Link Planning Schemes for Uninterrupted Inter-layer Communication in Dual-layer LEO Optical Satellite Networks

LEO optical satellite networks are attracting more and more attention from academic and industry. However, most existing studies focus on single-layer LEO constellation, which has the problems such as limited space resources and network traffic congestion. With the development of optical satellite networks, dual-layer LEO optical satellite networks can become a feasible topological structure. In this paper, we design an inter-layer links (ILLs) planning model for uninterrupted inter-layer communication (UILC) in the dual-layer LEO constellation. Based on this model, we propose two link planning schemes (i.e., the link switching (LS-UILC) scheme and the permanent link (PL-UILC) scheme) to achieve uninterrupted inter-layer communication. Then, we simulate these two schemes by setting different inter-layer laser communication distances. Numeric results show that the LS-UILC when the laser communication distance is 1292-7588km and the PL-UILC when the distance is 5060-7588km respectively achieve uninterrupted inter-layer communication. At the maximum distance of 7588km, LS-UILC can obtain a maximum of 98 valid ILLs and PL-UILC can implement a maximum of 11 permanent ILLs.