基於3G行動通訊網路訊號之即時交通資訊

Abstract

近年來，隨著科技的發展，手機已經廣泛為大眾所使用，有鑑於此，我們將利用手機的換手(Handover)行為，求出道路中行進手機換手位置，並利用無線電信網路追蹤使用者手機位置的方式，產生即時道路交通路況資訊。這個機制不需要花費龐大的經費來架設及維護道路上的車輛偵測裝置(Stationary Vehicle Detector (SVD).)。而且手機幾乎是無所不在的，因此我們以追蹤手機位置所得到的交通資訊是非常即時且全面的。本研究提出利用一般位置更新(Normal Location Updates, NLU)及利用被選擇的換手(Selected Handovers, SHO)二種方法來計算取得CFVD車速，並以高速公路上之車輛偵測器所取得的車速做為參考依據。 在一般的情況下，利用NLU的方法可以獲得相當不錯的交通資訊估算，但因為連續兩次NLUs所涵蓋的路段較長，導致如果塞車發生在連續兩次NLUs中間路段較為上游的子路段時，沒辦法很即時的反映出塞車的情形，有鑑於此，我們希望利用換手(Handover)資訊來提升此長路段的交通資訊解析度，但是利用換手資訊估算交通資訊時，我們面臨換手位置不明確的問題，故我們會提出如何篩選出SHO並利用來估算這些距離較短的子路段的交通資訊，以解決子路段塞車時無法及時回報的問題。由於利用SHO得到的速度回報是較少的，所以我們再更進一步地利用手機來電(call arrival)與掛斷(call complete)來預估子路段的交通資訊。利用以上的方法我們可提供準確的即時交通資訊。

Since traffic congestion occurs frequently in urban areas, Traffic Information Systems (TIS) have been constructed to provide road users and traffic managers with accurate and reliable real-time traffic information. Traffic monitoring based on cellular network data, also referred to as Cellular Floating Vehicle Data (CFVD), can be more cost-effective than traditional approaches, such as roadside sensors, because no field installation or maintenance is needed. Consecutive handover events of a handset on a moving vehicle can be used to estimate traffic speed. However, when traffic congestion occurs, handover events are rare, and thus there may be no traffic speed reports from CFVD. Furthermore, the location where mobile stations perform a handover procedure from one cell to anther is imprecise. Thus in this paper, we design novel effective CFVD algorithms to generate traffic information. Using Normal Location Update (NLU) events, we can obtain accurate traffic speed a freeway segment of length about 10 km. Moreover, Selected Handovers (SHOs) that exhibit no cell oscillation problem were used to estimate traffic speed for shorter road segments,. Furthermore, we use call arrival and call completion events to enhance the quality of traffic estimation using CFVD.