The document discusses the APT700 band plan, which divides 700 MHz spectrum into blocks that can support both FDD and TDD LTE networks. It notes that adoption of the APT700 plan by countries in Asia-Pacific and Latin America regions represents a major opportunity for global spectrum harmonization. Harmonization allows for economies of scale, lower device costs, improved roaming between countries, and additional network capacity. The plan is gaining support internationally and has the potential to serve over 4 billion people globally with LTE networks.
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1. APT700 – AN EFFECTIVE
BAND FOR GLOBAL
HARMONIZATION
STRATEGIC WHITE PAPER
Adoption of the 700 MHz Asia-Pacific Telecommunity band plan (APT700)
by a growing number of countries across the APAC and Latin America regions
represents a major opportunity for global spectrum harmonization of LTE
systems with the potential to serve over 4 billion people globally. This step paves
the way for economies of scale for devices and network infrastructure, fosters
improved roaming and provides additional capacity to support new mobile
broadband services.
This white paper offers background on the state of APT700 around the world,
including the economic and technical benefits of the band plan. It also addresses
technical considerations for implementing networks within this plan and provides
an overview of the Alcatel-Lucent APT700 solution.
2. TABLE OF CONTENTS
1. Introduction / 1
2. APT700 around the world / 2
2.1 Creation of the digital dividend (ITU Regions 1, 2 and 3) / 2
2.2 Significance of APT700 / 2
2.3 Global harmonization / 3
2.4 Device availability / 5
3. Addressing spectrum efficiency / 5
3.1 The US digital dividend band plan / 5
3.2 The APT digital dividend band plan / 7
3.3 ITU Digital dividend band plans / 8
4. Technical considerations / 9
4.1 Interference / 9
4.2 Global roaming / 15
4.3 Dual duplexers in terminal equipment / 16
4.4 Antenna size / 16
5. Alcatel-Lucent APT700 solution / 17
5.1 Solution component overview / 17
5.2 Solution benefits / 17
6. Conclusion / 18
7. Acronyms / 18
3. APT700 – An Effective Band for Global Harmonization
ALCATEL-LUCENT STRATEGIC WHITE PAPER
1
1. INTRODUCTION
Mobile network operators face the challenge of meeting rising mobile broadband
demand. The availability of new devices, applications and faster access technologies is
leading to increases in subscriber usage. Using a conservative model, a Bell Labs analysis
of operator networks worldwide forecast a tenfold increase in monthly per-subscriber
usage — from roughly 0.5 GB per user each month in 2013 to 5.0 GB per user each
month in 2017.
Operators have a number of ways to address this growth. Primarily, they plan to handle
it through a mix of new spectrum, via increases in spectral efficiency delivered by newer
technologies like LTE and through further spatial densification of the network,
for example, by using small cells.
Recognizing the importance of meeting broadband demand and its impact on stimulating
economic growth, governments have been freeing so called “digital dividend” spectrum
operating at sub-1 GHz. The excellent propagation characteristics of this spectrum enable
better coverage and in-building penetration. However, its availability varies across
countries, and different band plans have been adopted, as a result.
It is widely recognized that both developed and developing countries could gain from
global harmonization. It would allow economies of scale and enable more cost-effective
devices to become available, as vendors are assured of high volumes. It would also
enable better roaming, because the same band plan could be used across countries.
As a result, many countries have either opted for the APT700 band plan already, or they
are now considering such a plan. The APT700 band plan has been designed to enable
the most efficient use of available spectrum. It divides the band into contiguous blocks of
frequencies. For Frequency Division Duplex (FDD), the plan creates two 45 MHz blocks
of spectrum, one for downlink and one for uplink. For Time Division Duplex (TDD),
a single 100 MHz block of continuous spectrum is used.
This paper examines the state of APT700 around the world, addresses technical
considerations for implementing networks within this band plan and includes an
overview of the Alcatel-Lucent APT700 solution.
4. APT700 – An Effective Band for Global Harmonization
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2
2. APT700 AROUND THE WORLD
A growing number of countries across the Asia Pacific and China (APAC) and Latin
America regions are adopting the APT700 band plan. This trend represents a major
opportunity for global spectrum harmonization of LTE systems. Figure 1 provides a
projection of the global population covered by digital dividend bands with the APT700
band plan showing the highest level of growth in the coming years.
0
1000
Millioninhabitants
2000
3000
4000
5000
6000
Asia
Latin America
700 US 800/700 EU 700 APT
Europe
Africa
US
Canada
7000
2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020
2.1 Creation of the digital dividend (ITU Regions 1, 2 and 3)
Digital dividend is the term commonly applied to spectrum that has been made available
for alternative uses by the transition from analog to digital television broadcasting. The
introduction of digital television (DTV) has reduced the amount of spectrum required
to provide broadcast television services. This spectrum is in the UHF band and is
highly attractive for cellular operations because of its propagation characteristics. The
digital dividend varies by region, because the spectrum used for analog television was
not identical. In ITU Regions 2 and 3 (the Americas and Asia-Pacific), the first digital
dividend is in the frequency band 698 MHz to 806 MHz, sometimes referred to as the
700 MHz band. (The digital dividend in ITU Region 1 [EMEA] is 790 MHz to 862 MHz
and is not considered in this paper).
2.2 Significance of APT700
Because of its excellent propagation characteristics, the low-frequency sub-1 GHz
spectrum is ideal for providing both outdoor and deep indoor coverage, in both rural
and urban environments:
In rural areas: These bands are effective for helping to ensure mobile system coverage
in a cost effective manner. By using this spectrum fewer sites are needed leading to
reductions in the cost of network roll-out and the cost of providing services.
