行動計算環境中有效率之協同快取置換機制

Abstract

由於近年來行動傳輸技術的快速發展，人們可以經由無線網路隨時隨地存取各式各樣的服務。值得注意的是，由於手持裝置的快取空間和傳輸頻寬是有限的。若我們能有一個適當的快取置換機制，則等待服務的時間就能減少。在這篇論文中，我們專注於在無線行動環境上的快取問題。藉由整合客戶端和基地台端的快取空間，我們提出了一個有效率的協同快取置換演算法。在我們提出的演算法裡，我們推導出一個包含了數個重要因子的得益方程式，並且同時考量了區域性服務以及非區域性服務。藉由此方程式，我們可以評定出每一個儲存在快取空間內資料的得益值，以利將來的快取置換。除此之外，我們更發展了一個介於客戶端和基地台端之間的協同機制。實驗結果顯示出我們提出的方法是非常有效率且優於傳統的快取置換機制。

Owing to the recent great advances in mobile communication technology, more and more information services are available via wireless networks. As such, users are able to access a variety of services from anywhere at anytime. Note that with proper caching mechanisms, the response time of services is reduced. Due to the limited size of local cache and transmission bandwidth of handheld devices, in this paper, we address the cache problem of mobile computing environments. By integrating cache usages in both mobile devices and base stations, we propose an efficient collaborative cache replacement (referred to as CCR) algorithm. In our proposed algorithm, we derive a profit function which includes several important factors of both location dependent service and location independent service. In light of the profit function devised, we can evaluate the profit of each cached service object for cache replacement. In addition to deriving a profit function, we further develop a collaboration mechanism between mobile devices and base stations. The experiment results show that the proposed CCR is very effective and outperforms the conventional cache replacement policies.