## 5 BN-MAC Protocol Design
### Selection of the BN  
The BN is selected periodically based on the BN volunteer selection process (BNVSP), which is similar to the process used in [38]. The BNVSP chooses the BN based on the available energy and memory allocation resources. No one node is compelled to declare itself as a BN based on a probability-based calculation. Each sensor node possesses a different energy level in the region after monitoring the event at any given time. The node energy level involves several factors, such as the sleep/wake-up schedule, amount of data received, and amount of data transmitted. The sensor nodes are actively involved in monitoring the events and forwarding the data of the targeted events to the BN. This situation leads to the death of the BN before the other nodes that are not actively involved. Thus, the BN faces a shortage of energy. To overcome this problem, the proposed BNVSP helps to determine the energy level of each node to select a BN based on the maximum residual energy of the sensor node in each region. Each sensor node announces its residual energy after completing the event monitoring process. This maximum residual energy amount determines whether the node should be considered a BN candidate or not but depends on the residual energy of the sensor node and the distance from the node to the base station. The BN is selected based on the energy level using the BNVSP and level of energy information (LEI) algorithm, as shown in Table 1. The LEI function is used to determine the level of energy for  
Figure 11: Throughput under heavy traffic using a low duty cycle. each node, and the BNVSP is used to select the BN. We categorize the energy of sensors into six levels is given in Table 1. Algorithm 1 determines energy level for each sensor node. When the energy level of the BN that is already working decreases, the responsibility is shifted from one BN to another BN using the election flag bit (EFB), a signal alert sent by BN in the network for the election of new BN when decreasing its energy level. The EFB specifies the process of the immediate BN election. The proactive method is used to select the next BN to reduce the overhead associated with this process. The base station broadcasts a short preamble message to each WSN node. Each node calculates its distance from the base station based on the signal strength. The node that \begin{table}
\begin{tabular}{c c} \hline
**Level of Energy** & **Voltage Level of Sensors** \\ \hline Very High & 3.3 to 3.7 V \\ High & 3.0 to 3.3 V \\ High Moderate & 2.7 to 3.0 V \\ Moderate & 2.4 to 2.7 V \\ Low & 2.1 to 2.4 V \\ Lowest & \textless{}2.0 V \\ \hline \end{tabular}
\end{table} 
Table 1: Showing distribution of energy level of sensor node. receives a short preamble becomes a candidate for the BN. Other factors are also considered when selecting the final BN, including the energy of the BN consumed during the contention time for election (comparison time of the energy level), the energy consumption of the sensor node in each state, and the time spent in each state and the transmitted data at each step. All candidate BNs check their radio range and residual energy. The radio range is selected by the short preamble sent by the base station, and the residual energy is selected using the BNVSP, as shown in Table 1. The residual energy level for choosing the BNs is determined as follows:  
\[LEI=\sum_{k=1}^{3}E_{k}\,\pi_{k} \tag{5}\]  
where \(E_{k}\) is the energy consumed by each sensor node in each state and \(\pi_{k}\) is the time spent in each state. Thus, 1 is \"radio on\" for receiving traffic, 2 is \"radio off\", and 3 is transmitting the data packets. Let us determine the residual energy level of each sensor node.