What is a Distributed Antenna System (DAS)?
The DAS Forum defines DAS as “A network of spatially separated antenna nodes connected to a common source via transport medium that provides wireless service within a geographic area or structure,” but what does this mean, and how does it all work?
Typically, the objective of DAS network implementation is to capture wireless radio frequency (RF) signals, and to make them available where reception would be difficult, if not impossible, because of environmental variables. For example: A building’s basement, because they are below grade, are typically places with poor to nonexistent signal, but with a properly implemented DAS network, maintaining wireless connectivity becomes a possibility.
For nearly the past twenty years, DAS networks have become common telecommunications networks in office buildings, malls, arenas, stadiums, manufacturing facilities, power plants, airports and a multitude of other sites. All of these structures present challenges for the reception of wireless signals because of their building materials, and possibly because of their location, but with the help of an active in-building DAS network, these challenges can be overcome. Beyond coverage issues, when connected to a radio source like a base station or small cell, a DAS can be used to extend coverage and capacity within a venue.
Staying connected is vital, and DAS networks make staying connected possible in places where doing so may be difficult, if not impossible. The end results of a properly implemented DAS network are keeping people in touch with important people in their lives, keeping them in touch with vital information, along with providing greater safety, convenience and productivity.
In the illustration above, we see the basic building blocks of a traditional in-building DAS solution. RF signals are fed into the head end of the DAS network (normally located in the building’s master communications closet (MC)) by either a radio repeater connected to a donor antenna on the roof of the building or a base station provided by the respective wireless operator. At the head end, the RF signals are filtered, amplified, and converted to light. Once converted to light, the signals are transmitted to remote units located throughout the building’s telecom closets (TC) over fiber optic cable. The remote units then convert the optical signal back to RF, which is distributed throughout the building via coaxial cable to multiple ceiling mounted low profile serving antennas.