# An Energy Centric Cluster-Based Routing Protocol for Wireless Sensor Networks
## 5 Performance Evaluation
### Discussion  
The reasons for the superior performance in network lifetime of ECCR are justified and summarized as follows.  
* Periodic clustering approach of the existing protocols requires an additional energy consumption of the nodes for broadcasting and receiving a number of control messages in every round. Unlike re-clustering of the protocols, the static clusters of ECCR do not require any control message after the initial clusters formation. Hence, this saves the energy consumption of the nodes in this regard for rest of network operation.
* The cluster head elections of EADUC, HUCL and IEADUC are based on the residual energy of nodes where the average distance among the neighbor nodes has not taken into consideration. Only the residual energy of a node might not be an effective factor to select a cluster head, even though a node with a higher residual energy can sustain as a cluster head for a longer period of time. In these protocols, a node with a higher residual energy as a cluster head does not guarantee the minimum amount of energy consumption during the intra-cluster communication. It may happen due to the higher communication distance between the cluster head and member nodes. Meanwhile, the common cluster head election process of the protocols does not guarantee that only the higher residual-energy-obtained nodes are elected as the cluster heads across the network. Some of the cluster heads might have less residual energy compared to their member nodes due to the biased time \(T\) and cluster formation policies. Thus, the energy consumption among the nodes is not properly balanced, and some nodes may die quickly as a result. In contrast, our proposed cluster-head election technique is based on the ranks of the nodes and considers the residual energy and average distance among member nodes as well. Along with the balancing energy consumption of the nodes, the proposed method saves the energy of the nodes during intra-cluster communication over the network. Moreover, the piggyback and caretaker techniques in cluster-head election reduce a significant number of control messages throughout the network lifetime as in HUCL and IEADUC.
* A shortest route considering only the distance from a cluster head to the BS for data forwarding might cause the packets dropped of aggregated data packets at a certain relay node due to the lack of residual energy of the node to process the data and transmits to the next hop towards the BS, such as in EADUC. Distributing a load of aggregated packets across the network might not only increase the number of hops but also might consume an additional amount of energy of the associated cluster heads in the routes. It impacts on the overall network lifetime, such as in EADC. Instead, our adopted route selection towards the BS constructs a preferable energy-efficient route. It associates the cluster heads with higher ranks. The selection process considers the residual  
Figure 10: Network lifetime.  
energy, number of member nodes, and distance from the BS. The method balances the energy consumption of the cluster heads as well as minimizes the number of average hops, which is more energy efficient in this regard.