Online Network Slicing for Real Time Applications in Large-scale Satellite Networks
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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(|ℒ^τ| · (3 |𝒱^τ| + |ℒ^τ|)^|ℒ^τ|) time complexity, where |𝒱^τ| is the number of nodes, and |ℒ^τ| is the number of links during time interval τ. By adopting a k-shortest path-based algorithm, the theoretical worst case complexity becomes O(|𝒱^τ|! · |𝒱^τ|^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|ℒ^τ| + (2log|𝒱^τ|+1) |𝒱^τ|). Simulations conducted on starlink constellation with thousands of satellites corroborate the effectiveness of the proposed algorithm.
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