LTE, LTE-A and 4G

INSIGHT REPORT
LTE, LTE-A AND 4G
the move to the Het Net
EUROPE
MOBILE
SPONSORSREPORT AUTHOR
Zahid Ghadialy,
MD, ExplanoTech
www.explanotech.com

16 | Mobile Europe Insight Report
hird Generation mobile
technology, developed by
3GPP, is deployed throughout
the world in many different flavours and is
officially known as IMT-2000 standard by
the ITU (International Telecommunications
Union), who are responsible for co-
ordinating efforts between different
parties, including the government, private
sector and industries, to achieve a
common set of standards that can
interwork across many different
technologies and countries. Long Term
Evolution (LTE) is the 3GPP standard
Release-8 enhancement involving the
evolution of the air interface and the core
network.
Even though LTE is known as ‘4G’, it is
more of a marketing term rather than
being an actual 4G technology. Some
networks even brand their advanced 3G
networks that have HSPA+ technology as
4G. LTE is a part of the IMT-2000 family
and hence would be considered by ITU as
another flavour of 3G standard. Some
operators brand LTE as 3.9G to signify
that it is one step behind the real 4G.
ITU’s 4G program is officially known as
‘IMT-Advanced’. One of the main
requirements for ‘IMT-Advanced’ is that
the technology should be able to achieve
peak data rates of 100Mbps (Megabits
per second) in fast changing channel
conditions (high mobility scenario) and
1Gbps (Gigabits per second) in slow
changing channel conditions (low
mobility scenarios). LTE-Advanced
(generally referred to as LTE-A) can
achieve these speeds (detailed further)
and can even better them. Hence this is
one of the official 4G technologies as
defined by the ITU.
LTE-A is built on top of LTE and
enhances some of the features to achieve
the desired results. It is officially defined as
part of the Release-10 standards of 3GPP.
Some of the features were considered as
too advanced, and not enough analysis
was done due to tight schedules, and
have been moved to Release-11
(September 2012) and Release-12.
A key thing to remember is that LTE-A
devices are backward compatible so that
they can work seamlessly in an LTE cell. At
the same time, the LTE-A cell should cater
for an LTE device as well as LTE-A device;
both should work without problems.
NEED FOR LTE-A
LTE promises a theoretical maximum
downlink of 300Mbps which is
significantly lower than what is required
for the technology to be IMT-A compliant.
At the same time LTE-A promises a
theoretical maximum of up to 3Gbps.
Even though 3Gbps may be impossible to
achieve, even in lab conditions, it is an
indication that the data rates could be far
higher than can be achieved with LTE.
The higher speeds are necessary for some
of the advanced applications that are
promising to revolutionise our lives. Take
for instance cloud based systems that
could only work in a mobile environment
in an acceptable way if large amounts of
data could be sent and received from
cloud servers.
Sticking with the cloud analogy,
another important requirement is that the
latency should be low — or it may slow
down operations when small bursts of
data need to be sent and received at
regular small intervals. This is achieved by
the small latency periods in LTE-A.
Another issue faced by all mobile
technologies is that cell edge coverage
can be very poor — leading not only to
really slow data rates for users at the cell-
edge but at the same time causing
interference and affecting cell capacity.
This issue is resolved in LTE-A with the
help of Relays and Co-ordinated
Multipoint (CoMP) technologies.
Finally, with spectrum running out in
the lower frequency bands, it has become
even more necessary to utilise higher
frequency bands. The higher the
frequency of radio waves, the lower their
capability to penetrate through physical
T
INSIGHT REPORT
LTE, LTE-A AND 4G
BY ZAHID GHADIALY, MD, EXPLANOTECH
IMT-A LTE (Rel-8) LTE-A (Rel-10)
Bandwidth Scalable, at least 40MHz Scalable, 1.4MHz to 20MHz Scalable, up to 5x20MHz (100MHz max).
Rel-10 supports a max. of 2x20MHz
(40MHz max)
Peak Data rates DL = 1Gbps, UL = 1Gbps DL = 300Mbps, UL = 75Mbps DL = 3Gbps, UL = 1.5Gbps
Rel-10 supports DL=1.2Gbps,
UL = 600Mbps
Latency User plane (UP) 10ms max. 4.9ms 4.9ms
Control plane (CP) 100ms max 50ms 50ms
Peak Spectral Efficiency Downlink (DL) 15 bps/Hz 15 bps/Hz 30 bps/Hz
Uplink (UL) 6.75 bps/Hz 3.75 bps/Hz 15 bps/Hz
Table 1: The need for lTE-A. Increased theoretical maximum peak data rates of 3Gbps, spectral efficiency of 30bps/Hz

Mobile Europe Insight Report | 17
structures like walls. At the same time,
data consumption is increasing indoors
due to the popularity of smartphones and
tablets. To cater for these requirements
operators are in the process of
introducing femtocells and other small
cells. The biggest challenge is to make
them work together without causing
interference with each other, with macro
cells and to the users, regardless of them
being allowed to access these small cells
or not. This requires the need to use
advanced interference avoidance
techniques, which in turn has introduced
‘enhanced Inter Cell Interference
Coordination’ (eICIC).
LTE-A ENABLING TECHNOLOGIES
LTE-A is built on top of LTE, so the
underlying technology is the same. Some
of the characteristics of LTE have been
enhanced in LTE-A while some additional
functions have been introduced. It is
important to differentiate between them.
A network will be considered an LTE-A
network if some of these enhancements
are present. The new functionality can be
considered as a bonus which is good to
have but not necessarily a must have.
