ATN/GNSS SeminarATN/GNSS SeminarVaradero, CubaVaradero, Cuba6 to 9 May 20026 to 9 May 2002

GNSS spectrum and signal vulnerability issues

Presentation 5.2 by

V. Iatsouk, GNSS Panel Secretary

ANB/ICAO

GNSS spectrum allocationsGNSS spectrum allocations

Current allocationsNew allocations to support system

enhancements and expansionCompatibility issues

FREQUENCY BAND FREQUENCY BAND 15591559 – 1610 MHz – 1610 MHz (ARNS/RNSS)(ARNS/RNSS)

GNSS F1 signals (GPS L1, GLONASS L1, GALILEO E1/2)

Total band 1559-1610 MHz is required for current and future GNSS

Sharing with other services will cause unacceptable degradation and restrictions on GNSS elements

Additional allocation to Fixed Service (some States in Europe, Middle East, Asia and Africa) continue to exist: On a primary basis until 2005 (or 2010) On a secondary basis until 2015

Frequency Band 960 – 1215 MHz Frequency Band 960 – 1215 MHz (ARNS, RNSS)(ARNS, RNSS)

RNSS allocation as of WRC-2000 GNSS F2 frequencies Sharing with DME on 1164 – 1215 MHz

frequencies Compatibility issues:

DME to be protected GNSS F2 signals to operate in DME environment Out-of-band (Radiolocation above 1 215 MHz)

interference

Frequency band 1215 – 1300 MHz Frequency band 1215 – 1300 MHz (Radiolocation, RNSS)(Radiolocation, RNSS)

No aeronautical allocation GPS L2, GLONASS L2, GALILEO E6 Used by SBAS reference receivers Compatibility issues

Radiolocation to be protected No protection for RNSS on a global basis

Frequency band 108 – 117.975 MHz Frequency band 108 – 117.975 MHz (ARNS)(ARNS)

GBAS VDL BroadcastSharing with VOR and ILSCompatibility issues:

VOR, ILS to be protected VDL Broadcast:

• To operate in VOR, ILS environment• Not to impose additional restrictions in adjacent

bands (FM Broadcast below 108 MHz, Aeronautical Mobile above 117.975 MHz)

GNSS vulnerability aspectsGNSS vulnerability aspects

GNSS signals’ vulnerability is generally recognized

Issues to be addressed: Interference cases and resulting threats

• Operational impact

• Mitigations

Interference casesInterference cases

Unintentional vs intentionalIn-band vs out-of-bandOn-board sourcesNatural phenomena

Intentional interferenceIntentional interference

Jamming Threat is valid Risks and impacts vary significantly Most mitigation options are suitable

Spoofing Extent of threat appears to be low Airborne collision avoidance, situation awareness and

separation assurance capabilities are potential mitigation aids

Other mitigation options are also suitable

Unintentional interference Unintentional interference

GNSS F1 signals in 1 559 – 1 610 MHz band Fixed service (not compatible) Mobile satellite communications (compatibility

standards exist)

GPS, GLONASS, GALILEO signals above 1 215 MHz RNSS/Radiolocation Service compatibility (studies

under way)

Unintentional interference (cont’d)Unintentional interference (cont’d)

GNSS GBAS in 108 – 117.975 MHz band VOR (compatibility criteria available) ILS (compatibility criteria being developed) Aeronautical VHF Communications

(compatibility criteria being developed) FM broadcast (compatibility criteria available) Envisaged VDL Mode 4, if allocated by

WRC-2003 (compatibility studies under way)

Unintentional interference (cont’d)Unintentional interference (cont’d)

GNSS F2 signals in 1 164 – 1 215 MHz band Designed to be compatible with ARNS Compatibility problems in DME high density areas

(core Europe, US, Japan)

On-board compatibility Compatibility standards exist Addressed through aircraft systems integration

Natural interference sourcesNatural interference sources

Ionospheric effects Storms Model anomalities Scintillations impacts

Other (heavy rainfalls?)

Operational ImpactsOperational Impacts

Effects of interference to be assessed taking account of: Traffic density Navigation infrastructure Surveillance system

MitigationsMitigations

Spectrum management, coordination and interference monitoring

Use of alternative navigation meansProcedural methodsContingency planning

Work towards WRC - 2003Work towards WRC - 2003

Promote cessation of fixed services in the 1559-1610 MHz band as early as possible

Finalize compatibility criteria and assessment methodology for RNSS in the 1164-1215 MHz band

Formalize GBAS operation in 108 – 117.975 MHz band

ConclusionsConclusions

• Global coverage and performance to support all phases of flight are dependent upon resolution of spectrum issues

• States to ensure freedom of RF interference when approving GNSS operations

• Interference threats to be assessed and mitigation strategy to be developed as a part of GNSS implementation planning