Integration of LoS MIMO RF and Optical Links via HAPS for High-Capacity Satellite Feeder Links

This paper explores the integration of line-of-sight (LoS) multiple-input multiple-output (MIMO) RF and optical wireless links to establish high-capacity satellite feeder links via a High-Altitude Platform Station (HAPS). Our approach connects the ground station to the HAPS using a LoS MIMO RF link and to the satellite via an optical link, addressing challenges such as atmospheric effects, antenna spacing constraints, and capacity imbalances. We identify the minimum antenna spacing required at both the ground station and HAPS to maximize the LoS MIMO RF link capacity, considering various configurations and frequency bands. Additionally, we analyze the impact of HAPS movement, demonstrating that certain antenna configurations can sustain maximum capacity even when the HAPS moves along a circular path above the ground station.