This is the second part of the series of

Technology Digest on the topic “Evolution of

Mobile Communications”.

Issue, May 2018

Telecom Regulatory Authority of India

Evolution of Mobile Communications

In this issue
(4G and 5G) Introduction P1
In first part of this series we introduced initial three generations LTE & LTE Advanced P2
of mobile communication 1G, 2G and 3G. Mankind was getting
OFDMA & SC-FDMA P3
services, opportunities, entertainment, education and much
more at the click of a button or touch of the screen. As a result Small Cells P5
demand expanded and so did the mobile consumers. In the field of Massive MIMO P6
automation, Internet of Things (IoT) also started gaining limelight.
Comparison of different P8
With connectivity and IoT technologies it became possible for a
doctor to perform surgery sitting miles away, through a robot, Mobile Generations
by using internet. Hence the need for faster speed and better Conclusion P8
connectivity aroused. To meet these needs fourth generation of
mobile technology was introduced in 2010. With the entry of new
operator(s) in the mobile services using 4G technology, these services expanded quickly particularly in India.
Now focus is shifted to 5G (Fifth Generation) technologies. Operators in countries like South Korea, Japan and
China are making efforts to start 5G commercial services soon.
This paper is focussed on discussion of 4G and 5G technologies.

Figure 1: Transition from 4G to 5G (Src – Qorvo1)

Fourth Generation
Fourth Generation (4G) of  broadband  cellular network  technology is based on the capabilities defined by
the ITU(International Telecommunication Union) in IMT Advanced (International Mobile Telecommunications
Advanced) which supersede the 3G. It is popularly referred to as MAGIC2 which is the acronym for “Mobile
multimedia, Any-where, Global mobility solutions over, Integrated wireless and Customized services.”According
to the ITU, a 4G network requires a mobile device to be able to exchange data at 100 Mbps for high mobility
communication and 1 Gbps for low mobility communication.
1
Qorvo(2015) is an American semiconductor company that designs, manufactures, and supplies radio-frequency systems and solutions for
applications that drive wireless and broadband communications, as well as foundry services.
2
Noorus Sabah; 4G Technology and its Applications; International Journal of Research in Engineering, Technology and Science, Volume VI,
Special Issue, July 2016

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Network Standards
There are multiple 4G mobile technology standards used by different cellular providers that conform to 4G
requirements, namely, LTE (pre - 4G), LTE-Advanced, WiMAX, and Ultra Mobile Broadband (UMB).
LTE: The UMTS (Universal Mobile Telecommunications Service) cellular technology upgrade termed as Long
Term Evolution (LTE), which is also sometimes called 3.9G or Super 3G,is to accomplish higher speeds along
with lower packet latency. A number of new technologies were introduced by LTE as compared to the previous
cellular systems. For example the OFDMA (Orthogonal Frequency Division Multiple Access) technology and the
SC-FDMA (Single- Carrier FDMA) technology. The UMTS architecture that was used in 3G (Third Generation)
consisted of the Radio Network Controller (RNC) controls the Node Bs and performs resource management and
connects to the Serving GPRS Support Node (SGSN)3. In LTE both the function of NodeB and RNC is performed
by ENodeB – Evolved NodeB.
LTE-Advanced: For LTE Advanced /
IMT Advanced, the number of key
requirements and key features has been
specified4; some of them are as follows:
a. To have maximum downlink speed of
1Gbps
b. To have maximum uplink speed of 500
Mbps
c. To have latency less than or equal to
10ms
d. To have peak spectrum efficiency of
downlink as 30bps/Hz and uplink as Figure 2: Evolution from UMTS technology used in 3G to LTE used in 4G
15bps/Hz
e. Should possess the ability to support scalable bandwidth upto 100MHz
MIMO (Multiple Input Multiple Output) and OFDM are two of the base technologies that will facilitate LTE
Advanced to achieve the high data throughput rates. Along with these, there are a number of other technologies
that will be employed to achieve requirements specified for LTE-advanced. These are:
Carrier Aggregation (CA): Carrier Aggregation utilises multiple channels either in the same bands or in different
bands of the spectrum. This solves the problem of insufficient contiguous spectrum to provide the required
bandwidths for the very high data rates.
Coordinated Multipoint: Poor performance at the cell edges remains one of the key issues with many cellular
systems. The data rates reduce due to interference from adjacent cells. A solution to this problem can be joint
scheduling and transmissions as well as joint processing of the received signals. For LTE-Advanced this scheme
known as coordinated multipoint. In this way, a UE (User Equipment) at the edge of a cell can be served by
two or more eNodeBs (LTE Base Station Component). This will allow improvement in received and transmitted
signals which in turn will increase the throughput at the cell edge.
LTE Relaying:   LTE relaying is a scheme that enables signals to be forwarded by remote stations from the main
base station to improve coverage.
As mentioned earlier there are two access technologies used in Fourth Generation telecom
OFDMA: In Frequency Division Multiplexing, the total bandwidth is divided into several non-overlapping
frequency bands. Each band is used to carry a separate signal. This way a single bandwidth can be utilised to
send a number of signals without any interference amongst them. When modulation of any type - voice, data,
etc. is applied to a carrier, then the sidebands spread out on either side of frequency range.For successful
demodulation of the data, it is necessary for a receiver to receive the whole signal to successfully demodulate
3
SGSN:   Serving GPRS Support Node - the SGSN forms a gateway to the services within the network.
GGSN:   Gateway GPRS Support Node, GGSN, forms the gateway to the outside world.
4
These features are specified by 3GPP (Third Generation Partnership Project); March 2009

