Study On Positioning Performance And Receiver Autonomous Integrity Monitoring Technology Of Multi-Constellation GNSS

Accuracy and integrity are the most important service performace of satellite navigation system.With the networking of four Global Navigation Satellite Systems(GNSSs),the combination of multi-constellation applications has become an inevitable trend.It is necessary to research on positioning performance and integrity of multi-constellation GNSS.At present,GPS and GLONASS have been put into operation for global service,Galileo system is also in construction.By the end of 2012,China had also officially announced to run BDS for regional service of Asia-Pacific,and BDS is expected to complete the construction for global service in 2020.By analyzing positioning performances of BDS for regional service,BDS for global service and their combination with GPS,GLONASS and Galileo system,integrating the advantages of these systems can not only improve the service performance of China's Beidou regional service system to the user terminal,but also make users in different environment to choose suitable navigation systems in order to provide optimal performance,and it can also provide the reference for future construction and development of BDS.The integrity monitoring of user level that the Receiver Autonomous Integrity Monitoring(RAIM)is an effective integrity monitoring method,RAIM can rapidly response to satellite faults and aerial anomalies,completely independent,without outside intervention,and can provide users with the alarm information promptly and effectively,the RAIM method for the multi-constellation fusion application must be of great value in research and application.This paper firstly summarizes referenced coordinate system and time benchmark which are adopted by four major GNSSs,and studies the transformation between the coordinate systems of the same referenced ellipsoid and the transformation of the coordinate systems between different referenced ellipsoids.Bursa seven parameters transformation model is used to achieve the unity between different systems of coordinates datum.This paper also develops the corresponding coordinate transformation software.By analyzing the transformation relationship between GNSS time and the UTC,the unity of time base between different systems is realized through correcting the integral part of difference in seconds and the fraction part of difference in seconds of the time system.Secondly,the paper gives a summary of the GNSS constellation configurations and operating conditions,and derives the discrimination method of ground coverage and space coverage of multi-constellation GNSS based on the restriction of the satellite signal beam angle and the influence of the receiver's mask angle.This paper also analyzes the ground coverage and space coverage of Beidou regional service system,Beidou global navigation system and their combination with of other GNSSs.The research results can provide reference for the application of ground and space users in multi-constellation GNSS.Thirdly,this paper studies the positioning theory of multi-constellation GNSS,analyses the positioning performance of multi-constellation GNSS and the availability and continuity of PDOP as well.Then designs a simulation analysis method of GNSS positioning performance within shielding condition,analyzes the positioning performance of multi-constellation GNSS under different shielding conditions,which can provide application guidance for users of special environment,such as mountainous area and urban canyon.A fast satellite selection algorithm based on geometry and GDOP contribution is also proposed,which greatly improves the computing efficiency,and balances the relationship between the positioning performance and the number of visible satellites.A multi-constellation GNSS positioning performance analysis system is constructed,which provides software support for multi-constellation GNSS positioning performance analysis.Finally,this paper analyzes the multi-constellation GNSS receiver autonomous integrity monitoring method,studies the probability of satellite failure with the increase of constellations,and the single satellite fault RAIM method based on multi-constellation and the RAIM method of double satellite faults based on multi-constellation.A RAIM method based on M-estimation for single fault is proposed,which improves the fault detection rate and fault identification rate by using the least square method.And the paper derives the calculation method of RAIM availability and continuity,and makes the simulation analysis of the Beidou regional service system and the future Beidou global service system,which provides some useful conclusions for the integrity monitoring of BDS.