Efficient Monitoring of Moving Mobile Device Range Queries using Dynamic Safe Regions

Abstract

As the number of mobile devices is experiencing an explosive growth, mobile query processing has become an important application of mobile devices. One of the most frequently used mobile queries is range queries - retrieving surrounding objects of interest. As mobile devices are moving, these range queries are literally moving range queries. The main problem of processing mobile moving range queries is how to know when the surrounding objects of interest are no longer relevant (and the previously distant objects of interest have become relevant) since the mobile device has already moved to a new location. Past researches have proposed the use of safe region - an area where the set of objects of interest to the mobile device does not change. However, when the query leaves the safe region, the mobile device has to reprocess the query. Knowing when and where the mobile device will leave a safe region is widely known as a difficult problem. To solve this problem, we propose two novel methods: (i) efficient construction of the safe region by using only two objects closest to the border of the moving mobile device, and (ii) periodic monitoring the position of the mobile device. Our evaluation shows that our method enlarges the safe region compared with previous methods, giving the mobile device a wider range to roam, and therefore, reducing computation and communication costs.