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What is 5G ? :- 5G (from "5th Generation") is the latest generation of cellular mobile
communications. 5G performance targets high data rate, reduced latency, energy saving, cost
reduction, higher system capacity, and massive device connectivity. All the 5G wireless devices in a
cell communicate by radio waves with a local antenna array and low power automated transceiver
(transmitter and receiver) in the cell, over frequency channels assigned by the transceiver from a
common pool of frequencies, which are reused in geographically separated cells. The local antennas
are connected with the telephone network and the Internet by a high bandwidth optical fiber or
wireless backhaul connection. Like existing cellphones , when a user crosses from one cell to
another, his mobile device is automatically "handed off" seamlessly to the antenna in the new cell.
Performance targets
5G systems in line with IMT-2020 specificatio are expected to provide enhanced device and
network-level capabilities, tightly coupled with intended applications. The following eight
parameters are key capabilities for IMT-2020 5G:
Usage
Capability Description 5G target
scenario
Peak data rate Maximum achievable data rate 20 Gbit/s eMBB
User experienced Achievable data rate across the coverage
1 Gbit/s eMBB
data rate area
Radio network contribution to packet
Latency 1 ms URLLC
travel time
Maximum speed for handoff and QoS
Mobility 500 km/h eMBB/URLLC
requirements
Connection density Total number of devices per unit area 106/km2 MMTC
Data sent/received per unit energy
Energy efficiency Equal to 4G eMBB
consumption (by device or network)
Spectrum Throughput per unit wireless bandwidth
3–4x 4G eMBB
efficiency and per network cell
Area traffic 1000
Total traffic across coverage area eMBB
capacity (Mbit/s)/m2
1G – A term never widely used until 2G was available. This was the first generation
of cell phone technology. Simple phone calls were all it was able to do.
2G – The second generation of cell phone transmission. A few more features were
added to the menu such as simple text messaging.
3G – This generation set the standards for most of the wireless technology we have
come to know and love. Web browsing, email, video downloading, picture sharing
and other Smartphone technology were introduced in the third generation. 3G should
be capable of handling around 2 Megabits per second.
4G – The speed and standards of this technology of wireless needs to be at least 100
Megabits per second and up to 1 Gigabit per second to pass as 4G. It also needs to
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share the network resources to support more simultaneous connections on the cell. As
it develops, 4G could surpass the speed of the average wireless broadband home
Internet connection. Few devices were capable of the full throttle when the
technology was first released. Coverage of true 4G was limited to large metropolitan
areas. Outside of the covered areas, 4G phones regressed to the 3G standards. When
4G first became available, it was simply a little faster than 3G. 4G is not the same as
4G LTE which is very close to meeting the criteria of the standards.
The major wireless networks were not actually lying to anyone when 4G first rolled
out, they simply stretched the truth a bit. A 4G phone had to comply with the
standards but finding the network resources to fulfill the true standard was difficult.
You were buying 4G capable devices before the networks were capable of delivering
true 4G to the device. Your brain knows that 4G is faster than 3G so you pay the price
for the extra speed. Marketing 101. The same will probably be true when 5G hits the
markets.
5G – There are rumors of 5G being tested although the specifications of 5G have not
been formally clarified. We can expect that new technology to be rolled out around
2020 but in this fast-paced world it will probably be much sooner than that. Seems
like a long ways away but time flies and so will 5G at speeds of 1-10Gbps.
Advantages
Speed
5G promises superior speeds in most conditions to the 4G network. Qualcomm presented a
simulation at Mobile World Congress that predicts 490 Mbit/s median speeds for 3.5 GHz
5G Massive MIMO and 1.4 Gbit/s median speed for 28 GHz mmWave . 5G NR speed in sub-
6 GHz bands can be slightly higher than the 4G with a similar amount of spectrum and
antennas,though some 3GPP 5G networks will be slower than some advanced 4G networks,
such as T-Mobile's LTE/LAA network, which achieves 500+ Mbit/s in Manhattan.
The 5G specification allows LAA (License Assisted Access) as well but it has not yet been
demonstrated. Adding LAA to an existing 4G configuration can add hundreds of megabits
per second to the speed, but this is an extension of 4G, not a new part of the 5G standard.
