隨著國民經濟和科技的發展，車輛擁有的人數也越來越多，由於過多的車輛，造成交通環境壅塞以及混亂，進一步危害人民的生命和財產的損失。為了確保交通行駛上的安全，結合電子資訊技術發展的安全防碰撞機制被廣泛的討論。近年來，由於車載網路通訊技術(WAVE/DSRC)的成熟。大部分車輛安全應用可以結合車輛定位和車載通訊達到防碰撞的目的。在車載環境中，全球定位系統(GPS) 已被廣泛的使用於定位系統導航中。但是GPS會被許多環境因素(例如:多重路徑效應、大氣層的離子濃度變化…等)影響定位準確性，使得無法滿足車輛安全應用的需求。為了改進GPS車輛定位的準確性，我們提出一個可於在車載環境中的協同式車輛定位準確度提升的方法。並於實驗數據中呈現我們演算法在車載現實環境中，也可達到很好的效能提升。

With the advancement of technology and the economy, people are more in-clined to buy cars. However, as a result, people forfeit their lives and property through accidents due to traffic congestion and traffic chaos. To ensure driving safety, anti-collision warning applications have been widely discussed. Most vehicular safety applications use vehicular positioning and vehicular communication technologies to avoid car accidents. With VANET, it is common to use the Global Positioning System (GPS) as the vehicular positioning tool owing to its comprehensive development in vehicular navigation. However, there are factors that affect GPS positioning accuracy (e.g., multipath effect, atmospheric effect, etc.). In order to improve the GPS vehicular positioning accuracy, we propose a Cooperative Positioning algorithm that can improve the localization accuracy. We also demonstrate that our algorithm can work well in a real city environment.

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