Investigation of querying techniques for federated sensor networks

Federated sensor networks (FSNs) connect and combine several partitioned wireless sensor networks (WSNs) to extend the scope of WSNs to larger scale geographical areas. The federated and sparsely/intermittently connected nature of FSNs introduce several challenges for deploying middleware services such as routing, querying, tracking, time synchronization. In this paper, we investigate the challenges for deploying a querying service on FSNs. We review several querying protocols proposed in the WSNs literature and identify the applicability and shortcomings of these protocols for FSNs. Based on our investigation, we suggest open research directions for building an efficient querying service for FSNs.