Performance analysis of WCDMA downlink systems with antenna array

The work of the thesis begins with a study of the physical layer tasks of WCDMA systems, including some key techniques and channel structures for both downlink and uplink with an emphasis on the downlink common pilot channel and the time-multiplexed pilot symbol structure. Multipath fading effects and Rake receiver techniques are also covered. These techniques and channel configurations are then used for the simulation of the entire WCDMA downlink system. The second part of this thesis is concerned with antenna array processing techniques and the performance of a two-element antenna that can easily be incorporated into mobile handsets. A simulation study of an antenna array receiver is carried out for various parameters and different combining schemes. The main contribution of the thesis is in the investigation of the downlink performance of a WCDMA system using an adaptive antenna array. Both temporal and spatial diversities are taken into account in the simulation. Based on the WCDMA specification, it is found that the spatial-temporal receiver with n/4 (3.5cm) distance between the antenna elements can provide strong beamforming capability. The diversity gain of a smart antenna system with different combining schemes is also examined. It is shown that when both spatial and temporal signal processing techniques are combined, the multiple access interference and the multipath fading effect can be significantly mitigated or eliminate