## 3 Network Overview  
In our work, each section (i.e., cluster) of the road is broken down into K sections. The RSU manages the nodes and communication in a cluster for each segment. Each node is equipped with one IEEE 802.11b-based transceiver. The spectrum is divided into channels that do not overlap (16 channels per RSU separated by 5 MHZ), with transmission and power mask restrictions comparable to the ISM band.  
Each vehicle has radio communication equipment, and the RSU that operates as a relay point for other nodes. Moving vehicles are connected using statically deployed access points or base stations (RSUs). Connecting vehicles to RSUs enables more precise and efficient traffic control, thereby significantly lowering traffic congestion, accidents, and pollution. Vehicles have onboard sensors. A GPS receiver, speedometer, accelerometer, and digital map are among the sensors that help a vehicle gather road data. The road condition is sensed by each node in the cluster and reported to the RSU. In order to protect the lives of drivers on the road, the RSU transmits emergency safety alerts to all vehicles after collecting and evaluating road data. Each vehicle is assumed to be inside the range of the \(i^{th}\) RSU if and only if the following condition is met:  
\[S_{j}^{i}\geq\delta \tag{1}\]  
where \(S_{j}^{i}\) is the signal power received at the \(i^{th}\) RSU from the \(j^{th}\) node, and \(\delta\) is the threshold for signal power. Signal power is computed as described in [21]. A large number of RSUs are distributed over the street. The RSU is responsible for the management of all vehicles registered in its segment. Each vehicle is managed with exactly one RSU. Each node has a unique ID, which can be the MAC address of the node. We secure the safety messages transmitted between network nodes by encrypting them with symmetric key cryptography. The node has private and public cryptographic keys, a certificate issued by the RSU. The \(j^{th}\) node selects the \(i^{th}\) RSU for coordination that has the strongest signal as follows:  
\[R_{j}^{i}=S_{j}^{i} \tag{2}\]where \(R\) is the set of RSUs in the street. The \(i^{th}\) RSU (cluster head) maintains a list of its nodes \(L_{i}\). \(L_{i}\) is broadcast to all cluster members.  
Vehicles in our work move at random and vary their speed at will. At each road intersection, vehicles choose a way at random. When a vehicle selects a direction at an intersection, it proceeds straight until it reaches the next intersection where it can change direction. Figure 1. illustrates the architecture of VANET.  
Definition 1: VANET can be represented as a network graph \(G_{1}=(V_{1},E_{1})\), where \(V_{1}=(v_{1},v_{2},\ldots,v_{n})\) and is a collection of \(n\) nodes, comprising vehicles and RSUs, and \(E_{1}=\{(i,j):i,j\in V_{1}\}\) and is the set of links.  
Definition 2: In our model, the graph \(G\) is utilized to represent the city's roads. \(G_{2}=(V_{2},\ E_{2})\) and is a graph made up of edge set \(E_{2}\) and vertex set \(V_{2}\). The road over intersections \(v_{i}\) and \(v_{j}\) is represented by the edge \(e_{i,j}\). The driver can drive directly from intersection \(v_{i}\) to intersection \(v_{j}\). We call \(e_{i,j}\) a link, and a road is the undirected path that connects vertex \(v_{i}\) with vertex \(v_{j}\).