Doppler frequency offset estimation and compensation in OFDM aeronautical communication systems in the presence of narrow-band interference

Abstract

A two-path model, where each path includes a linear Doppler frequency offset, is commonly applied for modeling aeronautical channels under an en-route scenario. In this study, a maximum-likelihood (ML) channel estimation-based channel response differential correlation method is used to estimate a bilinear Doppler frequency offset. Specifically, reference symbols and ML estimation are used to obtain the channel response and to separate the two paths. Then, for each path, the ML frequency offset estimation is performed via a differential correlation operation. In the absence of interference, ordinary least square (LS) channel estimation and ML channel estimation demonstrate similar performance in frequency offset estimation, but the accuracy of LS channel estimation decreases dramatically in the presence of narrow-band interference, whereas ML channel estimation continues to demonstrate good accuracy, even under strong narrow-band interference, indicating high robustness. We also present a frequency offset compensation method for a two-path channel based on obtaining a maximum signal to interference ratio. The performance of the proposed methods for frequency offset estimation and compensation are validated via simulation.