UWB Ranging And Positioning Technology Investigation

Over the last years there has been a great deal of interest in Ultra wideband (UWB) wireless communication, especially following the approval of the UWB technology by the FCC (Federal Communications Commission) in February 2002, which is also result in an increasing research in UWB applications. UWB impulse radio makes up of ultra-short duration pulses which yield ultra-wideband signals characterized by extremely low power spectral densities and extremely wide frequency band. These systems are potentially immunity to multipath fading, with a low probability of intercept (LPI) and low power consumption. Its application in military field is becoming wider and wider because of the abilities to anti-jam, anti-detection and reduce power consumption. At the same time, as a promising technology for short-range indoor wireless communication, UWB systems have become a good candidate in the civilian applications as well.With the development of wireless communication network technologies and users' increasing requirement of various kinds of services, ranging and positioning in wireless communication network are playing a more and more important role. Several conventional positioning technologies, such as GPS Positioning; Positioning Based on Ground Network (Cell ID Positioning), have an limited application foreground because of their various disadvantages. Communication network based on UWB transmission has a good ability of anti-noise, anti-jam, resolving mutipath and penetrating walls, and is with a larger communication capability as well. Therefore, ranging and positioning based on UWB have immense advantages overthese conventional methods.In this thesis, after introducing the UWB wireless communication technology, we mainly finish two tasks just described as follows:First, based on the integrative analysis of former papers, the main ranging and positioning technologies used in UWB wireless communications are concluded. Respective advantages and disadvantages are listed, which is a valuable reference in practical applications.Second, a novel ranging and positioning method tailored for UWB impulse radio is proposed, in which TOA is estimated via calculating the correlation function between the transmission signals and local signals to accomplish ranging. Since whether the ranging process would be terminated is under the controlling of detector output, the ranging speed is greatly improved. Then LSE minimizing algorithm is token advantage of to seek the coordinates of the target node. This section is the center of the whole thesis. The basic principle, preconditions and process of implementation of the novel method are presented in detail. The relationship between ranging error and SNR, the time delay between two adjacent correlators, the autocorrelation function of pseudo-random codes used in ranging are analyzed via simulation experiments. The comparison results with the method proposed in [31] are also presented. The results show that the method proposed here can accomplish ranging even under the condition of small SNRs, and is with a higher ranging precision and a faster ranging speed. At the same time, our method is immunity to noise and multipath. In a word, it will be taken into more consideration in the coming future.