Downlink radio resource optimization in wide-band

Summary Soft handover is analysed and optimized in the downlink direction of a WCDMA system in this paper. Downlink is chosen because the asymmetric nature of most new services supported by the next generation of mobile networks requires more capacity in that direction, and so this is likely to be the limiting factor. The study also sets out to resolve the often controversial opinions about the system level performance with soft handover in the downlink direction. Here, the performance of soft handover is investigated on the link level and on the system level separately. Apart from power control, the cell-selection scheme and power limits (which are ignored by most of the previous work in the literature) are also included. Results show that from the point of view of link quality, soft handover can prevent the downlink traffic channel power going beyond the power limit. From the system level point of view, the downlink capacity can be increased by choosing a proper soft handover overhead. The optimum value of the overhead depends closely on the cell-selection threshold and the radio environment. The paper proves that soft handover is an effective way for interference-reduction and radio resource optimization in the downlink direction for WCDMA systems. Copyright # 2003 John Wiley & Sons, Ltd.