  The performance of centralized and distributed massive MIMO deployments are
analyzed for indoor office scenarios. The distributed deployments use one of
the following precoding methods: (1) local precoding with local channel state
information (CSI) to the user equipments (UEs) that it serves; (2) large-scale
MIMO with local CSI to all UEs in the network; (3) network MIMO with global
CSI. For the distributed deployments (2) and (3), it is shown that using twice
as many base station antennas as data streams provides many of the massive MIMO
benefits in terms of spectral efficiency and fairness. This is in contrast to
the centralized deployment and the distributed deployment (1) where more
antennas are needed. Two of the main conclusions are that distributing base
stations helps to overcome wall penetration loss; however, a backhaul is
required to mitigate inter-cell interference. The effect of estimation errors
on the performance is also quantified.
