Research On Uwb Ranging And Positioning Key Problems Based On Complex Channels

The demand for centimeter-level high-precision positioning is rapidly emerging in the field of automatic driving and intelligent terminals.As the commercialization of automatic driving would firstly be realized in urban freeway and underground parking lot,where the satellite signal is week or lost,ultra-wideband(UWB)positioning system makes up for the insufficient signal coverage of GNSS positioning system.Joint positioning technology of UWB positioning and GNSS positioning cover the whole positioning scene,which gradually attracts attention from the field of vehicle industry and automatic driving.With the positioning environment becoming more complex,it is necessary to explore the key problems.In UWB ranging,this thesis designs a varying pulse repetition frequency(PRF)PHY frame and ranging algorithm to confront strong multipath which reflected by long distance.In base station networking,this thesis proposes a flexible wireless synchronization method based on physical layer of IEEE802.15.4z.In terminal positioning algorithm,this thesis improves a positioning algorithm based on maximum a posteriori(MAP)estimation and regularized constraint which is adaptive to complex geometry of base stations.All of them are verified by hardware system and achieve design objectives.Firstly,in the one-to-one ranging by UWB base stations,a PHY frame is proposed to confront strong multipath which reflected by long distance to avoid untrusted results.Field tests have shown that existing UWB kits are all impacted and disturbed by this kind of multipath,so that the first path discrimination is confused and unreliable ranging results are obtained.The varying PRF algorithm could eliminate the influence of the cumulative multipath and solve the problem of ranging ambiguity.It confirms the ranging accuracy of UWB kits in a positioning system and lays a good foundation in highprecision positioning networking.Secondly,in order to make time synchronize in networking among multiple base stations,a wireless synchronization method based on physical layer of IEEE 802.15.4z is proposed in this thesis.When wireless communication among UWB base stations takes place,clock watching and positioning messages broadcasting are fulfilled in the process.To be more specific,if a UWB positioning terminal gathers the message,it could accomplish high-precision positioning computation of TDo A by post-processing.With the advantage of saving signaling resources,it could also ensure high refresh positioning rate of unlimited terminals.There is no need to build wired communication links like ethernet in the networking scheme.It only needs to supply power to each station and keep intervisible between neighboring stations,which is convenient for UWB positioning system deployed in variable scenes with low-cost and high efficiency.Lastly,in order to improve positioning performance in complex three-dimensional environment,a positioning algorithm based on maximum a posteriori(MAP)estimation is proposed in this thesis,which could completely collect and utilize the statistical characteristics of a priori information in the positioning environment.Compared with traditional algorithm,the advanced one could achieve Cram?er-Rao low bound even in ill-conditioned GDOP of base stations,with good astringency.Its average number of iterations is less than 10,with positioning precision less than 15 cm.It is a key algorithm to ensure flexible arrangement of base stations and robust positioning performance in overground-underground parking lot and stereo parking lot positioning scenes.