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the data. This requires spacing between the transmitted signals so that they can be effectively filtered.
This space is known as the guard band (fig.3). But such is not the case with OFDMA (Orthogonal Frequency
Division Multiple Access). Even though the sidebands from each carrier fold over each other, the signals can
still be received without the expected interference because the carrier signals are orthogonal (statistically
independent) to each other.

Figure 3: Importance of guard bands in FDM

SC-FDMA: Due to the superposition of all the orthogonal signals, OFDMA has a high Peak to Average Power
Ratio (PAPR). Signals with high PAPR require higher energy to be transmitted to long distances. Since base
station acquires a definite land area in each circle which is big enough to provide high energy sources, therefore
OFDMA is suitable for downlinks. But there is a limited battery life of each mobile and it cannot render such
high power signals to the base station for significant time period. As a result, LTE uses a modulation scheme
for uplink communication known as SC-FDMA (Single Carrier FDMA), which is a hybrid format that combines
the low peak to average ratio offered by single-carrier systems with the multipath interference resilient and
flexible subcarrier frequency allocation that OFDMA provides. 
Fifth Generation
The forecast for future 10 years’ traffic demand illustrates an increase in 1000 scales and more than 100 billion
connections of Internet of Things.5 This foists a big challenge for future mobile communication technology
beyond year 2020. The consumers demand a high speed data at low prices. 5G is targeted to resolve these
contradictory demands towards year 2020.  5G was labelled as ‘ultra-fast, ultra-reliable, ultra-high capacity
transmitting at super low latency’ by the National Infrastructure Commission in the report “5G Infrastructure
Requirements in the UK” (2016). Facilities that might be seen with 5G technology include far better levels of
connectivity and coverage. The term World Wide Wireless Web or WWWW is being coined for this.6
Set of 5G requirements

Figure 4: Visions for the Fifth Generation of Mobile Communications (Src - ITU)

5
Guangyi Liu and Dajie Jiang; 5G: Vision and Requirements for Mobile Communication System towards Year 2020;Chinese Journal of Engineering Vol-
ume 2016, Article ID 5974586
6
Swaroop Gandewar et al: 5G:wwww; International journal of advanced Engineering, Management and Science; 2017

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Why do we need 5G?

