Downlink Performance of Uplink Fractional Power Control in 5G Massive MIMO Systems

Uplink power control is an efficient scheme to mitigate pilot contamination in massive multiple-input multiple-output (MIMO) systems. By properly reducing the power of some user equipment (UE) devices during the transmission of their pilot sequences, better channel estimation can be performed at the base stations (BSs), which, in turn, positively affects system performance. In this work, we study the effects of fractional power control (FPC) on the downlink performance of the most relevant massive MIMO deployments by performing extensive system simulations based on the most recent three dimensional spatial channel model released by the 3rd Generation Partnership Project. Numerical results comparing different pilot reuse factors, beamforming criteria and BS array sizes indicate the most suitable tuning of the FPC parameters and show that optimized FPC provides huge gains in the cell border throughput when compared to a baseline scheme with all the UEs transmitting at maximum power. Moreover, the stronger the pilot contamination in a deployment or setup is, the higher the gain that FPC provides.