CARRIER AGGREGATION
Carrier Aggregation (commonly known
as CA) is one of the main features of ‘LTE-
A’ and is the basis for converting LTE into
an IMT-A capable technology. In the
simplest of forms, CA can be defined as
combining up to five different LTE carriers
into a single carrier.
In an ideal situation each of these
carriers (known as ‘CC’ or ‘component
carriers’) would be 20MHz, thereby
making the total 100MHz. At the same
time is should be pointed out that for a
Release 8/9 LTE device each CC should
still continue to act as an independent CC
as the device is not aware of CA.
Even though in theory CA can
aggregate any bands, there are initially
some restrictions in place. Rel-10
standards define an Intra-band CA
(explained later) for bands 1 (FDD) and
40 (TDD), and Inter-band CA (explained
later) between bands 1 and 5. Rel-11 adds
band 41 (TDD) for Intra-band case and
bands 1 and 19 for Inter-band CA. These
combinations don’t satisfy the likely needs
for every operator and as a result the
following combinations are being worked
on in Rel-11 to satisfy the needs of more
operators (see table below).
Even though the focus is only on two
bands in Rel-10/11, there is a good
INSIGHT REPORT
Ericsson LTE equipment in Stockholm. Huawei has since announced LTE-A trials with Telenor and Tele 2.
Enhancements New functionality
Carrier Aggregation Relays
Enhanced MIMO support HetNets and eICIC
CoMP (Co-ordinated Multipoint)
Other non-LTE-A new features
Bands Operator and/or Region
Band 3, Band 7 Inter-band CA Europe
Band 4, Band 17 Inter-band CA AT&T, USA
Band 4, Band 13 Inter-band CA Verizon, USA
Band 4, Band 12 Inter-band CA USA
Band 5, Band 12 Inter-band CA USA
Band 1, Band 7 Inter-band CA Europe and Asia (mainly China)
Band 3, Band 5 Inter-band CA SK Telecom, South Korea
Band 4, Band 7 Inter-band CA Canada, USA, Latin America, Europe and Asia
Band 11, Band 18 Inter-band CA KDDI, Japan
Band 1, Band 18 Inter-band CA KDDI, Japan
Band 1, Band 19 Inter-band CA NTT Docomo, Japan
Band 1, Band 21 Inter-band CA NTT Docomo, Japan
Band 38 Intra-band CA China and Europe
Table 2: Difference between enhancements, and new functionality in LTE-A
Table 3: Combinations of bands being worked on in Rel-11 for Inter-band Carrier Aggregation

chance that CA with more than two CC
may be specified in the Rel-12 timeframe.
A mobile device declares its capability
by using the ‘UE category’ during the
initial signalling at registration time. For
CA, a new category (category 8) has been
defined that indicates that the mobile
device supports CA. The device further
states its support for different frequency
bands or band combinations as part of its
capability.
There are various types of CA within
LTE, the most basic being Intra-band and
Inter-band. Intra-band is when the CC’s
are within the same band specified in the
3GPP specifications. Since in LTE the
maximum bandwidth could be 20MHz, it
is possible that the band specified is much
larger, say 100MHz. In this case each CC
can be a maximum of 20MHz and
multiple CC’s can be combined from this
band to achieve larger bandwidth and in
turn higher data rates. This scenario
would be known as Intra-band CA.
Intra-band CA could be contiguous or
non-contiguous. Inter-band would always
be non-contiguous. For example Band 1 is
60MHz wide. It may be possible that
some operators have 2x10MHz that may
be non-contiguous. In this case CA would
have to be used to achieve 20MHz. In Rel-
10, for Intra-band CA, only contiguous
spectrum aggregation was supported;
non-contiguous support is present in Rel-
11 version of standards.
Even though the focus right now is
mainly on the Intra-LTE CA, there are
several other forms of CA in evaluation
phase in Rel-12 and beyond. Some of
them are:
T LTE Inter-mode CA: Aggregating CC’s
from FDD (Frequency Division Duplex)
and TDD (Time Division Duplex) bands.
T Inter-RAT CA: Aggregating carriers from
different RAT’s (Radio Access
Technologies) like LTE and HSPA+.
T Licensed and Unlicensed CA:
Aggregating LTE with unlicensed
spectrum technologies like WiFi.
T Intra-LTE Whitespace CA: Aggregating
LTE with whitespace carriers that can be
shared opportunistically between
different operators based on the
requirements. This is a very ambitious
technology with many challenges, chief
among them being the way to
dynamically allocate the spectrum.
The minimum requirement from a Rel-
10 deployment of LTE-A network will
include some form of Intra-LTE CA; either
Intra-band or Inter-band.
ENHANCED MIMO SUPPORT
‘Multiple Input Multiple Output’
(MIMO) is a way of referring to the
multiple antennas present in the
transmitter and/or receiver. A traditional
network that has one transmit antenna
and one receive antenna is referred to as
Single Input Single Output (SISO) system.
MIMO antenna configuration is specified
by M transmit and N receive antenna
elements. When M > N, the system
benefits from ‘transmit diversity’ while
when M < N, the system is enhanced with
‘receive diversity’.
In the simplest of explanations (though
not entirely correct), a 2x2 MIMO, where
there are 2 transmit antennas and 2
receive antennas, can be considered as
doubling the data rate as opposed to a
SISO system. In practice the increase in
data rates due to multiple antenna
elements would depend on a lot of
different conditions, mainly the channel
condition.
