Impact of Mutual Coupling and Antenna Efficiencies on Adaptive Switching Between MIMO Transmission Strategies

Previous research has shown that adaptive switching between multiple-input multiple-output (MIMO) transmission strategies like spatial multiplexing and beamforming increases link reliability and capacity gains, as compared to fixed transmission strategies. To get the full benefit of adaptive switching it is necessary to obtain accurate estimates of the SNR values when we switch between the transmission strategies. In this paper, it is shown that (relatively more) accurate switching point estimates can be obtained by taking into account real-life effects like mutual coupling and antenna efficiencies, for switching between statistical beamforming and spatial multiplexing. Using simulations, it is shown that accounting for these effects can make the switching point estimate more accurate by as much as 12 dB, compared to the case when the practical effects are not considered.