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 Jn 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 rn(t) originating from user n and of a term corresponding to the multi-user interference, Jn where r(t)=rn(t)+Jn+n(t) with $r_n\left(t\right)=\sum _{k=1}^{N_p}A_n^ks_n\left(t-{\mathrm{tau}}_n^k\right)$ where Ank and taunk 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, . . . , Nu, n=1, . . . , Nu and n<>m, where Nf is the number of frames, Nc is the number of chips, and Nu 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.