| （英） |
Unlike fixed ground sensor terminals (GSTs), aircraft terminals change orientation due to the aircraft's movement, which subject to continual changes in orientation and position. This mobility leads to transmission window which is not only shorter, but also highly variable in both duration and timing when compared to the ground terminals, which can maintain near-constant beam alignment for longer times. Moreover, the relative velocity between the satellite and aircraft especially in Low Earth Orbit (LEO) introduces significant Doppler shifts that complicate carrier frequency tracking and increase the susceptibility to the link errors. Doppler shifts can reach to more than 22 kHz in LEO satellite link transmission and necessitate robust compensation and frequent adaptive scheduling, particularly at high elevation angles where the link budget is most favorable and the channel is least obstructed. Even though the high-elevation windows are optimal for maximum throughput and minimal path loss, it is tend to be brief due to the natural movement of the satellite in LEO at 400 km altitude, exacerbating the importance of precise, elevation-aware scheduling mechanisms. For aircraft-based networks, scheduling transmission segments at high elevation angles (higher than 40$^circ$) is crucial, not only focuses the limited airtime on periods when link quality is the highest, but it also reduces total airtime requirements while maintaining or even improving reliability and data rates. This strategy capitalizes on the stable geometry and reduced atmospheric attenuation at higher elevations, effectively mitigating transmission errors introduced by Doppler and link margin variations. This paper proposes the segment scheduling where the elevation is higher than 40$^circ$, which reduces the transmission airtime, yet improves the quality of the transmission. The findings highlight that elevation-aware scheduling significantly enhances the performance of LoRa-satellite communication from aircraft-based terminals. By prioritizing high-elevation transmission windows, the approach effectively mitigates the challenges posed by Doppler shifts and link variability, leading to improved reliability and efficiency in data transmission. |