High Throughput Satellites
Chapter 15
abdelmehsen.ahmad@liu.edu.lb
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Outline
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Evolution of Satellite Broadband
Multiple Beam Antennas and Frequency Reuse
– Multiple Beam Antenna Array Design
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Total Available Bandwidth
Frequency Reuse Factor
Capacity
– Adjacent Beam SIR
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HTS Ground Systems Infrastructure
– Network Architectures
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STAR Network
MESH Network
– Frequency Band Options
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Satellite HTS and 5G
– Cellular Mobile Technology Development
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First Generation
Second Generation (2G)
Third Generation (3G)
3G Evolution
Fourth Generation (4G)
Fifth Generation (5G)
– Satellite 5G Technologies
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Introduction (1/3)
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Satellite communications technology has evolved through several generations of
development, which have resulted in significant increases in information transfer
capacity and throughput.
First generation satellites were characterized by C-band links operating primarily in
geosynchronous orbit.
– A typical communications satellite payload had 12 to 24 transponders, each with 70 to
120MHz bandwidths, operating with fixed beam full earth coverage antennas.
– Transmissions were primarily analog, with limited flexibility in adjustments to modulation or
processing to enhance communications rates.
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A second generation of satellite communications commenced in the early 1980s
with the implementation of digital communications technology and the extension
to Ku-band operations.
– Steerable beam antennas were introduced, and the first on-board processing transponders
were deployed.
– New satellite services, including broadcast satellite, mobile satellite, tracking and data relay
satellite, and radio navigation satellites were available, and the use of NGSO orbits, primarily
LEO and MEO, were employed.
– Satellite capacity improved significantly, with the use of high power solid-state transmitters,
shaped beam antenna coverage, and steerable spot beams for higher data rate users.
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Introduction (2/3)
• A third generation could be considered with the
introduction of Ka-band FSS in the mid 1990s, which
resulted in an explosion of the number of transponders
and satellite capacity at the global level.
– Many satellite networks operated with both Ku-band
legacy capacity as well as the higher data rate Ka-band
transponders, further expanding satellite capacity and data
handling capabilities.
– The addition of multi-beam technology added frequency
reuse, and full digital link communications offered
extensive enhancements and added capacity options as
well.
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Introduction (3/3)
• Current generation communications satellites have expanded
capacity by efficient use of the allocated frequency spectrum, both
at Ku-band and Ka-band, and have evolved into much larger
capacity payloads with several hundred transponders and extensive
multi-beam and steerable beam antenna arrays.
– The term broadband satellite has become a most common
designation to describe these satellites, particularly those operating in
the Ka-band FSS.
– More recently, a specific subset of communications satellites that
provide a significant increase in capacity, by a factor of 20 or more, has
begun to appear and have been given the classification of highthroughput satellite, or HTS.
• This chapter reviews the industry evolution to the high-throughput
satellite era, and describes the key technology areas and
performance elements, which are expected to define the
communications satellite industry into the next several decades.
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Evolution of Satellite Broadband
• The descriptive term broadband has become common
in current designations of telecommunications
technologies in many areas, including cellular systems,
data management, and satellite communications.
• The term broadband generally refers to a
communications system or technology in which a wide
band of frequencies, that is, a “broad bandwidth,” is
available to transmit information.
• The equivalent opposite term is narrowband, which
refers to a narrowband of frequencies to transmit
information.
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What is broadband?
• The International Telecommunications Union, Telecommunications
Sector, ITU-T, had defined broadband as a transmission capacity
that is faster than the primary service of its Integrated Service
Digital Network (ISDN), which was 1.5 to 2Mbps.
• The United States Federal Communications Commission, FCC, on its
broadband website answers the question “What is broadband”
with:
• “Broadband or high-speed Internet access allows users to access the
Internet and Internet-related services at significantly higher speeds
than those available through “dial-up” services. Broadband speeds
vary significantly depending on the technology and level of service
ordered**. Broadband services for residential consumers typically
provide faster downstream speeds (from the Internet to your
computer) than upstream speeds (from your computer to the
Internet).”
