Report of ACP, WG-M/14 Meeting

(Montreal, 2-5 June 2008)

ACP WG-S/2REPORT
23-25October 2012

AERONAUTICAL COMMUNICATIONS PANEL (ACP)

WG S – Surface Air-Ground Datalink Communication System

Second Meeting

Montreal, Canada,23th – 25th October 2012

Report of ACP WG-S/2Meeting

Drafted by the Secretary

WG S Meeting 1 Draft Report 2.docPage1

Report of ACP, WG-S/2 Meeting

(Montreal, 23-25 October, 2012)

TABLE OF CONTENTS

1Agenda Item 1: INTRODUCTION

2Agenda Item 3: Review and approval of the agenda

3Agenda Item 4: Review of Action Items from WG-S/1

4Agenda Item 5: Status of Relevant Work Programmes.

4.1RTCA Special Committee 223.

4.2ENRI Status.

5Agenda Item 6: Development of the SARPS

6AGENDA ITEM 7: Development of the Technical Manual

7AGENDA ITEM 9: Date and Place for Next Meeting

8 APPENDIX A – LIST OF ATTENDEES

9 APPENDIX B – Agenda

10Appendix C – Terms of Reference for WG-S

11APPENDIX D – List of Action Items

12APPENDIX E - Items for Follow-Up

13APPENDIX F - Work Assignments for SARPs Development

WG S Meeting 1 Draft Report 2.docPage1

Report of ACP, WG-S/2 Meeting

(Montreal, 23-25 October, 2012)

This meeting report follows the chronological order in which agenda items were disposed.

1Agenda Item 1: INTRODUCTION

The Working Group Rapporteur, Aloke Roy opened the second meeting of WG-S. Following which, general local administrative items were explained to the meeting. This dispensed with Agenda Item 2: Meeting Organizational and Administrative Issues.

2Agenda Item 3: Review and approval of the agenda

The meeting agenda was presented and reviewed. The Agenda was approved having noted that Agenda Items 6.2 and 7.1 were similar and hence Agenda Item 6.1 was struck. The final agenda is given in Appendix B.

3Agenda Item 4: Review of Action Items from WG-S/1

The following provides the actions items and their disposition at WG-S/2:

Action Item 1-1: The Secretary to refer spectrum issues to WG-F for clarification.

Action:CLOSED

Action Item 1-2: The Secretary to inform the FMG and ICAO Regional Officers of their role in supporting AeroMACS frequency management.

Action: No action taken hence OPEN.

Action Item 1-3:Roberto Agrone to check the level of security needed to support multi-cast.

Action: This item generated a great deal of discussion which is summarised as follows.

  • It was pointed out by Aloke Roy that multicast was seen as vulnerable from a security perspective and hence many felt that it should be dropped.
  • It was agreed that this would have an impact on system loading especially in the future when the system would be used to transfer large files such as airport maps to multiple aircraft. Hence it should be retained.
  • The response to this was that work on multicast would affect both MOPS and SARPS development, delaying each by at least a year.
  • It was pointed out that basic standards for multicast existed, albeit without security, however there were two further concerns. The first being the lack of any test cases to allow validation of the resulting standards, i.e; MOPS and SARPS. The meeting noted that this situation existed despite the fact that an “aviation profile” existed which included multicast. The second, the fact that the standards may change due to the validation activities and improvements to the technology. The latter point was aggravated by the fact that the WiMAX forum had only considered the 2005 version of the WiMAX (IEEE 802.16 standard) and not the 2009 version, hence problems could be expected.
  • The possibility of validation activities being conducted by the civil aviation community was raised. It was soon made clear to the meeting that the civil aviation community did not have the resources for this and had to rely on the work of other bodies such as the WiMAX Forum, who did not attach any urgency to this.
  • The following solution was proposed:
  • ICAO to produce high-level SARPS calling for multi-cast and also work on more detailed material for companion manual. The former would not be affected by technical changes while the latter could be amended in as little as 12 months.
  • It was also pointed out that the WiMAX profiles were based on IPV4, while the ATN/IPS was based on IPV6. This was noted without any clear resolution, except that the technology existed to interface systems based on the two standards.

