Cooperative Caching Strategy Based on Two-Layer Caching Model for Remote Sensing Satellite Networks

In Information Centric Networking (ICN) where content is the object of exchange, in-network caching is a unique functional feature with the ability to handle data storage and distribution in remote sensing satellite networks. Setting up cache space at any node enables users to access data nearby, thus relieving the processing pressure on the servers. However, the existing caching strategies still suffer from the lack of global planning of cache contents and low utilization of cache resources due to the lack of fine-grained division of cache contents. To address the issues mentioned, a cooperative caching strategy (CSTL) for remote sensing satellite networks based on a two-layer caching model is proposed. The two-layer caching model is constructed by setting up separate cache spaces in the satellite network and the ground station. Probabilistic caching of popular contents in the region at the ground station to reduce the access delay of users. A content classification method based on hierarchical division is proposed in the satellite network, and differential probabilistic caching is employed for different levels of content. The cached content is also dynamically adjusted by analyzing the subsequent changes in the popularity of the cached content. In the two-layer caching model, ground stations and satellite networks collaboratively cache to achieve global planning of cache contents, rationalize the utilization of cache resources, and reduce the propagation delay of remote sensing data. Simulation results show that the CSTL strategy not only has a high cache hit ratio compared with other caching strategies but also effectively reduces user request delay and server load, which satisfies the timeliness requirement of remote sensing data transmission.