  Channel models for massive MIMO are typically based on matrices with complex
Gaussian entries, extended by the Kronecker and Weichselberger model. One
reason for observing a gap between modeled and actual channel behavior is the
absence of spatial consistency in many such models, that is, spatial
correlations over an area in the x, y-dimensions are not accounted for, making
it difficult to study, e.g., area-throughput measures. In this paper, we
propose an algorithm that can distinguish between regions of non-line-of-sight
(NLoS) and line-of-sight (LoS) via a rank-metric criterion combined with a
spiral search. With a k-means clustering algorithm a throughput per region
(i.e., cluster) can be calculated, leading to what we refer to as
"area-throughput". For evaluating the proposed orthogonality clustering scheme
we use a simple filtered MIMO channel model which is spatially consistent, with
known degrees of freedom. Moreover, we employ actual (spatially consistent)
area channel measurements based on spatial sampling using a spider antenna and
show that the proposed algorithm can be used to estimate the degrees of
freedom, and, subsequently, the number of users that maximizes the throughput
per square meter.
