Capacity of UMTS-FDD-based cellular systems with smart antennas in presence of position and alignment errors

The capacity of a WCDMA-based cellular system like a UMTS-FDD network can be highly improved by utilizing the smart antenna concept. The received signal power of each link in the entire network can be increased by employing antenna arrays at the base station side and performing beamforming. Since the characteristics of a single antenna element have a strong influence on the amount of achievable capacity improvement, close-to-reality investigations on the network capacity must incorporate realistic antenna element characteristics. In this contribution, a UMTS-FDD network equipped with smart antennas at the base stations is analyzed on system level. Thereby, the focus lies on the impact of uncertainties in antenna position and alignment on the network capacity. Furthermore, the effect of different uplink and downlink carrier frequencies on the beamforming performance is analyzed. A simplified beamforming approach to overcome this effect is presented.