  We propose a novel location-aware pilot assignment scheme to mitigate pilot
contamination in massive multiple-input multiple-output (MIMO) networks, where
the channels are subjected to Rician fading. Our proposed scheme utilizes the
location information of users as the input to conduct pilot assignment in the
network. Based on the location information, we first determine the line of
sight (LOS) interference between the intended signal and the interfering
signal. Our analysis reveals that the LOS interference converges to zero as the
number of antennas at the base station (BS) goes to infinity, whereas for
finite number of antennas at the BS the LOS interference indeed depends on
specific pilot allocation strategies. Following this revelation, we assign
pilot sequences to all the users in the massive MIMO network such that the LOS
interference is minimized for finite number of antennas at the BS. Our proposed
scheme outperforms the random pilot assignment in terms of achieving a much
higher uplink sum rate for reasonable values of the Rician K-factor. Moreover,
we propose a new performance metric, which measures the strength of the LOS
interference and demonstrate that it is a good metric to analyze the
performance of pilot assignment schemes. Theoretical analysis is provided and
verified through numerical simulations to support the proposed scheme.
