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Adaptive decision fusion for unequiprobable sources

IEE PROCEEDINGS-RADAR SONAR AND NAVIGATION 1997年第3期144卷 105-111页

作者： Ansari, N Chen, JG Zhang, YZ Electrical and Computer Engineering Department Center for Communications and Signal Processing New Jersey Institute of Technology Newark USA

An optimal decision rule has been derived by Chair and Varshney (1986) for fusing decisions based on the Bayesian criterion. However, to implement such a rule, the miss probability P-M and the probability of false alarm P-F for each local detector must be known, and these are not readily available in practice. To circumvent this situation, an adaptive fusion system for equiprobable sources has been developed. The system is extended to unequiprobable sources;thus its practicality is enhanced. An adaptive fusion model using the fusion result as a supervisor to estimate the P-M and P-F is introduced. The fusion results are classified as 'reliable' and 'unreliable', Reliable results are used as a reference to update the weights in the fusion centre. Unreliable results are discarded. The convergence and error analysis of the system are demonstrated theoretically and by simulations. The paper concludes with simulation results that conform to the analysis.

关键词： distributed detection probability of false alarm reinforcement learning

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On the scalability of 2-D discrete wavelet transform algorithms

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MULTIDIMENSIONAL SYSTEMS AND signal processing 1997年第1-2期8卷 185-217页

作者： Fridman, J Manolakos, ES Communications and Digital Signal Processing (CDSP) Center for Research and Graduate Studies Electrical and Computer Engineering Department Northeastern University Boston

The ability of a parallel algorithm to make efficient use of increasing computational resources is known as its scalability. In this paper, we develop four parallel algorithms for the 2-dimensional Discrete Wavelet Transform algorithm (2-D DWT), and derive their scalability properties on Mesh and Hypercube interconnection networks. We consider two versions of the 2-D DWT algorithm, known as the Standard (S) and Non-standard (NS) forms, mapped onto P processors under two data partitioning schemes, namely checkerboard (CP) and stripped (SP) partitioning. The two checkerboard partitioned algorithms on the cut-through-routed (CT-routed) Mesh are scalable as M(2) = Omega(P log P) (Non-standard form, NS-CP), and as M(2) = Omega(P log(2) P) (Standard form, S-CP);while on the store-and-forward-routed (SF-routed) Mesh and Hypercube they are scalable as M(2) = Omega(P-3/3-gamma) (NS-CP), and as M(2) = Omega (P-2/2-gamma) (S-CP), respectively, where M(2) is the number of elements in the input matrix, and gamma is an element of (0, 1) is a parameter relating M to the number of desired octaves J as J = [gamma log M]. On the CT-routed Hypercube, scalability of the NS-form algorithms shows similar behavior as on the CT-routed Mesh. The Standard form algorithm with stripped partitioning (S-SP) is scalable on the CT-routed Hypercube as M(2) = Omega(P-2), and it is unscalable on the CT-routed Mesh. Although asymptotically the stripped partitioned algorithm S-SP on the CT-routed Hypercube would appear to be inferior to its checkerboard counterpart S-CP, detailed analysis based on the proportionality constants of the isoefficiency function shows that S-SP is actually more efficient than S-CP over a realistic range of machine and problem sizes. A milder form of this result holds on the CT- and SF-routed Mesh, where S-SP would, asymptotically, appear to be altogether unscalable.

关键词： wavelets scalability parallel processing

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Fast computation of the discrete Fourier transform of real data

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IEEE TRANSACTIONS ON signal processing 1997年第8期45卷 2010-2022页

作者： Sundararajan, D Ahmad, MO Swamy, MNS Department of Electrical and Computer Engineering Concordia University Montreal QUE Canada Centre for Signal Processing and Communications Department of Electrical and Computer Engineering Concordia University Montreal QUE Canada

Fast algorithms for the computation of the discrete Fourier transform (DFT) of real signals are important since the signals in practical situations are mostly real, The more efficient algorithms for real data are those that are derived from the algorithms for complex data. So far, all such algorithms use real array to store the data, However, as the data values are real and their transform values are mostly complex, two possible data structures can be used for these algorithms: real or complex, In this paper, DFT algorithms for real data that use a complex array for storing both the real data and their transform values are derived from the Cooley-Tukey radix-2 algorithm for complex data, This approach reduces the number of bit-reversal and array-index updating operations, eliminates independent data-swapping operations, and yields a computational structure that is almost as regular as that of the algorithms for complex data, Detailed derivations of the proposed algorithms for the computation of both the DFT of real data and the inverse DFT of the transform of real data, as well as their computational complexities, are presented, A C-language program of one of the proposed algorithms is given, illustrating the use of all the features of the new approach in software implementation, Comparison results are included to show that the proposed algorithms are faster and simpler than the real-valued split-radix and other algorithms.

