On WCDMA Downlink Capacity with Power Allocation Strategy and Adaptive Antenna Arrays

The base station transmit power is a common resource shared among multiple users in the downlink of WCDMA cellular systems. The overall user capacity decreases if a certain user consumes a large fraction of the base station power. In this work, we investigate the performance gains of adaptive antenna arrays with a power allocation strategy that limits the maximum fraction of transmit power per user. Using adaptive antenna arrays at base stations is a key technique to improve the downlink capacity of WCDMA cellular systems. We consider two adaptive antenna schemes: fixed beam and steered beam. For each scheme, we study the impact on capacity of the proposed power allocation strategy. Uniform linear arrays, uniform circular arrays, and Chebyshev antenna arrays are used to form the beams. The adopted simulation environment supports various types of adaptive antenna arrays, soft/softer handover, and multiple services. Results demonstrate an increase in capacity due to the power allocation scheme, especially when combined with adaptive antenna arrays. A remarkable superiority of the Chebyshev antenna array configuration is shown.