In urban environment: The lower-frequency bands tend to refract better around
corners and can pass more easily through walls. Therefore, low frequencies provide
improved indoor coverage.
Figure 1. Digital dividend band plan coverage of the world population
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The sub-1 GHz spectrum is ideal for economically deploying mobile coverage relatively
quickly in wide areas, as well as for in-building use. According to a GSMA study1
the
low-frequency bands enable mobile operators to build low-cost networks capable of
handling the explosion of data consumption. Deploying a network that uses higher-
frequency capacity bands requires more base stations to cover the same area. Rolling
out a 700 MHz–based network can save up to 30 percent of the cost of rolling out a
2100 MHz–based network, and this translates into greater access and a more affordable
service for customers.
Figure 2. Relative number of sites and CAPEX for coverage
0
CAPEX
3500 MHz
28
5
10
15
20
25
30
35
2600 MHz
9
2100 MHz
5
1800 MHz
4
900 MHz
1.1
800 MHz
1.0
700 MHz
1.0
1.0
Site need
1.0 1.2 4.6 5.6 10.8 35.6
CAPEX
2.3 Global harmonization
Governments have a major role to play in the way mobile Internet unfolds. As economic
activities become more dependent on the Internet, its availability and reliability are now
topics ranking high on the countries’ political agendas. Governments around the world
are realizing the added value that broadband access and information and communication
technology (ICT) can potentially bring to any public service, in areas as different as
education, health, security, entrepreneurship and social programs. As a result, they are
interested in the radio spectrum as a means for effectively creating a new convergence
of governmental and commercial traffic over IP.
The APT700 plan also known also as the “2 x 45 MHz option,” offers the best chance to
answer the governments’ goals while delivering the benefits of regional harmonization.
The band is likely to be allocated for mobile broadband (MBB) services in both Asia Pacific
and Latin America, at different times during 2014 through 2017, which gives it the potential
to become the most-used band for LTE worldwide, covering over 4 billion people.
The Asia Pacific Telecommunity Wireless Group completed planning for the APT700 plan
in late 2011. This plan was the result of careful study, debate and deliberation, which took
into account existing deployed systems, band-edge sharing issues, filter capabilities, the
LTE (IMT Advanced) standard and current 3GPP work toward expanding the 850 MHz
band. It therefore represents one of the most carefully crafted plans that takes into account
the complex needs of a wide range of countries within and beyond Region 3.
The APT700 plan protects adjacent television broadcasting services by using a significant
guard band and defined emission limits, which are reflected in the newly released 3GPP
Band 28 Frequency Division Duplex standard.
1 http://www.gsma.com/spectrum/wp-content/uploads/2013/07/GSMA-Policy-Position-on-the-Digital-Dividend.pdf
6. APT700 – An Effective Band for Global Harmonization
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Beyond the technical deliberations, one of the most important factors in developing this
plan was economies of scale for handset manufacturers. The administrations, vendors
and carriers involved were well aware of the benefits to developing nations of Internet
access using affordable handsets and tablets. It is perhaps this reason, more than others,
that has encouraged many countries beyond ITU-R Region 3 to recently adopt the plan.
Additionally, in Region 1 (EMEA) the second digital dividend (694 MHz to 790MHz)
was included at the WRC-2012, in the agenda of the next conference, which will be held
in 2015 (Resolution 232 (WRC-12)). Under the A.I.1.2, the member states of Region
1 (EMEA) must examine the results of ITU-R studies on the use of the 694 MHz to
790 MHz frequency band by the mobile service, except aeronautical mobile, and take
the appropriate measures. The debate is now focused on how to allocate this spectrum
to achieve the best economies of scale and harmonization within the region and with the
countries adopting the APT700 band plan.
Figure 3. Near global harmonization possible with APT700 (Band 28)
C
CITEL
ATU
ASMG
CEPT
APT
ITU region 2
ITU region 1
ITU region 3
US Band Plan
Band 28 decisions/preference
Band 28 possible
Source: GSMA, Feb 2013
Lower 2 x 30 MHz for ITU region 1, 2 x 45 MHz for regions 2 and 3 (upper 30 MHz for Japan)
APT Asia Pacific Telecommunity
ASMG Arab Spectrum Management Group
ATU African Telecommunications Union
CEPT Conférence Européenne des administrations des Postes et des Télécommunications
CITEL Comisión Interamericana de Telecomunicaciones
7. APT700 – An Effective Band for Global Harmonization
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Alcatel-Lucent is aligned with the industry’s point of view, and we believe that, as
mobile broadband becomes the main broadband delivery mechanism in the world,
harmonization is playing an important role globally for the following reasons:
Absence of harmonization (within a given region or among regions) can lead to
fragmented markets. This could result in significant reductions in the take-up of
any mobile service due to prohibitive handsets costs.
Harmonization will allow mobile operators and manufacturers to address large markets
more efficiently, by achieving economies of scale for equipment manufacturers that
produce both network equipment and mobile terminals.
The propagation characteristics of spectrum below 1 GHz make the 700 MHz UHF
digital dividend band very suitable for wide coverage provision. This UHF spectrum is
also very well suited to in-building coverage provision, for example, in urban areas.
2.4 Device availability
The device ecosystem for the APT700 band (Band Class 28) is still evolving. Key specifics
concerning the Band Class 28 application-specific integrated circuit (ASIC) solution
include the following points:
Today Qualcomm is the only chipset vendor that has enabled an LTE Band Class 28
chipset to support LTE multimode devices for different form factors. Data solutions
include USB dongles, indoor and outdoor CPEs and Mi-Fi hot spots; and high-end
devices including smartphones and tablets.