Low communication latency
Network latency is the time it takes to pass a message from sender to receiver.[5G will have
much lower latency than previous cellular networks; below 1 millisecond, compared with 30
- 70 ms for 4G.
New use cases
Features of 5G network, including extreme high bandwidth, ultra low latency, and high
density connections, are expected to enable many new use cases that are impossible to be
done via older network standards.
Technology:-
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1.New radio frequencies:-The air interface defined by 3GPP for 5G is known as New Radio
(NR), and the specification is subdivided into two frequency bands, FR1 (below 6 GHz) and FR2
(mmWave), each with different capabilities.
a.Frequency range 1 (< 6 GHz):-The maximum channel bandwidth defined for FR1 is
100 MHz, due to the scarcity of continuous spectrum in this crowded frequency range. The
band that is most likely to be universally used for 5G in this range is around 3.5 GHz.
b.Frequency range 2 (> 24 GHz):-The minimum channel bandwidth defined for FR2 is is the 50
MHz and the maximum is 400 MHz, with two-channel aggregation supported in 3GPP Release 15.
The maximum Physical layer (PHY) rate potentially supported by this configuration is
approximately 40 Gbit/s. There is no particular band that is likely to be universally used for 5G in
this range, though there are some regional proposals do converge around certain bands.
2.Massive MIMO:-Massive MIMO (multiple input and multiple output) antennas increases
sector throughput and capacity density using large numbers of antennae and Multi-user MIMO
(MU-MIMO). Each antenna is individually-controlled and may embed radio transceiver
components. Nokia claimed a five-fold increase in the capacity increase for a 64-Tx/64-Rx
antenna system. The term "massive MIMO" was coined by Nokia Bell Labs researcher Dr.
Thomas L. Marzetta in 2010, and has been launched in 4G networks, such as Softbank in Japan.
3.Edge computing:-Edge computing is a method of optimizing cloud computing systems by
taking the control of computing applications, data, and services away from some central nodes
(the "core area"). In a 5G network, it would promote faster speeds and low-latency data transfer
on edge devices.
4.small cell:- Small cells are low power, short range wireless transmission systems (base stations)
to cover a small geographical area or indoor / outdoor applications. However, small cells have all the
basic characteristics of a conventional base stations and it is capable of handling high data rate for
individual users. In LTE advanced and 5G deployments, small cells will play a significant role to
efficiently deliver high speed mobile broadband and other low latency applications.
Small cells are further divided into three major categories based the coverage area and
number of users it can support.
Small cell
a.Femtocells:- Femtocells are basically small mobile base stations designed to provide extended
coverage for residential and enterprise applications. Poor signal strength from mobile operator’s base
stations can be solved using Femtocell implementation. Femtocells are primarily introduced to offload
network congestion, extend coverage and increase data capacity to indoor users .
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Key features / Specifications :-
Coverage area 10 meters to 50 meters (indoors)
Power Typically 100 milliwatts
Number of users 8 to 16 users
Backhaul Wired, fiber connection
Indoor (primarily for indoor application, can be used for outdoor
Application
applications)
Cost Low cost
b.Picocells:-
Pico cells are another category of small cells suitable for small enterprises applications for
extended network coverage and data throughput
Key features / Specifications :-
100 meters to 250 meters (indoors)
Coverage area
Power Typically 250 milliwatts
Number of users 32 to 64 users
Backhaul Wired, fiber connection
Application Indoor applications (offices, hospitals, shopping centre and schools)
Cost Low cost
c.Microcells
Micro cells are designed to support slightly large number of users compared to femtocells and
pico cells. Due to high transmission power, it is capable to cover larger cells size and suitable
for application like smart cities, smart metro etc…
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Key features / Specifications :-
Coverage area 500 meters to 2.5 kilometers
Power 2 to 5 watts
Number of users up to 200 simultaneous users
Backhaul Wired, fiber connection and microwave links
Application Outdoor applications
Cost Medium cost
Why 5G requires small cells?:--
5G technology has been designed to focus on three major areas like:
Enhanced mobile broadband: high speed mobile broadband connection up to few gigabytes
per second rate.
Ultra reliable and low latency network: a smart network with less than 1 millisecond
latency and ultra reliability for mission critical applications.