MIMO has existed since mid ‘70s. The
amount of processing that is required to
process the MIMO channel in real-time
has been a limiting factor until recently.
With advancements in technology, it is
easier to process received signals much
faster in much noisier environments using
much more complex algorithms. Whereas
once the real-time speed of these
algorithms was the main limiting factor
for the use of MIMO, this is no longer the
case nowadays. The limiting factor now is
a complex combination of the ‘number of
antennas’, ‘real-time processor
requirements’ and ‘power consumption’.
It should be pointed out that the ‘number
of antennas’ is limited by the form factors
of the mobile devices themselves.
The following enhancements have been
done for the Rel-10 of the standards:
REL-10 ENHANCEMENTS
Enhanced DL spatial multiplexing:
The number of antennas has
increased to a maximum of 8x8 in
Rel-10 from 4x4 in Rel-8/9. These
can be combined with
beamforming. In practise though
the most popular configuration
still remains 4x2.
Enhanced UL spatial multiplexing:
The number of antennas has
increased to a maximum of 4x4 in
Rel-10 from 2x2 in Rel-8/9.
Enhanced DL MU-MIMO: Even
though Multiuser-MIMO (MU-
MIMO) was defined in Rel-8, it
had limitations and did not
always produce the desired
results. As a result this feature
was enhanced in Rel-10 to
provide better results.
INSIGHT REPORT
FDD Carrier Aggregation: The R10 UE can
be allocated resources DL and UL on up to
five Component Carriers (CC). The R8/R9
UEs can be allocated resources on any ONE
of the CCs. The CCs can be of different
bandwidths. (Image: 3GPP)

RELAYS
Repeaters have been commonly used
with the mobile technologies. A repeater
receives a signal that is generally weak,
amplifies it and re-transmits it. The
process of amplification also amplifies the
noise that was received by the repeater.
The repeaters are sometimes referred to as
Layer-1 relay or AF (Amplifier and
Forward) type relay.
Relays on the other hand, receive a
signal, decode it and then re-transmit it.
They are also known as DF (Decode and
Forward) type relays. Relays improve
coverage in an area where the signals are
weak but increase the time required for
the signal to reach its final destination.
This means that latency increases with the
Relay node in between. This increase in
latency is still much better than a situation
where re-transmissions increase due to
weak coverage, resulting in low data rates
(indirectly increasing latency) and
reducing the cell capacity.
The main motivations for Relays are
that they would make a mobile device
appear closer to the transmitting antenna,
thereby reducing the amount of power
transmitted and at the same time
resulting in improved throughput.
A Relay appears as a mobile device to
the eNB and as an eNB to a mobile
device. This ensures that legacy Rel-8
devices are unaffected by the Relay node.
The standards have put restrictions that
do not allow the Relay node to move, and
also multi-hop relaying is not supported.
This ensures that latency does not
increase so as to affect the performance
expected from LTE/LTE-A.
HETNETS AND eICIC
A HetNet or Heterogeneous Network is,
in a broad sense, a network that consists
of different types of technologies that co-
exist and are available to be used by the
mobile device in the most convenient and
cost-effective way. In case of LTE it is
generally referred to as the LTE Network,
with different topologies that co-exist to
create a network better than the
individual components of the network.
Occasionally HetNets are confused with
‘Hierarchical Cell Structures’ (HCS) and it is
often assumed that they are different
names for one and the same thing. HCS
includes different types of cells in different
frequency bands. HCS would generally be
deployed with overlapping Macrocells
with other Macrocells/Microcells where
one frequency (generally the lower one)
would be used to improve coverage and
the other frequencies (generally the higher
ones) would be used to improve the
capacity of the network in a geographical
location. HetNets on the other hand can
use the same or different frequencies for
the different types of cells. If different
frequencies are used, there is no need for
having advanced interference
management techniques. If the same
frequencies are used (even partially) then
there is a need to manage the interference
between all the cells that use these same
frequencies. This is the biggest challenge
with the deployment of HetNets.
With the advent of Small Cells
(Femtocells, Metrocells, etc.) and Relays, it
has become necessary that they co-exist
harmoniously among themselves and with
the Macro-cells. There are two main
problems with the non-Macro-cell;
interference to the Macro-cell (reducing
capacity) and interference to other mobile
users who may either be not allowed to
access the services of this non-Macro-cell
— as in case of residential Femtocells that
are configured in ‘closed subscriber
group’ (CSG). Or there may be ‘dead
zones’ in between non-Macro-cells and
Macro-cells, thereby reducing coverage.
In the case of the UMTS family, the
general option used was to put these
small cells on a different frequency so that
they did not cause interference to the
macro cells. There were a few other
techniques that were used to avoid
interference with other small cells.
In case of the LTE family, with the
scalable bandwidths available, it is not an
efficient method to put these small cells
on their own frequency band. The
spectrum available for mobile
technologies is expensive and rare. As a
result in LTE Rel-8, ICIC (Inter-Cell
Interference Co-ordination) was
introduced. ICIC uses the ‘fractional
frequency reuse’ concept like good old
GSM. Using this method, Cell Centre
User’s (CCU’s) are allowed to use all
frequencies but Cell Edge User’s (CEU’s)
are only allowed to use certain
frequencies. This ensures that the high
power used by CEU’s belonging to one
INSIGHT REPORT
The Het Net
(Credit:
4G Americas)

INSIGHT REPORT
cell do not interfere with the CEU’s
belonging to other cells. Small Cells could
use the CEU’s frequencies to keep the
interference to a minimum.
