Comparison and optimization of antenna concepts for downlink beamforming

Downlink beamforming is optimized for cellular radio systems with frequency division duplex (FDD). System level simulations clarify what gain can be achieved by applying circular arrays in contrast to linear arrays with sectorizing antenna elements. In the case of circular arrays, omnidirectional as well as sectorizing antenna elements are considered. The latter topology corresponds to the most realistic situation where antenna arrays are mounted below the top of a base station tower so that the individual antenna elements cannot exhibit an omnidirectional antenna pattern. Furthermore, antenna array parameters, such as element spacing and beamwidth of the sector antennas, are optimized.