# An Energy Efficient Routing Approach for IoT Enabled Underwater WSNs in Smart Cities
## 4 Results and Discussion
### Performance Evaluation
#### 4.1.1 U-(Ach)\({}^{2}\) with One Sink at Water Surface  
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. 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. The simulation results for the U-(ACH)\({}^{2}\) with one sink at water surface scenario are shown in Figure 3 and discussed below:  
Figure 4 shows the comparison of dead nodes in various routing protocols. In DBR only depth considered so at an earlier stage low depth nodes die because of high data forwarding rate. However, in other routing protocols initially load on the nodes having high residual energy is high, thus resulting in the sharp depletion of nodes. Secondly, there is only one sink in the network, which is deployed at the top, so both nodes and CHs have to transmit data packets towards the top, which requires more energy.  
Figure 3: U-(ACH)\({}^{2}\) with One Sink at Water Surface.  
In Figure 5, DEEC-(ACH)\({}^{2}\) performs well when comparing with other routing protocols. As DEEC-(ACH)\({}^{2}\) is a multilevel heterogeneous routing protocol because of which nodes kept alive for longer duration and, thus, large number of packets are disseminated to the sink. In DBR and EEDBR, each node sends packets through various tracks to the sink that is why results in the maximum number of packets sent. In LEACH-(ACH)\({}^{2}\), all nodes have the same initial energy; hence, nodes will die soon and fewer packets will arrive at the sink. In TEEN-(ACH)\({}^{2}\), packets are transmitted on the basis of the soft and hard threshold, due to which less number of packets will hit the BS.  
Several packets dropped are in direct relation with the number of packets sent to sink, Figure 6, shows that the number of packets dropped is high in DEEC-(ACH)\({}^{2}\), because DEEC-(ACH)\({}^{2}\) sent maximum number of packets. High residual energy is consumed in transmitting data to the sink. DEEC-(ACH)\({}^{2}\) having higher energy will send more packets successfully to sink than others. In DBR  
Figure 4: Number of Dead Nodes.  
Figure 5: Number of Packets Sent to Base Station (BS).  
and EEDBR, packet is forwarded through multiple directions, so the packet received first is considered as received and the rest are dropped.  
In Figure 7, maximum packets are received by DEEC-(ACH)\({}^{2}\) as it sends a large set of packets towards the sink. DBR sends packets to sink in multi-hop fashion, hence more packets received at BS. The rest of the protocols show similar behavior in this scenario.  
The performance of proposed schemes is demonstrated in Table 3 for scenario-I. It can be seen that the DEEC-(ACH)\({}^{2}\) routing protocol outperforms here.  
Figure 6: Number of Packets Dropped.  
Figure 7: Number of Packets Received at BS.