Page 143 - 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




                     Flexibility

                                                                                 Infancy Stage of  Evolved Stage of
                      Infancy Stage of  Evolved Stage of  Infancy Stage of  Evolved Stage of  Flexible
                         Cellular       Cellular      High Speed    High Speed                     Flexible
                      Communications  Communications  Data Rates    Data Rates   Communications   Communications
                                                                                    Platform       Platform

                                                                                 Only Essential Rules   Only Essential Rules
                       Standard Defined -  Standard Defined -  Standard Defined -  Standard Defined -
            Transmitter                                                          Standard Defined -  Standard Defined -
                        No Flexibility  Low Flexibility  Medium Flexibility  High Flexibility
                                                                                 Very High Flexibility  Ultra Flexibility
             Channel      Random         Random        Random         Random        Random        Controlled
                                                                                 Intentionally Created  Intentionally Created
            Interference  Avoided        Avoided      Controlled     Controlled
                                                                                  and Controlled  and Controlled
             Receiver   No Flexibility  Low Flexibility  Medium Flexibility  High Flexibility  Very High Flexibility  Ultra Flexibility

                                                                                                  Generations
                          1G            2G             3G             4G            5G             6G

                                  Fig. 2 – Flexibility analysis of the previous generations and 6G communications.


          quirements, and service types. Flexibility discussions on  sory Virtual Reality (VR) and Augmented Reality (AR),
          the potential 6G key enablers are provided under a unique  holographic conferencing, virtual education, virtual
          categorization rather than giving different details of these  tourism, smart city, smart home, smart clothes, disaster
          enablers in Section 3. The scope of Section 3 is limited  and emergency management, and work-from-anywhere.
          to example  lexibility aspects for the potential 6G key en-  This list can be longer with more applications in the up-
          ablers. Next, a framework is proposed to increase inter-  coming years. Most of the aforementioned applications
          operability of the 6G enablers in Section 4. Finally, con-  were originally envisioned for 5G, however, they could
          clusions are drawn with several open issues in Section 5.  not be practically realized. Therefore, it makes sense to
                                                               address them  irst while developing the 6G networks.
          2.  A BRIEF OVERVIEW: FORECASTS ON 6G
                                                               General wireless communications requirements for the
          Identi ication of the future applications, requirements  given application examples can be de ined as: high data
          and possible service types is one of the primary objectives  rate, high throughput, high capacity, high reliability,
          of the initial 6G research studies. Fig. 3 illustrates the  low latency, high mobility, high security, low complex-
          basic relationship between these components. Mapping  ity, high connectivity, long battery life, low cost, wide
          the potential future applications to the several require-  coverage, and more.  The importance and priority of
          ments with different priorities is accepted as a  irst step  the requirements may change under different cases.
          in general. Next, these requirements are grouped under  Moreover, higher levels of performances need to be
          the service types in a reasonable manner. At the  inal  obtained in next generation systems while meeting the
          stage, service types have unique requirement sets for the  related requirements.
          related application groups. In 5G systems, applications
          are considered under three service types including   Since the requirement diversity is continuously increas-
          enhanced Mobile BroadBand (eMBB), Ultra-Reliable and  ing, more sophisticated service types are expected for
          Low-Latency Communications (URLLC), and massive      6G. Candidate service types are constituted by grouping
          Machine-Type Communications (mMTC) [84].  Among      applications with similar requirements.  Examples 2
          these, eMBB applications prioritize high throughput, ca-  can be given as Big Communications (BigCom), se-
          pacity and spectral ef iciency; mMTC prioritizes energy  cure uRLLC (SuRLLC), Three-Dimensional Integrated
          ef iciency and massive connectivity while URLLC requires  Communications (3D-InteCom), Unconventional Data
          high reliability and low latency. For 6G systems, some  Communications (UCDC) in [11]; ultra-High-Speed-with-
          of the initial studies inherently analyze the relations  Low-Latency Communications (uHSLLC) in [4]; Long-
          between the future applications and prioritized require-  Distance and High-Mobility Communications (LDHMC),
          ments to propose candidate service types [1,3–38].   Extremely Low-Power Communications (ELPC) in [5];
                                                               reliable eMBB; Mobile Broadband Reliable Low Latency
          The following list exempli ies potential 6G applications:  Communication (MBRLLC), massive URLLC (mURLLC),
          drone and Unmanned Aerial Vehicle (UAV) networks,
          drone taxi, fully automated Vehicle-to-Everything (V2X),  2 Comprehensive discussions on these potential service types can be
          remote surgery, health monitoring, e-health, fully sen-  found in the given references.





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