Research On Semantic Caching Replace Strategy For Location Dependent Query In Mobile Computing Environment

In Mobile Computing Environment, narrow bandwidth, frequent networkdisconnections and limited client resources can be solved by data caching. Semanticcaching is a caching scheme based on the describe of semantic information of thecustomer query. Since semantics about the cached items are stored in semantic caching,the client is able to determine whether a query can be totally answered and how muchcan be answered. Especially for location-related queries, semantic caching can improveperformance of access to data caching. This article studies the replacement strategy ofsemantic caching in the mobile environment.This paper focuses on the research on the feature of Mobile computingenvironment and Location Dependent Query and Semantic caching, and on the analysisof cache replacement policy which is relatively mature currently. And based on that, thethesis provides another two new Semantic caching replacement policies: Access andUpdate Frequency Furthest Away Replacement and Prioritized Lowest CostReplacement. AUF-FAR algorithm adds the cost function to the standard of replacement,not only think about distance but also frequency of visitation and update，to avoid theweakness of only think about semantic segment distance in FAR. PLCR takes someimportant factors into account such as access probabilities, update rates, data distance,valid scope to ensure the maximum utilization of limited cache, the PLCR cachereplacement strategy decides the data replaced according to the value of the lowest costfunction.Finally, this paper carries on experiments to verification the quality of the twocaching replacement strategies and the quality of FAR and PAID, and the qualitybetween of the two new themselves. The result shows that both hit rate and responsespeed of AUF-FAR and PLCR are relatively improved. In different testing environments,AUF-FAR and PLCR have different merits.