부산대학교 도서관

In today’s internet-of-things (IoT) environment, wireless sensor networks (WSNs) have many advantages, with broad applications in different areas including environmental monitoring, maintaining security, etc. However, high energy depletion may lead to node failures in WSNs. In most WSNs, nodes deplete energy mainly because of the flooding and broadcasting of route-request (RREQ) packets, which is essential for route discovery in WSNs. The present article models wireless sensor networks as software-defined wireless sensor networks (SD-WSNs) where the network is divided into multiple clusters or zones, and each zone is controlled by a software-defined network (SDN) controller. The SDN controller is aware of the topology of each zone, and finds out the optimum energy efficient path from any source to any destination inside the zone. For destinations outside of the zone, the SDN controller of the source zone instructs the source to send a message to all of the peripheral nodes in that zone, so that they can forward the message to the peripheral nodes in other zones, and the process goes on until a destination is found. As far as energy-efficient path selection is concerned, the SDN controller of a zone is aware of the connectivity and residual energy of each node. Therefore, it is capable of discovering an optimum energy efficient path from any source to any destination inside as well as outside of the zone of the source. Accordingly, flow tables in different routers are updated dynamically. The task of route discovery is shifted from individual nodes to controllers, and as a result, the flooding of route-requests is completely eliminated. Software-defined energy aware routing (SD-EAR)also proposes an innovative sleeping strategy where exhausted nodes are allowed to go to sleep through a sleep request—sleep grant mechanism. All of these result in huge energy savings in SD-WSN, as shown in the simulation results.