Gain design and power allocation for overloaded MIMO-OFDM systems with channel state information and iterative multiuser detection

This paper deals with multiuser MIMO-OFDM systems in which single-antenna users transmit encoded data to a common receiver employing iterative multiuser detection. We focus on uplink communications in overloaded scenarios, i.e. the feasibility for the system to support a number of users larger than the number of receive antennas. We assume that perfect channel state information is available at the receiver, and perfect, analog and instantaneous feedback from the receiver to the users. We show how simple power allocation at user location, based on gain design for asymptotic separation at receiver location, makes overloading feasible. Numerical simulations show the benefit of the proposed approach.