# An Energy Efficient Routing Approach for IoT Enabled Underwater WSNs in Smart Cities
## 4 Results and Discussion
### Performance Evaluation
#### 4.1.2 U-(ACH)\({}^{2}\)  
with Four Sinks at Water Surface  
In our simulations, N = 225 sensor nodes are arbitrarily placed in a 500 m \(\times\) 500 m \(\times\) 500 m 3-D region and 4 sinks are positioned at the top of the water surface as shown in Figure 8. The sensor node and selected CH will send data to the minimum distance sink. The results are obtained from several runs in order to analyze the diversity among results. For each simulation, a very minute variation was found in the results, which were approximately equal to the previous simulation results. The reason behind the variation is the random deployment of sensor nodes. On average, the results were the same for each run. As the dimensions are 500 \(\times\) 500 \(\times\) 500, which is a small region for which 225 nodes are enough to work with. If the considered dimension was 1500 \(\times\) 1500 \(\times\) 1500, then we may have changed the number of nodes from 150 to 500 to examine the energy consumption of the overall network. We have considered 1000 rounds and, for each round, these nodes perform their desired activity. In the future, we will consider the expanded network region in order to observe the stability period of a network.  
\begin{table}
\begin{tabular}{l l l l l} \hline \hline  & **TEEN-(ACH)\({}^{2}\)** & **DEEC-(ACH)\({}^{2}\)** & **SEP-(ACH)\({}^{2}\)** & **LEACH-(ACH)\({}^{2}\)** \\ \hline No. of dead nodes & high & less & high & high \\ No. of packets sent to BS & min & max & min & min \\ No. of packets dropped & less & high & high & high \\ No. of packets received & min & max & min & min \\ \hline \hline \end{tabular}
\end{table}
Table 3: Scenario-I: Performance of proposed schemes.  
Figure 8: U-(ACH)\({}^{2}\) with Four Sinks at Water Surface.  
In Figure 9, almost all of the nodes of DBR and EEDBR died due to multiple forwarding. DEEC-(ACH)\({}^{2}\), SEP-(ACH)\({}^{2}\), TEEN-(ACH)\({}^{2}\), and LEACH-(ACH)\({}^{2}\) perform well in unstability period. In LEACH-(ACH)\({}^{2}\), energy dissipation is uniform, hence a minimum number of nodes die in network lifetime.  
In Figure 10, DBR and EEDBR nodes send data to BS hop by hop. After a few rounds, nodes start dying, and few nodes cannot find a neighbor to forward data, which results in a limited number of packets conveyed to BS. LEACH-(ACH)\({}^{2}\) achieves the best results in this network model.  
By comparing with other protocols, LEACH-(ACH)\({}^{2}\) sends maximum packets to sink, hence, the packet dropped ratio is higher. In case of TEEN-(ACH)\({}^{2}\), packets are sent to BS according to the threshold value, fewer packets are forwarded to BS; hence, less number of packets are dropped, as shown in Figure 11.  
Figure 10: Number of Packets Sent to BS.  
Figure 9: Number of Dead Nodes.  
In Figure 12, the number of packets received by each protocol are in the following order, LEACH\(-(ACH)^{2}>\) DEEC-\((ACH)^{2}>\) SEP\(-(ACH)^{2}>\) DBR \(>\) TEEN\(-(ACH)^{2}>\) EEDBR.  
The performance of proposed schemes is demonstrated in Table 4 for scenario-II. It can be seen that the LEACH-(ACH)\({}^{2}\) routing protocol outperforms here.  
Figure 11: Number of Packets Dropped.  
Figure 12: Number of Packets Received at BS.