Querying sensor networks using ad hoc mobile devices: A two-layer networking approach

—An interplay between mobile devices and static sensor nodes is envisioned in the near future. This will enable a heterogeneous design space that can offset the stringent resource and power constraints encountered in traditional static sensor networks by taking advantage of the more powerful mobile devices. We present a systematic framework for end-to-end query processing, using a two-layer architecture that consists of mobile devices at the upper layer and static sensor nodes at the bottom layer. The framework employs a " PULL " query model that contains staged operations including query generation, query routing, query injection, and query result routing. Each of these stages of query processing is discussed with an emphasis on techniques for energy-efficient query injection and query result routing with location-ignorant sensor nodes. The techniques leverage the mobility and transmission flexibility of mobile objects at the upper layer. Numeric and simulation results are provided to support the proposed methods.