Research On Strategy Of Handover In Hybrid Satellite-Terrestrial Networks

Satellite communication system can implement communication of a global coverage, while densely populated areas on land are within the coverage area of the terrestrial wireless communication system. Therefore, the satellite communication system can acts as an extension of terrestrial wireless communications system to realize the advantages and disadvantages of two systems complementation. This is an important research direction of future wireless communication systems. Due to the extremely limited satellite resources and longtime taken by its acquisition process, so in hybrid satellite-terrestrial networks, handover delay and interruption of handover call are two issues that need to be addressed in the implementation process.In this paper, the delay performance and interruption of call have been studied and analyzed at the stages of handover decision and handover implementation. In the handover decision stage, through researching on an802.21-based scheme to optimize handover and resource management in hybrid satellite-terrestrial networks, a kind of soft-handover strategy that bases on the signal strength of link in hybrid satellite-terrestrial networks is proposed in this paper. This strategy that uses the received signal power of terminal as the judgment uses media independent handover primitive to assist the handover process. The process includes three stages:the allocation of resources, building new connection and breaking the original connection. The simulation results show that when the estimated speed is set to38m/s, in case the handover delay is formed, the actual speed of hard-handover strategy is less than45m/s, while the actual speed of soft-handover strategy that this paper proposes can reach85m/s or more. In the handover implementation stage, according to the priority of the call type and service type, a dual-threshold and dual-queue combining handover call access strategy is proposed in this paper. This strategy based on the previous handover strategies, reserves one-tenth of channels and establishes the waiting queue for handover call. The simulation results show that when the traffic intensity is8, compared with the dual-threshold-free buffer queue strategy, the handover call access strategy that this paper proposes can decrease about1‰for system grade of voice/video services, and decrease about4.5%o for system grade of data service.