Transcript Results of Operational Compatibility Studies between ASR, Meteorological Radars and IMT Systems Operating in the 2 700 – 2 900 MHz Band Presented By: Robert.

Results of Operational Compatibility Studies
between ASR, Meteorological Radars and
IMT Systems
Operating in the 2 700 – 2 900 MHz Band
Presented By:
Robert Leck
NOAA’s National Weather Service
(QSS Group Inc. for NOAA/NWS)
January 2007
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ARS and Meteorological Radars
Overview
 Meteorological Radar Frequency Band
 Meteorological Radar Coverage
 ASR Coverage
 2700-2900 MHz Band Utilization

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Overview

The 2700-2900 MHz Band is used on a global basis by
both ASR and meteorological radars

NOAA operates a wide network of meteorological Radars.

Interference to meteorological radars from IMT systems
degrades the radars performance.

Simulations verify potential problems and establish if
compatibility between systems is possible.
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ASR and Meteorological
Radar 2700-2900 MHz Band
Radio Regulations Footnote 5.423- In the band 27002900 MHz, ground based radars used for
meteorological purposes are authorized to operate
on a basis of equality with stations of the
aeronautical radionavigation service.
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2700-2900 MHz Band Utilization
NOAA NWS NEXRAD Network
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2700-2900 MHz Band Utilization
FAA Radar Network
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2700-2900 MHz Band Utilization
Current Radar and Potential Base Station Deployment
ASR Radar
Deployment
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Meteorological Radar
Deployment
Typical Base Station
Deployment
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2700-2900 MHz Band Utilization
RF Survey
Frequency Domain Representation of the 2700-2900 MHz Band within an
Urban Environment (Los Angeles, California)
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Meteorological Radars
Base Products
 Interference Criteria
 Effects of Interference Upon Radar
Performance

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Meteorological Radar Base
Products

Modern meteorological
radars measure reflectivity,
velocity and spectrum width
– Reflectivity: return signal level
used to measure total water in
sample volume
– Velocity: measure of speed and
direction of movement of the
atmosphere
– Spectrum Width: measurement
used to determine turbulence and
wind shear
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ASR and Meteorological
Radar Interference Protection
Criteria

The ITU-R has established an I/N of -10 dB for ASR
and meteorological radars. (ITU-R Recommendation
M.1464)

Additional testing to determine if an I/N of -14 dB can
be justified is being planned for 2007.
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Effects of Interference on
Radar Performance

Presence of interference:
– Raises the radar noise floor making it less sensitive to very
weak return signals
– Increases intensity of reflectivity measurement resulting in
overestimation of atmosphere moisture content and rainfall
– Corrupts base data products used for measuring wind
– velocity, turbulence, wind shear, and tornado detection
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Example of Interference on
Radar Operations
No Interference
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Interference
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IMT Systems

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What is IMT ?
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What is IMT?

IMT encompasses both IMT-2000 and IMT-Advanced
Systems
–
–
–
–
Intended to provide seamless worldwide mobile
telecommunications (voice and high speed data)
Use one band plan worldwide
Use a common radio standard for worldwide mobility

Worldwide compatibility standards development
being led by ITU

Seeking spectrum in various frequency ranges
including the 1-3 GHz range
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Simulations
Study/Simulation Objectives
 Simulation Criteria
 IMT Cell Topologies

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Study/Simulation Objectives

To combine and summarize the results of several
different studies regarding sharing of the 2 700 – 2
900 MHz band between various radar (ASR and
meteorological) and IMT systems.

To conduct new simulations that provide insight into
the feasibility of sharing the 2 700 – 2 900 MHz band
between ASR and meteorological radars and IMT
systems.

Based upon the results of those studies, develop
conclusions regarding the compatibility of those
systems when jointly operated within the 2700-2900
MHz band.
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Simulation Criteria

The simulation was conducted using propagation
characteristics and terrain modelling simulations that
were based upon a software implementation of ITU
Recommendation ITU-R- P.452-12.

IMT system characteristics were taken from ITU
Recommendation ITU-R M.2039

Radar characteristics were taken from ITU
Recommendation ITU-R M.1464 and ITU-R M.1461
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Simulation Criteria

The simulations were configured to closely
approximate the operation of the radar.

IMT topologies included macro, micro and pico cell
deployments.

