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66th IEEE Vehicular Technology Conference

作者： Gutierrez-Diaz-de-Leon, Carlos A. Cabrera-Bean, Margarita Patzold, Matthias Univ Politecn Cataluna Signal Theory & Commun Dept Campus Nord UPC D-5C Jordi Girona 1-3 Barcelona 08034 Spain Agder Univ Coll Fac Engn & Sci N-4876 Grimstad Norway

ISBN: (纸本)9781424402632

This paper reviews the pertinence and statistical behavior of symbol-spaced tapped-delay-line (TDL) models which are widely used to model wide-sense stationary uncorrelated scattering (WSSUS) channels. Symbol-spaced TDL models are obtained by sampling the channel impulse response (CIR) at a rate equal to the reciprocal of the symbol duration. They were proposed more than three decades ago within the context of band-limited systems and their applicability seems to be unquestionable. Nonetheless, we show here that these TDL models should be used with care to model WSSUS channels within such a context, because that would violate the channel's uncorrelated scattering (US) condition. We also show that symbol-spaced TDL models suffer from strong limitations in emulating the channel frequency correlation function (FCF). It is shown that this drawback leads to an inaccurate performance evaluation of wireless communication systems sensitive to the FCF. We discuss a simple solution to this problem by doubling the channel's sampling rate. The advantages of this solution will be demonstrated by some numerical examples.

关键词： frequency correlation function mobile radio channels multipath channels sampling theorem tapped-delay-line model WSSUS model

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Analysis and applications of backscattered frequency correlation function

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IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING 1999年第4期37卷 1895-1906页

作者： Sarabandi, K Nashashibi, A Univ Michigan Dept Elect Engn & Comp Sci Ann Arbor MI 48109 USA

In this paper, the application of the radar backscatter frequency correlation for classification and inversion of physical parameters of terrestrial targets is investigated. Traditionally, in radar remote sensing, the backscattering coefficients and the backscatter phase difference statistics of a distributed target are considered for estimating the biophysical parameters of interest. Because of the complex nature of random media scattering problems, however, target classification and parameter inversion algorithms are very convoluted. One obvious way of enhancing the success and accuracy of an inversion algorithm is to expand the dimension of the input vector space. Depending on the radar parameters, such as footprint (pixel) size, incidence angle, and the target attributes (physical parameters), the backscatter signal decorrelates as function of frequency. In this paper, analytical and experimental procedures are developed to establish a relationship between the complex frequency correlation function (FCF) of the backscatter and the radar and target attributes. Specifically, two classes of distributed targets are considered: 1) rough surfaces and 2) random media. Analytical expressions for the frequency correlation function are derived and it is shown that the effect of radar parameters can be expressed explicitly and thus removed from the measured correlation functions. The University of Michigan wideband polarimetric scatterometer systems are used to verify the theoretical models and inversion algorithms developed in this study.

关键词： frequency correlation function radar backscatter random media

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Performance of multicarrier DS/SSMA systems in frequency-selective fading channels

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2002年第2期1卷 236-244页

作者： Namgoong, J Lehnert, JS Purdue Univ Sch Elect & Comp Engn W Lafayette IN 47907 USA

Multicarrier direct-sequence spread-spectrum multiple-access systems in frequency-selective fading channels are investigated. A consistent channel model is used for each system. First, the tapped delay line (TDL) channel model with uniformly spaced, uncorrelated taps is investigated to model a complex Gaussian, wide-sense stationary, uncorrelated scattering channel. An approximate average bit-error-rate expression is obtained for the receiver with RAKE fingers on each subcarrier branch, whose outputs are combined according to the maximum signal-to-noise ratio criterion. Various system configurations are examined for the same TDL channel model, data rate, total system bandwidth, and excess bandwidth of the chip waveform. All the systems compared employ the same number of correlators. The numerical results show that, given a contiguous spectrum, the systems with more fractionally-spaced RAKE fingers per subchannel are more robust than the systems with more subcarriers.

关键词： frequency correlation function multicarrier multipath intensity profile spread-spectrum multiple-access tapped delay line

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Experimental studies on circular SAR imaging in clutter using angular correlation function technique

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IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING 1999年第5期37卷 2192-2197页

作者： Chan, TK Kuga, Y Ishimaru, A Univ Washington Dept Elect Engn Seattle WA 98195 USA

This paper describes a novel approach for three-dimensional (3-D) imaging in a heavy-clutter environment. The proposed approach consists of two techniques, The first calls for the use of a synthetic aperture radar (SAR) moving in a circular orbit, whereas the second involves using angular correlation function (ACF) measurement for achieving clutter suppression. To demonstrate the imaging and clutter suppression capabilities of this combined approach (circular-correlation SAR), microwave imaging experiments are conducted at X-band frequencies (7-13 GHz). It is found that in heavy-clutter environments, this combined SAR approach outperforms conventional SAR, resulting in clearer images with enhanced target-to-clutter ratio.