Several other ASIC vendors are currently developing the APT700 band and plan to
commercialize this band in the 2014 timeframe. Tier 1 ASIC vendors include Intel,
Renesas and Samsung. Tier 2 vendors include Altair, Broadcom, GCT and Sequans.
The lack of chipset solutions for the APT700 band is attributed to the lack of carrier
LTE deployments globally in this band. Main deployments are anticipated to start in
the second half of 2014 with commercial launches in 2015.
Device availability for the APT700 will be driven by chipset availability and carrier
commitments within the Latin America and APAC regions.
The current indication is that test devices for the APT700 band will be available from
selected Tier 2 original equipment manufacturers (OEMs), including Bandrich, BEC
Technologies, Franklin Wireless, Gemtek, and Quanta, in early 2014, with commercial
devices targeted for end of Q1/early Q2 2014 timeframe.
High-end solutions (including smartphone and tablets) from Tier1 OEMs are currently
targeted for 2Q/3Q 2014. These solutions will be driven strictly by LTE deployment
timelines and volume commitments from key carriers (within Latin America and APAC
regions) that are deploying this band.
3. ADDRESSING SPECTRUM EFFICIENCY
The strong adoption of the APT700 band plan paves the way for economies of scale for
devices and network infrastructure, fosters improved spectrum efficiency and roaming,
and enables additional capacity to support new mobile broadband services.
3.1 The US digital dividend band plan
Given the advantages of this spectrum, the United States moved aggressively to develop a
plan for the band, with auctions taking place in 2008 and commercial launch of networks
in 2010 and 2011.
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At first glance, the US band plan seems to be the most obvious plan with which to
encourage alignment. However, the US band plan has its own deficiencies, which
include:
Interference between DTV Channel 51 and lower 700 MHz cellular systems
(See interference scenarios 1 and 2 in Figure 4.)
Interference between lower 700 MHz D Block and lower 700 MHz cellular systems
(See interference scenarios 3 and 4 in Figure 4.)
Interference between public safety narrowband (PSNB) and upper 700 MHz cellular
systems (See interference scenarios 7 and 8 in Figure 4.)
High-power, downlink-only broadcasts in E Block into A Block downlink
(See scenario 5 in Figure 4.)
Limited block sizes not conducive to 20 MHz channel LTE
Specific carve-outs for public safety
In Figure 4, interference scenarios 1, 3 and 7 are related to base station–to–base
station (BS-to-BS) interference. Since base stations have high antennas and could have
line of sight, the coupling loss from one BS to another BS could be much less than the
coupling loss between a BS and user equipment (UE). Therefore the impact of BS to BS
interference could be significant.
The BS-to-BS interference could be mitigated by implementing various techniques,
such as appropriate guard bands, BS transmitter emission mask improvements, receiver
selectivity enhancements and so forth. It should be noted that there is a trade-off among
the guard band, spectrum efficiency and filter insertion loss, roll-off, cost, size, weight
and waveform quality.
Interference scenarios 2, 4 and 8 in Figure 4 are related to UE-to-UE interference. Since
the UE-to-UE separation could be small in public transportation, such as trains and
subways, or hot spots such as airports and shopping malls, the coupling loss from UE to
UE could be much less than the coupling loss between BS and UE. Therefore the impact
of UE-to-UE interference could be significant. UE duplex transmit (Tx) and receive (Rx)
filters typically have a passband covering the whole band class (that is, multiple blocks),
and UE has size and cost limitations. As a result, UE may not provide sharp roll-off to
prevent interference with other UE receivers in other bands.
Figure 4. Potential interference among US 700 MHz broadcast, public safety and cellular systems
D
798768 775
TV
Channelization
698
MHz
TV
Broadcast
Interference
Scenario 1 Scenario 3
Scenario 2 Scenario 4 Scenario 6 Scenario 8 UL = Uplink
DL = Downlink
Scenario 5
A
52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69
B C B C A B C A B
710 722 728 734 740 746
757
769
787
788 793 799
805
806
MHz
Public
Safety
Narrowband
Public
Safety
Narrowband
Public
Safety
Broadband
Public
Safety
Broadband
A CD E
704 716 758 763
D
776
Scenario 7
DL DL DL DL DL DL UL UL ULUL
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The UE-to-UE interference issue could be alleviated using various techniques, such as
appropriate guard bands, UE transmitter emission mask improvements, receiver selectivity
enhancements, limiting the UE transmit bandwidth at the maximum power, over-
provisioning of Physical Uplink Control Channel (PUCCH) and additional maximum power
reduction (AMPR).
A substantial guard band may be required to minimize interference from UE-to-UE
interference. Potentially, this could be more than the guard band needed for BS-to-BS
interference mitigation.
The shortcomings of this US 700 MHz band plan can be summarized as follows:
Only up to 10 MHz channel bandwidth is supported by the 700 MHz LTE UE standard to
prevent UE self desensitization.
It is not possible to allocate larger carrier blocks in LTE, such as 20 MHz, because
the plan is too fragmented due to the guard band required to mitigate inter-system
interference. However, larger carrier blocks are essential for providing the highest spectral
efficiencies and highest throughputs per user.
The cost-per-delivered-megabit per second is higher, since optimal capacity-per-
megahertz cannot be achieved.
