AMCP/& Draft NGSS Sarps
2004-08-29
Aeronautical Communications Panel
Working Group M – AMSS Sub-group
Prepared by Dave Sim
1. This paper presents a revised proposal for the reorganization of the AMS(R)S Standards and Recommended Practices, following a review of the RF characteristics by ACP WG-F both in August 1993 and August 1994 (WG-F/10 and WG-F/12), and following a review of a previous proposal by WG-M in November 2003 (WG-M/8).
2. It is proposed that this draft be the basis for a working paper to be discussed at the next meeting of WG-M which is expected to be in October 2004. The AMSS sub-group is invited to consider this material and to coordinate a submission to WG-M through the author. Comments and suggestions may be shared with the sub-group by email.
3. A main consideration when proposing these standards is the protection of radio spectrum used for safety services. The Annex should contain the minimum specifications required to enable the provision of safety services, providing reasonable immunity from other spectrum users, and at the same time to contain the service within its allocation so that is does not cause harmful interference to other users. It has been of value in the past to have available in ICAO Standards the RF characteristics applicable to systems in order to enable their licensing by the radio regulators. This is a major milestone when a system is proposed for an aeronautical safety service.
4. Considering the “Guidelines for ANC Panels for the development of SARPs material”, detailed technical specifications for specific types of AMS(R)S will be contained in Manuals. In the spirit of allowing for service based system characteristics, ICAO has determined that a proliferation of complex system specifications in the Annexes is not desirable. The majority of text that is presently in Annex 10, Volume III, Chapter 4 will be transferred to a Manual. The accompanying Guidance Material (green pages) will also be included in the Manual.
5. When WG-A of the AMCP was tasked to develop “core” standards for a next generation satellite systems, it took the approach that a small set of standards would be appropriate to deal with spectrum requirements and system performance. Service providers could then map their services to these standards and could comply with the detailed technical specifications in a Manual. This has been the approach that we have taken in proposing a reorganization of the existing Annex 10, Volume III, Chapter 4.
6. Let us review the results of the previous meeting of WG-M, as contained in the report of WG-M/8, Appendix M.
6.1
Comment No. / Section / Paragraph / Comment12.1 / General / This section contains some definitions used in the rest of Chapter 4. However other terms used in the Chapter are defined elsewhere in Anx 10 such as Vol II Chapter 1 (e.g. AMS(R)S, AMSS) or in Vol III Chapter 1 (e.g. AES, GES). It is proposed that one common definition list is developed.
As Annex 10 grew into five volumes, it became somewhat awkward to locate definitions. A consolidation of all definitions into a single list might be desirable. A single list would be easier to maintain, but maycause the printing of another document, or the repetition of the entire list in each volume. ICAO is asked to consider the merits of this.
6.2
12.1 / Total transfer delay / The name of this term is very generic but the explanation is specific to voice communications. The explanation also suggests an implementation i.e. the ‘speech’ is presented to the AES or GES. Also the definition of subnetwork (Network) applies only to packet data. Suggested rewording-Total voice transit delay - …….the speech signal is presented to the AES or GES and concluding at the instant that the speech signal…… This delay could include vocoder processing time, physical layer delay RF propagation delay and any other delays within the AMS(R)S satellite system.
This rewording is incorporated in the attached revised draft.
6.3
12.3.2.2.1 / Interference to other AMS(R)S / Reword to ‘….harmful interference to an AES providing AMS(R)S on the same aircraft oron a differentother aircraft’.Rationale – in the transition phase it is possible that 2 separate AMS(R)S services are in operation e.g. AMSS and NGSS. In fact this section is covered by para. 12.2.3.2 anyway.
This rewording is incorporated in the attachedrevised draft.
6.4
12.3.2.2.1 – Note 1 / Interference to other AMS(R)S / To future-proof the SARPS it is proposed that this Note is deleted or reference to RTCA DO-215A Change 1 is changed to ‘…the latest version of RTCA document DO215’This rewording is incorporated in the attached revised draft.
6.5
12.4.1 / Priority and Preemption / ‘….immediate availability…’ should be quantified.Wording such as “availability as appropriate to meet operation requirements” might be more suitable. Then, ANS providers are free to establish operation needs, and CNS providers are able to tailor their services to meet these needs. Rewording is incorporated in the attached revised draft.
6.6
12.5.1.1 / Recommendation / The figure of 1500 knots was introduced when supersonic flight was used. That option no longer seems needed so should this recommendation be deleted ?12.5.2.1 / Recommendation / The figure of 1.2g is very demanding (and uncomfortable) – what is the justification for this value ?
