Research In Signal Synchronization Problems Of UWB Positioning System

Ultra-Wide Band is a wireless communications technology which does notemploy the carrier but the discontinuous pulse with nanoseconds duration tocommunicate. No carrier modulation and narrow pulse determine the UWBcommunications system having simple equipment, strong penetrating power, the timeresolution is strong and the advantages of anti-multipath ability, so the positioningaccuracy is very high. IEEE802.15.4a standard is the first precise positioning rangewireless standards in the physical put forward by the IEEE, which gives a completechannel model of UWB indoor positioning, nine channel instance is given.Communication protocol is also given in the standard which UWB positioning systemstandard need to follow. But there are many problems to solve, these problems willaffect the UWB indoor positioning accuracy, for example, on the study of single basestation positioning in UWB positioning, communication protocols which is suitablefor the single base station positioning, synchronization problem in UWB positioningsystem.This paper mainly aims at the design of the single base station positioningsystem, the synchronization between base station and tag and the standard extensionor redesign based for communication protocols on IEEE802.15.4a which is suitablefor the single base station positioning system. On consulting a large number ofliteratures at home and abroad, the paper designs a kind of model of UWB highprecision positioning system; gives an innovative positioning communication framestructure, particularly in the design of the synchronous head and the physical layerprotocol, and at the same time, gives the design of the timestamp message, Abi-directional clock synchronization algorithm based on linear regression is given,frame synchronization and the level of pulse synchronization for signal propagationdelay of the theoretical derivation is given. The main content of the thesis are asfollows: First this paper introduces the common wireless positioning, UWB wirelesspositioning the basic definition, characteristics and corresponding advantages. Thispaper elaborates on the importance of synchronization problems in UWB system andresearch value and the research status at home and abroad.From TOA, AOA, TDOA, RSS, the theory of UWB wireless location isdiscussed in detail. Often used in the localization algorithm is given to the leastsquares method and the weighted generalized least squares method, and made adetailed derivation.For high precision of the simulation, a single base station UWB positioningsystem is designed. The construction of base station system, positioning label hasmade the detailed design in this paper and this is the foundation for the followingposition synchronous simulation. The selection of UWB signal pulse, the UWBmodulation and receiving issues is also considered.Based on IEEE802.15.4a channel of communication protocol, a UWBpositioning based on single base station communication frame structure is designed,mainly illuminates the synchronization head structure and function, extends thefunctionality of the physical layer protocol header, and finally designs the timestampstructure for transmission of time information.Classical two-way ranging algorithm is introduced, and then puts forward a kindof clock synchronization algorithm used for estimating the clock frequency deviationand displacement between tag and the base station of the clock. On the basis of thesync pulse a algorithm to estimate the signal propagation delay is discussed, in theframe synchronization level incoherent reception algorithm based on energy ispresented.