在無線網路中，很多時候我們都必須使用到廣播或群播的機制；而一個最直接達成廣播之效果的方式，就是使用氾濫式廣播之方法 (flooding)。但是直接的使用氾濫式廣播之方法來作廣播或群播的動作時，通常都是非常的浪費成本而且會造成所謂的 “廣播風暴 (broadcast storm)” 之嚴重的問題。所以在這篇論文中，我們將提出一個利用 ”繞路訊息之交換” 來建立轉送群組 (forwarding group) 的一種方法，並進而想要減少轉送群組中的成員，以減少廣播時，所造成之不必要的重覆廣播之影響。而這裡所謂的轉送群組就是一群網路上的節點，負責將收到的資料作轉送的動作。使用轉送群組的主要目的，是為了要利用一群網路上的節點來負責維護網路中所有節點的連通，即維護整個網路的連通性，以減少資料的重覆傳送。

由於我們的方法將儘可能地建立一個最小的轉送群組，因此如能利用這個轉送群組資料傳送與否的考量，我們將可以儘可能地的減少廣播或群播時所造成的額外傳送負載。而建立這個群組所採用的方式是找尋所有網路上的節點到根節點的最短路徑，並將這些路徑上的所有節點除了本身以外都選為選為轉送群組的成員。在這裡所提出的方法，主要是利用Distance Vector的繞路方法來作轉送群組的更新及維護；並且由於所利用的繞路協定是被用於動態改變的網路上，所以這個轉送群組的建立及維護方法，亦可以適應在有節點移動的網路上。

此外，由於所利用的繞路協定，可以防止資料傳送造成迴路，因此利用這個繞路協定，我們可以防止資料在轉送群組幫忙轉送資料時有迴路也發生。這個建立轉送群組的方法並不使用任何明顯及額外的控制封包來達成轉送群組的建立及維護，反而是利用繞路訊息在交換的同時達成轉送群組的建立及維護。所以並不會產生任何明顯負載。

Broadcasting is a fundamental primitive in local area networks (LANs).Operations of many data link protocols, for example, ARP (Address Resolution Protocol) and IGMP (Internet Group Management Protocol), must rely on this LAN primitive. To develop the broadcasting service in mobile ad hoc wireless LANs (WLANs) is a challenge. This is because a mobile ad hoc WLAN is a multi-hop wireless network in which messages may travel along several links from the source to the destination via a certain path. Additionally, there is no fixed network topology because of host moving. Furthermore, the broadcast nature of a radio channel makes a packet be transmitted by a node to be able to reach all neighbors. Therefore, the total number of transmissions (forward nodes) is generally used as the cost criterion for broadcasting. The problem of finding the minimum number of forward nodes in a static radio network is NP-complete. Almost all previous works, therefore, for broadcasting in the WLAN are focusing on finding approximation approaches in a, rather than, environment. In this paper, we propose a novel distributed protocol in WLANs to significantly reduce or eliminate the communication overhead in addition to maintaining positions of neighboring nodes. The important features of our proposed protocol are the adaptability to dynamic network topology change and the utilization of the existing routing protocol. The reduction in communication overhead for broadcasting operation is measured experimentally. From the simulation results, our protocol not only has the similar performance as the approximation approaches in the static network, but also outperforms existing ones in the adaptability to host moving.

中文摘要 I
英文摘要 III
目錄 IV
圖目錄 VI
第1章 導論 - 1 -
1.1 研究動機 - 1 -
1.2 論文架構 - 4 -
第2章 相關研究 - 5 -
2.1 轉送群組的建立 - 5 -
2.2 繞路協定 - 6 -
2.3 廣播 - 7 -
第3章 實作及想法 - 9 -
3.1 想法及實作概觀 - 9 -
3.2 方法 - 10 -
3.2.1 轉送群組的建立 - 10 -
3.2.1.1 加入轉送群組 - 10 -
3.2.1.2 退出轉送群組 - 13 -
3.2.2 減少轉送群組的成員數 - 14 -
第4章 效能評估 - 18 -
4.1 模擬環境 - 18 -
4.2 結果 - 19 -
第5章 結論 - 23 -
參考文獻 - 24 -
附錄：英文論文 - 26 -

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