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Journal ArticleDOI

A statistical theory of mobile-radio reception

08 Jul 1968-Bell System Technical Journal (John Wiley & Sons, Ltd)-Vol. 47, Iss: 6, pp 957-1000
TL;DR: In this article, the statistical characteristics of the fields and signals in the reception of radio frequencies by a moving vehicle are deduced from a scattering propagation model, assuming that the field incident on the receiver antenna is composed of randomly phased azimuthal plane waves of arbitrary angle angles.
Abstract: The statistical characteristics of the fields and signals in the reception of radio frequencies by a moving vehicle are deduced from a scattering propagation model. The model assumes that the field incident on the receiver antenna is composed of randomly phased azimuthal plane waves of arbitrary azimuth angles. Amplitude and phase distributions and spatial correlations of fields and signals are deduced, and a simple direct relationship is established between the signal amplitude spectrum and the product of the incident plane waves' angular distribution and the azimuthal antenna gain. The coherence of two mobile-radio signals of different frequencies is shown to depend on the statistical distribution of the relative time delays in the arrival of the component waves, and the coherent bandwidth is shown to be the inverse of the spread in time delays. Wherever possible theoretical predictions are compared with the experimental results. There is sufficient agreement to indicate the validity of the approach. Agreement improves if allowance is made for the nonstationary character of mobile-radio signals.
Citations
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Book
01 Jan 2005

9,038 citations

Journal ArticleDOI
David J. Thomson1
01 Sep 1982
TL;DR: In this article, a local eigenexpansion is proposed to estimate the spectrum of a stationary time series from a finite sample of the process, which is equivalent to using the weishted average of a series of direct-spectrum estimates based on orthogonal data windows to treat both bias and smoothing problems.
Abstract: In the choice of an estimator for the spectrum of a stationary time series from a finite sample of the process, the problems of bias control and consistency, or "smoothing," are dominant. In this paper we present a new method based on a "local" eigenexpansion to estimate the spectrum in terms of the solution of an integral equation. Computationally this method is equivalent to using the weishted average of a series of direct-spectrum estimates based on orthogonal data windows (discrete prolate spheroidal sequences) to treat both the bias and smoothing problems. Some of the attractive features of this estimate are: there are no arbitrary windows; it is a small sample theory; it is consistent; it provides an analysis-of-variance test for line components; and it has high resolution. We also show relations of this estimate to maximum-likelihood estimates, show that the estimation capacity of the estimate is high, and show applications to coherence and polyspectrum estimates.

3,921 citations

01 Jan 1993
TL;DR: The principles of radio propagation in indoor environments are reviewed, the channel is modeled as a linear time-varying filter at each location in the three-dimensional space, and the properties of the filter's impulse response are described.

1,735 citations

Journal ArticleDOI
01 Jul 1993
TL;DR: In this paper, a tutorial survey of radio propagation in indoor environments is presented, where the channel is modeled as a linear time-varying filter at each location in the 3D space, and the properties of the filter's impulse response are described.
Abstract: In this tutorial survey the principles of radio propagation in indoor environments are reviewed. The channel is modeled as a linear time-varying filter at each location in the three-dimensional space, and the properties of the filter's impulse response are described. Theoretical distributions of the sequences of arrival times, amplitudes and phases are presented. Other relevant concepts such as spatial and temporal variations of the channel, large-scale path losses, mean excess delay and RMS delay spread are explored. Propagation characteristics of the indoor and outdoor channels are compared and their major differences are outlined. Previous measurement and modeling efforts are surveyed, and areas for future research are suggested. >

1,696 citations

Journal ArticleDOI
TL;DR: The mutual resistance condition offers a powerful design tool, and examples of new mobile diversity antennas are discussed along with some existing designs.
Abstract: The conditions for antenna diversity action are investigated. In terms of the fields, a condition is shown to be that the incident field and the far field of the diversity antenna should obey (or nearly obey) an orthogonality relationship. The role of mutual coupling is central, and it is different from that in a conventional array antenna. In terms of antenna parameters, a sufficient condition for diversity action for a certain class of high gain antennas at the mobile, which approximates most practical mobile antennas, is shown to be zero (or low) mutual resistance between elements. This is not the case at the base station, where the condition is necessary only. The mutual resistance condition offers a powerful design tool, and examples of new mobile diversity antennas are discussed along with some existing designs.

