## 3 Network Architecture  
The network architecture of the ESEVBF protocol is composed of anchored nodes, relay nodes, and sink nodes, as depicted in Figure 1. The terminus nodes/sink nodes are centralized stations consisting of acoustic and radio modems. They communicate with each other and with the external network through the radio links. Sink nodes are fixed at the water surface. The data received by any sink node is considered to be a successful delivery to its destination. On the other hand, relay nodes are movable with the water current, while anchored nodes are fixed at the bottom. The sensor nodes communicate with each other through an acoustic link. The speed of the acoustic signal (1500 m/s) is much smaller than that of the electromagnetic signal (\(3.8\times 10^{8}\) m/s). Environmental monitoring and underwater tectonic plates monitoring are the typical applications of the network. _Timer Value Calculation Based on the Packet Advancement from the Source Node to the Second-Hop Potential Forwarding Node and on the Energy Tax Value in the Forwarding Region_  
The proposed protocol distinguishes between five distinct kinds of packets, which are Neighbor Request, Acknowledgment, Container, Announcement, and Data Packet. The sensor nodes are set up in the various locations. When the packet is ready to be forwarded, the timer mechanism is used to choose the next forwarder. The packet is transmitted by the source node to all of the potential forwarding nodes (PFNs), which then receive it. In the event that the PFN does not change its position at any point in the locality, then in the case of real life in the simulation, a single node will be chosen every time the source broadcasts the packet. Because of the repeated selection, the currently chosen node will enter a dead state after a certain amount of time has passed. Therefore, the sensor nodes move around and their positions change in a random pattern. These nodes are qualified to act as forwarding nodes if the current source node is shallower, and if the distance between them is closer together than the transmission distance. The Neighbor Request Packet is broadcast by the source node in order to locate the forwarding nodes that it needs. The Neighbor Request Packet has the format \(N_{req}(id,d,Type_{packet})\), where it is an unchanging integer number that is specific to the sensors nodes, d is a field that was initially assigned to each node during the initialization phase, which stores information regarding the depth, while \(Type_{packet}\) is a number in binary format that is used to distinguish each of the packets. As soon as a Neighbor Request Packet is received, the neighbor sends a Neighbor Acknowledgment Packet in response. In the configuration of an \(Ack_{packet}(id,d,residual_{energy},Type_{packet})\), id is a unique number that is given to each node, d is the data packet type, and \(residual_{energy}\) is residual energy or energy status and \(Type_{packet}\) denotes the packet type, i.e., in the current case, it will denote an Acknowledgement Packet. At the first hop, the PFNs of the source node communicate with one another using packets through Container Packets, also known as CPs, to exchange their priorities. Whenever a data packet is delivered to a neighbor node from the source node, the neighbor node immediately calculates its own timer value, in addition to determining the bare minimum required timer for the second hop. The structure of a Container Packet can be described as \(Can(id,\mathit{Timer}_{Hopf},\mathit{Timer}_{Hopf2},Type_{packet})\), where  
Figure 1: Network Architecture of the proposed work. id is the unique number of the sending node, \(\mathit{Timer}_{Hopf1}\), is the timer value at first hop, and \(\mathit{Timer}_{Hopf2}\) is the timer value at the second hop (the minimum timer value among the second-hop forwarder of the applicant adding \(\mathit{Timer}_{Hopf1}\) and \(\mathit{Type}_{packet}\) represents the packet type, i.e., in this case, the container packet.