# An Energy Efficient Routing Approach for IoT Enabled Underwater WSNs in Smart Cities
## 4 Results and Discussion
### Performance Evaluation
#### 4.1.3 U-(ACH)\({}^{2}\) with One Sink at Water Surface and One Underwater  
In our simulations, N = 225 sensor nodes are arbitrarily placed in a 500 m \(\times\) 500 m \(\times\) 500 m 3-D region, one of the sinks is placed in the middle of the water surface, and one is at top of the network. Sensor nodes having a depth greater than selected CHs and selected CHs will forward data to the nearer sink. CHs that are in the bottom of the network will forward data towards the sink, which is present in the middle of the network, as demonstrated in Figure 13. Likewise, previous two scenarios, here also the results were obtained from several runs 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. Due to multi-hop data forwarding, a maximum several nodes died in DBR and EEDBR, as shown in Figure 14. SEP-\((ACH)^{2}\) and DEEC-\((ACH)^{2}\) are heterogeneous routing protocols, thus nodes remain alive for a longer period. In TEEN-\((ACH)^{2}\), less number of nodes die because nodes transmit data based on a threshold value. \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 & high & high & less \\ No. of packets sent to BS & min & min & min & max \\ No. of packets dropped & less & high & high & high \\ No. of packets received & min & min & min & max \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Scenario-II: Performance of proposed schemes. Figure 13: U-(ACH)\({}^{2}\) with One Sink at Water Surface and One Underwater. In Figure 15, data packets sent to sink are in order DEEC-\((ACH)^{2}>\) SEP-\((ACH)^{2}>\) TEEN-\((ACH)^{2}>\) DBR \(>\) EEDBR \(>\) LEACH-\((ACH)^{2}\), which is directly proportional to the remaining energy of a network. Figure 16 shows that the packet dropped is directly proportional to the packet sent to BS. In this case, the TEEN-\((ACH)^{2}\) protocols perform much better than all other mentioned protocols. Figure 14: Number of Dead Nodes. Figure 15: Number of Packets Sent to BS. According to Figure 17, packets received at the sink are in order DEEC\(-(ACH)^{2}>\) SEP\(-(ACH)^{2}>\) LEACH\(-(ACH)^{2}>\) others. Less energy is consumed to transmit the packet to sink, as two sinks are deployed at top and underwater. The nodes having a depth greater than underwater sink will send data to it while others send data to the top sink. The performance of proposed schemes is demonstrated in Table 5 for scenario-III. It can be seen that, concerning other routing protocols, DEEC-(ACH)\({}^{2}\) routing protocol is still showing better performance than others. Figure 16: Number of Packets Dropped. Figure 17: Number of Packets Received at BS. In order to conduct the simulation, for each scenario, we have considered 1000 rounds and for each round, we have assumed the number of nodes 'N' as 225, as shown in the proposed study. We have considered 1000 rounds and for each round, these nodes perform their desired activity. According to the results section, Table 6 is drawn, which shows the comparison of the number of discussed protocols. Any organization concerning routing protocols for transfer of data underwater can achieve their desired performance by considering any of the mentioned cases, i.e., deployment of sink nodes. Underwater routing protocols are performing varyingly in the considered cases. With respect to the existing protocols, the proposed protocols perform better. The trade-off is reflected in the performance of every considered protocol. However, according to the study, the DEEC-(ACH)\({}^{2}\) protocol performs outclass among the number of mentioned protocols and, in the case where only one sink node is placed underwater and the other is implanted at the water surface.