Regarding the core of this Action Item, it was pointed out that EUROCONTROL had developed a “Technical Note” on security hence this action item could be CLOSED.

Action item 1-4: Robert Witzen to refer issues of interference with radio-telemetry systems to WG-F. Action: No action taken hence CLOSED.

Action Item 1-5: The Secretary to coordinate with Armin Schlereth to obtain information on the SANDRA project. Action: No action taken hence CLOSED

4Agenda Item 5: Status of Relevant Work Programmes.

4.1RTCA Special Committee 223.

Aloke Roy presented WP## describing the status of SC-233 activities. This paper presented a history of progress to date and also made the point that the FAA, EURCONTROL and several airlines had expressed strong interest in AeroMACS and were anticipating an IOC in 2016.

4.2ENRI Status.

#### #### presented WP04 which described the efforts taken by ENRI to test and validate an AeroMACS system. Some key aspects of the test were an evaluation of the performance at the aerodrome perimeter, especially in cases where this was affected by the shadowing effects of building and other obstacles. Results of these tests could provide useful guidance material particularly in the area of implementation. Another item of concern was the use of COTS equipment, a major goal of the AeroMACS initiative. The main problem being that the AeroMACS profile for aviation was based on the 2009 IEEE Standard while the only available COTS equipment conformed to the 2005 or even the 2004 standard, as industry had no compelling reason to produce the more complex equipment. This of course affected the validity of any test done using COTS equipment.

For baseline standard, WiMAX Forum has announced the baseline standard is defined in the document, which WiMAX Forum has published as an SRD and is defined such as “baseline standard for system profile is IEEE802.16-2004 amended by IEEE802.16-2005 and corrected by IEEE802.16-Cor2/D3 with any exceptions to the above standard baseline including those from IEEE802.16-2009, being specified in the document SRD, which should be used as pointer to the updated reference”. For the actual products in operation, WiMAX BS and MS venders now have been supported in accordance with WiMAX Forum SRD documents.

5Agenda Item 6: Development of the SARPS

The meeting then dealt with WP02 AeroMACS draft SARPS. This was a point by point review of the work done. As well as this Agenda Items 6.3, 6.4 and 6.5 were also dealt with. Changes to the SARPS were captured by the Secretary and will be incorporated into a revised draft. The salient points of the discussions were as follows:

  • The use of references to RTCA/EUROCAE document raised a number of issues, namely:
  • Industry documents cannot be expressly referenced in SARPS but can be referenced in “notes” to SARPs. In the latter case a definite document number is needed or else the document must be mentioned by name. This led to the following action items:

ACTION ITEM 2-1: Secretary to find out of document numbers as well as titles are needed in “notes” to SARPS.

ACTION ITEM 2-2: Depending on the outcome of AI 2-1, Secretary to contact RTCA and EUROCAE to find out if document numbers can be reserved in advance of publication.

  • A determination was made to include “power-up time”, in the definition of Network Entry Time, except in the case where network connections are temporarily lost.
  • A lengthy discussion took place on the use of definitions for Mobile Station (MS) and Subscriber Stations (SS). The agreed solution was to use one definition, that for MSs but extend the definition to include the case where MSs are used for fixed installations. This was possible as all MSs would use the standard for mobile communications as opposed to that for fixed.
  • WP05 dealing with interference was presented. Key points included interference “hot spots” due to aggregate emissions from geographically distributed MSs. This analysis was based on a classification of airports into large, medium or small, each with different AeroMACS configuration requirements.
  • Regarding interference, two operating scenarios were presented one which provided optimum performance for all airports (Scenario A) and another with reduced performance at small airports (Scenario B). Given the adaptive nature of AeroMACS it was difficult to theoretically predict the performance of AeroMACS under Scenario B.
  • The question arose how to present information in the SARPS related to power output and hence interference potential. Options included details on transmitter power along with antenna configurations or a simple set of EIRP masks. This was unresolved and led to the following action item.

