Large buildings such as shopping malls, entertainment centers and hospitals can not be covered by outdoor base stations because of their large building area and large internal spacing. Signal coverage must be achieved by constructing MDAS indoor antenna distribution systems within buildings.

The MDAS multi-mode digital optical fiber distribution system is the first choice for building a large-scale Indoor distribution system. The MDAS system consists of three parts: the main unit MU, the expended unit EU, and the remote unit RU. The main MU coupled base station, RRU RF output, converts RF signals into digital optical signals and transmits them in four separate ways via fiber optics to four expended units, the EU.Each expended EU then transmits the digital optical signal in eight ways via fiber optics to eight remote- unit RUs.The remote unit RU processes digital signals into RF signals, amplifies them and outputs them to the antenna for coverage.

Taking a hotel indoor distribution system as an example.Coupling the RRU signal with an MDAS host, theMDAS host is then connected to two extensions unit EU, one of which is connected to four remote units in 4 ways and the other is connected to six remote units in six ways.Each remote terminal is connected to 6 omni antennas, each with a coverage radius of 10 meters.