# Priority-Driven Resource Allocation with Reuse for Platooning in 5G Vehicular Network
## 4 System Modeling and Resource Allocation Algorithm
### System Model
Therefore, resource reuse for general vehicles is performed with the aim of minimizing interference with resource-allocated vehicles. To facilitate this, the reusability of a resource is determined based on the distance between resource-allocated vehicles, and resources may be reused by vehicles separated by a distance greater than a predetermined threshold. This threshold is defined as the resource reuse distance. In this paper, the resource reuse distance is calculated by applying the method proposed by [PERSON] et al., which calculates the perceived distance and reuse distance based on the SINR conditions in vehicle-to-vehicle communication [PERSON] et al. (2018). The resource reuse distance, or the minimum distance between vehicles using the same resource block without causing significant interference, is calculated by considering the perceived distance between vehicles and the interference generated when two vehicles share the same time-frequency resource block. [PERSON] et al. 's method accounts for various parameters, including path loss, transmission power, antenna gain, and noise power, to calculate the maximum allowable reuse distance while maintaining an acceptable SINR threshold for reliable communication. The key parameters in the model include the path loss factor, the transmission power of the vehicles, the antenna gain, and the noise power in the system. The path loss model accounts for the attenuation of the signal as the distance between vehicles increases, while the antenna gain factors in the directional characteristics of the antennas used by the vehicles. The noise power is calculated based on the environmental conditions and the operating frequency of the system. The base station can indirectly infer the destination address of a packet when allocating resources for platoon vehicles, unlike general vehicles. This inference is supported by the exchange of control information during the Radio Resource Control (RRC) reconfiguration process, where the base station can receive QoS requirements, logical channel configurations, and priority settings that are specific to platoon communications ([PERSON] et al., 2016; [PERSON] et al., 2018). A platoon vehicle operating under a distributed communication model periodically transmits packets to the next platoon vehicle. In this process, specific QoS characteristics, such as low latency and high reliability required for platoon safety and coordination, allow the base station to deduce that the next packet is intended for the following vehicle in the platoon. From this analysis, the base station can infer that the destination of the packet is the next vehicle in the platoon. Consequently, the base station can calculate interference and channel gain for platoon vehicles transmitting packets to the next platoon vehicle, particularly when using the same resource block. Resource reuse is then determined by calculating the Signal-to-Interference-plus-Noise-Ratio (SINR), which quantifies the interference level between vehicles. SINR is defined as the ratio of the signal power received by the vehicle to the interference and noise power caused by other vehicles, and it is calculated using the following equation:  
\[\gamma_{ijk}^{(j)}=\frac{P_{0}h_{ijk}^{(j)}}{N_{0}+\sum_{r^{\prime}\
eq i}x_{ rj}P_{0}h_{r^{\prime}k}^{(j)}} \tag{4}\]  
In this formula, \(x_{i,j}\) is a binary variable that indicates whether vehicle \(i\) is using resource block \(j\); it is set to 1 if the resource block is utilized and 0 otherwise. \(P_{0}\) represents the transmission power of the vehicle, and \(h_{i,k}^{(j)}\) denotes the channel gain between vehicle \(i\) and its receiving vehicle \(k\) for resource block \(j\). This gain reflects the quality of the wireless channel between the two vehicles, which depends on factors such as distance and environmental conditions. \(N_{0}\) represents the noise power at the receiver, which includes both thermal noise and environmental noise, affecting the reception of signals.