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Examples of broadband, high-capacity
satellites
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Ka-Sat – launched December 2010 (Eutelsat KA-Sat 9A)
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ViaSat-1 – launched October 2011
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built by Space Systems Loral
position 115o West, lifetime 12 years
56 Ka-band transponders
72 spot beams, coverage CONUS, Alaska, Hawaii, and Canada
140 Gbps total throughput capacity
EchoStar 17 – launched July 2012
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built for Eutelsat
location 9o East, lifetime 15 years
82 Ka-band spot beams, 250 km footprint, 10 gateways
70 Gbps total throughput
built by Space Systems Loral
position 107o West, lifetime 15 years
60 Ka-band downlink beams
formerly called Jupiter 1
Intelsat Epic – launched January 2016 (Intelsat 29e)
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built by Boeing Satellite Systems
global coverage
transponders: 14 C-band, 56 Ku-band, 1Ka-band
wide beams, area beams
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Growth in satellite broadband
subscribers
• The growth in broadband and HTS has been accelerated in recent
years as costs for ground terminals and satellite transponders have
been coming down.
• Globally, the number of potential subscribers for satellite services is
expected to rise quickly.
• Figure 15.2 shows the projected growth in satellite broadband
subscribers through 2020 as anticipated by International
Telecommunications Union (ITU) assessments.
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Multiple Beam Antennas and
Frequency Reuse
• The move to the HTS generation of satellite communications
has provided a significant increase in data handling capacity
and throughput for all primary satellite communications
services, FSS, BSS, and MSS.
• The fundamental addition in the architecture of the HTS
compared to earlier generations is the use of multi-beam
antennas to provide coverage to the service area, rather
than the individual wide beams or spot beams of earlier
satellites.
• The use of multiple beams, typically with 100-250 km
diameter footprints, brings two immediate benefits to the
satellite network;
– 1) frequency reuse, and
– 2) higher EIRP on the transmit side and higher G/T on the
receiver side.
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1- Frequency Reuse
• The use of multiple spot beams to cover the service area
allows several beams to reuse the same frequency band,
resulting in a multiple level increase in the capacity of the
system for a given frequency band allocation.
• For example, if the multi-beam network operates within a
frequency band allocation of 100MHz, a frequency reuse
factor of 4 would allow the capacity of the multi-beam
network to function with the equivalent of a 400MHz
allocation.
• Also, with the addition of polarization diversity the capacity
can be doubled for the same frequency band allocation.
• The frequency reuse effect is similar to the increased
capacity available in cellular networks, where terrestrial
cells can reuse the frequency in the same way to increase
user capacity.
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2- Higher EIRP and G/T
• The narrower antenna beams provided by the multi-beam
antenna system results in higher values of transmit and
receive antenna gains on the satellite links, over those
values for wide beam or full earth coverage networks.
• This translates directly in higher effective radiated power
(EIRP) on the transmit side and higher G/T on the receive
side.
• These increased performance links also enable the use of
additional technologies to further increase capacity, such as
higher order bandwidth efficient modulation (BEM), and/or
smaller user ground terminals.
• The better link performance can also possibly allow the
network to operate with a higher level of interference from
other networks or power sources.
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Multiple Beam Antenna Array Design
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The geometry of multi-beam antenna arrays determines many of the performance
parameters of the satellite system, including the frequency reuse factor, and
potential interference between antenna beams operating with the same
frequencies.
We consider now the array of antenna beams on the earth surface, each beam
represented by a hexagon.
– The hexagonal beam shape is conceptual and is a simplified model representing the coverage
area of circular beam subtended by the hexagon.
– The array of hexagons is arranged in clusters, each with the same frequency reuse plan, as
shown by the frequency designations and colors for each beam.
– The number of beams in the cluster, N, contributes to the frequency reuse for the multi-beam
array.
– In addition, if polarization diversity is implemented, an additional option for reuse is
introduced.
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Total Available Bandwidth
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Frequency Reuse Factor
For the example (2) with a cluster size N = 4, and each beam operating with dual
polarization and a 100MHz allocated bandwidth, a satellite array with 20 total beams
FR = 2(20)/4 =10.
If polarization diversity is not employed, FR = (20)/4 =5.
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Capacity
• The capacity of the multi-beam satellite network, usually expressed
in bps, will be dependent on several transmission factors, including
the modulation type employed, coding, mitigation processing, and
other network performance characteristics.
