AERONAUTICAL COMMUNICATIONS PANEL (ACP)
WORKING GROUP M
SIXTH MEETING OF THE IRIDIUM SUB-GROUP
Montreal, Canada 24-26 October, 2006
REPORT (DRAFT)
1.General
1.1The sixth meeting of the Iridium Sub-Group of the ACP Working Group M was held 24-26 October, 2006 at ICAO Headquarters. The meeting was chaired by RobertKerczewski, NASA Representative nominated to chair by the United States.
1.2The meeting was attended by: Robert Kerczewski (NASA); Torsten Jacob (ICAO); Robert Witzen (ICAO); Mike Meza (Iridium); Kelly O’Keefe (for Iridium); Brandon Hinton (Iridium – NextGen Communications); Don Jansky (for Iridium); Brent Phillips (FAA);
1.3The agenda for the meeting was reviewed and approved.
2.The REPORT From the fifth Iridium Sub-Working Group meeting.
2.1The report was approved without comment.
2.2The status of action items from the Fifth Iridium Meeting, as recorded in the meeting report, was reviewed.
2.3Iridium Manual and Validation Report Actions:
2.3.18.1.1 - Mr. Kerczewski and Mr. LaBerge had submitted materials regarding Iridium availability for the current meeting.
2.3.28.1.2 – Mr. Fistas provided the SNSDU information from the ISO 8348 document and it has been posted as an Information Paper to meeting #6.
2.3.38.1.3 – Open Action – Mr. Jacob had not heard back from Inmarsat, and a new contact person was recommended – Alan Shuster Bruce as per C. LaBerge. However, as per Mr. Jacob, it may be too late for any changes to the SARP language with respect to subsystem vs. end-to-end performance numbers.
2.3.48.1.4 – Mr. Nikos Fistas sent an e-mail providing information regarding provider-invoked release/provider-invoked reset.
2.3.58.1.5 – M. Meza attended Sub-group N1 meeting. This is an issue for 5+ years out; not the near term. Investigating IP solution for ATN – may fit within our future satellites and what we are looking at for technology. Leaving ATN wording is safe. Terry Davis (Boeing) is interested in work being undertaken at Iridium and meetings are planned. Not too much more in that working group of interest, but the group will continue to monitor IP.v6 developments.
2.4AMS(R)S Draft SARPs Items
2.4.1The section 4.2.1.1 recommendation was removed.
2.4.2The apparent redundancy of Sections 4.6.4.1.1 and 4.7.2.1. The secretariat proposed no change because 4.7 is provisions for packet data service interface, 4.6.4 performance characteristics for packet data services including delay parameters and integrity parameters. Mr. Jacob further noted that there is agreement on the need for some further work on these SARPS in ACP.
2.4.3The Secretary will consider proposing to the ANC further work in the area of the Inmarsat-requested minimum values for the SARPs requirements and the implications of the facts that these requirements are inadequate for most airspace domains and satellite systems can now well exceed these requirements. The Secretary will propose that ACP keeps working on performance based SARPS for specific uses, domains.
2.4.4Regarding the US comment on SARPs Section 4.6.5.1.3 that there might be a problem using Voice over IP, Mr. Phillips was unable to get further clarification. Mr. Jacob believes this item should be watched for possible future work in the ACP.
2.4.5Regarding sections 4.6.4.1.3.3 and 4.6.4.1.3.4, Mr. Fistas did not yet obtain further clarification from Inmarsat.
3.Review of AMS(R)S SARPS Status
3.1Mr. Jacob noted that the process of integrating comments was ended on 23 October. The SARPs is undergoing an internal review process before being brought to the Aeronautical Navigation Council (ANC). The ANC will review the SARPs in November and no major difficulties are expected.
3.2Mr. Jacob noted that a new definition – Connection Resilience – was added to the SARPs (4.6.4.1.3.3) basically regarding dropped calls. Definition is from the ISO-8348 and should be incorporated into the reports.
3.3Further clarification on the SARPS and SNSDU definition from Mr. Jacob: the standard, SARPs 4.6.4.1.2.2 section relates that ino measuring delay figures, SNSDU of 128 octets needs to be used – but this does not define SNSDU length to be only 128 octets.
4.REVIEW OF the iridium validation report
4.1Mr. Meza displayed autodialer test setup diagrams examples.It was agreed that such diagrams would bb useful in the validation report.
4.2Regarding WP 599 will be added as an annex to the report.
4.3Section 2.1 – Mr. Hinton will check new table measurement criteria in DO-294 and update Annex A, Table 1, Ref J calculations as needed.
