Research On Beidou Global Short Message Access Strategy

Short message service is one of the unique features of Beidou navigation satellite system.With the establishment of Beidou global navigation satellite system,Beidou global short message service will be widely used in various fields around the world.Within the coverage of Beidou global short message service satellites,various regions are often under multiple satellites coverage.When sending short messages,user have to face the problem of short message access.How to use a reasonable short message access scheme to improve the success rate of user access,reduce the overall system delay,and improve the utilization of satellite resources is a realistic problem that needs to be solved.The access scheme is divided into user side access and ground station side access.The quality of short message access scheme directly affects the success rate of access for users;for the system,it directly affects the overall utilization of resources and the length of delay.There is a big gap between BDS-2 regional short message service and BDS-3 global short message service in terms of system and coverage,and its access scheme cannot be directly applied.Thus,global short message service access scheme has been studied in this paper,mainly including:1)This paper proposes an improved user service access strategy based on satellite coverage service density under global non-uniform service density,which reduces the blocking rate of user service access and improves the utilization of satellite resources;2)Researched the problems in the satellite framing transmission architecture after user services access satellites.Through calculation and simulation analysis,several reasonable framing rules and framing intervals are proposed;3)Analyze the problems existing in the existing outbound access scheme,and propose an algorithm that can improve performance at a lower computational cost.Aiming at optimizing the time delay and balancing the load on the satellite,a variety of schemes for selecting satellite to be injected and user's destination satellite are proposed,and compared and analyzed through simulation.In the specific research,this paper first elaborated the working system,working process,business system and signal frame format of the Beidou global short message,which laid a theoretical foundation for subsequent access analysis and simulation parameter settings.After that,the model of global non-uniform traffic and user message length is established,the ideal theoretical system capacity of Beidou global short message was analyzed,and the shortcomings in the existing access schemes are pointed out.According to the characteristics of the global non-uniform traffic model,a short message service access scheme based on the satellite service coverage density index is proposed.According to the delay characteristics of Beidou's access service,the simulation compares the system performance of the satellite at various framing intervals and proposes several reasonable framing rules.In the outbound access part,according to the outbound system of global short messages,several factors affecting the performance of the outbound system are analyzed,and it is pointed out that the satellite selection needs to be carried out from the outbound service user destination satellites and the outbound service uplink injection satellites.In order to improve the performance of the system and according to its characteristics,several outbound schemes are proposed and compared in the two aspects of satellite selection.Through simulation analysis,two outbound schemes applicable to different outbound user traffic are pointed out.