Research On Theory,Performance Assessment And Optimization Of GNSS User-based Integrity Monitoring Algorithm

Global Navigation Satellite Systems(GNSS)has played a huge role in all areas of military and civilian,and high-precision positioning performance has been able to meet the needs of most users.However,the inherent vulnerability of GNSS signals makes their pseudo-range and carrier phase observations susceptible to interference from satellites,ground control,external environment and other factors,resulting in abnormal faults.Therefore,the reliability of GNSS positioning performance,or integrity,has become an important indicator of concern in the field of life safety such as civil aviation.This paper mainly studies the theory and methods of user-based integrity monitoring,including Receiver Autonomous Integrity Monitoring(RAIM)and Advanced Receiver Autonomous Integrity Monitoring(ARAIM),and the effectiveness of the algorithm was evaluated and verified by using measured data and simulation.On this basis,some defects of RAIM algorithm and ARAIM algorithm are analyzed,optimized and improved.The main work and achievements of this paper are as follows:1.A new RAIM strategy combining carrier phase smoothing pseudo-range algorithm is proposed for small fault detection and identification.For the defect of the traditional RAIM algorithm,it is difficult to detect and identifysmall outliers.Under the premise that the cycle slip is only detected and not repaired,RAIM algorithm is used to solve the divergence problem in the initial stage of the Hatch filter.At the same time,based on the error variation in the unit weight of the positioning solution,the satellite with poor positioning performance is eliminated by the method of selecting the satellites,and the fault detection and identification are jointly performed with the RAIM algorithm.2.An Integrity Support Message(ISM)parameter differentiation hypothesis strategy is proposed to evaluate the performance of BDS(BeiDou Navigation Satellite System)ARAIM in the Asia Pacific region.For the heterogeneous features of BDS constellation,the availability and integrity of ARAIM for real stations and the Asia Pacific region are assessed by different ISM parameters assumption.Then,compare the ARAIM performance of GPS/BDS and GPS/GLONASS combination to analyze the performance and contribution of BDS in the Asia Pacific region.Finally,the improvement of the performance of the BDS constellation ARAIM by the use of the new BD-3 satellites is analyzed.3.Analyze the impact of constellation-wide fault threats on Multi-GNSS ARAIM user performance.For the dual-frequency multi-constellation(DFMC)GNSS opportunity,which user's redundant observation resources are greatly increased,the geometric strength is greatly improved,and the dual-frequency combination eliminates the ionospheric delay,the real data is used to verify the performance improvement trend of ARAIM from single constellation to multi-constellation combination.4.A satellite selection method suitable for ARAIM algorithm is proposed to optimize the subset complexity of Multi-GNSS ARAIM.For the defect of too many subsets and compute burden when Multi-GNSS combination MHSS ARAIM,a satellite selection method based ISM for ARAIM is proposed.The performance and efficiency of the method and the conventional fast satellite selection methods are compared,and the effectiveness of the proposed method is verified with real data.