  We consider a multi-user (MU) multiple-input-single-output (MISO) downlink
system with M single-antenna users and N transmit antennas with a nonlinear
power amplifier (PA) at each antenna. Instead of emitting constant envelope
(CE) signals from the antennas to have highly power efficient PAs, we relax the
CE constraint and allow the transmit signals to have instantaneous power less
than or equal to the available power at each PA. The PA power efficiency
decreases but simulation results show that the same performance in terms of
bit-error-ratio (BER) can be achieved with less transmitted power and less PA
power consumption. We propose a linear and a nonlinear precoder design to
mitigate the multi-user interference (MUI) under the constraint of a maximal
instantaneous per-antenna peak power.
