# A Roadside and Cloud-Based Vehicular Communications Framework for the Provision of C-ITS Services
## 1 Introduction  
C-ITS infrastructure is being deployed throughout the world with the main goals of improving travel experience, ensuring traffic safety and efficiency, and reducing environmental damage. For instance, the C-Roads initiative in Europe [1], the Connected Vehicle Pilot Deployment Program in North America [2], and the National Intelligent Connected Vehicle (Shanghai) Pilot Zone in China [3], among others, are recent examples of such endeavors. Wireless vehicular communications, also known as Vehicular-to-Everything (V2X) communications, are essential to these types of infrastructures, facilitating the exchange of information among road users, such as vehicles and pedestrians, and between them and the roadside infrastructure. The most popular contender access technologies for V2 Xcommunications include European Telecommunications Standards Institute (ETSI) ITS-G5 based on Institute of Electrical and Electronics Engineers (IEEE) 802.11p and 3 rd Generation Partnership Project (3 GPP) Cellular-V2X (C-V2X), which includes both 5G Uu (cellular, long range) and PC5 (device-to-device, short range) interfaces. On the roadside infrastructure, Roadside Units (RSUs) equipped with V2X communications can also improve the perception of the overall traffic system by employing multiple sensors, such as traffic radars and cameras. These RSUs can be placed at strategic high points and critical safety locations, such as intersections and lane merges, to provide an essential view of the road state. The sensor data collected by the RSUs are processed and then disseminated to neighboring vehicles and to the road operator. This information is specially important given the nature of wireless communications, since range issues and obstacles (buildings, vehicles themselves, etc.) can negatively affect the Packet delivery Ratio (PDR), thus reducing vehicles' awareness of each other's presence on the road. The C-ITS management platforms are the primary instrument for road operators to track all traffic information and events that take place on the roads under their supervision. Roads populated with V2X communication-enabled RSUs can inform the C-ITS platform of the position and dynamics of connected vehicles, as well as events reported by these, either automatically if the vehicle is autonomous, or manually reported through a Human-Machine Interface (HMI). Conversely, the road manager can disseminate specific warnings generated in the C-ITS platform to the areas with coverage provided by the RSUs. These warnings include accidents, roadworks, traffic jams, and other incidents. The road manager must be able to effectively handle, analyze, and extract valuable information from the vast amounts of data exchanged in vehicular networks [4]. To achieve this, the efficiency of the protocols used to distribute and collect messages in vehicular environments is critical to the design of an architecture that supports and provides C-ITS services. Developed in the context of the STEROID--Verification and Validation of Advanced Driver-Assistance Systems (ADAS) Components for Intelligent Vehicles of the Future--research project [5] and the pan-European C-Roads initiative [1], we here present the design and implementation of a roadside and cloud architecture for the provision of C-ITS services in infrastructure-based V2X networks managed by a motorway operator (A-to-Be, the R&D company of Brisa group; [[https://www.brisa.pt/en/about-us/companies/a-to-be/](https://www.brisa.pt/en/about-us/companies/a-to-be/)]([https://www.brisa.pt/en/about-us/companies/a-to-be/](https://www.brisa.pt/en/about-us/companies/a-to-be/)), accessed on 25 February 2023) and a telecommunications research institute (Instituto de Telecomunicacoes; [[https://www.it.pt/](https://www.it.pt/)]([https://www.it.pt/](https://www.it.pt/)), accessed on 25 February 2023) in Portugal. The rest of the paper is organized as follows. Section 2 provides a description of the related work in the area.