Frequency Syntonization Based on PDOA Protocol in Multi-Band Systems

In this letter, we introduce a novel carrier-phase-based frequency syntonization method for multi-band systems. Different from other methods, by leveraging the wide bandwidth characteristics of multi-band signals, our approach shows superior clock-skew estimation performance compared to single-band signals. We proposed a bidirectional communication protocol to collect multi-band phase difference of arrival (PDOA) measurements. Then, we derive an approximate maximum-likelihood estimator for clock-skew estimation. Finally, link-level simulations demonstrate that the proposed method's estimation results closely approach the Cramér-Rao bound (CRB) for high signal-to-noise ratio (SNR), validating the effectiveness of our estimator. The comparison with other methods further highlights the superiority of our algorithm.