HetNets are expected to become a
commonplace in LTE-deployments, more
for higher capacity and speed rather than
poor coverage issues. In HetNets, small
cells would be distributed throughout the
cell rather than just the cell edge. As a
result the ICIC funtionality was enhanced
(eICIC) to cater for small-cells distributed
throughout the cell as well as the cell
edge users.
In eICIC, the Macro-cell sends an ABS
(Almost Blank Subframe) where no user
traffic is sent. During this time the small
cells can send their data, reducing the
interference between the Small and
Macro cell.
The ICIC feature is designed for a static
environment whereas eICIC is designed to
be dynamic. During peak times the macro
can send few ABS subframes to manage
the traffic in the Macro-cell whereas in the
evening the number of ABS subframes can
increase to cater for heavy indoor traffic.
eICIC is a major tool to reduce
interference between macro and pico
layers, thereby increasing the capacity of
the Macro-cell and at the same time
improving cell-edge throughput and
coverage.
COMP
The main aim of Co-ordinated
MultiPoint (CoMP) Tx/Rx is to increase
the throughput of the mobile device at
the cell edge. The basic idea of CoMP is
similar to soft handover used in UMTS
systems. In CoMP, interference from
neighbour cells at the cell edge is turned
into a useful signal that can be combined
to produce an increased throughput. The
main challenge is to make sure that, asco-
ordination is now be required between
different eNB’s, the processing delay is
kept small and latency is not increased.
Even though Co-ordinated MultiPoint
(CoMP) looks like a straightforward
feature, it has not provided the desired
results in the field. As a result the feature
has been pushed back to Rel-11.
OTHER NON-LTE-A ENHANCEMENTS
Other features, though not directly a
part of LTE-A, are expected to play a big
role in the LTE-A networks. Here is a quick
summary of the important features:
T Self-Organising Networks (SON): With
HetNets, one of the biggest problems is
optimising the transmitters to manage
the power, frequencies, interference, etc.
This is the main intention of the SON.
SON will allow plug and play (PnP)
capability for the deployment of new
network nodes including Macro-cells,
Relays, Small-cells, etc.
T Minimisation of Drive Testing (MDT):
Drive testing is one of the biggest
expenses for a network operator during
the deployment phase. With the
deployment becoming ever more
complicated due to the new topologies,
MDT’s intention is to reduce this
expense saving the operator
considerable sums. MDT is often
referred to as part of SON.
T Enhanced Multimedia Broadcast
Multicast Services (eMBMS): Certain
operators think that eMBMS, which is
seen as a key enabler for Mobile TV
services in the operator spectrum, can
provide additional services and revenue
to them. Even though eMBMS was
standardised in Rel-9, HetNets are seen
as the best opportunity for rolling
eMBMS out.
T Home eNB (HeNB) mobility
enhancements: HeNB is the 3GPP
standard defined term for Small Cells.
Even though the term ‘Home’ is used,
the Small-cell could be a residential,
enterprise, accessible to public or closed
subscriber group type. The intention is
to just differentiate with the Macro-cell.
To provide seamless coverage to the end
user, inbound mobility was specified in
Rel-9 and HeNB to HeNB mobility has
been defined in Rel-10. The latter is a
very important requirement for
enterprise deployments.
T Machine-to-Machine (M2M)
Enhancements: The 3GPP standard
term for M2M devices is Machine Type
Communications (MTC) device. We will
refer to this as M2M for ease of
understanding. M2M is predicted to be
the next big thing. The current number
of mobile connections is estimated to be
10 billion which is expected to reach to
50 billion by 2025. The bulk of these
new connections would be M2M
devices that would be used in our
everyday lives, mostly as sensors for
various applications in smart meters,
consumer products, healthcare and so
forth. LTE/LTE-A is naturally suited for
M2M devices because these devices use
very small amounts of data that can be
sent on the shared channel without
affecting the capacity of the cell in any
way. The enhancements include;
optimisation of the networks to reduce
power consumption, handling of large
number of device groups so that other
important services remain unaffected,
new applications that can be used with
the M2M devices and so forth.
Picture: Ericsson
antenna, Sweden

INSIGHT REPORT
HSPA+ VS. LTE-A
3G and its evolution HSPA/HSPA+ has
been widely deployed throughout the
world. In fact most of the networks have
been now either upgraded to HSPA+ or
are in the process. HSPA+ has its own
evolution path that competes with and
complements LTE. Operators that have
deployed 3G networks would like to
squeeze as much as they can out of it. In
theory this sounds simple but in practice
it may not always be easy.
Many deployments of 3G/HSPA
networks are quite dated, which means
that the hardware is not as flexible as
they are in the newer deployments.
Many technical challenges on SDR and
RF have been solved in the recent years.
As a result a few of these older network
deployments may not be upgradeable
only with software.
They may require new architecture,
hardware and RF (radio frequency)
components. The upgrade costs may be
prohibitive or as high as a new
deployment. These deployments would
reach the end of their life when there is
enough availability and uptake of LTE
devices to justify the re-farming of the
spectrum.
It is still worthwhile comparing the
technologies so that we know the
differences and can see why LTE/LTE-A is
more flexible, efficient and the way
forward.
There are further enhancements defined
in Rel-11 that that will take the HSPA+
data rates even higher. It is unlikely
though that all these enhancements
would be deployed widely. It is accepted
that MIMO works better with OFDMA
(Orthogonal frequency division multiple
access) which is the basis for LTE/LTE-A as
compared to WCDMA (Wideband code
division multiple access) which is the basis
for 3G/HSPA.
