北斗特色服务及性能分析

Featured services and performance of BDS-3

北斗全球卫星导航系统(BDS-3)是我国独立建设、自主运行的卫星导航系统.BDS-3从星座构型、信号体制,到星上载荷都进行了创新设计,可以提供多种特色服务.自2020年7月31日正式开通服务以来,BDS-3的服务性能成为关注的热点.本文重点介绍了BDS-3提供的基于GEO星座的区域特色服务和基于MEO星座的全球特色服务.前者包括区域短报文服务(RSMCS)、BDS星基增强服务(BDSBAS)、基于B2b频点的精密单点定位服务(B2b-PPP);后者包括全球短报文服务(GSMCS)和基于MEO的搜救(MEOSAR)服务.对这些基本性能进行了评估,结果表明在星间链路(ISL)的支持下,北斗系统特色服务性能提升显著,各类服务的性能均在不同程度上优于服务性能指标要求.

BeiDou Global Navigation Satellite System(BDS-3)not only performs the normal positioning,navigation and timing(PNT)functions,but also provides featured services,which are divided into geostationary orbit(GEO)and medium earth orbit(MEO)satellite-based featured services in this paper.The former refers to regional services consisting of the regional short message communication service(RSMCS),the radio determination satellite service(RDSS),the BDS satellite-based augmented service(BDSBAS)and the satellite-based precise point positioning service via B2b signal(B2b-PPP).The latter refers to global services consisting of the global short message communication service(GSMCS)and the MEO satellite-based search and rescue(MEOSAR)service.The focus of this paper is to describe these featured services and evaluate their performances.The results show that the inter-satellite link(ISL)contributes a lot to the accuracy improvement of orbit determination and time synchronization for the whole constellation.Compared with some other final products,the root mean squares(RMS)of the BDS-3 precise orbits and broadcast clock are 25.1 cm and 2.01 ns,respectively.The positioning accuracy of single frequency is better than 6 m,and that of the generalized RDSS is usually better than 12 m.For featured services,the success rates of RSMCS and GSMCS are better than 99.9% and 95.6%,respectively;the positioning accuracies of single and dual frequency BDSBAS are better than 3 and 2 m,respectively;the positioning accuracy of B2b-PPP is better than 0.6 m,and the convergence time is usually smaller than 30 min;the single station test shows that the success rate of MEOSAR is better than 99%.Due to the ISL realization in the BDS-3 constellation,the performance and capacities of the global featured services are improved significantly.