中文摘要：

针对北斗、GPS、GLONASS和GALILEO等单星座系统定位中存在的定位精度不足、可见星不多、定位可靠性不强等问题，研究了一种利用北斗、GPS、GLONASS和GALI—LEO多星座信息在统一坐标系中采用最小二乘法进行组合导航定位的方法。仿真结果表明：北斗与GPS双系统的定位精度优于单纯的北斗系统精度，而采用北斗／GPS／GLONASS／GALILEO多星座组合导航定位能够有效提高用户的定位精度和可靠性，研究成果对北斗系统的精度验证和多星座接收机的实现具有参考意义。

英文摘要：

Beidou, GPS, GLONASS and GALILEO system has low positioning accuracy, low reliability and less visible satellites respectively. The positioning algorithm of multi-constellation integrated navigation system of Beidou/ GPS/GLONASS/GALILEO was studied in the paper. Different coordinate systems and time systems of four satellite constellations were uniformed; the least square method was used in the positioning calculation. Simulation results indicate： System based on Beidou ＆ GPS has the better performance than single Beidou system, and the Beidou/GPS/GLONASS/GALILEO multi-constellation integrated navigation system can greatly improve the positioning precision and reliability with more visible satellites. The result has reference value on realization of Beidou system and its multi-constellation receiver.