SAST-VNE: A Flexible Framework for Network Slicing in 6G Integrated Satellite-Terrestrial Networks

Network slicing (NS) is one of the key techniques to manage logical and functionally separated networks on a common infrastructure, in a dynamic manner. As the complexity of virtualizing a full infrastructure required unprecedented effort, the initial idea of combining satellite and terrestrial networks has not been fully implemented in 5G yet. 6G networks are expected to further bring NS to a substrate network that is more heterogeneous, due to the full integration between terrestrial and satellite networks. NS describes the process of accommodating virtual networks, typically composed of nodes and links with the respective requirements, into the main infrastructure. This is an NP-Hard problem, typically also known as Virtual Network Embedding (VNE). Existing VNE solutions are designed per use-case and lack flexibility, adaptation and traffic-awareness, especially in such dynamic satellite environment. In this work, we investigate the VNE implementation to integrated satellite-terrestrial networks and propose a novel flexible framework, named Slice-Aware VNE for Satellite-Terrestrial (SAST-VNE), which 1) operates based on traffic prioritization; 2) jointly optimizes the load-balancing and the migration cost when network congestion occurs; and 3) provides a near-optimal solution. We compare SAST-VNE to existing well-known near-optimal VNE algorithms such as VINEYard and CEVNE and the shortest-path SN-VNE solution for satellite networks. The simulations showed that SAST-VNE reduces the migration costs between 10% and 40% during satellite handovers while maintaining the network load under control. Furthermore, when congestion occurs, SAST-VNE proved to be flexible in matching the priority of the slice, i.e., tolerated latency, with the time complexity and optimality of the solution.