  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.
