UPQ: An effective packet scheduling algorithm for delay-sensitive service in NGEO satellite network

In multihop NGEO satellite network (MSN), given the un-uniform user distribution in satellite footprints, and further affected by topology variations and link capacity jitters, the inter-satellite links (ISLs) are expected to endure wildly volatile traffic load and even suffer from severe congestion. This leads to the poor quality of service (QoS) for the delay-sensitive flows. To alleviate this problem, a novel delay-sensitive packet scheduling algorithm, referred to as Urgency-based Priority Queuing (UPQ), is proposed. It is formulated by making significant improvements in two aspects on basis of the Priority Queuing (PQ) algorithm. First, the flow scheduling priority is adjusted according to end-to-end delay performance in real-time, in purpose of ensuring timely access to bandwidth resource for the delay-urgent flows and avoiding the resource waste on the flows which have blocked on downstream links; second, the bandwidth quantity allocated to each flow is restricted according to the end-to-end delay, thus to promote the fairness of UPQ and improve the delay guarantee efficiency for multiple flows. The UPQ algorithm is evaluated via simulation against a range of traffic intensity and is compared to the typical Weighted Round Robin (WRR) algorithm and the PQ algorithm. Result suggests that the UPQ algorithm improves the delay guarantee performance in terms of reducing the delay QoS interruption rate and increasing in-time delivered packet ratio.