Studies of QoS for Multipath Routing in Integrated Next Generation Satellite-Terrestrial Networks.

This thesis presents a novel forwarding scheduling algorithm to support quality of service (QoS) for multiservice applications over integrated satellite and terrestrial networks using admission control system with multipath selection capabilities. The algorithm exploits the multipath routing paradigm over LEO and GEO satellites constellation in order to achieve optimum end-to-end QoS of the client-server Internet architecture for HTTP web service, file transfer, video streaming and VoIP applications. The proposed multipath routing over the satellite networks advocates load balancing technique based on optimum time-bandwidth sharing and IP packet scheduling in order to accommodate the burst of application traffics. The method tries to balance the bandwidth load and queue length on each link over satellite in order to fulfil the optimum QoS level for each traffic type. Each connection of a traffic type will be routed over a link with the least bandwidth load and queue length at current time in order to avoid congestion state. The multipath routing scheduling decision is based on per connection granularity so that packet reordering at the receiver side could be avoided. The admission control system also adopts the Differentiated Services (Diffserv) queuing management in the terrestrial network to regulate and differentiate the traffic flows before crossing over the satellites. In addition, this thesis proposed a simple priority queue with selective packet drop function as the satellite on-board processing unit (OBP). These are done in order to relieve the satellite workload on data processing. The proposed admission control system has been tested in simulation using NS-2 software. We model the simulation scenario using multiservice application traffics with multiple connections, different file sizes and bit-error-rate (BER) variations. The performance evaluation has been carried out in term of IP packet delay, loss ratio and throughput