5G Network: Architecture and Emerging Technologies

SPECIAL SECTION ON RECENT ADVANCES IN SOFTWARE DEFINED
NETWORKING FOR 5G NETWORKS
Received July 11, 2015, accepted July 22, 2015, date of publication July 28, 2015, date of current version August 7, 2015.
Digital Object Identifier 10.1109/ACCESS.2015.2461602
A Survey of 5G Network: Architecture and
Emerging Technologies
AKHIL GUPTA, (Student Member, IEEE), AND RAKESH KUMAR JHA, (Senior Member, IEEE)
School of Electronics and Communication Engineering, Shri Mata Vaishno Devi University, Katra 182320, India
Corresponding author: A. Gupta ([e-mail])
ABSTRACT In the near future, i.e., beyond 4G, some of the prime objectives or demands that need to
be addressed are increased capacity, improved data rate, decreased latency, and better quality of service.
To meet these demands, drastic improvements need to be made in cellular network architecture. This paper
presents the results of a detailed survey on the fifth generation (5G) cellular network architecture and some
of the key emerging technologies that are helpful in improving the architecture and meeting the demands of
users. In this detailed survey, the prime focus is on the 5G cellular network architecture, massive multiple
input multiple output technology, and device-to-device communication (D2D). Along with this, some of the
emerging technologies that are addressed in this paper include interference management, spectrum sharing
with cognitive radio, ultra-dense networks, multi-radio access technology association, full duplex radios,
millimeter wave solutions for 5G cellular networks, and cloud technologies for 5G radio access networks
and software defined networks. In this paper, a general probable 5G cellular network architecture is proposed,
which shows that D2D, small cell access points, network cloud, and the Internet of Things can be a part of
5G cellular network architecture. A detailed survey is included regarding current research projects being
conducted in different countries by research groups and institutions that are working on 5G technologies.
INDEX TERMS 5G, cloud, D2D, massive MIMO, mm-wave, relay, small-cell.
I. INTRODUCTION
Today and in the recent future, to fulfill the presumptions
and challenges of the near future, the wireless based net-
works of today will have to advance in various ways. Recent
technology constituent like high-speed packet access (HSPA)
and long-term evolution (LTE) will be launched as a
segment of the advancement of current wireless based
technologies. Nevertheless, auxiliary components may also
constitute future new wireless based technologies, which
may adjunct the evolved technologies. Specimen of these
new technology components are different ways of accessing
spectrum and considerably higher frequency ranges, the
instigation of massive antenna configurations, direct device-
to-device communication, and ultra-dense deployments [1].
Since its initiation in the late 1970s, mobile wireless
communication has come across from analog voice calls to
current modern technologies adept of providing high qual-
ity mobile broadband services with end-user data rates of
several megabits per second over wide areas and tens, or
even hundreds, of megabits per second locally. The extensive
improvements in terms of potentiality of mobile communica-
tion networks, along with the initiation of new types of mobile
devices such as smart phones and tablets, have produced an
eruption of new applications which will be used in cases for
mobile connectivity and a resultant exponential growth in
network traffic. This paper presents our view on the future of
wireless communication for 2020 and beyond. In this paper,
we describe the key challenges that will be encountered by
future wireless communication while enabling the networked
society. Along with this, some technology routes that may be
taken to fulfill these challenges [1].
The imagination of our future is a networked society with
unbounded access to information and sharing of data which
is accessible everywhere and every time for everyone and
everything. To realize this imagination, new technology com-
ponents need to be examined for the evolution of existing
wireless based technologies. Present wireless based tech-
nologies, like the 3rd Generation Partnership Project (3GPP)
LTE technology, HSPA and Wi-Fi, will be incorporating new
technology components that will be helping to meet the needs
of the future. Nevertheless, there may be certain scenarios that
cannot be adequately addressed along with the evolution of
ongoing existing technologies. The instigation of completely
new wireless based technologies will complement the current
technologies which are needed for the long term realization
of the networked society [2].
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A. Gupta, R. K. Jha: Survey of 5G Network: Architecture and Emerging Technologies
The remainder of the paper is organized as follows:
In Section II, we present the evolution of wireless
technologies. Section III gives the detailed description of
the proposed general 5G cellular network architecture.
Section IV comprises of the detailed explanation of the
emerging technologies for 5G wireless networks. We con-
clude our paper in Section V. A list of current research
projects based on 5G technologies is shown in the appendix.
