IRNSS和QZSS在各自主服务区域的L5定位性能评估：独立系统与GPS联合

印度区域导航卫星系统（IRNSS）与日本准天顶系统（QZSS）是近年来宣布正式运行的两个区域卫星导航系统。本文首先评估了IRNSS和QZSS在各自主服务区域的L5信号单点定位性能。然后，为了探究导航星座结构差异对各区域系统联合GPS在城市峡谷环境下定位性能的影响程度，详细对比分析了卫星截止高度角为5°、15°、25°、35°、45°、55°时各区域系统在其主服务区内联合GPS定位的表现。结果表明：① IRNSS在其主服务区内可提供全天连续独立L5定位服务，水平方向定位精度小于2.50m，高程方向定位精度小于4.10m；② QZSS在其主服务区内只能提供全天部分时段的独立L5定位服务，水平方向定位精度小于4.80m，高程方向定位精度小于7.40m；③由于QZSS独特的星座结构，其在主服务区城市峡谷环境中联合GPS定位的性能要优于IRNSS在其相应主服务区联合GPS定位的表现，尤其是在天空视野有限的情况下。本文结果对决策者设计新的区域导航系统具有一定的参考价值。

Assessing the L5 positioning performance of IRNSS and QZSS in their primary service areas: stand-alone and combined with GPS

The Indian Regional Navigation Satellite System (IRNSS) and Quasi-Zenith Satellite System (QZSS) are two Regional Navigation Satellite Systems (RNSSs) announced as fully operational in recent years. In this contribution, stand-alone L5 single point positioning (SPP) performances of IRNSS and QZSS are first assessed in their primary service areas. Then, the performance of each RNSS assisting GPS positioning with satellite cut-off elevation angles set at 5°, 15°, 25°, 35°, 45°, and 55° in its primary service area is compared and analyzed in detail. It is to examine to what extent the constellation configuration difference can affect the performance of each RNSS assisting GPS positioning in the urban canyon environment. The results demonstrate that:① IRNSS can provide 24-hour continuous independent L5 positioning service with a positioning accuracy of <2.50 m in horizontal, and <4.10 m in vertical in its primary service area; ② QZSS can only provide independent L5 positioning service of limited availability with a positioning accuracy of <4.80 m in horizontal, and <7.40 m in vertical in its primary service area; ③ the performance of QZSS assisting GPS positioning in the urban canyon environment in mainland Japan is better than that of IRNSS in its primary service area, especially in the situation of a limited sky view, due to its unique constellation configuration. The finding of this study could inspire the policy-makers when they are designing a new RNSS.