Large buildings such as shopping malls, entertainment centers and hospitals often cannot be fully covered by outdoor base stations because of their large size and complex internal layout. Reliable signal coverage therefore needs to be provided by constructing MDAS indoor antenna distribution systems inside the building.

The MDAS multi-mode digital optical fiber distribution system is an ideal solution for large-scale indoor coverage. An MDAS system typically consists of three components: a main unit (MU), expansion units (EUs) and remote units (RUs). The MU connects to the base station / RRU RF output, converts the RF signals into digital optical signals and distributes them over four fiber links to up to four EUs. Each EU then transmits the digital optical signal over eight fiber links to eight RUs. Each RU converts the digital signal back to RF, amplifies it and feeds the connected antennas to provide coverage.

Taking a hotel indoor distribution system as an example, the RRU signal is coupled to an MDAS host, which is connected to two EUs. One EU is connected to four remote units in four ways and the other is connected to six remote units in six ways. Each remote unit is connected to six omni antennas, each with a coverage radius of about 10 meters.