# Energy Efficient Routing Protocol for an IoT-Based WSN System to Detect Forest Fires
## 3 Proposed Model
### Steady-State Phase  
The Steady-State phase consists of multiple frames, each of which is divided into a number of slots. Each slot is allocated to one member node in the cluster. A member can send data only in its own slot. It keeps its radio OFF in all other slots in a frame. At the start of each slot, a CH turns its radio ON for a very short duration called the Verification Period (VP). If the CH does not hear from the slot owner (member node that owns the slot) during the VP, it turns its radio OFF immediately after the VP. If the CH hears from the slot owner during the VP, it keeps its radio ON for the entire duration of the slot. The VP aids in reducing idle listening in CHs. The proposed model uses another parameter called Distance-to-Event (DE) which aids in reducing the transmission of redundant data. The DE (predefined in meters) ensures that only nodes in the proximity of an event report it to their CHs. If a node is more than DE metres away from the event, it will not report the event to its CH. Figure 4 shows how verification periods are arranged in a frame. Figure 5 shows the flowchart of the steady-state phase in the proposed model. Figure 3: Setup Phase in Proposed Model. Figure 4: Verification Periods in a Frame. Figure 5: Steady-State Phase in Proposed Model: (**a**) Functioning of CH and (**b**) Functioning of member node. After gathering information from the source nodes, the CH forwards the aggregated data to its upstream CH or the BS (if the CH belongs to one of the clusters in the first row in the network architecture). After a predefined number of frames, the next round begins. In the setup phase of the first round, all sensor nodes send information messages (SN\({}_{\text{inf}}\)) to the BS. However, in the setup phase of all other rounds, CHs send information messages (CH\({}_{\text{inf}}\)) to the BS. This CH\({}_{\text{inf}}\) message contains the following information for all the members in the cluster (including the CH itself) - SN\({}_{\text{id}}\) and SN\({}_{\text{ne}}\). Based on this information, the BS can decide whether the current CH can continue to function as the CH of the cluster or whether a new node should be appointed as the CH. A new node is appointed as the CH when the residual energy of the current CH is less than the threshold energy. As member nodes are not directly involved in sending information messages, a significant amount of energy is saved in the setup phase of all other rounds. Algorithm 2 shows the steps in the steady-state phase of the proposed model. Figure 6 shows the functioning of the BS in a complete round. Figure 7 represents a scenario to show the real-time application of the proposed model. In the given scenario, a fire breakout is detected by SN-41 in CL-9. The node sends the information to CH-40, and CH-40 communicates the message to the BS via CH-27 and CH-12. The BS sends the information to the IoT Cloud, which is then immediately sent to the local fire station. The path of data transmission is shown in a red dotted line from CH-40 to the BS and a red solid line from the BS to the local fire station.