Chapter 4
Distributed Antenna Systems
The lesson learned from Section 3.5 is clear; you need to distribute a uniform dominant signal inside the building, from the indoor cell, using indoor antennas in order to provide sufficient coverage and dominance. In order to do so you must split the signal from the indoor base station to several antennas throughout the inside of the building.
Ideally these antenna points should operate roughly at the same power level, and have the same loss/noise figure on the uplink to the serving base station. The motivation for the uniformly distributed coverage level for all antennas in the building is the fact that all the antennas will operate on the same cell, controlled by the same parameter setting. In practice passive DAS will often not provide a uniform design to all antennas; you might have one antenna with 10 dB loss from the base station, and in the same cell an antenna with 45 dB loss back to the base station, and the actual parameter setting for handover control etc. on the base station might not be able to cater for both scenarios. Therefore uniform performance throughout the distributed antenna system is a key parameter in order to optimize the performance of the indoor coverage system.
