Slide 1

An Approach for Interference Analysis

David FurlongRich Kelley Bill DanielsNESDIS spectrum managerAlion Science and Technology Alion Science and TechnologySilver Spring, MD 20910Suitland, MD 20746 Suitland, MD 20746David.furlong@noaa.gov richard.kelley@noaa.gov bill.daniels@noaa.gov01.301.713.2789 x 149 01.301.817.4636 01.301.817.4628Competition for spectrum has never been keenerWe share 18 bands1 with active services We own 21 exclusively passive bands2

For how long?

Commercial sector deploying increasing systems We will lose spectrum if we cant analyze sharing impacts and defend what we have

Now we have sophisticated tools to perform sharing analyses. We know how to use them.

Heres how, in a specific application

1ITU-R RECOMMENDATION ITU-R RS.515-4, Frequency bands and bandwidths used for satellite passive sensing2International radio regulations 5.340.BackgroundTechnique applied to a specific applicationSharing the 31.5-31.8 GHz band

fixed and mobile services and theEarthexploration-satellite service (passive)characteristics from fixed and earth exploration satellite services (FS and EESS)

(no known plans by mobile service)Assign characteristics to emitters and sensorScan a region of emitters with the sensorExamine the output for sensed emission valuesCompare results to existing interference standards Standards for satellite passive sensing are in ITU recommendations on performance and interference criteria 1, 2 .

1ITU-R RECOMMENDATION ITU-R RS.1028-2, Performance criteria for satellite passive remote sensing2ITU-R RECOMMENDATION ITU-R RS.1029-2, INTERFERENCE CRITERIA FOR SATELLITE PASSIVE REMOTE SENSING

TechniqueCharacteristics of emitters and sensorSensor characteristics are in an ITU recommendation 11ITU-R RECOMMENDATION ITU-R RS.1861 Typical technical and operational characteristics of Earth explorationsatellite service (passive) systems using allocations between 1.4 and 275 GHzConical and cross track sensorscross track U.S., Europe, Chinaconical Russian federation

AMSU-AATMSMTVZA-OKApproximate horizontal dimensions

Nadir FOV: 48.5kmNadir FOV: 74.8km30km 69km

Approximate area1856km24393km21625km2 Characteristics of emitters and sensorInstantaneous field of view (IFOV)Characteristics of emitters and sensoremitter characteristics are sometimes provided by the serviceCritical elements of characteristics:

Maximum emitter powerAntenna gainAntenna diameterAntenna typeAntenna patternRatio of antenna diameter over the wavelength (calculated)Respective antenna side-lobe gain from Rec.ITURF.1245-1 (calculated)e.i.r.p. (maximum)Channel spacingDeployment scenarioScan a region of emitters with the sensoremitters are placed every 500metres in areas of various horizontal extent

The smallest area, with 1,089 emitters Scan a region of emitters with the sensora passive scanner is orbited and periodically scans the area

Scan region of emitters with the sensor

Recommendation ITU-R RS.1029-2 -permissible interference levels use in sharing studies.

in this case the level is 164.24dBW/300 MHzCompare results to existing standardsCompare results to existing standardsATMS resultsrectangle widthRectangle areaNumber of emitters Power for each emitter(dBW)Total power from the rectanglePower density = total power divided by IFOV area(dBW/km2)16km256km2108945.5015.1339.2124km576km2240148.9115.1142.7132km1024km2422551.1214.9545.0640km1600km2656152.9714.8046.8448km2304km2940953.3513.6147.2456km3136km21278155.4614.39149.35Run simulations iteratively adjusting emitter poweruntil interference level is reached

AMSU-A and MTVZAOK are more sensitive than the ATMS.

The worst case sensitivity is for the AMSU for large areas (large number of emitters)In this case the power density is 51.97dBW/km2 Summary results for all simulations and sensorsAdjust 51.97dBW/km2 for polarization lossgaseous attenuationantenna side-lobe gainThe limit is 40.62dBW/km2 (for AMSU-A) Summary results for all simulations and sensorsa typical emitter would have 18dBW power

Means an emitter density of 0.0055 emitters/km2 Or a large city (3,139km2) there could be 17 emitters

If 2000 emitters are in the cities1 the deployment density is 0.154 emitters/km2.

To meet the interference threshold of -40.62 dBW/km2 each emitter could have only 32.5dBW of powerFixed service advertises -18 dBW/emitter

1ITU-R Working Party 5C REPLY LIAISON STATEMENT TO WORKING PARTY 7C INFORMATION REGARDING STUDIES UNDER QUESTION ITU-R 232-1/7

actual deployment advertised1 by Fixed ServiceResults and conclusiondeployment density provided by the fixed service would not be compatible with the sensor.

(compatible configurations would have an average of 17 or fewer emitters per city at typical power levels)

These results were presented during ITU-R meetings in September 201111 ITU-R SG-07 Draft new Report IUT-R RS.[31.5 GHZ SHARE] - Sharing the 31.5-31.8 GHz band by the fixed and mobile services and the Earth exploration -satellite service (passive)