  Wireless cellular communication networks are bandwidth and interference
limited. An important means to overcome these resource limitations is the use
of multiple antennas. Base stations equipped with a very large (massive) number
of antennas have been the focus of recent research. A bottleneck in such
systems is the limited number of transmit/receive chains. In this work, a
line-of-sight (LOS) channel model is considered. It is shown that for a given
number of interferers, it suffices that the number of transmit/receive chains
exceeds the number of desired users by one, assuming a sufficiently large
antenna array. From a theoretical point of view, this is the first result
proving the near-optimal performance of antenna selection, even when the total
number of signals (desired and interfering) is larger than the number of
receive chains. Specifically, a single additional chain suffices to reduce the
interference to any desired level. We prove that using the proposed selection,
a simple linear receiver/transmitter for the uplink/downlink provides
near-optimal rates. In particular, in the downlink direction, there is no need
for complicated dirty paper coding; each user can use an optimal code for a
single user interference-free channel. In the uplink direction, there is almost
no gain in implementing joint decoding. The proposed approach is also a
significant improvement both from system and computational perspectives.
Simulation results demonstrating the performance of the proposed method are
provided.
