spectrum considerations for emergency mobile radio backhaul john yaldwyn – cto
TRANSCRIPT
Spectrum Considerations for Emergency Mobile Radio Backhaul
John Yaldwyn – CTO
Australia is a big place
It is common in land mobile radio systems to
concentrate on the radio spectrum requirements of the
air interface between users terminals and base
stations.
Often an implicit assumption that there is some form of
invisible backhaul ‘cloud’ connecting base station sites.
In the past fixed line circuits leased from Telstra and
analog UHF duplex links were used to backhaul radio
systems.
Today, as the world moves towards a total IP form of
implementation, new technology backhaul solutions
are required.
However there is one constant – the need for backhaul
spectrum.
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LMR networking today
Legacy 4-wire analog and TDM E1/T1 interfaces have
rapidly given way to IP over Ethernet interconnection.
Mid-tier digital LMR such as Motorola Mototrbo™ and the
Icom/Kenwood NEXEDGE™ systems feature IP based
network interconnection.
High end public safety Project 25 digital LMR systems
from most vendors now support the P25 Inter RF
Subsystem Interface (ISSI) enabling agencies to be
interconnected. Same systems connections are
transitioning from typically 9K6 serial to IP.
IP and the Ethernet interface have become unifying
standards for interconnection of LMR networks.
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IP backhaul for public safety
IP interconnections provide the basis for
information sharing and interworking of
decision support tools at control and incident
management centres. With care digital LMR
systems can also be linked over the same
network infrastructure.
IP networking will increasingly allow shared
network use supporting new response tools
such as video and PDA type applications.
Effective IP backhaul needs to be available
for remote and rural Australia.
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Backhaul network topology and ownership
Both point to point and point to multipoint microwave
backhaul options exist. These two complementary
topologies offer a range of network architectural choices:
• P-P established approach with distance - capacity
trade-off and wide range of vendors.
• P-MP to date proprietary but great promise from
WiMAX and other standards based solutions. More
limited range for given constraints.
Intuitively would always opt for P-MP flexibility but real
world issues mean a blend of approaches is often best.
Mesh systems appear attractive but capacity and QoS
need careful evaluation.
Who will own your backhaul and what are their day to
day priorities?
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Backhaul frequency choices
Backhaul networking technology need to be
appropriate to the problem being solved.
City and metro areas have a large range of
implementation options available including
short haul microwave (7+ GHz) radio, fibre, or
leased line.
In remote areas long haul digital microwave
radio is the method of choice. Such systems
operate in lower microwave spectrum below
3 GHz and offer impressive NLOS capabilities,
but spectrum is scarce. Suitable spectrum is
limited and must be carefully maintained.
Unlicensed radio frequencies are not
appropriate for safety of life systems.
Backhaul network issues
Capacity
Range
Site acquisition
Spectrum availability
Physical infrastructure
Reliability and security
Installation and maintenance
Interference
Cost
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Flexibility and ease of use
Free standing tower
Wooden pole
Simple grid type and Yagi antennas can be used in the sub
3GHz bands instead of the solid parabolic antennas used at
higher bands, with significant cost and time benefits:• Expensive self supporting towers can be replaced by
cheaper pole mounts or guyed masts• With minimal support needed, site acquisition can be
simpler and done more quickly
Grid type and Yagi antennas are significantly less affected by
wind forces than solid types reducing the need for supporting
structure stiffness. Costs are greatly reduced.
FST
FAT
MT
FST
MT
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400 MHz band SCTF
Single channel two frequency (SCTF) fixed links ACMA
FX17:
•High/Medium Spectrum Density requires antenna with good F/B
ratio (Yagi)
•Outside these areas a low cost Yagi will be adequate
•25 kHz channels
•112 kbps @ 64 QAM
•Ideal for analog LMR and digital P25 backhaul
•Lowest cost backhaul radio system
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900 MHz band SCTF and LCTF
Single channel two frequency (SCTF) fixed links
ACMA FX17:
•High/Medium Spectrum Density requires antenna with good
F/B ratio (small grid or two stacked Yagi)
•Outside these areas a low cost Yagi will be adequate
•25 kHz channels
•112 kbps @ 64 QAM
•Ideal for analog LMR and digital P25 backhaul
Low Capacity Two Frequency (LCTF) fixed links
ACMA SPP 6/93:
•2M notional antenna
•50, 100, and 200 kHz channels
•256, 400, and 1,024 kbps @ 64QAM
•Ideal for P25 and Tetra backhaul
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1.5 GHz band
World’s most popular low capacity link band
1427 -1535 MHz:
• 20 km minimum path length
• 1.8M grid style dish minimum
• 4 MHz channels
• 17 Mbps @ 64QAM
• 240 km links in use for public safety
• Superb combination of capacity vs cost
Restrictions:
• Telstra DRCS use - obsolete
• Digital satellite broadcasting – it will never happen
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2.1 and 2.2 GHz bands
Excellent band for medium capacity
links in remote area.
