An Efficient QAM Detector via Nonlinear Post-distortion based on FDE Bank under PA Impairments

TL;DR

This paper introduces a novel receiver structure for single-carrier transmission with FDE under PA nonlinearities, employing nonlinear post-distortion techniques to significantly improve performance.

Contribution

It proposes a new two-stage receiver with symbol rate post-distortion using GPR and neural networks, addressing nonlinear interference in FDE systems under PA impairments.

Findings

GPR and NN post-distortion outperform existing methods in BER and information rate.

The proposed decision metric enhances FDE performance in nonlinear channels.

Simulation results confirm the effectiveness of the proposed techniques.

Abstract

In this paper, we propose a novel receiver structure for single-carrier transmission with frequency domain equalization (FDE) that is exposed to power amplifier (PA) nonlinearities. A two-stage approach is adopted, in which linear communication channel is equalized at the first stage, and it is followed by a post-distortion where nonlinear distortion is reduced. In literature, nonlinear processing techniques are proposed, which performs memoryless compensation of nonlinear distortion together with FDE. However, in this study, we show that even if a memoryless nonlinearity exists, the received signal is impaired by nonlinear inter-symbol-interference. Therefore, we propose a class of symbol rate post-distortion techniques, which use neighboring received symbols to suppress the nonlinear interference. Two different post-distortion techniques, Gaussian process regression (GPR) and neural network (NN) based post-distorters, are considered. Also, a decision metric, combining outputs of fractional delayed bank of FDE's after post-distortion, is proposed to overcome performance degradation of FDE for frequency selective channels under nonlinear distortion. Performances of the proposed techniques are compared with that of the state-of-the-art techniques in terms of bit error rate and achievable information rate metrics via simulations. Simulation results demonstrate that GPR and NN based post-distortion methods together with bank of FDE outperform state-of-the-art techniques.