The consensus in the industry is that
when the Voice/SMS issues are
completely resolved in LTE/LTE-A and
there are enough mobile devices
available at competitive prices then
the operators would start phasing out
their HSPA/HSPA+ networks and re-
farm the spectrum for LTE-A. With
Carrier Aggregation it would be
comparatively easy to create a wider
HSPA (Rel-10) LTE-A (Rel-10)
Bandwidth Scalable, up to 4 carriers of 5MHz (20MHz total) Scalable, up to 2x20MHz (40MHz total)
Peak DL Data Rates 168Mbps 1.2Gbps
Max. no of Antennas DL 2x2 MIMO 8x8 MIMO
UL SISO 4x4 MIMO
Latency UP 8.67ms 4.9ms
CP 76ms 50ms
Peak Spectral Efficiency DL 8.6 bps/Hz 30 bps/Hz
UL 2.3 bps/Hz 15 bps/Hz
Table 4: Comparison of HSPA Rel-10 and LTE-A Rel-10: “We can see why LTE/LTE-A is more flexible, efficient and the way forward.
Sprint, USA Rel-10 network with CA support in H1, 2013
Clearwire, USA Plans to deploy an LTE Advanced-ready network by June 2013, will be
able to deliver theoretical peak speeds of up to 168 Mbps by 2014
SK Telecom, Korea Successfully demonstrated CoMP at Mobile World Congress (MWC)
2011 and CA at MWC 2012. Plans to launch a Rel-10 network with CA
support in H2, 2013 to achieve data transmission speeds up to
150Mbps . A recent press release showed that SK Telecom have
successfully demonstrated the use of eICIC with Qualcomm and NSN.
T-Mobile, USA Rel-10 network with CA support in AWS bands by 2013
AT&T, USA Plans to deploy LTE-A network in 2013 to eventually use CA to glue
together the 700 MHz spectrum with its existing AWS, 1900 MHz or
850 MHz spectrum holdings. Though it has not been mentioned, the
requirements will only be met by Rel-11 capable network.
NTT Docomo, Japan Conducting field experiments of LTE-A in real radio environments in the
cities of Yokosuka and Sagamihara. NTT DoCoMo has confirmed the
performance of LTE-Advanced technologies using simulators in its R&D
centre, achieving transmission data rates of approximately 1 Gbps on
the downlink and 200 Mbps on the uplink. Plans commercialisation
around 2015.
Mobitel, Slovenia Plans a full deployment of LTE and LTE Advanced using 800 MHz, 1800
MHz and 2.6 GHz bands.
3 Italia, Italy Deploying LTE1800 and from 2013 intends to offer CA allowing
LTE1800 and LTE2600 to be used together.
Tele2 and Telenor, Sweden Announced joint trials of an LTE-Advanced (LTE-A) network.
STATE OF MARKET
Table 5: Operators with announced plans for LTE-A features

bandwidth and as a result achieve
higher data rates.
CHALLENGES AND OUTSTANDING
ISSUES
We have seen above that LTE-A will
help achieve the higher data rates that are
needed for demanding applications like
video-conferencing, pictures/files transfer,
video/audio streaming, etc. It will also
help lay the foundation for new and
innovative applications like cloud-based
services and multi-part video conferencing
applications that require high speeds and
low latency. The benefits are not without
challenges though.
The biggest challenge for LTE/LTE-A
networks is band fragmentation. With the
possibility of having LTE in many different
bands and on top of that different band
combinations for CA, it can be a real
challenge to have devices that will work
for different operators, regardless of the
geography. This could cause two issues;
economies of scale would be difficult to
achieve and roaming interoperability
would be compromised.
The various cells used in CA are mostly
non-overlapping. This means that a
mobile device that is moving will change
different carrier combinations quite often
and this in turn would require signalling
overhead in addition to the radio
frequency (RF) complexities associated
with the device.
The new antennas that are introduced
as part of MIMO require additional
INSIGHT REPORT
Name Features and Timelines
Huawei Unveiled the LTE-A inter-band carrier aggregation (CA) solution at the
Mobile World Congress 2012 in Barcelona and also showcased inter-
band carrier aggregation at 800MHz and 2.6GHz with peak throughput
of over 225Mb/s.
ZTE Demonstrated the base station's interband carrier aggregation
capabilities on two bands - 20MHz channels in 2.6GHz and 1.8GHz and
MIMO to achieve peak rates of up to 270Mbps in the downlink.
Ericsson Demonstrated CA of 3 x 20 MHz channels over the air in a mobile
environment using their multi-mode, multi-standard radio base station,
RBS 6000. It showed speeds more than 10 times faster than the
existing LTE network (June 2011) in Sweden. 8x8 MIMO was used on
the downlink. Expects first stages of LTE-A to be in commercial
operation in 2013.
Nokia-Siemens Networks The Flexi Multiradio 10 Base Station has been used for a demonstration
of super-fast LTE-Advanced data speeds delivering mobile broadband
at 1.4 Gbps on 100 MHz spectrum. Commercially available early 2013.
Also demonstrated speeds of 1.3 Gbps throughput over TD-LTE by
aggregating 60 MHz of spectrum and Multi User MIMO (MU-MIMO)
using the commercial Single RAN Flexi base station hardware.
Table 6: Network Equipment Manufacturers: leading innovations to date.
