  In this paper, we investigate the system performance of a multi-cell
multi-user (MU) hybrid millimeter wave (mmWave) multiple-input multiple-output
(MIMO) network adopting the channel estimation algorithm proposed in [1] for
channel estimation. Due to the reuse of orthogonal pilot symbols among
different cells, the channel estimation is expected to be affected by pilot
contamination, which is considered as a fundamental performance bottleneck of
conventional multicell MU massive MIMO networks. To analyze the impact of pilot
contamination on the system performance, we derive the closed-form
approximation expression of the normalized mean squared error (MSE) of the
channel estimation performance. Our analytical and simulation results show that
the channel estimation error incurred by the impact of pilot contamination and
noise vanishes asymptotically with an increasing number of antennas equipped at
each radio frequency (RF) chain deployed at the desired BS. Thus, pilot
contamination is no longer the fundamental problem for multi-cell hybrid mmWave
systems.
