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Conference on advanced signal processing algorithms, architectures, and implementations VI

作者： Luk, FT Qiao, SZ RENSSELAER POLYTECH INST DEPT COMP SCITROYNY 12180

ISBN: (纸本)0819422347

In array processing, one technique for cancelling interference in the presence of colored noise is the ULLV decomposition of a pair of matrices. The factorization is stable and accurate, and is easy to update when a row is added to either one of the two matrices. In earlier work, we made the assumptions that both matrices must have at least as many rows as columns and that the matrix representing interference must have full column rank. In this paper, we relax the latter restriction and allow the interference matrix to be rank deficient. We present an algorithm for computing the decomposition and two techniques for updating it. The details on updating are quite different from those in the full rank case. © 1996 SPIE. All rights reserved.

关键词： ULLV decomposition matrix updating noise subspace tracking

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INSTANTANEOUS FREQUENCY AND KERNEL REQUIREMENTS FOR DISCRETE TIME-FREQUENCY DISTRIBUTIONS

INSTANTANEOUS FREQUENCY AND KERNEL REQUIREMENTS FOR DISCRETE...

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CONF ON advanced signal-processing algorithms, architectures, AND implementations

作者： JEONG, JH CUNNINGHAM, GS WILLIAMS, WJ Univ. of Michigan (United States)

ISBN: (纸本)0819404098

In this paper we introduce a new definition for the instantaneous frequency of a discrete-time analytic signal. Unlike the existing definition which uses only two data samples around a particular time this method utilizes all the data samples for estimating the instantaneous frequency. We prove that this quantity is identical to the average frequency evaluated at the particular time in the discrete-time TFD. This property is consistent with the analogous continuous-time property. We also derive requirements on the discrete-time kernel needed to satisfy this property. Using computer-generated signals and real data performance comparisons are made between the proposed approach and the existing one.

关键词： Time-frequency analysis Data analysis signal analyzers Statistical analysis

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Fast blind signal separation for multi-user interference rejection in smart antenna arrays

Fast blind signal separation for multi-user interference rej...

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Conference on advanced signal processing - algorithms, architectures, and implementations Vii

作者： Sarajedini, A Chau, PM Univ. of California/San Diego (United States)

ISBN: (纸本)0819425842

Spread spectrum modulation techniques such as frequency-hopped code division multiple access (FH-CDMA) are an efficient way to allow multi-user transmission over a limited bandwidth. Recently, there has been a push to increase user capacity over the same bandwidth. In particular, smart antenna arrays have been studied for their capacity gain potential. In this regard, we propose the use of blind signal separation for recovery of signals received through an antenna array. To implement this technique requires the antenna array vectors to be stationary which does not hold in FH-CDMA, so we also propose a new method for frequency compensation. We present the theoretical details of the frequency compensation and compare its performance to no frequency compensation. We then present the blind signal separation algorithm applied to a complex antenna array matrix and complex signals with noise and show in simulation that the blind signal separation works.

关键词： blind signal separation frequency compensation frequency-hopped CDMA spread spectrum

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NInFEA: an embedded framework for the real-time evaluation of fetal ECG extraction algorithms

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BIOMEDICAL ENGINEERING-BIOMEDIZINISCHE TECHNIK 2013年第1期58卷 13-26页

作者： Pani, Danilo Barabino, Gianluca Raffo, Luigi Univ Cagliari Dept Elect & Elect Engn DIEE I-09123 Cagliari Italy

Fetal electrocardiogram (ECG) extraction from non-invasive biopotential recordings is a long-standing research topic. Despite the significant number of algorithms presented in the scientific literature, it is difficult to find information about embedded hardware implementations able to provide real-time support for the required features, bridging the gap between theory and practice. This article presents the NInFEA (non-invasive fetal ECG analysis) tool, an embedded hardware/software framework based on the hybrid dual-core OMAP-L137 low-power processor for the real-time evaluation of fetal ECG extraction algorithms. The hybrid platform, including a digital signal processor (DSP) and a general-purpose processor (GPP), allows achieving the best performance compared with single-core architectures. The GPP provides a portable graphical user interface, whereas the DSP is extensively used for advanced signal processing tasks. As a case study, three state-of-the-art fetal ECG extraction algorithms have been ported onto NInFEA, along with some support routines needed to provide the additional information required by the clinicians and supported by the user interface. NInFEA can be regarded both as a reference design for similar applications and as a common embedded low-power testbed for real-time fetal ECG extraction algorithms.