5G Technology
Millimeter Waves: Telecom Service Providers (TSPs) make use of radio frequency spectrum to send and
receive data. With increasing number of consumers, more data is being consumed. But this data remains
crammed on the same frequency bands. That means less bandwidth for everyone, causing slower service and
more dropped connections. To avoid these problems, TSPs are experimenting with transmission of signals
on a whole new swath of spectrum of 20~50 GHz. This band, acknowledged as the mmWave band, makes
use of higher frequencies than the radio waves that have long been used for mobile phones. The mmWave
band from 20~50 GHz alone accounts for 10 times more available bandwidth than the entire 4G cellular
band.7Many manufacturers are fostering components that can be operated in the range of millimeter waves
and semiconductor technologies that are suitable to operate at frequencies up to 90 GHz, especially in V-band
(57 to 66 GHz) and E-band (71 to 86 GHz) applications. There is one disadvantage to the use of mmWaves, i.e.
due to such high frequencies of mmWaves, they are not able to travel through buildings or obstacles and can
be absorbed by foliage and rain.
Small Cells: Small cells can be placed throughout the cities after every 250 meters or so. They are portable
miniature base stations that require minimal power to operate. Thousands of small cells installed in the city,
due to the short range of mmWave signals, form a dense network called the HetNet (Heterogeneous Network)
that receives signals from other base stations and send them to the users at different locations, like a relay. This
largely prevents signals from being dropped. The term ‘small cell’ encompasses pico cells, micro cells, femtocells
and can comprise of indoor/outdoor systems. Small cells can be as small as the size of a shoe-box. Such small
cells can be bolted to light poles and the sides of buildings, hence do not require separate towers.

Figure 6: Difference between towers of cells

Figure 5: The output power, cell radius sizes and other and the transceiver of the small cells.
features of different base station types, from small cells to
macro cells. (Src – Qorvo)
7 5G Key Enabling Technologies; Mobile tech Insights; Program; Samsung Developers

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Massive MIMO: MIMO is the acronym for Multiple Input Multiple Output. MIMO refers to a wireless
system that uses two or more transmitters and receivers to send and receive more data at once. Presently,
4G base stations possess a dozen ports for antennas to handle all cellular traffic. But 5G base stations can
support about a hundred ports, which mean that a single array can accommodate many more antennas
and hence can send to and receive signals from bountiful users at once. This leads to an increase in
capacity of mobile networks by a factor of 22 or more.8 Below is a list of key technological characteristics
of massive MIMO.
1. Fully digital processing: every antenna bear its own RF (Radio Frequency) and digital baseband chain. The
signals emitted from all the antennas at each base station (due to MIMO) are processed coherently
together. Fully digital processing allows to measure complete channel response on the uplink as well as
quickly responds to such changes in the channel.
2. Computationally inexpensive precoding/decoding : As there are more than one transmitter and receiver
in a MIMO network, there exists one LOS path from every transmitter to every receiver ideally(fig 7a).
However there may be reflection or diffraction from the surrounding atmosphere and the signals could
interfere causing a low SNR (Signal to Noise Ratio) at the receiver. Hence the data streams cannot be
decoded effectively. To avoid this precoding is used on the transmission side with the goal of equalising
the signal reception across multiple receiver antennas.
3. Channel hardening: Due to microscopic changes in environment, the channel gain tends to fluctuate
randomly. This is known as channel fading. The channel is said to have hardened when the fluctuations
in gain do not impact the transmitted data. Channel Hardening effectively removes the effects of
channel fading. Operationally, each terminal-base station link forms a scalar channel whose gain
stabilizes to a deterministic and frequency-independent constant.
4. The reliance on reciprocity of propagation and TDD (Time division Duplex) operation reciprocates the
need for prior or structural knowledge of the downlink propagation channel since the downlink channels
can be estimated from uplink pilots.

Figure 7: Difference between MIMO and Precoded MIMO

5. The array gain offers the link budget improvement and the spatial resolution of the array results in
interference suppression. This facilitates the provision of uniformly good quality of service to all terminals
in a cell.
Beamforming: Beamforming reduces the interference for nearby users by recognising the most efficient data
delivery route from cellular base station to a particular user. Beamforming can help massive MIMO arrays for
more skilled use of the spectrum around them. Massive MIMO faces a challenge to reduce interference while
transmitting information from many antennas at once. At massive MIMO base stations, the best transmission
route is plotted using signal-processing algorithms to send individual data packets in many different directions,
bouncing them off buildings and other objects in a precisely coordinated pattern. Beamforming allows exchange
8
Shaunak Roy; Companies; BBN Times

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 Figure 8: Visual representation of beamforming technology.

of al lot of information between the users and antennas on a massive MIMO arrays by choreographing the
packets’ movements and arrival time. Beamforming and the devices that support beamforming work under
the IEEE 802.11ac specification.


