# Investigating Master-Slave Architecture for Underwater Wireless Sensor Network
## 3 Problem Statement  
In this research work, we aim to address the problem of high energy consumption of data packet transmission in UWSNs. The two existing protocols i.e., DBR and WDFAD-DBR transmit data packets by broadcasting them across all over the Potential Forwarding Zone (PFZ), and all neighbor nodes receive the transmitted packet. Next, the node with higher priority (smaller holding time) transmits the received packet further while the remaining nodes drop it. In both schemes, there is a wastage of energy in the form of redundant data packet transmission and unnecessary reception of data packets by suppressed nodes. The data packet has a larger size than the other packets (e.g., Neighbor request and Acknowledgment), due to which the nodes consume more energy for transmission.  
WDFAD-DBR is an improved version of DBR and is the basis of our work, therefore, we explain the data packet transmission in this protocol with the help of Figure 1. Node  
\begin{table}
\begin{tabular}{c c c c} \hline
**Protocol Category** & **Protocol** & **Advantages** & **Drawbacks** \\ \hline \multirow{8}{*}{Localization-Free Routing} & DOW-PR [20] & Increase in PDR and & Increase in E2 ED \\  & & Decreased in Energy in & \\  & & energy consumption & \\ \cline{2-4}  & OMR [24] & Higher network & Does not perform well for \\  & & throughput, lower E2 ED, & long-range communication \\  & & energy optimization & because of the fading issue of \\  & & RF waves \\ \cline{2-4}  & QERP [25] & Increase in PDR and & Earlier death of cluster heads \\  & & Decreased in Energy in & because of overloading \\  & & energy consumption and & leading to the creation of \\  & & low packet latency & energy holes \\ \cline{2-4}  & EECOR [26] & Energy efficiency, & Increased delay due to the \\  & & high throughput & communication among \\  & & & various nodes in \\  & & forwarding region \\ \hline \multirow{2}{*}{RRSS [27]} & Energy efficiency & Overloaded nodes because of \\  & & more data in the vector \\ \hline \multirow{2}{*}{UMDR [28]} & Energy optimization, & complications due to the \\  & higher throughput, and & frequent calculations of the \\ \cline{1-1}  & lower E2 ED & next hop and information \\ \cline{1-1}  & & about antenna \\ \hline \end{tabular}
\end{table}
Table 1: \(Cont.\)S is the source node that gathers information about the neighbor nodes by broadcasting the Neighbor request and gets the Acknowledgment packet in response. Next, the S node calculates and assigns the holding time of each node using a fitness function and starts its data packet transmission. As depicted in the figure, node A has a smaller holding time and starts data packet transmission while the other (four) nodes, with higher holding time than A, wait for their turns. Since these suppressed nodes are also in the transmission range of A, they receive the same packet back as node A transmits it. Although these nodes will not become part of further transmission, energy is still wasted due to the reception of packets. All other nodes outside the region of A (suppressed nodes of S) do not receive the data packet from node A and therefore start their transmission resulting in data packet duplication and high energy consumption. For resolving this problem, we propose the ERPMSA-UWSN protocol that mainly focuses on reducing high energy consumption in UWSNs.