A predictive QoS routing scheme for broadband low Earth orbit satellite networks

Abstract

Low Earth orbit satellite networks can augment terrestrial wireless networks to provide global broadband services to users regardless of the users' locations. Delivering QoS guarantees to the users of LEO satellite networks is complicated since the footprints of the LEO satellites move as the satellites traverse their orbits, and thus, causing frequent user handovers between the satellites. Traffic on inter-satellite links of a particular satellite change as the user traffic served by the satellite changes with the satellite's mobility. The change in user traffic on the inter-satellite links may cause violation of QoS requirements of on-going calls. We propose a novel routing algorithm called the predictive routing protocol (PRP), that exploits the predictive nature of the LEO satellite topology to maximize the total number of users served by the system, while maintaining each user's QoS requirements. The PRP predicts the user traffic load on the inter-satellite links up to a short time in the future by using the deterministic knowledge of the LEO satellite topology, and user location information. The PRP determines multiple paths for a particular connection that effectively help avoid possible future bottlenecks as predicted by estimated future traffic on the inter-satellite links. The algorithm is compared with other non-predictive routing protocols such as IP routing by extensive simulations and it is shown that PRP can deliver deterministic QoS guarantees (such as delay jitter), without over-reserving channel bandwidth. An admission control curve has also been obtained which may be used to ensure that the desired QoS metrics may be guaranteed.