Statistical evaluation of outdoor-to-indoor office MIMO measurements at 5.2 GHz

In this paper, we present a statistical evaluation of an outdoor-to-indoor multiple-input multiple-output (MIMO) measurement campaign performed at 5.2 GHz. 159 measurement locations in an office building are analyzed. Our analysis pays special attention to two key assumptions that are widely used in stochastic channel models. An assumption that is used in practically every channel model is that the channel can be represented as a sum of a line-of-sight (LOS) component plus a (possibly correlated) zero-mean complex Gaussian distribution. Our investigation shows that this model does NOT adequately represent our measurement data. Our analysis also highlights the difference between the LOS power factor and the Rician K-factor. We show that the direction-of-arrival (DOA) spectrum depends noticeably on the direction-of-departure (DOD). Therefore, the popular Kronecker model is not applicable, and the more general Weichselberger model should be used.