Page 141 - ITU Journal, Future and evolving technologies - Volume 1 (2020), Issue 1, Inaugural issue

ITU Journal on Future and Evolving Technologies, Volume 1 (2020), Issue 1

6G VISION: AN ULTRA-FLEXIBLE PERSPECTIVE

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Ahmet Yazar , Seda Doğan Tusha , Huseyin Arslan 1,2
1 Department of Electrical and Electronics Engineering, Istanbul Medipol University, Istanbul, 34810, Turkey
2 Department of Electrical Engineering, University of South Florida, Tampa, FL, 33620, USA

NOTE: Corresponding author: Ahmet Yazar (ayazar@medipol.edu.tr)

Abstract – The upcoming sixth generation (6G) communications systems are expected to support an unprecedented variety
of applications, pervading every aspect of human life. It is clearly not possible to fulfill the service requirements without
actualizing a plethora of flexible options pertaining to the key enabler technologies themselves. At that point, this work
presents an overview of the potential 6G key enablers from the flexibility perspective, categorizes them, and provides a general
framework to incorporate them in the future networks. Furthermore, the role of artificial intelligence and integrated sensing
and communications as key enablers of the presented framework is also discussed.
Keywords – 6G, adaptive, arti icial intelligence, cognitive radio, dynamic, lexibility, sensing.

1. INTRODUCTION
Following the successful standardization of the Fifth
Generation (5G) networks worldwide, academia and
industry have started to turn their attention to the next
generation of wireless communications networks [1].
At present, there are more than 100 research papers
regarding the Sixth Generation (6G) of wireless com-
munications. There is no doubt that new visions and
perspectives will continue to be developed in the coming
years. However, despite all these efforts, current litera- Fig. 1 – Flexibility terms.
ture lacks gathering the distinctive features of 6G under (OFDM) have provided lexibility in terms of multiplex-
a single broad umbrella. ing, rate adaptation and interference management via
the exploitation of different spreading factors and the
The evolution of cellular communications through dif- multidimensional resource utilization, respectively.
ferent generations from the Radio Access Technology
(RAT) perspective is shown in Table 1. The number of The introduction of various services with rich re-
capabilities for newer cellular generations increases as quirement sets under 5G has revealed the need for a
a result of the need to meet diversi ied requirements. lexible network that can simultaneously meet diverse
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Flexibility , where it is de ined as the capability of making requirements. 5G has given a start for lexible wireless
suitable choices out of available options depending on communications by the accommodation of different
the internal and external changes, of the communications technologies. To exemplify, the coexistence of multi-
systems eventually evolves with an increasing number numerology in a single frame has been adopted during
of new options. In this context, Fig. 2 provides a concise standardization meetings. In a given network, achieving
lexibility analysis for different generations of cellular lexibility is mainly dependent on three capabilities
communications considering the features in Table 1. 1) awareness, 2) availability of a rich set of technology
options, and 3) adaptation & optimization. On this basis,
The Second Generation (2G) systems have paved the way although the lexibility perspective has been broadened
for lexibility in communications systems by means of in 5G systems with respect to previous generations, the
multiple frequency reuse options, adaptive equalization, existing technology options are not enough to reach all
and dynamic channel allocation. The Third Generation the goals of 5G networks. Additionally, it is expected
(3G) and the Fourth Generation (4G) cellular systems that 6G networks will put further pressure on service
have incorporated voice communications with data com- providers due to emerging applications and use cases
munications. Additionally, Code Division Multiplexing corresponding to new sets of requirements. Therefore,
(CDMA) and Orthogonal Frequency Division Multiplexing 6G systems need to extend the current lexibility by
(1) exploring the awareness for the different aspects of
1 The other terms used interchangeably for lexibility are shown in Fig. 1. the whole communications network and environment

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