## Appendix A
Hence, it is expected that the total number of devices connected by global mobile communications networks will surpass 100 billion by 2030. Moreover, the popularity of ultra-high resolution and large screens as well as the increasing number of high-performance smart devices such as smartphones and tablets, together with the growth of mobile subscriptions will dramatically increase the mobile traffic volume consumed by each user. [272] estimates that each subscriber will consume 5.3 GB, 39.4 GB, and 257.1 GB of data traffic per month in average in 2020, 2025, and 2030, respectively. Beyond the major market and mobile traffic growth drivers, innovative wireless technologies will be a critical component in this development, which opens up new applications. In this frame, ICT are advancing in the following key areas and technologies [270; 271; 272; 273; 274; 275; 276; 277; 278; 279; 2]:  
* Wireless communication platforms and infrastructure such as 5G (IMT-2020) systems and beyond, High-Throughput Satellites (HTS) in geostationary (GEO) or Medium Earth Orbits (MEOs), Low Earth Orbit (LEO) satellite mega-constellations, High Altitude Platforms (HAPS) and future hybrid terrestrial-satellite networks will enable new forms of connectivity for the delivery of broadband services and the possibility of being always connected. Their evolution, key technology drivers, the markets, and perspectives are summarized in [2]. * Spectrum resources: in order to cope with the higher traffic capacity and higher typical user data rate in 5G and in mobile satellite networks, considerably more spectrum is required than currently available. Spectrum has been in the past and will be also in the future one of the most valuable resources for mobile communications. Therefore, agencies and standardization organizations worldwide aim for international harmonized spectrum and full-spectrum access, especially above 6 GHz. Hence, beyond the sub-6 GHz bands for 5G in Europe 3.4-3.8 GHz, USA 3.1-3.55 GHz and 3.7-4.2 GHz, Japan 3.6-4.2 GHz and 4.4-4.9 GHz and China 3.3-3.6 GHz, 4.4-4.5 GHz and 4.8-4.99 GHz for 5G Phase I, frequency bands in the mm-wave range are already foreseen for 5G Phase II: in Europe 24.25-27.5 GHz and 31.8-33.4 GHz, USA 27.5-28.35 GHz and 37-40 GHz, Japan 27.5-29.5 GHz, 4.4-4.9 GHz, China 24.75-27.5 GHz, South Korea 26.5-29.5 GHz [275]. The technical feasibility of radio interface technology and systems operating in these frequency bands, taking into account propagation characteristics, antenna technology, active and passive components, physical layers, and medium access control design as well as deployment architectures, are carried out by simulations and performance tests and trials. Some are published in [271; 276; 277; 278; 279]. In Europe, the European Telecommunications Standards Institute (ETSI) is working to facilitate the use of the E-Band from 71-76 GHz and 81-86 GHz, and in the future, on the channelization of the W-band from 92 to 114.5 GHz and the D-band from 130 to 174.8 GHz for large-volume (high capacity) backhaul and front-haul systems as well as for innovative solutions for fixed broadband access [279]. Most of the HTS in GEO and MEO make efficient use of both, Ku-band and Ka-band (e.g., O3b downlink 17.7-20.2 GHz, uplink 27.5-30 GHz). Low Earth Orbit (LEO) high-throughput satellite constellations also aiming to operate in the Ku-band and Ka-band. * Network architectures: while previous generations of wireless networks are characterized by fixed radio parameters and spectrum blocks, software advances, and other complementary technologies will increase the flexibility, configurability, and efficiency of services such as cloud-radio access network (RAN), heterogeneous networks, network slicing, and network function virtualization (NFV) [270; 271; 280; 281]. * Integrated access node and backhaul design will enable the ultra-dense networking of radio nodes, where such nodes will need to access and self-organize available spectrum blocks for both access and backhauling.