The cost, size and weight of cellular BS and UE Tx and Rx filters are increased in order to
alleviate BS-to-BS interference, UE-to-UE interference and interference between broadcast
and cellular downlinks.
The uplink LTE coverage, throughput or both could be reduced with AMPR.
The LTE uplink peak data rate could be reduced through over-provisioned PUCCH.
In Asia Pacific, the Asia-Pacific Telecommunity Wireless Group (now the APT Wireless
Forum or AWF), began considering how to make the best use of the digital dividend. Given
the “front runner” status of the US band plan, there was some impetus within the Asia
Pacific region to adopt the US band plan. However, after due consideration of the issues
described in this paper, there was no consensus to adopt the plan. The regional group
developed and adopted two consensus band plans that offered greater spectrum usage
and larger spectrum blocks, one FDD arrangement and one TDD arrangement.
3.2 The APT digital dividend band plan
FDD frequency arrangement
The Asia-Pacific region developed its band plan by taking into consideration the capabilities
of existing filter technology and aiming to maximize the amount of FDD spectrum. An FDD
plan with a 2 x 45 MHz FDD structure with a 10 MHz center-band gap was chosen.
A “conventional duplex direction” — with the lower block (703 MHz to 748 MHz)
allocated for mobile “uplink” transmissions — was adopted. This approach recognizes
the proliferation of Radio Navigation Satellite Service (RNSS) receivers in pedestrian and
vehicular environments and the risk of harmonic interference from user device emissions in
the 779 MHz to 805 MHz segment. Figure 5 shows the overall structure of the harmonized
FDD arrangement for the 698 MHz to 806 MHz band.
The dual-duplexer arrangement is needed to facilitate mobile terminal implementation,
while the overlap offers flexibility to administrations as they plan national spectrum.
(This topic is explained in greater detail in later sections of this paper.)
10. APT700 – An Effective Band for Global Harmonization
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It should be noted that in many Asia-Pacific countries the broadcast spectrum will be
cleared down to 694 MHz, due to the size of the TV channel rasters. So there will be
a guard band of up to 9 MHz on the bottom end.
TDD frequency arrangement
The TDD band plan also calls for a minimum internal guard band of 5 MHz at the lower
edge (698 MHz) and 3 MHz at the upper edge (806 MHz), in addition to the external
4 MHz guard band (694 MHz to 698 MHz).
3.3 ITU Digital dividend band plans
Recommendation ITU-R M.1036 recommends frequency arrangements for IMT-2000.
This document has been revised to include the three new band plans for the spectrum
698 MHz to 806 MHz. Table 1 contains these recommended 700 MHz band plans, which
are Band Plans A4, A5 and A6.
Table 1. Paired frequency arrangements in the 698 MHz to 960 MHz band
Frequency
arrangements
Paired arrangements Unpaired
arrangements
(e.g., for TDD)
(MHz)
Mobile station
transmitter
(MHz)
Center gap
(MHz)
Base station
transmitter
(MHz)
Duplex separation
(MHz)
A1 824–849 20 869-894 45 None
A2 880–915 10 925-960 45 None
A3 832–862 11 791-821 41 None
A4 698–716
776–793
12
13
728-746
746-763
30
30
716-728
A5 703–748 10 758-803 55 None
A6 None None None 698-806
Figure 5. APT harmonized FDD arrangement for 698 MHz to 806 MHz
DTTV
694
MHz
698
MHz
5
MHz
10 MHz
center gap
3
MHz
45 MHz 806
MHz
PPDR/LMR
45 MHz
Figure 6. APT harmonized TDD arrangement for 698 MHz to 806 MHz
806
MHz
PPDR/LMRDTTV
694
MHz
698
MHz
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4. TECHNICAL CONSIDERATIONS
As previously discussed, the APT700 band plan offers both economic and technical benefits
by helping to achieve global harmonization and economies of scale. The following sections
address the technical considerations involved when implementing networks within this band
plan.
4.1 Interference
Despite the APT700 band plan’s obvious improvement over the US plan, some challenges
associated with the Asia-Pacific FDD plan still remain, including:
Critical interference scenario from LTE UE transmitter to a DTV receiver (especially for
countries with 6 MHz TV rasters up to 698 MHz)
Critical interference scenario from land mobile radio (LMR) mobile transmitter to a LTE
UE receiver
Potential third-order passive intermodulation (PIM) with 850 MHz systems
One way that the Asia-Pacific plan addresses these challenges is through guard bands and
the use of dual duplexers. However, the arrangement of the dual duplexers still needs to
be finalized. Sub-band size and overlap will determine the various sub-band allocations
that administrations can allocate. For example, Figure 7 shows a 5 MHz overlap, with some
options for sub-band allocation following a 5 MHz raster. The smaller 20 MHz duplexer B
is the higher band, which helps relax requirements on the UE filters for protection of self-
desensitization across the 10 MHz center band gap. It also helps the base transceiver station
(BTS) filter for the sharp roll-off required for protection of any adjacent Public Protection
and Disaster Relief (PPDR).
