Patent ID: 6910006

Claim:
A method of decoding a received sequence α=(α 1 , . . . , α n ) where, for any integer i between 1 and n, n being an integer greater than 1, α i is the received electrical signal corresponding to the transmission of an electrical signal a i representing the i th binary element v i of a word chosen in a binary code C of words v=(v 1 , . . . , v n ) satisfying v·h T =0, where h is a row n-tuplet on the set {0,1} whose number of 1 is denoted w, where T represents the transposition and the scalar product v·h T is calculated modulo 2, said decoding method including a step consisting of determining extrinsic information on each of the binary elements of v covered by h, said extrinsic information given on the i th binary element of v, assumed to be covered by h, being the quantity ρ ext [A ( i,h )]= P[a i =−1 |A ( i,h )]/ P[a i =+1 |A ( i,h )], where A(i,h) is the set of received values α j of α which are covered by h, with the exception of α i , and where P[a i |A(i,h)] is the probability, calculated on the basis of the received signals α j of A(i,h), that the i th signal transmitted was a i , said decoding method being characterised in that the determination of the extrinsic information is effected by means of the formula ρ ext [A ( i,h )]=[ S 1 ( i )+ S 3 ( i )+ . . . ]/[1 +S 2 ( i )+ S 4 ( i )+ . . . ] where the numbers S r (i), for any integer r between 1 and w−1, are calculated by applying the recurrence r - 1 ⁢ ∑ i = 1 w ⁢ z α i ⁢ S r - 1 ⁢ ( i ) - z α j ⁢ S r - 1 ⁢ ( j ) = S r ⁢ ( j ) to the numbers S 0 (i) initialised to 1, with z=exp(−4E/N), where E is the energy of the transmitted signals a i and N is the spectral power density of the noise on the transmission channel.