关键词:失步点; 扩频码; 同步; 异步; 盲估计
Approach to blindly estimate spreading sequence of DS-CDMA
MIAO Pu, ZHANG Tian-qi, HUANG Yao, LIU Yan-li
(Chongqing Key Laboratory of Signal & Information Processing (CqKLS&IP), Chongqing University of Posts & Telecommunications, Chongqing 400065, China)
Abstract:According to the problem that the blind estimation of direct spread division multiple access (DS-CDMA) signals’ spreading code was difficult to be obtained in low SNR, this paper proposed a new approach to blindly estimate the spreading code of short code DS-CDMA in synchronous and asynchronous conditions respectively. The approach bases the analysis to the received signals’ feature structure and its correlation matrix’s structure, then used the obtained estimations to deflate the correlation matrix, so could clear its influence to the estimation of the residual signals. Based on the approach, reduced the dimension of the signal subspace at each iteration so that the spreading code and desynchronizing point of the next user could be estimated reliably. At last, completed all the users’ blind estimation. The order of a user signal being estimated is closely related to its power, i.e. the user which has the bigger power is earlier and easier to be estimated. Theoretical analysis and simulation results show that the proposed approach can effectively estimate the spreading code of DS-CDMA. ......