The Research On GNSS Integrity Monitoring Theory And Assisted Performance Enhancement Technique

With theoretical researches related to satellite navigation being executed deeplyand the rapid development of Global Navigation Satellite System (GNSS). As areal-time ten parameters (Three-dimensional position, velocity, attitude andone-dimensional time) sensor, GNSS performances (Accuracy, availability, integrityand continuity) have been greatly enhanced. The applications of satellite navigationhave also been widened, which is playing a more and more role in almost every fieldof our daily life as well as military. However, because of some inherit characteristicsof GNSS, like vulnerability, uncertainty, probability of error and low power, the levelof trust to many users of GNSS services have been reduced. Without providingservice to users with good integrity performance, it could only be used as assistantnavigation method. In other words, GNSS has to overcome this to become a primarynavigation method. GNSS integrity monitoring-related research has become one ofthe hot points in the field of satellite navigation.Aiming at some weaknesses and blind spots in GNSS integrity monitoring andperformance augmentation technique, relying on the research work of the NationalHigh-tech Research and Development Program of China (863Program) with topic"GNSS Vulnerability Analysis and Research of Signal Transmission Environment".This paper fully analyzed the causes and natures of GNSS integrity, studied theapproaches and methods to solve the GNSS integrity problem. A complete three levelsGNSS integrity monitoring theory is proposed from the overall perspective, and acomprehensive assessment architecture of GNSS integrity monitoring system is built.Quality Control theory, Signal Analysis theory and Consistency Check theory havebeen utilized in this paper to complete the Global System Level ConstellationIntegrity Monitoring (GSLCIM), Local Augmentation Level Information IntegrityMonitoring (LALIIM) and Terminal Application Level User Integrity Monitoring(TALUIM). Comprehensive evaluation method of GNSS constellation level based onquality control method have been putted up, GNSS steerable Parabolic TrackingAntenna for Signal Quality Monitoring System (GPTA-SQMS) has been designed andcompleted, RANdom SAmple Consensus (RANSAC) integrity monitoring methodhas been improved. GNSS integrity monitoring performance augmentation techniqueof terminal receiver in the presence of other redundancy information and differentialprocess could be done has been studied deeply. At the same time, GNSS integritymonitoring in GNSS attitude determination (GNSS-AD) filed has also been executed. In this paper, a large number of simulation results and monitoring results have beenlisted to demonstrate the usability of this GNSS integrity monitoring system, whichcould be some kind of reference of GNSS integrity monitoring and assistantperformance enhancement. This kind of analysis method could also be utilized inservice performances monitoring of other satellite system like communication, remotesensing, meteorological, resource and detecting.This paper is constituted of three themes. The first theme is "The basic theory ofGNSS integrity", the second major theme is "The theoretical system of GNSSintegrity monitoring" and the third theme is "Assistant performance enhancements ofGNSS integrity monitoring".Four main innovations in this paper are summarized as follows:(1) The generation mechanism and content and external of GNSS integrityproblems are comprehensively analyzed. According to the location and characteristicsof the subject of integrity monitoring, a complete three levels GNSS integritymonitoring method based on corresponding theoretical analysis is proposed. And theconstruction of GNSS integrity monitoring assessment system is built. It provides areference to the research and implementation of GNSS integrity monitoring. And thisanalytic hierarchy processes and results have some reference values to the serviceperformance monitoring and enhance of other satellite system.(2) Two evaluation parameters, Minimal Availability of Integrity (MAI) andMinimal Detectable Effect Holes Ratio (MDEHR) in Global System LevelConstellation Integrity Monitoring (GSLCIM) have been putted up, one evaluationmethod in constellation integrity monitoring based on quality control has beenproposed. Conditions of GNSS constellation, observation situation, measurementnoise and application requirements have been taken into consideration. Based on alarge number of simulations, for example single and multiple constellations like BDS,GPS, QZSS and IRNSS in two dimensions of time and space of different conditionscontaining city canyon have been evaluated to test the integrity of GNSS. Thisintegrity assessment method and the simulation results have some reference values tonavigation constellation configuration and integrity prediction in practicalapplications of GNSS.(3) According to three monitoring locations of the user receiver radio frequency(RF) front-end, baseband and measurement solvers, Terminal Application Level UserIntegrity Monitoring (TALUIM) has been executed from RF environment, basebandand consistency check, improvements have been done based on RANSAC-RAIM, Asubset of the satellite-based precheck GDOP exclusion and dynamic threshold LOSvector precheck FRANSAC-RAIM methods have been presented. According to thesimulation of real flight environment, improved FRANSAC-RAIM method can notonly detect multiple errors and minor error, but also can reduce the alarm time byimproving computing efficiency, which is significant demand for RAIM integrity warning.(4) This paper improved the solving method of Attitude Dilution Of Precision(ADOP), proposed the choice satellites method based on ADOP, analyzed therelationship between the length of baseline and elevation, proposed attitude AngleAlarm Limit (AAL) in GNSS-AD integrity monitoring, converted an approximatealarm limit equation from distance domain to attitude angel domain, thereby theintegrity of the measurement method in positioning is introduced to GNSS attitudedetermination, achieve GNSS-AD integrity monitoring methods. GNSS-AD integritymonitoring method has been proposed by using more differential assistances. Twosingle difference between the adjacent time epoch (Delta SD-1S2A and DeltaSD-2S1A) were constructed in this paper to enhance the performances of detectionand remove errors caused by different sources, and ultimately achieved the propose ofDifference Assistant GNSS Integrity Monitoring (DAIM) and integrity augmentationby combining both the advantages of Delta SD-1S2A and Delta SD-2S1A.