## 5 Simulation Settings  
MATLAB is used to perform the simulations. A 3D region of each side of 500 m is considered for the deployment of 225 nodes [22], which is random. The static surface sinks are installed at the surface of the water. A depth sensor is attached with each node, which is used to measure the node's depth from the water surface. The communication range for each sink and node is 100 m. The commercial LinkQuest UWM1000 modem data rate of 10 kbps is used [49]. Each node transmits the packet having the size of 50 bytes. The MAC protocol as in [PERSON] et al. [10,50] is used, which advances packets are on the free channel and drops them when congestion occurs even after attempting predefined multiple times. Energy of 10 J energy is assigned to every node, except in the proposed schemes that assign more energy to low depth nodes to avoid their early death. The sensor nodes consume 2 W, 0.1 W, and 10 mW power in transmit, receive and idle mode, respectively. In Table 3, simulation parameters are shown. We select the DBR [27], Co-DBR and ODBR [27] to compare it with proposed schemes. The reason is that these protocols consider the lowest depth for data forwarding and they are also localization-free protocols just like the proposed protocols. The total residual energy for each protocol is depicted in Figure 12. The residual energy of DNAR and Co-DNAR is greater than the other schemes due to suppression of greedy forwarding in the latter in which a node forwards data to every possible route except to the one from which it receives the data. This causes excessive energy load on nodes and they consume energy rapidly. In addition, DNAR and Co-DNAR assign more energy to low depth nodes so more energy is preserved with these protocols. DBR preserves more energy than Co-DBR due to the cooperation of relays in the latter, which consumes more energy. At the same time, ODBR preserves less energy than DBR as the former assigns less energy to high depth nodes than DBR which assigns equal energy to all nodes. \begin{table}
\begin{tabular}{l l} \hline \hline
**Operations** & **Values** \\ \hline Frequency & 30 kHz \\ Packet size & 50 bytes \\ Initial energy & 10 J \\ Network depth & 500 m \\ Network width & 500 m \\ Network height & 500 m \\ Depth threshold & 60 m \\ Receiving power & 0.1 W \\ Transmission range & 100 m \\ Transmission power & 2.0 W \\ Total rounds & 1400 \\ Total sink nodes & 4 \\ The speed of sound in water & 1500 m/s \\ Total number of sensor nodes & 225 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Simulation parameters. In Figure 13, initially, the PDR of DBR is greater than DNAR, because a greedy method is used in the data forwarding in DBR. In this method, the same packet is transmitted by more than one forwarder. Later on, the nodes that are close to the sinks become dead quickly, as such nodes have more packets load. Thus, PDR of DBR falls in subsequent rounds and becomes the minimum. In the DNAR protocol, the source node checks the condition of the channel when it has a packet to be transmitted. Therefore, it excludes all noisy links while forwarding the data packets. The avoiding of a noisy channel assures high packet delivery in DNAR. The PDR Co-DBR is greater than the rest of the schemes as it involves cooperative routing; which increases packets delivery to the sea surface, and assigns more energy to low depth nodes so they remain active for a long time to deliver packets. In addition, the involvement of minor sink nodes further adds to packets delivery in Co-DNAR. Co-DBR has initially greater PDR than ODBR, DBR, and DNAR due to cooperative routing. However, redundant data transmission in combination with cooperative routing in Co-DBR puts a high load on low depth nodes. So, these nodes dying is what affects packet delivery to the sea surface. As a result, the PDR of Co-DBR falls later on. The redundant packets transfer in a greedy manner in ODBR makes its PDR greater than DNAR. Figure 12. Total residual energy. Figure 13. Total packets received at the sink surface.