## 3 Proposed Model and its Phases
### Network Transmission Phase (NTP)  
In the network transmission phase (NTP), the TDMA schedule is created with cluster formation. Since the main objective here is to reduce the drain of node energy to prolong the transmission time of the network, we introduce a different mechanism by using threshold values in our algorithm to minimize energy dissipation when no or minor change is observed in the physical system. The proposed NTP process is shown in Figure 8.  
In this paper, we consider two types of sensors available on the wireless nodes for collecting two types of data from the environment, temperature \(T_{mp}\) and humidity \(H_{mdy}\), which are distinguished by MAC addresses. The selection of a sensor for a node depends upon a boolean value \(RND\) in each round. If \(RND=1\) then \(T_{mp}\) will sense and broadcast updated value, if required, and if \(RND=0\) then \(H_{mdy}\) will broadcast updated sensed value, if required, to their respective cluster heads. After forming clusters, each CH will broadcast parameters controlled by the BS in each round. In our proposed model, we use two types of threshold values adjusted by the BS in the NTP. The hard threshold represents the maximum (\(T_{max}\), \(H_{max}\)) and the minimum (\(T_{min}\), \(H_{min}\)) acceptable values of the network. The soft threshold represents small interval values (\(T_{soft}\), \(H_{soft}\)) to prevent a node from communicating when minor or no change occurs. Furthermore, in our proposed model, when the system is stable, no transmission may be observed due to predefined threshold conditions. However, this may lead to an undesirable scenario when an alive node is considered a dead node [21]. To overcome this challenge, we introduce a counter (C) that is updated when a node performs no transmission for a fixed  
Figure 8: Flow control of the proposed network transmission phase. number of epochs. Afterward, the node will transmit its sense, and probably unchanged value, of the selected sensor to keep it alive for the WSN. The node resets the counter after each transmission. If \(T_{old}\) and \(H_{old}\) are last transmitted values, \(T_{new}\) and \(H_{new}\) are sensed values in the current epoch, then the transmitting conditions for each sensor are shown in Figure 8. We define three possible conditions when a non-cluster head node will transmit updated information of the selected sensor to its CHs. These conditions are:  
1. The hard threshold scenario when new sensed values of \(T_{new}\) or \(P_{new}\) are greater than the maximum accepting values (\(T_{max}\), \(H_{max}\)) or lesser than the minimum accepting values (\(T_{min}\), \(H_{min}\)). 2. The soft threshold scenario when the difference in previously transmitted values (\(T_{old}\) and \(H_{old}\)) and new sensed values (\(T_{new}\) or \(P_{new}\)) is unexpectedly larger or smaller than the expected change (\(T_{soft}\), \(H_{soft}\)). 3. The stable network scenario when the network is stable, and the node is not transmitting its values (\(T_{new}\) or \(P_{new}\)) since the last four consecutive numbers of rounds. In the network's initialization phase, the previously transmitted values of all nodes will be set as \(T_{old}=0\) and \(H_{old}=0\). The selected cluster heads will receive the values of hard threshold and soft threshold from the BS at CHSP and broadcast them to non-cluster heads during MAP. In the first round, all nodes will initialize their values of one of the sensors, temperature or humidity, depending upon their self-generated \(RND\) value which is either 1 for the temperature sensor or 0 for the humidity sensor. Later on, the other sensor will be initialized at its turn. The BS can change the threshold values after receiving a signal frame based on the predefined routines or using software-defined network (SDN) techniques [43]. After a few rounds, the network stability increases, which further reduces the inter-cluster communication resulting in a prolonged network lifetime. Cluster heads aggregate the collected data from member nodes.