ITU activities on interference

1
ITU activities on interference

• ITU and related organization working groups
  involved
• Work accomplished in the form of ITU-R
  recommendations dealing with the protection of
  aeronautical services
• On-going work
• Ultra Wide Band Systems (UWB) potential threats
• WRC-03 initiated study on FM broadcasting and
  GBAS and VDL M4 compatibility
• ITU-R 8B initiated feasibility study on the use
  of statistical and operational aspects related
  to radar protection criteria
• Presented by Alain DELRIEU, French
  DGACalain.delrieu_at_aviation-civile.gouv.fr

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WORKING GROUPS INVOLVED on INTERFERENCE THREATS
TO AVIATION SYTEMS and PREVENTION

• Mainly
• ITU-R 8B Maritime, GMDSS, Aeronautical Mobile
  Service and radiodetermination (radiolocation
  radionav.) service
• ITU-R 8D All mobile services and
  radiodetermination satellite services
• But also
• ITU-R 8F IMT-2000 and beyond
• ITU-R 4B Fixed satellite service and
  performances, satellite news gathering
• CEPT , e.g. SE and FM groups
• Study work-items usually result in
  Recommendations , approved by Radio Assemblies
• Usually initiated by WRCs , but also directly
  triggered by ITU-R study groups

3
ACCOMPLISHED work ITU-R Rec. SM 1535

• Object The protection of safety services from
  unwanted emissions
• Recognizing Safety services need special
  attention
• States are obligated under R.R. 4.10, to take
  measures to insure freedom of harmful
  interference
• Protect the reception of weak signals against
  out-of-band and spurious emissions from other
  systems
• Need to Complement general R.R emission limits
  by standards or applicable ITU-R Recommendations
• Relevant to Aviation are ITU-R M.441, 960,1234,
  1317,1318,1463,1464,1342 S.1342 and SM 1009

4
ITU-R Rec. SM 1535 re safety services protection

• Recommends
• Appropriate spectrum management techniques
• Increased consultation btwn all concerned
  services and operators (safety services and
  others, non-safety)
• Use of interference mitigation techniques by
  other (non safety) services
• Use of interference mitigation techniques by
  safety services
• Use of Out of band limitations by other services
• Safety analyses on a case by case basis
• To achieve a required integrity level under all
  operational conditions

5
ITU-R Rec. SM 1535 re safety services
protection (contd)

• General safety criteria for the protection of
  aeronautical services
• Need for quantitative harmful interference
  threshold specific to ea. system based on
  appropriate safety criteria
• Technical planning criteria to provide
  interference protection
• Usually available within aviation to prevent
  interference between aeronautical systems, but,
• Generally absent for non-aviation services and
  systems
• Consequently ea. potential non-aeronautical
  interfering system needs individual attention
• Well known sources of man-made emissions and
  interference include
• LF/MF AM broadcasting
• Video-cable distribution system
• Industrial, scientific and medical equipment
• Power(utility) line distribution

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5 GHZ band sharing between ARNS/MLS and FSS
feeder links to for non GSO

• Rec. ITU-R S.1342 set coordination trigger
  distance for MLS vs FSS/feederlink, in the 5 Ghz
  band (5091-5150 MHz)
• MSS is co-primary in the 5091-5150 Mhz since
  WRC-95
• distance trigger for mandatory coordination is
  243 NM (450 km) or less
• Also MLS range triggers for o-o-b and in-band
  interference susceptibility, Roob and Rin
• Consider mitigation factors
• look for site-specific blocking and FSS
  filtering

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Electronic news gathering/outside broadcasting
sharing with the 2.7-2.9 GHz ARNS Radar band

• CEPT/ECC developed an ad-hoc Recommendation,
  which is not yet at ITU-R level
• Background ENG/OB in Europe has been forced out
  of bands now allocated to land mobile services
  (IMT-2000) and is being digitized
• Two potentially interfering mechanisms
• Overloadd Rcvrs front-end causing
  saturation/gain loss
• Generated 3rd order intermod products falling
  within radar IF band
• Work study reported in CEPT/ECC Report 006 and
  ECC REC (02)09, allowing band-sharing on
  conditions
• Nationally, with exclusion zones, 10 Km
  radar-centered
• Required coordination in case ENG/OB exceeds a
  specific threshold of 2dBµV/m, within or at a
  country borders
• Note in co-channel case, the threshold trigger
  distance exceeds radio-horizon
• Only a few European countries are proposing this
  band sharing

8
Feasibility study of MSS terminal sharing with
GPS/L1 and GLONASS

• WRC-97 considered an MSS co-primary allocation
• To Mobile Satellite Service (INMARSAT-proposed
  Horizon)
• With RNSS in the band 1559-1567 MHZ
• That conference adopted Res 220 to study
• Technical criteria
• Operational and safety requirements
• in order to determine if sharing btwn RNSS,
  GPS/L1 and GLONASS , in 1559-1610 MHz, and MSS ,
  in 1559-1567 was feasible
• WRC-2000, on the basis of a.m. study concluded
• The required PFD level to protect RNSS cannot be
  met by the proposed MSS system terminals
• Conclusion sharing not possible to protect
  present and future GNSS

