- 學位論文
在車載隨意行動網路上考慮交通號誌燈之延遲時間限制的繞徑協定
A Delay-Bounded Routing Protocol with Traffic-Light for Vehicular Ad Hoc Networks
摘要
在車載隨意行動網路中，車輛繞徑協定能被使用在告知緊急事件上，像是車禍 或塞車的情況。因此，許多研究集中在點對點的延遲路徑協定上。然而，一些像是 電子郵件或檔案傳輸協定的應用其關鍵是時間和無線電頻譜是一種有限的資源。因 此，延遲時間限制繞徑協定的目標是在用戶定義的延遲時間內並減少使用無線電情 況下將訊息傳送到目的端，這項目標已經成為一個重要的議題。延遲時間限制繞徑 協定可以藉由混合車輛攜帶或是無線傳輸的方式機訊息傳送至目的端。當用戶定義 時間足夠時就使用車輛自行攜帶訊息的方式，相反的則使用無線電傳輸的方式傳送 訊息。在市區的環境下，擁有許多紅綠燈，這項因素可能會大大的影響延遲時間限 制繞徑協定。現存的協定並沒有考慮到紅綠燈這項因素，因此可能會使用不當的傳 遞策略導致浪費大量的時間。例如：當遇到紅燈時，不過時間還是充足的情況下， 車輛採取繼續保持自行攜帶訊息的策略等待，不過因為紅燈的關係必須繼續在原地 停止等待，因此浪費了等待的時間。為了改善先前的協定，我們提出了一個新的延 遲時間限制繞徑協定，將紅綠燈這項影響因素考慮進來，每當車輛經過路口時，將 會獲得燈號和道路的交通負載的訊息，藉此可以更精確的預測並採取更適當傳遞訊 息的策略。模擬結果顯示，此延遲時間限制繞徑協定可以更有效率的使用時間並且 減少使用無線電傳遞訊息的次數。
並列摘要
In vehicular ad hoc networks, vehicles may use a routing protocol to inform emergent events, e.g. car accidents or traffic jams. Hence, many of the researchers are focus on minimizing the end-to-end delay of the routing protocol. However, some applications, e.g. email or ftp, are not time critical and radio spectrum is a limited resource. Hence, delay-bounded routing protocol, whose goal is to deliver messages to the destination within user-defined delay and minimize the usage of radio, has become an important issue. The delay-bounded routing protocols deliver message to the destination by the hybrid of data muling (carried by the vehicle) and forwarding (transmitted through radio). When the available time is enough, the message will be delivered by muling, otherwise, it will be delivered by forwarding. However, in an urban area, there are many traffic lights, which may greatly affect the performance of the delay-bounded routing protocols. Existing works do not consider the effect of traffic lights and hence it may adopt an improper deliver strategy and thus wastes a lot of available time. For example, when the traffic light is red and there is still enough available time, a vehicle may decide to adopt the muling strategy but it cannot move because of the traffic light and thus waste of time. To improve previous works, we propose a novel delay-bounded routing protocol which has considered the effect of traffic lights. Whenever a vehicle pass an intersection, it will gather the information of traffic light and traffic load of the next road section and thus it can make a more precise prediction and adopt a more proper strategy to deliver message. Simulation results show that the proposed protocol can make a better usage of the available time and uses less radio resource to deliver the message in time.