关键词： Discrete Fourier transforms signal processing algorithms Algorithm design and analysis Fourier transforms Data structures Computational complexity Software algorithms Councils Arithmetic

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A new look at digital orthogonal transmultiplexers for CDMA communications

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IEEE TRANSACTIONS ON signal processing 1997年第1期45卷 263-267页

作者： Akansu, AN Tazebay, MV Haddad, RA Department of Electrical and Computer Engineering New Jersey Institute of Technology Center for Communications and Signal Processing Research University Heights Newark NJ USA

Orthogonal transmultiplexers have been successfully utilized for multiuser communications. They are of the FDMA type in their most common version. The transmultiplexers using frequency selective PR-QMF's as their user codes were reported in the literature. This approach conflicts with the requirements of a CDMA communications system. We introduce novel spread spectrum PR-QMF codes in this correspondence, wherein the orthogonality is distributed over both time and frequency domains. It is shown that the proposed multivalued spread spectrum PR-QMF codes with minimized auto and cross-correlation properties outperform the conventional binary Gold codes in CDMA communication scenarios considered in the correspondence.

关键词： .time and frequency filter bank PR-QMF PRQMF user codes multivalued spread spectrum binary Gold synthesis/analysis

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A novel algorithm to configure RBF networks

A novel algorithm to configure RBF networks

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1997 IEEE International Conference on Neural Networks (ICNN 97)

作者： Sohn, I Ansari, N Center for Communications and Signal Processing Research Department of Electrical and Computer Engineering University Heights Newark NJ 07102 United States Department of Electrical Engineering Southem Methodist University Dallas TX 75275 United States

ISBN: (纸本)0780341236

The most important factor in configuring an optimum radial basis function (RBF) network is the appropriate selection of the number of neural units in the hidden layer. This paper proposes a novel algorithm called the scattering based clustering (SBC) algorithm, in which the FSCL algorithm is first applied to let the neural units converge. Scatter matrices of the clustered data are then used to compute the sphericity for each k, where k is the number of clusters. The optimum number of neural units to be used in the hidden layer is then obtained. A comparative study is done between the SBC algorithm and RPCL algorithm, mid the result shows that the SBC algorithm outperforms other algorithms such as CL, FSCL, and RPCL.

关键词： Clustering algorithms

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Realization of 2-D linear-phase FIR filters based on the singular-value decomposition

Realization of 2-D linear-phase FIR filters based on the sin...

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Canadian Conference on electrical and computer engineering (CCECE)

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

In this paper, the singular-value decomposition (SVD) technique is investigated for the realization of 2-D linear-phase FIR filters with arbitrary magnitude responses. A parallel realization structure consisting of a number of 1-D FIR filters is obtained by applying the SVD to the impulse response of a 2-D filter. By using the symmetry property of the 2-D impulse response and by developing an appropriate unitary transform, a singular-value decomposition with symmetric and skew-symmetric singular vectors is obtained so that the constituent 1-D filters have linear-phase characteristics. It is shown that the number of parallel sections can be reduced significantly by neglecting the smaller singular values without introducing a large error in the magnitude response of the simplified 2-D filter.

关键词： Finite impulse response filter signal processing Two dimensional displays Digital filters Frequency response Electronic mail Image processing Convolution Matrix decomposition Symmetric matrices

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A closed-form solution for the design of complex FIR filters and its application to filter banks

A closed-form solution for the design of complex FIR filters...

