Blind Space-Time Channel Estimation and Multiuser Detection for Asynchronous DS-CDMA System
异步DS-CDMA系统盲空时信道估计及多用户检测

The blind space-time channel estimation and multiuser detection algorithm for asynchronous DS-CDMA system in frequency selective Rayleigh fading channel are presented. By investigating the code space of the multipath signals and the data vector space, the noise-subspace-based approach is used to perform blind channel parameter estimation in the asynchronous DS-CDMA system. The method exploits not only the characteristics of multipath propagation but also the characteristics of timing-offsets which may occur in the receiver, to facilitate the application of a blind linear filter-optimization technique to robust interference suppression. A modified ULV updating algorithm is applied to performing noise subspace tracking. The algorithm does not require rank estimation of the correlation matrix, and estimate directly the noise subspace without tracking the signal subspace. Furthermore, Linearly Constrained Minimum Variance (LCMV) blind space-time multiuser detection and its adaptive implementation based on Householder-transform constrained least-mean-square (HCLMS) algorithm is considered. Simulation results show the effectiveness of the proposed algorithms.