Massive IoT: Internet of Things will connect huge number (millions or billions) of devices
and smart sensors for massive machine communication and several applications in smart
home, healthcare etc…
Conventional mobile network has limitations for further enhancements due to technology,
frequency spectrum (bandwidth) and infrastructure. Each cell has limited number of users and data
capacity. Advanced technologies like massive MIMO and beamforming are used in 5G technology to
increase data rate and spectrum efficiency.
Advantages of small cells:-
Small cells can deliver higher data rate up to few gigabit per second
Less complex solutions, can be easily implemented
Cost effective
Faster deployments
Location requirements are minimum (convenient to deploy indoors and outdoors)
Disadvantages of small cells:-
One of the major disadvantages is coverage limitation due to low power
Number of users under one cell is limited due to resources
Need huge budget for large number of deployments
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Conclusion:-
Since 5G technology is a future framework to support various applications, it has to meet all
necessary specifications. Small cell concept is a perfect solution to deliver enhanced mobile
broadband, low latency and reliable service to users. Higher order modulation techniques,
MIMO technology and millimeter wave spectrum will ensure proper functioning of future
small cell deployments.
5.Radio convergence:-One expected benefit of the transition to 5G is the convergence of
multiple networking functions to achieve cost, power and complexity reductions. LTE has
targeted convergence with Wi-Fi via various efforts, such as License Assisted Access (LAA) and
LTE-WLAN Aggregation(LWA), but the differing capabilities of cellular and Wi-Fi have limited
the scope of convergence. However, significant improvement in cellular performance
specifications in 5G, combined with migration from Distributed Radio Access Network(D-RAN)
to Cloud- or Centralized-RAN (C-RAN) and rollout of cellular small cells can potentially narrow
the gap between Wi-Fi and cellular networks in dense and indoor deployments. Radio
convergence could result in sharing ranging from the aggregation of cellular and Wi-Fi channels
to the use of a single silicon device for multiple radio access technologies.
6.NOMA (non-orthogonal multiple access):-NOMA (non-orthogonal multiple access) is a
proposed multiple-access technique for future cellular systems. In this, same time, frequency,
and spreading-code resources are shared by the multiple users via allocation of power. The
entire bandwidth can be exploited by each user in NOMA for entire communication time due to
which latency has been reduced and users' data rates can be increased. For multiple access, the
power domain has been used by NOMA in which different power levels are used to serve
different users. 3GPP also included NOMA in LTE-A due to its spectral efficiency and is known as
multiuser superposition transmission (MUST) which is two user special case of NOMA.
FULL DUPLEX ( FD)
Full-Duplex (FD) wireless communications for 5G, which enables simultaneous transmission
and reception over the same frequency band. In this way, the spectral efficiency can be
improved significantly compared with half-duplex (HD). However, there exists severe self
interference (SI), signal leakage from the local transmitter to its own receiver. Three different
classes of SI mitigation techniques are presented in this chapter: propagation-domain SI
suppression, analog-domain SI cancelation, and digital-domain SI cancelation. Furthermore,
the system performance of several FD schemes in several different application scenarios is
presented. Theoretically, the spectral efficiency of FD bidirectional and cooperative
communications can be doubled, while for cognitive radio networks, the FD-based protocol
can achieve much better sensing performance than the traditional HD-based cognitive radio
schemes. Today's base stations and cellphones rely on transceivers that must take turns if
transmitting and receiving information over the same frequency, or operate on different
frequencies if a user wishes to transmit and receive information at the same time.
With 5G, a transceiver will be able to transmit and receive data at the same time, on the same
frequency. This technology is known as full duplex and it could double the capacity of
wireless networks at their most fundamental physical layer: Picture two people talking at the
same time but still able to understand one another which means their conversation could take
half as long and their next discussion could start sooner. With full duplex and other 5G
technologies, engineers hope to build the wireless network that future smartphone users, VR
gamers, and autonomous cars will rely on every day. Already, researchers and companies have set
high expectations for 5G by promising ultralow latency and record-breaking data speeds for
consumers. If they can solve the remaining challenges, and figure out how to make all these systems
work together, ultrafast 5G service could reach consumers in the next five years.
