The pilot contamination problem has been the primary limitation of massive multiple input
multiple output (MIMO) systems. To improve it, in this paper, we propose a dynamical pilot
assignment algorithm based on the priority of user location. First, we obtain the formulation
of signal to interference plus noise power ratio (SINR) in uplink channel through minimum
mean square error (MMSE) mechanism. Second, an objective function of SINR is defined
together with constraint condition of real distance, based on which optimal value (OV) could …

Pilot contamination can bring up a grave impairment in the performance of massive multiple-
input multiple-output (MIMO) systems. In this paper, an improved time-shifted pilot scheme is
proposed to reduce the pilot contamination, where orthogonal pilots are employed in the
same group to eliminate the residual intra-group interference existing in the original time-
shifted pilot scheme. Meanwhile, the rigorous closed-form expressions of both downlink and
uplink transmission rates with a finite number of antennas are derived, and it is shown that …