The second phase is to run purely networks that fully comply with the upcoming specifications for 5G standalone (SA) networks. These allow full deployment of other applications for mMTC and URLLC. Specifications are currently being finalised and technology tested and further developed, which is related to the need to invest in new central operator systems as well as massive investments in the network itself. At this stage, 5G networks will be completely independent of 4G. The achievement of this phase and the implementation deadlines cannot be easily estimated, and it is reported that this will happen between 2020 and 2021 and onwards, following the completion of standardisation. In order to enable a high data rate, reduce latency and increase the number of terminal devices, 5G networks must employ several new technologies and procedures, and be based on a different architecture than the current networks. 2.3 Main differences between 5G networks and existing networks The first significant change compared to existing networks is the use of new parts of the radio spectrum. In Europe, 5G networks will use new parts of the radio spectrum: Current bands with frequencies below 1 GHz are accessed by the 700 MHz band, the centimetre band 3.4 to 3.8 GHz and the millimetre band 26 GHz. Each of these newly used frequency bands has different characteristics that will serve aspects of different parts of the 5G network. - - - Band around 700 MHz: Low frequencies, bandwidth limits the amount of data transmitted per time unit, thus limiting the maximum attainable data rates and showing high latency. Wave propagation is burdened by relatively low attenuation, so communication over longer distances is energy efficient and also highly reliable. It is therefore ideal for IoT devices that do not need low latency or for larger data flows such as IoT, or to cover larger areas where there is no requirement to serve a large number of users simultaneously. Band above 3.4 GHz: Most of the current development of 5G networks and the launch of the first networks operate in the 3.4-3.8 GHz band. The main news is that the wavelength allows the creation of multi-element antennas of acceptable dimensions and through them so-called beaming (beaming forming). This means that antennas with this technology can direct the signal to a specific user, thus allowing significantly more efficient network operation. However, the range is generally smaller than in the previous case. 26 GHz band: Represents the first utilisation of millimetre waves in mobile networks. Due to the wide bandwidth, millimetre waves allow the transmission of huge amounts of data (gigabits) at very low latency to a large number of users. However, these features are balanced by a very short range. Radio waves only operate in the range of hundreds of metres and the signal struggles to pass not only through walls, but also through vegetation and even heavy rain. In order to achieve stable coverage, the antenna must be installed, for example, on public lighting poles. This is very demanding not only in itself, but also in terms of connecting each individual antenna to the optical network. Such a large-scale construction of antennas can also encounter resistance from citizens. They are usually sceptical about the construction of new radio communication works and 5G networks are already the target of hoaxes and conspiracy theories. Consequently, the construction of microwave infrastructure has not been carried out to a great extent, even though it would bring the most significant benefits for the common user and industrial applications. The second change compared to the current networks is the emphasis on the best utilisation of optical networks in the case of backhaul connectivity. Optical networks are not limited by bandwidth and represent a key transmission technology due to the dynamic developments in electronic communications. This principle also exists to a lesser extent in current networks – the connection of base stations is often already realised by optical or microwave links. 5G networks take the need for fibre optic connections even further. The reason for this effort is the physical limitations of radio waves affecting both the volume of 7