4.4Section 2.2 – priority and preemptive access. Integrate appropriate text of WP-598, Priority, Precedence and Preemption for AMS(R)S in the Iridium System, to describe these aspects of the Iridium system and possible testing scenarios. Testing results are not required for completion of the report as long as a description of the planned tests is included. WP-598 was added as an Information Paper to Meeting #6 and was proposed to be added as an annex. Questions were also raised about the priority level of 911 calls. Section 2.2.1 of WP-598 to be consulted. Prioritization should be considered for both voice and data. Mr. Meza noted that the priority and preemptive access will be difficult to verify by measurement and inquired whether any testbeds might exist that could provide such testing.Mr. Philips agreed to check with the FAATechnicalCenter to see if they have an ATN testing process and report feedback to M. Meza. It is likely that analysis will be the only viable validation method.
4.4.12.2.1; 2.2.2 – Priority and Pre-emptive Access – Identification of Priority/Voice Priority over Data: The new SARPs language will be added. This section will be addressed based on the new SARP language and contents of WP-598.
4.4.2Section 2.4.2.1 - Failure Notification. 2.4.2.1 – Performance Requirements – Failure Notification, Timely Notification on time, location and duration of outages. New text already added, but more information is required about planned or announced outages. Additional testing data from already recorded and observed times will be included in this section. An information paper will be added describing this process and referenced in the report with a very high-level, one or two paragraph summary focused on actual validation – software, ephemeris data (from ITU document), etc.
4.4.3Section 2.4.2.2 - Failure Notification within 30 seconds. It was noted that the phrase “of the time when it detects such a loss” might be removed based on potential SARPs change. Mr. Jacob will notify Mr. Meza of possible changes, and any required clarifications completed. Mr. Meza will also include explanation of tests and observed times of when fault conditions started and when they were detected and reported.
4.4.4Section 2.4.3 - AES requirements. Mr. Hinton notes that Iridium can perform to 8 degrees elevation, dependent on antenna placement.An analysis based on measured results to show meeting the requirement for all operational locations, need to state the assumption of proper antenna placement.
4.4.5Section 2.4.4 - Packet Data service Performance. Some text changes already made, however, Mr. Jacob will consider what additional information ICAO specifically requires for validation. M. Meza to review Annex 10, Attachment A, Section 7.2, satellite sub-network (packet data performance).
4.4.6Sections 2.4.4.5; 2.4.4.6; 2.4.4.7 – on Packet Data Performance. Mr. Meza to add descriptions and diagrams of the auto-dialer configurations either in the respective sections of the report or as an annex.
4.4.7Section 2.4.5.1 and 2.4.5.2 - Packet Data Service Performance – Integrity Residual Error Rate, from aircraft/to aircraft. Additional data may be required for SBD (RUDICS already included). Data has been collected already and will be considered for addition to the Validation Report.
4.4.8Section 2.4.5.3 - Packet Data Service Performance – Integrity, Connection Resilience. Need to add language regarding calls dropped by the network through no specific fault of either side.Note again that an additional definition of connection resilience will be added to the SARPs.
4.4.92.4.6.1.1 - Voice Service Performance – Call processing delay, AES Origination. Additional data is being collected and will be integrated into this section, including the sub-network only. It was noted that the measurements show removing the connection through the PSTN reduces the delay to16 seconds. The 95th percentile delay is expected to be 20 seconds.
4.4.10Section 2.4.6.3 - Voice Service Performance – Voice Capacity. Mr. Meza will consult with ITT on how they assessed this data. Mr. Jacob proposed that the measurement can be simple and straightforward arranged perhaps measured through limits of aircraft per beam – arranged regionally.
4.4.11Sections 2.4.7.1/2.4.7.2/2.4.7.3 – Security Sections. The text was amended as discussed to note the availability of additional security measures through application layer encryption, and through aviation network service provider (i.e. ARINC and SITA).Mr. Jacob has requested that reference be added to a specific document of the GSM standard in the Validation Report, but not the Technical Manual.
4.4.12Section 2.5.1 2 – System Interfaces – ICAO 24 bit aircraft address. Mr. Jacob noted that the mapping of the SIM card to the ICAO 24-biut address is performed by the service provider external to the Iridium subnetwork and the section was adjusted and the last paragraph deleted.
4.4.13Section 2.5.2.1 – System Interfaces: Packet data service interfaces, ATN interface. Language from section 8.5 of the Implementation Manual to be added to these sections of the Validation Report. It notes that the interface has not yet been defined by ICAO, but when it is Iridium will work with service providers to meet the requirement.
5.REview of the IRIDIUM Manual
5.1Iridium Availability Analyses. Mr. LaBerge presented his availability analysis. Based on working paper 573. This presentation deals with an update of that information, he’s not sure that it was actually presented but the update was made. Key items:
5.1.1Note it does not take into account satellite replenishment time of 10 days.
5.1.2Quick review of ITT presentation from last time – Chuck noted that they did not take into account the movement of the satellite outage due to earth rotation.
