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Ｒａｋｅ接收机是ＣＤＭＡ系统中实现多径分集接收的核心部件，而信道估计对其接收性能有很大影响。传统连续导频符号的信道估计是采用对固定区间的信道参数估计值进行平均的方法以抑制接收噪声。但这样必然带来的问题是，如果平均长度过小，则不能达到最大限度地抑制噪声的目的，如果平均长度过大，则又更多地引入了由于多普勒频移所造成的估计误差。因此信道估计的长度必然存在一个与接收噪声及最大多普勒频移有关的一个平衡点。本文提出了直接利用搜索单元得出的最强径所估计出的每个导频符号瞬时信道参数的包络估计最大多普勒频移，并应用于自适应调节信道符号估计长度的方法。仿真表明本方法随着信噪比的增加，能够达到对移动速度的较准确估计。它不仅能够应用于信道估计中，也可应用于自适应调节快速功控步长及小区切换中，具有较高的实用性。
Rake receiver is a core component of CDMA system to achieve multipath diversity reception, and channel estimation has a great impact on its reception performance. The traditional continuous pilot symbol channel estimation adopts the method of averaging channel parameter estimation values in a fixed interval to suppress the receiving noise. However, this inevitably poses the problem that if the average length is too small, the purpose of minimizing noise can not be achieved, and if the average length is too large, more estimation errors due to the Doppler shift are introduced . Therefore, the length of the channel estimation inevitably has a balance between reception noise and maximum Doppler shift. In this paper, the maximum Doppler shift of envelope estimation of instantaneous channel parameters of each pilot symbol estimated by using the strongest path obtained by the search unit is directly proposed and applied to the method of adaptively adjusting the estimated symbol length of a channel. Simulation results show that this method can achieve a more accurate estimation of moving speed with the increase of signal-to-noise ratio. It not only can be applied to channel estimation, but also can be applied to adaptively adjust fast power control step and cell handover, which has high practicability.