  In the conventional multiuser MIMO systems, user selection and scheduling has
previously been used as an effective way to increase the sum rate performance
of the system. However, the recent concepts of the massive MIMO systems (at
centimeter wavelength frequencies) have shown that with higher spatial
resolution of antenna arrays different users in the dense scenarios can be
spatially separated. This in turn significantly reduces the signal processing
efforts required for multiuser selection algorithms. On the other hand, recent
measurements at millimeter wave frequencies show that multipath components only
arrive from few angular directions leading to high spatial correlation between
the paths and co-located users. This paper focus at the investigation of
spatial separation among the users at the millimeter wave frequencies with
fully digital linear zero-forcing transmit precoding considering various
channel propagation parameters. Our analysis results convincingly give a proof
that multiuser selection algorithms are still important for millimeter wave
communication systems. Results also show that increased number of antenna
elements does not give a major benefit to sum rate improvements as compared to
the selection of correct number of users to be selected/scheduled.
