Signal enhancement in a near-field MIMO environment through adaptivity on transmit and polarization diversity

In this paper a technique is presented on how to enhance the received signals in a near field multi-input multi-output (MIMO) environment where beam forming is not possible. This is done through the use of adaptivity on transmit. Polarization diversity can also be implemented. This technique is based on the principle of reciprocity, is independent of the material medium in which it is transmitting, and incorporates near-field environments and multipath. The objective here is to select a set of weights adapted to each receiver to be applied to each transmitting antenna array, which is a function of the user location, so that the transmitted signal at the carrier frequency may be directed to a particular receiver location while simultaneously minimizing the received signal strengths at other receiver locations. Numerical simulations have been made to illustrate the novelty of the proposed approach.