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Sökning: swepub > (1990-1994) > Rapport > Viberg Mats

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1.
  • Andersson, Sören, et al. (författare)
  • A Study of Adaptive Arrays for Mobile Communication Systems
  • 1990
  • Rapport (övrigt vetenskapligt)abstract
    • The application of adaptive antenna techniques to increase the channel capacity in mobile radio communication is discussed. Directional sensitivity is obtained by using an antenna array at the base station, possibly both in receiving and transmitting mode. A scheme for separating several signals at the same frequency is proposed. The method is based on high-resolution direction finding following by optimal combination of the antenna outputs. Comparisons to a method based on reference signals are made. Computer simulations are carried out to test the applicability of the technique to scattering scenarios that typically arise in urban areas. The proposed scheme is found to have great potential in rejecting cochannel interference, albeit at the expense of high computational requirements.
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2.
  • Andersson, Sören, et al. (författare)
  • An Adaptive Array for Mobile Communication Systems
  • 1990
  • Rapport (övrigt vetenskapligt)abstract
    • The use of adaptive antenna techniques to increase the channel capacity is discussed. Directional sensitivity is obtained by using an antenna array at the base station, possibly both in receiving and transmitting mode. A scheme for separating several signals at the same frequency is proposed. The method is based on high-resolution direction-finding followed by optimal combination of the antenna outputs. Comparison with a method based on reference signals is made. Computer simulations are carried out to test the applicability of the technique to scattering scenarios that typically arise in urban areas. The proposed scheme is found to have great potential in rejecting cochannel interference, albeit at the expense of high computational requirements.
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5.
  • Ottersten, Björn, et al. (författare)
  • Analysis of Algorithms for Sensor Arrays with Invariance Structure
  • 1990
  • Rapport (övrigt vetenskapligt)abstract
    • The problem of estimating signal parameters from sensor array data is addressed. If the array is composed of two identical subarrays, (i.e. one invariance) the ESPRIT algorithm is known to yield parameter estimates in a very cost efficient manner. Recently, the total least squares (TLS) version of ESPRIT has been formulated in a subspace fitting framework. In this formulation, the ESPRIT concept is easily generalized to arrays exhibiting more than one invariance. The asymptotic properties for this class of algorithms are derived. The estimates are shown to be statistically efficient under certain assumptions. The case of a uniform linear array is studied in more detail, and a generalization of the ESPRIT algorithm is proposed by introducing row weighting of the subspace estimate.
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6.
  • Ottersten, Björn, et al. (författare)
  • Asymptotic Robustness of Sensor Array Processing Methods
  • 1990
  • Rapport (övrigt vetenskapligt)abstract
    • Methods for estimating the parameters of narrowband signals arriving at an array of sensors are analyzed. Asymptotic results for several estimators have recently appeared in the literature. With few exceptions, the previous analysis requires the incident signal waveforms to be Gaussian random variables. These results are shown to be valid under much more general conditions, i.e. the actual distribution of the signal waveforms does not affect the asymptotic properties of the parameter.
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7.
  • Ottersten, Björn, et al. (författare)
  • Exact and Large Sample ML Techniques for Parameter Estimation and Detection in Array Processing
  • 1991
  • Rapport (övrigt vetenskapligt)abstract
    • Sensor array signal processing deals with the problem of extracting information from a collection of measurements obtained from sensors distributed in space. The number of signals present is assumed to be finite, and each signal is parameterized by a finite number of parameters. Based on measurements of the array output, the objective is to estimate the signals and their parameters. This research area has attracted considerable interest for several years. A vast number of algorithms has appeared in the literature for estimating unknown signal parameters from the measured output of a sensor array.
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8.
  • Ottersten, Björn, et al. (författare)
  • Local Modeling and Robust Estimation for High-Resolution Direction Finding
  • 1991
  • Rapport (övrigt vetenskapligt)abstract
    • Many signal processing applications are concerned with estimating signal parameters with high accuracy from sensor array measurements. To obtain accurate location estimates, knowledge of the array response is required. Most estimation techniques are sensitive to perturbations in the array model and array calibration is often necessary. The authors discuss the issue of generating the array response parameterization from a finite number of noise-contaminated calibration vectors. An estimation technique based on local parametric modeling of the array response is proposed. The potential improvement using the suggested scheme rather than an ideal array model is demonstrated on real data collected from a full-scale hydroacoustic array. It is shown that, by applying the proposed technique together with a standard direction-of-arrival estimation procedure, a significant reduction in estimation bias can be obtained.
9.
  • Ottersten, Björn, et al. (författare)
  • Robust Source Localization Based on Local Array Response Modeling
  • 1992
  • Rapport (övrigt vetenskapligt)abstract
    • Many practical applications of signal processing require accurate determination of signal parameters from sensor array measurements. Most estimation techniques are sensitive to errors in the array response model. Thus, reliable array calibration schemes are of great importance. A paradigm for generating an array model from noise corrupted calibration vectors is developed. The key idea is to use a local parametric model of the sensor responses. The potential improvement using the suggested scheme is demonstrated on real data collected from a full-scale hydroacoustic array.
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10.
  • Stoica, Petre, et al. (författare)
  • An Instrumental Variable Approach to Array Processing in Spatially Correlated Noise Fields
  • 1992
  • Rapport (övrigt vetenskapligt)abstract
    • Signal parameter estimation from sensor array data is of great interest in a variety of applications, including radar, sonar, and radio communication. A large number of high-resolution (i.e., model-based) techniques have been suggested in the literature. The vast majority of these require knowledge of the spatial noise correlation matrix, which constitutes a significant drawback. A novel instrumental variable (IV) approach to the sensor array problem is proposed. By exploiting temporal correlatedness of the source signals, knowledge of the spatial noise covariance is not required. The asymptotic properties of the IV estimator are examined, and an optimal IV method is derived. Simulations are presented examining the properties of the IV estimators in data segments of realistic lengths.
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  • Resultat 1-10 av 24
  • [1]23Nästa
 
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