## 3 Proposed System Model
### DAWPC-MAC Model Overview
The RTS and CTS are transmitted using the maximum power level \(P_{\text{max}}\), while the data packets are sent using the minimum necessary power to effectively reach the destination. In an underwater wireless sensor network (UWSN), the nodes are spatially distributed in a 3D environment, where their positions are represented by three coordinates: \(x\), \(y\), and \(z\), corresponding to the locations of the nodes along the X, Y, and Z axes, respectively. Communication range is an important aspect of the network performance and prevents from preparing communication models like signal strength, energy consumption, and communication efficiency between two nodes. This range is measured as the distance between the nodes. In form, the Euclidean distance formula in 3D space is used to derive straight line distance between 2 points according to their spatial coordinates. The formula is expressed [41] as in Equation (6):  
\[D=\sqrt{(x_{2}-x_{1})^{2}+(y_{2}-y_{1})^{2}+(z_{2}-z_{1})^{2}}. \tag{6}\]where \((x_{1},y_{1},z_{1})\) and \((x_{2},y_{2},z_{2})\) are the coordinates of the two nodes in 3D space. Euclidean distance calculates the distance between two nodes by taking the square root of the sum of the squared differences between each node's respective coordinates. We then define this distance to quantify how far apart those two nodes are in the shortest line, known to be fundamental in the approach to the signal propagation as well as the interaction dynamics of a communication network. The Signal-to-Noise Ratio (SNR) plays a crucial role in communication systems as it evaluates the signal's quality in comparison to background noise. SNR is determined by dividing the signal power by the noise power.Mathematically, this is expressed as in Equation (7):  
\[\text{SIR}_{\text{threshold}}=\frac{P_{\text{required}}\times P_{r}}{P_{o} \times G}=\frac{\text{Signal Power}}{\text{Noise or Interference Power}} \tag{7}\]  
Here, \"Signal Power\" is the power or amplitude of the transmitted signal whereas Noise Power is the power of the interfering signals or background noise that disrupt the signal in Equation (8). \[T_{timeout}=T_{WS}+T_{wait}. \tag{8}\]  
The wake-up signal power \(P_{\text{WS}}\) is dynamically adjusted based on the communication conditions, which can be either initial low power, increased power for extended coverage, or sleep mode. The wake-up signal duration \(T_{\text{WS}}\) and the waiting time for a response \(T_{\text{wait}}\) are defined. The timer is reset each time the power state changes, ensuring that a fresh waiting period is started whenever the wake-up signal power is adjusted. The timer ends if no response is received within the timeout period. If a response is received during this time, communication continues; otherwise, the receiver transitions to sleep mode, and the power \(P_{\text{WS}}\) is reduced to zero to optimize energy consumption. Each time the power state is adjusted, the timer is restarted, and communication continues as long as a response is received within the allocated time. Critical data packets \(D_{crit}\) (e.g., emergency data, object-tracking information) are prioritized over routine data (e.g., environmental monitoring) based on urgency and network conditions.