• If the spectral efficiency ηs, of the satellite transmission is specified,
then the capacity, C, of the multiple beam satellite network can be
determined from,
The capacity increases with the number of beams, NB, but decreases as
N is increased, which is a major trade involved in the design of
multiple-beam HTS satellite systems
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Adjacent Beam SIR
• One important consideration in the design of the multibeam array is the performance trade-off between the
beam parameters such as frequency reuse factor, beam
footprint size (and its associated beamwidth), power and
antenna gain for the transmit terminal, and receiver
performance.
• A major element in the design trade is the potential for
interference on downlink transmissions from adjacent
beams with the same frequency plan.
– As the reuse factor is increased, the physical separation
between co-channel (same color) beams gets larger, reducing
the potential for interference.
– However, an increase in N results in a reduced bandwidth
available for each beam, as we saw before.
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Determination of nearest co-channel
beams
DN the distance between the
two nearest co-channel beams.
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Signal to Interference Ratio
The Adjacent Beam Signal to Interference Ratio, SIR, for the network, defined as,
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HTS Ground Systems Infrastructure
• The network ground terminals associated with HTS networks differ
from traditional satellite networks in several ways:
– 1) high capacity beams of several hundred MHz each in bandwidth,
with associated higher data rates,
– 2) user terminals operating with significantly higher data rates over
wider bandwidths,
– 3) feeder link terminals supporting multiple spot beams, with
continuous Gbps capacity,
– and 4) the deployment of fade mitigation techniques (as discussed in
Chapter 8), for high rain fade avoidance, particularly for Ka-band HTS
networks.
• Each of these factors impact the design and performance for all of
the ground elements of the network, with the user terminals and
the feeder link terminals (also referred to as gateways) throughout
the multi-beam operations area.
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Network Architectures
• HTS networks operate with the two same basic
topologies of satellite networks that do not
employ multi-beam antennas in large numbers.
• If the HTS network employs gateways, their
locations now must be integrated into the multibeam structure in order to serve several
collocated beams with possible Gbps total
capacity requirements.
• The two topologies are the STAR network and
the MESH network.
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STAR Network
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The STAR network provides two-way (duplex) data communications between user
terminals through a gateway or hub terminal.
The transmissions between any two user terminals must go through a gateway;
there are no direct links between user terminals.
– This allows the user terminals to be smaller (in antenna size and RF power) since link closure is
established with the much larger antenna and higher RF power gateway terminal.
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The link from the gateway is the forward link, whereas the link to the gateway is
referred to as the return link.
– The link to and from the gateway is the feeder link of the network.
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Since the STAR configuration does not provide a direct transmission link from user
to user, the transmissions (in either direction) require a double hop through the
satellite to complete.
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MESH Network
• The second basic satellite network is the MESH network, where any user
terminal can communicate to another user terminal directly through the
satellite.
– There is no gateway terminal needed for the user to user transmission.
• The MESH configuration provides a single hop for user terminal to user
terminal transmissions.
– On-board processing allows any user in one beam to talk to any user in the
same beam or another beam in the array.
– The user terminals in the MESH network require more capabilities than the
STAR user terminals, such as larger antennas, better eirp, and better G/T, since
they do not have the benefit of a large gateway on one end of the link to
enhance link performance.
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Services and applications
• Typical HTS applications with either topology include many services
for a large market of users.
• User terminals can be traditional size VSAT terminals or smaller USAT
(ultra-small aperture terminal) terminals operating with a 25 to 100+
multiple beam network, each with 100 km radius footprints.
• Services and applications that benefit from STAR connectivity include:
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broadband Internet access
webcasting and streaming
direct-to-home television service
emergency communications services
• Those that tend to favor MESH networks include:
– secure intranet and VPN (virtual private network) data exchange
– M-to-M (machine to machine) supervisory control and data transfer
– Distance learning and distance healthcare networks
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Satellite HTS and 5G
• Terrestrial cellular mobile networks, which have evolved through several
generations of technology development, have not generally contained a
satellite communications component to any great extent.
• The cellular structure and emphasis on small, localized cells providing
voice and moderate data rate point-to-point communications, has not
required satellite communications to provide user-to-user connection.
• The one exception is the use of satellite for backhaul services for long
distance and intercontinental connections.
