Fast Power Allocation Technique for Downlink Transmission in Cell-Free Massive MIMO Systems

Abstract

In this paper, we study power allocation techniques for the downlink in cell-free (CF) massive multiple-input multiple-output (mMIMO) systems. In such systems, choosing the optimal power allocation plays an important role in maximizing the achievable data rate and guaranteeing fairness among the users. However, this optimization problem is typically non-convex with an iterative computationally-expensive solution. This paper presents two new formalizations of the power allocation problem using duality. The dual problems have smaller solution spaces that would yield a fast, less-complex power allocation without any performance compromise. Simulation results show the solution to the dual problems produces the same per-user achievable capacity of the upper bound obtained using the classical bi-section method.