Selective Handover and SLA-Aware Resource Allocation for Diverse Services in a LEO Satellite Network

Abstract

The integrated satellite-terrestrial networks (STNs) aim to provide ubiquitous connectivity and support various services with diverse requirements. Each service request has to go through a sequence of virtual network functions (VNFs) that should be mapped on its routing path. The STNs are equipped with limited communication and computation resources, making it challenging to enable heterogeneous services. Furthermore, the movement of satellites causes frequent changes in topology, which can impact the continuity of long-lasting requests. For requests lasting multiple time frames, the VNF mapping update and path recomputation at the beginning of each time frame is computationally expensive and can cause unwanted service interruptions. Therefore, we propose a selective handover strategy where the path recomputation and VNF remapping are done only if there is a change in the previous routing path. The selective handover strategy ensures that only critical handovers are carried out while discouraging unnecessary reconfigurations, which result in service discontinuity. We develop a software-defined networking (SDN) based experimental testbed that allows us to realistically consider the system constraints. The VNF mapping and path computation for a request are done in a proactive manner, and the rate meters are installed on the switches according to the current network traffic to efficiently utilize the available bandwidth. The simulation results certify that the proposed strategy reduces the packet loss by up to 11.5% and 18.5% as compared to the benchmark schemes and provides stable throughput for eMBB services with minimal service-level agreement (SLA) violations, while also ensuring the latency requirements of mMTC.