Abstract: For the problem of the blind estimation of asynchronous long code direct sequence-code division multiple access (DS-CDMA) signal pseudo-code sequences under low signal to noise ratio, a blind dispreading method based on nested iterative least squares projection and the library search algorithm is proposed. Firstly, the asynchronous long code DS-CDMA signal is virtualized into a short code DS-CDMA signal containing missing data, and on this basis, the signal is segmented to construct the observation data matrix with overlapping window. Secondly, the mathematical analysis is carried out based on the theory of maximum likelihood estimation, and the spread-spectrum sequence is estimated by the nested iterative least squares projection. Finally, the spread-spectrum sequence is searched in a limited generator polynomial library to estimate the primitive polynomial. Theoretical analysis and simulation results verify the effectiveness of the proposed method.

Key words: asynchronous long code direct sequence-code division multiple access (DS-CDMA), primitive polynomial, nested iterative least squares project, library search