Figure 9: A general 5G cellular network architecture.9

Comparison chart of Generation in Telecommunication10

GENERATION 1G 2G 3G 4G 5G
DEPLOYMENT 1970/1984 1980/1989 1990/2002 2000/2010 2017/2020
DATA
2Kbps 14-64 Kbps 2Mbps 200Mbps 1Gbps
BANDWIDTH
STANDARDS TDMA, CDMA, Single unified Single unified
AMPS WCDMA
GPS, GPRS standard standard

9
Akhil Gupta, Dr.Rakesh Kumar Jha; A Survey of 5G Network: Architecture and Emerging Technologies; IEEE Access 3:1206-1232; Aug 2015

10
Src- Hanamanta NB;5G wireless technology; CITECH; 2015)

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 GENERATION 1G 2G 3G 4G 5G
Unified IP
Unified IP
and seamless
Broadband and seamless
Analog combination of
TECHNOLOGY Digital cellular with CDMA, combination of
cellular broadband, LAN,
IP technology broadband of LAN,
WAN, WLAN and
WAN and WLAN
WWWW
Digital Voice, Integrated Dynamic information
Mobile Dynamic
SMS, Higher high quality Access, Wearable
SERVICES technology information Access,
capacity audio and devices with AI
(voice) Wearable devices
packetized video capabilities

MULTIPLEXING FDMA TDMA, CDMA CDMA CDMA CDMA

Circuit and
SWITCHING Circuit packet All packet All packet
packet

Packet
CORE NETWORK PSTN PSTN Internet Internet
network

Horizontal and Horizontal and

Horizontal Horizontal Horizontal
HANDOFF Vertical Vertical

Conclusion
Rapid growth in data traffic suggests the need of the integration of existing network technologies that permits
dynamic switching amongst the available Radio Access Technologies (RATs) and the efficient utilization
of bandwidth. For radio resource allocation, the concept of super core needs to be implemented that can
coordinate between RATs. The network management modules ought to be more dynamic, cost-effective, and
adaptable, making it ideal for the high-bandwidth and dynamic nature of today’s applications, e.g. Software
Defined Networks (SDNs).
The evolution path of telecommunication from the first generation to the fifth generation provides different
aspects and approaches towards the current state of telecom. The onset of 4G has already revolutionized
the field of telecommunication by bringing the wireless experience to a new level altogether. Further, 5G is
expected to be a milestone development for the success of IoT and M2M communications.
References

[1] TondareS M, Panchal S D, Kushnure D T, Evolutionary steps from 1G to 4.5G, International Journal of
Advanced Research in Computer and Communication Engineering, Vol. 3, Issue 4, April 2014.

[2] Panagiota D. Giotopoulou, The evolution of mobile communications: Movingfrom 1G to 5G,

and from human-to-human to machine-to-machine communications, Nationaland Kapodistrian
Universityof Athens, School of Science, November 2015.

[3] MN Bojouredi, Seidi Haghighat Shoar et al : Low Complexity Statistically Robust Precoder/Detector
Computation for Massive MIMO Systems, School of Electrical and Computer Engineering, University
of Tehran, Tehran, Iran, 2017

[4] Manar Mohaisen, YuPeng Wang, KyungHi Chang:The Graduate School of Information Technology
and Telecommunications, INHA University, 2009

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 [5] LTE OFDM, OFDMASC-FDMA & Modulation. Retrieved from http://www.radio-electronics.com/
info/cellulartelecomms/lte-long-term-evolution/lte-ofdm-ofdma-scfdma.php (Accessed on May
15, 2018).

[6] Understanding 5G: Perspectives on Future Technological Advancements in Mobile, GSMA

Intelligence, December 2014.

[7] 5G Spectrum, Public Policy Position, November 2016, GSM Association.

[8] Emerging Trends in 5G/IMT2020, Geneva Mission Briefing Series, September 2016.

[9] Understanding 5G: Perspectives on Future Technological Advancements in Mobile, GSMA

Intelligence, December 2014.

[10] The Evolution of Mobile technologies: 1G → 2G → 3G → 4G, Qualcomm, June 2014.

Published by: Telecom Regulatory Authority of India

Editorial responsibility: TD Division, TRAI
Contributions, comments and suggestion: sroit@trai.gov.in

Disclaimer:
This document is published as a part of internal academic exercise. This is for academic purpose only. However,
this document does not convey or represent any view of TRAI on any matter whatsoever.

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