Title :
Blind channel estimation for multi-user CDMA systems
Author :
Aktas, Emre ; Mitra, Urbashi
Author_Institution :
Dept. of Electr. Eng., Ohio State Univ., Columbus, OH, USA
Abstract :
Blind identification of digital communication channels has attracted a significant amount of attention. In this work, subspace-based methods are considered specifically for direct-sequence/code-division multiple-access (DS/CDMA) signals in an asynchronous, multipath, multi-user environment. The objective is to reduce the complexity of previously proposed methods by exploiting the properties of DS/CDMA waveforms. In particular, knowledge of the DS/CDMA spreading codes is employed, via matched filtering, to reduce the dimensionality. The resulting algorithm shows negligible difference in performance with respect to a previously proposed algorithm by Torlak and Xu (see IEEE Trans. on Signal Processing, vol.45, no.1, p.137-47, 1997). However, the reduction in complexity can be significant. The Cramer-Rao lower bounds on the estimation variance are determined and provide further justification for the matched filtering scheme
Keywords :
code division multiple access; computational complexity; digital radio; filtering theory; matched filters; multipath channels; parameter estimation; pseudonoise codes; spread spectrum communication; Cramer-Rao lower bounds; DS/CDMA signals; DS/CDMA waveforms; algorithm; asynchronous environment; blind channel estimation; complexity reduction; digital communication channels; dimensionality reduction; direct-sequence/code-division multiple-access; estimation variance; matched filtering; multi-user CDMA systems; multipath; performance; spreading codes; subspace-based methods; Blind equalizers; Digital communication; Digital filters; Electromagnetic propagation; Filtering; Interference; Matched filters; Multiaccess communication; Signal processing; Wireless communication;
Conference_Titel :
Communications, 1998. ICC 98. Conference Record. 1998 IEEE International Conference on
Conference_Location :
Atlanta, GA
Print_ISBN :
0-7803-4788-9
DOI :
10.1109/ICC.1998.685174