ITU proposals for IMT upset use and
caused a decade of uncertainty - now
resolved.
2.1 GHz overlaps IMT / LTE allocation
so not recommended for new uses.
2.2 GHz band Embargoed from 1994,
from 2005 remote density area use OK:
•20 km minimum path
•3M notional antenna
•14 MHz channels
•65 Mbps @ 64QAM
New threat - ENG IFC01/10
Sub
band
(MHz)
LTE E-UTRA band Description
1900 –
1920
Band 33 TDD / top band
39 TDD
TDD Region 1 & 3
PCS extension Region 2
(TDD 1900)
1910 –
1930
Band 37 TDD TDD Region 1 & 3, PCS
centre Region 2
1920 –
1980
Band 1 uplink 3G UMTS uplink Region
1, 2 & 3
(IMT core)
1930 –
1990
Band 2 downlink / band
36 TDD
3G UMTS uplink Region
1, 2 & 3
(PCS / TDD 1900)
1980 –
2010
NOT USED Mobile satellite phone
services uplink
(subject to WRC-11)
2010 –
2025
Band 34 TDD 3G UMTS TDD Region 1
& 2 (TDD 2000)
2025 –
2110
NOT USED Space services –
operations and earth
exploration
Fixed service links
(ITU-R F.1098 & T/R 13-
01 E Annex C)
2110 –
2155
Band 4 downlink 3G UMTS downlink
Region 1, 2 & 3
(AWS USA downlink)
2110 –
2170
Band 1 down / band 10
down
3G UMTS downlink
Region 1, 2 & 3
(IMT core)
2170 –
2200
NOT USED Mobile satellite phone
services downlink
(subject to WRC-11)
2200 –
2290
NOT USED Space services –
operations and earth
exploration
Fixed service links
(ITU-R F.1098 & T/R 13-
01 E Annex C)
2300 –
2400
Band 40 TDD 3G UMTS 2.3 TDD
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Existing long haul 2 GHz link
Remote Area LMR Base Urban Area HQ
ACMA IFC01/10: … fixed links operating over long distancesmay require replacement by two links in the alternativebands to achieve the same distance.
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New sites and new radios
Urban Area HQRemote Area LMR Base
Higher bands = short links and more sitesMore sites = higher backhaul costs
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ACMA
Section 3b of the object of the Radiocommunications Act 1992 requires the ACMA to make adequate provision of spectrum for use by public safety.
The Act does not define how ACMA should determine how much spectrum is ‘adequate’.
ACMA “does not consider it possible or appropriate to provide a general definition of adequate provision”.
•From ACMA March 2009 Response to submission on the draft spectrum management principles
There are many complex ways to attempt to measure adequacy:
•ACMA chooses the total welfare standard to assess public interest …
•Total welfare is a competition policy theory, one of them at least
•Some argue the true consumer welfare standard gives better outcomes
The key is whose welfare is to be measured?
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ACMA engagement
Public safety is the public’s safety
There is one simple way to draw attention to public safety needs …
Public safety spectrum requirements must be clearly
articulated to ACMA.
Public safety agencies must ensure that all
opportunities to engage with ACMA are addressed
and exploited.
There are 4,000 licences issued to 260 users of 900
MHz and 1.5 GHz but feedback from ACMA
indicates these users are not talking.
Make sure you do!
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Talk to the ACMA about spectrum for backhaul!
Rural and remote Australia
17
26 GLOVER STREET
NGAURANGA
WELLINGTON 6035
NEW ZEALANDTELEPHONE +64 4 499 6000
FACSIMILE +64 4 473 4447
EMAIL [email protected]
URL www.4rf.com
Thank [email protected]