## 4 Proposed Network Model
### Network Architecture Designing  
The network architecture is designed as depicted in the scenario shown in Figure 4, and it is configured according to the assumptions mentioned above (Section 4.2). The proposed protocol is implemented in the sink node gateway to select an optimum cluster head dynamically. Moreover, the location of the nodes, including the SN, is configured when the network is initialized and the network nodes are stationary. Therefore, when the SN elects the optimum CH, it informs all nodes about the location of the current CH. However, to scale the proposed network, only the new cluster is added (with its corresponding SN) in the specified direction to the nearest cluster edge, and the first configuration is performed manually. Furthermore, the network topology list for each cluster in the SN is updated dynamically when dead nodes are deleted during the dynamic re-clustering process. The uniform deployment was essentially adopted to locate the SN s at the center of each cluster, to enable all the regular nodes to communicate to it directly and, in the same way, the BS was located in the center of the SN s for the same reason. Additionally, the area of each cluster is in an appropriate size to enable all regular nodes to communicate with one another directly and effectively. Furthermore, the adopted periodic election policy keeping the view of uniform deployment of nodes until close to the end of the network's life. The proposed algorithm in Section 5 will explain further how to implement the proposed network. Proposed Lightness Architecture and Protocol Efficiency  
The philosophy for choosing an appropriate network architecture and its data transmission model has a major impact on the network lightness and efficiency of the proposed protocol. According to the recommendations of a survey conducted in [32], it becomes clear that the lightest architecture among different architectures is the hybrid architecture, as it acquires the advantages of the distributed and centralized approaches while exceeding their particular limitations. Therefore, the researchers worked to reduce the number of nodes in each cluster to overcome the issue of the energy bottleneck region around the sink node. Similarly, the acceptable number of sink nodes is increased to obtain the advantages of the distributed approach. On the other hand, when the number of clusters is small, intra-cluster distance is becoming too far and it will cause extra power consumption for data transmission and data loss. In addition, an overlarge number of clusters leads to redundancy when several cluster heads send the same data to the base station (BS) [33]. Experiments should be performed to determine the optimal number of sink nodes and the optimal number of regular sensors in each cluster according to the energy consumption of the whole network lifetime. A sink node of each cluster is located at the center of the cluster to aggregate data from all the nodes effectively. Furthermore, to make the network lightweight and less power consuming, to improve the data transmission process, and to adjusting the deployment to be easy, a hybrid-clustering model is adopted. A single-hop clustering model is used in the cluster core (between all the sensor nodes and the cluster head). However, its drawback appears when the network size grows in ways such as consuming much more power and increasing the dropping ratio due to the large distances among nodes. Thus, a single-hop method is adopted at the core of the cluster, where nodes are a small size and have a short distance between one another. Conversely, to achieve connectivity and scalability, which the single-hop clustering model does not achieve, the multi-hop clustering model is used in the cluster edge (between the CH and BS via the SN).