II. EVOLUTION OF WIRELESS TECHNOLOGIES
G. Marconi, an Italian inventor, unlocks the path of
recent day wireless communications by communicating the
letter ‘S’ along a distance of 3Km in the form of three dot
Morse code with the help of electromagnetic waves. After
this inception, wireless communications have become an
important part of present day society. Since satellite com-
munication, television and radio transmission has advanced
to pervasive mobile telephone, wireless communications has
transformed the style in which society runs. The evolution
of wireless begins here [2] and is shown in Fig. 1. It shows
the evolving generations of wireless technologies in terms of
data rate, mobility, coverage and spectral efficiency. As the
wireless technologies are growing, the data rate, mobility,
coverage and spectral efficiency increases. It also shows
that the 1G and 2G technologies use circuit switching while
2.5G and 3G uses both circuit and packet switching and
the next generations from 3.5G to now i.e. 5G are using
packet switching. Along with these factors, it also differ-
entiate between licensed spectrum and unlicensed spectrum.
All the evolving generations use the licensed spectrum while
the WiFi, Bluetooth and WiMAX are using the unlicensed
spectrum. An overview about the evolving wireless
technologies is below:
FIGURE 1. Evolution of wireless technologies.
A. 1G
The 1st generation was announced in initial 1980’s.
It has a data rate up to 2.4kbps. Major subscribers were
Advanced Mobile Phone System (AMPS), Nordic Mobile
Telephone (NMT), and Total Access Communication
System (TACS). It has a lot of disadvantages like below
par capacity, reckless handoff, inferior voice associations,
and with no security, since voice calls were stored and played
in radio towers due to which vulnerability of these calls from
unwanted eavesdropping by third party increases [7].
B. 2G
The 2nd generation was introduced in late 1990’s.
Digital technology is used in 2nd generation mobile tele-
phones. Global Systems for Mobile communications (GSM)
was the first 2nd generation system, chiefly used for voice
communication and having a data rate up to 64kbps.
2G mobile handset battery lasts longer because of the radio
signals having low power. It also provides services like Short
Message Service (SMS) and e-mail. Vital eminent technolo-
gies were GSM, Code Division Multiple Access (CDMA),
and IS-95 [3], [7].
C. 2.5G
It generally subscribes a 2nd generation cellular system
merged with General Packet Radio Services (GPRS) and
other amenities doesn’t commonly endow in 2G or 1G
networks. A 2.5G system generally uses 2G system
frameworks, but it applies packet switching along with
circuit switching. It can assist data rate up to 144kbps. The
main 2.5G technologies were GPRS, Enhanced Data Rate
for GSM Evolution (EDGE), and Code Division Multiple
Access (CDMA) 2000 [3], [7].
D. 3G
The 3rd generation was established in late 2000. It imparts
transmission rate up to 2Mbps. Third generation (3G)
systems merge high speed mobile access to services based
on Internet Protocol (IP). Aside from transmission rate,
unconventional improvement was made for maintaining QoS.
Additional amenities like global roaming and improved voice
quality made 3G as a remarkable generation. The major
disadvantage for 3G handsets is that, they require more
power than most 2G models. Along with this 3G network
plans are more expensive than 2G [3], [7]. Since
3G involves the introduction and utilization of Wideband
Code Division Multiple Access (WCDMA), Universal
Mobile Telecommunications Systems (UMTS) and Code
Division Multiple Access (CDMA) 2000 technologies, the
evolving technologies like High Speed Uplink/Downlink
Packet Access (HSUPA/HSDPA) and Evolution-Data
Optimized (EVDO) has made an intermediate wireless
generation between 3G and 4G named as 3.5G with improved
data rate of 5-30 Mbps [3].
E. 3.75G
Long-Term Evolution technology (LTE) and Fixed
Worldwide Interoperability for Microwave Access (WIMAX)
is the future of mobile data services. LTE and Fixed WIMAX
has the potential to supplement the capacity of the network
and provides a substantial number of users the facility to
access a broad range of high speed services like on demand
video, peer to peer file sharing and composite Web services.
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Along with this, a supplementary spectrum is accessible
which accredit operators manage their network very compli-
antly and offers better coverage with improved performance
for less cost [4]–[7].
F. 4G
4G is generally referred as the descendant of the 3G and 2G
standards. 3rd Generation Partnership Project (3GPP)
is presently standardizing Long Term Evolution (LTE)
Advanced as forthcoming 4G standard along with Mobile
Worldwide Interoperability for Microwave Access (WIMAX).
