 Edificio Los Tejos, Pamplona, Navarra, Spain e-mail: francisco.falcone@unavarra.es © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 M. A. Matin (ed.), A Glimpse Beyond 5G in Wireless Networks, Signals and Communication Technology, https://doi.org/10.1007/978-3-031-13786-0_7 L. Azpilicueta et al. cations up to date. Nonetheless, at the early phase, the network deployments do not implement all the capabilities defined for 5G New Radio 5G NR) network. Network optimization and standardization is an uncompleted process, in which researchers have continued to work in parallel to identify enabling factors and promising topics beyond the present 5G situation that will unavoidably lead to the next generation of wireless communication system. This phase of research stage conforms beyond 5G (B5G), and the efforts will lay the definition of the sixth generation (6G). 6G will likely combine trends derived from 5G and B5G research phases. Several white papers [1-8] and consortiums [9-11] describe basically the same idea as presented here. The evolution of 5G/B5G/6G accepts the following timelines or roadmap [12]: 5G phase 1: up to 2020 with the spectrum allocated below 6 GHz in 2015 World Radiocommunication Conference (WRC-15), [13]. It is usually referred to as simply 5G. 5G phase 2: likely extending to 2030 with the spectrum above 6 GHz recently allocated in 2019 World Radiocommunication Conference (WRC-19) [14], usually referred as B5G. Post 5G phase 2: beyond 2030, and likely laying 6G if standardization is reached. B5G and 6G networks may then be defined as the next generation of mobile communication systems with characteristic features that will contribute to the Sustainable Development Goals (SDG), such as ultralow power consumption, ultra-security and reliability, autonomy, and scalability, jointly to optimize 5G performance in three specific service cases: enhanced mobile broadband (eMBB) for ultrafast speed and capacity (up to 10 Gbps over the air transmission rate), ultra- reliable lo