The core performance elements of global navigation satellite system include availability, continuity, integrity and accuracy, all of which are particularly important for the developing BeiDou global navigation satellite system (BDS-3). This paper describes the basic performance of BDS-3 and suggests some methods to improve the positioning, navigation and timing (PNT) service. The precision of the BDS-3 post-processing orbit can reach centimeter level, the average satellite clock offset uncertainty of 18 medium circular orbit satellites is 1.55 ns and the average signal-in-space ranging error is approximately 0.474 m. The future possible improvements for the BeiDou navigation system are also discussed. It is suggested to increase the orbital inclination of the inclined geostationary orbit (IGSO) satellites to improve the PNT service in the Arctic region. The IGSO satellite can perform part of the geostationary orbit (GEO) satellite’s functions to solve the southern occlusion problem of the GEO satellite service in the northern hemisphere (namely the “south wall effect”). The space-borne inertial navigation system could be used to realize continuous orbit determination during satellite maneuver. In addition, high-accuracy space-borne hydrogen clock or cesium clock can be used to maintain the time system in the autonomous navigation mode, and stability of spatial datum. Furthermore, the ionospheric delay correction model of BDS-3 for all signals should be unified to avoid user confusion and improve positioning accuracy. Finally, to overcome the vulnerability of satellite navigation system, the comprehensive and resilient PNT infrastructures are proposed for the future seamless PNT services.

中文翻译：

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北斗全球导航卫星系统的基本性能和未来发展

全球导航卫星系统的核心性能要素包括可用性，连续性，完整性和准确性，所有这些对于开发北斗全球导航卫星系统（BDS-3）都特别重要。本文介绍了BDS-3的基本性能，并提出了一些改善定位，导航和计时（PNT）服务的方法。BDS-3后处理轨道的精度可以达到厘米级，18颗中圆轨道卫星的平均卫星时钟偏移不确定度为1.55 ns，平均空间信号测距误差约为0.474 m。还讨论了北斗导航系统未来可能的改进。建议增加倾斜地球静止轨道（IGSO）卫星的轨道倾角，以改善北极地区的PNT服务。IGSO卫星可以履行对地静止轨道（GEO）卫星的部分功能，以解决北半球GEO卫星业务的南向遮挡问题（即“南墙效应”）。星载惯性导航系统可用于实现卫星机动过程中的连续轨道确定。另外，可以使用高精度的星载氢时钟或铯时钟将时间系统保持在自主导航模式下，并保持空间基准的稳定性。此外，应统一针对所有信号的BDS-3的电离层延迟校正模型，以避免用户混淆并提高定位精度。最后，