Experimental evaluation of polarisation diversity gain at the base station end in a GSM900 network

Horizontal space diversity is traditionally used to reduce fading problems at the base station end in mobile networks. An attractive alternative to improve the nonideal radio channel is to use polarisation diversity. The aim of this paper is to evaluate experimentally polarisation diversity gain at the base station end in an operating GSM900 network. The measurements were performed in the city of Lahti, Finland. Polarisation diversity gain was evaluated in three different area types. In urban area the horizontal/vertical (HV) or ±45° slanted antenna configurations were used at the receiving end. In suburban and rural areas the study concentrated on comparing the performance of the ±45° slanted antenna configuration and the horizontal space diversity case. The obtained results show that the system performance with space diversity and with polarisation diversity is nearly equal. Furthermore, if it is not possible to provide adequate separation for the space diversity configuration the polarisation diversity scheme can outperform the space diversity scheme