Online Network Slicing for Real Time Applications in Large-scale Satellite Networks

In this work, we investigate resource allocation strategy for real time communication (RTC) over satellite networks with virtual network functions. Enhanced by inter-satellite links (ISLs), in-orbit computing and network virtualization technologies, large-scale satellite networks promise global coverage at low-latency and high-bandwidth for RTC applications with diversified functions. However, realizing RTC with specific function requirements using intermittent ISLs, requires efficient routing methods with fast response times. We identify that such a routing problem over time-varying graph can be formulated as an integer linear programming problem. The branch and bound method incurs O(vertical bar L-tau vertical bar center dot (3 vertical bar V-tau vertical bar + vertical bar L-tau vertical bar)(vertical bar L tau vertical bar)) time complexity, where vertical bar V-tau vertical bar is the number of nodes, and vertical bar L-tau vertical bar is the number of links during time interval tau. By adopting a k-shortest path-based algorithm, the theoretical worst case complexity becomes O(vertical bar V-tau vertical bar! center dot vertical bar V tau vertical bar(3)). Although it runs fast in most cases, its solution can be sub-optimal and may not be found, resulting in compromised acceptance ratio in practice. To overcome this, we further design a graph-based algorithm by exploiting the special structure of the solution space, which can obtain the optimal solution in polynomial time with a computational complexity of O(3 vertical bar L-tau vertical bar + (2 log vertical bar V-tau vertical bar + 1)vertical bar V-tau vertical bar). Simulations conducted on starlink constellation with thousands of satellites corroborate the effectiveness of the proposed algorithm.