# Automated Evaluation of C-ITS Message Content for Enhanced Compliance and Reliability
## 2 Materials and Methods
### Description of Testing Tools
#### 2.2.2 C-TTS SIM  
C-ITS SIM is a specialized tool developed for testing third-party C-ITS units and their practical implementation in C-ITSs. It ensures interoperability and validation by supporting various functionalities, including the broadcasting and reception of CAMs and DENMs, which are crucial for this article.  
The tool consists of specific software connected to two On-Board Units (OBUs). This dual-OBU setup is essential for accurate verification of message transmission and reception:  
Figure 4: Map visualization example showing the speed represented by different colors and the type of message or its source (e.g., CAM messages) using various pictograms. The color gradient indicates speed levels, while specific icons highlight the message type or origin.  
* Broadcasting Verification: One OBU transmits the messages while the second OBU receives and verifies them. This setup allows for accurate identification of any issues with message transmission, confirming whether the problem lies with the third-party unit or not.
* Reception Verification: For reception tests, the dual-OBU setup enables double-checking to ensure that any issues with receiving messages are not due to the C-ITS SIM itself. The software allows users to configure expected parameter values for messages and verifies if these parameters are met. An example of receiving messages is shown in Figure 5, which displays the basic interface. On the left side, you can see all the captured C-ITS messages, including those transmitted by the C-ITS SIM. In the center, there is a regularly updated map displaying C-ITS messages according to their geographical location. On the right side, there is a list of OBUs connected to the software, along with the option to connect additional devices.  
The tool is designed to handle CAMs and DENMs, among others, but for the purposes of this article, its focus is on how well these messages are transmitted and received. The approach differs from Karlos, as C-ITS SIM involves configuring the desired message parameters in the software and then verifying whether the captured messages meet these parameters. The configuration of these parameters is illustrated in Figure 6.  
Users can configure the tool to include specific parameters for CAMs and DENMs. This feature enables targeted testing by allowing users to select which parameters to analyze, such as verifying speed values or other critical data.  
The tool automatically logs communication during tests, storing data in PCAP format for easy analysis. It allows users to review and replay test scenarios, providing valuable insights into the performance and accuracy of the C-ITS units.  
C-ITS SIM is versatile and can be used for both lab-based and field testing. It has been employed in various testing environments to refine its functionality and address real-world challenges. The tool is designed to be adaptable to new standards and evolving testing needs. It has also been successfully utilized in both national and international testing as part of the C-ROADS project mentioned earlier. Further details about this software, including its additional features, can be found in the article [26].  
Figure 5: Summary for CAMs in C-ITS SIM, showing a list of received messages on the left side. The map displays the location of C-ITS messages, while additional settings are available on the right side.