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RNSS/GNSS and ARNS/DME Band sharing decided at
WRC-03

• WRC-2000 introduced a co-primary allocation to
  RNSS
• In the DME sub-band 1164-1215 MHz
• With a provisional PFD limit -115 dBW/m2 in any
  1 Mhz
• Invited ITU-R , under Res 605 to study, for
  WRC-03
• appropriate technical, operational and regulatory
  matters
• to confirm compatibility btwn RNSS and ARNS(DME)
• Including the determination of an aggregate PFD
  limit
• WRC-03 endorsed ITU-R studies done since WRC-00,
  in particular
• The principle and value of an aggregate (several
  RNSSs) equivalent PFD at -121.5 dBW/m2/MHz
• Radio-Comm. Assembly-03 approved Rec M.1642,
  giving
• Methodology to assess max aggregate ePFD for all
  contemplated RNSS systems (GPS/L5 GALILEO 3
  others)

10
LINK MARGIN FOR SAFETY OF LIFE SERVICES

• Need to set aside adequate transmission link
  margin has long been recognized within ITU
• For radio navigation service, typically 6 to 10
  dBs
• Critical for SOL applications to mitigate RF
  interference easily not quantifiable but real
• Rec M. 1318 deals with RNSS protection in the
  band 1559-1610
• extra margin of protection against factors
  like multipath
• ARNS A prior Rec. IS .1009 recalls
• ICAO adopted 8 dB safety margin for ILS
• gtto verify system performance with RFI and ILS
  carrier reduced by safety margin
• RNSS/GNSS uses wideband modulation, ARNS/ILS and
  MLS narrowband
• Critical factor is C/N and the Satellite carrier
  is relatively fixed contrary to LIS and MLS
• If RFI is reduced by 6 dB , the C/N is up by
  only 2.5 dB vs 6dB for ILS MLS
• Rec M. 1343 defines a 5.6 dB margin for RNSS
  protection against non-aeronautical RFI

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CONSIDERATIONS ON SAFETY MARGIN SIZING REC
ITU-R M.1477

• Allowable aggregate RFI from non-aeronautical
• must be significantly below the design
  interference theshold
• 6 DB value for aeronautical services is in line
  with other safety services
• Needed to account for all aeronautical design
  uncertainties
• -140 dB(W/MHz) design threshold for SBAS
  Receiver for CAT I precision approaches
• Hence a Threshold of -146 dB(W/MHz) for all
  non-aeronautical aggregate interference
• Note a GNSS RCVR in acquisition mode it is 6 dB
  less immune
• Additionnal margins may be required, depending
  on
• Operational requirements including accuracy,
  availability of service, continuity and integrity
• Configuration of RNSS including augmentations
• Future source of RFI

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INTERFERENCE RISK ALLOCATION AND SAFETY COMPLIANCE

• Interference allocation the methodology
  employed for communication networks design is
  not acceptable as based on service
  unavailability (in the few range)
• Aeronautical systems must be designed to handle
  very rare events ,of the order of 1x10-6 / hour
• Any ARNS/RNSS proposal must include failure modes
  analysis
• And must address how to maintain overall safety
  performance despite ageing

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The UWB challenge compatibility with existing
radiocommunication services

• Ultra Wideband System
• Transmist low power radio signal with
• Very short duration (order of few ns even less)
• ITU groups involved in the UWB studies
• Question ITU-R 226/1 Spectrum management
  framework related to the introduction of
  ultra-wideband devices
• - Question ITU-R 227/1 Compatibility between
  ultra-wideband devices and radiocommunication
  services
• 4 Working groups have been set-up
• WG 1 collects and documents key features,
• - WG 2 is addressees UWB compatibility issues
• - WG 3 prepares a spectrum management framework
  as guidance to Administrations
• - WG 4 develops appropriate measurement
  techniques for UWB emissions

14
Compatibility study between FM broadcasting and
aeronautical systems, GBAS and VDL Mode 4

• WRC-03 permitted the use of the band 108-117.975
  by ARNS GBAS and aeronautical VDL Mode 4
• It restricted the use of the band to the upper
  sub-band 112-118 Mhe
• The opening of the lower sub-band is dependant
  upon study results
• Compatibility of a.m. systems with FM
  broadcasting, analog and digital format

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NEW STUDY ITEM Feasibility of using statistical
and operational aspects to define radar
protection criteria

• At its November 2003 meeting ITU-R Working Party
  8 B discussed the feasability of the use of
  statistical and operational aspects in the
  protection criteria for radio-determination radar
  systems.
• During the ITU-R study period 2000-2003, WP 8B
  conducted several studies related to the
  compatibility between radio-determination radar
  systems and other services/systems
• The objective of this work programme is to
  identify protection criteria for radar systems
  taking into account statistical and operational
  aspects of radar systems and other relevant
  parameters

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CONCLUSIONS

• The Aviation community benefits from ITU-R work
  aiming at establishing protection criteria for
  safety-related services
• And should participate fully to the work of ITU
  groups
• By bringing in real operational experience
• A value of 6 dB margin of safety is the minimum
  widely accepted within ITU-R and ICAO fora.
• The study-item on feasibility of a statistical
  approach to set radar protection ratios should
  receive full attention and participation from
  ICAO members