Figure 7. Sub-band allocation options with APT 698 MHz to 806 MHz band plan
APT UHF (2x45 MHz, Conventional FDD)
Sub-band allocation options
698
MHz 703 728 748 758 783 788 803
806
733
45 MHz 10 MHz
5 MHz 3 MHz
45 MHz
A
10 MHz
A
10 MHz
A
10 MHz
B
10 MHz
B
5 MHz
A
20 MHz
B
20 MHz
A
5 MHz
A
15 MHz
A
15 MHz
B
15 MHz
A
5 MHz
A
15 MHz
A
10 MHz
B
15 MHz
A
5 MHz
A
20 MHz
B
10 MHz
B
10 MHz
A
10 MHz
A
10 MHz
A
10 MHz
B
10 MHz
B
5 MHz
A
20 MHz
B
20 MHz
A
5 MHz
A
15 MHz
A
15 MHz
B
15 MHz
A
5 MHz
A
15 MHz
A
10 MHz
B
15 MHz
A
5 MHz
A
20 MHz
B
10 MHz
B
10 MHz
Duplex B -
Uplink 20 MHz
Duplex B -
Downlink 20 MHz PPDR
UplinkDuplex A -
Uplink 30 MHz
Duplex A -
Downlink 30 MHz
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4.1.1 Digital TV
There are three digital terrestrial television broadcasting (DTTB) systems in the world. They
include Digital Television (DTV), developed in the United States; Digital Video Broadcasting
– Terrestrial (DVB-T), developed in Europe; and Integrated Services Digital Broadcasting-
Terrestrial (ISDB-T), developed in Japan. This section considers interference of APT700
with DVB-T and ISDB-T.
DVB-T
Interference can occur when IMT services (based on LTE) co-exist with digital TV systems
(based on DVB-T) adjacent to the lower end of the band. This can happen with either a
5 MHz or a 9 MHz guard band in the APT700 band plan. The potential interference
scenarios include:
Scenario 1: Interference from LTE UE transmitter to DTV receiver
Scenario 2: Interference from DTV station transmitter to LTE base station
Alcatel-Lucent conducted system-level probabilistic simulations, following the methodology
of TR36.942, with deviations for certain parameters agreed on by the AWG Correspondence
Group.2
The scenario we considered was for interference from LTE UE transmitters to 8 MHz
DVB-T receivers for Sub-Case b in a suburban area. That is, an outdoor LTE UE Tx
is interfering with DTV Rx with an outdoor rooftop antenna at a minimum distance of
10 meters.
Worst case assumptions were used for the LTE UE OOB emissions, power control
implementation and UE scheduling.
An adjacent channel interference ratio (ACIR) approach was used. However the LTE UE
adjacent channel leakage ratio (ACLR) (OOB emissions) levels dominated ACIR impact.
We observed that the 9 MHz guard band with 5 MHz LTE UE transmission bandwidth
case had negligible impact on 8 MHz DVB-T receive quality. In addition, in a realistic LTE
deployment, the number of simultaneously transmitting LTE user devices would not exceed
25, and the transmit bandwidth at the coverage edge would not exceed 5 MHz (25 RBs).
Therefore, we considered the corresponding UE OOB maximum emissions from this scenario,
which were –21 dBm/8 MHz, as an appropriate limit for protection of adjacent DVB-T
reception for all band scenarios. To account for other DVB-T system bandwidths in the region,
this level would translate to –21.4 dBm/7MHz and –22 dBm/6MHz.
2 AWG-11/INP-17
Figure 8. Potential interference among APT700 broadcast and cellular systems
DTTV
694
MHz
698
MHz
5
MHz
BTS Rx &
UE Tx
BTS Tx &
UE Rx
10 MHz
center gap
3
MHz
45 MHz 806
MHz
PPDR/LMR
and other
services
45 MHz
Interference Scenario 1: UE Tx to DTV Rx
Interference Scenario 2: DTV Tx to BTS Rx
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To maintain this limit for all LTE channels (up to 20 MHz), additional filter attenuation
of at least 13 dB would be required in the DVB-T receive band.
ISDB-T
A recent analysis conducted by the government of Japan examined interference between
a digital ISDB-T and IMT (uplink and downlink) in the 700 MHz band. The study con-
sidered protection ratios and overload threshold values for ISDB-T as noted in Table 2. A
comparison of these parameter values with those of DVB-T in the ITU-R Joint Task Group
4-5-6-7/126 revealed that the parameter values for DVB-T are similar to those for ISDB-T3
.
As a result, the sharing and compatibility studies based on DVB-T can also be applicable
to ISDB-T.
Table 2. Findings of a study examining protection ratios and overload threshold values for ISDB-T
Interferer offset
N/(MHz)
LTE base station LTE user equipment
PR (dB) Oth
(dBm) PR (dB) Oth
(dBm)
Co-channel (AWGN) 20.2 - 20.2 -
Co-channel (LTE) 20 - 19.5 -
1/(9 MHz) -22.5 -12 -4.2 -20
2/(15 MHz) -34.9 -10 -9.8 -17.5
4/(27 MHz) -36.2 -8 -32.5 -16
6/(39 MHz) -37.2 0 -50.1 -15.5
18/(111 MHz) -38.9 0 -46.9 -6
19/(117 MHz) -38.9 0 -45.8 -7
Note: PR and Oth values for a 6 MHz ISDB-T 64-QAM with code rate 7/8 signal interfered
with by a 10 MHz LTE base station or user equipment signal in a Gaussian channel
environment for all tuners and traffic loadings
4.1.2 LMR PPDR
Studies conducted in AWG during the development of the APT digital dividend band
plan focused on interference issues with the existing narrowband public safety systems
above 806 MHz. Those studies found that “Using the study from ECC Report 131 as a
basis, it appears feasible for the 806 MHz to 894 MHz frequency to be used for mobile
broadband services including for PPDR applications.”4
4.1.3 Cross-border (US band and APT band)
Along the US-Mexican border, inconsistencies between the US and APT700 FDD band
plans will cause interference requiring carefully coordinated radio planning to mitigate.
