蜂巢式網路無線行動台定位技術研究
| Autor: | Chih-Ming Chung, 鍾志明 |
|---|---|
| Rok vydání: | 2006 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 94 In recent years, an exponential growth of wireless systems has been observed. Wireless technology has also entered the realm of consumer applications, as well as the industry, medical treatment, logistics, and many other applications. Since wireless information access is now widely available the demand local positioning systems draws significant attention. At present wireless localization technologies has emerged as an essential public safety feature of cellular systems. This has been in response to a recent federal order issued by the federal communications commission (FCC), which mandates all wireless service providers to provide public safety answering points with information to locate an emergency 911 caller with certain accuracy. However, many difficulties intrinsic to the wireless environment make meeting the FCC objective challenging; these challenges include channel fading, low signal-to-noise ratios (SNRs), multiuser interference, and multipath conditions. If positioning can achieve enough accuracy, the functions can be much beneficial to national defense and livelihood applications. This thesis mainly investigates mobile location technique under the cellular network. First of all, we proposed a covariance shaping least square estimation algorithm based on the TOA structure. Because that the CDMA signal is a low signal-to-noise ratio noise-like signal, so we proposes the method which makes it possible to have a lower estimation error in mobile location estimation. But if it is circumstance of large signal intensity environments, the estimation result would not be better than the traditional least square method. For the next, we can uses the TDOA localization method combined with the data fusion technology as a processing way to obtain a best estimation on the mobile station, on the condition that the statistical characteristics of the wireless propagation channel are already known. Therefore, based on the data fusion technique structure we proposed one kind least square estimation method unify two steps least square algorithm and covariance shaping least square algorithm. Under this structure, we use the merit respectively of two steps least square method and covariance shaping least square method to achieve the better localization performance. Simulation results show that the collaborative location method based on the data fusion structure can effectively promote the accuracy of mobile location. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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