关键词： angular correlation function circular synthetic aperture radar clutter suppression confocal imaging correlation techniques frequency correlation function target detection 3-D image reconstruction

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Coherence bandwidth measurements in a suburban microcell at 62.4GHz

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ELECTRONICS LETTERS 1998年第4期34卷 329-330页

作者： Hammoudeh, A Sanchez, MG Univ Glamorgan Dept Elect & Informat Technol Pontypridd CF37 1DL M Glam Wales Univ Vigo Dept Tecnol Comun Vigo 36200 Spain

Results of experiments made at 62.4GHz to measure the coherence bandwidth in a suburban mobile radio environment are presented. The correlation coefficients between envelopes separated in frequency are measured and expressed as functions of distance from the base station. They are found to je highly variable with the location of the receiver in the microcell. I-rom these data, the frequency correlation function is computed and used to calculate the coherence bandwidth. Values of the coherence bandwidth for correlation levels of 0.5, 0.7 and 0.9 are given for 90% of the time.

关键词： 62.4 GHz EHF MM-wave link cellular radio coherence coherence bandwidth measurements correlation coefficients correlation theory frequency correlation function microwave links suburban microcell suburban mobile radio environment

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Coherence bandwidth measurements in an indoor microcell at 62.4GHz

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ELECTRONICS LETTERS 1998年第5期34卷 429-431页

作者： Hammoudeh, A Kermoal, JP Sanchez, MG Univ Glamorgan Dept Elect & Informat Technol Pontypridd CF37 1DL M Glam Wales Univ Vigo Dept Tecnoloxias Comunicac Vigo 36200 Spain

Results of experiments made at 62.4GHz in a long narrow corridor to measure the coherence bandwidth are presented. The correlation coefficients between envelopes separated in frequency are measured and expressed as functions of distance between terminals. They are found to be highly variable with the location of the terminals in the microcell. From these data the frequency correlation function is computed and used to calculate the coherence bandwidth. The coherence bandwidths for correlation levels of 0.5, 0.7 and 0.9 are given for 90% of the time.

关键词： Mobile radio systems frequency correlation function 62.4 GHz correlation methods coherence indoor microcell cellular radio MM-wave mobile radio coherence bandwidth measurement corridor indoor radio

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ON THE THEORY OF DELTA-K RADAR OBSERVATIONS OF OCEAN SURFACE-WAVES

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IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION 1995年第8期43卷 843-850页

作者： TATARSKII, VI CLIFFORD, SF Department of COMMNOAA Boulder CO USA

We consider the theory of waves scattered from a moving, rough, and dispersive surface in the small perturbation limit, The first-order scattered field for a time-dependent surface is obtained in the far zone of scattering in terms of the two-dimensional spectral amplitude of the surface and its dispersion relation, We develop a rigorous Delta k radar theory and show that the nonzero output of a Delta k radar occurs only when the Bragg condition for each signal component is satisfied separately, The frequency correlation function of the scattered field is then proportional to the mean value of the product of the spectral amplitudes of the surface at the corresponding Bragg wavenumbers. The mean value of this product is nonzero only for surfaces that have a locally varying spectrum and is proportional to the Fourier transform (with the argument Delta k) of the variation of the local spectrum with respect to the pattern position, Such variations may be caused by either amplitude or phase modulation of the surface structure, In the former case, our results are similar to the results of existing theory. The latter case of phase modulation of the surface (for example, internal waves interacting with capillary waves) cannot be explained by previous theory.

关键词： Fourier transforms amplitude modulation electromagnetic wave scattering ocean waves phase modulation radar theory remote sensing by radar Bragg condition Fourier transform capillary waves dispersion relation dispersive surface first- frequency correlation function phase modulation ocean waves Electromagnetic wave scattering scattered field Radar remote sensing mean value dispersion relations amplitude modulation Surfaces Radar theory Fourier Transform capillary waves ocean surface

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STATISTICAL AR MODELS FOR THE frequency SELECTIVE INDOOR RADIO CHANNEL

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ELECTRONICS LETTERS 1990年第15期26卷 1133-1135页

作者： PAHLAVAN, K HOWARD, SJ RAYTHEON CO MARLBOROUGHMA 01752

A statistical model of the indoor radio channel is proposed that is derived from a second order autoregressive process representation of the channel frequency response. The accuracy of the statistical model is examined by comparing the cumulative distribution functions of the RMS delay spread and the 3 dB width of the frequency correlation function computed from the regenerated data with that of the measurements performed in two indoor radio propagation studies in the 0.9-1.1 GHz band.

关键词： 0.9 to 1.1 GHz 3 dB width RMS delay spread channel frequency response cumulative distribution functions fading frequency correlation function frequency selective indoor radio channel indoor radio propagation studies microwave links radiowave propagation regenerated data second order autoregressive process statistical model

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frequency-DOMAIN MEASUREMENTS OF INDOOR RADIO CHANNELS

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ELECTRONICS LETTERS 1989年第24期25卷 1645-1647页

作者： PAHLAVAN, K HOWARD, SJ RAYTHEON CO MARLBOROUGHMA 01752

frequency responses of the indoor radio channel for 128 locations in an office and a research laboratory are analysed. Some statistics on the number of fades are determined. The cumulative distribution function (CDF) of the 3 dB bandwidth of the frequency correlation function is presented, and experimental results relating the RMS delay spread of the channel and the inverse of the 3 dB width of the frequency correlation function are given.

关键词： 3 dB bandwidth CDF RMS delay spread cumulative distribution function fading fading statistics frequency correlation function frequency response frequency response indoor radio channels office radiocommunication radiowave propagation research laboratory telecommunication channels

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