基于移动计算系统的动态缓存策略

A Strategy of Dynamic Caching in Cellular Mobile Computing Systems

对移动客户机的位置信息进行实时管理是移动计算系统中一个非常重要的问题。在传统的移动计算系统中,采用一种2层的位置数据库体系结构,这种结构可扩展性较差,不能适应具有大量移动客户机的网络应用。鉴于此,人们提出了树状位置数据库体系结构,系统中的位置数据库组成一个树形结构以方便移动用户进行位置查找。尽管树状结构将位置更新与查询的任务在所有位置数据库中进行了分摊,系统中仍存在位置更新代价较大及位置查询延迟较长的问题。基于此提出一种动态缓存策略,以减少位置更新和查询的代价。实验仿真表明,该动态缓存策略具有很高的执行效率,能大大的提高系统性能,具有很好的实用价值。

How to manage the real-time locations of mobile clients is one of the important issues in mobile computing systems. In the traditional cellular mobile computing systems, two-tier architecture was adopted and has performed well for a small number of mobile users. However, the two-tier architecture is not scalable, and cannot be apphed to the new mobile computing applications where a very large of mobile users exists. To solve this problem, a hierarchical database structure has been proposed recently. In the hierarchical structure, location databases of different cells are organized into a tree structure to facilitate the search of mobile chents. This architecture can distribute the update and searching workload amongst the location databases in the system. However, it has the problem of heavy location update overhead and long search delay. This paper researches how to generate location caching in the tree structure. In particular, to minimize the total location management cost, a location caching generation approach is proposed to calculate the optimal caching nodes. Extensive experiments have been conducted to verify the efficiency of our proposed strategy.