What makes a good MIMO channel model?

Using different meaningful measures of quality, the paper investigates the accuracy of analytical MIMO channel models. Different metrics should be applied if the underlying MIMO channel supports predominantly beamforming, spatial multiplexing or diversity. The number of envisaged antennas plays an important role. By comparing the results of an extensive indoor measurement campaign at 5.2 GHz, we find the following main conclusions: (i) the recently developed Weichselberger model predicts capacity for any antenna number and represents diversity best of all three models, but still not satisfactorily; (ii) except for 2×2 MIMO systems, the Kronecker model fails to predict capacity, joint angular power spectrum, and diversity; (iii) the virtual channel representation should only be used for modeling the joint angular power spectrum for very large numbers of antennas. The answer to the question posed in the title: the appropriate model has to be chosen according to the considered application.