By Topic

Signal Processing Letters, IEEE

Issue 7 • Date July 2006

Filter Results

Displaying Results 1 - 21 of 21
  • Table of contents

    Publication Year: 2006 , Page(s): c1 - c4
    Save to Project icon | Request Permissions | PDF file iconPDF (37 KB)  
    Freely Available from IEEE
  • IEEE Signal Processing Letters publication information

    Publication Year: 2006 , Page(s): c2
    Save to Project icon | Request Permissions | PDF file iconPDF (38 KB)  
    Freely Available from IEEE
  • Amplitude modulated sinusoidal signal decomposition for audio coding

    Publication Year: 2006 , Page(s): 389 - 392
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (161 KB) |  | HTML iconHTML  

    In this letter, we present a decomposition for sinusoidal coding of audio, based on an amplitude modulation of sinusoids via a linear combination of arbitrary basis vectors. The proposed method, which incorporates a perceptual distortion measure, is based on a relaxation of a nonlinear least-squares minimization. Rate-distortion curves and listening tests show that, compared to a constant-amplitude sinusoidal coder, the proposed decomposition offers perceptually significant improvements in critical transient signals View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Improved information outage rate in certain MIMO systems

    Publication Year: 2006 , Page(s): 393 - 396
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (153 KB) |  | HTML iconHTML  

    We propose a simple class of encoding/decoding techniques that can be used to improve the information outage rate of certain multiple-input-multiple-output (MIMO) systems. Gains in outage rate can be achieved at low to moderate signal-to-noise ratios in MIMO systems that have fewer receive antennas than transmit antennas. This performance improvement is due to extra "virtual" receive antennas that are created with low-complexity signal processing. A simple space-time block code system using virtual receive antennas is also investigated View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Support vector machines for robust channel estimation in OFDM

    Publication Year: 2006 , Page(s): 397 - 400
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (242 KB) |  | HTML iconHTML  

    A new support vector machine (SVM) algorithm for coherent robust demodulation in orthogonal frequency-division multiplexing (OFDM) systems is proposed. We present a complex regression SVM formulation specifically adapted to a pilots-based OFDM signal. This novel proposal provides a simpler scheme than an SVM classification method. The feasibility of our approach is substantiated by computer simulation results obtained for IEEE 802.16 broadband fixed wireless channel models. These experiments allow to scrutinize the performance of the OFDM-SVM system and the suitability of the epsiv-Huber cost function, in the presence of non-Gaussian impulse noise interfering with OFDM pilot symbols View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Extreme Filters-cache-efficient implementation of long IIR and FIR filters

    Publication Year: 2006 , Page(s): 401 - 404
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (176 KB) |  | HTML iconHTML  

    Modern general purpose processors have powerful vector processing units that can be used in infinite impulse response and finite impulse response filtering in real time. In practice, the calculations are efficient only if the filter parameters fit into the processor's cache. With long filters, the computation is slowed down since the filter data do not fit into the cache at once. By computing the filter in multiple segments, more efficient cache utilization can be achieved. The presented optimization method works when multiple samples are processed in row. The improved cache efficiency increases performance by up to almost one magnitude over direct filter implementation on modern hardware View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Closed-form design of maximally flat FIR fractional delay filters

    Publication Year: 2006 , Page(s): 405 - 408
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (266 KB) |  | HTML iconHTML  

    Eight types of maximally flat finite impulse response (FIR) fractional delay filters are proposed. They are designed by separately approximating the real part and the imaginary part of the frequency response. Among these eight types of filters, two of them are equivalent to the existing design results in the open literature. Therefore, a more general closed-form design of the maximally flat FIR fractional delay filters is described in this letter, and some design examples of FIR fractional delay filters will be illustrated View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Morphological diversity and source separation

    Publication Year: 2006 , Page(s): 409 - 412
    Cited by:  Papers (14)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (584 KB) |  | HTML iconHTML  

