7/24/2008

AWS-2 and AWS-3 Interference

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7/24/2008

Summary

• FNPRM Band Plan

• AWS-2 H Block Interference– To MSS Satellite Receivers– To ATC Base Stations

• AWS-3 TDD Interference– Mobile to Mobile Interference to Satellite Devices– MSS/ATC Device Receiver Overload – OOBE Interference to MSS/ATC Devices

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ICO

• Four interference boundaries:

• Boundaries 2 and 4 impact ICO’s MSS/ATC system

7/24/2008

FNPRM Band Plan

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ICO

1 2

Original

J Block

~o 0 0 01'- 00 Q 0~ ~ ~ NN N N N

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UPCS

7/24/2008

Boundary 4: H Block Interference to MSS Satellite Receivers (1 of 2)

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• H Block base station transmit would be directly adjacent to MSS/ATC receive

• H Block in-band power will cause severe receiver noise rise at the satellite– ICO G1 has been successfully launched – no modifications are possible– ICO’s satellite must cover the entire 20 MHz MSS allocation– Receiver filters will not be able to reject energy from base station transmissions in the

upper 1.5 MHz of the H Block– This H Block interference will raise noise levels on the satellite feeder link– To avoid saturation, the feeder power amplifier will reduce gain, reducing satellite

return link performance by several dB (impact worsens as more H Block base stations are deployed) thus greatly impacting mobile satellite communications

• To protect MSS operations, the H Block base stations must not transmit in 1999-2000 MHz - this must be established as guard band

• To control interference received by the satellite, aggregate base station EIRP for 1995-1999 MHz must not exceed 32 dBW per sector

ICO

7/24/2008

Boundary 4: H Block Interference to MSS Satellite Receivers (2 of 2)

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• Interference PFD arriving at the satellite for different base station power levels was simulated for a nationwide H Block deployment:

• The FNPRM would allow a high power flux density at the satellite, with the upper 1 MHz not attenuated by filtering and arriving in-band to the receiver

• The ICO proposal would provide a 7 dB lower PFD and, more importantly, move the interference lower in frequency such that the receiver filter may provide 10+ dB of attenuation

• Alternatively, using the H Block for mobile transmit would better protect the satellite receiver:

• H Block mobile allocation would generate 24 dB less interference to the satellite than the FNPRM recommendation

ICO

H Block FNPRM Transmit Analysis: 32 d BWIMHzSector EIRP (main beam): 32 dBW/MHz

Antenna gain reduction in satelite elevation: -20 dBSector EIRP (satellite elevation angle): 12 dBW/MHz

# sectorslsite toward satellite: 1Sector EIRP in 5 MHz to sat: 19 dBW/5MHz

Total sites nationwide: 20,000Spreading loss: 162.91 dB

Clutter loss: o dBPower- flux: density at satellite antenna: -100.9 dBW/m2

H Block Base Station Transmit Analysis: 32 dBWsector"Sector E1RP (main beam): 32 dBW/secla

Antenna gain reduction in satellite elevation: -20 dBSector EIRP (satellite elevation angle): 12 dBW/secla

# sectorslsite toward satelite: 1Sector EIRP in 5 MHz to sat: 12 dBW/5MHz

Total sites nationwide: 20,000Spreading loss: 162.91 dB

Clutter loss: o dBPower- flux: density at satEllite antenna: -107.9 dBWhn2

H Block Mobile Transmit AnalysisDevice transmit power maximum: 0.2 W

Average level of Tx power control: -10 dBAverage device EIRP: -17 dBW

# of nationwide subscribers: 20,000,000% of subscribers transmitting simultaneously: 15%

Spreading loss: 162.91 dBClutter loss: 10 dB

Power flux density at satellite antenna: -125.1 dBWhn2

7/24/2008

Boundary 4: H Block Interference to ATC Base Stations (1 of 2)

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• The FNPRM proposal of 43 + 10 log P for the H Block would rely on commercial negotiations to resolve the H Block and MSS/ATC base-base and mobile-mobile interference boundary at 2000 MHz

