Patent ID: 8116349

Claim:
A method of multiple access communication in a centralized network based on an ultra wideband impulse physical layer allowing multiple access based on time-hopping codes, each user being associated with a code, the transmission being performed in an asynchronous manner in a propagation medium with multiple paths, wherein a criterion is established so as to find the codes of the Nu various users making it possible to minimize the variance of the multi-user interference J n at the output of a linear receiver, the signal received r(t) originating from a user being expressed in the form of a sum of the signal of interest r n (t) originating from user n and of a term corresponding to the multi-user interference, J n where r ( t )= r n ( t )+ J n +n ( t ) with r n ⁡ ( t ) = ∑ k = 1 N p ⁢ A n k ⁢ s n ⁡ ( t - τ n k ) where A n k and τ n k are respectively the amplitude and the delay of the kth path of the transmission channel between user n and the receiver, and in that to determine the codes of the users use is made of the partial cyclic inter-correlations of the codes which satisfy the following criteria: ∑ q = 0 N c ⁢ N f - 1 ⁢ [ C m , n + 2 ⁡ ( q ) + C m , n - 2 ⁡ ( q ) ] = N f 2 , ∑ q = 0 N c ⁢ N f - 1 ⁢ C m , n + ⁡ ( q ) ⁢ C m , n - ⁡ ( q ) = 0 , for m=1, . . . , N u , n=1, . . . , N u and n≠m, where N f is the number of frames, N c is the number of chips, and N u is the number of users transmitting to the central point or the number of point to point links simultaneously transmitting in a point to point centralized network, where C + m,n (q) and C − m,n (q) are the cyclic partial correlations between the developed codes of users m and n, defined by: C m , n - ⁡ ( q ) = ∑ k = 0 q - 1 ⁢ c m ⁡ ( k ) ⁢ c n ⁡ ( k - q ) , ⁢ and C m , n + ⁡ ( q ) = ∑ k = q N c ⁢ N f - 1 ⁢ c m ⁡ ( k ) ⁢ c n ⁡ ( k - q ) .