5.1.3Overlapping of satellite coverage increases as latitude increases – complete overlap above 62 degrees means no loss of coverage from satellite failure at those latitudes. Show curves of conditional unavailability as a function of user availability.
5.1.4Next is the average unavailability by averaging over latitudes – two different distributions – uniform and Gaussian over core Europe.Results are 2.1 X 10-4 and 6.2 X 10-4, respectively. Also it was noted that these outages are predictable and deterministic, but ATSP’s probably don’t know how to deal with this issue as yet.
5.1.5Histograms shown vs. latitude.Plot of (conditional) outage statistics as a function of latitudeSamples of estimated availability for the two cases mentioned, uniform and Gaussian over Europe: 0.99979 and 0.99938.
5.1.6Mr. LaBerge volunteered to put in an additional slide considering the historical failure rate for Iridium. Mr. Meza presented some information on the health and status of the satellite – this concluded failure rate of one per 18 months. To be conservative we could use the prediction of one per year.
5.1.7Mr. Kerczewski will develop a paragraph for the manual for discussion at the next meeting.
5.2Spectrum Issues.
5.2.1Discussions on SARPs requirement to operate in the safety allocation. Mr. Janksy noted that ITU/BR says that the establishment of a primary service is done. The coordination requirement - Regulation 5.365 regarding MSS space to earth link is subject to coordination under 9.11a. This is the only space-earth downlink that is subject to this – as this is only done for services that are primary. Mr. Jansky concludes that it is effectively protected. The footnotes are part of the allocation. Mr. Witzen noted that 5.367 says it is a primary allocation. Mr. Jacob noted the problem was the agreement under footnote 9.21 and would like to see an explanation in the manual regarding 5.367 and 9.21.
5.2.2Out of band interference. Mr. Hinton notedthat the interference from Inmarsat into Iridium, higher Inmarsat power levels and there is not a guard band between the Inmarsat downlink and Iridium band. Recommendation 1480 deals with Inmarsat interference into Iridium. 1480 needs to be mentioned in the Iridium manual spectrum part as reference. Note that Iridium is allowed 0.6% increase of noise temp into Inmarsat, while Inmarsat wants to be allowed 6% into Iridium.
5.2.3New Iridium Manual Organization - Mr. Meza will split the Manual into separate sections. References to appendices will also be altered. Definitions can stay under the Iridium section as some are Iridium specific. It is also understood that use of the first two sections as standardized text for other satellite systems should not impact the approval timeline. Part I – Chapters 1-4; Part II – Chapters 1-5; Part III – New Satellite Systems (separate Iridium section)
5.2.4Section 2.1.2.1 – Air Traffic Control Services (ATC). DO-210 will be integrated into the report.
5.2.52.3.4 – Reliability/Integrity. Text was added to the reliability section: “delivers intended message within a set amount of time.” However, a question was expressed about whether an IP environment has the same amount of assurance.
5.2.6Section 8 – Comparison of AMS(R)S SARPS and Expected Iridium Performance. Text is substantively approved – however, some edits are required to tighten up the language. Mr. Meza will also revise the section text as needed based on changes made to the Validation Report.
5.2.7Table 8-1. The extra column will remain for now – the end-to-end vs. subnetwork issue is still pending.
6.Next Steps for Completion of the Manual
6.1The subgroup agreed to continue working on the documents via email in advance of the next meeting. Mr. Meza agreed to be the focal point and will amend the text based on meeting discussions. Comments and revisions should be made on the working drafts posted on the meeting web site and will be received until 03 January 2007.
6.2Tentative date for next meeting for Jan 16-18, possibly in Arizona or Texas, Mike will let us know.
7.Working Documents
Document / Source / WP Number / StatusMeeting Agenda / Rapporteur / IRD-SWG06/WP-01 / Approved
Iridium Manual Version 1.34 / Mike Meza / IRD-SWG06/WP-02 / Reviewed
Draft Iridium Validation Report Version 0.2 / Mike Meza / IRD-SWG06/WP-03 / Reviewed
A computation of satellite- induced unavailability for the standard Iridium constellation / Chuck LaBerge / IRD-SWG06/WP-04 / Reviewed
Iridium Manual Version 1.35 / Mike Meza / IRD-SWG06/WP-05 / Reviewed
Draft Iridium Validation Report Version 0.3 / Mike Meza / IRD-SWG06/WP-06 / Reviewed
ITU-R MSS recommendations on MES unwanted emission limits / Secretariat / IRD-SWG06/IP-01 / Background
Priority, Precedence And Preemption For Ams(R)S In The Iridium System / Chuck LaBerge / IRD-SWG06/IP-02 / Background
SNSDU, provider-invoked release and provide-invoked reset as per ISO 8348 / Nikos Fistas / IRD-SWG06/IP-03 / Background
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