Low delay fragment forwarding in LEO satellite networks based on named data networking

The LEO satellite network with cache and computing capabilities has become an important evolution of the next generation (6G) mobile communication network. The satellite networks employing Named Data Networking (NDN) can achieve swift content access through in-network caches and data multicast. The data packet is the basic unit of transmission in NDN. In order to adapt to the limited MTU of links, large data packets must be transmitted in fragments. However, due to the issues such as large transmission delay, redundant reassembly, and infeasible fragment reuse, the existing fragmentation methods in NDN cannot be applied to satellite communication. In this paper, we propose a low delay fragment forwarding method in NDN: Direct Forwarding and Reuse of Fragments (DFRF). Specifically, the content in the large data packet will be split and packaged into fragments that conform to NDN semantics. Once the fragment is received by the satellite router, it can be forwarded directly without reassembly, thus saving the forwarding delay. In addition, we design a new fragment format and the list-based cache, so that all fragments generated from the same data packet can be cached intact in a list, and each fragment can be reused as a complete packet in the content store (CS). The proposed approach has been further evaluated and the simulation results show that compared with the NDN Link Protocol (NDNLP), using the DFRF method, the end-to-end transmission delay of large content is reduced by up to 51%, and the content acquisition delay is reduced by up to 60% through fragment reuse.