Doppler-Resilient Link Adaptation for 3D Dual-Mobility Air-to-Vehicle Open RAN Networks

Low-altitude unmanned aerial vehicles (UAVs) serving as aerial base stations for ground vehicles create air-to-vehicle (A2V) links in which both endpoints move, compressing the channel coherence time so that the reported channel quality indicator (CQI) is already stale when applied. Link adaptation calibrated for terrestrial deployments does not account for this dual-mobility aging, and the resulting overestimation of link quality inflates first-transmission errors. This paper proposes a Doppler-aware CQI correction for three-dimensional (3D) A2V Open RAN networks: an offline-calibrated back-off, indexed by the maximum Doppler frequency and the Rician K-factor, is subtracted from the measured signal-to-interference-plus-noise ratio (SINR) before CQI quantization. Because the back-off depends only on parameters the network already derives from geometry and mobility, the correction acts from the first transmission and requires no feedback convergence, unlike outer-loop link adaptation (OLLA). The scheme is implemented in Simu5G within a 3D network model providing aerial cells, dual-mobility fading decorrelation, and an Open Radio Access Network (O-RAN)-based measurement plane, and evaluated across a factorial campaign spanning three schedulers, two deployment topologies, and paired random seeds. Applying the correction to A2V links alone reduces the first-transmission error rate of aerial-served vehicles by 46-54% in an urban grid with no penalty to terrestrial links; applied network-wide, it reduces total network error by 57-62% (urban) and 54-58% (highway) and mean latency by up to 0.38 ms, at a cost of 7.3-8.8 percentage points in resource-block utilization and negligible throughput loss. Against OLLA under identical conditions, it matches or improves the error rate in the urban grid with 2.7-3.8 percentage points less overhead and reduces highway error by a further 1.2-1.3 percentage points.