中文摘要：

在高斯误差和Doppler扩展条件下，研究信道估计时公共导频信道相关长度对天线阵的合并性能影响。假设信道估计通过相关WCDMA公共导频信道的N个符号来获得，文章首先推导了相干BPSK解调时平均BER性能的闭解表达式，然后利用该平均BER表达式对导频信道最优相关长度进行了分析，给出了最优相关长度的计算方法，并证明了最优相关长度N只与最大Doppler扩展fd和符号周期有关，与阵列参数以及天线接收的信噪比无关。

英文摘要：

Maximum-ratio combining （MRC） is a simple and effective combining scheme for adaptive antenna arrays to combat fading. However, it requires estimation of the spatial signature （ i. e., the channel gain and phase at each antenna element） of the desired signal across the array. Assuming the channel estimation is obtained by N symbols＇ correlation using common pilot channel （CPICH）, we proceed to develop a fully analytical assessment of the impacts of Gaussian error and Doppler spread on the MRC performance. The originality of the approach revolves around the derivation of the closed-form expression for average bit error probability for coherent BPSK. The expression is then applied to find the optimal correlation length of channel estimation. As a result,the computing method of optimal correlation length has been given. It is also proved that the optimal correlation length N was only correlative with maximal Doppler spread fd and symbol duration.