## 4 Simulation of NDN Transport in V2X Scenarios
### Simulation Scenarios for V2X Communication
As already apparent from the fact that we include pedestrians, we foresee partially autonomous traffic. In addition to pedestrians, we assume that selected vehicles may be operated by humans. Furthermore, we want to emphasize the fact that some road users may not be able to communicate at all. We assume that the number and behavior (routes, behavior at traffic accidents,...) of the human-operated vehicles and vehicles that do not communicate must be well defined for simulation. In order to allow for safe traffic, special simulation use cases for these road users must be prepared. The last point of interest regarding infrastructure and road users are the destinations of all autonomously driving vehicles, as well as further simulation-relevant vehicle parameters (e.g., acceleration rate, deceleration rate, or turning circle). IncidentsAnother characterization category of V2X scenarios are incidents, such as traffic jams, traffic accidents, and blocked routes. These incidents are highly unpleasant for road users, as they reduce traffic flow. However, especially in urban environment, information about such incidents may lead to efficient change of driving routes. Furthermore, information on incidents increases road safety. Use casesTo fully characterize a V2X scenario, we need use cases, e.g., parking, changing lanes, behavior at intersections, behavior with approaching priority vehicles. At performance evaluation, we distinguish between traffic flow and communication evaluation. Examples for traffic flow evaluation are throughput in number of cars on a specific road point, average time to pass a road segment, or jam lengths in before bottlenecks, such as traffic lights, unmanaged intersections, or roundabouts. Examples for communication evaluation are interest satisfaction ratio, or delay. Example scenariosFour examples scenarios incorporating challenging communication aspects are:  
* _Several cars driving alongside each other on a highway with approaching priority vehicles._ This is a one-way traffic high-speed use case. The challenging networking aspect of this scenario is that on car has to switch lanes such that the priority vehicle is able to overtake. Information from the priority vehicle has to travel and be processed in driving direction faster than the vehicle is driving, and actions have to be taken until the priority vehicle reaches the two cars' geo-location. Additionally, measures have to be taken that assure the authenticity of the priority vehicle's messages. * _Turning left at a traffic light controlled intersection in an urban environment (buildings near the road) at a rainy day._ This scenario is especially challenging to simulate realistically. Here, the applied channel model is essential for a realistic simulation, as buildings near the road cause reflections of the electromagnetic waves and wet weather conditions alter the electro-magnetic properties of the various surfaces. * _Turning left at an unmanaged intersection. A rear-end-collision is blocking the turn-left lane five car lengths before the intersection._ This scenario covers an intersection where the lane which should be used in normal circumstances is blocked by a traffic incident. However, there is enough space for avoiding the accident and turning left. As in S1, the networking challenge is message authenticity as well as timeliness. * _Taking a roundabout exit with crossing pedestrians at this exit._ While recent literature covers intersections, we also propose to simulate other bottlenecks such as roundabouts. From a communication point of view, this scenario is interesting, as following cars can be warned of potentially crossing pedestrians that are in general not part of the communication network.