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International Conference on Acoustics, Speech, and signal processing (ICASSP)

作者： F. Sattar G. Salomonsson Signal Processing Group Department of Electrical Engineering and Computer Science Lunds University Lund Sweden

A non-parametric estimation method based on a series expansion of a signal by a set of basis functions is presented. The method is used to estimate the waveform of event-related signals which have a transient behaviour with unknown shapes and time delays which vary randomly after a known event time. The quality of the estimate depends on the choice of the set of basis functions. Two different sets of basis functions are designed from a template, which contains a priori information, by using one uniform and one non-uniform bandpass filter bank, respectively. Each of the two sets is enlarged by a number of delayed copies of each basis function by employing FIR-filters, the coefficients of which are determined in terms of squared error. The method is evaluated and compared with the Karhunen-Loeve expansion.< >

关键词： Channel bank filters Filter bank signal processing Shape computer science Delay estimation Delay effects Band pass filters Additive noise signal generators

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Performance of a frequency hop spread spectrum multiple access radio network in a factory environment

Performance of a frequency hop spread spectrum multiple acce...

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IEEE Southeastcon

作者： A. Orichi D.B. Koch Communications Information and Signal Processing Group Department of Electrical and Computer Engineering University of Tennessee Knoxville TN USA

Wireless indoor networks which can provide terminal portability to any node in the network, promise to reduce significantly the expense and troubles of wiring and rewiring associated with wired networks. Since wireless systems operate on bandlimited channels and have to adjust to the constant fluctuations of the indoor environment (i.e., multipath and intermittent fading), any viable wireless technology should be able to accommodate those constraints. A very attractive wireless technology for indoor networks is spread spectrum because of its ability to mitigate multipath fading and incorporate multiple access for bandwidth efficient sharing. A simulated model for a noncoherent FH/BFSK spread spectrum multiple access indoor network in a factory environment is developed. The system is evaluated based on the bit error rate (BER) performance for various chip rates, data rates, and number of hopping frequencies for a given signal to noise plus interference density ratio and the results are compared to theoretical upper and lower bounds.< >

关键词： Frequency Spread spectrum communication Fading Bit error rate Wiring Fluctuations Indoor environments Bandwidth Production facilities Working environment noise

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ERROR PERFORMANCE OF SYNCHRONOUS MULTIUSER CODE-DIVISION MULTIPLE-ACCESS DETECTOR WITH MULTIDIMENSIONAL ADAPTIVE CANCELER

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EUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS 1994年第6期5卷 719-724页

作者： SIVESKI, Z BARNESS, Y CHEN, DW Center for Communications and Signal Processing Electrical and Computer Engineering Department New Jersey Institute of Technology University Heights Newark NJ 07102 - USA Was on sabbatical with Delft University of Technology Faculty of Electrical Engineering Telecommunications and Traffic-Control Systems Group Delft - The Netherlands.

A code division multiple access detector that employs a combination of a decorrelator and a multidimensional interference canceler is considered. The weights of the canceler are adaptively controlled using a steepest descent algorithm. The probability of error is evaluated and compared to those of the decorrelating detector and a similar, fixed-weights scheme that requires an estimation of received signal energies. It is shown that the proposed two-stage detector provides substantial improvement over the decorrelating detector, particularly in the presence of strong interfering signals. This is especially noticeable in the high bandwidth efficiency cases. It is also observed that in the presence of weak interferers, the proposed scheme performs better than its fixed-weights counterpart.

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Bootstrapped decorrelating algorithm for adaptive interference cancelation in synchronous CDMA communications systems

Bootstrapped decorrelating algorithm for adaptive interferen...

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IEEE International Symposium on Spread Spectrum Techniques and Applications

作者： Y. Bar-Ness Z. Siveski D.W. Chen Faculty of Electrical Engineering Telecommunications and Traffic-Control Systems Group Delft University of Technnology Delft Netherlands Center for Communications and Signal Processing Electrical and Computer Engineering Department New Jersey Institute of Technology Newark NJ USA

A code division multiple access detector that employs a combination of a correlation detector and a multiuser adaptive interference canceler was previously proposed by the authors. The weights of the canceler are adaptively controlled by the steepest descent algorithm using the minimum power criterion of the canceler outputs. It was shown that such a canceler substantially outperforms the decorrelating detector and has almost the same error probability as a canceler that uses reliable estimates of the received signal energies. In this paper, a different weight control criterion based on minimizing the correlation between the signals at the outputs of the canceler is used, and its performance is compared to that obtained with the minimum power criterion. It is shown that both cancelers have almost the same performance, particularly when SNR is modestly high. Although it is not shown in this paper, we believe that minimizing correlation rather than power outputs is a more suitable criterion when dealing with highly dispersive channels.< >

关键词： Decorrelation Interference cancellation Code division multiplexing Multiaccess communication Detectors signal processing algorithms Filters Impedance matching Communication system traffic Telecommunication traffic

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Error performance of the blind decision feedback equalizer using decorrelation

Error performance of the blind decision feedback equalizer u...

