Nonlinear Multi-Carrier System with Signal Clipping: Measurement, Analysis, and Optimization

TL;DR

This paper analyzes the effects of signal clipping and PA nonlinearity in OFDM systems, deriving expressions for SNR and SER, and proposes optimal system settings to minimize errors considering both distortions.

Contribution

It introduces a Bessel-Fourier PA model and derives system performance metrics, enabling joint optimization of clipping and PA nonlinearity effects in OFDM.

Findings

Derived SNR and SER expressions for clipped OFDM with nonlinear PAs.

Identified optimal system parameters to minimize SER.

Provided a framework for system-level optimization considering both distortions.

Abstract

Signal clipping is a classic technique for reducing peak-to-average power ratio (PAPR) in orthogonal frequency division multiplexing (OFDM) systems. It has been widely applied in consumer electronic devices owing to its low complexity and high efficiency. Although clipping reduces the nonlinear distortion caused by power amplifiers (PAs), it induces additional clipping distortion. Optimizing the joint system performance with consideration of both PA nonlinearity and clipping distortion remains an open problem due to the complex PA modeling. In this paper, we analyze the PA nonlinearity through the Bessel-Fourier PA (BFPA) model and simplify its power expression using inter-modulation product (IMP) analysis. We derive expressions of the receiver signal-to-noise ratio (SNR) and system symbol error rate (SER) for the nonlinear clipped OFDM system. With the derivations, we investigate the optimal system setting to achieve the SER lower bound in a practical OFDM system that considers both PA nonlinearity and clipping distortion. The methods and results presented in this paper can serve as a useful reference for the system-level optimization of clipped OFDM systems with nonlinear PA.