Degree of Freedom Analysis For a Holographic MIMO System Based on a Circuit Model

The degree of freedom (DOF) is a key indicator of the spatial multiplexing layers of a wireless channel. Recent studies suggest that the DOF of a multiple-input and multiple-output could be less than the antenna number when strong mutual coupling is considered. To this end, We utilized a mutual-coupling-compliant circuit MIMO model to study the DOF of the holographic MIMO (HMIMO) channel. We showed that a dense array with strong mutual-coupling could support more DOF compared to some popular HMIMO models by numerical simulations.