The following is a brief introduction to the topic:
C-ITS allows vehicles to communicate with each other. Its development focuses on improving safety, comfort, traffic, and energy efficiency. Its main communication strategy is vehicle-to-everything (V2X), in which data sharing is performed through vehicle-to-vehicle communication (V2V) and vehicle-to-infrastructure communication (V2I). In a CITS environment, cooperative-awareness messages (CAMs). 1 The decentralized environmental notifications (DENMs), on the other hand, provide real-time data about individual vehicles. 2  provide information about events that could have an impact on traffic or road safety (e.g., roadworks, accidents, vehicle failures, etc.), allowing proactive incident prevention. Despite the novelty of the concept, it is still not possible to fully record and analyze the impact that C-ITS services have on road networks. 3 Due to the C-ITS’s cooperative nature, its participants share a large amount of data. These data can reveal valuable information about the performance of the C-ITS system. Road and telecommunications operators, as well as the end users, could detect critical information, such as system failures or anomalies. These units are installed along the roadside and provide access to the V2I infrastructure for vehicles. These units are essential and most useful when there is a low density of C-ITS-equipped vehicles 4 ]. RSUs also provide services to vehicles that are implemented in the infrastructure. RSUs provide services that are implemented on the infrastructure. 5 ]:
- Traffic light maneuver is a service that administers the generation and transmission of Signal Phase and Timing Messages. Its goal is to control access by vehicles to intersections and conflict areas. It provides safety information for cars at a meeting, including the current status of the traffic signal and its future status.
- Road and lane Topology (RLT) is a service that manages the transmission and reception of Map Extended Messages. A MAPEM message contains a digital topology map of a particular area. This topology defines lanes, crossings, conflict zones, and allowed maneuvers.
- Infrastructure to Vehicle Information (IVI) provides information on road signs, such as road warnings or contextual speed limits.
In low-density scenarios, an RSU failure can lead to a loss of infrastructure services (or partial coverage) in an area that is supposed to be covered. It may also result in a degradation of C-ITS as a whole. In order to ensure the proper functioning of the C-ITS system, RSUs need to be monitored and their failures identified and reported immediately. This study has a specific objective: to detect transmission failures in an RSU. The end user (vehicles) will be responsible for detecting the failure and informing road operators.
- New method to detect RSU failures in vehicles.
- Evaluation of the method using a real dataset generated by CAMs in a CITS naturalistic driving environment in three countries: France, Germany, and Italy.
- Proposal of a C-ITS message that will be used to alert users to detected problems.
This paper is organized as follows: Section 2 The C-ITS is briefly introduced to help understand the role played by the communication stack over the CITS. Section 3 Presents our solution as well as the mechanisms that we use to detect RSU failures. Section 4 This section describes the message that must be sent by a vehicle to inform it of the RSU’s status. Section 5 presents the conclusions and future works.
State of the art
This section discusses various aspects of our work, including the C-ITS system, which we analyzed for this paper, the anomaly detection using relevant data sets, and the clustering algorithm used to classify the datasets.
2.1. C-ITS Systems
In Europe, C-ITS is based on a communication stack that ETSI has defined. The Facilities layer was designed to interface efficiently with the Application layer (closer to the driver and vehicle sensors) over the Network layer. This layer provides a variety of messages to address a range of use cases, including traffic light control, road works warnings, and traffic jam detection. We have focused our study on one specific message type: the CAM. The goal of CAMs is to create a cooperative consciousness among vehicles. Its use is to give dynamic information about the car, such as its location, speed, direction, etc. A CAM is an intermittent message sent between 1 Hz and 10 Hz, depending on the vehicle’s speed. It can be sent via V2V or I2I communications. Figure 1. Each car must have a pseudonym certification. The vehicle’s messages could be forwarded to distant vehicles using multi-hop forwarding.