A Hierarchical Routing Algorithm for Satellite Networks Considering FSO Communication

Insufficient ground stations promote the emergence of inter-satellite links (ISLs). Nowadays, adopting free space optical (FSO) ISLs has been a new trend for data communications. However, FSO ISLs across the atmosphere may perform worse in adverse weather such as fog or snow. In addition, using ordinary flat routing causes an excessive processing overhead, and diverse quality of experiences (QoEs) cannot be well satisfied. To solve these problems, we propose a Hierarchical Routing protocol for low/medium earth orbit (LEO/MEO) Satellite RF( radio frequency)/FSO Communication Networks (HR-SFCN). The entire network is divided into several LEO-satellite clusters, and each cluster treats the MEO satellite as the manager. To satisfy diverse QoE requirements, we propose the optimization algorithm for data interactions within the cluster. To reduce the processing overhead, we utilize MEO satellites as relay nodes for inter-cluster communications. To guarantee the link availability, we also perform adaptive RF/FSO link switching according to weather conditions. Given a STK(satellite tool kit)-based satellite communication network model, simulation results demonstrate that our HR-SFCN achieves a good trade-off among packet loss rate, path cost and end-to-end delay. Our RF/FSO hybrid system also increases the link availability up to 99.999%.