Aeroflex The TM500 Test Mobile, the de facto industry standard for testing LTE base
stations or eNodeBs, supports all of the carrier aggregation scenarios
specified in 3GPP Release 10, and is also ready for all those currently
proposed for Release 11.
Recently, China Mobile Research Institute (CMRI) and Aeroflex have signed
a memorandum of understanding for a cooperation covering both LTE (Long
Term Evolution) and LTE-A (LTE-Advanced). Under the terms of the
agreement, the companies will collaborate on the testing and verification of
LTE functionality and performance, as well as key LTE-A technologies, such
as carrier aggregation, eICIC (enhanced inter-cell interference coordination),
and UL-MIMO (uplink MIMO), using the Aeroflex TM500 Test Mobile and
EAST500 capacity test system.
Agilent Signal Studio N7624B signal generation software and 89600B VSA LTE-
Advanced software option has specific LTE protocol to set up the
measurement correctly for that technology.These software packages work
Qualcomm The third generation of LTE modem chipsets MDM9225 and MDM9625
support CA, will begin sampling in Q4 2012
Freescale The QorIQ Qonverge 4860 base station-on-chip(SoC) is already
available and supports March 2011 Release 10 LTE Advanced standard.
Table 7: Chipset Manufacturers: support for LTE-A releases.
Picture: Nokia Siemens Networks,
Flexi Base Station

INSIGHT REPORT
reference signals for these new antennas.
These reference signals now increase the
overhead for Rel-10 mobile devices as
they need them to recognise the new
antennas. For the Rel-8/9 devices these
reference signals are interference.
Different technologies in LTE-A have
been discussed but different operators
may choose different deployment
patterns. This may cause instability in the
network for initial periods where the
results may be worse than deploying
without the enhanced features. For
example, Relays and small-cells are
independent of each other yet they
would need to be dealt with in a similar
fashion using SON algorithms. With
small-cells power on/off is not a
guaranteed event, so these algorithms
may have to keep working and make
significant changes dynamically which
may result in stability issues.
REFERENCES/FURTHER READING
Books
1. 4G: LTE/LTE-Advanced for Mobile Broadband by Erik
Dahlman, Stefan Parkvall, Johan Skold
2. LTE Advanced: 3GPP Solution for IMT-Advanced by
Harri Holma, Antti Toskala
3. An Introduction to LTE: LTE, LTE-Advanced, SAE and
4G Mobile Communications by Christopher Cox
Whitepapers
1. Nomor research: Whitepapers on LTE-A -
http://www.nomor.de/home/technology/white-
papers
2. 3GPP: Industry whitepapers -
http://www.3gpp.org/Industry-White-Papers
3. NTT Docomo Technical Journal vol.12 no.2: Special
articles on LTE-Advanced technology -
http://www.nttdocomo.co.jp/english/corporate/tech
nology/rd/technical_journal/bn/vol12_2/index.html
4. LTE-Advanced: An Operator Perspective, Prakash
Bhat et al., IEEE Communications Magazine,
February 2012
5. Overview of enabling technologies for 3GPP LTE-
advanced, Tran et al., EURASIP Journal on Wireless
Communications and Networking 2012, 2012:54.
Websites
1. 3GPP: LTE-Advanced - http://www.3gpp.org/lte-
advanced
2. 4G Americas: LTE-Advanced -
http://www.4gamericas.org/index.cfm?fuseaction=pa
ge&sectionid=352
3. 3G4G: LTE-Advanced (IMT-Advanced) -
http://www.3g4g.co.uk/LteA/
on multiple hardware platforms including MXG Signal
Generators and PXA Signal Analyzers. Key features of these
two products for FDD and TDD, Rel-10 in UL and DL signal
configurations include CA for both contiguous and non-
contiguous component carrier configurations for up to 100
MHz I/Q bandwidth using Agilent's MXG vector signal
generators and up to 140 MHz analysis bandwidth with the
Agilent PXA signal analyser; independent setup parameters
for each component carrier, including any LTE-Advanced
specified bandwidth or modulation type; simultaneous
analysis of up to five component carriers, a feature unique to
the 89600B, and troubleshooting of each component carrier
using a rich selection of measurements, including EVM, CCDF
and more; and enhanced uplink-clustered SC-FDMA and
simultaneous control and data channel (PUCCH and PUSCH)
support.
Also for designing chipsets, the following SystemVue
software W1918 LTE-A library and W1715 MIMO Channel is
available.The library mostly functions at Layer 1, but in
terms of protocol, allows some active HARQ feedback in
closed-loop Throughput simulations.
Anite Currently developing device testing solutions for
development, conformance and interoperability testing
related to LTE-A in collaboration with key industry players.
Road map is aligned to market requirements and notable
features include carrier aggregation, MIMO enhancements
(including higher order antenna configurations, multi-user
MIMO and uplink MIMO) and data-throughput support for
higher UE categories.
Anritsu Demonstrated “full-stack” Carrier Aggregation capability at
CTIA Wireless 2012 with a single MD8430A, based on the
network simulator’s unique availability of two active LTE base
stations and four downlink RF transmitters in a single unit.
When each active base station is configured with two RFs in
a 2x2 MIMO configuration, 150 MB/s downlink throughput is
available from each base station, and 300 MB/s downlink
throughput is available after aggregation. Both intra- and
inter-band aggregation are available with the MD8430A,
using either contiguous or non-contiguous carriers. Recently
MD8430A-085 Carrier Aggregation option was rolled out.
