MQry: Elastic Validity Region for Querying Mobile Point-of-Interests in Infrastructure-Less Networks

A region-based querying has been widely used to update the freshness of query result and reduce the query traffic in diverse wireless networks. Most prior querying approaches implicitly assume infrastructure-based networks but we need to relax this assumption by considering limited coverage or even unavailability of the network. In this paper, we propose an elastic validity region and its corresponding query operation, called MQry, in an infrastructure-less network with mobile point-of-interests (POIs). Due to the mobility of nodes and POIs, it is challenging how to efficiently build and update a validity region. Each query replying node that contributes in building an initial validity region judiciously switches its monitor operation on the queried POI. The query issuing node adjusts the current validity region to reduce the number of redundant queries without hurting the freshness of queried result. The query operations of both query issuing and replying nodes are depicted using finite state machines for clarity. We conduct extensive simulation experiments using the OMNeT++ for performance evaluation and comparison with four existing schemes. The simulation results show that the MQry can adaptively change the size of validity region and be a viable querying approach in infrastructure-less networks.