A Triangular Lattice Framework for Massive MIMO Pilot Decontamination Schemes

This paper proposes a distributed framework for simplifying smart pilot signal assignment in cellular massive Multiple-Input Multiple-Output (MIMO) networks, aiming to reduce the complexity of pilot decontamination that comes with high cell count. The framework is based on the Triangular Lattice (TL) structure, tackling the problem of computing pilot assignments for the entire network by dividing it into ’molecules’. These molecules equate to lattice unit cells in a Triangular Lattice pattern for a network with hexagonal cell geometry. Molecules can constitute independent sub-problems by treating each one as a separate network, over which existing pilot assignment methods can be run. The resulting molecule pilot assignments can be efficiently merged to produce assignments for the entire network. In simulations, we show that the application of the TL framework to pilot assignment methods significantly reduces their computational overhead while preserving their efficacy, a trend which scales well with cell count.