Eliminating Pilot Contamination Using Dual Pilot Sequences in Massive MIMO

The uplink transmission in a Massive MIMO system is studied. Pilot contamination during the uplink training is the main inherent limitation that degrades the performance of Massive MIMO. Current approaches are using the same pilot sequences for every cell, leading to the so-called inter-cell interference. In this paper, a novel method that employs dual pilot sequences is proposed where different cells are assigned with different pilot sequences (called them cells' IDs). In particular, each cell has the same set of orthogonal pilot sequences together with a unique pilot sequence (cell's ID). This dual structure mitigates pilot contamination, achieving better channel estimation at various signal-to-noise ratios.