## 2 Related Work
This model and its validation is based on real world measurements using IEEE 802.11p/DSRC devices, where they estimate the effects of building and other obstacle influence on radio communications between vehicles. The proposal considers building geometry and sender/receiver positions, and its model relies on building outlines, which are commonly available in modern geodatabases as Open Street Maps [6]. Furthermore, to keep the model computationally inexpensive, it only considers the line of sight between sender and receiver. By using the idea of [3] to detect the blocking effect of a building in the LOS between sender and receiver, the authors propose a generic model extension which is built on well-known propagation models, as shown in equation (4), where \(P\) represents the transmission power or receiver power, \(G\) represents the antenna gains, and \(L\) reflects the loss effects during transmission. \[P_{r}[dBm]=P_{t}[dBm]+G_{t}[dB]+G_{r}[dB]-\sum L_{x}[dB] \tag{4}\]  
Figure 2: Detection of relevant building influence in the transmission process between nodes A and B. Red buildings are considered to have a relevant influence. We use a zone map of Barcelona, Spain. In order to include the influence of the obstacles in the LOS between sender and receiver, the Equation (4) was extended to get Equation (5),  
\[L_{obs}[dB]=\beta_{n}+\gamma d_{m} \tag{5}\]  
where \(L_{obs}\) captures the additional attenuation caused by an obstacle in the transmission process, based on the number of times \(n\) that the border of the obstacle is intersected by the LOS, and the total length \(d_{m}\) of this intersection. In Equation (5), \(\beta\) represents the attenuation caused by the outer wall of a building and \(\gamma\) is an approximation of the internal structure of a building. These parameters are used to adjust the model for managing the influence of different kinds of buildings when setting urban scenarios. In order to improve VANET simulation results, the authors of [7] design and implement a more realistic radio propagation model, called the U.K. model (New University Kangaku) on NCTUns 6.0. This model was specifically proposed for VANET simulations in Tokyo, which represents a highly-populated environment. The New U.K. model considers both the line-of-sight (LOS) and non-line-of-sight (NLOS) conditions in its equations to compute the path loss. For the LOS condition, the distance between two vehicles, \(d\), can be easily determined. In addition to the direct distance \(d\), the computation of the LOS, shown in Equation (6), path loss involves several other parameters, such as the transmitter's height \((h_{t})\), the receiver's height \((h_{r})\), the widths of the streets in the scenario (\(W_{s}\), \(W_{1}\), \(W_{2}\)), the brake distance point \((d_{b})\), and the frequency \(f\) in GHz. For NLOS path loss computation using Equation (7), \(d_{1}\) represents the distance between a vehicle (which can be either a transmitter or a receiver) and the intersection, and \(d_{2}\) represents the distance between another vehicle and such an intersection. The computation of the NLOS path loss also involves many parameters, such as the transmitter's height, the receiver's height, the brake point, and the frequency. Different from the LOS path loss computation, for the NLOS, the sum of \(d_{1}\) and \(d_{2}\) (\(d=d_{1}+d_{2}\)) is used as the distance between the transmitter and the receiver.