A 4G system improves the prevailing communication
networks by imparting a complete and reliable solution based
on IP. Amenities like voice, data and multimedia will be
imparted to subscribers on every time and everywhere basis
and at quite higher data rates as related to earlier generations.
Applications that are being made to use a 4G network are
Multimedia Messaging Service (MMS), Digital Video
Broadcasting (DVB), and video chat, High Definition TV
content and mobile TV [2], [4]–[6].
G. 5G
With an exponential increase in the demand of the users,
4G will now be easily replaced with 5G with an
advanced access technology named Beam Division Multiple
Access (BDMA) and Non- and quasi-orthogonal or Filter
Bank multi carrier (FBMC) multiple access. The concept
behind BDMA technique is explained by considering the case
of the base station communicating with the mobile stations.
In this communication, an orthogonal beam is allocated to
each mobile station and BDMA technique will divide that
antenna beam according to locations of the mobile stations
for giving multiple accesses to the mobile stations, which
correspondingly increase the capacity of the system [8].
An idea to shift towards 5G is based on current drifts, it is
commonly assumed that 5G cellular networks must address
six challenges that are not effectively addressed by 4G i.e.
higher capacity, higher data rate, lower End to End latency,
massive device connectivity, reduced cost and consistent
Quality of Experience provisioning [22], [23]. These
challenges are concisely shown in Fig. 2 along with
some potential facilitators to address them. An overview
of the challenges, facilitators, and corresponding design
fundamentals for 5G is shown in Fig. 2 [20]. Recently
introduced IEEE 802.11ac, 802.11ad and 802.11af standards
are very helpful and act as a building blocks in the road
towards 5G [9]–[13]. The technical comparison between these
standards is shown in table 1 and the detailed comparison of
wireless generations is shown in table 2.
III. 5G CELLULAR NETWORK ARCHITECTURE
To contemplate 5G network in the market now, it is evident
that the multiple access techniques in the network are
almost at a still and requires sudden improvement. Current
technologies like OFDMA will work at least for next
50 years. Moreover, there is no need to have a change in
the wireless setup which had come about from 1G to 4G.
Alternatively, there could be only the addition of an appli-
cation or amelioration done at the fundamental network to
please user requirements. This will provoke the package
providers to drift for a 5G network as early as 4G is com-
mercially set up [8]. To meet the demands of the user and
to overcome the challenges that has been put forward in the
5G system, a drastic change in the strategy of designing
the 5G wireless cellular architecture is needed. A general
observation of the researchers has shown in [14] that most of
the wireless users stay inside for approximately 80 percent of
time and outside for approximately 20 percent of the time.
In present wireless cellular architecture, for a mobile user
to communicate whether inside or outside, an outside base
station present in the middle of a cell helps in communication.
So for inside users to communicate with the outside base
station, the signals will have to travel through the walls of
the indoors, and this will result in very high penetration loss,
which correspondingly costs with reduced spectral efficiency,
data rate, and energy efficiency of wireless communications.
To overcome this challenge, a new idea or designing tech-
nique that has come in to existence for scheming the
5G cellular architecture is to distinct outside and inside
setups [8]. With this designing technique, the penetration loss
through the walls of the building will be slightly reduced.
This idea will be supported with the help of massive MIMO
technology [15], in which geographically dispersed array
of antenna’s are deployed which have tens or hundreds of
antenna units. Since present MIMO systems are using either
two or four antennas, but the idea of massive MIMO systems
has come up with the idea of utilizing the advantages of large
array antenna elements in terms of huge capacity gains.
To build or construct a large massive MIMO network,
firstly the outside base stations will be fitted with large
antenna arrays and among them some are dispersed around
the hexagonal cell and linked to the base station through
optical fiber cables, aided with massive MIMO technologies.
The mobile users present outside are usually fitted with a
certain number of antenna units but with cooperation a large
virtual antenna array can be constructed, which together with
antenna arrays of base station form virtual massive MIMO
links. Secondly, every building will be installed with large
antenna arrays from outside, to communicate with outdoor
base stations with the help of line of sight components.
