# REERP: A Region-Based Energy-Efficient Routing Protocol for IoT Wireless Sensor Networks
## 3 Proposed System Model
### REERP: Proposed Routing Protocol for Multi-Hop Transmission  
The system model was discussed in the previous subsection. There are a total of \(n\) sensor nodes that are equally dispersed in _region \(\times\) s\({}^{2}\)_. The entire network is subdivided into four regions in the proposed network topology. The following are the predictions made:  
1. Nodes are designed to remain stable after deployment, but every sensor node is fitted with a GPS to aid in determining the location of the node. 2. Although all sensor nodes have identical processing and communication capacities, their initial energy requirements vary (heterogeneous network). 3. The base station, which is absent from the network as seen in Figure 2, is constantly required to acquire data from the sensors. 4. Sensor nodes are deployed and then left unattended, making battery replacement impossible. 5. There are no energy, computing, or memory limitations in the network, which has only a single base station from outside the network. 6. Data sent from node a to node b use the same amount of energy as data sent from node b to node a, since all wireless connections are symmetric. In the approach suggested, as presented in Figure 2, multi-hop transmission is deployed to extract the details of the nodes' locations, which is essential to evaluate which transmission method all the nodes should investigate. The network is categorized into four regions based on the locations of every sensor node; all nodes are given a distinct ID (Identification) and fitted with a global positioning system (GPS), which aids in determining which region they should correspond to. As a result of the proximity of the base station to the sensor nodes in the first region, direct communication will be more effective while using less energy versus multi-hop communication. Therefore, to transfer their data, the nodes in this area will rely on a direct connection. Because of their distance from the base station, nodes in the second field rely on multi-hop transmission. These nodes transmit them to the gateway with their data, which then forwards them to the base station. Since there are several sensors in regions 2 and 3 and they are far from the base station, aggregating these nodes and using hierarchical clustering routing is the most effective technique to minimize energy utilization in both regions. For the purpose of aggregating cluster data and transmitting it to the BS, cluster members from all regions designate a CH. In the proposed method, a ratio is used between the remaining energy of the sensor node and the average energy of the network to determine the CH. To overcome this problem and save energy, we rely on the calculation of the baseline energy that each sensor must utilize for each round; this enables us to calculate the energy intensity of every SN during each round. This calculation is based on our estimate of the desired value of the network lifetime. The functioning of the suggested system model is shown in the flowchart depicted in Figure 3. In this, first, we will check for all the nodes in the different regions, then calculate the distance for all the regions. If maximum distance > distance, then we add all the nodes to the BS; in case maximum distance \(\leq\) distance in region 1, then we add all the nodes in region 2; and if maximum distance == distance, then we add the nodes in region 3, while otherwise, we add all the nodes in region 4. There are three steps in the proposed model:  
* **First Stage:** Every node forwards an ID table to the base station when all sensors have been deployed. The address, remaining energy levels, and travel times to the gateway and BS are listed in the ID table. * **Setup Stage:** This separates the network into four regions on BS, as depicted in Figure 2, by taking into account each node's address. Nonclustered regions are classified as regions 1 and 2. While nodes in Region 2 interact with the Gateway, which combines the data and sends them to the base station, nodes in Region 1 broadcast their data directly to the BS.