Simple way? Its to increase te receiver sensitivty of GSM Antenna we use.
Detail: Antenna s havin its own limitation to shoot the RF signal to a cerain limit and certain angle. Where as a mobile will be in any distance or in any angle depending on the users wish, now as an operator we need to give the maximum support to the subsrciber. Now takin a single sector we will try to capture the maximum signal sent out by mobile. This is by:
1. Space diversity
2. Polarization Diversity
Space Diversity means to keep 2 antennas for same sector at a distance of 3dB maximum.
Polarization Diversity means keepin the polarization of the plates inside the antenna tilted in such a way that the sensitivity will be at max. Mostly it will be at -45, +45 degrees.
Hope am right, and hope u r clear.