Shaping Future 6G Networks. Группа авторов

toward a more digital world. Each generation has featured comprehensive cellular network architecture, including radio access technology, access and core network routing, and a set of associated services (such as authentication and access control, mobility management, data transfer, or voice and messaging services). The 2nd generation (2G) brought the first fully digital mobility solution, giving birth to the mobile phone as a portable personal device and to the rise of text messaging. The 3rd and 4th generations (3G and 4G) introduced the use of multimedia services in mobility and enabled the advent of the iPhone and all the digital industry and services relying on smartphones (e.g. mobile Internet, applications, and marketplaces). The 5th generation (5G) should accompany the emergence of a nest of communicating objects, along with new devices enabling augmented reality, for both the consumer and the enterprise market. The path is already drawn for the deployment of 5G non‐standalone (5G NSA) networks starting from 2019 (where only the radio part of 5G is deployed as a new access network) and then of standalone 5G networks (5G SA) starting from 2023 (where a new 5G core network is also deployed).

It may seem strange to start shaping the 6th generation (6G) of mobile communication networks while 5G is just starting to be deployed around the globe – given we are still witnessing a big gap between the high expectations surrounding the capabilities of new 5G networks and the functional limitations of initial 5G products and solutions. Moreover, 5G is quite different from previous mobile network generations in regard to its technological innovations, complexity, and targeted broad spectrum of applications, ranging from energy‐efficient massive Internet of Things (IoT) and massive broadband multimedia to low‐latency communication. In addition, every new network generation (including 5G) must strike a compromise between backward compatibility, disruption, innovation, and ability to enable completely new applications. This complexity takes time for the telecom industry to fully master.

      In this context, should we focus on building 6G or first draw the lessons from 5G deployments and use cases? Every new network generation deserves around 10 years of research. The first generation of digital cellular network (2G) was commercially launched in 1991, followed by 3G in 2001, 4G in 2009, and 5G in 2019. Thus, now is the time to shape 6G, with a target launch in 2028–2030. Research on 6G effectively started around the globe in 2020.

1.2 Early Directions for Shaping 6G

      1.2.1 Future Services

      So, what will 6G look like? Will there be a killer application? This book discusses some future possible use cases, such as teleporting and digital twin; smart and autonomous transportation; digital services in cities, farming, and warehousing targeting environmental monitoring, traffic control, and management automation; or a fully digital commerce and payments experience, featuring resolution digital signage with facial recognition in retail, and augmented reality/virtual reality (AR/VR)‐enabled e‐commerce. Some of those use cases were also discussed for 5G. Before we can clearly assess the use cases, though, we have to see what emerges in the next few years, as 5G evolves and gains acceptance in different vertical markets.

      Do we need a predefined mind‐blowing application driver before shaping 6G architecture? That was not the case for previous generations, and uses like text messaging (for 2G) and smartphone‐based mobile Internet (for 3G and 4G) emerged without strong support from the telco industry. So 6G should probably be seen more as the infrastructure on which innovative actors will build new digital services. Modularity, flexibility, and openness are key requirements.

      1.2.2 Moving from 5G to 6G

      5G is already a software‐based end‐to‐end communication system, allowing the addition of new access and backhaul networks as well as new control and management functionalities and virtual network functions (VNFs). So, should the industry start building a new generation instead of perfecting the existing one? It is likely that similar to previous even network generations (i.e. 2G and 4G), which perfected preceding network generations, 6G will finally deliver what was promised years ago for 5G. Many research topics currently performed in the context of 5G evolution will also pave the way toward 6G. Therefore, most researchers may consider the need for 5G evolution as the driving force toward 6G. In fact, at the end of the decade, which represents the typical life span of a mobile generation to deliver innovations, 5G may have become an open extensible and customizable communications platform, representing a toolbox to build public as well as private mobile communication networks for any kind of vertical application domain.

While it might be realistic to assume that 6G will be an evolution of 5G, there are also voices who propose that 6G should be much more disruptive and revolutionary, due to the exploitation of new enabling technologies. New concepts like the post‐Shannon theory and the use of emerging quantum computing technologies are just two examples of this line of thinking. To provide a scientific look beyond the rim, we address one of these topics at the end of the book (Chapter 16).

      Moreover, while defining a new generation of cellular system every 10 years has a lot of advantages, as it enables deployment of a consistent set of features and technologies where all elements have been designed and packaged to work together, this model comes with a major drawback: the various components and technologies are tightly linked. It is therefore difficult to redesign one piece of the puzzle without touching the others. In a world being eaten by software, this may appear a bit old‐fashioned, as modern software engineering relies on decomposing systems into loosely coupled entities. So, 6G could also be the opportunity to extend 5G into an even more modular framework where various parties can more easily add different components, keeping in mind the necessary trade‐off among openness, reliability, and security, in order to achieve a highly trustworthy architecture. This would imply breaking or at least weakening the link between the radio access part and the core network part in the definition of this new generation, inspired perhaps by the idea of other wireless technologies, relying on unlicensed spectrums, such as Wi‐Fi and LoRaWAN. Finally, 6G is also an opportunity to continue decreasing operational costs, using artificial intelligence (AI) and machine learning (ML) to extend automated network planning, deployment, and operation; the ultimate target being to enable real self‐organizing networks.

      1.2.3 Renewed Value Chain and Collaborations

      Besides technologies and services, the business models of mobile communication networks are also evolving and will continue to evolve rapidly in the forthcoming years. Due to the ongoing fixed‐mobile network convergence and Information and Communication Technology (ICT) convergence, future communications will be tightly integrated in enterprise applications. The global rise of 5G campus networks should be considered just the start toward 5G enterprise networking and the emergence of new business models and ecosystems. This also raises questions on the role of international standards and rise of open software stacks paving the way toward a new telecommunications ecosystem, in which virtualized network functions from different developers and providers can be dynamically orchestrated and integrated in a secure, reliable, and energy‐efficient manner. The work on OpenRAN and the involvement of new players (e.g. Facebook Magma) can be considered a foretaste of these changes in the value chain of the entire mobile industry.

      In mobile technologies, as in many other areas, geopolitical factors might mean a more fragmented future for the world. In their desire for digital sovereignty, different governments push national academic and industry researchers to generate as many intellectual property rights as possible while shaping 6G. Prefaced by insightful tech leaders from America, Asia, and Europe, with authors from all around the world, this book is an attempt to promote the collaborative approach used to enable academic and industry players with different interests to work together to shape a common future.

With this book, we aim to provide students, researchers, senior executives, managers, and technical leaders with a snapshot of current international thinking on the major 6G research aspects. Similar to 5G, 6G also represents an aggregation of different technology innovations into an overall complex system architecture. We do not have the ambition to catch every technology trend, but we believe that we are quite comprehensive with our present collection of expert views in 2021.