Articles | Volume 15
Adv. Radio Sci., 15, 181–187, 2017
https://doi.org/10.5194/ars-15-181-2017
Adv. Radio Sci., 15, 181–187, 2017
https://doi.org/10.5194/ars-15-181-2017

  21 Sep 2017

21 Sep 2017

Optimizing the wireless power transfer over MIMO Channels

Karsten Wiedmann and Tobias Weber Karsten Wiedmann and Tobias Weber
  • Institute of Communications Engineering, University of Rostock, Richard-Wagner-Str. 31, 18119 Rostock, Germany

Abstract. In this paper, the optimization of the power transfer over wireless channels having multiple-inputs and multiple-outputs (MIMO) is studied. Therefore, the transmitter, the receiver and the MIMO channel are modeled as multiports. The power transfer efficiency is described by a Rayleigh quotient, which is a function of the channel's scattering parameters and the incident waves from both transmitter and receiver side. This way, the power transfer efficiency can be maximized analytically by solving a generalized eigenvalue problem, which is deduced from the Rayleigh quotient.

As a result, the maximum power transfer efficiency achievable over a given MIMO channel is obtained. This maximum can be used as a performance bound in order to benchmark wireless power transfer systems. Furthermore, the optimal operating point which achieves this maximum will be obtained. The optimal operating point will be described by the complex amplitudes of the optimal incident and reflected waves of the MIMO channel. This supports the design of the optimal transmitter and receiver multiports.

The proposed method applies for arbitrary MIMO channels, taking transmitter-side and/or receiver-side cross-couplings in both near- and farfield scenarios into consideration. Special cases are briefly discussed in this paper in order to illustrate the method.

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Short summary
In this paper, the optimization of the power transfer over wireless channels having multiple-inputs and multiple-outputs (MIMO) is studied. As a result, an optimization framework is proposed, which yields the maximum achievable power transfer efficiency over a given MIMO channel and the corresponding operating point, i.e., the complex amplitudes of the optimal incident and reflected waves. The optimization framework can be used to gain insights in the WPT over arbitrary MIMO channels.