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17-19 Feb 2004Nairobi Aeronautical spectrum Seminar 1 ITU activities on interference ITU and related organization working groups involved Work accomplished.

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Presentation on theme: "17-19 Feb 2004Nairobi Aeronautical spectrum Seminar 1 ITU activities on interference ITU and related organization working groups involved Work accomplished."— Presentation transcript:

1 17-19 Feb 2004Nairobi Aeronautical spectrum Seminar 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 DGAC

2 17-19 Feb 2004Nairobi Aeronautical spectrum Seminar 2 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 17-19 Feb 2004Nairobi Aeronautical spectrum Seminar 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 17-19 Feb 2004Nairobi Aeronautical spectrum Seminar 4 ITU-R Rec. SM 1535 re safety services protection Recommends: 1.Appropriate spectrum management techniques 2.Increased consultation btwn all concerned services and operators (safety services and others, non- safety) 3.Use of interference mitigation techniques by other (non safety) services 4. Use of interference mitigation techniques by safety services 5.Use of Out of band limitations by other services 6.Safety analyses on a case by case basis : To achieve a required integrity level under all operational conditions

5 17-19 Feb 2004Nairobi Aeronautical spectrum Seminar 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

6 17-19 Feb 2004Nairobi Aeronautical spectrum Seminar 6 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 ( MHz) MSS is co-primary in the 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

7 17-19 Feb 2004Nairobi Aeronautical spectrum Seminar 7 Electronic news gathering/outside broadcasting sharing with the 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 17-19 Feb 2004Nairobi Aeronautical spectrum Seminar 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 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 MHz, and MSS, in 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

9 17-19 Feb 2004Nairobi Aeronautical spectrum Seminar 9 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 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 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 17-19 Feb 2004Nairobi Aeronautical spectrum Seminar 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 deals with RNSS protection in the band : extra margin of protection against factors like multipath ARNS: A prior Rec. IS.1009 recalls : ICAO adopted 8 dB safety margin for ILS =>to 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 defines a 5.6 dB margin for RNSS protection against non- aeronautical RFI

11 17-19 Feb 2004Nairobi Aeronautical spectrum Seminar 11 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

12 17-19 Feb 2004Nairobi Aeronautical spectrum Seminar 12 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

13 17-19 Feb 2004Nairobi Aeronautical spectrum Seminar 13 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 17-19 Feb 2004Nairobi Aeronautical spectrum Seminar 14 Compatibility study between FM broadcasting and aeronautical systems, GBAS and VDL Mode 4 WRC-03 permitted the use of the band by ARNS GBAS and aeronautical VDL Mode 4 It restricted the use of the band to the upper sub-band 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

15 17-19 Feb 2004Nairobi Aeronautical spectrum Seminar 15 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 , 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

16 17-19 Feb 2004Nairobi Aeronautical spectrum Seminar 16 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


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