Approximate static and continuous range search in mobile navigation

Spatial range search is to find interest objects within a given radius. This type of query is common in a mobile environment as mobile users are able to find surrounding interest objects. Traditionally, a range search query will return all objects within a given radius. However, in many circumstances, having all objects is not necessary, especially when there are already enough objects closer to the query point. Also in other circumstance, expanding the radius may give users better results, especially when there are a lot of objects just outside the search boundary. Therefore, in this paper, we focus on approximate range search, where the query results are approximate, rather than exact. We propose approximate static range search (ARS). Using ARS, we are able to deliver a better performance, yet low false hit and reasonable false miss. We also extend ARS in the context of continuous query setting, in which the query moves. This is particularly important in mobile navigation as a mobile user who invokes the query moves. In continuous range search, the aim is to find split points; the locations where the query results will be updated. We propose two methods for approximate continuous range search (ACRS), namely (i) minimizing range search, and (ii) minimizing split points. Our performance evaluation which compares our methods with the traditional continuous range search shows that our methods reduce number of split points considerably, and hence improving overall performance.