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Radio Frequency Propagation Fading Books LLC

Radio Frequency Propagation Fading

Books LLC

Published May 25th 2010
ISBN : 9781156863015
Paperback
44 pages
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 About the Book 

Chapters: Rayleigh Fading, Fade Margin, Fading Distribution, Automatic Sounding, Rain Fade, Weibull Fading, Selective Fading, Rician Fading, Thermal Fade, Backhoe Fade. Source: Wikipedia. Pages: 43. Not illustrated. Free updates online. PurchaseMoreChapters: Rayleigh Fading, Fade Margin, Fading Distribution, Automatic Sounding, Rain Fade, Weibull Fading, Selective Fading, Rician Fading, Thermal Fade, Backhoe Fade. Source: Wikipedia. Pages: 43. Not illustrated. Free updates online. Purchase includes a free trial membership in the publishers book club where you can select from more than a million books without charge. Excerpt: Rayleigh fading is a statistical model for the effect of a propagation environment on a radio signal, such as that used by wireless devices. Rayleigh fading models assume that the magnitude of a signal that has passed through such a transmission medium (also called a communications channel) will vary randomly, or fade, according to a Rayleigh distribution the radial component of the sum of two uncorrelated Gaussian random variables. Rayleigh fading is viewed as a reasonable model for tropospheric and ionospheric signal propagation as well as the effect of heavily built-up urban environments on radio signals. Rayleigh fading is most applicable when there is no dominant propagation along a line of sight between the transmitter and receiver. If there is a dominant line of sight, Rician fading may be more applicable. Rayleigh fading is a reasonable model when there are many objects in the environment that scatter the radio signal before it arrives at the receiver. The central limit theorem holds that, if there is sufficiently much scatter, the channel impulse response will be well-modelled as a Gaussian process irrespective of the distribution of the individual components. If there is no dominant component to the scatter, then such a process will have zero mean and phase evenly distributed between 0 and 2 radians. The envelope of the channel response will therefore be Rayleigh distributed. Calling this random variable, it will have a probability density function: where . Often, the gain and phase elements of a channels distortion are conveniently rep...More: http: //booksllc.net/?id=81173