What is meant by Rayleigh fading?
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 is most applicable when there is no dominant propagation along a line of sight between the transmitter and receiver.
What is Rayleigh multipath fading?
Rayleigh fading is a model that can be used to describe the form of fading that occurs when multipath propagation exists. In any terrestrial environment a radio signal will travel via a number of different paths from the transmitter to the receiver. These objects may serve to reflect, refract, etc the signal.
What is fast fading and slow fading?
Slow fading can be caused by events such as shadowing, where a large obstruction such as a hill or large building obscures the main signal path between the transmitter and the receiver. Fast fading occurs when the coherence time of the channel is small relative to the delay requirement of the application.
How do you overcome Rayleigh fading?
To overcome the effects of Rayleigh fading in a mobile environment, sequential tone signalling may be used (DTI, 1981b). Here a unique single tone corresponding to each digit is sequentially transmitted, together with a unique ‘repeat’ tone in place of the digit tone in the case of repeated digits.
What is fast fading channel?
In other works, fast fading occurs when the coherence time of the channel TD is smaller than the symbol period of the transmitted signal T such as TD< . This causes frequency dispersion or time selective fading due to Doppler spreading [3],[4].
What is the difference between the Rayleigh and Rician fading channels?
Rayleigh fading model assumes that the magnitude of a signal that has passed through transmission medium will vary randomly, or fade, according to a Rayleigh distribution. Rician model considers that the dominant wave can be a phasor sum of two or more dominant signals, e.g. the line-of-sight, plus a ground reflection.
What is the major cause of fading?
Ultraviolet rays are one of the causes of fading because they can break down chemical bonds and fade the color in an object. Other major contributors to fading include visible light and solar heat. Other objects may reflect the light more, which makes them less prone to fade. Sunlight causes some foods to fade.
Why small scale fading is called Rayleigh fading?
Small-scale fading is also called Rayleigh fading because when the number of versions of the transmitted signal which arrive at slightly different times is large, the envelope of the received signal is statistically described by a Rayleigh distribution if there is no line-of-sight component.
What is the difference between flat and selective fading?
“Flat fading, or nonselective fading, is that type of fading in which all frequency components of the received signal fluctuate in the same proportions simultaneously. Selective fading affects unequally the different spectral components of a radio signal.”
What’s the difference between a Rayleigh fading and a Rician fading?
Both Rayleigh and Rician fading refer to fast fading in wireless communication channels. When all of the multipath signals have random uniformly distributed phase, then the amplitude of the resulting signal has a Rayleigh distribution and the fading is called Rayleigh fading.
How is the fast Walsh transform used in Rayleigh fading?
The fast Walsh transform can be used to efficiently generate samples using this model. The Jakes’s model also popularised the Doppler spectrum associated with Rayleigh fading, and, as a result, this Doppler spectrum is often termed Jakes’s spectrum.
How does Doppler shift affect Rayleigh fading channel?
How rapidly the channel fades will be affected by how fast the receiver and/or transmitter are moving. Motion causes Doppler shift in the received signal components. The figures show the power variation over 1 second of a constant signal after passing through a single-path Rayleigh fading channel with a maximum Doppler shift of 10 Hz and 100 Hz.
What is the PEP of a Rayleigh fast fading channel?
In i.i.d. Rayleigh fast fading channels, it is shown in Appendix D that the average PEP may be expressed as where η = ρ / (4sin2β). Because the integral over β is usually not straightforward, an upper bound of (6.7) is based on the Chernoff bound Q(x) ⩽ e – x2 / 2 (see Appendix D),