精密单点定位(PPP)技术经过近二十年的发展已经取得了很大进展，但PPP位置解仍然需要约半个小时的收敛时间才能获得厘米级的定位精度，严重限制了该技术进一步的推广应用。GNSS多系统组合由于其在定位精度、可靠性、可用性上的优势，已成为GNSS技术的一种发展趋势。本项目提出引入外部电离层信息的思路，建立多模GNSS融合PPP快速收敛的理论模型和方法。具体地，研究基于非差定位技术的参考站电离层信息精确提取方法，构建电离层总电子含量的最小二乘配置空间回归模型，为用户站提供精确的电离层信息；研究融入外部电离层信息的多模PPP模型，提升位置解的收敛速度；研究位置精度因子可控的卫星优选算法，克服多模PPP中卫星数量大幅增加带来计算负担过大的问题，实现多模PPP快速解算。项目组已有很好的前期研究基础，有望获得创新性成果，为PPP技术推广应用奠定重要的理论和应用基础。

Although great progresses have been made for the precise point positioning (PPP) technology in the past approximate twenty years, it requires about half an hour to reach cm-level positioning accuracy, which seriously restricts its further applications. Multi-GNSS combination has become a development trend due to its advantages in positioning accuracy, reliability and availability. This project proposes to utilize the external ionospheric information to speed up the PPP convergence. The theoretic model and method of rapid convergence for multi-GNSS PPP is established. Specifically, the approach of obtaining precise ionospheric information at reference stations based on un-differenced positioning technique is investigated. The regional TEC (Total Electron Content) spatial regression model based on least square collocation is then established to provide precise ionospheric TEC information for users’ stations. The multi-GNSS PPP model with inclusion of external ionospheric information is studied to improve the convergence speed of position solutions. In order to implement the rapid resolution, an optimal satellite selection algorithm based on controllable PDOP is developed to overcome the issue of heavy computation burden caused by the largely increased amount of satellites in multi-GNSS PPP processing. The project team members have good research foundation and great potential to achieve innovative research results, which will lay an important theoretical and applied foundation for expanding PPP applications.