermediate stage of inverse fast Fourier transform (IFFT). Then, the OFDM signal with the lowest peak-to-average power ratio (PAPR) is selected for transmission. The new SLM OFDM scheme reduces the computational complexity, while it shows almost the same performance of PAPR reduction as that of the conventional SLM OFDM scheme. View full abstract»

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  • Recovering a compactly supported function from knowledge of its Hilbert transform on a finite interval

    Publication Year: 2005 , Page(s): 97 - 100
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    Inverting the finite Hilbert transform is a crucial step in some algorithms for tomographic imaging and signal processing. In this letter, a new method for inverting the finite Hilbert transform that requires data only on a finite interval is proposed. The new method is compared to the Jacobi-polynomial collocation method, which is employed for solving the airfoil integral equation, which is equivalent to inverting the finite Hilbert transform. Quantitative results show that the new method is more accurate and less susceptible to data noise than collocation and other methods. View full abstract»

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  • Lidar signal denoising using least-squares support vector machine

    Publication Year: 2005 , Page(s): 101 - 104
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (129 KB)  

    The noise in a Lidar signal is analyzed first, and then a novel method that applies least-square support vector machine (LS-SVM) to denoising Lidar signals is proposed. In order to improve the performance of denoising, the a priori knowledge about Lidar signals is also incorporated in the training of the LS-SVM. Finally, the experimental results demonstrate the effectiveness and efficiency of our approach. View full abstract»

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  • An algorithm for optimal partitioning of data on an interval

    Publication Year: 2005 , Page(s): 105 - 108
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (112 KB)  

    Many signal processing problems can be solved by maximizing the fitness of a segmented model over all possible partitions of the data interval. This letter describes a simple but powerful algorithm that searches the exponentially large space of partitions of N data points in time O(N/sup 2/). The algorithm is guaranteed to find the exact global optimum, automatically determines the model order (the number of segments), has a convenient real-time mode, can be extended to higher dimensional data spaces, and solves a surprising variety of problems in signal detection and characterization, density estimation, cluster analysis, and classification. View full abstract»

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  • A comment on "Estimating the standard deviation from extreme Gaussian values"

    Publication Year: 2005 , Page(s): 109 - 111
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    This letter relates to a paper (Stark and Brankov, IEEE Signal Process. Lett., vol.11, no.3, p.320-2, March 2004) that used extreme Gaussian values to estimate the standard deviation. We show that the estimator given in the aforementioned paper is a special case of relevant ones previously obtained in the literature about which the authors are unaware. Also, some slight errors in the paper are pointed out and corrected. View full abstract»

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  • On the multidimensional extension of the quincunx subsampling matrix

    Publication Year: 2005 , Page(s): 112 - 115
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (214 KB)  

    The dilation matrix associated with the three-dimensional (3-D) face-centered cubic (FCC) sublattice is often considered to be the natural 3-D extension of the two-dimensional (2-D) quincunx dilation matrix. However, we demonstrate that both dilation matrices are of different nature: while the 2-D quincunx matrix is a similarity transform, the 3-D FCC matrix is not. More generally, we show that is impossible to obtain a dilation matrix that is a similarity transform and performs downsampling of the Cartesian lattice by a factor of two in more than two dimensions. Furthermore, we observe that the popular 3-D FCC subsampling scheme alternates between three different lattices: Cartesian, FCC, and quincunx. The latter one provides a less isotropic sampling density, a property that should be taken into account to properly orient 3-D data before processing using such a subsampling matrix. View full abstract»

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  • A two-channel nonuniform perfect reconstruction filter Bank with irrational down-sampling factors

    Publication Year: 2005 , Page(s): 116 - 119
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (352 KB)  

    Most of the existing methods designed to implement fractional interpolation and decimation are limited by rational scaling factors such as L/M, where L and M are positive integers. The general procedure is usually done with up-sampling by L first, and then followed by down-sampling by M. This scheme, however, requires two steps and higher sampling rates to fulfill and is not capable in dealing with irrational scaling factors, which cannot be represented by L/M. We propose a new method to solve the above two difficulties by a single step. Furthermore, a new structure of a two-channel nonuniform perfect reconstruction filter bank is derived using this new method, and the experimental results are presented. View full abstract»

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  • Efficient lifting wavelet transform for microprocessor and VLSI applications

    Publication Year: 2005 , Page(s): 120 - 122
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (143 KB)  

