nfrastructure Fig. 7.6 Typical multipath channel for wireless communications For UAVs, channel propagation measurements are essential since the scenarios involved are more complex than the classical planar point of view for cellular networks. Multipath environment is different and needs to be assessed in many different situations in urban and suburban environments. The use of multiple-input multiple-output antennas in UAVs is another challenge since the traditional radiation patterns can now be modified with beamforming techniques, but with a different advantage, UAVs can "accommodate" the beams not only by using signal processing algorithms for beamforming but also with physically changing positions that could improve communications [47]. There have been network architectures proposed for 5G [46]; however, archi- tectures that consider V2X communications have not been widely developed. In [48], the authors propose an architecture for V2X communications in 5G that not only tries to deliver connectivity with reliability but also tries to solve security and privacy issues. It considers a network edge that works with the 5G infrastructure to deliver services and applications. Such network edge is connected to V2X application servers via a core network that is software based for flexibility. Even though vehicles can form VANETs, communication through the architecture is carried out from/to the 5G infrastructure. The V2X concept comprehends the classic V2I and V2V, and two more types are added, the vehicle to pedestrian (V2P) used for collision avoidance and driver alerts and the vehicle to network (V2N) where applications are in dedicated servers to which vehicles can connect for services such as traffic and navigation of weather. It is also important to include cooperation to achieve efficiency in the network. From the perspective of problems needed to be addressed, it is important to have models validated with measurements and simulations in order to propose solutions for problems such as interference. As the numbe