Key points are not available for this paper at this time.
Large-scale low Earth orbit (LEO) optical satellite networks (OSNs) are expected to support increasing volumes of confidential services. Although optical inter-satellite links (OISLs) feature strong directionality and anti-interference capability, their open free-space transmission and highly dynamic topology still create non-uniform eavesdropping exposure across relay regions. Although strong physical-layer or cryptographic protection can enhance the confidentiality of optical transmission, the exposure of optical information in open free-space still poses a serious threat because intercepted optical signals may create opportunities for subsequent exploitation. Traditional survivability mechanisms, such as 1+1, and 1:1 protection, can provide a certain degree of exposure avoidance through backup routing. However, in highly dynamic OSNs, this solution is only effective within limited topology conditions and also consumes more computation resources due to the redundant links. To address this issue, this paper introduces extended OISLs (ELs) and proposes an energy-efficient survivable routing (EESR) scheme for adaptive eavesdropping exposure avoidance. First, we present the network model that incorporates both NLs and ELs. According to a time-zone-aware traffic model reflecting real-world global communication patterns, an energy-efficient eavesdropping exposure model based on fuzzy comprehensive evaluation is proposed to quantify the exposure levels of relay satellites (RSs) across four dimensions: spatial, time, technique, and environment factors. Based on the exposure assessment, the survivable routing problem is modeled as minimizing the cumulative eavesdropping exposure along relay paths. Our proposed EESR algorithm employs exposure-weighted path selection and on-demand EL activation to avoid high-exposure satellites while maintaining routing efficiency. Extensive experiments conducted on the Iridium constellation demonstrate that the EESR algorithm significantly reduces the blocking ratio by about 18.13% and the network energy consumption by about 9.11% but increases about 1.16 routing hops and decreases 15.91% link utilization. Under strict exposure constraints, the proposed scheme achieves a low path exposure level for confidential services.
Lin et al. (Tue,) studied this question.