Precoding under Instantaneous Per-Antenna Peak Power Constraint

TL;DR

This paper explores precoding strategies for multi-user MISO downlink systems with nonlinear PAs, allowing for instantaneous power constraints to improve efficiency while maintaining BER performance.

Contribution

It introduces linear and nonlinear precoder designs that mitigate multi-user interference under per-antenna peak power constraints, relaxing the constant envelope requirement.

Findings

Achieves BER performance comparable to constant envelope systems with less transmitted power.

Reduces PA power consumption through optimized precoding under peak power constraints.

Demonstrates effectiveness of proposed precoders via simulation results.

Abstract

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.