Nonlinear symbols combining for Power Amplifier-distorted OFDM signal reception

2025-06-06

AI Summary

To address severe distortion of OFDM multicarrier signals and significant performance degradation of conventional receivers caused by power amplifier (PA) nonlinearity, this paper proposes a hard-decision-free higher-order symbol combining (HOC) receiver. The method introduces machine learning into non-data-aided joint symbol coefficient optimization for the first time, fully exploiting frequency-domain diversity induced by PA distortion to enhance robustness. It overcomes the performance saturation of traditional decision-aided receivers in the low bit-error-rate (BER) regime and is compatible with forward-error-correction (FEC)-driven adaptive modulation and coding. Simulation results demonstrate that the proposed HOC receiver outperforms both standard and representative decision-aided receivers in BER performance. However, its computational complexity increases rapidly with the number of subcarriers, necessitating further optimization for wideband applications.

Technology Category

• Machine Learning: Hardware-aware ML
• Search and Optimization: Mixed Discrete/Continuous Search
• Intelligent Robots: Learning & Optimization for ROB

Application Category

• Systems and Infrastructure for Web, Mobile and WoT: Applied ML and AI for Web-based mobile applications
• Economics, Online Markets and Human Computation: Data quality aspects of human-annotated datasets
• User Modeling, Personalization and Recommendation: On-Device user modeling, personalization, and recommendation

Abstract

Nonlinear distortion of a multicarrier signal by a transmitter Power Amplifier (PA) can be a serious problem when designing new highly energy-efficient wireless systems. Although the performance of standard reception algorithms is seriously deteriorated by the nonlinear distortion, the more advanced solutions allow the utilization of additional frequency diversity caused by nonlinear PA. However, while most of the advanced receivers are decision-aided, their gains are observed mostly in a relatively low Bit Error Rate (BER) region, not targeted by adaptive Modulation Coding Schemes utilizing Forward Error Correction (FEC). In this paper, a non-decision-aided Higher-Order Combining (HOC) reception scheme is proposed. While the analytical formulas for finding symbols combining coefficients are not known, machine learning is used for deriving them. The simulation results show an improved BER performance with respect to a standard reception and one of the established decision-aided receivers. However, as HOC has computational complexity that increases rapidly with the number of subcarriers utilized, more studies are needed to apply it in a wideband system.

Problem

• Addressing nonlinear distortion in Power Amplifier-distorted OFDM signals
• Improving Bit Error Rate performance without decision-aided methods
• Reducing computational complexity for wideband system application

Innovation

• Non-decision-aided Higher-Order Combining reception
• Machine learning for symbol combining coefficients
• Improved BER performance with computational complexity