关键词： biomedical signal processing DSP platforms non-invasive fetal ECG real-time processing

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New algorithms for on-line computation of elementary functions

New algorithms for on-line computation of elementary functio...

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advanced signal processing algorithms, architectures, and implementations ii

作者： Kla, Sylvanus Mazenc, Christophe Merrheim, Xavier Muller, Jean-Michel M. Ecole Normale Superieure de Lyon Lyon Cedex 07 France

ISBN: (纸本)0819406945

We present here some algorithms for on-line computation of elementary functions. These algorithms use shift-and-add as elementary step and need signed digit representations of numbers. Then, we give some theoretical results about on-line computation of functions. For instance, we show that a finite automaton (in practice a bounded size and memory operator) can compute in on-line only piecewise affine functions.

关键词： signal processing

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IMPLEMENTING THE VITERBI ALGORITHM ON GENERAL-PURPOSE PARALLEL COMPUTERS

IMPLEMENTING THE VITERBI ALGORITHM ON GENERAL-PURPOSE PARALL...

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CONF ON advanced signal processing algorithms, architectures, AND implementations 3

作者： ALSTON, MD CHAU, PM CHEUNG, KM Univ. of California/San Diego (United States) Jet Propulsion Lab. (United States)

ISBN: (纸本)081940943X

The Viterbi algorithm (VA) for decoding convolutionally encoded data has historically been implemented on special-purpose digital electronic hardware. For short/moderate (K equals 3 to 9) constraint length codes, a primary design goal is to maximize the decoded bit rate while minimizing circuit area. In recent years, a number of special-purpose architectures based upon shuffle-exchange networks, cube-connected cycles, ring-based networks, systolic arrays, or programmable processors have been designed for efficient implementation of the VA at these and longer constraint lengths. However, at the same time, the performance:cost ratio of high- end general-purpose computing machines has been improving dramatically. Recognizing the substantial investment in time and resources required to design and build an ASIC-based decoder for long (K equals 10 to 15) constraint length codes, the feasibility of implementation of the VA as a background process on a readily available general-purpose parallel processing machine deserves exploration. We consider the limitations and benefits of a Viterbi decoder for long constraint length codes implemented in software on a general-purpose parallel processing machine.

关键词： Computing systems Parallel processing Binary data Telecommunications Computer programming Forward error correction Network architectures Parallel computing signal processing Very large scale integration

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TIME-RECURSIVE COMPUTATION AND REAL-TIME PARALLEL architectures, WITH APPLICATION ON THE MODULATED LAPPED TRANSFORM 4

TIME-RECURSIVE COMPUTATION AND REAL-TIME PARALLEL ARCHITECTU...

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4TH CONF ON advanced signal processing algorithms, architectures, AND implementations

作者： FRANTZESKAKIS, E BARAS, JS LIU, KJR Univ. of Maryland/College Park (United States)

ISBN: (纸本)0819412767

In this paper, we establish an architectural framework for parallel time-recursive computation. We consider a class of linear operators that consists of the discrete time, time invariant, compactly supported, but otherwise arbitrary kernel functions. We specify the properties of the linear operators that can be implemented efficiently in a time-recursive way. Based on these properties, we develop a routine that produces a time-recursive architectural implementation for a given operator. This routine is instructive for the design of a CAD tool that will facilitate the architecture derivation. Using this background, we design an architecture for the Modulated Lapped Transform (commonly called Modified Discrete Cosine Transform), which has linear cost in operator counts.

