  Massive multi-input multiple-out (MIMO) is a key ingredient in improving the
spectral efficiencies for next-generation cellular systems. Thanks to the
channel reciprocity, in time-division-duplexing mode, each base station (BS)
can acquire local channel state information at the transmitter (CSIT) for a set
of users possibly located in adjacent cells. When the small cell BSs equipped
with not-so-many antennas are densely deployed with marcrocells, a simple
noncooperative MIMO precoding technique using local CSIT fails to achieve high
spectral efficiency because of strong inter-cell-interference (ICI). In this
paper, we present a novel noncooperative massive MIMO precoding technique
called signal-to-interference-plus-leakage-plus-noise-ratio (SILNR)
maximization precoding. The key idea of the proposed precoding is to jointly
find a scheduled user set per cell, the beamforming vectors for the users, and
the allocated power by simultaneously mitigating both inter-user-interference
(IUI) and ICI leakage power using local CSIT. To accomplish this, we present a
low-complexity algorithm that finds a local-optimal solution of the
maximization problem for a lower bound of the sum spectral efficiency, i.e., a
non-convex optimization problem. By system-level-simulations, we show that the
proposed precoding method considerably outperforms the existing noncooperative
precoding techniques in terms of the ergodic spectral efficiencies and rate
distributions per user.
