IEEE Network - March / April 2017 - page 82

IEEE Network • March/April 2017n
80
0890-8044/17/$25.00 © 2017 IEEE
A
bstract
The number and variety of mobile multicast
applications are growing at an unprecedented
and unanticipated pace. Mobile network provid-
ers are in front of a dramatic increase in multi-
cast traffic load, and this growth is forecasted to
continue in fifth-generation (5G) networks. The
major challenges come from the fact that mul-
ticast traffic not only targets groups of end-user
devices; it also involves machine-type communi-
cations (MTC) for the Internet of Things (IoT). The
increase in the MTC load, predicted for 5G, calls
into question the effectiveness of the current mul-
timedia broadcast multicast service (MBMS). The
aim of this paper is to provide a survey of 5G
challenges in the view of effective management
of multicast applications, and to identify how
to enhance the mobile network architecture to
enable multicast applications in future 5G sce-
narios. By accounting for the presence of both
human and machine-related traffic, strengths and
weaknesses of the state-of–the-art achievements
in multicasting are critically analyzed to provide
guidelines for future research on 5G networks
and more conscious design choices.
I
ntroduction
The demand for multicast applications over cellular
systems continues to grow rapidly [1]. As a conse-
quence, multicasting will play a key role in emerg-
ing 5G networks, as outlined in white papers (e.g.,
from the NetWorld2020
1
technology platform),
research projects, and standard documents from
the 3rd Generation Partnership Project (3GPP)
[2]. Indeed, multicasting represents a viable and
effective solution to simultaneously convey data
to a group of terminals through point-to-multipoint
(PtM) communication, with positive consequenc-
es on the capacity and the spectrum efficiency of
cellular systems. Both features are crucial for the
deployment of 5G networks [3], as witnessed, for
instance, in the recent METIS
2
and 5GNOW
3
Euro-
pean research projects.
Presently, video communication is considered
as the “killer”
human-oriented multicast application
.
Cisco has stated that the video traffic carried by
mobile networks will reach 15 exabytes by 2019
(13 times larger than 2014). As a matter of fact,
enhanced video services, e.g., ultra high definition
(UHD), 4K and 3D videos, are becoming popular
thanks to the quality of service (QoS) capabilities
of Long Term Evolution (LTE) and beyond systems
[1]. These services, together with the wide range
of entertainment, interactive and real-time applica-
tions filling our daily lives, pave the way for future
5G human-oriented multicasting.
At the same time, network densification is trig-
gered by the wide diffusion of a very large (and
unpredictable) number of low-power devices sup-
porting the deployment of the Internet of Things
(IoT) [3] and exchanging small amounts of data
using machine-type communications (MTC) [3].
The 5G multicast scenario becomes more
complex when considering that small-cells, under-
lying the macro coverage, will be used to enhance
the received signal strength levels associated with
human services, and to increase the capacity in
MTC scenarios, where devices are typically locat-
ed in challenging positions (e.g., indoors, base-
ments) [1, 3]. It becomes evident that the 3GPP
Multimedia Broadcast Multicast Service (MBMS)
[2] needs novel architectural and procedural defi-
nitions to meet the multifaceted constraints of the
expected 5G multicast services.
Although multicasting is attracting an increas-
ing amount of attention from a wide research
community, many challenges still hinder its effec-
tive deployment in 5G networks. By surveying
the relevant literature on this topic, it emerges
that, until now, the primary research efforts have
focused on approaches to boost the data rate
performance (based on short-range links [4, 5],
beamforming [12–14], network coding [10, 11],
etc.) in the view of an improved quality of experi-
ence (QoE) of subscribers. Not enough attention
has been given to the design of architectural and
procedural solutions to meet the new challenges
of multicasting in 5G networks, in which the same
priority has to be given to both human-type and
machine-type group services.
The objective of this paper is to identify and
provide a critical evaluation of the enhancements
required by MBMS to meet the constraints of 5G
human-oriented and machine-oriented multicast
applications. For this purpose, the paper is orga-
nized in such a way to first identify multicast appli-
cation scenarios and related requirements and
then point out enhancements necessary to extend
MBMS in order to satisfy the identified require-
ments. Next, we scan the recent literature on 5G
multicasting in order to highlight the key enabling
technologies already in place to support 5G
group-oriented services and the issues still open.
Lessons learned and future research directions are
finally identified and discussed.
A
pplication
S
cenarios
The mobile market scenario for future 5G mul-
ticast applications is expected to be character-
ized by two types of services [1, 3]: the evolution
of 4G applications tailored for human users; and
the definition of novel machine-based services.
It is thus of primary importance to analyze in
Multicasting over Emerging 5G Networks: Challenges and Perspectives
Giuseppe Araniti, Massimo Condoluci, Pasquale Scopelliti, Antonella Molinaro, and Antonio Iera
Giuseppe Araniti, Pasquale
Scopelliti, Antonella Molinaro,
and Antonio Iera are with the
University Mediterranea of
Reggio Calabria.
Massimo Condoluci is with
King’s College London.
1
2
METIS–Mobile and wireless
communications Enablers for
Twenty-twenty (2020) Infor-
mation Society,
metis2020.com
3
5GNOW–5th Generation
Non-Orthogonal Waveforms
for Asynchronous Signalling,
ACCEPTED FROM OPEN CALL
Digital Object Identifier:
10.1109/MNET.2017.1600067NM
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