- 學位論文
以分支度強化需求式群播向量路由 維護機制
Advanced route recovery based on degree in MAODV
摘要
行動隨意網路毋需建置任何基礎通訊設施，擁有自我建構、自我組織、自我管理特性的網路。它由行動節點組合而成，封包的傳送經由節點以多點跳躍方式作傳遞。在群播路由中，由於節點的移動性，易使得路徑失效而降低封包傳遞率。 本研究提出以分支度強化路由維護策略，探討行動隨意網路如何利用樹狀結構分支度和群播樹資訊傳遞的策略，以減少因節點移動而影響路由的有效性。需求式群播距離向量路由策略之路徑維護方式中，其令節點皆具有相同的等待時間，若在此時間內未接收到上游節點所傳送的任何封包時，才判定路由失效，並啟動路由修補。但此一被動式路由維護，未區隔主要路徑斷裂和一般路徑斷裂下兩者封包遺失率的差異性；且相同的等待時間無法確實得反應網路現狀，容易遺失封包而降低傳送率。我們提出以分支度強化路由維護策略，藉由樹狀拓樸之分支度來判斷，使主要路徑上的節點發現路由斷裂後能即時的反應；並可由群播樹資訊的傳遞得知較佳的群播路徑時，啟動區域路由修補，以提升封包傳遞之效率。 經由模擬結果分析，本策略可改善原需求式群播距離向量路由的維護機制，提升封包傳遞率和降低封包傳送成本。
並列摘要
Mobile Ad Hoc Network (MANET) needs no infrastructure. Its characteristics of network include self-creating, self-organizing and self-administrating. It consists of mobile nodes. Packets are routed and forwarded via multi-hop peer-to-peer protocol between nodes to the destination node. In multicast routing of MANET, the mobility of mobile hosts frequently make the routes broken, and leads to the lower data packet ratio. The purpose of this study is to propose “An advance route recovery based on degree” to reduce the link breakage for the tree-based topology of multicast in MANET. For the Multicast Ad hoc On-demand Distance Vector (MAODV), the route maintenance could detect the link breakage when the node does not receive any packets from the upstream node after a certain time. However, the re-active route maintenance does not the different influence on different tree degree, and the same waiting time cannot reflect the real topology situation. MAODV initiates tree repair after some nodes losing packets, but it reduces the delivery rate of data packet. Our proposes an advance route recovery based on degree for the MAODV. The node based on the tree degree could obtain better link information from the structure of multicast tree, and initiates tree repair to promote the efficiency of routes in MANET. The simulation results show that the advance route recovery based on degree could improve the route maintenance of MAODV, increase the delivery rate of data packet and reduce the control overhead.