Pilot contamination elimination in massive MIMO systems

Abstract

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 be achieved. Third, we propose a novel cellular classification algorithm, that is, area with better channels adopts random pilot assignment scheme, and others use the novel algorithm. Last, the proposed algorithm is compared with the traditional algorithm. The results show that the proposed algorithm can effectively reduce the influence of pilot contamination on the communication performance and improve the system SINR and the system capacity.