在現代都市中，計程車帶給乘客便利且快速的交通服務，為了降低乘客等待的時間與計程車空繞的時間，有效率的計程車呼叫協定成為重要的問題。在車用網路的環境下，我們提出分散式計程車呼叫協定。我們考慮計程車的行車方向與交通規則的限制，計算計程車到達乘客位置的行駛距離，作為計程車競爭載客的條件。我們設計利用計程車實際行駛到乘客的路徑作為回覆訊息的路徑，讓行駛路徑短的計程車訊息可以較快到達乘客位置，乘客即可回覆確認訊息給最快到達的計程車，以完成計程車呼叫協定。並且我們將計程車的競爭資訊留在經過的路口，讓其他競爭者可以提前知道競爭的結果，以減少計程車在競爭模式的等待時間，讓競爭失敗的計程車可以繼續尋找其他乘客。在模擬的結果中顯示，我們所提出的分散式計程車呼叫協定比過去的方法有效降低計程車行駛到乘客的距離，如此減少計程車司機油料的浪費與乘客等待時間。同時我們也降低計程車在競爭模式的等待時間，提高計程車載客的機會。 In the modern city, taxis offer the convenient and fast transport services to passengers. In order to reduce the waiting time of passengers and vacant time of taxi, the taxi hailing schemes become an important research issue. In this thesis, we proposed a distributed taxi hailing protocol in vehicular ad-hoc networks. Passengers could use their handheld devices with wireless communications to hail a taxi through the vehicular ad-hoc networks. The taxis that have the shortest moving distance to the passengers will get the chance of the services. Furthermore, we compare the moving distances of different taxis on the way of transmission and a reject message will be sent to the taxi that has the longer moving distance. Therefore, the taxi drivers who have longer moving distance could reduce the waiting time when they get the result of competition early, and then they can search other passengers. The proposed protocol cannot only reduce the vacant time of taxis also reduce the waiting time of passengers. The simulation results show that our scheme could find a vacant taxi which has less moving distance than previous work. Therefore, our scheme can save the fuel cost of taxis and the waiting time of passengers, and we also reduce the waiting time of taxis in contention mode to increase the chance of vacant taxis finding passengers.
