# Forest Fire Detection Using New Routing Protocol
## 5 Methodology of LAR-Based Reliable Routing Protocol (LARRR)
### Finding the Route  
The route discovery process for building routes is initiated once the node generates a data packet and needs to send. In this case, the node should determine the request zone with respect to the place information obtainable within its location table. Subsequently, the node will be able to send the RREQM to other nodes within the network. In the proposed LARRR protocol, the RREQM will include the information illustrated in Figure 6.  
The RREQM is transmitted to nodes that are located within the coverage zone of the sender. Each node receives this RREQM, adds its address to the \"Route\" field, and will forward it to other nodes if they are located in the request zone. However, to those nodes that receive the RREQM before (i.e., same packet ID) or are located outside the request zone, they will discard the RREQM. Afterward, the RREQM moves through intermediate nodes until reaches the \(D\) node. As soon as the \(D\) node acquires several RREQMs from different nodes, it generates a RREPM for every RREQM. Figure 7 shows the information of the RREPM. The nodes that exist in the coverage area of the \(D\) node will receive the RREPM. If they find their address in the \"Route\" field, they will update the content of \"Route temperature\" and \"Route busyness\" by adding their information and forwarding the RREPM. Then, the RREPM will move through the intermediate nodes until reaching the \(S\) node. It can be observed that the earlier process may take some time (i.e., not immediately). Consequently, there is a period of time named the Time Out Period (TOP). In other words, the \(D\) node must wait and then make a decision for the next process. Figure 6: The contents of RREQM. Figure 7: The contents of RREPM. However, in the case where no routes exist to the \(D\) node after the TOP or the \(S\) node does not receive the RREPM, the \(S\) node will receive a route error message, and it creates a new route discovery process to search for other routes to send another data packet to the \(D\) node. Thus, the data packet of the broken path should be removed if the TOP is elapsed. In other words, the RREQM, RREPM, and data packet should all arrive through the TOP. Consequently, the node should select the best route in order to obtain a better performance of the network with respect to receiving as many packets as possible, reduce the routing overhead, reduce the delay, and reduce the energy consumption. In the LARRR protocol, routes that include nodes with high temperatures should be chosen because these nodes will fail shortly due to the fire. Therefore, consuming the energy of these nodes before they totally fail is considered a cost-efficient method for the purpose of saving other nodes' energy and then increasing the network's lifetime. However, if a node with high temperature is constantly selected, the route of that node will be very congested. Accordingly, the proposed LARRR protocol is based on three criteria for obtaining a fitness value to select the best route, where each route is set with a fitness value to evaluate the quality of routes and then to determine the best route. The routes in the LARRR protocol consider the route length, node's temperature, and the packets number in the node's buffer. The fitness value of the LARRR protocol can be obtained as follows:  
\[fitVal=RL+(1-Max(Temp))+Max(B) \tag{1}\]  
where \(RL\) (_Route Length_) indicates the hops number from the \(S\) to the \(D\), _Max (Temp)_ indicates the highest temperature of a node (i.e., 130 \({}^{\circ}\)C), while _Max (B)_ indicates the maximum number of existing packets within node buffers. It is worth mentioning that a node should select the best route based on obtaining the lowest fitness value. Furthermore, the transmission of a RREQM should be stopped after a period of time for the purpose of reducing the routing overhead of the proposed LARRR protocol.