## 6 Simulation Setting  
The simulation setting was accomplished using MATLAB. The obtained data were averaged over 50 runs, as the behavior patterns of all the schemes ceased to fluctuate approximately after 50 runs. Both proposed schemes were compared with the RIAR scheme designed in [8], as it also addresses the problem of the void-hole by considering the path from the source to the sink. However, unlike the RIAR scheme, the proposed schemes did not consider the number of hop and distance calculation while constructing routing paths. Moreover, sending data over multiple links towards the destination with the uniqueness of the time for which packets are held by a node differentiates the proposed algorithms from the RIAR framework. The parameters involved in the simulations are described in Table 1.  
The network and communications parameters considered for simulations were almost the same as considered in [4]. The considered network model is a cube the length of a single side of its face is 500 m. Within the network, the deployment of 50 nodes is made in a random manner. This number of nodes is significantly smaller than the usual approach of deploying 225 nodes, so as to ensure that sparse network conditions prevailed. Nodes mutually communicated using acoustic waves to avoid the high attenuation of these waves in water. The sink communicated with sensor nodes using acoustic links and with the data center on the shore using radio links. The amount of power consumed by a single node in data advancement, reception, and idle modes was 2 W, 0.8 W and 10 mW, respectively. A single data packet's size was 50 bytes, while a hello packet's size was 5 bytes. A node could transfer data with a maximum rate of 10 kilobytes per second and possessed a transmission radius of 200 m equally in all directions. For fair evaluation of the performance metrics, the random walk mobility model considered in the RIAR algorithm was also taken into account in the proposed algorithms. In this model, every node randomly chose a direction and moved in that direction with a variable speed of 1 m/s to 5 m/s. \begin{table}
\begin{tabular}{c c} \hline \hline
**Parameter** & **Value** \\ \hline Transmit mode power consumption of a node & 2 W \\ Receive mode power consumption of a node & 0.8 W \\ Idle mode power consumption of a node & 10 mW \\ Deployed sensor nodes’ count & 50 \\ Transmit radius of a node & 200 m \\ Initial energy of a node & 70 J \\ Network’s extent & \(500\times 500\times 500\) \\ Hello packet size & 5 B \\ Data packet size & 50 B \\ Acoustic speed & 1500 m/s \\ Data rate & 10 kbps \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Description of the parameters involved in the simulations. Figure 7 depicts the comparative plot of total energy consumed by each scheme. The backward transmission mechanism to avoid the presence of a hole in ESRVR and Co-ESRVR made them more energy consuming than RIAR. That is, when a void hole existed, these protocols searched for other neighbor nodes to provide connected paths for packets' transfer rather than dropping them. This, in turn, involved more nodes to transfer packets to the water surface. The involvement of more nodes to avoid the loss of information caused energy consumption. As a result, these protocols cost more energy than RIAR, which lacked the backward transmission mechanism. Moreover, initially up to several rounds, all the schemes consumed almost the same amount of energy. This was due to the reason that more nodes were available for data forwarding, and the optimal paths were chosen in all the protocols to transfer information packets. After that, nodes started to die, and the protocols operated according to their designed strategies, which affected the number of involved nodes in information forwarding. As a result, the difference in energy consumption became significant.