Page 31 - ITU Journal Future and evolving technologies Volume 2 (2021), Issue 6 – Wireless communication systems in beyond 5G era

ITU Journal on Future and Evolving Technologies, Volume 2 (2021), Issue 6

6G network infrastructure. On the other hand, the tech‐ satellite‐based C‐RAN. However, these choices are suit‐
nical design and development of TaHiL under 6G infras‐ able for connectivity in remote regions (which is the use
tructure will also be a test bench for the technologies and case in [106]) but in various areas these bands may inter‐
paradigms that are pillars for the realisation of digital fere with terrestrial IEEE 802.11‐based, industrial, scien‐
twins. As previously explained in Section 4, digital twins ti ic, and medical services.
will have several characteristics in common with general
haptic communications and, speci ically, with the TaHiL. Future 6G networks aims to go beyond the enhancement
In fact, digital twins will require an always‐ON feedback of terrestrial services, with the support of non‐terrestrial
loop between the virtual and real twins [43]. Moreover, networks. With 6G a new ambition has arisen. New multi‐
they will empower and extend the haptic data used within dimensional mobility services will enable end users and
machines moving in the three‐dimensional (3D) space,
the TaHiL to more general universal kind of data, which
being able to access (on demand) to connectivity and in‐
can fully convey and project the ’natural’ reality of enti‐
telligence support. Therefore with 6G, KPI on localisation
ties into the virtual reality.
precision and uniform user experience will be speci ically
de ined for terrestrial services and for services in the 3D
5.4 The uni ication of terrestrial, aerial, and
space [60]. Fig. 11 depicts an example of a 6G 3D scenario
satellite networks to provide coverage in rural and remote areas. The UAV
swarms perform operations limited to the physical layer,
Next, 6G will also have to inally satisfy the promises re‐ the so‐called Distributed Unit (DU), in order to maximise
garding the seamless integration of terrestrial, aerial, and the battery lifetime and operations. This means that con‐
space networks. This promise somehow started during stellations of Low Earth Orbit (LEO) nanosatellites will be
LTE [11], went on during 5G, and now it has been for‐ deployed to host the MEC, providing computing resources
warded to 6G (see the 6G KPI in Section 4). We believe for the virtualised RAN and the Centralised Unit (CU). Ac‐
that, for 6G, now can be the perfect convergence of fac‐ cording to what has been previously mentioned regarding
tors and circumstances to make this ’dream’ coming true. anticipatory networking, the 6G CU is going to be intelli‐
The maturity, low cost and easiness to launch and de‐ gent. In general, intelligent agents will be hosted in the
ploy satellite platforms (e.g. the case of nanosatellites), nanosatellites to perform functions for lower‐latency ver‐
and the amount of interest and investments on space, to‐ ticals. Next, the core network will be both terrestrial and
gether with the real need of reliable/seamless coverage orbital. Medium Earth Orbit (MEO) and High Earth Orbit
and lower latency, can be the perfect match to realise this (HEO) satellites will realise distributed orbital data cen‐
promise in 6G.
tres, providing computing for micro‐services and intelli‐
gent agents requiring higher computational resources. A
big open challenge will be the establishment, control, and
MS MS
MEO/HEO AG AG maintenance of micro‐service/agents chains in such com‐
nanosatellite
constellation plex network infrastructure. Moreover, the realisation of
(core)
distributed data centres in satellite constellations for 6G
MS MS 3D networks will also require signi icant investigation. In
LEO MS AG AG MS
AG
nanosatellite AG CU CU CU fact, satellites have power and time constraints (they use
constellation CU MS
(edge) AG solar power and provide coverage for a limited amount of
time).
UAV swarm
DU DU Terrestrial core
DU DU
5.5 The role of intelligence in 6G
Next, as already mentioned above while discussing la‐
Fig. 11 – 6G three‐dimensional architecture for coverage of rural and re‐
mote areas. Swarms of UAVs represent the base stations/access points tency, intelligence – AI and ML – for 6G can be the same
hosting the Distributed Units (DUs) with the physical layer operations. as softwarization and computing for 5G. As written in Sec‐
Low Earth Orbit (LEO) constellations of nanosatellites represent the tion 2.2, the original research and standardization efforts
edge, in which Centralised Units (CUs) are hosted. Moreover, this LEO
edge can also host micro‐services (MS) and agents (AG), which perform of Internet Engineering Task Force (IETF) and ETSI were
any softwarized functionality or service. The yellow colour indicate that absorbed and merged into the vision and standardiza‐
the service/function is intelligent. The core network can either be im‐ tion of 5G wireless cellular networks, which had subse‐
plemented in Medium Earth Orbit (MEO) or High Earth Orbit (HEO), or quently started. The work of the ETSI Industry Speci i‐
can regularly be hosted in terrestrial networks
cation Group (ISG) Experiential Networked Intelligence
In the case of using HAP, Unmanned Aerial Vehicles (ENI) started around 2017 with the publication of the
(UAV), and nanosatellites as edge network devices, it is White Paper [107]. The main scope of ETSI ISG ENI is
important to choose bands that satisfy the KPI while to design an intelligent architecture for network manage‐
also not interfering with existing terrestrial technologies. ment, taking into account context‐aware policies to adjust
For example, authors in [106] have shown the need for network service provisioning according to users’ needs,
2400 −2483.5 MHz and 2300 −2450 MHz bands for the environmental conditions, and business goals.

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