## 3 Problem Statement  
The Energy-Scaled and Expanded Vector-Based Forwarding (ESEVBF) protocol [32] expands the holding time of AHH-VBF to suppress duplicate packet generation due to a very small difference between the holding time of the neighbor nodes as compared to the propagation delay. The propagation delay is very high in the harsh underwater environment. Upon generation/reception of a packet from its predecessor, the node forwards the packet to other nodes in its transmission range, which will result in generating a large number of duplicate packets and in more energy consumption if all nodes take part in forwarding. Therefore, it is very challenging to reduce the forwarding nodes to an acceptable level. Till now, all the protocols use the holding time mechanism to suppress duplicate packets. The holding time is calculated in ESEVBF based on: (1) the distance of the PFN from the edge of the transmission range scaled with inverse normalized energy, (2) the distance from the virtual pipeline, and (3) the distance from the sink node of that corresponding node. ESEVBF covers all the factors related to the holding time but it is based only on the first hop. In ESEVBF, the problem may arise due to the presence of void/energy hole found by the PFN of the sender. The proposed scheme will extend the holding time scenario to the second hop. In that case, there will be a higher probability to advance the packet further in the overall distance covered by the two hops from the source node. The proposed system tends to find the more suitable node, which is best with respect to the first hop as well as the second hop. The whole scenario of selecting the forwarder node is depicted in Figure 1. The small red circles represent the source nodes (S and S1), the blue circles represent the Expected First-Hop PFNs and their energies, while the black ones represent the Expected Second Hop PFNs and their energies. Similarly, there are three types of big circles in the figure representing various transmission ranges, i.e., the circles with the solid line boundary represent the transmission ranges of the source nodes, the dashed circles represent the transmission ranges at the first hop, while the dotted ones represent the transmission ranges at the second hop. As depicted in the figure, node S is the source node because it broadcasts a packet and nodes A/B are the receivers of the packet. ESEVBF selects node A for forwarding the received packet, which means that Node A will transmit the packet early in such a way that node B receives it before its own broadcasting. When Node B receives the packet transmitted by A as a duplicate packet, it suppresses both the packets (the original packet received from Source node S as well as the duplicate packet received from node A). The PFN (node C) of node A does not have sufficient energy to continue broadcasting. The proposed system will select node B for forwarding as it has a second hop PFN, which is more favorable with respect to energy and packet advancement. Therefore, the proposed protocol tends to increase the net packet advancement and finds the best favorable routing path with respect to the residual energy. In the second scenario, as shown in the same Figure 1, node S1 has G and F PFNs in its transmission range. When node S1 broadcasts the received/generated packet, nodes F and G receive the packet, and the next forwarder is selected based on the holding time. ESEVBF selects node F as a next forwarder, which introduces the problem of void holes. In contrast, EESEVBF will give preference to node G because there is node H at the second hop, which can further continue the packet transmission process for reducing data loss. The second problem faced in ESEVBF is the hidden terminal problem, as depicted in Figure 2. The source node broadcasts while its PFNs receive the packet. The qualified nodes are prioritized according to the holding time value.