High-Resolution Time Delay Estimation And Positioning Technologies Of UWB System In Indoor Multipath Environment

Ultra-wideband (UWB) communication is a novel short-range wireless communication technique, in which data are transferred using non-sinusoidal pulse with very short duration. It has many characteristics, such as good radio penetration through structures, good security, high transmission rat, low power consumption and exceptional multi-path immunity. UWB refers to signals which spread across many frequency bands and can not be transmitted as high power, so its application are mainly in short-range communication.In the thesis, high-resolution time delay estimation and positioning technologies of UWB system in indoor multipath environment are stusied. The research problem is mainly about range-besed UWB positioning method and UWB time delay estimation. The correlator is commonly used to obtain time delay estimation in conventional wireless positioning system. However, UWB signal propogation often suffers from multipath environment. If time delays are estimated where the multipaths are spaced closer than the duration of one pulse, a high resolution time delay estimation method must be used.In the thesis, after studying UWB indoor multipath channel model and TOA estimation signal model, we find the comparability of DOA and TOA. According to DOA estimation methods, we propose new methods of UWB high-resolution multipath time delay estimation.The main research work of the thesis is as follows:(1) The accuracy requirements of UWB indoor positioning system are expatiated. The application, background and current situation of UWB positioning system are point out, in which it focus on analyzing range-besed UWB positioning method, including the geometry principles of trilateration and multi-lateration based TOA localization and TDOA localization, nonlinear equation solution algorithms,and current UWB positioning technique.(2) In order to solve the problem of high-resolution time delay estimation of UWB system in indoor multipath environment, by studying DOA estimation method and construction delay matrix, Eigen Vector (EV)-based UWB signal high-resolution time delay estimation algorithms and frequency domain ESPRIT-based UWB signal high-resolution time delay estimation algorithms are proposed, respectively. The computer simulations are conducted in indoor multipath environment to confirm the validity of the proposed methods.(3) The forward-backword spatial smoothing technique in DOA estimation is developed in TOA in order to solve the problem of the lack of the delay matrix rank. A UWB signal high-resolution time delay estimation algorithms when the amplitudes of signal multiple channels are coherent is proposed based on frequency domain forward-backword smoothing and ESPRIT technique. The computer simulations are conducted in indoor multipath environment to confirm the validity of the proposed methods.This thesis is divided into six chapters, the concrete arrangement is as follows:Chapter 1, the requirements of UWB indoor positioning system and the positioning accuracy and application are expatiated. The main methods, current situation and problem of UWB positioning are analyzed.Chapter 2, range-besed UWB positioning method is mainly studied, including the geometry principles of TOA and TDOA localization, nonlinear equation solution algorithms, and current UWB positioning techniques.Chapter 3, an EV-based UWB signal high-resolution time delay estimation algorithms are proposed. The the proposed methods are simulated in indoor multipath environment to confirm its validity.Chapter 4, a frequency domain ESPRIT-based UWB signal high-resolution time delay estimation algorithms are proposed. The the proposed methods are simulated in indoor multipath environment to confirm its validity.Chapter 5, the UWB signal high-resolution time delay estimation problem when the amplitudes of signal multiple channels are coherent is studied. An ESPRIT algotithm based on frequency domain forward-backword smoothing technique is proposed. Finally, simulations are conducted.Chapter 6, the total paper is summarized, and the problems to be further studied are pointed out.