Network Slicing for Time-Varying Software Defined Integrated Space-Terrestrial Networks

Software-Defined Integrated Space-Terrestrial Networks (SD-ISTNs) offer a flexible and scalable architecture for 6G, enabling seamless global connectivity and support for diverse services. Network slicing is a critical technology in SD-ISTNs, enabling the creation of customized network slices on shared physical infrastructure to support diverse service requirements. However, network slicing in SD-ISTNs faces significant challenges due to time-varying topologies, limited and dynamic multi-dimensional heterogeneous resources, as well as diverse Quality of Service (QoS) requirements. To address these challenges, this article investigates network slicing across multiple consecutive timeslots in time-varying SD-ISTNs. We discuss key enabling technologies, including time-varying graph modeling, Virtual Network Functions (VNFs) deployment, flow routing, and their joint optimization. Specifically, we adopt time-varying graph models to characterize the dynamic topology and establish a unified representation of multi-dimensional resources in SD-ISTNs. Based on these models, we propose network slicing strategies across multiple timeslots to improve resource utilization and network performance. A case study demonstrates the effectiveness of our proposed strategy. Finally, we discuss open research issues for network slicing in time-varying SD-ISTNs.