The predominant interfering element in an IMT
network is the IMT base station.
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Simulation Criteria

The interference simulations were run under two
scenarios.
– The first scenario had the radar placed at the edge of the cell
coverage area.
– The second scenario varied the distance from which the
radar was offset from the cell coverage area.
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Macro Cell Topology
Radar is Offset from a Macro Cell Service Area
Service Area
75 km
75 km
Radar
Separation
Distance
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Micro Cell Topology
Radar is offset from Micro Cell Service Area
Service Area
10 km
Radar
10 km
Separation Distance d
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Pico Cell Topology
Radar is offset from Pico Cell Service Area
Service Area
Radar
Separation Distance d
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Simulation Results
IMT to Meteorological Radars
 Meteorological and Airport Surveillance
Radars to IMT Systems
 Multiple Meteorological and Airport
Surveillance Radars to IMT Systems
 Conclusions

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Simulation Results
IMT to Meteorological Radars
I/N (dB) vs. Separation Distance
Type G Meteorological Radar - IMT Micro Cell Base Station Cluster
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I/N (dB)
40
20
0
-20
I/N = -10 dB
-40
-60
0
100
200
300
400
500
600
700
800
Separation Distance (km)
Micro I/N (dB)
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Macro I/N (dB)
Pico I/N (dB)
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Simulation Results
IMT to Meteorological Radars

Results have shown that a minimum separation
distance of 500 km between Meteorological radars
and IMT networks is necessary to protect radar
operations
– Even with separation distances in excess of 500 km, the
meteorological radar I/N Protection Criteria as defined by the
ITU cannot be met.

Studies have shown that interference from IMT
macro, micro and pico based topologies within the 2
700 – 2 900 MHZ band will impair Airport Surveillance
Radars and Meteorological radar operations.
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Simulation Results
Meteorological and Airport Surveillance Radars to IMT Systems

Interference from radar pulses has the potential to
degrade IMT receiver performance via a number
mechanisms including
– LNA overload
– Saturation of the automatic gain control (AGC)
– Interference to signal ratios beyond the dynamic range of the
analog to digital converter (ADC)
– Filter overload
– Mixer overload.
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Simulation Results
Meteorological and Airport Surveillance Radars to IMT Systems

Simulation results showed co-channel operation
interference can occur even with large separation
distances between Airport Surveillance Radars,
Meteorological Radars and IMT systems.
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Simulation Results
Meteorological and Airport Surveillance Radars to IMT Systems

The ITU specified interference protection criteria for
IMT Base stations was shown to always be
exceeded at distances below 100 miles1.

Simulations indicated that widespread jamming of
mobile and base station units would take place
within the operational range of the radars.
(1) Propagation effects (multipath, fading, terrain, etc.) could result in received signal
levels from the radar that are higher than those predicated by path loss
extending this distance even further.
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Simulation Results
Multiple Meteorological and Airport Surveillance Radars to IMT Systems

The LNA in the handset will, at times, be operating
at or above its 1 dB compression point.
–

This will result in the potential desensitizing of the IMT
receiver and loss of service.
Base and Mobile station receiver LNA's can, at
times, be subjected to high levels of RF energy.
–
These levels can damage sensitive components in the
base and mobile station receivers, effectively disabling
multiple service areas.
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Potential IMT System
Degradation
Loss of service
 Dropped calls
 Damage to sensitive receiver
electronics
 Poor quality of service
 Limited deployment potential

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Conclusions
IMT to Meteorological and Airport Surveillance Radars

RF emissions from IMT transmitters would
necessitate separation distances in excess of
500 km in order to ensure that radar receiver
protection criteria are not exceeded .

Even if large separation such distances could be
tolerated, regions in which sharing could take place
would be severely limited due to the widespread
geographical deployment of multiple Meteorological
and Airport Surveillance Radars..
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Conclusions
Meteorological and Airport Surveillance Radars to IMT Systems

Radar signals, when present at the input to the IMT receivers,
can overload the receiver resulting in loss of service or, in some
instances, damage to the base station and or mobile unit.
– Even if the IMT service were offset in frequency from one
radar system, the IMT systems would still be interfered with
by other radar systems operating at different frequencies
throughout the band.

IMT receivers would be jammed, disabled or damaged by the
aggregate RF effect of the radar systems operating in that band.
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Conclusions
Meteorological and Airport Surveillance Radars to IMT Systems

Current IMT interference mitigation techniques would not protect
the IMT mobile or base station receivers from high power radar
signals.

In scenarios where the band use is limited to uni-directional
(Base Station to Mobile Station) transmissions only, the
separation distances required to protect the IMT receivers would
make the deployment of such a network impossible due to the
effect of the interference from the radars into the IMT mobile
stations.
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Conclusions
2700-2900 MHz Band Utilization

Studies have shown that IMT systems cannot operate with
radars in the same band.

IMT operation in 2700-2900 MHz will place unacceptable
operational restrictions on meteorological radar operations and
result in detrimental interference to the radars.

IMT receivers would be jammed, disabled or damaged by the
aggregate RF effect of the radar systems operating in that band.

The required separation distances for sharing of the band
preclude the effective deployment of IMT systems.

The overall results of the study show that sharing of the 2 700 –
2 900 MHZ band with IMT systems is not feasible.
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Recommendation
That IMT systems not operate within the same
geographical region[1] as Airport Surveillance and
Meteorological radars
[1] For purposes of this recommendation the same geographic
area is defined as within a 500 km radius of a radar operating in
the 2 700-2 900 MHz band.
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Thank You !
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