## 3 Proposed Techniques
### Initial Phase
#### 3.1.2 Independent Nodes (INs)
During

Figure 3: The announcement messages in the static approach: (a) the Normal member node (N)’s message; (b) the Cluster Head (CH)’s/ Independent Node (IN)’S messages. Figure 2: The general topology of a WSN using the proposed approach. the round period, other broadcasting messages are used in order to update the RTs. The updated messages of Ns usually include their IDs, cluster IDs, and residual energy (Figure 5a) and the updated messages of the CHs and INs contain their IDs, level numbers, and residual energy (Figure 5b). ### Tables Preparation Phase

As it results from the previous phase, all the network nodes are able to generate their RTs. In both approaches, the N, which is located on the second level in each cluster, creates its RT. It usually uses the announcement messages, which are received from the Ns in the first level. Afterward, it transmits a JOIN-REQ to the source of the message. Subsequently, the N that receives the request checks the availability in its TDMA scheme. If there is an empty slot, it allocates for the requester. Then, it transmits its response to it. Thus, the Ns that send approvals to the requests can be added to the RTs. The CHs and INs, which are located on the second and upper levels, generate their RTs based on the announcement messages that have been transmitted from lower levels. Accordingly, all messages, which are received from the same and upper levels, will be neglected. Thus, the CHs and INs transmit the JOIN-REQ messages to each other and they wait for the approval to enable them to create their RTs. Figure 6 shows the TDMA schedules for the different types of the network's nodes during one round. Obviously, the TDMA schedule of the N is only dedicated for its neighboring nodes at the same cluster, whereas the TDMA schedule of the CH has been divided into two sections: the first part is allocated to its member nodes and the second part is allocated to other neighboring CHs and INs. Finally, the slots of the TDMA schedule of the IN are only assigned to the neighboring CHs and INs. Figure 4: The announcement messages in the dynamic approach: (**a**) the N’s message; (**b**) the CH’s/IN’S message. Figure 5: The updated messages in the dynamic approach: (**a**) the N’s message; (**b**) the CH’s/IN’S message. ### Routing Phase

After completing the previous three phases, the network becomes ready to route the sensed data. Each technique uses a particular approach for routing the network data, as is described in the next paragraphs. #### 3.4.1 Static Multi-Hop Routing Technique (SMR)

This section provides a static technique for transferring the data along the network levels toward the BS. As its name implies, this technique selects static routes from the network nodes to the BS at the beginning of each round and continues using it until the round is finished. By doing so, the proposed technique assumes that the data transmissions are divided into two groups: the intra-cluster routing and inter-clusters routing. Below, the two groups are debated in detail. Eventually, the node's energy recedes based on the transmission distance, which is calculated by Equation (2). * Intra-cluster Routing

As mentioned above, all the network clusters are split into two levels around the CHs, where the length of each one is \(d_{o}/2\). Each N computes its distance to the CH (\(N_{D\text{-}CH}\)) to determine its level. The Ns of the first level send their collected data to the CH directly. On the other hand, the Ns of the second level use their RTs to select their routes. Here, the minimum distance value in the RT will be selected, which may be the distance value to the CH or to another neighboring node in the first level. The details of the intra-cluster routing process are giving by the pseudo-code in Algorithm 2.