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



Ramya Bhagavatula, Robert. W. Heath Jr, Antonio Forenza, Nicholas J. Kirsch,and Kapil Dandekar .


Wireless Personal Communications Journal DOI: 10.1007/s11277-008-9513-2, May, 2008.


Adaptive switching between multiple-input multiple-output (MIMO) transmission strategies like diversity and spatial multiplexing yields significantly higher capacity gains over fixed transmission schemes. It is desirable to obtain accurate estimates of the switching points between these transmission schemes, to realize the capacity gains made possible by adaptive switching. In this paper, it is shown that the accuracy of switching point estimates for switching between statistical beamforming (SBF) and spatial multiplexing (SM) is improved significantly, by taking mutual coupling effects into account. The impact of mutual coupling on the ergodic capacities of SBF and SM is analyzed, by deriving expressions for the same. Adaptive switching between combinations of transmission strategies and antenna array configurations is shown to produce maximum capacity gains. Expressions for the switching points between transmission strategies and/or antenna configurations, including mutual coupling effects, are derived and used to explore the influence of mutual coupling on the estimates.


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