  The energy consumption of wireless networks is a growing concern. In massive
MIMO systems, which are being increasingly deployed as part of the 5G roll-out,
the power amplifiers in the base stations have a large impact in terms of power
demands. Most of the current massive MIMO precoders are designed to minimize
the transmit power. However, the efficiency of the power amplifiers depend on
their operating regime with respect to their saturation regime, and the
consumed power proves to be non-linearly related to the transmit power. Power
consumption-based equivalents of maximum ratio transmission, zero-forcing, and
regularized zero-forcing precoders are therefore proposed. We show how the
structure of the solutions radically changes. While all antennas should be
active in order to minimize the transmit power, we find on the contrary that a
smaller number of antennas should be activated if the objective is the power
consumed by the power amplifiers.
