Impact of mutual coupling on capacity in large MIMO antenna arrays

Abstract

It is well known that the wireless network spectral efficiency in a multipath environment can be increased by means of spatial multiplexing. By using propagation channel models it is possible to simulate and estimate the spectral efficiency. Winner II is to this date one of the most popular propagation channel models. It uses the geometric stochastic approach to model multipath channel properties for various types of environments such as urban, suburban, and indoor. However, the Winner II model does not take antenna coupling into account. Mutual coupling can be modeled by multiplying the channel matrix H by a coupling matrix C, but the question is how to calculate this coupling matrix? In this paper we introduce a method to calculate the coupling matrix and analyze this with the Winner II model.

Downlink Spectral Efficiency of Massive MIMO Systems with Mutual Coupling

“…Therefore, it is crucial to investigate the antenna mutual coupling effect in terms of modeling, mitigation, and theoretical analysis of the effect of mutual coupling on largescale antenna array processing techniques. The conventional mutual coupling modeling methods include the impedance matrix-based methods [10][11][12][13] and scattering parameter (S-Parameter)-based methods [14,15]. Apart from these, new methods such as the deep learning-based method [16] have been presented in recent years.…”

“…• In contrast to [12,14,16], the mutual coupling effect on the performance of multi-user massive MIMO systems has been investigated in this paper. Moreover, we also address the multi-cell issues, which are rarely covered in previous papers.…”

“…As for the mutual coupling effect modeling, in contrast to the S-parameter-based method in [14] and the simulation plus impedance matrix-based in [23], which are highly reliant on the specific antenna array design and modeling, the impedance matrix-based method chosen in this paper can be utilized to perform the theoretical performance analysis of massive MIMO systems. In that case, closed-form expressions of SINRs can be driven.…”

“…In contrast to [14,16,23], the closed-form SINR expressions and corresponding lower bound of channel capacity is obtained based on the impedance matrix-based mutual coupling effect modeling. Especially, we give the closed-form SINR expression for maximal ratio transmission (MRT) combining based on the MMSE estimator.…”

Active reflection coefficients characterization system for multiple input multiple output antennas

“…To achieve higher spectral efficiency in terms of transmission, the radiated signal can be sent directly to the target using beamforming. This technique is widely used in MIMO systems, since it enables to transmit different power levels to different users [4] and, subsequently, the energy consumption may be reduced, accordingly. By adding more elements to a MIMO antenna array, the signal-to-noise ratio will increase due to the higher antenna gain, and hence, the possibility to achieve higher spectral efficiency.…”