## 2 Related Work
### Communication in Vehicular Networks  
The simplest way to disseminate messages in a VANET is by means of simple broadcast and relay by flooding to entities in range [7]. However, two main problems arise: uncontrollable broadcast storms and non-receiving nodes not located inside the broadcast region. For this, [PERSON] et al., 2020 [2], classified message dissemination approaches as follows:  
1. Dissemination by Intelligent Traffic Lights (ITL). Mobile entities that provoke or detect an emergency create messages communicated to ITLs, and then forward them to other ITLs and vehicles in advance before they reach the emergency zone. Another goal is to provide better routes by adjusting speeds or clearing lanes for emergency vehicles such as ambulances, for example. 2. Dissemination using Internet of Things (IoT). Oriented to the detection and priority flow of emergency vehicles by means of Radio Frequency Identification (RFID) tags and Worldwide Interoperability for Microwave Access (WiMAX) wireless technologies with centralized management for the clearance of lanes and streets. Nevertheless, the proposed solutions are more focused on transportation than on communication issues. 3. Dissemination using Priority Messaging. A broadcast is made before other messages and storms are controlled by an algorithm. Communication is location-sensitive by using the real-time updated location of where incidents happened; despite this, discrimination of messages for storm control generates overheads in message processing in the network. 4. Dissemination using a Clustering Approach. Messages received, either through routing tables or opportunistic receipt, by a member are delivered in a unicast way to heads within groups of neighbor vehicles (clusters) that share a heading and speed at determined times in the environment. Those heads are responsible for broadcasting messages to all vehicles inside clusters. This approach retain a controlled and geographically limited scheme, but flooding still occurs, and it tries to reach every entity currently in the environment. 5. Dissemination using Software-Defined Networks. Central or in-the-cloud entities control data flows by means of on-demand requirement analysis and, in this case, emergency messages are sent dynamically with higher priority among vehicles; however, connectivity with mobility is the main issue, not to mention the fact that data are communicated over previously deployed and dedicated expensive infrastructure or resources. 6. Dissemination using Fog-Based Approaches. Fog computing basically delegates tasks from cloud to edge devices that will allow the dissemination of messages dynamically. Figure 1: VANET general architecture and communication kinds. These approaches nonetheless inherit the issues and requirements related to resources deployment as those seen under Software-Defined Networking (SDNs). * Dissemination using 5G Technology. These approaches use the benefits given by 5G technology over mobile devices, such as connectivity and a broader bandwidth. Some drawbacks are that the operation is offered by third-party carriers, and the relatively new and expensive cellular technology requires time to be deployed to rural zones or zones through which highways are routed. The classification of approaches for message dissemination provided by [2] does not match or exceed the performance of other feasible approaches, while the means of data transport are also classified as mechanisms. Other works include the following studies, including a proposed classification for message dissemination approaches in vehicular networks. In [19], the authors propose a synchronous system for clustered vehicles traveling in the same direction for highway scenarios with only a V2V scheme. Their objective is to deliver the warning messages with higher priority, given that these kind of messages are time-sensitive.