ACTION ITEM 2-3: Rafael Apaza to consider the representation of power output vs interference potential and propose a solution.

  • The discussion on this subject extended to the various airport scenarios, i.e; small, medium or large. It was pointed out that these distinctions could influence implementation decisions and hence should be avoided in the SARPS and other documents. This led to the following Action Item:

ACTION ITEM 2-4: Ward Hall to determine generic power/emission requirement. STATUS: CLOSED during meeting. The original submission was later modified by the meeting and will be included in final SARPS.

  • Regarding paragraph 2.4.2.3, regarding the use of an second channel plan, it was agreed that an explanation in the form of a “Note” was needed. This led to the following Action Item:

ACTION ITEM 2-5: Luc to provide note on reasons for selection of second channel plan.

  • Regarding paragraph 2.4.3.1, it was agreed that these requirements should be moved to the MOPS. As this was not allocated to an individual it resulted in the following Item for Follow Up:

ITEM FOR FOLLOW UP 2-1: WG-S to ensure that the emission power table in 2.4.3.1 be included in the RTCA/EUROCAE MOPS.

  • Regarding 2.4.4, regarding spectral emission, it was agreed that the mask from the MOPS should be included. This led to the following action item:

ACTION ITEM 2-6: Bruce to provide Secretary with spectral mask for inclusion in SARPS.

  • On the subject of availability, the point was raised that the requirement as stated did not cover major contingencies or “acts of God”, i.e; fires, floods, accidents, which would cause the basic requirement to be exceeded. It was proposed that this could be dealt with by expressing as a %, the time that the general availability time must be met. This led to the following action item:

ACTION ITEM 2-7: Rafael to re-define availability with a percentage figure to allow to cover contingencies when the basic requirement would not be met.

The issues of rapid intermittent failures was also raised. There was some debate as to whether these could be considered outages and finally it was agreed that they should be treated as such. In WP08, the point was also raised that an allowable frequency of outages had not been defined (only a maximum duration). This led to a further action item:

ACTION ITEM 2-8: Natalie and Rafael to determined suitable frequency of outages, i.e; per week/per month, etc. and also a requirement to cover rapid intermittent failures.

  • On the subject of data transit delays, it was pointed out that:
  • the uplink and downlink requirements were identical and could be combined.
  • The requirement only applied to the highest priority traffic.

This led to the following action item:

ACTION ITEM 2-9: Secretary to combine transit delay requirements and re-draft to indicate that they only apply to the highest priority traffic.

  • On the subject of data integrity it was pointed out that:
  • the uplink and downlink requirements were identical and could be combined.
  • The requirement was expressed in terms of SNSDU which had yet to be defined.
  • A clear definition of SNSDUs would also clarify considerations on priority, precedence and pre-emption.

This led to the following Item for Follow Up:

ITEM FOR FOLLOW UP 2-2: WG-S to define digital data, in terms of the smallest component to be handled by the AeroMACS protocols.

  • On the discussion on interference, the issues of received sensitivity arose. It was agreed by the meeting that sensitivity figures should be included. A table of figures was provided for the various modulation schemes. These will be included in the SARPS with the advice that the first two modulation schemes are only optional for mobile stations.
  • The subject of prioritization and pre-emption was raised a number of times during the meeting, especially with regard to WP09 which raised the issue of resource contention. The subject revolved around the issue as to whether pre-emption involved discarding traffic. It was finally agreed that traffic related to the safety and regularity of flight could not be discarded. This led to a general conclusion that precedence and not pre-emption was appropriate to AM(R)S traffic. It was accepted that this could be accommodated with slight changes to the SARPS but that the main detail should be provided in the Guidance Material. In order to make progress on this issue, further investigation is needed which led to the following action item:

ACTION ITEM 2-10: Aloke Roy to contact WiMAX forum to find out how pre-emption has been defined for WiMAX.

