Performance Evaluation of LEO to HAP Communication Under Wobbling, Pointing Error, and Hardware Impairments

Yerulan Zikibayev, Behrouz Maham, Refik Çağlar Kızılırmak, Hossein Safi, Dimitrios Zorbas

IEEE Open Journal of the Communications Society, 2026

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DOI 10.1109/ojcoms.2026.3664668
Data confidence 85 high
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Abstract

This study assesses the performance of communication links between low Earth orbit (LEO) satellites and high-altitude platforms (HAPs), which are critical for emerging global communication infrastructures. These links are inherently susceptible to various propagation and system-level impairments that degrade their overall effectiveness. We quantitatively investigate the impact of these impairments on link performance, focusing on two critical communication metrics: delay-outage probability and ergodic capacity. Our comprehensive modeling incorporates essential factors such as LEO satellite visibility, accounting for geometric constraints and elevation masks, and integrates the effects of transmit and receive hardware impairments (HWI), beamforming, wobbling dynamics, and pointing errors, Doppler shift alongside precisely characterized LEO orbital parameters, and integration of multiple LEO satellites’ availability over the HAP. Closed-form analytical expressions for delay outage probability and ergodic capacity have been derived for both cache-assisted and cache-free relaying scenarios under the combined influence of hardware impairments, pointing errors, and wobbling. These analytical models are further validated and complemented by a rigorous Monte Carlo simulation methodology. Using the developed system model, we simulated the combined effects of the considered impairments across three carrier-frequency scenarios. The results demonstrate how varying the number of available satellites influences overall link performance and which impairments are more sensitive to increased satellite diversity. Not all impairments respond similarly to changes in satellite availability. For example, pointing error can be partially mitigated through multi-satellite connectivity, as greater spatial diversity reduces the likelihood of severe misalignment. In contrast, hardware impairments show significantly less improvement under increased satellite availability, since distortion noise remains inherent to the transceiver hardware and affects all links uniformly.