A model with electric fields for the inclusion of mutual coupling effects in the MIMO channel

Multiple input multiple output (MIMO) wireless communication systems have been a focus of interest, due to their ability to increase the capacity in rich scattering environments by using multi-element antenna arrays both at the transmitter and the receiver sides. However, when dealing with multi-element antenna arrays, effects of mutual coupling among the array elements become significant and should be included in the channel matrix properly. These effects were included in the MIMO channel matrix mainly for free standing linear arrays (FSLA) of uniform thin-wire dipole antennas using coupling matrices obtained from the mutual interaction matrix and terminations. These matrices reduce to the identity matrix when the interactions are ignored, because of the scaling factors related with termination impedances. Therefore, in this paper we propose a partially stochastic full-wave electromagnetic model with electric fields (MEF), to evaluate the MIMO channel matrix accurately with and/or without including effects of mutual coupling. Effects of mutual interactions among the array elements through space and surface waves (when printed arrays are considered) are included in the channel matrix using a full-wave hybrid method of moments (MoM)/Green´s function technique. The stochastic part of the model comes from a local cluster of uniformly distributed scatterers. Consequently, the proposed method is exact except the scatterer scenario, thus, besides achieving the accuracy to be used as a benchmark solution for other approaches, comparisons can be made among any kind of arrays.