# An Improved Weighted and Location-Based Clustering Scheme for Flying Ad Hoc Networks
## 3 Preliminaries
### System Model  
The hierarchical system architecture is depicted in Figure 1. In the ground level, GCSs are deployed. We assume that the GCS has knowledge of the topology of FANETs [28]. The GCS formulates clusters and maintains the backbone routing table for communicating with CHs. GCS broadcasts central control commands to all UAVs through CHs.  
The aerial level is dominated by UAVs. In the system, it is assumed that all the UAVs are equipped with location-aware components and wireless communication interfaces. Specifically, UAVs are embedded with inertial measurement units (IMUs) and GPS chipsets for measuring velocity and location information and have the capability of routing. The UAVs are then clustered according to the proposed clustering scheme. Each cluster is composed of a CH and CMs. The CHs are responsible for inter- and intra-cluster communications, cluster management, and communications with GCSs. The CH maintains its cluster by updating the list of CMs, according to the HELLO message received from the CMs. The CMs perform missions under the command control of CHs. Furthermore, the CHs are adaptively updated, and the CMs are candidates for CH selection.  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**Proposals** & **Method** & **Clustering Overhead** & **Location Awareness** & **Stability** & **Mobility** & **Energy Efficiency** & **PDR** & **CH Chan-** & **Communicate-** \\ \hline LEACH-C [8] & Centralized & High & ✓ & ✓ & ✓ & \(\times\) & \(\times\) & ✓ & \(\times\) \\ HEED [9] & Distributed & High & \(\times\) & ✓ & \(\times\) & ✓ & ✓ & \(\times\) & \(\times\) \\ SDN-MQIT [10] & Distributed & Low & \(\times\) & ✓ & \(\times\) & \(\times\) & ✓ & \(\times\) & ✓ \\ CBLADSR [22] & Distributed & High & ✓ & \(\times\) & ✓ & ✓ & ✓ & \(\times\) & \(\times\) \\ WSCA [21] & Centralized & Low & ✓ & ✓ & ✓ & ✓ & ✓ & ✓ & \(\times\) \\ EALC [13] & Hybrid & Low & \(\times\) & \(\times\) & ✓ & ✓ & \(\times\) & ✓ \\ MPCA [14] & Dynamic & High & ✓ & ✓ & ✓ & \(\times\) & ✓ & \(\times\) \\ ACO [23] & Hybrid & Moderate & \(\times\) & ✓ & ✓ & \(\times\) & ✓ & ✓ & \(\times\) \\ GWO [24] & Hybrid & High & \(\times\) & \(\times\) & ✓ & \(\times\) & ✓ & \(\times\) & \(\times\) \\ IWLC & Centralized & Low & ✓ & ✓ & ✓ & ✓ & ✓ & ✓ & \(\times\) \\ \hline \hline \end{tabular}
\end{table}
Table 1: IWLC performance positioning with other clustering schemes in FANETs.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Notation** & **Meaning** & **Notation** & **Meaning** \\ \hline \(I\) & UAV ID & \(E_{T}\) & Total energy consumption \\ \(B_{1}\) & Intra-communication bandwidth & \(E_{f}\) & Flying energy consumption \\ \(B_{2}\) & Inter-cluster communication bandwidth & \(E_{Tx}\) & Transmitting energy consumption \\ \(N\) & Number of UAVs & \(E_{Rx}\) & Receiving energy consumption \\ \(K\) & Number of clusters & \(E_{i}\) & Remaining energy ratio of node \(i\) \\ \(S\) & Set of UAV nodes & \(q_{i}\) & Set of neighbor nodes of node \(i\) \\ \(k^{*}\) & Optimal number of clusters & \(Nd_{i}\) & Node degree of node \(i\) \\ \(CH\) & Cluster Head & \(N_{i}\) & The adaptive node degree of node \(i\) \\ \(CM\) & Cluster Member & \(M_{i}\) & Relative mobility of node \(i\) \\ \(R\) & The maximum transmission range of UAVs & \(D_{i}\) & Average distance of node \(i\) and neighbors \\ \(C\) & Set of clustering centers & \(v_{i}\) & Speed of node \(i\) \\ \(CL\) & Set of clusters & \(d_{ij}\) & Distance between node \(i\) and \(j\) \\ \(W_{i}\) & Weighted summation-based value of node \(i\) & \(GCS\) & Ground control station \\ \(E_{0}\) & Initial energy & \(PDR\) & Packet delivery ratio \\ \hline \hline \end{tabular}
\end{table}
Table 2: Notations in this paper.