非理想信道估计下最大比合并的实现

在信道估计理想和各分支具有相等噪声功率的分集系统中,利用信道估计的共轭作为合并系数的传统最大比合并是最优的合并方法.然而在实际的宽带码分多址系统中,由于Rake接收机每个指峰上的噪声功率是不等的,且信道估计也是非理想的,所以传统的最大比合并实现方法并不是最优的.针对这种情况,本文研究了一种改进最大比合并实现方法在宽带码分多址系统中的应用.仿真表明它比传统的最大比合并实现方法更适合实际的宽带码分多址系统.

Implementation of maximum ratio combining with imperfect channel knowledge

Conventional Maximum Ratio Combining(MRC) using conjugate of channel estimation is considered the optimal combining scheme when fading parameters can be perfectly tracked and different diversity branches have equal noise power.However,in practical wideband code division multiple access(wideband CDMA) system,it is not the optimal scheme because of the unequal noise power and imperfect channel estimates in different Rake fingers.In this paper,the implementation of a modified MRC scheme,which is more suitable for Rake receiver in wideband CDMA system than the conventional MRC scheme,in wideband CDMA system is investigated and the enhanced performance is demonstrated by computer simulations.