應用於無線隨意網路的漣漪廣播

Abstract

在無線網路中，廣播服務是一個重要的應用。它的目的是將資料封包從一個源頭節點傳播到整個網路的其他節點。傳達率和接收延遲是兩個用來衡量廣播效能的方法。在無線傳輸的過程中，由於無線通道的波動，經常會出現封包遺失的情形。然而，現有的廣播方法很難在具有封包遺失的環境下呈現好的效能。在本篇論文中，我們提出了漣漪廣播(RIPcast)以達到有效和可靠的無線廣播傳輸。在網路中的節點以一個特殊設計的方法來傳播資料封包。漣漪廣播也使用噴泉編碼以更進一步提升封包傳輸的可靠性並增加資料傳輸的多樣性。模擬結果顯示在考慮封包遺失下，相較現有的廣播方法，漣漪廣播顯著地提升傳達率並降低接收延遲。此外我們將漣漪廣播應用於影像串流上。結果顯示漣漪廣播相當適合用於無線隨意網路的廣播傳輸。

Broadcasting service is an important application in wireless networks. The goal is to distribute data packets from one source node to all other nodes in the network. Delivery ratio and reception delay are the two primary measures for broadcasting performance. Due to the wireless channel fluctuations, packet loss is often seen in wireless transmissions. However, the existing broadcast schemes have difficulty achieving good performance under severe packet loss. In this thesis, we propose the rippling broadcast (RIPcast) scheme which is able to achieve reliable and efficient transmissions in wireless ad hoc networks. The nodes in the network are designed to distribute data packets cooperatively in a special manner. The broadcast scheme also adopts the use of fountain codes to further enhance the reliability as well as the diversity of data transmissions. It is observed from the numerical experiments that the proposed scheme significantly enhances the delivery ratio and reduces the reception delay under packet loss compared to the existing broadcast schemes. The performance of video streaming using RIPcast is also investigated. The results suggest that RIPcast is highly suitable for broadcasting service in wireless networks.