PBQ: A priority-based query processing algorithm in opportunistic wireless sensor network

Opportunistic wireless sensor network is a kind of opportunistic network that consists of nodes with sensing capabilities and actively or passively adopts the form of opportunistic transmissions. Due to the lack of stable end-to-end links and query-supporting infrastructures such as clustering or routing trees, the query processing in opportunistic wireless sensor networks is a challenging problem. In this paper, we propose a priority-based algorithm called PBQ for query processing in opportunistic wireless sensor network. Through the user-defined query priorities, the proposed algorithm properly selects the relay nodes and controls the forwarding of the messages. Meanwhile, the query priorities are adjusted dynamically so that the query results could be forwarded back to the query requester quickly and the residual query request messages could be cleaned up from the network, saving lots of unnecessary transmissions. Simulating results show that PBQ improves the overall utility of query processing. It could effectively improve the success rate of queries, and reduces the cost and delay of query processing in opportunistic wireless sensor networks.