A Continuous Query Processing Method in Broadcast Environments

Abstract

To provide efficient location based services, various methods that process a query in broadcast environments have been proposed. In broadcast environments, a server broadcasts data periodically and a client receives the data and processes a query. Recently, several methods to process a continuous query for mobile objects in broadcast environments have been proposed. However, since clients process the query using the index of the past data that is already built before the broadcast in the methods, the accuracy of the query result is low. They also do not consider the mobility of the objects during the broadcast cycle. Therefore, the methods are not suitable for a continuous query over the dynamically moving objects. In this paper, we propose a new indexing method for a continuous query in broadcast environments. The proposed method uses the vector attributes of objects to reduce the error of the result during the broadcast cycle. To process the continuous query, clients receive the all data intersected with additional regions containing the objects affecting the query in the broadcast cycle as well as the query region. The proposed method also minimizes the additional search regions to save the costs of receiving the data and computing the query. To show the superiority of the proposed method, we evaluate the performance from various perspectives.