1,423 citations

References
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Journal ArticleDOI
M. B. Wilk1, R. Gnanadesikan1
TL;DR: This paper describes and discusses graphical techniques, based on the primitive empirical cumulative distribution function and on quantile (Q-Q) plots, percent (P-P) plots and hybrids of these, which are useful in assessing a one-dimensional sample, either from original data or resulting from analysis.
Abstract: SUMMARY This paper describes and discusses graphical techniques, based on the primitive empirical cumulative distribution function and on quantile (Q-Q) plots, percent (P-P) plots and hybrids of these, which are useful in assessing a one-dimensional sample, either from original data or resulting from analysis. Areas of application include: the comparison of samples; the comparison of distributions; the presentation of results on sensitivities of statistical methods; the analysis of collections of contrasts and of collections of sample variances; the assessment of multivariate contrasts;_ and the structuring of analysis of variance mean squares. Many of the objectives and techniques are illustrated by examples. This paper reviews a variety of old and new statistical techniques based on the cumulative distribution function and its ramifications. Included in the coverage are applications, for various situations and purposes, of quantile probability plots (Q-Q plots), percentage probability plots (P-P plots) and extensions and hybrids of these. The general viewpoint is that of analysis of data by statistical methods that are suggestive and constructive rather than formal procedures to be applied in the light of a tightly specified mathematical model. The technological background is taken to be current capacities in data collection and highspeed computing systems, including graphical display facilities. It is very often useful in statistical data analysis to examine and to present a body of data as though it may have originated as a one-dimensional sample, i.e. data which one wishes to treat for purposes of analysis, as an unstructured array. Sometimes this is applicable to ' original' data; even more often such a viewpoint is useful with 'derived' data, e.g. residuals from a model fitted to the data. The empirical cumulative distribution function and probability plotting methods have a key role in the statistical treatment of one-dimensional samples, being of relevance for summarization and palatable description as well as for exposure and inference.

1,301 citations

Journal ArticleDOI
TL;DR: A number of statistical properties of such a current which consists of a sinusoidal component plus a random noise component are given here.
Abstract: In Some technical problems we are concerned with a current which consists of a sinusoidal component plus a random noise component. A number of statistical properties of such a current are given here. The present paper may be regarded as an extension of Section 3.10 of an earlier paper,1 “Mathematical Analysis of Random Noise”, where some of the simpler properties of a sine wave plus random noise are discussed.

874 citations

Journal ArticleDOI
TL;DR: In this paper, a comparison of the transmission performance of 150, 450, 900, and 3700 cm in a mobile radiotelephone type of service is made. But, the results show that while transmission above roughly 1000 cm for these services is not impossible, it would be decidedly more difficult to employ these frequencies satisfactorily.
Abstract: Based on a series of experiments, a comparison is made of the transmission performance of 150, 450, 900, and 3700 mc in a mobile radiotelephone type of service. This comparison indicates that 450 mc is superior transmission-wise to the presently used 150-mc band in urban and suburban areas. In fact a broad optimum in performance falls in the neighborhood of 500 mc It is concluded that this range of frequencies would be well suited for providing coverage to meet the large scale needs which are anticipated in and around metropolitan areas. Although higher frequencies are less desirable, the tests indicate that 900 mc is somewhat to be favored over 150 mc from a transmission standpoint if full use is made of the possible antenna gain. Above this frequency, transmission performance falls off even assuming the maximum practical antenna gain. Transmission at 3700 mc suffers an additional impairment in that the fluctuations in received carrier level occur at an audible rate as the mobile unit moves at normal speeds. It is concluded that while transmission above roughly 1000 mc for these services is not impossible, it would be decidedly more difficult to employ these frequencies satisfactorily.

85 citations

Journal ArticleDOI
TL;DR: In this paper, the authors derived statistical properties for mathematical models of the multipath fading encountered in mobile radio and compared some receiving systems which use several antennas to combat fading, including a system of J. R. Pierce which has electric and magnetic dipole antennas and computes the electromagnetic energy density at a point.
Abstract: Statistical properties are derived for mathematical models of the multipath fading encountered in mobile radio. These properties are used to compare some receiving systems which use several antennas to combat fading. Particular attention is given to a system of J. R. Pierce which has electric and magnetic dipole antennas and computes the electromagnetic energy density at a point. The statistical properties considered here include energy density distribution functions, correlation coefficients, and the power spectrum of the energy density observed at a moving point.

71 citations