%0 Journal Article
%T Location-Dependent Continuous Query Processing Using Hierarchical Location Databases<br>基于层次组织位置数据库的连续位置相关查询处理
%A LI Guo-Hui
%A <br>李国徽
%J 计算机科学
%D 2003
%I 
%X With the advances in mobile computing and mobile communication technology, there comes a kind of novel applications in which the locations of moving objects are maintained and processed. In existing literatures, a data model called moving objects sptio-temporal (MOST)1,2] is proposed and a new location record is generated when the distance between the actual location and the database location of a moving object exceeds a pre-defined distance threshold. In a mobile computing environment, a user can issue location-dependent continuous queries (LDCQs). To cater for the large number of moving objects in the system, this paper first gives a hierarchical distributed location database model to store the locations of moving objects. Based on the distribution of the location databases for different moving objects, this paper then proposes a method to determine the processing site for a location-dependent query. When a LDCQ is processed, a set of tuples (O. begin, end) is provided indicating that object O satisfies the condition presented in the LDCQ from time begin to end. In the existing literatures, when there is a location update generation, the related LDCQ is re-processed and the answering tuples are re-transmitted via the wireless channel. This location-update-based LDCQ processing method has its disadvantages: it has much CPU calculation cost and imposes a high overhead in the wireless bandwidth which is very undesirable in a wirelss environment. Based on the maximal speed of a moving object, this paper presents a deferred LDCQ evaluation strategy.
%K Hierarchical location database
%K Location update generation
%K Location-dependent queries
%K Continuous queries
%K Location management for moving objects<br>数据库管理系统
%K 数据模型
%K 层次组织位置数据库
%K 数据查询
%K 数据处理
%U http://www.alljournals.cn/get_abstract_url.aspx?pcid=5B3AB970F71A803DEACDC0559115BFCF0A068CD97DD29835&cid=8240383F08CE46C8B05036380D75B607&jid=64A12D73428C8B8DBFB978D04DFEB3C1&aid=26999C936AEEC0AF&yid=D43C4A19B2EE3C0A&vid=340AC2BF8E7AB4FD&iid=E158A972A605785F&sid=CD775AE9DDBD7B53&eid=7E8E8B150580E4AB&journal_id=1002-137X&journal_name=计算机科学&referenced_num=0&reference_num=6