EMF-Aware Power Control for Massive MIMO: Cell-Free versus Cellular Networks

TL;DR

Simulation results prove that EMF safety restrictions can be easily met without jeopardizing the minimum data rate, that the CF-mMIMO outperforms the multi-cell massive MIMO deployment, and that the proposed power control strategy greatly improves the system fairness.

Abstract

The impressive growth of wireless data networks has recently led to increased attention to the issue of electromagnetic pollution. Specific absorption rates and incident power densities have become popular indicators for measuring electromagnetic field (EMF) exposure. This paper tackles the problem of power control in user-centric cell-free massive multiple-input-multiple-output (CF-mMIMO) systems under EMF constraints. Specifically, the power allocation maximizing the minimum data rate across users is derived for both the uplink and the downlink under EMF constraints. The developed solution is also applied to a cellular mMIMO system and compared to other benchmark strategies. Simulation results prove that EMF safety restrictions can be easily met without jeopardizing the minimum data rate, that the CF-mMIMO outperforms the multi-cell massive MIMO deployment, and that the proposed power control strategy greatly improves the system fairness.

Figures (5)

• Figure 1: Illustrative example of a user-centric CF-mMIMO setup with $K = 14$ users and $M = 9$ APs equipped with $3$ antennas. In this case, users are connected to only $N = 2$ APs.
• Figure 2: Illustrative example of a MC-mMIMO setup with $K = 14$ users and $L = 3$ multi-antenna BSs. Unlike cell-free, users are connected to only one BS (dashed lines indicate cell borders).
• Figure 3: DL user rate under (a) CF-mMIMO and (b) MC-mMIMO with UPC, PPC, and OPC.
• Figure 5: UL user rate under (a) CF-mMIMO and (b) MC-mMIMO with UPC, FPC, and OPC.
• Figure 7: UL user rate under (a) CF-mMIMO and (b) MC-mMIMO with OPC for different $E_{k,n}$.