Distributed antenna system
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A distributed antenna system is a network of spatially separated antenna nodes connected to a common source via a transport medium that provides wireless service within a geographic area or structure.
A typical DAS node for the Videotron 3G network in Montreal, Quebec
DAS deployed by Transit Wireless in New York City Subway to provide WiFi, cellular voice and data coverage. The RF node with three antennas was at the platform and another antenna near the stairs on the far side.
A Verizon DAS deployed at a Shell gas station (Cockeysville, MD)
Fading
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In wireless communications, fading is the variation of signal attenuation over variables like time, geographical position, and radio frequency. Fading is often modeled as a random process. In wireless
Distributed antenna system
…less power is wasted in overcoming penetration and shadowing losses, and because a line-of-sight channel is present more frequently, leading to reduced fade depths and reduced delay spread. By distributing antennas throughout a facility, DAS installations reduce the need for high-powered transmitters and help…
Frequency-selective time-varying fading causes a cloudy pattern to appear on a spectrogram. Time is shown on the horizontal axis, frequency on the vertical axis and signal strength as grey-scale intensity.