This talk provides an insight into the Fifth Generation of Cellular Communications (5G) and its future developments. It presents the current 5G transmission techniques and those expected in future developments. An introduction to the Sixth Generation of Cellular Communications (6G) is also made, as well as the expected associated transmission techniques. The insertion of 5G and 6G within the framework of the Fourth Industrial Revolution is discussed in this conference. Consisting of a paradigm shift, when compared to previous generations, 5G supports a myriad of new services based on the Internet of Things (IoT) and Vehicle to Vehicle Communications (V2V), supporting autonomous vehicles, Smart Cities, Smart Homes, remote surgeries, etc. While 5G plays an important role in the initial implementation of the 4th Industrial Revolution, 6G will address a number of new services, such as Virtual Reality, Augmented Reality, holographic services, advanced Internet of Things, wireless brain-computer interaction and higher speed mobility.

5G communications raise a set of security issues that are important to identify and find ways to mitigate.The extremely high number of IoT devices expected to be interconnected over 5G networks may not be secure enough, acting as an undesired gateway to this network.On the other hand, the new potential of the 5G network, namely the possibility of direct mode of operation, can be viewed as an alternative to TETRA system used by European security forces and services, which still consists of a second-generation system, with low capacities.Finally, the subsequent use of the data obtained by the 5G manufacturers also needs to be analyzed.