Additive White Gaussian Noise

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:

    It was common practice for me to take my children with me whenever I went shopping, out for a walk in a white neighborhood, or just felt like going about in a white world. The reason was simple enough: if a black man is alone or with other black men, he is a threat to whites. But if he is with children, then he is harmless, adorable.
    Gerald Early (20th century)

    I’ve almost gained my heav’nly home; My spirit loudly sings;
    The holy ones behold they come, I hear the noise of wings.
    O come, angel band, Come and around me stand.
    O bear me away on your snowy wings, To my immortal home.
    T. Haskell, minister and hymn-writer. Published in Christian Harmony. “Angel Band,” l. 5-8.