WCDMA软切换中的下行功率控制方案

Downlink Power Control Schemes in Soft Handoff of WCDMA

发射功率控制是CDMA系统的关键技术之一。在WCDMA的软切换中 ,传统下行链路功率控制方案的实现主要存在两个问题 :基站发射功率的失衡和下行链路干扰的增大。为解决上述问题 ,本文介绍三种新的下行功率控制方案 :降低TPC频率功率控制、调整环功率控制和站选择分集发射功率控制。其中前两种方案用于恢复软切换中基站发射功率的平衡 ,而最后一种方案用于减小下行链路干扰。研究表明 ,利用上述方案能够有效减小软切换中基站发射功率的差异或下行链路干扰 。

Transmit power control is one of the key techniques in CDMA systems.During the soft handoff of WCDMA,there are mainly two probˉlems in implementing the conventional downlink power control schemes.They are the unbalance of the bases transmitted powers and the increase of downlink interference.In order to overcome these problems,we introduce three newdownlink power control schemes:reducing TPC frequency power control,adjustment loop power control and site selection diversity transmission power control.Among the three schemes,the first two are used to restore the balance of the bases transmitted power in soft handoff,and the last one is used to reduce the downlink interference.It is shown that the differences of the bases transmitted powers or the downlink interference in soft handoff are reduced effectively with these schemes,and thus the system capacity is improved.