An RF/FSO Hybrid Routing for Satellite Constellation Systems

Earth observation satellites obtain various data from the Earth and its surrounding environment. The amount of data handled by Earth observation satellites has increased in step with the improved performance of observation equipment. By using free-space optics (FSO) for satellite communication, much faster data transmission becomes possible. However, FSO is influenced by atmospheric conditions, which can disrupt the optical link between a satellite and ground station (GS). In contrast, a radio-frequency (RF) link is hardly ever influenced by atmospheric conditions, and communication can continue even when clouds pass between the satellite and GS. In this paper, we propose RF/FSO hybrid routing for satellite constellations. In the proposed method, when the FSO link between a satellite and GS is disrupted due to atmospheric phenomena, a detour path through other satellites with a functioning FSO link to the GS is established to increase the total amount of data transmitted to the GS. Using numerical calculations, we show that the proposed method is effective for increasing the total amount of data transmitted from a satellite to its GS compared to the conventional method.