無線隨意網路中考量連結穩定度的協同資料快取方法

Abstract

在無線隨意網路的環境下，因為網路拓樸經常變動 ，節點間的連線時常會中斷，導致網路斷裂的情形發生。為了要解決網路斷裂的問題，可以使用資料備分。資料備份的策略考量每個節點該備份哪些資料項，以提升整體的資料存取的效率。現有資料備份策略中，各節點只考慮快取對自己最有益處資料;或是有考慮周圍節點的資料需求，但並未考慮節點間連線的穩定度。\n在本論文中，我們提出一個考慮節點連線穩定度的資料備份策略，我們考量節點間過去一段時間的連接穩定度，決定該備份哪些資料項。若兩節點過去的連接情況越穩定，則兩節點會備份對彼此都有益的資料項。經過實驗結果顯示，我們的資料備份方法對於資料的可存取性和請求延遲，皆有不錯的表現。

In a Mobile Ad Hoc Network (MANET), a mobile client moves freely in the network. The mobility of a mobile client causes the rapidly change on the network topology, unstable connection between mobile nodes and frequent network division. To solve these problems, data caching is proposed. In a data caching method, each node considers which data items should be cached in its local storage to improve the system performance. In the existing data caching approaches, a mobile client usually stores data items that favors the client itself and, sometimes, its neighbors. However, very few researches take into account of the link stability between mobile clients. In this paper, we propose a data caching scheme that takes into account of link stability. We measure link stability between two mobile clients by their link conditions in a recent period of time. If two nodes connect frequently in this period of time, the link is deemed to be more stable and the two mobile clients tend to be more cooperative in caching data items. Through an experiment using NS2, we showed that our scheme offers better performance in terms of data accessibility and query delay.