National Weather Service 1 Results of Operational Compatibility Studies between ASR, Meteorological...

1National Weather Service

Results of Operational Compatibility Studies Results of Operational Compatibility Studies between ASR, Meteorological Radars and between ASR, Meteorological Radars and

IMT Systems IMT Systems Operating in the 2 700 – 2 900 MHz BandOperating 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


ARS and Meteorological RadarsARS and Meteorological Radars

OverviewMeteorological Radar Frequency Band Meteorological Radar CoverageASR Coverage2700-2900 MHz Band Utilization


OverviewOverview 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.


ASR and Meteorological ASR and Meteorological Radar 2700-2900 MHz BandRadar 2700-2900 MHz Band

Radio Regulations Footnote 5.423- In the band 2700-2900 MHz, ground based radars used for

meteorological purposes are authorized to operate on a basis of equality with stations of the

aeronautical radionavigation service.


2700-2900 MHz Band Utilization2700-2900 MHz Band UtilizationNOAA NWS NEXRAD NetworkNOAA NWS NEXRAD Network


2700-2900 MHz Band Utilization2700-2900 MHz Band UtilizationFAA Radar NetworkFAA Radar Network


2700-2900 MHz Band Utilization2700-2900 MHz Band Utilization CurrentCurrent Radar and Potential Base Station DeploymentRadar and Potential Base Station Deployment

ASR Radar ASR Radar DeploymentDeployment

Meteorological RadarMeteorological RadarDeploymentDeployment

Typical Base StationTypical Base StationDeploymentDeployment


2700-2900 MHz Band Utilization2700-2900 MHz Band UtilizationRF SurveyRF Survey

Frequency Domain Representation of the 2700-2900 MHz Band within an Urban Environment (Los Angeles, California)


Meteorological RadarsMeteorological Radars

Base ProductsInterference CriteriaEffects of Interference Upon Radar

Performance


Meteorological Radar Base Meteorological Radar Base ProductsProducts

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


ASR and Meteorological ASR and Meteorological Radar Interference Protection Radar Interference Protection

CriteriaCriteria

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.


Effects of Interference on Effects of Interference on Radar PerformanceRadar 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


Example of Interference on Example of Interference on Radar OperationsRadar Operations

No Interference Interference


IMT SystemsIMT Systems

What is IMT ?


What is IMT?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


SimulationsSimulations

Study/Simulation ObjectivesSimulation CriteriaIMT Cell Topologies


Study/Simulation ObjectivesStudy/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.


Simulation CriteriaSimulation 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



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.



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.


Macro Cell TopologyMacro Cell Topology

75 km

75 km

SeparationDistance

Radar

Service Area

Radar is Offset from a Macro Cell Service Area


Micro Cell TopologyMicro Cell Topology

Separation Distance d

10 km

10 km

Radar

Service Area

Radar is offset from Micro Cell Service Area


Pico Cell TopologyPico Cell TopologyRadar is offset from Pico Cell Service Area

Separation Distance d

Radar

Service Area


Simulation ResultsSimulation Results

IMT to MeteorologicalMeteorological RadarsMeteorological and Airport Surveillance

Radars to IMT Systems Multiple MeteorologicalMeteorological and Airport

Surveillance Radars to IMT SystemsConclusions


Simulation Results Simulation Results IMT to Meteorological RadarsIMT to Meteorological Radars

I/N (dB) vs. Separation DistanceType G Meteorological Radar - IMT Micro Cell Base Station Cluster

-60

-40

-20

0

20

40

60

0 100 200 300 400 500 600 700 800

Separation Distance (km)

I/N

(dB

)

Micro I/N (dB) Macro I/N (dB) Pico I/N (dB)

I/N = -10 dB


Simulation Results Simulation Results IMT to Meteorological RadarsIMT 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.


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.

Simulation Results Simulation Results Meteorological and Meteorological and Airport Surveillance RadarsAirport Surveillance Radars to IMT Systems 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.

Simulation ResultsSimulation Results Meteorological and Meteorological and Airport Surveillance RadarsAirport Surveillance Radars to IMT Systems to IMT Systems


Simulation ResultsSimulation Results Meteorological and Meteorological and Airport Surveillance RadarsAirport Surveillance Radars to IMT Systems 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.


Simulation ResultsSimulation Results Multiple Meteorological and Multiple Meteorological and Airport Surveillance RadarsAirport Surveillance Radars to IMT Systems 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.


Potential IMT System Potential IMT System DegradationDegradation

Loss of serviceDropped callsDamage to sensitive receiver

electronicsPoor quality of serviceLimited deployment potential


ConclusionsConclusionsIMT to Meteorological and IMT to Meteorological and Airport Surveillance RadarsAirport 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 MeteorologicalMeteorological and Airport Surveillance Radars..


ConclusionsConclusionsMeteorological and Meteorological and Airport Surveillance RadarsAirport Surveillance Radars to IMT Systems 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.


ConclusionsConclusionsMeteorological and Meteorological and Airport Surveillance RadarsAirport Surveillance Radars to IMT Systems 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.


ConclusionsConclusions2700-2900 MHz Band Utilization2700-2900 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.


RecommendationRecommendation

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.


Thank You !Thank You !

National Weather Service 1 Results of Operational Compatibility Studies between ASR, Meteorological...

Documents

Transcript of National Weather Service 1 Results of Operational Compatibility Studies between ASR, Meteorological...