sor node 1 Sensor node 2 Sensor node n (Data Plane) Downloaded: 4/15/2022 9:44:49 AM Nova Southeastern University IP Address: 137.52.76.29 Software-Defined Networking Paradigm in Wireless Sensor Networks Figure 2. A generic block diagram for SDN based wireless sensor node Rules Action Statistic Radio unit Source=nodex Forward Dist=nodey Power unit In-network Sensing unit Traffic generation processing the control layer. Abstract layer provides an interface to interact with control layer via southbound interface. At this layer, each sensor nodes can have some important functionality and resources to sense the physical phenomenon, process the sensed data and forward it from one node to the another sensor node. However, these devices do not decide what to do. Decision making part of these devices is done at the control layer and passes it through southbound interface. Control Layer: This layer is a very significant layer in the SDWSN architecture as it performs all decision making functionalities. The main responsible of this layer is to formulate the flow rules, mapping and programming interface with both south bound and north bound interface. In the literature different approaches are proposed for the implementation of this layer. Generally these approaches are categorized as centralized, distributed and hybrid. In centralized controller approach, a single controller is used which controls the entire WSN network. This approach suffers from reliability and scalability issues. However, distributed controller approach overcome these issues and incorporated multiple controllers that are spatially distributed. In (Oliveira, 2014), distributed multiple controllers are used and these controllers are serially attached with sensor nodes and the sink node. Similarly, the authors in (Tsou, 2012) proposed a message exchange protocol called SDNi for message exchange between different interfaces in the multiple distributed controller environments. In the hybrid controller approach, controllers are implemented Downloaded: 4/15/20