| 摘要: | 路由是組成網路的一個基礎，為了讓MANET實現，高效和有效的路由協定是一個關鍵的議題。基本上路由協定可先畫分成兩大類，單播(Unicast)和多播(Multicast)。在MANET的應用領域中，快速的開發(Rapid development)和動態的重建(Dynamic reconfiguration)是很重要的。像是戰場上的軍用設施、醫療研究、救援地點，或是參與者需要使用移動裝置並且交換訊息的場合。這些應用使得多播操作變得受到重視。像是在需要傳送多件副本資料時，即可節省很多時間。並且降低傳輸消耗(Transmission overhead)和能量消耗(Power consumption)。因此多播路由在MANET中扮演著一個極為重要的角色。
在多播路由協定中，以一個多播群組來看，拓樸的建立、群組結構的維護、資料傳輸的方式、資料傳輸路徑的途徑都是需要探討的議題。在此大方向底下，我們以拓樸建立的初始化以及資料傳輸路徑的優化為優先考量因素。因為在此階段所構成的重要性較為明顯，一個好的路由即使在傳輸方式或演算法上有較好的成效，但是在拓樸建立初期若是沒有好的基礎，也只是在挽回拓樸資訊的缺陷和誤差。再來則是資料傳輸路徑的選擇，當資料流量變大，網路頻寬固定的情況下，在路徑的選擇上變是很重要的一環。
在本論文中，以模擬結果來證明所提出之假設。我們提出的方法中，控制封包的總量，會比舊有的方法來的多，因為我們在路徑的維護上，節點會周期性廣播控制封包來做路徑的維護，並且每個節點會依控制封包來維護鄰居結點表。雖然當節點數目或群組數目較少的時候表現不亮眼，但是當數量增加，我們機制的啟用，所達到的效能可以彌補在過多控制封包使得傳輸延遲時間增加的損失。也因如此，我們在封包傳輸的成功率上，呈現出較高的表現。
整體來說，我們在控制封包的使用上，相對消耗較多資源，但是我們以額外的控制封包來增強我們在正確路徑的建立以及路徑的最佳化，以達成整體效能之效果。
Mobile Ad-hoc Network (MANET) usually apply mobile devices communicate with others, without additional base station. Along with time vicissitude, technical developed, in the same area, the mobile devices increased, so communication between devices become much complicated. Data bandwidth is constant, but data flow increased, it makes usage of control packet and maintain of transmission path between nodes become an important issue. How to make data transmission and path maintain more efficient in incremental nodes with better routing protocol is a good research topic.
There are many problems need to overcome in routing protocol. According to difference of topology in MANET, it can be separated into mesh based and tree based. Based on mesh, in the beginning of building topology and establish routes need lots of control packets to set up and maintain. It has good performance on stability of path and repairing invalid path. In tree based, it has a core node to manage members in a group. It means in every group there is a node to maintain its members. Control packets will be reduced greatly. The path between source and destination is single, it will be impact when the path invalid. On the other hand, in mesh based, each node has one or more path to source or destination and it can change path in time then keeping transmitting data. Relatively, it needs more control packet on maintain path and topology, thereby affects transmission of data flow. In recent year, data flow and receiver are tremendously increased, the excessive control packets affect not only transmission of data but delay time of delivery even ratio of successful delivery. Therefore, it is good research topic to use tree based on routing even with path stability problem if the cost of path building and maintain can be less than the cost of repairing invalid path.
In this paper, we proposed an advanced label based and tree based multicast routing protocol. With new label mechanism when new topology builds, and backup path selects. This improvement reduces control packets and maintain data transmission path with backup route. When data flow dramatic increased we still keep good delivery ratio. In simulation results, our control packets are a little more than other method, but our delivery ratio keeps in a good statue even better than others. This is also our approach highlights |
