都會區車輛隨意網路之多重路徑繞徑技術

Abstract

在車載隨意網路(VANETs)裡，節點(車輛)的高移動性而造成封包的遺失是一個很常見的問題，很多文獻嘗試去解決這個問題。CLA為基於道路之單一路徑繞徑技術協定，一旦路徑斷裂，它必須要再建立一條新的路徑。AOMDV和NDMR為多重路徑繞徑技術協定，若是一條路徑斷裂，它們會選擇另一條路徑。但是AOMDV和NDMR是基於節點來建立路徑的繞境技術協定，它們的路徑比基於道路繞徑技術協定建立的路徑還要容易斷裂。在本論文中，我們提出了一個基於路段之多重路徑繞徑技術(RBMR)協定。就我們所知，在現有文獻中還沒有基於路段之多重繞徑技術協定。我們嘗試從寄送者到接收者之間建立兩條最快的路徑。為了減少路徑斷裂的影響，我們利用即時的交通資訊，如位在傳輸範圍內的車輛識別碼，來建立並維持兩條基於路段且節點不共用的路徑。一旦一條路徑(第一條路徑)被建立好後，這條路徑會立即用來傳送封包。當第一條路徑斷裂後，下一條被建立的好路徑(第二條路徑)將會被使用。以即時的交通資訊為基礎，我們提出的RBMR，在每一段路段內，藉由車輛存在績分(VPS)的參數來選擇相對穩定的中繼點來傳送封包，以使封包傳輸更穩定。模擬結果顯示，我們提出的RBMR和AOMDV，NDMR和CLA相比較，分別提升了封包傳輸率9%、6%及15%，減少點對點的延遲時間28%、11%及7%，以及減少了額外控制負荷30%、25%及19%。

In vehicular ad-hoc networks (VANETs), packet loss is a common problem because of high node (vehicle) mobility. Many literatures tried to solve this problem. Connectionless approach (CLA) is a road-based single path routing protocol. If a route disconnects, it has to create a new route. Ad-hoc on-demand multipath distance vector (AOMDV) and node-disjoint multipath routing (NDMR) are multipath routing protocols. They can switch to another route if ones route is disconnected. However, since AOMDV and NDMR are node-centric routing protocols, a route is easier to be disconnected than that in road-based routing protocols. In this paper, we propose a novel road-based multipath routing (RBMR) protocol. To the best of our knowledge, there is no existing road-based multipath routing protocol. In the proposed RBMR, it attempts to establish two fast routes from sender to receiver. It uses real-time vehicular traffic information, such as the IDs of vehicles within the radio transmission range, to create and maintain two road-based node-disjoint routes to reduce the impact of broken links. Once a route (the first route) is first established, it will be used to send packets immediately. The next established route (the second route) will be used if the first route is disconnected. Based on real-time vehicular traffic, the proposed RBMR selects a relatively stable node as a relay node in a road segment based on the vehicle persistence score (VPS) for data forwarding. Simulation results show that the proposed RBMR improves the packet delivery ratio by 9%, 6%, and 15%, end-to-end delay by 28%, 11%, and 7%, and control overhead by 30%, 25%, and 19% compared with AOMDV, NDMR, and CLA, respectively.