Page 118 - ITU Kaleidoscope 2016

2016 ITU Kaleidoscope Academic Conference

density (and/or low-income) population does not justify the OPEX, which instead incur during the management of the
deployment of 5G networks. network. Focusing on the former, solutions aiming at the de-
In this context, the European Union has launched different ployment of cellular networks with low CAPEX costs are of
calls for research proposals in the context of 5G [6]. How- mandatory importance. These costs can be reduced by de-
ever, a specific call of 5G for rural and low-income zones creasing the number of deployed cells per area size. More-
is not included. Rural areas are only indirectly taken into over, authors of [9] clearly show that the exploitation of mas-
account by the proposals on converged architectures. Such sive Multiple Input Multiple Output (MIMO) beamforming
architectures aims at defining a universal network model that is able to reduce the network area power consumption by
can be applied to cities, towns, and small villages. Neverthe- up to 50% compared to standard cellular networks, while
less, the associated costs of these networks are still an open guaranteeing a 10 Mbps cell edge user throughput power.
issue. In this scenario, the lack of connectivity and cover- Alternatively, one radical improvement for the reduction of
age for rural and low-income zones is in contrast with the CAPEX costs is the exploitation of new cellular architec-
Internet purposes. tures. The Loon project launched by Google [10] aims at
providing cellular connectivity by means of balloons natu-
In this paper, we take a new view of 5G networks, by look-
rally moved by the winds of the stratosphere. The same goal
ing at them through the lens of rural and low-income sub-
is also pursued by the Internet project of Facebook [11], with
scribers. In this context, several questions arise: What is
the main difference that the cells are deployed on board of
the current state-of-the-art in the field of 5G research in such
UAVs flying at high altitude and powered by solar panels.
zones? What are the main challenges that need to be faced?
Is it possible to define a holistic 5G architecture explicitly At the same time, solutions aiming at the reduction of OPEX
designed for rural and low-income zones? The goal of this costs are also necessary. One way to reduce these costs is the
paper is to shed light on these issues, and to define future re- exploitation of renewable energy sources. Authors of [12]
search directions. Specifically, we believe that a 5G network investigated the adoption of relay nodes powered by renew-
in rural and low-income zones should be built around the fol- able sources, showing that the radio resources (in terms of
lowing pillars: i) possibility in deploying cells on board of Resource Blocks and transmission power) can be efficiently
small Unmanned Aerial Vehicles (UAVs), ii) exploitation of allocated in order to maximize the user data rates. More-
renewable energy sources, iii) reusability of network compo- over, renewable sources can be also exploited to power macro
nents and functions, iv) deployment of commodity hardware cells. In this context, solar powered cells are being deployed
and v) reduction of CAPital EXpenditures (CAPEX) and OP- to provide connectivity, mainly in some zones of Africa and
erating EXpenditures (OPEX). 1 Asia [13]. Even though the size of the renewable energy
power systems is still an issue [14], the cost of a solar pow-
The rest of the paper is organized as follow. Section 2 re-
ered cell is comparable with a cell connected to the grid,
views the state-of-the-art. The main challenges are reported
in Section 3. Section 4 details our vision. Finally, Section 5 thus much less than exploiting power coming from expen-
sive diesel generators. In addition, the OPEX costs can be
concludes our work.
decreased by reducing the power consumption of cells [15].
This is made possible by the exploitation of different power
2. STATE-OF-THE-ART states (such as full power and low power) which are applied
over time, by taking advantage of the traffic variability. Fi-
We consider the related work in the following domains: wire- nally, another way to reduce the OPEX is the adoption of
less access networks, transport networks, and data centres. virtual network elements, for example by means of Cloud
Radio Access Networks (C-RAN) [16].
2.1. Wireless Access Networks
2.2. Transport Network
Future 5G networks will be characterised by the extensive
deployment of small cells [7]. However, this infrastructure
With the latest 5G requirements of individual user peak
requires huge installation and management costs, due to the
access rates between 1 and 50 Gb/s [5], fibre connections
fact that a large number of sites will be required to be de-
become essential and therefore fibre networks will need to
ployed, coupled also with the need of connecting each site to
reach rural and under-developed areas, where it is important
the rest of the network. Currently, one of the great barriers
to give priority to other characteristics, i.e., low cost/power;
to the development of cellular networks in rural zones is the
resilience to power disruptions, and low maintenance re-
lack of revenues per square mile [8]. However, even an in-
quirements [17].
crease in the competition in the spectrum assignment will not
When looking at today’s fronthaul-backhaul infrastructures,
affect the revenue per square mile experienced by operators.
it can be noticed that radio systems employ a ”remote radio
The costs needed to run a wireless network can be divided
head” strategy in which the Radio Frequency (RF) signal is
into two main branches: CAPEX, which are related to the
sampled and immediately converted to an optical signal for
acquisition and the installation of network equipment, and
transmission to the Base Band Unit (BBU) processing the
1 base band. These units can be placed at the bottom of the
Apart from the connectivity 5G networks may be exploited also to build
the Internet of Things paradigm. tower or centralized in BBU hotels that can be quite far away
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