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International Civil Aviation Organization
WORKING PAPER / ACP-WGF15/ WP-30 Rev1
7 June 2006

AERONAUTICAL COMMUNICATIONS PANEL (ACP)

FIFTEENTH MEETING OF WORKING GROUP F

Cairo, Egypt7-13June 2006

Agenda Item 4: / MLS interference protection and WRC’07 preparation

DRAFT PRELIMINARY MLS INTERFERENCE SUSCEPTIBILTY TEST PLAN

1.Introduction :

1.1. Recent NSP/SSG (Brussells, 8-11 June 2006) actions:

Examination of NSP papers WP 6 and 27 and Flimsy 1 have given rise to the following actions in relation to issues raised about the Annex 10 MLS SARPS- defined protection levels of -100dBm (or -94.5 dBW/m2 power density ) against intra-MLS / adjacent channel emissions and -130 dBm against external sources of interference:

a)Action Item SSG9/14: SSG to investigate the basis for the derivation of the interference limit value of 94.5 dBW/m2 as applicable to MLS-type interference (see *1)

b)Action Item SSG9/13: US to explain, why noise was not taken into account for the derivation of the values in the table in Appendix C of WP6(see *2)

c)Action Item SSG9/12: SSG to investigate the basis for the derivation of the interference threshold value of 130 dBm for noise-like interference(see *3)

d)Action item SSG9/1: UK to provide to SSG members a soft-copy of the ITU document “4A temp 84” from 1996, Meeting of ITU WP 4A, Rio de Janeiro, 1996, containing background information of the derivation of the –130 dBm interference threshold for the protection of MLS against undue emissions from other systems(see *3)

e)Action Item SSG9/15: France to undertake measurements to investigate the impact of noise-like signals (AMT, FSS, RNSS) on the performance of MLS receiver. A test plan for the measurements shall be circulated among SSG members before undertaking the measurements
note 1 : this is equivalent to -100 dBm at MLS airborne antenna
note 2: (extracted from meeting report):In the first part of (NSP/SSG)WP27 the issue was raised, whether the Signal-To-Noise ratio used in the recently updated GM has to be interpreted as a pure “Signal-To-Noise ratio”, or as a “Signal-To-(Noise-plus-Interference)-Ratio”….One member of the SSG volunteered to provide further background material to the next SSG meeting
note 3: The SSG, , agreed that, until additional evidence is made available to justify its revision, the interference threshold value of 130 dBm in 150 KHz, corresponding to -124.5 dBW/m2 is an aggregated interference limit for all possible external interference sources. Members from one state expressed their reservation to the value and would like to keep the possibility at future SSG meetings to review the value, providing new evidence is provided to the SSG prior to WRC2007. Their concerns is on the applicability of this value for noise-like type of interference like RNSS, FSS, AMT, AM(R)S, AMS(R)S

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2.Tests to be performed:

Test nr / Desired MLS signal (D) / Interference type / Comments/notes
1 / Yes, at min. level / AMT(aeronautical mobile telemetry)and/or noise-like / Vary D vs AMT in level and frequency offset from co-channel to out-of-band cases. Also to take care of RNSS and FSS like interference
2 / Yes, at min. level / MLS-type (adj. ch.) / At SARPS-defined 840 KHz away + vary freq. offset
3 / None / MLS-Type (adj. ch) / At 840 KHz, to check MLS data decode integrity
4 / None / AMT or noise-like / Co-ch. and OOB cases to check MLS data decode. integrity
5 / Yes, min. level / 802.16 type / To assess MLS vs Airport AM(R)S protection/sharing
6 / None / 802.16 type / to check MLS data decode integrity
7 / None / None / to assess MLS noise floor

3.Procedure :

Based on EUROCAE ED 36B (to be released shortly) . Pass/fail criteria are defined using PFE, CMN measurement/limit and error-flag detection

4.Schedule /main milestones:

  1. Present draft preliminary test plan to WGF15 in June 06,
  2. Electronically circulate Plan to NSP membership by end of June,
  3. Elaborate test procedure in details by July 15th.,
  4. Elaborate the test procedure in details by beginning of August.
  5. Validate the test procedure by NSP members by correspondence in August,
  6. Present validated test plan and final procedurewith NSP membership comments to ITU-8B in September (specifically the part on non-MLS interference protection)
  7. Present test results to next NSP/SSG meeting in Oct. (or Nov. ?) for validation
  8. Present validated test plan and final test data to CPM in Spring 2007
  9. Finalize the new ITU-R recommendation on the MLS protection at the last 8B meeting in June 2007

5.On-going actions in preparation for test campaign:

  • Bench test equipment gathering : AMT signal simulator, MLS signal generator, 5GHz input coupler, 802.16/Airport AM(R)S signal generator
  • Test Cost estimation and facility selection : French DGAC/DSNA/DTI or Airbus in Toulouse, France
  • Test campaign preparation and kick-off scheduled at major DGAC/Airbus meeting on 22 June

6.Conclusion:

FMG 15 Members are kindly invited to note the preliminary test plan and provide comments as appropriate.