System capacity with smart antennas under the presence of angular power spread

Abstract

SUMMARYSmart antennas are a suitable technology to increase the capacity of cellular systems. However, under severe channel conditions, the capacity gain may be small. This work presents a general methodology for the analysis of the effect of the angular power dispersion on the capacity gain for a CDMA system when using smart antennas. System capacity is expressed in terms of a supportable mean number of subscribers per angular sector and it is shown that maximum and mean number of subscribers criteria can be considered equivalent. Formulations for a single cell as well as for multi-tier scenarios are presented. Omni-directional case and non-spread scenarios are shown to be particular cases of the methodology introduced. Capacity is determined for a smart antenna system, both for general antenna beam patterns and general spread characteristics.