Research On Range Query Basedon Constraint Of Directional Relation Algorithm In Road Network

With the rapid development of wireless communication, GPS location,computer technology and other technologies,as well as the great popularization of numerous of wireless hand-held and in-car devices which have positioning function,especially a wide range of applications of the rising taxi software in the domestic,location-based services have become a promising industry,which getting more attention.Among all location-based services,continuously monitoring the moving objects in road network is a typical demand,for example,the practical problem that continuously searching all taxis which 5km distance from the current position and so on.However most of the current moving object range queries are concentrated on assuming the moving objects moving freely in the Euclidean space and judge whether the object meets the query criteria by Euclidean distance.But these methods just service some certain areas and the majority of users and moving objects are limited by road network. Therefor measuring the distance between the users and moving objects by the network distance is more reasonable.Firstly,based on the latest research results in the existing moving objects indexing and query processing techniques and so on,the study focused on moving objects in road network containing two-way streets and one-way streets continuously range query processing problem.In view of the range query of the continuously updating moving objects and query point proposing the incremental range query based on constraint of directional relation algorithm.This algorithm speeds up the range query speed by filtering out some invalid streets which in the opposite direction of query point.Secondly,based on the CDR-IRQ algorithm, this paper proposes a group range query based on constraint of directional relation algorithm for the characteristic that a lot of query results have a correlation on the same route.This algorithm takes the route for the unit group so that the query points on the same route can share the implementation process of the range query algorithm which can reduce the query recalculation.Finally,experiments are carried out to contrast and analyze.The experimental results show that the CDR-IRQ algorithm is better while moving objects are more evenly distributed in the edge of the road network. On the other hand,the CDR-GRQ algorithm is better while moving objects are more concentrated in the edge of the road network.At last both of these algorithms are better than the original algorithm which expanding blindly during the incremental range query.