    This letter describes a new method for blind source separation, adapted to the case of sources having different morphologies. We show that such morphological diversity leads to a new and very efficient separation method, even in the presence of noise. The algorithm, coined multichannel morphological component analysis (MMCA), is an extension of the morphological component analysis (MCA) method. The latter takes advantage of the sparse representation of structured data in large overcomplete dictionaries to separate features in the data based on their morphology. MCA has been shown to be an efficient technique in such problems as separating an image into texture and piecewise smooth parts or for inpainting applications. The proposed extension, MMCA, extends the above for multichannel data, achieving a better source separation in those circumstances. Furthermore, the new algorithm can efficiently achieve good separation in a noisy context where standard independent component analysis methods fail. The efficiency of the proposed scheme is confirmed in numerical experiments View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • An efficient detail-preserving approach for removing impulse noise in images

    Publication Year: 2006 , Page(s): 413 - 416
    Cited by:  Papers (53)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (422 KB) |  | HTML iconHTML  

    In this letter, we present a new efficient algorithm for the removal of impulse noise from corrupted images while preserving image details. The algorithm is based on the alpha-trimmed mean, which is a special case of the order-statistics filter. However, unlike some of the previous techniques involving order-statistics filters, the proposed method uses the alpha-trimmed mean only in impulse noise detection instead of pixel value estimation. Once a noisy pixel is identified, its value is replaced by a linear combination of its original value and the median of its local window. Extensive computer simulations indicate that our algorithm provides a significant improvement over many other existing techniques View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Three-directional box-splines: characterization and efficient evaluation

    Publication Year: 2006 , Page(s): 417 - 420
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (311 KB) |  | HTML iconHTML  

    We propose a new characterization of three-directional box-splines, which are well adapted for interpolation and approximation on hexagonal lattices. Inspired by a construction already applied with success for exponential splines and hex-splines, we characterize a box-spline as a convolution of a generating function, which is a Green function of the spline's associated differential operator, and a discrete filter that plays the role of a localization operator. This process leads to an elegant analytical expression of three-directional box-splines. It also brings along a particularly efficient implementation View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A simple framework for spatio-temporal video segmentation and delayering using dense motion fields

    Publication Year: 2006 , Page(s): 421 - 424
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (610 KB) |  | HTML iconHTML  

    To represent object movement, the conventional approach is to embed the motion information into parametric and/or statistical motion models. However, the inherent complexity of this description is ill suited for application requiring rapid and automatic, albeit significant, responses. Surveillance applications belong to this class and are emerging as the most active field of research in computer vision. For this purpose, we observe that the differential invariants obtained by dense optic flow are capable of accurately describing complex object motion without requiring setting up and initializing models. In this letter, we demonstrate the novel use of such motion descriptors for spatio-temporal object segmentation and delayering of sequences. Our results show the ability of this approach to describe simply and accurately differently moving objects and to be incorporated in segmentation processes that deliver a hierarchical description of object, producing evident improvements to the segmented objects while being computationally efficient View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • New multimodulus blind equalization algorithm with relaxation

    Publication Year: 2006 , Page(s): 425 - 428
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (277 KB) |  | HTML iconHTML  

    A new multimodulus algorithm is presented for blind equalization of complex-valued communication channels. The proposed algorithm is obtained by solving a novel deterministic optimization criterion that constituted the dispersion minimization of a priori as well as a posteriori quantities, leading to an update equation having a particular zero-memory continuous nonlinearity. Analyses of automatic phase-recovery and interference cancellation capabilities of the proposed algorithm are provided View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A novel algorithm for the adaptation of the pole of Laguerre filters

    Publication Year: 2006 , Page(s): 429 - 432
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (285 KB) |  | HTML iconHTML  

    This letter proposes a novel stochastic gradient algorithm for the online adaptation of the pole position in Laguerre filters. The proposed algorithm exploits the inherent relationship between the values of the filter coefficients and the value of the Laguerre pole. This leads to an unbiased solution and, hence, a more accurate estimate of the error gradient. Simulations in a system identification setting support the analysis View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A generalized likelihood ratio test for impropriety of complex signals

    Publication Year: 2006 , Page(s): 433 - 436
    Cited by:  Papers (30)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (137 KB) |  | HTML iconHTML  

