# Enhanced Three Layer Hybrid Clustering Mechanism for Energy Efficient Routing in IoT
## 5 Performance Evaluation  
Simulation parameters are given in Table 1. Here we evaluate the simulation results of the proposed technique. Simulations are conducted using MATLAB/Simulink. One hundred nodes of the same initial energy are randomly deployed over a network of 100 m * 100 m. The Sink node is placed outside the covered area at (50 m, 175 m) in the 2D network. The main goal of the proposed technique is to prolong the network life time by avoiding retransmissions and heavy control packet exchange between sensor nodes every round. Figure 4 shows the network lifetime of the proposed technique compared with other recent schemes. The shorter network lifetime of HHCA technique is due to the heavy control packet exchange between sensor nodes after every round for selection of efficient CH at lower layer. HHCA results are improved from the basic clustering technique LEACH and its improved version for three layer clustering routing TL-LEACH scheme, which are fully distributive clustering techniques. The main cause of low performance of LEACH is the inefficiency in procedure of CH selection. TL-LEACH tackled that problem, but since it is a fully distributive approach, it consumes more energy than a hybrid approach. While HHCA outperforms LEACH and TL-LEACH, it still consumes high energy on selection of appropriate forwarders at lower layer. In the proposed scheme, exchanging control packets between sensor nodes is limited to a large extent by defining energy levels that control in a balanced manner the rotation of CH role among the deployed sensor nodes. Results show that sensor node energy lasts for a longer time in the proposed mechanism due to minimizing wasteful operations. Sensor nodes in the proposed scheme start dying at later rounds as compared to other mentioned techniques due to limitation of control packet transmission and reception between sensor nodes over and over after every round. This help in saving energy of sensor nodes and thus prolonging their lifetime. The overhead of the proposed algorithm is that when the batteries of sensor nodes reach to final stage, the graph of alive nodes falls sharply, as can be seen in Figure 4. The reason behind this is that nodes assigned as forwarders in the proposed algorithm do not change their state until their residual energy falls from a certain limit which is comparatively much larger than that of HHCA and other protocols, as explained in Section 4. Once all node batteries in the cluster reach the final stage, they start dying out frequently. In Figure 5, the total number of data packets transmitted and successfully received at base station are shown. The proposed scheme appears to have better result from HHCA, TL-LEACH, and LEACH protocols due to longer network lifetime. The good amount of energy that is used in other schemes during selection of CHs is saved to a large extent in the proposed scheme, and thus nodes remain alive for longer periods of time. This results directly in increasing the total number of successfully delivered data packets from sensor nodes to the base station. As many nodes die out in the network, that probability of data packet drop increases. In the proposed mechanism, sensor nodes remain alive for a longer time and thus the ratio of data packet drop is reduced. \begin{table}
\begin{tabular}{c c} \hline \hline
**Parameters** & **Values** \\ \hline Network area & 100 m \(\times\) 100 m \\ Initial node energy & 2 J \\ Number of sensor nodes & 100 \\ Data packet size & 500 bytes \\ Packet header size & 20 bytes \\ Control packet size & 8 bytes \\ Bandwidth & 1 Mbps \\ \(E_{elc}\) & 50 nJ/bit \\ \(\epsilon_{fs}\) & 10 pl/bit/m\({}^{2}\) \\ \(\epsilon_{mp}\) & 0.0013 pJ/bit/m\({}^{4}\) \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Simulation parameters and their values. Figure 6 shows network lifetime of the proposed scheme with different total energy levels \(TL\), which is defined in Equation (6).