Additive white Gaussian noise (AWGN) is a channel model in which the only impairment to communication is a linear addition of wideband or white noise with a constant spectral density (expressed as watts per hertz of bandwidth) and a Gaussian distribution of amplitude. The model does not account for fading, frequency selectivity, interference, nonlinearity or dispersion. However, it produces simple and tractable mathematical models which are useful for gaining insight into the underlying behavior of a system before these other phenomena are considered.
Wideband Gaussian noise comes from many natural sources, such as the thermal vibrations of atoms in conductors (referred to as thermal noise or Johnson-Nyquist noise), shot noise, black body radiation from the earth and other warm objects, and from celestial sources such as the Sun.
The AWGN channel is a good model for many satellite and deep space communication links. It is not a good model for most terrestrial links because of multipath, terrain blocking, interference, etc. However, for terrestrial path modeling, AWGN is commonly used to simulate background noise of the channel under study, in addition to multipath, terrain blocking, interference, ground clutter and self interference that modern radio systems encounter in terrestrial operation.
Read more about Additive White Gaussian Noise: Channel Capacity, Effects in Time Domain, Effects in Phasor Domain
Famous quotes containing the words white and/or noise:
“We are all androgynous, not only because we are all born of a woman impregnated by the seed of a man but because each of us, helplessly and forever, contains the other—male in female, female in male, white in black and black in white. We are a part of each other. Many of my countrymen appear to find this fact exceedingly inconvenient and even unfair, and so, very often, do I. But none of us can do anything about it.”
—James Baldwin (1924–1987)
“It is as real
as splinters stuck in your ear. The noise we steal
is half a bell. And outside cars whisk by on the suburban street
and are there and are true.
What else is this, this intricate shape of air?
calling me, calling you.”
—Anne Sexton (1928–1974)