Blind Estimation of PN Sequence Based on FLO Joint M Estimation for Short-Code DSSS Signals

When using a singular value decomposition (SVD) algorithm to estimate the pseudo code sequence of shortcode direct sequence spread spectrum (DSSS) signals directly under impulse noise, the pseudo code information extracted by the algorithm will be seriously interfered, and the estimation performance will deteriorate obviously. In this paper, proposed is a pseudo code sequence blind estimation algorithm based on fractional low order(FLO) joint M estimation. Under the condition of known pseudo code rate and pseudo code period, the received signal is segmented by the size of double PN period, and the fractional low order matrix of the received signal is constructed by using this algorithm in order to reduce the noise component, and then the matrix is decomposed by the SVD algorithm. By taking the summation and subtraction operation between the absolute value of the principal component and its complement sets to estimate the position of the out-of-step point of the pseudo code. Finally, the blind estimation of a pseudo code sequence is realized. Simulation results show that the proposed algorithm can greatly improve the performance of pseudo code sequence blind estimation in an impulse noise channel. When the signal-to-noise ratio (SNR) is about -5 db, the accuracy of the]pseudo code estimation can be kept above 90%.