Joint Pilot and Power Assignment to Improve the Fairness of Massive MIMO System

In massive MIMO system, each user has different channel quality, so this paper considers the aspect of improving the system fairness. It carries out both the power assignment and the pilot assignment to improve the spectral efficiency of users with poor channel quality as much as possible. The use of TDD mode in a multi-cell system is considered, and in the uplink two receiver technologies which are maximum-ratio combining (MRC) and zero-forcing (ZF) receiver will be analyzed, respectively. Applying the lower bound of the spectral efficiency to optimize the pilot and data power then joint pilot assignment at the same time, an optimization model to maximize the minimum spectral efficiency which can improve the fairness of the system is proposed. Simulation results verify the effectiveness of the proposed joint assignment scheme.