• This approach is highly inequitable to MSS/ATC – coordination works when services are similar, such as neighboring terrestrial systems, but does not work when one system is disadvantaged, such as a satellite system

– Satellite communication requires an optimal link budget– All MSS/ATC devices must work on the satellite – Device transmit filter performance is already maximized to meet the existing 43 + 10 log P

requirement at 2000 MHz and still close the loop with the satellite– More stringent device filtering will severely harm satellite communications

• ICO requests protection similar to the EBS/BRS rules to protect from base-to-base interference:

– BTS-BTS separation distances greater than 1.5 km: OOBE of 70 + 10 log P at 3 MHz from the channel edge

– BTS-BTS separation less than 1.5 km: OOBE of 70 + 10 log P – 20 log (Dkm/1.5) at 3 MHz from the channel edge

– When co-located, limit the undesired signal level at the ATC base station receiver to no more than -114 dBm/MHz

ICO

7/24/2008

Boundary 4: H Block Interference to ATC Base Stations (2 of 2)

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• The calculations supporting ICO’s request for H Block BTS emissions limits are provided below, for an ATC UMTS base station:

• To achieve the additional 28 dB of isolation, the emissions limit must be 70 + 10 log P at 1.5 km base-base separation.

ICO

Thermal noise: -174 dBmlHz a=10~(1.38*1()A-23}+10~(290}+30

Noise bandwidth: 3.84 MHz b=UMTS carrier bandwidth

Noise power: -108 dBmI3.84 MHz c=a+1(Mog(b*1000)ATCBlS

Receiver noise figure: 5.0 dB dReceiver

Receiver noise floor: -103.1 dBm e=c+d

Interference degradation limit 1 dB f=acceptable BTS noise rise

Max interfering signal at receiver: -109.0 dBmI3.84 MHz g=(e+f>m - emOOBE of 43 + 10 log P: -13 dBmIMHz h=FNPRM prq>osaI

H Block BTS cable loss: 3dB i

H BlockBlS H Block BTS antenna gain: 17 dBi j

Interferer ATC BTS antenna gain: 17 dBi k

ATC BTS cable loss: 3dB IH Block interference at ATC receiver: 15 dBm m=h-i+j+k-l

IsolationRequired Over-air Isolation: 129.8 dBlMHz n=m-g+1(Mog(3.84)

CalculationsMinimum separation Distance: 37 km o (using Free Space Path Loss)

Isolation for 1.5 km Separation: 28 dB P (using FSPL)

OOBE Limit at 1.5 km separation: 70.8 dBlMHz q=43+p

7/24/2008

H Block Summary

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• A combination of guard band, power limits, and out-of-band emissions limits must be implemented to avoid interference to satellite and ATC base station receivers.

• Satellite Protection:– 1 MHz guard band from 1999-2000 MHz– Aggregate BTS EIRP per sector limit of 32 dBW for 1995-1999 MHz

• ATC Base Station Protection:– OOBE Limits:

BTS-BTS separation distances >1.5 km: OOBE of 70 + 10 log P at 3 MHz from the channel edgeBTS-BTS separation <1.5 km: OOBE of 70 + 10 log P – 20 log (Dkm/1.5) at 3 MHz from the channel edgeWhen co-located, limit the undesired signal level at the ATC base station receiver to no more than -114 dBm/MHz

ICO

7/24/2008 9

AWS-3 TDD Interference

ICO

7/24/2008

Boundary 2: Mobile to Mobile Interference to Satellite Devices

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Typical RF front end of PCS/cellular mobile (receive):

Typical RF front end of Satellite mobile (receive):

• As shown below, the receive chain in the RF front end of a satellite device is inherently more sensitive than the RF front end of a traditional PCS or cellular mobile

• The LNA in the satellite front end has higher gain than a typical PCS LNA, and is cascaded with a second LNA to minimize noise figure and close the link to the satellite; however, this design also reduces receiver blocking performance, making satellite devices more susceptible to adjacent channel interference