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IEEE International Symposium on Circuits and Systems (ISCAS)

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

In this paper, the least-square design problem of complex FIR filters with arbitrary frequency response characteristics is investigated. A closed-form solution is obtained by solving the approximation problem analytically, enabling a very fast calculation of the impulse response of the filter to be designed. An application of the derived solution to QMF bank design is explored. By using the Butterworth approximation to obtain an IIR filter for the analysis part and by employing the closed-form solution to approximate a nonlinear-phase FIR filter for the synthesis part, a class of nearly perfect-reconstruction QMF bank is developed. It is shown that the mixed IIR/FIR filter bank not only has a very good reconstruction performance but also enjoys an extremely low design complexity.

关键词： Finite impulse response filter Closed-form solution Filter bank Channel bank filters Frequency response IIR filters Digital filters Application software signal processing Electronic mail

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New performance bounds for turbo codes

New performance bounds for turbo codes

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IEEE Conference and Exhibition on Global Telecommunications (GLOBECOM)

作者： T.M. Duman M. Salehi Communications and Digital Signal Processing Center Electrical and Computer Engineering Department Northeastern University Boston MA USA

We derive a new upper bound on the word and bit error probabilities of turbo codes with maximum likelihood decoding by using the Gallager bound instead of the standard union bound. Since the derivation of the bound for a given interleaver is intractable, we assume "uniform interleaving " as in the standard union bound applied to turbo codes. The result is a generalization of the transfer function bounds and remains useful for a wider range of signal to noise ratios, particularly for some range below the channel cut-off rate. Previously, for signal to noise ratios below the cut-off rate, the performance of turbo codes could only be predicted through simulation. We illustrate the usefulness of the new bound via some examples. We also discuss the possibility of extending the derived upper bound to some other codes.

关键词： Turbo codes Upper bound Error probability Maximum likelihood decoding Convolutional codes AWGN channels signal to noise ratio Concatenated codes Convolution Performance analysis

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Applications of space-time adaptive processing in wireless communications

Applications of space-time adaptive processing in wireless c...

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MILCOM, Military communications Conference

作者： P.M. Haimovich A. Shah Center for Communications and Signal Processing Department of Electrical and Computer Engineering New Jersey Institute of Technology Newark NJ USA

This paper studies the application of space-time adaptive processing (STAP) to increase the performance of wireless communications. STAP applied to CDMA systems is an efficient means to increase the capacity by providing diversity paths to combat multipath and by suppressing interference through spatial-temporal filtering. STAP may also be used to harden commercial systems for military applications by rejecting narrowband interferences in overlay situations. The main advantage of interference suppression in the spatial domain is its robustness with respect to the interference bandwidth. The performance of several STAP architectures is reviewed. The performance of wireless systems with array processing or STAP is degraded by errors in the estimation of the covariance matrix due to finite sample effects. Full and reduced-rank methods are analyzed with respect to their robustness to finite sample effects.

关键词： Interference suppression Robustness Wireless communication Multiaccess communication Filtering Narrowband Bandwidth Array signal processing Degradation Estimation error

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EM-ANN modelling and optimal chamfering of 90/spl deg/ CPW bends with air-bridges

EM-ANN modelling and optimal chamfering of 90/spl deg/ CPW b...

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Microwave, MTT-S International Symposium

作者： P.M. Watson K.C. Gupta Center for Communications and Signal Processing Research Department of Electrical and Computer Engineering New Jersey Institute of Technology University of Colorado Boulder Boulder USA Center for Communications and Signal Processing Research Department of Electrical and Computer Engineering New Jersey Institute of Technology University of Colorado Boulder USA

Electromagnetically-trained artificial neural network (EM-ANN) models for coplanar waveguide (CPW) 90/spl deg/ bends with air-bridges are presented. The optimal chamfer is determined for a conventional CPW bend where both the slot and strip are chamfered. Also, a novel compensated CPW bend is introduced where only the strip is chamfered. Optimum value of this chamfer is found to be the maximum chamfer allowed by air-bridge placement. This novel compensated CPW bend is shown to reduce the return loss from that in the conventional optimally chamfered CPW bend by 3 to 7 dB.

关键词： Coplanar waveguides Artificial neural networks Optical waveguides Electromagnetic waveguides Bridge circuits Electromagnetic modeling Strips MMICs Scattering parameters Insertion loss

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