Performance of downlink beam switching for UMTS FDD in the presence of angular spread

We present a simple beam switching scheme to increase the downlink capacity of the UMTS FDD-mode. At the base station, this method only requires one additional transceiver chain, i.e. a separate one for each beam, a beamforming network and a uniform linear array. The mobiles need no changes at all. We analyze the performance of our method by means of system level simulations for different angular spreads. We found an increase in downlink capacity of more than 75% over a conventional 3-sectored system for small direction of departure spreads. Compared to a 6-sectored system our scheme gives a capacity gain of more than 25% for small direction of departure spreads.