Effective management of location dependent continuous queries in mobile environment

Advances in wireless and mobile computing environments allow a mobile user to perform within a wide range of applications. For example, mobile users need to pull data about unfamiliar places or local life styles related to their location. Furthermore, a mobile user may be interested in getting location dependent query results periodically. We propose an algorithm for handling continuous queries in a tree-structure in such a way that the user will get the correct current query result, not the outdated result. In addition our proposed method strives to reduce communication cost. Since data are related to a particular zone, the obvious approach is to replicate fragments of location dependent data (LDD) for each zone. If we follow the approach of replicating fragments of LDD information at each zone, we may not be able to meet the storage requirements in given zones. Therefore, full replication will not work. Hence, we propose an selective replication algorithm in the context of these continuous queries. Our replication algorithm is based on the user´s query pattern. If a particular type of query is frequently requested from a particular zone, we will replicate its corresponding LDD in that zone. We demonstrate that this selective replication strives to balance lookup cost and storage cost using a simulation experiment.