利用WiMAX訊號特徵比對的健全定位方法

近年來由於行動裝置的數量不斷攀升，適地性服務 (location-based services)跟著興起，這使得定位準確性和效率變成越趨重要的議題。全球定位系统 (Global Positioning System, GPS)是最廣為人知的定位技術。GPS在開放空間擁有相當高的準確性，但都市戶外大樓林立，GPS的準確性和可達性會因為樓房障礙物的存在而降低。除了GPS定位之外，實務和研究領域都有相當多使用無線訊號的技術，這些訊號包括全球行動通訊系統 (Global System for Mobile Communication)、Wi-Fi和全球互通微波存取 (Worldwide interoperability for Microwave Access)。相關無線訊號定位研究主要都測重訊號強度特徵比對，但我們發現對同一個地點而言，某些基地台的訊號強度會隨著天氣而改變，另外，無線訊號強度也都一定程度受大樓障礙物所影響。我們提出一個健全且新穎的定位方法，該定位方法利用前次與今次定位差的回溯方式混合了一個既有的K最近鄰法(K nearest neighbors)，和兩個我們提出的格框平均訊號強度比對法 (Grid average Signal Strength Matching)及考量天氣因素訊號差比對方法 (Signal Difference Matching)。我們的研究包含了完整的實驗流程和方法，同時也和多種定位方法比較，這其中包含了決定性(deterministic) 和機率性 (probabilistic) 特徵比對法 (fingerprinting technique)。我們方法的中位誤差是52公尺，美國聯邦通信委員會準確性和穩定度都比其他方法好。該方法考量了天氣因素，且無需任何基地台的位置資訊，且可以用於沒有GPS的行動裝置上或作為輔助定位之用。

關鍵字

定位；定位準確度；健全性天氣；訊號差；地點；位置；特徵比對；決定性；機率性； WiMAX ； GPS ；適地性服務；行動裝置；運輸

並列摘要

Due to the rising amount of mobile devices and location-based services (LBSs), the accuracy and efficiency of localization become a more and more important issue. Global Positioning System (GPS) is the most well-known positioning techniques; it can provide highly accurate location results in open sky environments, but its accuracy and availability declines in outdoor urban canyons. Beside GPS, radio signals are used for localization both in practice and in research; these signals include Global System for Mobile Communication (GSM), Wi-Fi and Worldwide interoperability for Microwave Access (WiMAX). Related work of wireless positioning mostly rely on signal strength, but we know that signal strength differs in different weathers; reflection and signal decay when passing through obstacles are also problems. Thus, we proposed a robust positioning method using the hybrid of a deterministic method K nearest neighbor(s) (KNN) and two novel techniques including Grid average Signal Strength (SS) Matching and Signal Difference Matching for location estimation, which puts weather conditions into concerns. Also, we performed a complete experiment and done accuracy and robustness evaluation of our positioning method along with other deterministic and probabilistic techniques. Our positioning method reaches a median error 52 meters, which is much superior than the accuracy requirement (latitude and longitude of emergency callers within 300 meters) of Wireless enhanced 911 from the U.S. Federal Communications Commission (FCC), and shows better accuracy and robustness than others; it doesn’t require any pre-knowledge of base stations and can be used on GPS-free mobile device or supporting GPS.

並列關鍵字

Positioning ； Positioning Accuracy ； Robust ； Weather ； Signal Delta ； Signal Difference ； Location ； Localization ； Fingerprinting ； Deterministic ； Probabilistic ； WiMAX ； GPS ； LBS ； Mobile Device ； Transportation

參考文獻

[9] “Available Measurements in Current WiMAX Networks and Positioning Opportunities,” Mussa Bshara and Leo Van Biesen, IMEKO, 2009

[26]“Transferring Localization Models Across Space,” Sinno Jialin Pan, Dou Shen, Qiang Yang and James T. Kwok, Proc. AAAI Conference on Artificial Intelligence, 2008

[2] “RSS-based localization in environments with different path loss exponent for each link,” J. Shirahama and T. Ohtsuki, Proc. IEEE Vehicular Technology Conference, 2008

[4] “Sensor Measurements for Wi-Fi Location with Emphasis on Time-of-Arrival Ranging,” Stuart A. Golden and Steve S. Bateman, IEEE Transactions on Mobile Computing, 2007

[5] “A Generalized Subspace Approach for Mobile Positioning With Time-of-Arrival Measurements,” H. C. So and Frankie K. W. Chan, IEEE Transactions on Signal Processing, 2007

國際替代計量

利用WiMAX訊號特徵比對的健全定位方法

全文下載

主題瀏覽