移动计算系统中位置数据库组织

移动计算系统中移动用户的位置信息管理是非常重要的问题。目前,商用移动通信系统采用两层结构组织的位置数据库管理移动用户位置信息。由于其可扩展性较差,人们提出把位置数据库组织成树状的层次结构来管理移动用户位置信息。不同移动单元的位置数据库组织对移动用户位置管理代价有很大影响,本文考虑到不同移动单元中移动用户的移动模式特点,基于集合覆盖理论,设计实现了一个启发算法来对位置数据库进行组织,减少了位置管理的代价。实验显示,该位置数据库聚簇显著减少了位置更新的代价。

Location Database Organization in Mobile Computing Systems

An important issue in the design of a mobile computing system is how to manage the location information of mobile clients. In the existing commercial cellular mobile computing systems, a two-tier architecture is adopted. However, the architecture is not scalable. In literatures, a hierarchical database structure is proposed in which the location information of mobile clients within a cell is managed by the location database responsible for the cell. The location databases of different cells are organized into a tree-like structure to facilitate the search of mobile clients. This architecture can distribute the workload amongst the location databases in the system. The location database organization has much impact on the total location management cost.In this paper, considering the mobility patterns of mobile clients in different cells, we give a heuristic algorithm to cluster the location databases with the objective to reduce the location management cost. A set of experiments are designed to evaluate the performance. The comparison shows that our location database clustering method can result in location update cost reduction.