关键词： Modulation Computer aided design Computer architecture Fourier transforms Convolution Digital filtering Very large scale integration Radar Video Video processing

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Performance of space-frequency codes for MIMO OFDM systems

Performance of space-frequency codes for MIMO OFDM systems

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Conference on advanced signal processing algorithms architectures and implementations XiiI

作者： Wang, JB Yao, K Univ Calif Los Angeles Dept Elect Engn Los Angeles CA 90095 USA

ISBN: (纸本)0819450782

Concatenation of space-time (ST) coding with orthogonal frequency-division multiplexing (OFDM) has gained much interest recently. In this work, we derive the exact pairwise error probability (PEP) of space-frequency (SF) codes for MIMO OFDM Systems. Based on the exact PEP, we derive the tighter upper and lower bounds for the PEP. For asymptotically high SNRs, the design criteria for SF codes differ significantly from those for ST codes over flat fading channels. In this paper, by drawing an analogy between SF and ST codes, we show that when the number of receive antennas is large, the minimum Euclidean distance among code words dominates the performance of SF codes. Therefore, SF codes can be optimized by using the Euclidean-distance criterion valid for AWGN channels. Simulation results are given to show that the results valid for a number of receive antennas tending to infinity still provide correct indications when the number of antennas is small.

关键词： Orthogonal frequency division multiplexing Antennas Modulation Lutetium signal to noise ratio Computer simulations Demodulation signal processing

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Approximation by structured lower rank matrices

Approximation by structured lower rank matrices

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SPIE Conference on advanced signal processing algorithms, architectures, and implementations ViiI

作者： Chu, MT Funderlic, RE Plemmons, RJ N Carolina State Univ Dept Math Raleigh NC 27695 USA

ISBN: (纸本)0819429163

We consider two general procedures for constructing the nearest approximation of a given matrix by one with any lower rank and any linear structure. Nearness can be measured in any matrix norm. Structured low rank matrices arise in various applications, including image enhancement and model reduction. In practice, the empirical data collected in the matrix often either do not maintain the specified structure or do not induce the desirable rank. It is an important task to search for the nearest structured lower rank approximation of a given matrix. The techniques developed in this paper can easily be implemented for numerical computation. In particular, it is shown that the computations can be approached using efficient optimization packages. The special case of Toeplitz structure using the Frobenius matrix norm is discussed in detail to illustrate the ideas, and numerical tests are reported. The procedures developed herein can be generalized to consider a much broader range of approximation problems.

关键词： Matrices signal processing MATLAB Optimization (mathematics) Image enhancement Computer programming Computer science Fourier transforms Image processing Mathematics

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RECURSIVE LEAST-SQUARES LEARNING algorithms FOR NEURAL NETWORKS

RECURSIVE LEAST-SQUARES LEARNING ALGORITHMS FOR NEURAL NETWO...

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CONF ON advanced signal-processing algorithms, architectures, AND implementations

作者： LEWIS, PS HWANG, JN Los Alamos National Lab. (United States) Univ. of Washington (United States)

ISBN: (纸本)0819404098

This paper presents the development of a pair of recursive least squares (ItLS) algorithms for online training of multilayer perceptrons which are a class of feedforward artificial neural networks. These algorithms incorporate second order information about the training error surface in order to achieve faster learning rates than are possible using first order gradient descent algorithms such as the generalized delta rule. A least squares formulation is derived from a linearization of the training error function. Individual training pattern errors are linearized about the network parameters that were in effect when the pattern was presented. This permits the recursive solution of the least squares approximation either via conventional RLS recursions or by recursive QR decomposition-based techniques. The computational complexity of the update is 0(N2) where N is the number of network parameters. This is due to the estimation of the N x N inverse Hessian matrix. Less computationally intensive approximations of the ilLS algorithms can be easily derived by using only block diagonal elements of this matrix thereby partitioning the learning into independent sets. A simulation example is presented in which a neural network is trained to approximate a two dimensional Gaussian bump. In this example RLS training required an order of magnitude fewer iterations on average (527) than did training with the generalized delta rule (6 1 BACKGROUND Artificial neural networks (ANNs) offer an interesting and potentially useful paradigm for signal processing and pattern recognition. The majority of ANN applications employ the feed-forward multilayer perceptron (MLP) network architecture in which network parameters are " trained" by a supervised learning algorithm employing the generalized delta rule (GDIt) [1 2]. The GDR algorithm approximates a fixed step steepest descent algorithm using derivatives computed by error backpropagatiori. The GDii algorithm is sometimes referred to as the

关键词： Algorithm development Detection and tracking algorithms Evolutionary algorithms Neural networks Network architectures Artificial neural networks Pattern recognition Chemical elements Machine learning signal processing

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