SDN-Enabled Multi-Edge Access and Cache Strategy in Satellite Terrestrial Integrated Networks

With the rapid development of satellite on-board processing, caching capability, and the inter-satellites link (ISL) transmission capacity, the 6th generation mobile networks (6G) has been expected to provide global coverage for the consumer electronics. In this paper, for the purpose of content caching and delivery to the consumer user equipment (UE), an end-to-end satellite-terrestrial integrated network with the multi-edge access and cache strategy is proposed, under the split of the control-plane (C-plane) and the user-plane (U-plane) with the software-defined features. Assuming the popularity of the contents follow the typical Zipf distribution, with three main cases are categorized and compared. In addition, the analytical expressions of service coverage probability and network service throughput are derived and analyzed, as the functions of key parameters, including the next Generation Node B (gNB) density, cache ability, access radius and Quality-of-Service (QoS) threshold. Numerical results show that the collaboration between the distributed unit (DU) and centralized unit (CU) with the joint access and caching strategy in the proposed system can significantly improve the service coverage probability and overall throughput of the network. Trade-offs between both the gNB density and the access radius with the key network performances are illustrated.