Processing directional continuous range queries for mobile objects on road networks

With the rapid development of wireless communication networks and smart mobile devices, people now can access global positioning system for localization and wireless networks at any time, almost any where. Traditional location-based services for range queries or k-nearest neighbors queries are omnidirectional, in which some query results are probably not interested to a user because they are not on the way to destination. Due to the prevalence of guiding systems and the advances of electronic technologies and wireless communications, most mobile objects on roads move along with the pre-determined paths provided by path planning systems. With the concept of “by the way”, there would be an increasing demand on queries for objects on their traveling paths. In this paper, we define the issue of directional continuous range query for mobile objects on road networks. To address this issue, we not only propose the system architecture of a road network but also provide approaches to determine the safe period in order to efficiently update the query result. We elaborate cases of when to exclude a mobile object from a query result and when to insert a mobile object into a query result. Our experiment results showed that the centralized processing directional continuous range queries has shorter average response time than the distributed one.