Page 144 - ITU Journal, Future and evolving technologies - Volume 1 (2020), Issue 1, Inaugural issue
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ITU Journal on Future and Evolving Technologies, Volume 1 (2020), Issue 1




                                           Potential
                             Potential                  Focusing on  Focusing on   An Inclusive  The Future of
                            Applications  Service Types  the Key       the Key     Perspective    A Speci ic
                  Ref.                       and
                            and Key Re-                 Enablers in   Enablers in   for the Key  Technology
                            quirements    Application    General        Detail      Enablers      or Concept
                                            Groups
               This work        3             3             3                          3
                  [1]           3             3                           3
                  [3]           3                                         3
                 [4–13]         3             3             3
                  [14]          3             3
                [15–21]         3                           3
                [22,23]         3
                [24–28]         3             3                                                      3
                [29–39]         3                                                                    3
                [40–83]                                                                              3
                                           Table 2 – Scopes of 6G publications in the literature.


          Human-Centric Services (HCS), Multi-Purpose Services  Although technologies placed in different categories can
          (MPS) in [7]. As it is seen from the names, some of the  have overlapped regions, the given categorization dif-
          service types (e.g., SuRLLC, uHSLLC, reliable eMMB,  ferentiates these technologies regarding their  lexibility
          MBRLLC, mURLLC, MPS) try to be more inclusive than   aspects.
          the 5G service types to serve target applications. It is also
          possible to see more speci ic service types (e.g., BigCom,  Table 3 provides a summary of the example  lexibility op-
          3D-InteCom, UCDC, LDHMC, ELPC, HCS) in comparison    tions achieved by the different technologies. It is worthy
          with 5G.                                             to emphasize that the different key enablers have their
                                                               own impact on the overall  lexibility of the system. Ulti-
          The aforementioned applications/services envisioned for  mately all of them combine together to provide the com-
          6G illustrates the expected richness of its requirements.  plete infrastructure capable of realizing the  lexible 6G vi-
          These diverse requirements necessitate an ultra- lexible  sion that we aspire to achieve.
          perspective for the incorporation of key enabler technolo-
          gies and concepts, described below, in future networks.  3.1 Flexible Multi-Band Utilization

          3.  ULTRA-FLEXIBLE PERSPECTIVE FOR 6G                The inclination of communications technologies towards
                                                               high-frequency bands becomes more appealing due to
          In this section, an inclusive categorization of promising  the increased system capacity and throughput demands
          key enablers is presented for 6G communications and  of cellular users. Furthermore,  lexible usage of available
          their example  lexibility aspects are discussed in detail.  frequency bands, depending on the user and service
          Then, several  lexibility challenges are provided for 6G.  requirements, is envisioned to be an inherent character-
          Key enabler categories and their related subcategories  istic of future wireless networks [74].
          are shown in Fig. 4. Many of these technologies are
          either super icially treated or not studied during 5G  The millimeter Wave (mmWave) spectrum is starting
          standardizations, such as Integrated Sensing and Com-  to be exploited in 5G. It provides new bene its, such as
          munications (ISAC) and intelligent communications.   multi-gigabit data rates and reduced interference, how-
                                                               ever, the use of mmWave bands in 5G is limited by the
                          APPLICATIONS                         current International Mobile Telecommunications (IMT)
              Each service type                                regulations. In World Radiocommunication Conference
                has unique                  Applications are   2019 (WRC-19), additional 17.25 GHz of spectrum is
              requirement sets                mapped to
             for application groups          requirements      identi ied for IMT, where only 1.9 GHz of bandwidth
                                                               was available before [85]. Therefore, it is expected that
                                                               spectrum availability in these bands and consequently
                                                               its  lexible utilization will increase during the upcoming
            SERVICE TYPES             REQUIREMENTS             years [42]. Moreover, beyond 52.6 GHz communications
                                                               is one of the agenda items for 3GPP Release 17 [86].
                         Requirements are grouped
                          under the service types
                                                               Frequency bands from 100 GHz to 3 THz are envisioned
          Fig. 3 – A basic relationship between the applications, requirements,  as a candidate spectrum for 6G communications [40]. If
          and service types.                                   THz communications is employed in 6G, it promises a way





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