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GPS Multipath Mitigation by SQP Method
|Authors: ||Guang-Kai Li|
|Contributors: ||NTOU:Department of Communications Navigation and Control Engineering|
Sequential Quadratic Programming method;multipath
|Issue Date: ||2013-10-07T02:58:07Z
|Abstract: ||由於GPS的蓬勃發展，個人導航裝置(PND)已經成為現今最炙手可熱的電子產品之一，但也由於其應用層面的廣泛，產生了許多新的問題必須解決。在此我們將重心放在非視線傳播(NLOS)下的多路徑(Multipath)問題上，此種無線電信號並非經由一直線從發射端到達接收端的情況在現今高樓大廈林立的都市中幾乎是無法避免的，特別是對於GPS來說，其所造成的傷害更甚於電離層的影響。 本論文提出了一種叫做逐步二次規劃法的定位方法，藉由準確的估測並移除多路徑來獲得比其他傳統的定位方式更加精確的座標。此外，本方法是直接從定位演算中求解出多路徑，並不需要再從信號處理方面下手。|
PND (Personal Navigation Device) has become one of the daily consumer electronic products. With the help of satellite navigation systems (such as GPS), an off-the-shelf PND may provide meter-level positioning accuracy in a timely manner. As the field of applications getting broader, many different aspects that did not consider in the original system design have now introduced extra difficulties in modern day's navigation devices. For the problems that occur in today’s navigation application, we mention among others that non-line of sight (NLOS) reception of the navigation signal may drastically degrade the quality of the positioning result. Although NLOS problem has already addressed as an important issue when GPS product hit the market, it becomes much more critical when using a PND in an urban canyon environment, which is an application that wasn’t foreseen when GPS was first invented. Multipath error caused by signal reflections, diffractions, and scatterings is one of the most important problems in urban navigation. For satellite navigation, it may be seen as the major error source other than the ionosphere propagation delay. In this paper, a SQP (sequential quadratic programming) method for GPS positioning and multipath mitigation is proposed. The present method can effectively eliminate the NLOS (non-line-of-sight) delay errors and is also able to improve the location accuracy of a satellite navigation receiver. In our experimental result, it is demonstrated that the proposed estimator can compute the coordinate of a user location in an accurate fashion after estimating and removing the measurement biases. The proposed method is well suitable in the positioning domain in contrast with traditional GPS multipath mitigation methods which usually apply in the signal-processing domain.
|Appears in Collections:||[通訊與導航工程學系] 博碩士論文|
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