Patent ID: 9453919
Filing Date: 2016-09-27
CPC Classification: G01S,H04B

Claim Text:
1. A method for acquiring a Gold sequence (c i ) spreading a signal at a chip rate, said Gold sequence being obtained as a sum of a first M-sequence (x) and a second M-sequence (y i ), the first M-sequence being generated by a first generator polynomial (g x ) and the second M-sequence being generated by a second generator polynomial (g y ), the first and second generator polynomials being of the same degree and a weight of the second generator polynomial exceeds a weight of the first generator polynomial, the method comprising: (a) a step of receiving and sampling at the chip rate said signal to obtain a plurality of samples representative of successive elements of said Gold sequence; (b) a first step of message passing decoding in a first bipartite graph between first variable nodes representing the successive elements of the Gold sequence and first control nodes, each control node being bi-univocally associated with a variable representative of an element of the second M-sequence, edges of the first bipartite graph being determined by coefficients of the first generator polynomial; (c) a step of decimating the variables representative of successive elements of the second M-sequence using a predetermined decimation factor to obtain second variables representative of elements of a third M-sequence, the third sequence (u) being of the same length as the second sequence and being generated by a third generator polynomial having a minimum weight (g (d) a second step of message passing decoding in a second bipartite graph between said second variable nodes and second control nodes, edges of the second bipartite graph being determined by coefficients of the third generator polynomial.