## 5 Application to Platoon Protection
### Problem Formulation  
In platoons, each vehicle can utilize V2V communication to obtain information about vehicles that are in non-line-of-sight (NLoS) points that cannot be detected by its sensors. This is also essential for all platooning vehicles to use the platoon leader's driving information. For our purpose, it is considerably difficult to define the platoon formation and the surrounding traffic in a completely generic manner. Thus in this paper, we consider the scenario as depicted in Figure 10, where the autonomous platooning and non-platooning vehicles move together on a road, and they are subjected to a roadside attack from \(K\). Since the platooning is dangerous to perform in urban roads, the highway environment is usually assumed. Figure 10 is the platooning scenario in the highway environment. Following the 3 GPP TR 36.885 (Annex A) suggests for evaluation scenarios [2], we used a straight road longer than 2 km. Unlike the 36.885 that suggests 2.5 s gap between vehicles that run at 70 km/h, however, all non-platoon vehicles in our paper try to keep at 80 km/h with 1 s gap (approximately 22 m) and platoon vehicles, 10 m.  
In this formulation, there are \(\gamma\) vehicle groups on a 10 km stretch of a lane. Each vehicle group is composed of \(\alpha+\beta\) vehicles, where \(\alpha\) and \(\beta\) are the numbers of platooning vehicles and non-platooning vehicles, respectively. It models the driving situation from the viewpoint of platoons where it is behind a non-platoon vehicle population in a lane. As the platoon uses a smaller inter-vehicle gap than non-platoon vehicles, the false position attack from \(K\) is a more grave safety threat to the platoon vehicles. As above, all vehicles exchange BSM at 23 dBm, but for whispers, we will assume here that they use the Tx power of 9 dBm, slightly higher than in the previous sections. As a result, \(d_{\text{W}}\) is 170 m in our simulation setting while BSM propagation dwindles in power till 600 m beyond which the packet delivery is hardly possible. Figure 10: Simulated platooning scenario. Let \(N_{j}^{i}\) be the \(i^{\text{th}}\) non-platooning vehicle of the \(j^{\text{th}}\) group, and \(P^{k}\) denote the \(k\)th platoon. For the string stability of the platoons, we model into the simulator the Rajamani controller Rajamani (2018) that computes the desired acceleration of each vehicle in the platoon. For this, we assume that the platoon vehicles receive the movement data of both the preceding vehicle and the platoon leader through V2V communication, whereas non-platoon vehicles receive only those of the preceding vehicle. We set the intra-platoon safety gap, namely the required minimum distance between two consecutive vehicles in the platoon, to 10 m as assumed in many works of literature. The length of a vehicle is 5 m, and the safety gap between non-platooning vehicles or between a non-platooning vehicle and the immediately following platoon leader is one second headway time at 80 km/h, which is approximately 22 m. Although presenting the case where collisions occur will obviously be more dramatic, we set the safety gap to a large value because we want to show that even if there is no collision, the attack can still affect the comfort and the efficiency of the vehicle traffic running with platoons. We assume that all platoon vehicles try to keep their speed at 80 km/h. In contrast, non-platoon vehicles can use higher speeds when it wants to close the gap with a preceding vehicle. The maximum acceleration and deceleration of both types of vehicles are assumed to be 3 m/s\({}^{2}\) and \(-5\) m/s\({}^{2}\), respectively [PERSON] _et al._ (2018). All vehicles can use their sensors to detect the obstacles within 150 m of the line-of-sight (LoS). Notice that \(N_{1}^{1}\) has no obstruction in front, so it can easily recognize obstacles in the front. However, the front view of its followers are blocked by the preceding vehicles, making it difficult to detect obstacles. An attacker \(K\) is situated at \(d_{W}\) from the roadside.