Rohde & Schwarz The R&S®SMU-K85 option allows testing of LTE-Advanced
physical layer features in line with release 10 of the 3GPP
LTE standard. It covers downlink and uplink signal generation
and adds features such as carrier aggregation of up to five
carriers including cross-carrier scheduling as well as
enhanced SC-FDMA uplink. Mandatory prerequisite for the
R&S®SMU-K85 option is the R&S®SMU-K55 LTE option.
Table 8: Test & Measurement Equipment Manufacturers: LTE-A support.

HAT DO YOU THINK ARE
THE CHIEF TECHNICAL
CONSIDERATIONS OF THE
3GPP RELEASES THAT MAKE UP LTE-A?
“LTE-A provides features like multicarrier
aggregation over different frequency
bands, coordinated multi point
transmission, multi carrier aggregation
UMTS+LTE, improved MIMO Mode. The
capability to enable carrier aggregation
for more than 20 MHz is key for higher
data rates. Refarming of existing spectrum
enables us to use additional spectrum for
LTE-A. We may consider further LTE
Frequency planning (fractional frequency
reuse if necessary) to reduce interference.
LTE-A will provide higher data rates over
the entire cell and increase data rate at
the cell edge.
“Multicarrier aggregation over different
frequency bands will enable more flexible
network design. In order to use full LTE-A
capabilities one would have to upgrade
existing Antenna installations from MIMO
4x4 up to 8x8 (Static, authorities, costs,
time).” (Armin Sumesgutner, Director
Network Planning Telekom Austria
Group)
“There are many technical
considerations within LTE-A. Hetnets and
small cells are of primary importance, but
carrier aggregation, CoMP and SU-MIMO
are also important, particularly when you
consider the user equipment updates that
these will require.” (Jens Voigt, Principal
Research Engineer, Actix)
“Achieving LTE-A’s promised peak data
rates of 3 Gbps over a mobile network
poses one of the biggest challenges the
industry has ever had to face. Higher data
rates are achieved through higher
bandwidths, by using carrier aggregation
and evolved antenna configurations. In
order to support highly intensive data
sessions, LTE-A can utilise MIMO transmit
and receive antennas in both base stations
and devices.” (Paul Beaver, Products
Director, Anite)
“The chief considerations to take into
account are Carrier Aggregation, HetNet
technology and User Data Convergence.”
(Avinash Joshi - Director, New Business
Unit (LTE), CTO Office, Tech Mahindra)
“LTE-A is a paradox. LTE was called
‘evolution’ but was a dramatic step.
People are positioning LTE-A as though it
were another big step, but this time it is
an evolution. Or rather, it is a portfolio of
different evolutions: more MIMO, Carrier
aggregation & COMP. Of these CA is the
most immediately useful and valuable.
COMP is very clever and potentially most
important but it will take longer to get
solved and deployed.”(Rupert Baines, VP
Corporate Strategy & Marketing,
Mindspeed)
WILL LTE-A CHANGE ANYTHING,
OPERATIONALLY OR COMMERCIALLY,
FOR MOBILE OPERATORS? IF SO,
WHAT?
“The primary commercial driver for LTE-
A is the continued need to deliver
increased capacity while lowering cost per
bit. Beyond that, LTE-A will not bring
about any fundamental operational or
commercial changes for operators. This is
an evolution, not a revolution.” (Manish
Singh, CTO, Radisys)
“LTE-A capabilities will be used to
further add capacity to manage the ever
increasing data usage in all regions and
operators of the world. The capacity
increase and flexibility in operating
models for managing capacity is the main
area that operators are looking for.” (Per
Kangru, LTE technical expert, JDSU)
“LTE-A requires that operators swap-out
or upgrade previous infrastructure. In
order to control cost, this will initially be
done in limited areas and will result in
islands of LTE-A coverage. Maximisation of
cost-effectiveness means that these LTE-A
sites need to be surgically placed where
the benefit will be greatest. As such, this
constitutes an important aspect of
heterogeneous network (“hetnet”) activity
involving location-aware, subscriber-
centric analysis & decision-making.
Operators will also need to manage
inter-Radio Access Technology (IRAT)
handovers where subscribers transition
from the LTE-A coverage areas to UMTS &
GSM as seamlessly and effectively as
possible.” (Dr. Michael Flanagan, CTO,
Arieso)
“LTE-A is likely to evidence a
generational gap in applications delivery.
Mobile operators face another significant
competitive inflection point. Disruptors,
LTE-A applications and services start-ups,
are gifted with a marvellous commercial
opportunity.” (Robert Marcus, CEO,
QuantumWave Capital)
“Bringing more out of HetNets is one of
the major component of LTE Advanced.
So, mobile operators, in addition to
deploying macro networks, also have to
focus on deploying small cells, and
increase their density, in accordance with
the increase in data traffic.” (Qualcomm)
“With LTE-Advanced, operators will see
significantly reduced operating costs that
they will be able to use to address
broader customer bases and market
needs.” (Andrew Green, VP Marketing,
Mobile Computing, Sierra Wireless)
“The most obvious advantage is the
higher capacity and data rates which can
be provided towards our customers. This
gives us the potential for upselling and
affirm our ‘Best Network’ proposition.”
(Armin Sumesgutner, Telekom Austria
Group)
“On the commercial front, operators
will gain the ability to further extend
products and service offerings into the
business sector, which to date has been
dominated by fixed network centric
applications. From an operational
perspective, migration to LTE-A will
increase network management
complexity, and the deployment of
business applications and media services
will further add to the explosion in data
traffic.” (Paul Beaver, Anite)
W
INSIGHT REPORT
INDUSTRY LTE-A VIEWPOINTS
????????