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MILCOM, Military Communications Conference

作者： R.E. Kamel Y. Bar-Ness Center for Communications and Signal Processing Department of Electrical and Computer Engineering New Jersey Institute of Technology Newark NJ USA Telecommunications & Traffic-Control Systems Group Delft University of Technnology Delft Netherlands

The decision feedback equalizer has the advantage of compensating for channel amplitude distortion without enhancing noise. Conventional decision feedback equalizers require a training sequence to help them adapt to unknown channel characteristics. Training sequences are not always appropriate. In such situations blind equalizers are more suitable. The blind decision feedback equalizer inherits from the conventional the advantage of not enhancing noise, while compensating for severe ISI. It is thus superior over the blind linear equalizer. On the other hand the blind decision feedback equalizer also suffers from error propagation. In this paper we study the transient behavior of the blind DFE. This is done by deriving an upper bound on the probability of error due to residual ISI and show that it vanishes for the noiseless case. We also determine lower and upper bounds on the probability of error for the additive white Gaussian noise case. The upper bound obtained is the same as that of Duttweiler, et al. (1974). Using a different approach from that of Duttweiler, et al., we derive a lower bound. This bound is tighter than tile "no ISI" lower bound.< >

关键词： Decision feedback equalizers Decorrelation Upper bound Blind equalizers Intersymbol interference Additive white noise Steady-state Convergence Gaussian noise AWGN

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ONE-BIT SPECTRAL-CORRELATION ALGORITHMS

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IEEE TRANSACTIONS ON signal processing 1993年第1期41卷 423-427页

作者： GARDNER, WA ROBERTS, RS Signal Processing Group Department of Electrical and Computer Engineering University of California Davis CA USA Los Alamos National Laboratory Los Alamos NM USA Signal Processing Group. Department of Electrical and Computer Engineering University of California Davis CA USA

A technique that greatly simplifies the computational complexity of digital cyclic spectral analysis algorithms is presented. The technique, which is based on Bussgang's theorem, replaces complex multiplications in spectral correlation operations with simple sign-change and data-multiplexing operations. Moreover, the technique is applicable to both time- and frequency-averaging algorithms. A simulation study that compares the computed results obtained using the new technique with results from standard time- and frequency-averaging algorithms shows that the new technique is very promising, particularly for frequency-averaging algorithms.

关键词： signal processing algorithms Frequency estimation Spectral analysis signal analysis Instruments signal processing Bandwidth Aging Phase measurement Laboratories

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Performance of a direct sequence code division multiple access cellular network

Performance of a direct sequence code division multiple acce...

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IEEE Southeastcon

作者： M.W. Twiggs D.B. Koch Communications Infod Signal Proc Department of Electrical and Computer Engineering University of Tennessee Knoxville TN USA Communications Information and Signal Processing (CISP) Group Department of Electrical and Computer Engineering University of Tennessee Knoxville TN USA

A DS/CDMA (direct-sequence code division multiple access) system using BPSK (binary phase shift keying) modulation is simulated to determine the bit error probabilities for various numbers of users with a processing gain close to that of a cellular network. The results are compared to results obtained using the Gaussian approximation equations. The results obtained are to the feasibility of a DS/CDMA cellular network. It is concluded that DS/CDMA cellular networks appear to offer higher subscriber capacities than existing analog or TDMA (time division multiple access) formats. In addition, DS/CDMA offers additional advantages such as inherent privacy through the use of spreading codes and the ability to combat problems such as multipath fading and narrowband noise.< >

关键词： Direct-sequence code-division multiple access Multiaccess communication Land mobile radio cellular systems Binary phase shift keying Time division multiple access Phase modulation Modulation coding Error probability Gaussian approximation Equations

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Multichannel spectral analysis for tube leak detection

Multichannel spectral analysis for tube leak detection

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IEEE Southeastcon

作者： Q. Wan D.B. Koch K. Morris Communications Information and Signal Processing Group Electrical and Computer Engineering DepartmentCommunications Information Signal Processing Group University of Tennessee Knoxville Knoxville TN USA Tennessee Valley Authority Chattanooga TN USA

Research to develop multichannel spectral analysis methods, including classical and parametric techniques, for tube leak detection in fossil-fueled power plant boilers is described. Acoustic analysis is employed to detect leaks. The main idea is to monitor the continuous noise environment of the furnace and to look for specific acoustic signatures produced by leaks. A signal spectrum is estimated using the LabVIEW software package. The coherence spectrum of 2-channel signals estimated by the autoregressive technique is shown.< >

关键词： Spectral analysis Leak detection Power generation Boilers Acoustic signal detection Monitoring Acoustic noise Working environment noise Furnaces Software packages

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A DIGITAL signal-processing ARCHITECTURE FOR ITERATIVE DECONVOLUTION RESTORATION ALGORITHMS

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IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT 1992年第1期41卷 147-151页

作者： WHITTED, RB CRILLY, PB Communications Information and Signal Processing (CISP) Group Department of Electrical and Computer Engineering University of Tennessee Knoxville Knoxville TN USA

This paper will present a VLSI DSP chip that will significantly improve the processing throughout for a general class of iterative deconvolution algorithms. The design will be based on a systolic array concept. This will enable these algorithms to be used for real-time DSP applications which formerly, due to speed limitations, were not possible. The increased class of applications will enable further understanding of these applications. The higher throughout will also enable the researcher to further take advantage of the features unique to iterative deconvolution.

关键词： .Digital signal processing systolic chromatographic Iterative Deconvolution

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Enhancement of ultrasound images by multiscale analysis

Enhancement of ultrasound images by multiscale analysis

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IEEE-SP International Symposium on Time-Frequency and Time-Scale Analysis

作者： F. Bietrix B. Lovstrom G. Salomonsson Signal Processing Group Department of Electrical Engineering and Computer Science University of Lund Lund Sweden

A multiscale nonlinear image processing method for reducing noise is presented. The input image is decomposed into several images of larger scale. Edge detection in these large-scale images is performed, and the result is used in the reconstruction of an image of the original scale. The method is described in general, and a specific example is given in which speckle reduction of an ultrasound image is performed.< >

关键词： Ultrasonic imaging Image analysis Speckle signal resolution signal processing Image reconstruction Image resolution Biological materials Biomedical imaging Acoustic scattering

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