The difficulties are evident in the comparative band plan shown in Figure 9. It illustrates
the US band plan with 3GPP bands 12, 13, 14 and 17 on the top. The APT700 FDD Band
28 plan appears below. Between them, the frequency regions of particular interference
concerns are shown as arrow where the US downlink is on the same frequencies Mexico
uses for uplink (between 716 MHz and 748 MHz). So existing US base stations transmit
directly on frequencies the Mexican base stations will otherwise use for uplink reception.
The spectrum from 776 MHz to 803 MHz has Mexican base stations potentially injecting
co-channel interference into base station receivers on the US side of the border, as
3 Document 4-5-6-7/146
4 AWG-11/INP-23
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well as into some public safety fixed receivers. These regions of spectrum require close
coordination of base station placement and antenna orientation to reduce the incidence
of interference. At a minimum, some “buffer zone” is needed where the operator in
one nation’s system would be overly desensitized by co-channel interference from base
stations across the border. Negotiation between operators can benefit everyone, because
the harm is reciprocal. Judicious down-tilting of antennas near the border would be
helpful, as would placing antennas near the border but directed toward the serving areas,
probably with fewer sectors than normal, as shown in Figure 10. The figure (which is
not to scale) illustrates two-sectored towers near the border and conventional three-
sectored antennas far from the border. Operators may also place smaller cells near the
border, and indoor cells may be located particularly close to the border. In this case, the
building-penetration loss contributes helpfully to the antenna isolation needed to obtain
an agreed-upon desensitization level.
Figure 10. Mitigating co-channel interference along the border through careful RF planning
Border
There are ranges of frequency where the uplink-downlink orientation will be the same
on both sides of the border, as shown in Figure 9 (703 MHz to 716 MHz for uplink and
the US public safety downlink blocks). This is not helpful to the US C Block operator, but
the Mexican operator in the lower 13 MHz of the spectrum will benefit. Some co-channel
interference will still occur, approximately the same degree of interference that arises
near any service area boundary. In these cases, operator coordination of power-flux
density, at ground level near the border region, can be agreed upon and controlled
through antenna orientation. Unfortunately, because the channelization is not exactly
Figure 9. Potential interference between US and APT700 band plans
DTV 5 MHz Uplink Downlink PPDR/LMR
694 698
698 704 710 716 722 728 740 746 752 758 764 770 776 782 788 794 800 806734
703 748 803
704 710
Filter 1
45 MHz 10 MHz
duplex
PPDR/LMR
Up
Only the worst
cases of interference
are highlighted.
Mobile uplink transmissions Base Station Transmissions
Filter 2 Filter 1
45 MHz
Filter 2
716 722 728 734 740 746 752 758
758
764 770 776 782 788 794 800 806
Band 28 (APT band for Mexico)
US Band plans for 700 MHz
Channel #
US Plan
3GPP Plan
Direction Uplink
A B
Band 17 Band 29 Band 17
Band 12 Band 12
Band 13 Band 14 Band 13 Band 14
D E A B C C PS BB CPS NB C PS BB PS NBC
Downlink Downlink Downlink Uplink Uplink
A B A B
52 53 55 56 57 58 59 61 62 63 64 65 66 67 68 696054
InterferenceInterference
In accord In accord
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the same, and bands are different, one country’s UE may drag a call into the neighboring
country without intersystem handoffs to return the terminal to the lowest transmit
power levels.
Adjacent channel interference can arise across the border, as shown in Figure 11.
Through careful analysis of these adjacent channel interference (ACI) cases, we
have found that the standard Adjacent Channel Leakage Ratios (ACLR) and Adjacent
Channel Selectivity (ACS) are such that the buffer regions needed to protect against
ACI are smaller than the buffer region needed to protect against co-channel interference
considered earlier. In addition, the restrictions on the channels that are “in accord” limit
the bandwidth of operation to 10 MHz uplink in filter 1 (703 MHz to 713 MHz) and,
provides an additional guard band, protecting against adjacent channel leakage into the
other country’s system.
Currently, these co-channel interference scenarios are not insignificant, and negotiations
are made more difficult by the substantial existing deployment of systems on the US side.
However, the reciprocity of the interference should motivate negotiations as the Mexican
spectrum is put to use, and coordination of the radio network planning can proceed
among the operators. The increasing availability of small cells (Alcatel-Lucent metro cells
and indoor cells) provides new and very useful tools for radio planning and should help
mitigate the size of the exclusion zones near the border.
Alcatel-Lucent’s use of frequency selective scheduling (FSS) tends to mitigate interference
by scheduling physical resource blocks (PRBs) that are somewhat “orthogonal” to those
of an interfering source that may overlap the channel. Some important interference
mitigations have used “over provisioned PUCCH” to reduce ACLR in bands with
particularly onerous emission leakage regulations.
In addition, Alcatel-Lucent has spearheaded research in interference rejection combining
(IRC) to greatly reduce interference in the uplink, by making use of multiple receiver
diversity branches. The direction of arrival (DOA) of noise (or more generally the spatial
noise covariance among antenna columns) is used to solve the minimum mean squared
error (MMSE) criterion to derive the complex weights on the multiple antenna columns,
essentially steering nulls toward interfering sources. This method helps optimize the
signal to interference plus noise ratio (SINR) by reducing the interference, “I,” as well
as increasing the signal, “S.” It is distinct from the Maximum Ratio Combiner which
optimizes the SNR only.