    A complex random vector is called improper if it is correlated with its complex conjugate. We present a hypothesis test for impropriety based on a generalized likelihood ratio (GLR). This GLR is invariant to linear transformations on the data, including rotation and scaling, because propriety is preserved by linear transformations. More specifically, we show that the GLR is a function of the squared canonical correlations between the data and their complex conjugate. These canonical correlations make up a complete, or maximal, set of invariants for the Hermitian and complementary covariance matrices under linear, but not widely linear, transformation View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Mate/spl acute/rn B-splines and the optimal reconstruction of signals

    Publication Year: 2006 , Page(s): 437 - 440
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (244 KB) |  | HTML iconHTML  

    Starting from the power spectral density of Mateacutern stochastic processes, we introduce a new family of splines that is defined in terms of the whitening operator of such processes. We show that these Mateacutern splines admit a stable representation in a B-spline-like basis. We specify the Mateacutern B-splines (causal and symmetric) and identify their key properties; in particular, we prove that these generate a Riesz basis and that they can be written as a product of an exponential with a fractional polynomial B-spline. We also indicate how these new functions bridge the gap between the fractional polynomial splines and the cardinal exponential ones. We then show that these splines provide the optimal reconstruction space for the minimum mean-squared error estimation of Mateacutern signals from their noisy samples. We also propose a digital Wiener-filter-like algorithm for the efficient determination of the optimal B-spline coefficients View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Sparse linear regression in unions of bases via Bayesian variable selection

    Publication Year: 2006 , Page(s): 441 - 444
    Cited by:  Papers (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (216 KB) |  | HTML iconHTML  

    In this letter, we propose an approach for sparse linear regression in unions of bases inspired by Bayesian variable selection. Conditionally upon an indicator variable that is 0 or 1, one expansion coefficient of the signal corresponding to one atom of the dictionary is either set to zero or given a Student t prior. A Gibbs sampler (a standard Markov chain Monte Carlo technique) is used to sample from the posterior distribution of the indicator variables, the expansion coefficients (corresponding to nonzero indicator variables), the hyperparameters of the Student t priors, and the variance of the residual signal. The structure of the dictionary, assumed to be a union of bases, allows for alternate sampling of the indicator variables and the expansion coefficients from each basis and avoids any large matrix inversion. Our method is applied to the denoising problem of a piano sequence, using a dual-resolution union of two modified discrete cosine transform bases View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Neural network-aided adaptive unscented Kalman filter for nonlinear state estimation

    Publication Year: 2006 , Page(s): 445 - 448
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (204 KB) |  | HTML iconHTML  

    The extended Kalman filter (EKF) is well known as a state estimation method for a nonlinear system and has been used to train a multilayered neural network (MNN) by augmenting the state with unknown connecting weights. However, EKF has the inherent drawbacks such as instability due to linearization and costly calculation of Jacobian matrices, and its performance degrades greatly, especially when the nonlinearity is severe. In this letter, first a more robust learning algorithm for an MNN-based on unscented Kalman filter (UKF) is derived. Since it gives a more accurate estimate of the linkweights, the convergence performance is improved. The algorithm is then extended further to develop a NN-aided UKF for nonlinear state estimation. The NN in this algorithm is used to approximate the uncertainty of the system model due to mismodeling, extreme nonlinearities, etc. The UKF is used for both NN online training and state estimation simultaneously. Simulation results show that the new algorithm is very effective and is closer to optimal fashion in nonlinear filtering compared with traditional methods View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • IEEE Signal Processing Letters Information for authors

    Publication Year: 2006 , Page(s): 449 - 450
    Save to Project icon | Request Permissions | PDF file iconPDF (57 KB)  
    Freely Available from IEEE
  • 2007 IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP)

    Publication Year: 2006 , Page(s): 451
    Save to Project icon | Request Permissions | PDF file iconPDF (563 KB)  
    Freely Available from IEEE
  • Call for papers on network-aware multimedia processing and communications

    Publication Year: 2006 , Page(s): 452
    Save to Project icon | Request Permissions | PDF file iconPDF (158 KB)  
    Freely Available from IEEE
  • IEEE Signal Processing Society Information

    Publication Year: 2006 , Page(s): c3
    Save to Project icon | Request Permissions | PDF file iconPDF (32 KB)  
    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