# Design of Edge-IoMT Network Architecture with Weight-Based Scheduling
## 2 Related Works
### Priority-Based Clustering Scheme
#### 3.3.1 Phase 1: Clustering and Inter-CH Selection  
For establishing a cluster-based network topology, each member scans how many neighboring devices can join the cluster by broadcasting, and then estimates the distances of the nearby devices with the RSSI value obtained during the handshake process. When a  
Figure 4: A scenario of patients with different physical signals of priority weights.  
Figure 3: Structure of compression with wavelet transform.  
member (say node \(i\)) broadcasts its priority information (i.e., levels 1-3) to other neighboring devices, the countdown timer, \(WT_{i}\), is triggered. When the device receives a message from a neighboring node and the timer expires, then it sends an address information to other nodes to indicate that it has become a CH, and the adjacent nodes join the cluster at \(WT_{i}=0\).  
Similarly, the adjacent CHs can follow the above procedures to perform the inter-CH selection. Accordingly, based on the neighboring network density and patient's priority information, we may set the initial random waiting timer from the distribution \(\beta\cdot WT_{i}^{(0)}+\alpha\)[42]. The algorithm mentioned above is based on the countdown timer and describes the parameters by priority and RSSI. \(\alpha\) is the priority of each member, and we have three levels in this system. For instance, for level 1 (highest level) \(\alpha=0\) and level 3 (lowest level) \(\alpha=2\). There is a situation in which multiple patients of the same priority may be in the same ward, so the RSSI value of the device and the relay, \(\beta\), is a critical parameter of the formula that the one closer to the relay will count down faster. Therefore, according to the different priority levels, higher priority devices will receive a shorter waiting time, which means it is more likely to be the head, because some patients with higher priority are high-risk people that require frequent and real-time monitoring. The conceptual communication architecture after clustering and inter-CH selection are shown in Figure 5 (left).  
Without loss of generality, Figure 5 (right) shows four zones with different priority levels for characterizing the topological behavior of the proposed system. The upper right and lower left zones are general wards, where the people in these areas are with priority levels 2 or 3; the people in the upper left zone are all with priority level 3; the lower right zone is the most urgent area, where the people in this area are with priority levels 1 or 2. Moreover, a CH with a different color represents a different priority level. Denote the stars, triangles, and squares as the CHs with priority levels of Level-1, Level-2, and Level-3, respectively, for transmitting the sensing data. The green dots are fixed relays located in each zone, and the cyan-blue dot in the middle is the base station. Figure 6 illustrates the flow diagram of clustering procedures.  
Figure 5: Network clustering and inter-CH selection (**left**); a typical run of network topology (**right**), where a solid line and a dotted line represent the information directions from an inter-CH to a relay node and a CH to an inter-CH, respectively.