Research On Position Solving Method And Assessment Techniques Of Muti-constellation In GNSS

The number of visible satellites is gradually increasing due to the continuous development of Global Navigation Satellite System(GNSS). Compared to single constellation, multi-constellation satellite navigation system has obvious advantages in terms of visible satellites number, accuracy, integrity, availability and so on. However, the multi-GNSS constellation leads to a remarkable increasing of computation though it brings some advantages. While guaranteeing the positioning precision, it is an important problem to improve the efficiency of selection and positioning, thereby achieve better real-time performance.Aiming at improving the efficiency of the multi-GNSS constellation selection and positioning, this paper do researches on fast positioning solution, quick calculation of geometric dilution of precision(GDOP), GDOP recursive properties and some other. Main contents are as follows:(1) Proposed a direct solution for multi-GNSS constellation, and evaluated its computation load. Compared to the least squares algorithm, the proposed method needs no iterative calculation, and the results can be directly given. Additionally, the computational cost is decreased obviously while ensuring the positioning accuracy of.(2) Studied quick calculation of GDOP in multi-GNSS constellation.A fast calculation algorithm of GDOPwas proposed. Compared with the traditional calculation method, the algorithm has almost the same precision, but less computational cost, which can calculate GDOP quickly and improve the efficiency of satellite selection in multi-GNSS constellations.(3)Theoretical analysis and simulation of GDOP recursive characteristics(impact on GDOP of visible stars number) were given. The results showed that adding stars of current satellite system would lead to GDOP decreasing; but when adding stars of other constellations, GDOP value would increase.(4) Studied satellite selection problem in multi-GNSS constellation. Firstly it was verified that the satellite selection algorithm based on biggest tetrahedron volume was not suitable for multi-GNSS constellations.Then a satellite selection algorithm based on Weighted Position Dilution of Precision(WGDOP) contribution to muti-GNSS constellation is proposed.Compared to the traditional satellite selection algorithm,the algorithm has less amount of calculation and higher positioning accuracy.