Continuous Nearest Neighbor Query Research Of Mobile Object In Mobile Environment

With the rapid development of technology, global positioning system and communication technology can record the positions of moving objects. The continuous movement of moving objects results in new challenges to database technology, and moving objects database appeared. In moving objects database, nearest neighbor queries attract much attention. However, the past research mostly focuses on the nearest neighbor queries in static environment, and how to expand it to mobile environment becomes emphasis and difficulty.This paper studies on nearest neighbor queries in a mobile environment. The algorithms based on TPR-tree and split time are introduced, and are expanded to k nearest neighbor queries and continuous nearest neighbor queries in a mobile environment.Firstly, the indexing techniques are discussed and TPR- tree is adopted.The structure is suitable for future nearest neighbor queries and can improve the quality and efficiency of the queries.Secondly, the characters of nearest neighbor queries are analyzed. The split time is introduced and the detailed computing formulas are presented. For the distance computing, the approximate algorithm is ameliorated and an accurate algorithm is presented.Thirdly, the split time is used in the nearest neighbor queries algorithms. The algorithms traverse TPR-tree in a depth-first and width- first manner to find the nearest neighbor by pruning technique. The algorithms are suitable for the nearest neighbor queries in high dimension and have strong expansibility.At last, the algorithms are expanded to k continuous nearest neighbor queries in a mobile environment. Experiments are done to validate the feasibility and validity of the algorithms.