    Recently, wavelet analysis has gained an established role in signal and image processing applications. In this paper, we present a discrete wavelet transform algorithm based on the lifting scheme. The Haar wavelet transformed and decimated signals are lifted by the ladder-type network. A unique lifting filter is designed for in-place computation. The present algorithm is especially suitable for microprocessor and VLSI applications since it can be implemented by integer arithmetics using only register shifts and summations. View full abstract»

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  • Spatiotemporal-bandwidth product of m-dimensional signals

    Publication Year: 2005 , Page(s): 123 - 125
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    A system-theoretic proof for the spatiotemporal-bandwidth product (STBP) of multidimensional signals is given. Explicit formulae for the STBP of multivariate Gaussian signals and their derivatives are also supplied. View full abstract»

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  • Spatial filter-based absorbing boundary for the 2-D digital waveguide mesh

    Publication Year: 2005 , Page(s): 126 - 129
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    The digital waveguide mesh is a method for simulating wave propagation, for example, in an acoustic system. Research on the boundary conditions has been going on for years, but adequate solutions for absorbing boundaries have not yet been presented for the digital waveguide mesh. In this work, a new method for constructing absorbing boundaries for a two-dimensional (2-D) rectangular mesh is introduced. With the use of the proposed numerically optimized spatial filtering with an interpolated mesh structure, the reflection was diminished to under -25 dB at incidence angles |/spl theta/|/spl les/79.26/spl deg/ on a frequency band limited only at the very lowest and highest ends. View full abstract»

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  • Closed-loop transmit diversity schemes for five and six transmit antennas

    Publication Year: 2005 , Page(s): 130 - 133
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    Closed-loop, rate-one, channel orthogonalized space-time block codes (CO-STBCs) for three and four transmit antennas using a single (real) phase feedback term have been proposed . These codes achieve full diversity and result in maximum likelihood (ML) decoding with only linear processing at the receiver similar to OSTBCs. In this paper, we propose a closed-loop STBC for five and six transmit antennas with rate 3/4, where the one parameter feedback angle can be evaluated in closed form. These codes achieve full diversity and are delay optimal. Simulation results comparing the error-rate performance of the CO-STBC with open-loop OSTBC as well as some quasiorthogonal space-time block codes are also provided. While the 1- to 5-dB gain accrued by the closed-loop scheme (over the open-loop methods) is not surprising, the novel contribution of this work is in the approach taken to derive the feedback parameter as a single phase term, which is purely a function of the channel gains. View full abstract»

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  • Application of STBC-encoded cooperative transmissions in wireless sensor networks

    Publication Year: 2005 , Page(s): 134 - 137
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (149 KB)  

    The efficiency of space-time block code-encoded (STBC) cooperative transmission is studied within low-energy adaptive clustering hierarchy (LEACH), which is a typical networking/communication protocol for wireless sensor networks. Cooperation protocol with low overhead is proposed, and synchronization requirements among cooperating sensors are discussed. Energy efficiency is analyzed as a tradeoff between the reduced transmission energy consumption and the increased electronic and overhead energy consumption. Simulations show that with proper design, cooperative transmission can enhance energy efficiency and prolong sensor network lifetime. View full abstract»

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  • Low-complexity lossless compression of hyperspectral imagery via linear prediction

    Publication Year: 2005 , Page(s): 138 - 141
    Cited by:  Papers (2)  |  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (453 KB)  

    We present a new low-complexity algorithm for hyperspectral image compression that uses linear prediction in the spectral domain. We introduce a simple heuristic to estimate the performance of the linear predictor from a pixel spatial context and a context modeling mechanism with one-band look-ahead capability, which improves the overall compression with marginal usage of additional memory. The proposed method is suitable to spacecraft on-board implementation, where limited hardware and low power consumption are key requirements. Finally, we present a least-squares optimized linear prediction technique that achieves better compression on data cubes acquired by the NASA JPL Airborne Visible/Infrared Imaging Spectrometer (AVIRIS). View full abstract»

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  • Robust stability of 2-D digital filters employing saturation

    Publication Year: 2005 , Page(s): 142 - 145
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (151 KB) |  | HTML iconHTML  

    A computationally tractable, i.e., linear matrix inequality (LMI)-based criterion for the global asymptotic stability of uncertain two-dimensional digital filters described by the Fornasini-Marchesini second local state-space model with saturation overflow arithmetic is presented. The criterion is compared with an earlier LMI-based criterion. View full abstract»

