  We propose a location-aware pilot allocation algorithm for a massive
multiple-input multiple-output (MIMO) network with high-mobility users, where
the wireless channels are subject to Rician fading. Pilot allocation in massive
MIMO is a hard combinatorial problem and depends on the locations of users. As
such, it is highly complex to achieve the optimal pilot allocation in real-time
for a network with high-mobility users. Against this background, we propose a
low-complexity pilot allocation algorithm, which exploits the behavior of
line-of-sight (LOS) interference among the users and allocate the same pilot
sequence to the users with small LOS interference. Our examination demonstrates
that our proposed algorithm significantly outperforms the existing algorithms,
even with localization errors. Specifically, for the system considered in this
work, our proposed algorithm provides up to 37.26% improvement in sum spectral
efficiency (SE) and improves the sum SE of the worst interference-affected
users by up to 2.57 bits/sec/Hz, as compared to the existing algorithms.
