Page 169 - 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

the one in [83] deals with the sharing of the core net- different countries, that over the years have favoured the
work. introduction of MVNOs and roaming mechanisms, we
can observe that the wide service availability at reason-
3.6.2 Infrastructure sharing among different able prices has been considered particularly important
types of networks also with respect to natural market competition.

In the following paragraph we provide some examples With the arrival of 5G, we are observing a renewed inter-
of heterogeneous infrastructure sharing. The work in est in sharing strategies due to the specific virtualization
[78] studies sharing among different Radio Access Tech- technology available and the standardization of network
nologies (RATs), the one in [102] addresses sharing be- slicing. For the first time, the dynamic allocation of net-
tween LTE femtocells and Wi–Fi hotspots whereas the work resources and the service specialization on different
one in [100] investigates 3G offloading over Wi–Fi. Ki- slices, allow serving different groups of users according
bilda et al. [82] deal with sharing among MNOs and to different quality levels. This will likely generate the
OTTs. In [101] the authors propose a RAN architecture interest of new players specialized in vertical applica-
for both infrastructure and spectrum sharing between tion domains, in order to take the role of slice tenants
the MNOs and safety services. Instead the study in and sharing the resources of the network infrastructures
[95] concerns infrastructure sharing between mobile ser- with others. Even extreme scenarios where communi-
vices and smart grid utilities or intelligent transporta- cations resources are traded in real time on automated
tion services. Lin et al. in [93] address backhaul shar- markets are now possible [92], like it already happens in
ing among mobile networks and fixed networks whereas other sectors like energy networks. With this regard, the
Simo-Reigadas et al. in [131] suggest exploiting the com- use of the large toolbox created by research over several
munity infrastructure as backhaul for 3G. years will certainly be an important asset to be used to
shape sharing and trading instruments.
3.6.3 Infrastructure sharing for networks other
than mobile There are however, other important evolution trends of
the technology that will probably influence the sharing
The concept of infrastructure sharing is not exclusive to methods beyond 5G. We want to mention here two of
mobile networks. In fact, it has been applied to fixed them that we believe are particularly relevant:
access networks and problems related to the latter have
been recently addressed in the literature (see e.g., [33] • the extreme distribution of access infrastructure
and [77]). Apart from fixed access networks, infrastruc- with the so-called smart radio environments, and
ture sharing has also been proposed for Wi–Fi networks,
e.g., in [121].
• the full virtualization of connectivity in open and
cloud-based architectures.
3.6.4 Spectrum sharing

As previously stated, the overall literature on the dif-
ferent types of spectrum sharing alone (i.e., not com- As for the smart radio environments, they consider the
bined with infrastructure sharing) is per se very vast. introduction of new equipment at the radio interface of
Unsurprisingly, as spectrum is a scarce resource for the mobile networks, which includes smart repeaters with
MNOs, many papers within this literature resort to dif- large antenna arrays and controllable reflective surfaces.
ferent game theory models (see e.g., [94,135,149,150]). This kind of evolution trend is making clear that in the
future the deployment of multiple physical infrastruc-
3.6.5 MVNO business model tures by different operators will become more and more
difficult and the focus of MNO attention will shift from
The relation among the MNO, its MVNO(s) and the end optimizing their own network to that of efficiently con-
users has been largely addressed through game theory trolling the resources leased from the common infras-
as well (see e.g., [57,87,88,96,134]). tructure.

4. DISCUSSION AND OUTLOOK While the full virtualization of connectivity will be
complete relatively soon, the evolution started years
The large body of literature analyzed in this survey and ago with the separation of the network logic from the
the impact it has had over the years on the standard- pure transmission technology. There are here how-
ization of mobile technologies and the practices adopted ever, important novelties associated with open source
around the world, testify that mobile networks are im- approaches like Open RAN that are becoming popular
portant infrastructures with high costs which can be and that are fostering the transition to cloud-based so-
shared in some scenarios in order to offer better and lutions where the value for service providers will be in
more convenient services to end users. Also, in terms of designing and implementing advanced services based on
regulatory strategies adopted by national authorities in the effective use of transmission resources.

© International Telecommunication Union, 2020 149