Figure 11. Adjacent channel interference scenarios
798768 775
USA
Band
Plan
APT
Band
Plan in
Mexico
TV
Channelization
698
MHz
A
52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69
B C B C A B C A B
ACI from BS to
BS (Scenario A)
ACI from BS to
BS (Scenario C)
ACI from
UE to UE
(Scenario D)
ACI from UE to
UE (Scenario E)
ACI from BS to
BS (Scenario F)
ACI from UE to
UE (Scenario B)
710 722 728 734 740 746
757
769
787
788 799 805
698
MHz
703 748 758
803
806
Public
Safety
Narrowband
Public
Safety
Narrowband
Public
Safety
Broadband
PPDR
Public
Safety
Broadband
A CDTV
DTV
D E
704 716 758 776
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There may be other cases where FDD and TDD versions of the APT700 bands are used
in adjacent countries. However, the economics have favored FDD systems, reducing
the number of instances of this discrepancy, for example, to regions along the Chinese
borders.
Troublesome cross-border interference issues may be dealt with using the tools and
methods just discussed to efficiently minimize the buffer zones with the acceptable
performance penalties.
4.1.4 GPS
As mentioned in section 3.2.2, the APT700 FDD band plan places the downlink in
the spectrum from 758 MHz to 803 MHz. Harmonics from these powerful downlink
signals can be a concern for operations in the lower L band (second harmonic) and
the SDARs band (third harmonic) where Sirius-XM have international operations. The
second harmonic is of particular concern for signals in the upper filter 2 duplexer region,
because it includes the GPS Radio Navigation Satellite Services (RNSS). These sensitive
receivers are tuned to listen to very weak satellite signals centered at 1575.42 MHz and
with substantial bandwidths of many megahertz. Moreover, these receivers are often
used in close proximity to mobile handsets and may even be built inside the same
smartphones.
This is a design challenge for the upper C Block terminals used in the United States.
However, with care and by sampling the GPS receiver during those time slots when
the UE is not transmitting, adequate performance can be obtained. The larger power
levels used in the base stations tend to generate correspondingly larger harmonic
products, if care is not taken in the connection and installation of base station radios
and their antennas. Passive harmonic generation from poor connectors, water ingress
or even “rusty bolts” on the antenna mounts and structure have been found to generate
deleterious harmonic products. Provided that good installation practices are followed,
however, this should not be a problem, particularly for conventional macro cells with
antennas that are some distance from the GPS receivers. Metro cells and other small cells
must be considered carefully, so that they are not mounted too close to locations where
GPS receivers may need to operate.
In sum, when compared with the US plan, the APT700 plan:
Significantly reduces the DTV interference concern
Improves the interference scenario with PPDR
Manages the harmonic interference issue with GPS receivers
Offers larger bandwidth to facilitate LTE deployment up to 20 MHz FDD or TDD
channels
Potentially delivers respectable economies of scale, especially if Japan also manages
to clear the 698 MHz to 806 MHz range
Mitigates self-desensitization by employing the dual duplex band plan to increase
the duplex gap
The APT700 plan does not completely eliminate the challenges described here. However,
it does significantly reduce their impact. Careful consideration and planning must, as
always, be used when deploying systems according to this plan.
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4.2 Global roaming
To take into account the needs of African and Arab states, the recent World Radio
Conference (WRC-12) extended the Region One (Europe, Africa and the Arab States)
mobile allocation to allow for IMT (790 MHz to 862 MHz). Essentially the conference
expanded the Region One allocation to include the Region Three (Asia Pacific - APT)
allocation (698 MHz to 804 MHz).
Since the WRC-12 decision, many European operators and administrations have
been arguing that the APT700 plan for Region Three should now be modified to take
into account the two Region One mobile allocations. Figure 12 shows one suggested
arrangement.
Figure 12. Suggested modification to the two band plans
703 733 758 788
718 748 773736 791 803
791 821 832 862
APT ‘A’ - lower APT ‘A’ - upper
APT ‘B’ - lower APT ‘B’ - upper
CEPT - lower CEPT - upper
Harmonization of the APT700 band plan within the Caribbean and Latin America
(CALA) region is essential for intra-region roaming purposes. In Mexico, most visitors
and roamers are from the United States, but in other countries, the bulk of visitors and
roamers come from within CALA and from Europe, as shown in Table 3.
Table 3. Visitors and roamers’ origin for CALA’s five largest countries
Percent of Visitors
and Roamers
Brazil Mexico Colombia Argentina Peru
CALA 34% 2% 56% 55.5% 38%
NAR 15% 83% 27% 16.0% 19%
EU 32% 14% 17% 14.0% 32%
APAC 1% 1% 0% 1.5% 6%
Others 18% 0% 0% 13.0% 5%
Total 100% 100% 100% 100% 100%
There are then three different cases to support roaming into the CALA region:
Roamers from the United States and Canada will use the US band plan.
Roamers from APAC will use the APAC band plan.
Roamers from Europe will use the 800 MHz band.
It will be challenging to have terminals supporting all the different band plans for the
lower LTE frequencies. At some point, terminals will probably support both the US and
the APAC700 band plans, but this will increase terminal complexity and cost.
Based on the data in Table 3, APAC roamers into CALA are limited, so roaming is not a
major driver of the band-selection decision. However, adoption of the APT700 band plan
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within CALA would clearly help cut down on device costs, offer operators more spectrum and
limit the interference issues that may arise with the US band plan.
Most of inter-regional roaming will not be achieved through the use of terminals supporting
two or three different band plans for the lower frequencies, but rather through other bands,
such as the AWS band for roamers from the United States and Canada and the 1.8 GHz and
2.6 GHz band for roamers from other countries. The 1.8 GHz and 2.6 GHz band will surely
play a major role for international roaming and should be supported by most devices.