• This lack of satellite links in terrestrial cellular service delivery is changing
quickly, however, as fourth generation (4G) mobile systems move into fifth
generation (5G) technology expansion.
• Satellite services, particularly HTS systems, will play a major role in 5G
networks.
• Before we discuss the anticipated role of satellite technology in 5G
cellular, a brief overview of the evolution of cellular mobile technologies
through previous generations will provide a useful perspective on how
satellite networks will fit into the 5G telecommunications infrastructure.
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Cellular Mobile Technology
Development (1/6)
• First Generation (1G)
– The first generation of terrestrial cellular networks,
which began deploying in the early 1980s, were based
on analog modulation and FDMA technology.
– The modulation was usually FM, and network control
resided in a centralized control location, referred to as
the MTSO (Mobile Telephone Switching Office).
– Handoff, the process of transferring a mobile user
terminal to the next appropriate neighboring
terrestrial cell, was also controlled by the MTSO.
– The first generation cellular standard in the United
States was AMPS (Advanced Mobile Phone Services).
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Cellular Mobile Technology
Development (2/6)
• Second Generation (2G)
– Second generation cellular systems, which began to appear in the early 1990s,
introduced digital technologies and advanced call processing capabilities.
– Digital voice coding and digital modulation were employed.
– TDMA and CDMA access control first appeared with 2G systems.
– Network control structure was more distributed, with functions such as
handoff decisions moved to the individual user handsets, rather than to a
centralized control.
– Some of the more popular 2G standards to be deployed were:
• GSM (Global System for Mobile)
• TIA (Telecommunications Industry Association) standards
– IS-54 TDMA digital standard
– IS-95 CDMA digital standard
• PACS (Personal Access Communications System)
• 2G standards have been replaced and are no longer in service, with the
exception of GSM, which, in a significantly modified and improved format,
is still used throughout the world.
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Cellular Mobile Technology
Development (3/6)
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Third Generation (3G)
– The next major technology change in cellular systems evolution was the family of standards
based on the International Telecommunications Union (ITU) International Mobile
Telecommunications Program, IMT-2000.
– These standards, which began to be deployed in 2000, are referred to now as third generation
(3G) cellular.
– 3G evolved from 2G systems, which were primarily supporting voice and low rate data, to
include;
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Wireless wide-area network(WLSN) voice telephony
Video and broadband wireless data
IMT-2000 had as its primary goal to provide a single set of standards that can meet
a wide range of wireless applications and provide universal access.
The first commercial 3G network, NTT DoCoMo, was launched in October 2001 in
Japan.
The first 3G network in the United States was initiated by Verizon in October 2003.
3G standards are maintained by the IMT-2000 3rd Generation Partnership Project
(3GPP).
The 3GPP is based on the IMT-2000 standard called UMTS (Universal Mobile
Telecommunications System) or a slightly improved standard called WCDMA
(Wideband CDMA).
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Cellular Mobile Technology
Development (4/6)
• 3G Evolution
– The 3G era moved quickly into an “evolution” period, which saw
three competing technologies vying for the next generation of
cellular. In addition to the UMTS/WCDMA, two other technology
standards appeared: HSPA (High-Speed Packed Access) and LTE
(Long Term Evolution).
– LTE, which appears to be the technology of choice for 3G
evolution, was initiated at a 3GPP workshop in November 2004.
– LTE utilizes OFDMA (Orthogonal Frequency D ivision Multiple
Access) and SC-FDMA (Single Channel-Frequency Division
Multiple Access) instead of CDMA.
– It is an all IP (Internet Protocol) network, and advertises reduced
cost per bit capability over the other two 3G evolution
alternatives.
– 3G-LTE has evolved into the major “post 3G” global standard
and is the dominant advanced cellular technology in general
use.
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Cellular Mobile Technology
Development (5/6)
• Fourth Generation (4G)
– Fourth Generation is the term used to describe the next complete evolution in
cellular wireless broadband communications.
– 4G would be a full evolutional system, that is, it would replace 3G or 3G/LTE
handsets, components, and networks, as 2G did with 1G and 3G with 2G.
