Continuous Location Dependent Queries in Mobile Wireless Sensor Networks

Query processing in mobile Wireless Sensor Networks (WSNs) is still a challenging problem because sensor mobility causes frequent changes of network topology. In this paper, we study the problem of processing Continuous Location Dependent Query (CLDQ) that retrieves the sampling data of the sensors within a specific area (i.e. query area) around a mobile sensor. Existing query processing approaches can not efficiently process CLDQs with continuously moving query areas. We propose scalable techniques to process CLDQs efficiently and accurately, including a dissemination approach, a Contention-based Distance-aware Message Scheduling scheme, in which each stationary sensor’s data transmissions are smartly scheduled according to its distance to the mobile sensor, and an optimization scheme for continuous processing of CLDQs. Extensive experiments indicate that our techniques demonstrate better efficiency of processing CLDQs over state-of-the-art techniques while achieving high accuracy and short query latency under various network settings.