Study On Channel Allocation Scheme In Satellite Mobile Communication System With High-speed Terminal

As an important supplement to terrestrial network, satellite network can overcome the limitations of geographical and economic factors, and achieve global seamless coverage. With the advantages of low transmission power, low transmission delay and high bandwidth utilization, low earth orbit (LEO) satellite system can provide high quality and timely mobile communication services, and it will become an important component in the future data transmission network. However,in order to achieve efficient frequency division multiplexing, the coverage area of the LEO satellite is divided into a large number of beam cells. LEO satellites rotate around the earth's surface in high speed, which will bring users frequent beam switching. Especially for the high-speed terminal, compared with the sub satellite rate, its speed can't be ignored therefore will experience more frequent beam switching. At the same time, due to the sensitivity of high-speed terminal to delay, it also has a high demand for fast access. Therefore, it is significant to study the allocation of limited channel resources in the LEO satellite mobile communication system adapting to the high-speed terminal.Firstly, this paper studies the channel assignment strategy of LEO mobile communication system adapting to high-speed terminal under single-class service condition, and proposes a time-based channel reservation algorithm with adaptive overbooking (ATCR-O). Based on the location distribution of user terminals and the flow ratio of high-speed terminals, ATCR-O strategy reserves channels with adaptive overbooking for handover calls of high-speed terminals, to avoid the decline in service quality of high-speed terminals because of unreasonable number of virtual channels. This paper makes a theoretical analysis and performance simulation of ATCR-O strategy. The simulation results show that this strategy can guarantee the high-speed terminal handover call dropping probability is close to zero while obtain lower new call blocking probability, and thus improve the service quality of the whole system.With the development of multimedia services, satellite networks have begun to provide multi-class service. This paper secondly studies the channel assignment strategy of LEO mobile communication system adapting to high-speed terminal under multi-class service conditions, and proposes an updated dynamic channel reservation strategy based on priorities (UDCRP). This strategy can provide dynamic channel reservation for multi types of calls, multi-class service and multi types of terminals. The strategy sets a reasonable priority for all kinds of users,and introduces genetic and particle swarm hybrid algorithm (GA-PSO) to solve the optimal reserved channel thresholds dynamically. This paper makes a theoretical analysis and performance simulation of UDCRP strategy. The simulation results show that the strategy can guarantee the best average quality of service for the overall system while provide satisfactory service quality for high priority users including high-speed terminals, real-time services and handover calls.