IEEE Signal Processing Letters

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 de... View full abstract»

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 ... View full abstract»

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-t... View full abstract»

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 equiv... View full abstract»

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 ... View full abstract»

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 (th... View full abstract»

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 poi... View full abstract»

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... View full abstract»

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 wit... View full abstract»

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 mi... View full abstract»

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»

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 introd... View full abstract»

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 ante... View full abstract»

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... View full abstract»

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 pr... View full abstract»

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»

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... View full abstract»

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 codi... View full abstract»

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 qual... View full abstract»

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... View full abstract»

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 th... View full abstract»

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 a... View full abstract»