• Filter design imposes similar constraints given the imperative of low insertion loss for satellite coverage

• Thus mobile-to-mobile interference will be more severe when satellite mobiles are the victim than when PCS-like mobiles are the victim

ICO

7/24/2008

Boundary 2: AWS-3 TDD Will Cause Receiver Overload

• ICO mobiles require guard band to avoid receiver overload from TDD handsets – ICO stated its support for TDD when J Block provided frequency separation, and assuming proper

service rules for AWS-3 and ICO equipment design modifications– Extending TDD operations to 2180 MHz will cause receiver overload to MSS/ATC mobiles, especially

given the sensitive device front end receiver– ICO current device design does not account for TDD operation in AWS-3, but preliminary evaluation

indicates a receiver blocking level of -56 dBm is possible (in 2170-2180 MHz region)– Combined with the isolation provided by 3 meters of minimum separation, MSS/ATC devices require

10 MHz guard band from AWS-3 TDD transmission

• MSS/ATC customers will rely on satellite coverage throughout the United States • Satellite communication operates near the receiver sensitivity constantly given the long

distance to the geosynchronous satellite• Without protection, MSS/ATC devices will be subject to interference throughout the country, a

much more widespread problem than that posed to cellular, PCS or AWS-111

ICO

AWS-3 Device Tx Level: 23 dBm a: From FNPRM

MSS/ATC Receiver Blocking Level: -56 dBm b: level at 2170 M-1z

Isolation Required: 79 v=a-b

Isolation from 3 m Separation: 49 dB d: from FSPL formula

Additional Losses: 9 dB e

Filtering Attenuation Required: 21 dB f=c-d-e

Minimum Guard Band: 10 MHz g: from filter ralloff

7/24/2008

Boundary 2: AWS-3 TDD OOBE Will Cause Receiver Noise Rise

• AWS-3 TDD out-of-band emissions must also be controlled– The AWS-3 TDD device must contain sufficient filtering to control emissions into the MSS/ATC

device receive band, given the sensitive device receiver – One service supported by MSS/ATC is GMR two-way communications via the satellite– OOBE calculation for GMR is shown below:

OOBE Calculation for ICO GMR Service

– For a 3 meter separation between devices, the maximum signal level permissible at the antenna of the AWS-3 device is -60 dBm/MHz at 2180 MHz

• This translates to a required OOBE limit of 90 + 10 log P with a 1 MHz measurement bandwidth

• The FNPRM proposal of 60 + 10 log P is insufficient, corresponding to an interference radius of 100 meters, greatly impacting MSS/ATC device performance

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ICO

Thermal noise: -174 dBmlHz a=10~(1.38*10A-23)+10~(290)+30

Noise bandwidth: 156.25 kHz b=GMR carrier bandwidthNoise power: -122.0 dBm/15625 kHz c=a+1<Mog(b*1(00)

Receiver noise figure: 1.9 dB dReceiver noise floor: -120.1 dBm e=c+d

Interference degradation limit: 1 dB f=acceptable noise riseMaximum interfering signal: -126.0 dBm Ig=(e+f)lin - e lin

Isolation from 3 m separation: 49 dB h=free space path loss in 3 m

Additional losses: 9dB iOOBE Power at 2180 MHz: -59.9 dBmlMHz li=g+h+i+10"1og(1000/156.25)

7/24/2008

AWS-3 Summary

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• Designating the 2155-2175 MHz AWS-3 block as flexible use must be accompanied by regulatory requirements to protect adjacent MSS user terminals:

– Mandatory guard band from 2170-2180 MHz (downlink only operation)– Device EIRP limit of 200 mW below 2170 MHz– Device OOBE must not exceed 90 + 10 Log P at 2180 MHz, with 1 MHz

measurement bandwidth

• AWS-3 expansion to 2180 MHz must not occur given the significant uncontrolled interference to MSS/ATC devices that would result.

ICO