INSIGHT REPORT
WHAT KEY CHALLENGE, OR
OPPORTUNITY, THAT WILL OCCUR AS
OPERATORS INTRODUCE LTE-A CAN
YOU HELP WITH?
“At Tech Mahindra we provide an array
of services for Carrier Aggregation
including device testing, network
optimisation and managed services.”(Tech
Mahindra)
“Backhaul elasticity is critical to the
viability of HetNets. Operators have to
focus on radically enhancing backhaul
supply to meet increasing and
unpredictable data demand. This means
looking beyond existing technologies that
just meet this demand to those that fully
maximise the significant 4G opportunity,
overcome spectrum limitations, and are
cost efficient.” (Shayan Sanyal, CCO,
Bluwan)
“Through increased automation of
network analysis, management and
optimization, the industry can come closer
to operating in line with the Self-
Organizing Networks (SON) concept and
Actix can provide the unified, vendor-
independent and multi-radio technology
solutions to enable this.” (Actix)
“Customers will demand a high Quality
of Experience for this evolution in wireless
technology. Anite is uniquely placed to
help as we continue to lead the way in LTE
signalling conformance. Anite is responsible
for the verification of over 80% of the LTE
Release-8 protocol tests and offers the
greatest number of unique Global
Certification Forum validated test cases.”
(Anite)
“Where 3G worldwide roaming could be
achieved with 4 or 5 bands, the standards
now describe 40+ specific bands for LTE
use. Carrier Aggregation adds to this the
need to support combinations of bands.
Finding effective RF solutions for the
spectral requirements of each customer is a
huge challenge that we’re working hard to
solve.” (Sierra Wireless)
“The first key challenge will be liberating
LTE-A-capable devices from UMTS & GPRS
networks. The second key challenge is
managing the hetnet interactions of LTE-A
with the more ubiquitous LTE, UMTS &
GPS network.” (Arieso)
“LTE-A upgrades of existing macro sites
will in most cases require some sort of
modifications to the RBS during
deployment including antenna adjustments
etc. JDSU’s tools can ensure that this is
delivered in a smooth and effective way
and ensure that the parts have been fully
qualified in the lab to ensure no negative
operational impact due to issues with
regression on legacy (LTE) functionality.”
(JDSU)
“We have and continue to develop the
advanced interference management
techniques which are part of the HetNet
component of LTE Advanced. We are also
the first to announce chipsets supporting
carrier aggregation.” (Qualcomm)
“Ixia will evolve our testing to address
LTE-A features as they are introduced. Ixia
is currently focused on Carrier Aggregation
support.” (Joe Zeto, Ixia)
“The rollout of LTE-A overlaps with the
critical need for more capacity and for
increased CapEx efficiency. SoCs will (as in
other markets) increase competition and
drive down cost, transforming the wireless
infrastructure market.” (Mindspeed)
WHEN WILL WE SEE COMMERCIALLY
AVAILABLE EQUIPMENT (NETWORK
AND DEVICE) AND COMMERCIAL LTE-A
NETWORKS/ SERVICES?
“This will vary by region as a factor of
local competition and local spectrum
access. US will see LTE-A networks launch
in early 2013 if not in late 2012.” (JDSU)
“ZTE announced LTE-A base stations in
February 2012, and Huawei announced
trials with Tele2 and Telenor in Sweden in
May 2012. Less has been publicly stated
about device readiness for LTE-A, although
test vendor Rhode & Schwarz announced
Rel.10-related gear in August 2012. So, I’d
say the forecast for 2013 is cloudy with a
chance of LTE-A. Clearwire LTE-A rollout
announcements suggest brisker action in
the 2014 timeframe.” (Arieso)
“We expect there to be multiple
product launches at MWC 2013 and that
these products will mature in the latter
part of 2013. We also expect much of the
focus to be in carrier aggregation, relay
and the SON enhancements in the 1st
phase of product launches.” (Radisys)
“The industry is gated behind the R&D
evolution of hardware vendors and
chipset manufacturers, the operators
won't move until their development
roadmaps becomes clear. I don't believe
LTE-A will be mainstream until the middle
of this decade." (QuantumWave Capital)
“Many of the LTE networks deployed
are already LTE-A ready. Both SKT and ATT
have said they will have LTE-A next
year. This is may not be fully commercial,
but the first instances of LTE-A eg with CA
to bond small channels will be deployed
quite quickly.” (Mindspeed)
“It is possible some specific operators
may skip LTE and go straight to LTE-A, or
some specific broadband to home
deployments, this is possible from late
2014.” (Ixia)
We’re likely to hear lots of news about
LTE-Advanced in 2013 and I’d expect to
see significant launches by the middle of
2014.” (Sierra Wireless)
“We expect a commercially launched
LTE-A networks/ services for 2014/15
and commercially available CPEs for
2015/16.” (Telekom Austria)
“Some LTE-A features will likely see
deployment in 2012, but industry
estimates suggest that upgrade migration
will start during 2013 with the availability
of the first production grade handset, and
continue to roll out through 2014/15 and
beyond.” (Anite)
“HetNets are already available today,
with the active deployment of small cells
in high traffic areas. I estimate that this
will be augmented in the next 12
months with the arrival of carrier
aggregation and, finally, the
implementation of CoMP or SU-MIMO
technologies three years from now.”
(Actix)

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