# Simulation-Based Evaluation of V2X System with Variable Computational Infrastructure
## 3 Materials and Methods
### Description of the Simulation Environment and Experimental Scenarios
Each scenario employs two RSU placement schemes:  
Scheme 1: RSUs are placed as densely as possible, with a data collection and transmission device at each road section or block. Data transmission to the higher level is carried out independently by each RSU over a dedicated communication channel (possibly fiber optic). The coverage areas of different RSUs may overlap. OBUs can sequentially query the least loaded RSU within their coverage area for data exchange. The main drawback of this arrangement is the high cost of network organization and its \"noise\" due to numerous cross-requests. Scheme 2: RSUs are sparsely placed on the map, with the sole condition that the entire map is covered by RSU coverage areas. For centralized interaction with the EC, roadside units are grouped into clusters with a shared cache. A primary element is selected within each cluster to interact with the EC. While significantly reducing system management costs, this scheme may increase data loss within the system and potentially lead to complete system blockage. The fundamental principles underpinning the operation of Scheme 2 can be formulated as follows:  
1. The interaction model includes only four system elements: OBU, RSU, EC, and CLOUD. 2. As previously mentioned, using mRSUs significantly improves system efficiency. Mobile RSU movement routes are chosen according to designated public transport routes. mRSUs move on a schedule, enabling prediction of their location and anticipated appearance at specific points. The main disadvantage of this scheme is the presence of idle mobile RSUs that are not involved in system operation during periods of low network load. However, this is expected to be mitigated by high traffic flow or long mRSU travel routes. Within this model, all mRSUs are assumed to be en route according to the schedule. 3. This scenario proposes a new mRSU management scheme where each system element is responsible for serving a specific map area. Alternatively, it can be stationed in a depot until notified of increased load within its designated area. In this case, the mRSU travels to the call point via the shortest route, the mathematical description of which is provided in Section 3.1. The two considered interaction schemes, described in the contributions above, point 2, represent the primary scenarios under which the simulation and evaluation of V2X system performance were conducted based on the parameters outlined above. Several assumptions were made during the development of the simulation model to simplify the system's structure:  
1. The current configuration of the model does not utilize C-V2X. 2. The traffic flow scheme is one-way, with only one lane per direction. 3. Traffic light regulation is absent. Traffic delays arise only due to emergency situations. 4. The influence of interference and noise on the signal due to real-world terrain architecture is not considered. Averaged characteristics are used in two signal attenuation model variants (Hata and 3 GPP). The simulation system is highly specialized and does not claim to instantly solve all problems within the considered class. However, as demonstrated below, the obtained results surpass those of known simulation systems across several parameters. Conducting numerical experiments using the author's simulation system (VANET 2.0.0) and the commercial tools described above, we obtained similar results for losses due to signal interference and noise ratio. This suggests that utilizing any suitable approach is acceptable for evaluating losses in the considered system configuration. The simulations were performed using the same initial dataset: the same map (Erlangen (Germany)) and the same amount of OBU and RSU. A comparative analysis of load characteristics, time, and resource consumption is presented in Table 2. Both simulation systems resulted in less than 1% loss.