METHOD OF MULTIPLE ACCESS COMMUNICATION IN A CENTRALIZED NETWORK BASED ON AN ULTRA WIDEBAND IMPULSE PHYSICAL LAYER

摘要

Method of multiple access communication in a centralized network based on an ultra wideband impulse physical layer allowing code-based multiple access, each user being associated with a code, the transmission being performed in an asynchronous manner in a propagation medium with multiple paths. It is characterized in that 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; $$ r_n\left(t\right)=\sum _{k=1}^{N_p}A_n^ks_n\left(t-{\tau }_n^k\right)$$ ;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:; $$ \sum _{q=0}^{N_cN_f-1}\left[C_{m,n}^{+2}\left(q\right)+C_{m,n}^{-2}\left(q\right)\right]=N_f^2,\sum _{q=0}^{N_cN_f-1}C_{m,n}^{+}\left(q\right)C_{m,n}^{-}\left(q\right)=0,$$ ;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.