A new pilot assignment scheme for mitigating pilot contamination in uplink massive MIMO systems

Abstract Pilot contamination is a serious issue in massive multi-input-multi-output (MIMO) systems which significantly degrades system performance. In this paper, we investigate a new pilot assignment scheme by integrating two-dimensional genetic algorithm (2D-GA) with Tabu-Search algorithm (TS) to mitigate the pilot contamination problem. Firstly, we design a two-dimensional genetic algorithm equipped with elitism strategy as a principal algorithm for solving the pilot assignment problem; then, aiming to enhance the convergence speed of the genetic algorithm to the ideal optimal solution, we integrate TS with the genetic algorithm. This integrated pilot assignment scheme, henceforth designated as GATS-PA, is found to be powerful in mitigating the pilot contamination problem. Numerical simulation results verify that the proposed pilot assignment scheme is very close to the ideal optimal solution with only few number of iterations and outperforms existing methods in terms of enhancing the uplink sum-rate and average rate over a wide range of simulation parameters.