4.3 Dual duplexers in terminal equipment
Duplex filters are needed to isolate the transmit and receive signals, saving the sensitive
low-noise receive amplifier (LNA) from being overloaded or desensitized by the strong
transmit signal. They also help reduce out-of-band emissions from the transmit chain to meet
regulatory requirements reducing interference with other products in other bands. Ideally, the
duplex filter’s receive side would pass the entire 45 MHz receive band and the corresponding
45 MHz transmit band as is done in the base station.
Unfortunately, among the current filter technologies appropriate for handsets and tablets,
duplexers are limited to operating over no more bandwidth than about 3.5 percent to
4.2 percent of the operating frequency.5
This corresponds to bandwidth no greater than about
26 MHz to 30 MHz, due to the material limitations of modern Surface Acoustic Wave (SAW)
and Film Bulk Acoustic Resonators (FBAR) filters. Because of these limitations, UEs will
implement Band 28 with two sub-bands corresponding to the two overlapping filters shown
in Figure 7.
The sub-bands also make the duplex gap easier for the filters in the UE to handle. So, instead
of a 10 MHz duplex gap, each of the two duplexers has an easier transition of 25 MHz
(758 MHz to 733 MHz). As a result, the filter is smaller and somewhat lower in cost than
those needed in the US band plan. This approach promotes the goal of having all Band 28
UEs equipped with both duplexers and supporting the entire APT700 band, thus providing for
global roaming, including roaming among operators, and UE versatility. This larger ecosystem
of dual-duplexer RF front-end modules (FEMs) helps to reduce costs further. (Doubling the
quantity of units of the same model tends to reduce costs by about 18 percent.6
)
4.4 Antenna size
Like filters, antennas are limited in their usable fractional bandwidths. If handset antennas
are made to operate over a fractional bandwidth in excess of about 10 percent to 12 percent,
then efficiency drops substantially. Some modern handset antennas compensate for this
somewhat by often using a different feed point for transmit and receive bands. More recently,
some tuning networks load the antenna differently for different channels of operation to
essentially “retune” the antenna for whatever part of the band is in use. In these ways,
the entire 700 MHz band can be served with a single antenna structure for each of the two
diversity paths required of LTE terminals. For receive diversity, the handset uses two of the
antennas, which are roughly about l/4 in size (for a quarter-wave monopole.) This is about
100 mm in length, which fits nicely on the two sides of a mobile phone.
5 IWPC Mobile RF Filter Group filing of Don Brown, November 27, 2012, FCC in Docket No. 12-268, http://apps.fcc.gov/ecfs/document/
view?id=7022066310
6 Epple, 1990
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5. ALCATEL-LUCENT APT700 SOLUTION
As a global leader in LTE, Alcatel-Lucent is developing solutions that take full advantage of
the APT700 band plan.
5.1 Solution component overview
Alcatel-Lucent has built the world’s largest and busiest LTE networks in record time and
has the experience to get operators to market fast. Our wireless IP solutions and lightRadio™
Network portfolio has enabled operators to deliver an ultra-broadband experience with the
capacity and dedicated performance needed now and into the future. Our global leadership
in wireless and wireline technologies such as IP backhaul and transport solutions, small
cells and LTE allow operators to stay ahead at every step,
and our services ensure fast, right-the-first-time deployments.
Alcatel-Lucent is committed to the APT700 band plan with products supporting this band
becoming commercially available in 2014. The Alcatel-Lucent LTE solution includes a full
range of products supporting macro cells, metro cells, enterprise cells and residential cells,
with the aim of providing capacity and coverage while achieving higher spectrum utilization
and an improved user experience.
To ensure early availability of an end-to-end LTE solution, including the network and
associated devices, Alcatel-Lucent has developed strategic partnerships with multiple device
solution partners, including ASIC vendors and device OEMs. These partnerships will help
enable LTE multimode devices (FDD and TDD) for global carriers.
To enable a wider device ecosystem for the APT700 band, Alcatel-Lucent will perform the
required interoperability of the vendor ASIC platform with the Alcatel-Lucent infrastructure
as chipsets become available. Alcatel-Lucent will execute testing, as required by the carrier
for the customer’s preferred devices, to ensure interoperability testing (IOT) compliance and
availability of an end-to-end LTE solution for the APT700 band.
5.2 Solution benefits
Alcatel-Lucent is at the forefront of macro cell and small cell innovation. In anticipation
of the APT700 band plan, new radios will support operators that choose to deploy in this
spectrum. These radios leverage unique capabilities specific to this band plan. For instance,
the Remote Radio Head (RRH) filter has a unique ability to address the full band (45 MHz)
in a single radio. As a result, it avoids the space requirements and costs associated with
multiple radios that can only satisfy part of the spectrum band. For example, three carriers
of 15 MHz can be implemented on a single radio.
The radios also provide four receive branch diversity to enable better coverage and lower total
cost of ownership. In addition, by avoiding interference through the use of new filters, the
radios enable co-existence with other bands, including GPS, Wi-Fi, Band 26 and other high-
band radios, allowing for flexible deployments. As with other RRHs, the compact size enables
deployments closer to the antennas, which reduces signal loss and requires less power. An
innovative design also allows the new platform to evolve to support other bands, like 800EDD
or future European bands making use of common assets. It can also support other form
factors, that is, transmit receive duplexer unit (TRDU), higher power amplifiers and evolution
to LTE TDD, making the solution quite flexible for different deployment scenarios.
