RAKE接收机常被超宽带（UWB）系统用来收集信号的能量和减小信号衰落。本文从缩短信道时延扩展的角度出发，研究RAKE接收机的部分信道均衡能力。本文推导出了RAKE接收机均衡性能与RAKE接收机的复杂度和信道衰减系数之间的关系；分析了信道估计误差对RAKE接收机合并前后多径信道变化的影响。研究表明当存在估计误差时，RAKE接收机仍然能实现缩短信道的作用，但是性能有所下降；由于低复杂度RAKE接收机引入的估计误差较少，在低信噪比条件下其缩短信道性能甚至会优于高复杂度的RAKE接收机。

A multi-symbol detection (MSD) method based on the approximation of ML decoding for detecting the signal modulated by PPM in unknown UWB channels is proposed. The explicit expression of the achievable rates of PPM with MSD is derived, from which we study the relationship between the achievable rates, SNR and channel bandwidth. The numerical results show that multi-symbol detection significantly improves the achievable rates over conventional non-coherent detection. When channel bandwidth tends to infinity, as long as symbol number N keeps up with the resolvable multipath number L, the achievable rates will tend to AWGN capacity.

The iterative algorithm for minimum variance distortion- less response filter based on auxiliary-vector (IMVDR-AV) is generalized in this paper from different perspective. By extending the optimization criteria on filter design, it is generalized to an iterative algorithm of linear constrained minimum power filter (ILCMP-AV). Starting from this algorithm, we present an iterative algorithm of LCMP filter based on local optimization criterion (ILCMP-LOC) which converges rapidly by further generalizing the conditional optimization criterion on weighting coefficient computation. For any positive definite input auto- correlation matrix and any linear constraint, the ILCMP-AV algorithm recursively generates a sequence of auxiliary vectors by maximizing the magnitude cross correlation under some constraint conditions and its corresponding weighting coefficients by minimizing the filter output variance. Theoretical analysis illustrates that the combination of the updated filters and the weighted auxiliary vectors forms a sequence of filters that converges to the LCMP solution.