車載網路上可靠的區域路由修補演算法之研究

A Reliable Local Routing Path Repairing Algorithm in Vehicular Area Networks

謝惇丞(Tun-Cheng Hsieh)

指導教授 ： 黃世昌

國立虎尾科技大學/電機資訊學院/光電與材料科技研究所/碩士(2011年)

摘要

近年來車輛通訊技術越來越重要，使得駕駛者或是乘客更能即時的得到目前路況資訊、危難救援、周邊商家和娛樂資訊，提供更確切的服務。然而多數的車輛通訊技術機制都不適合用於高速移動性的應用，若是直接採用容易使得無線網路連線頻繁斷裂。舊有應用在隨意網路(Ad Hoc Network)的路由機制將會嚴重影響無線網路的通訊品質，使得這些機制不適合用於車輛通訊。因此，高速移動性環境下的連線技術更是突顯其重要。

然而，高速移動應用的環境下，連線品質取決於連線的可靠度，連線的可靠度則是直接和車輛之間的連線壽命有確切的關係。因此，大多數的相關研究皆是連線壽命以及最短路徑的研究。如果只注重於車輛之間連線壽命時，車輛間連接的跳數(hop count)將會過多，導致無線網路產生過多的通訊開銷以及網路延遲。然而，我們發現光注重上述的兩個條件仍然不足夠，因為當資料傳輸的時間大於連線壽命時，資料還未傳輸完成連線就斷裂了，必須再重新建立一條路徑，這樣將會對網路造成更多的開銷以及延遲。

因此，在本篇論文中所探討的是高速移動的環境下，車輛中路徑維護的問題，論文所提的方法是改良AODV (ad-hoc on-demand distance vector)的機制，在最短路徑以及最長連線壽命路徑的網路拓樸建立完成後，計算資料傳輸所需的時間，尋找新的路由替代現有的路徑中無法滿足資料傳輸時間的連線壽命，在網路路由斷裂之前找到替代的路徑，使得資料傳輸能順利完成，確保網路連線的穩定度以及避免網路重新建造整條通訊路徑的額外開銷。在模擬結果中，我們可以發現我們所提出的方法在封包的傳送率上以及點對點的延遲上能遠遠的優於AODV協定，同時也提高網路的穩定度以及降低傳輸延遲。

關鍵字

車載通訊 ； 隨意網路 ； 路由協定 ； AODV ； 路徑修補 ； 連線壽命

並列摘要

Recently, the vehicle to vehicle (V2V) communication gradually becomes more and more important. Many vehicular communication technologies are developed for drivers or passengers to obtain real-time traffic information, accident rescue, location services and entertainment. However, most of the vehicle communication technologies are not suitable for high-speed mobile environment. These methods will cause network disconnecting frequently. The existing routing protocols used in Ad Hoc Network routing violate the communication quality. They are not suitable for V2V communication. Developing a new connection technology is more important on high-speed mobile environment.

The connection quality of high-speed mobile environment depends on the path reliability. The path reliability is closely related to the connection lifetime between vehicles. Therefore, most of the research focuses on extending the path lifetime and finding the shortest path. If we only focus on the path lifetime between vehicles, the hop count will increase the communication overhead and delayed. However, considering those two constraints is not enough. If the flow requires more time than the path’s lifetime, the path will break before data transmission finishes. The path will be rebuilt. It is not effective on the vehicle network.

Therefore, this paper solves the path maintenance problem on the high-mobility inter-vehicle communication. Firstly, we build the shortest and the longer lifetime path in the vehicle network. Next, we find the new path to replace the old one that the remaining lifetime is not enough for the traffic flow finishes its transmission. The simulation results show that the proposed method is better than the AODV protocol on the transmission rate and transmission delay. The results also show that the proposed method can increase the stability of connection.

並列關鍵字

V2V ； Routing Protocol ； AODV ； Route Repair ； Lifetime

參考文獻

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