The wireless access points inside the building are connected
with the large antenna arrays through cables for communi-
cating with indoor users. This will significantly improves
the energy efficiency, cell average throughput, data rate, and
spectral efficiency of the cellular system but at the expense
of increased infrastructure cost. With the introduction of
such an architecture, the inside users will only have to
connect or communicate with inside wireless access points
while larger antenna arrays remained installed outside the
buildings [8]. For indoor communication, certain technolo-
gies like WiFi, Small cell, ultra wideband, millimeter wave
communications [16], and visible light communications [17]
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FIGURE 2. 5G challenge, facilitators, and design fundamental [20].
are useful for small range communications having large data
rates. But technologies like millimeter wave and visible light
communication are utilizing higher frequencies which are not
conventionally used for cellular communications. But it is
not an efficient idea to use these high frequency waves for
outside and long distance applications because these waves
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TABLE 1. Technical comparison between recent 802.11 standards.
will not infiltrate from dense materials efficiently and can
easily be dispersed by rain droplets, gases, and flora. Though,
millimeter waves and visible light communications technolo-
gies can enhance the transmission data rate for indoor setups
because they have come up with large bandwidth. Along
with the introduction of new spectrum, which is not being
conventionally used for wireless communication, there is one
more method to solve the spectrum shortage problem by
improving the spectrum utilization of current radio spectra
through cognitive radio (CR) networks [18].
Since the 5G cellular architecture is heterogeneous, so it
must include macrocells, microcells, small cells, and relays.
A mobile small cell concept is an integral part of 5G wireless
cellular network and partially comprises of mobile relay and
small cell concepts [19]. It is being introduced to put up
high mobility users, which are inside the automobiles and
high speed trains. Mobile small cells are positioned inside the
moving automobiles to communicate with the users inside
the automobile, while the massive MIMO unit consisting
of large antenna arrays is placed outside the automobile to
communicate with the outside base station. According to
user’s opinion, a mobile small cell is realized as a regular
base station and its allied users are all observed as a single
unit to the base station which proves the above idea of
splitting indoor and outdoor setups. Mobile small cell
users [19] have a high data rate for data rate services with
considerably reduced signaling overhead, as shown in [8].
As the 5G wireless cellular network architecture consists
of only two logical layers: a radio network and a network
cloud. Different types of components performing different
functions are constituting the radio network. The network
function virtualization (NFV) cloud consists of a User plane
entity (UPE) and a Control plane entity (CPE) that per-
form higher layer functionalities related to the User and
Control plane, respectively. Special network functionality as
a service (XaaS) will provide service as per need, resource
pooling is one of the examples. XaaS is the connection
between a radio network and a network cloud [20].
The 5G cellular network architecture is explained
in [8] and [20]. It has equal importance in terms of front
end and backhaul network respectively. In this paper, a
general 5G cellular network architecture has been proposed
as shown in Fig. 3. It describes the interconnectivity
among the different emerging technologies like Massive
MIMO network, Cognitive Radio network, mobile and
static small-cell networks. This proposed architecture also
explains the role of network function virtualization (NFV)
cloud in the 5G cellular network architecture. The concept
of Device to Device (D2D) communication, small cell access
points and Internet of things (IoT) has also been incorporated
in this proposed 5G cellular network architecture. In general,
this proposed 5G cellular network architecture may provide
a good platform for future 5G standardization network.
But there are several issues that need to be addressed in
order to realize the wireless network architecture in partic-
ular, and 5G networks in general. Some of these issues are
summarized in Table. 3 [20].
IV. EMERGING TECHNOLOGIES FOR
5G WIRELESS NETWORKS
It is expected that mobile and wireless traffic volume will
increase a thousand-fold over the next decade which will
be driven by the expected 50 billion connected devices con-
nected to the cloud by 2020 and all need to access and share
data, anywhere and anytime. With a rapid increase in the num-
ber of connected devices, some challenges appear which will
be responded by increasing capacity and by improving energy
efficiency, cost and spectrum utilization as well as providing
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TABLE 2. Evolution of wireless technologies.
better scalability for handling the increasing number of the
connected devices. For the vision of all-communicating world
relative to today’s network, the overall technical aim is to
provide a system idea that supports [21]:
• 1000 times increased data volume per area
• 10 to 100 times increased number of connected devices
• 10 to 100 times increased typical user data rate
• 10 times extended battery life for low power Massive
Machine Communication (MMC) devices
• 5 times reduced End-to-End (E2E) latency
In this paper, we will cover a wide area of technologies
with a lot of technical challenges arises due to a variety
of applications and requirements of the user. To provide a
common connected platform for a variety of applications and
requirements for 5G, we will research the below technology
components [21]:
• Radio-links, includes the development of new transmis-
sion waveforms and new approaches of multiple access
control and radio resource management.
• Multi-node and multi-antenna transmissions, includes
designing of multi-antenna transmission/reception tech-
nologies based on massive antenna configurations and
developing advanced inter-node coordination schemes
and multi-hop technologies.
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