使用IEEE802.11無線區域網路系統之OTDOA/AOA混合定位

Abstract

位置估計在無線網路中有很多應用，許多方法已經被提出在解決定位的問題上。其中，觀測到達時間差(observed-time-difference-of-arrival, OTDOA)方法已經被運用於長程演進(long-time-evolution, LTE)系統之定位服務。在本篇論文中，我們將OTDOA定位的方法延伸其應用至IEEE 802.11無線網路系統，因目前多數擷取點(access points, AP)皆裝有多根天線，允許到達角度(angle-of-arrivals, AOA)估計方法的應用，因此我們提出一個混合OTDOA/AOA定位的方法。傳統的混合OTDOA/AOA方法是使用最小平方(least-squares, LS)演算法來解決定位上的問題。然而，我們已知TOA的觀測雜訊並不是白雜訊，而且OTDOA與AOA的觀測值對估計結果的會有不同的影響。因此，本研究提出使用加權式的最小平方法(weighted-least-squares, WLS)來提升定位效果，模擬結果顯示WLS演算法對於定位估計比LS更加準確。

Location estimation finds many applications in wireless networks. Many methods have been proposed to solve the problem. The observed-time-difference-of-arrival (OTDOA) method has been defined in long-time-evolution (LTE) systems for location service. In this thesis, we extend the use of the OTDOA method to IEEE 802.11 wireless local networks. Since many access points (APs) possess multiple antennas, allowing the estimation of signal angle-of-arrivals (AOAs), we then propose using a hybrid OTDOA/AOA localization scheme. Conventional hybrid OTDOA/AOA method uses an iterative least-squares (LS) method in solving the problem. However, it is known that the observation noise in time-of-arrival estimation is not white. Also, OTDOA and AOA observations may have different influence on estimation accuracy. We then propose an iterative weighted-least-squares (WLS) method to enhance the localization performance. Simulation results show that the proposed method outperforms the conventional method.