Evaluation of Downlink Beamforming and Transmission Polarization Adaptation Using a GSM Smart Antenna Demonstrator

Project Type: Master/Diploma Thesis
Student: Doppler Klaus Franz
Mentor: Gernot Kubin


 The application of multi-antenna systems at the base station, so-called Smart Antennas, in cellular mobile communications systems has raised increased interest in recent years. Adaptive base station antennas are supposed to increase the power efficiency, the capacity and the coverage of cellular networks. In this thesis two concepts for multi-antenna transmission from the base station are studied, namely downlink beamforming and transmission polarization adaptation. Downlink beamforming directs the energy transmitted by the base station towards the desired user based on the direction-of-arrival (DOA) estimated from the uplink. Transmission polarization adaptation on the other hand minimizes the loss caused by polarization state mismatch at the receiver by adjusting the transmission polarization based on the polarization state in the uplink. Both concepts were implemented in a multi-antenna prototype and their performance was evaluated by field-trials in a GSM network.