Alternating Projections Method for Joint Precoding and Peak-to-Average-Power Ratio Reduction

TL;DR

This paper introduces an alternating projections algorithm for massive MU-MIMO-OFDM systems that jointly reduces peak-to-average power ratio and MU interference, enabling less linear hardware without sacrificing signal quality.

Contribution

The paper presents a novel joint PAR reduction and precoding method based on alternating projections, with a theoretical foundation and simulation validation for massive MU-MIMO-OFDM.

Findings

Significant PAR reduction achieved

Transmit power increase limited

No adverse effects on EVM or OOB emissions

Abstract

Orthogonal frequency-division multiplexing (OFDM) time-domain signals exhibit high peak-to-average (power) ratio (PAR), which requires linear radio-frequency chains to avoid an increase in error-vector magnitude (EVM) and out-of-band (OOB) emissions. In this paper, we propose a novel joint PAR reduction and precoding algorithm that relaxes these linearity requirements in massive multiuser (MU) multiple-input multiple-output (MIMO) wireless systems. Concretely, we develop a novel alternating projections method, which limits the PAR and transmit power increase while simultaneously suppressing MU interference. We provide a theoretical foundation of our algorithm and provide simulation results for a massive MU-MIMO-OFDM scenario. Our results demonstrate significant PAR reduction while limiting the transmit power, without causing EVM or OOB emissions.