The optimal throughput of some wireless multiaccess systems

The throughput performance of some multiaccess wireless systems is compared on the basis of the average energy per successfully received information bit E_b/N_o. We prove that, for an optimal choice of the system parameters, some systems are not interference limited and have a similar behavior: at high E_b/N_o they “self-orthogonalize”, i.e., on the average only one user per degree of freedom is active, while at low E_b/N_o they have the same throughput of conventional CDMA, achieved by infinite users per degree of freedom transmitting with vanishing rate