# DOW-PR DOlphin and Whale Pods Routing Protocol for Underwater Wireless Sensor Networks (UWSNs)
## 3 Problem Statement  
The WDFAD-DBR protocol abbreviates the priorities of PFNs in designing the holding time of the received packets by considering the accumulative depth differences of the potential forwarding nodes at hops 1 and 2 [3]. WDFAD-DBR does not only consider the depth of the current node, but also the depth of the node at the next expected hop. Therefore, weighting sum of the depth difference i.e., \(H\) is the combination of depth difference \(h\) between the source node and next PFN and the depth difference \(h1\) between the PFN at hop 1 to the next expecting PFN at hop 2. However, WDFAD-DBR does not consider the number of suppressed nodes and number of PFNs of a source node, which consumes a significant amount of receiving energy. The reason behind it arises from the fact that a  
\begin{table}
\begin{tabular}{l l l l l l l l} \hline \hline
**Protocol** & **Delivery** & **Delay** & **Energy** & **Bandwidth** & **Reliability** & **Cost** & **Performance** \\  & **Ratio** & **Efficiency** & **Efficiency** & **Efficiency** & & **Efficiency** & \\ \hline VBF [9] & Low & Low & Fair & Fair & Low & n/a & Low \\ HH-VBF [11] & Fair & Fair & Low & Fair & High & n/a & Fair \\ ESEVBF [20] & High & Low & High & Fair & High & n/a & High \\ FBR [10] & Fair & High & High & Fair & Fair & n/a & High \\ DFR [13] & Fair & Fair & Low & Fair & High & n/a & Fair \\ Mtipath [15] & Fair & Fair & Low & Fair & High & Low & Fair \\ DBR [2] & High & High & Low & Fair & High & Fair & High \\ WDFAD [3] & High & Low & Fair & Fair & High & Fair & High \\ DOW-PR & High & Fair & High & Fair & High & Fair & High \\ Adaptive [7] & High & Fair & Flexible & Flexible & Flexible & n/a & Fair \\ ICRP [19] & Fair & Low & Fair & Fair & Low & High & Low \\ DUCS [17] & Fair & Low & Fair & Fair & Low & High & Low \\ HydroCast [18] & High & High & Fair & Fair & Fair & Fair & High \\ MCCP [10] & Low & Low & High & Fair & Fair & High & Fair \\ H2-DAB [31] & High & Fair & Fair & Fair & Fair & High & Fair \\ \hline \hline \multicolumn{8}{l}{_n/a: not applicable_} \\ \end{tabular}
\end{table}
Table 1: Qualitative Comparison of UWSN protocols.  
large number of PFNs result in receiving the packet as well as the high probability of duplicate packets generated at the first hop and hence excessive transmission energy wasted. The second important reason is that WDFAD-DBR does not consider the hops number for a packet to travel through. In case of a void hole i.e., when the forwarding node does not exist or the existing forwarding node does not have enough energy to communicate, WDFAD-DBR will drop the packet straight away and therefore Packet PDR degraded.The proposed protocol considered the number of suppressed nodes, number of PFNs, and hop count of each potential forwarder as well as the weighting sum of the two hops neighbors. For instance, if considering node S as the source node and nodes A and B are the next hop potential forwarding nodes, as shown in Figure 1. WDFAD-DBR will select node A as a forwarding node, as weighting sum of heights for two hops is greater than any other path. However, node A having a large number of PFNs will suffer from a large amount of receiving and transmitting energy due to the chance of initiating duplicate packets.The causes of duplicate packets has been discussed in Section 3.2. The proposed dolphin-pods routing will give preference to node B for forwarding in order to overcome the above-mentioned problems. When we consider the number of PFNs and number of suppressed nodes, a reasonable amount of receiving energy will be conserved. Moreover, WDFAD-DBR considers the fixed transmission power level for all nodes in the range of a source node, whereas the proposed scheme divides the transmission range into different transmission power levels such that the appropriate transmission energy level is used by the source node to conserve the energy.