With the accelerated deployment of Low Earth Orbit (LEO) mega-constellations,
such as Starlink and OneWeb, satellite networks are transitioning from providing
best-effort connectivity to supporting stringent, mission-critical services,
including autonomous driving coordination, ultra-high-definition video
streaming, and real-time financial transactions. This paradigm shift imposes
highly heterogeneous Quality of Service (QoS) requirements regarding latency,
bandwidth, and reliability. However, traditional unified scheduling and static
routing mechanisms are inadequate for handling the dynamic topologies and bursty
traffic inherent in LEO environments, often leading to service starvation or
excessive packet loss. To address these challenges, this paper proposes an
integrated primary-backup path guarantee framework that tightly couples a
Multi-Level Feedback Queue (MLFQ)-based dynamic scheduling algorithm with a
Dynamic Weight Adaptive Routing Algorithm (DWARA). The MLFQ scheduler employs an
aging-based priority promotion mechanism to dynamically adjust time slices,
effectively preventing low-priority traffic starvation while ensuring ultra-low
latency for Class A services. Concurrently, DWARA models QoS as a
three-dimensional vector (Throughput, Delay, Reliability) and utilizes the
eigenvector method to derive service-aware weights for path selection. To
validate the efficacy of the proposed scheme, comprehensive simulations were
conducted using STK and Python, emulating a 64-node polar constellation under
varying fault conditions. The results demonstrate that the integrated framework
significantly outperforms baseline algorithms. Specifically, it reduces the
average blocking rate by up to 37% under scenarios with 10 faulty satellites
compared to Dijkstra, while lowering end-to-end latency for delay-sensitive
services to approximately 28 ms at a traffic arrival rate of 500. Furthermore,
the framework achieves a 92% bandwidth satisfaction rate for high-throughput
services and maintains near-zero packet loss for high-reliability transmissions,
offering a scalable and robust QoS assurance solution for next-generation
space-air-ground integrated networks.