6AGENDA ITEM 7: Development of the Technical Manual

7.1: Concept of Operations Work Paper by EXELIS

Bruce Eckstein presented WP07 which provided a draft concept of operations for AeroMACS. This took the form of a comprehensive description of aircraft communications while on the tarmac either at the commencement or end of a flight. It then provided a suggested list of the applications to be supported by AeroMACS. The latter generated some discussion with the following items added to the list:

  • Flight Operations Quality Assurance (FOQA)
  • VOIP for safety and regularity of flight.

It was agreed that Navigation Database updates should be included in the AeroMACS applications. This led to the following action item:

ACTION ITEM 2-11: Aloke Roy to provide text on Navigation Database updating.

WP03 was then presented by Bruce Eckstein. This paper provided additional material to that provided in WP07, namely a description of a possible frequency scanning and acquisition process. This led to a lengthy discussion the salient points of which were as follows:

  • Frequency scanning and acquisition algorithms were not generic, as each manufacturer has implemented a proprietary algorithm. Hence they cannot be described in this level of detail.
  • It emerged that the duration of the scanning and acquisition process and hence the network entry time was uncertain.
  • The only way to eliminate this uncertainty would be to conduct validation testing. Europe is not expected to complete this until Q3 2013.
  • In order to provide adequate margin, it was agreed to extend the network entry time requirement to 90 seconds as this would have no operational impact. If tests prove that this is conservative, a lower level could be chosen.
  • It was also pointed out that scanning/acquisition times will vary. Hence it was agreed that a probability needed to be attached to the network entry requirement.
  • It was agreed to provide a placeholder for a probability factor in the network entry time requirement.

In order to resolve the uncertainty over network entry times the following action items were levied:

ACTION ITEM 2-12: Luc Lommaert to monitor activities in Europe and provide indications on prospective network entry times and their probability.

ACTION ITEM 2-13: Hitachi to make best efforts to perform tests on network entry times using a variety of scenarios.

Another result of this discussion was that the material in WP07 will be considered for possible inclusion in the Guidance Material if found to be valid.

WP07 was presented by the Secretary. The main point of this paper was to explain the interaction between AeroMACS and the other communications media available on the airport surface. It was pointed out that this material should be placed in the ATN Manual rather than the AeroMACS manual. This led to the following action item:

ACTION ITEM 2-14: Secretary to modify WP07 for inclusion in Doc 9896 and propose this to WG-I.

7.2: Priority and Pre-Emption Working Paper from Honeywell

WP## was presented by Aloke Roy. This paper contained a table which provided a mapping of the ATN Transport Layer priorities to those of AeroMACS. It was pointed out that the two are inverted, i.e; one is acending, the other descending.

Other points made were that Distress and Urgent communications are not included in the AeroMACS priorities.

The suggestion was made to include VOIP and fixed applications in the list. It was further pointed out that the fixed applications would have different priorities. The table was updated at the meeting according to these suggestions. It was agreed that further work would be needed, which led to the following action item.

ACTION ITEM 2-16: Aloke Roy to amend table to reflect priortisation used by the WiMAX forum.

ACTION ITEM 2-17:Secretary to present table to WG-I for inclusion in Document 9896.

7.3: Institutional Issues

The secretary explained to the meeting that no progress had been made on this since the last telecom. The status now is that the brief paper on institutional issues will be included as an appendix to the Manual.

7.3: Working Session to develop the Technical Manual

The group collectively developed a the following outline for the Technical Manual:

OUTLINE FOR MANUAL:

1)General

  1. Constraints
  2. Reference System

2)Guidance Material

  1. Concept of Operations
  2. Operational Scenario
  3. Applications supported
  4. System Architecture
  5. Ground Architecture
  6. Aviation profile
  7. Implementation
  8. Siting considerations
  9. Interference minimization
  10. Antennae/MIMO
  11. Prioritisation
  12. Hand-off (AT4 wireless genericised)

3)Technical Spec:

  1. Performance
  2. Power levels,
  3. Interference
  4. Hand-off
  5. Routing and discovery
  6. Security framework.
  7. Prioritisation
  8. Upper layer interfaces
  9. Frequency allocation/Channelisation

7AGENDA ITEM 9: Date and Place for Next Meeting