A predictive call admission control scheme for low Earth orbit satellite networks

In many previous low Earth orbit (LEO) satellite networks, intersatellite links (ISLs) are used to enhance the capability of the networks. The ISLs are continuously deleted and established since the visibility between satellites changes over time. These topological changes require rerouting of the traffic on ISLs, which unavoidably involves dropping of some ongoing calls. In general, such an ongoing call dropping degrades the quality-of-service (QoS) more severely than an initiated call blocking. We propose a call admission control scheme that allows a flexible tradeoff between dropped ongoing calls and blocked initiated calls. The call admission control scheme makes use of two techniques: traffic recasting and traffic projection. The traffic recasting maps the current traffic onto the network after the topological change whereas the traffic projection projects the recast traffic from the current time to the time of the topological change. The projected traffic is used to estimate the increase in ongoing call dropping whose QoS penalty is compared against that of increased newly initiated call blacking to make the call admission decision. Simulation results show that the proposed call admission control scheme significantly reduces the ongoing call dropping probability with only a marginal increase in the initiated call blocking and call completion probabilities.