导频信道使得用户站能够获得前向码分多址信道时限,提供相干解调相位参考,并且为各基站提供信号强度比较以确定何时进行切换。 Pilot-frequency channel allows users to gain/get channel time-limit of forward CDMA,provides phase reference for Coherent demodulation and offers BTS comparison regarding signal intensity.As a result ,it can define when to switch. CDMA 技术在中国商用已经三年，得到了飞速的发展。目前中国 CDMA 网络的用户突破了 2300 万用户，成为世界第二大 CDMA 网。 It has been three years since CDMA’s commercial ulitilization ， rapid development has already been achieved .By far,in China,the subscribers who ultilize the network of CDMA has beyond 23 million,making it the second largest CDMA network in the world. 随着网络规模的扩大和用户的不断增加，CDMA 网络建设由开始的以扩大覆盖面积为目标，转移到加强网络优化，提高信号质量上来。 As the size of CDMA networks expands and its subscribers increasingly grow,its construction target has transferred from expanding its coverage into intensity the networking optimization so as to improve the quality of signal. 在一些城市地区，一个载频的容量逐渐不够，开始增加新的载频。相邻的小区之间载频数量不平衡的现象越来越多，不同的频率之间切换的问题开始显露。 As the capacity of a single carrier gradually (insufficient)，so in some urban areas operators start to add new carriers. The signs of carriers imbalance are getting more and more,the switching problems among different frequencies come to light. CDMA 的软切换技术在降低掉话率方面作用明显，但它仅在相同载频之间的切换才能发挥作用。 CDMA’s soft-handoff technology plays an evident/obvious role in reducing calldroprate,however,this technology can switch only owns same carriers. 对于不同载频之间的切换，只能采用硬切换实现。 Hard-handoff is the only way for those different carriers to achieve handoff. 硬切换的成功率...