– 4G specifications are based on the IMT-Advanced requirements initiated by
the ITU in 2008. An IMT-Advanced cellular system must fulfill the following:
• An all-IP packet switched network
• Peak data rates of up to 100Mbps for high mobility such as mobile access and up to 1
Gbps for low mobility such as nomadic/local wireless access
• Dynamically share and utilize the network resources to support more users per cell
• Scalable channel bandwidth, between 5 and 20MHz, optionally up to 40MHz
• Peak link spectral efficiency of 15 bits/s/Hz downlink, and 6.75 bits/s/Hz uplink
• Smooth handovers across heterogeneous networks
• Ability to offer high quality of service for next generation multimedia support
• Two approaches in active development to meet the IMT-Advanced
requirements are;
– 1) LTE Advanced, developed by the 3GPP, and,
– 2) IEEE 802.16m, a standard developed by the Institute of Electrical and
Electronic Engineers
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Cellular Mobile Technology
Development (6/6)
• Fifth Generation (5G)
– If we note that past new mobile generation standards have
appeared approximately every 10 years beginning with first
generation (1981), 2G [GSM] (1992), 3G [IMT-2000] (2001) and
4G [IMT-Advanced] (2010–2011), the first 5G deployments
would be expected around 2020.
– Consistent with this timeframe, the ITU-R is developing its
roadmap for 5G development through its IMT-2020
(International Mobile Telecommunications-2020) initiative .
– The timeline shows the work plan process, beginning with early
planning before WRC-15 and moving to WRC-19.
– The numbered items on the top of the timeline indicate the
meeting numbers for Working Party 5D, commencing with #18
in 2014 and extending to #36 in 2020. Several reports have been
published which discuss technology, feasibility and vision related
to IMT-2020 5G development .
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Satellite 5G Technologies
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The move to the 5G environment will see a merging of several technologies, which
involve not only the traditional 2G/3G/4G terrestrial cellular services of today, but
will see an expansion of broadband high data rate services and will include
satellite and possibly high altitude platforms as well as expanded terrestrial
components.
Some of the technologies driving 5G era implementation include:
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Software Defined Radio Access Technologies (RATs)
Cognitive radios
High Altitude stratospheric platform stations (HAPS)
Machine to machine (M2M) communications
Internet of Things (IoT)
Increased screen resolution (i.e., 4K, UHD) and video downloading
Cloud Computing
The major impact of these technologies is a rapid projected growth in IMT traffic in
the IMT-2020 era.
Three user trends that are leading the move towards rapid traffic growth are:
– 1) increased video usage,
– 2) “smart” device proliferation,
– 3) rapid acceleration of applications and downloading
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Satellite 5G Technologies
• HTS can be expected to deliver very high data rate services in point-topoint, broadcast, multicast, and delivery to small outdoor radio access
points.
• Satellite-based networks will help to interconnect wireless access
networks for in-home and in-building distribution, including in-building
mobile users.
• Current HTS delivery of scheduled (linear) video and on-demand (nonlinear) TV will expand as demand for downloading and IP services
increase.
• The 5G “Ecosystem” will contain a vast array of services and satellite
delivery networks will play a major part in its implementation.
• 5G will require large blocks of contiguous spectrum, not available below
31 GHz.
• Satellite delivery will be essential to allow the development of the
innovative planned broadband services, and Ka-band (and higher) HTS
systems will be at the center of these networks.
• By the year 2025 one estimate envisions that there will be over 100 HTS
GSO and NSO systems in orbit delivering Terabits of global connectivity.
• Satellite HTS spectrum will be primarily at Ka-band, however, FSS
allocations in Q-band(40/30) and V-band (50/40) are already under
intense study and evaluation.
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5G services and activities
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The 5G environment is a combination of new technology working with existing
technology, in activities such as (see figure 15.5):
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Security and Surveillance
Telemetry and data backhaul
Fixed and mobile asset tracking
E Health Traffic Priority
Flight Tracking
Connected House: Broadband Services, Hybrid Multiply/Local Storage
Smart Grids
Smart Mobility
Fleet Management
Remote Control of road Signs
Connected Car
Utility Management
M2M SCADA (Supervisory Control And Data Acquisition) applications
Smart Parking
Smart Wearables
Staff Location Tracking
Merchant Shipping, Crew Welfare, Passenger Connectivity
Civil Security: Interoperable first response across borders
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