5G Wireless Technologies (Iet Telecommunications)

Book Preface

‘‘From the smallest personal items to the largest continents, everything, everywhere will be digitally connected, and responsive to our wants and likes’’ is a typical vision for the future of communication networks as stated in ‘‘The World in 2025: 10 Predictions of Innovation’’ (Thomson Reuters). In particular, wireless communications are expected to dominate everything, everywhere, and transform everyday life, mainly by means of revolutionary fifth-generation (5G) technologies characterized by concepts such as: cell-less architectures, massive spatial processing, tactile response times, big data processing and virtualization, to name a few. Toward this end, research, performance evaluation, experimentation, and standardization activities have started [1,2]: international industry-academia consortia (METIS2020, IWPC, 5G Korea), public–private partnership associations (5G-PPP), regulatory authorities (ITU-R WP5D), and operators fora (NGMN) have recently focused their attention on setting the requirements, exploring the system concept characteristics, and investigating the enabling technologies for 5G [3].

Wireless evolution has come a long way over the last 40 years, starting from a technology-centric all the way to a technology transparent future, shifting the focus of innovation from components and radio transceiver technologies (e.g., turbo coding, MIMO) to resource allocation and interference management (e.g., CDMA, OFDMA, Coordinated Multipoint transmission/reception-CoMP) and, finally, to user-centric and device-driven communications, in the ‘‘internet of everything.’’ Accelerated by the dramatic impact of applications of the kinds of social networking, the center of gravity for 5G will be shifted further to application-driven connectivity (transparently deployed over technologies, infrastructures, users, and devices), which will be mainly enabled by means of dense access/serving node deployments and exploitation of proximal communications, concepts that are typically referred to as network densification [4]. In contrast to previous cellular evolution steps, which were mainly driven by increasing system bandwidth and improving (multi-user) spectral efficiency, network densification is expected to be the cornerstone of future wireless networks. Even though network densification was also considered in past cellular generations, it was used only as an ‘‘add-on’’ measure for locally coping with heavily loaded parts of the system and not as a fundamental, large-scale design/system concept.

Toward realizing the ambitious goals set for 5G, the density of access/serving nodes is expected to increase up to the point where it is comparable to or even much higher than the (also increasing) density of user equipments (UEs) [5], thus introducing the ultra-dense network (UDN) paradigm. Realization of such a disruptive network topology, with respect to the evolution path of previous cellular generations, will be achieved by utilizing, in addition to densified traditional access nodes (ANs) such as small cells, user deployed ANs (e.g., Wi-Fi, femtocells), as well as ‘‘infrastructure prosumer’’ UEs, i.e., (mobile) devices with computational and storage capabilities allowing them to act as infrastructure ANs (Figure 1.1).