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  • Improved update operators for lifting-based motion-compensated temporal filtering

    Publication Year: 2005 , Page(s): 146 - 149
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (163 KB)  

    Motion-compensated temporal filtering (MCTF) is an essential ingredient of the recently developed wavelet-based scalable video coding schemes. Lifting implementation of these decompositions represents a versatile tool for spatiotemporal optimizations, and several improvements have already been proposed in this framework. In this paper, we propose new spatiotemporal update operators based either on weighted averages of multiple connected pixels or on nonlinear filtering of these pixels. We demonstrate the improved performance of the proposed operators, both theoretically and experimentally. View full abstract»

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  • Optimum update for motion-compensated lifting

    Publication Year: 2005 , Page(s): 150 - 153
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (157 KB)  

    In wavelet video coding with motion-compensated lifting, the update step typically reverses the motion vectors from the prediction step. Where motion compensation is not invertible, heuristic rules are used for the update step. This paper derives a closed-form expression for the optimal update step for a given general linear prediction step and applies the result to motion-compensated wavelet coding. The analysis justifies using reversed motion vectors, where possible, and yields new results on proper inversion of subpixel motion compensation and optimal treatment of motion discontinuities. A new sparse matrix technique is presented that allows the practical implementation of the optimal update step for motion-compensated wavelet video coding. Experimental results confirm that optimizing the update step improves the rate-distortion performance for a motion-compensated wavelet video coder and provide justification for heuristics used in conventional techniques. View full abstract»

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  • Robust layered multiple description coding of scalable media data for multicast

    Publication Year: 2005 , Page(s): 154 - 157
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (229 KB)  

    Layered multiple description codes allow robust transmission of scalable media data over packet erasure networks, while providing simple rate adaptation and bandwidth savings for shared bottleneck links. We show how to efficiently design layered multiple description codes for multicast and broadcast applications in memoryless packet erasure networks. Our approach offers a significantly better quality tradeoff among clients than the best previous solution. View full abstract»

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  • Effectiveness of exhaustive search and template matching against watermark desynchronization

    Publication Year: 2005 , Page(s): 158 - 161
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (164 KB)  

    By focusing on a simple example, we investigate the effectiveness of exhaustive watermark detection and resynchronization through template matching against watermark desynchronization. We find that if the size of the search space does not increase exponentially, both methods provide asymptotically good results. We also show that the exhaustive search approach outperforms template matching from the point of view of reliable detection. View full abstract»

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  • Adaptive cochannel interference suppression based on subarrays for HFSWR

    Publication Year: 2005 , Page(s): 162 - 165
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (467 KB)  

    The paper analyzes the characteristics of cochannel interference (CCI) in the high-frequency (HF) surface wave radar (HFSWR), which adopts the linear frequency modulated interrupted continuous wave (FMICW). CCI will influence all the range bins, including all the positive and negative frequencies, and the negative frequency range bins contain only the external interference information. Based on the above characteristics, we introduce a new adaptive coherent side-lobe cancellation (CSLC) algorithm based on subarrays that use the negative frequency range bin samples to estimate the interference covariance matrix and correlation vector. Experimental results confirm that the general and robust algorithm can achieve effective CCI suppression using the data recorded by the Ocean State Monitor and Analysis Radar (OSMAR2003, manufactured in 2003), located near Zhoushan in Zhejiang, China. View full abstract»

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  • Revisiting autoregressive hidden Markov modeling of speech signals

    Publication Year: 2005 , Page(s): 166 - 169
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (144 KB)  

    Linear predictive hidden Markov modeling is compared with a simple form of the switching autoregressive process. The latter process captures existing signal correlation during transitions of the Markov chain. Parameter estimation is described using naturally stable forward-backward recursions. The switching autoregressive model outperformed the linear predictive model in a digit recognition task and provided comparable performance to a cepstral-based recognizer. View full abstract»

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  • IEEE Signal Processing Letters Information for authors

    Publication Year: 2005 , Page(s): 170 - 171
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    Freely Available from IEEE

Aims & Scope

The IEEE Signal Processing Letters is a monthly, archival publication designed to provide rapid dissemination of original, cutting-edge ideas and timely, significant contributions in signal, image, speech, language and audio processing.

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Peter Willett
University of Connecticut
Storrs, CT 06269
peter.willett@uconn.edu