Overlay Coded Multicast for Edge Caching in 5G-Satellite Integrated Networks

Edge caching in 5G networks shortens latency and alleviates the backhaul. Bringing content from the core network to the caches is a critical issue. When the satellite is integrated with the terrestrial 5G system, an overlay can be formed for cost-efficient content delivery. Multicast delivery over satellite is a promising scheme due to the broadcast nature of the wireless medium and wide coverage. Requests for popular content at nearby times can be aggregated through a multicast stream for bandwidth efficiency. However, directly multicast to a large audience from the satellite suffers from the problems led by fading channels and the flat topologies. The overlay architecture provides new solutions to handle the drawbacks of satellite multicast, e.g., channel and reception diversity, the difficulty of loss recovery and feedback explosion. We explicitly introduce the overlay architecture based on the configuration of multiple multicast groups and the merging of base station clusters for each communication session. The operation of this overlay is further explained. Besides, we also apply network coding to the multicast and cache networks to improve data recovery and bandwidth efficiency. Both theoretical analysis and numerical experiments demonstrate the optimization of network performance.