Blind Despreading of Non-periodic Long Code Direct-Sequence Spread-Spectrum Signals

In this paper, the processing of delay and multiplication is utilized to eliminate the influence of the information code on long code sequence and short code sequence and the signal is segmented in an ingenious way, and a subsection cross-correlation method to descramble is proposed to obtain the long code sequence of non-periodic long code direct sequence spread spectral (NPLCDS-SS) signals by using the shift-and-add property of m-sequence. The primitive polynomial of the short code is estimated by using the matrix’s oblique elementary method and the information code synchronization is realized by utilizing the information code blind synchronization method based on covariance norm. Finally a dispreading method of NPLCDS-SS signal is obtained. Simulations results shown that the bits error rate of this method is below 10^-2, when the signal-to-noise ratio is greater than 3.6dB and the signal length is only one-eighth of the period of the long code sequence.