As above, and for this entire section 12.5 Signal Acquisition and Tracking, wording such as “…appropriate to meet operation requirements” allows for the refining of ANS requirements and CNS services to meet needs. Therefore, it is suggested that the recommendations be deleted and that the standards be modified as shown in the attached revised draft.
6.7
12.6.2.1 / Failure Notification / ‘NGSS’ should be ‘AMS(R)S satellite service’.The acronym NGSS has been replaced by AMS(R)S in the attached revised draft.
6.8
12.6.2.3 / Failure Notification / Proposed reword - The system shall annunciate a loss of communications capability within 30 seconds of the time when it detects such a loss.Rationale – the time taken to detect to loss is not specified as written e.g. it could take many hours to detect a loss.
This rewording is incorporated in the attached revised draft. The sub-group may wish to reconsider having any specific value or perhaps to have a reference to operational requirements.
6.9
12.6.4.1.2 / Delay Parameters / No specific values should be given in this section and generic parameter references given only. The current values, whilst maximum, give an impression of the achieved satellite performance. This could limit the perception of where satellite systems could be used. The RTCA NGSS MASPS (DO-270) do not give performance values but expect each specific system to define their own. Reference to RTCA MOPS/MASPS could be considered here.12.6.4.1.2.1 / Connection Establishment / Even though a figure should not be quoted, the value of 60 seconds in not in compliance with the existing AMSS SARPS. The maximum figure for 600b/s is 70 seconds in 4.7.2.2.1.1.
12.6.4.1.2.2 to 12.6.4.1.2.10 / Delay values / Even though figures should not be quoted, the values quoted in these paragraphs are not consistent with the table in the existing AMSS SARPs section 4.7.2.2.2.1. Some figures are higher and some are lower. If the figures are to be retained they should be at least equal to or better than those achieved by the existing AMSS.
Wording could be changed to refer to operational requirements, and a Note could be added to point to guidance that is available in RTCA DO-270. Such rewording is incorporated in the attached revised draft.
6.10
12.6.4.1.3.1 / Residual error rate / Even though figures should not be quoted, the new values are very low for a packet data system even if it is consistent with the existing AMSS.12.6.4.1.3.2 / Comment under this paragraph – No these provisions are not applicable.
12.6.4.1.3.3 and 12.6.4.1.3.4 / Even though figures should not be quoted, these values are relevant to the existing AMSS and should not be repeated.
Suggest that the section 12.6.4.1.3. Integrity be expressed in terms of operation requirements. A rewording is included in the attached revised draft.
6.11
12.6.5.1.1.1 and 12.6.5.1.1.2 / Call Processing / Even though figures should not be quoted, these values are relevant to the existing AMSS and should not be repeated12.6.5.1.2 / Call Processing / The maximum figure that has been discussed in AMCP WG-C in the past was 400 mS – the value quoted here is higher and should be reduced.
As above, with a reference to operational requirements. A rewording is included in the attached revised draft.
6.12
12.7.3 / Voice service interfaces / The requirement to interface to an external telephony network (i.e. PSTN) is not a requirement. An AMS(R)S only system may only need to interface the ATS voice network. The requirement should be deleted or made more general.This has been deleted in the attached revised draft.
6.13
12.6.5.1.4.1 / Blocking Probability / The value of 0.01 may be too high for high density environments.Section 12.6.5.1.4 Voice Capacity can also be simplified to a statement on operational requirements. A rewording is included in the attached revised draft.
6.14
General / Performance values / For the core SARPs to be really generic, what is important is to be able to meet the operational requirements for the service that are intended to use. It is recommended to consider the restrictions that specific values may be imposing for the future use and identify the best solution to be able to support also new satellite systems.Agree fully.
7. Actions
7.1 The sub-group is asked to comment on the incorporation of recommendations from WG-M/8 in the attached draft SARPs. In particular, comments on the removal of quantified parameters in favour of operational requirements are sought.
7.2 Under 6.1 regarding a consolidated list of definitions for Annex 10, ICAO is asked to provide guidance.
7.3 Under 6.8 consider whether failure notification time should have a specific value.
7.4Attention is drawn to 12.3.2.3.2 in the attachment and the editorial comment regarding protection of GNSS. The following comment was transmitted to WG-F at its meeting August 23-27, including some material from the report of AMCP/8. Feedback from WG-F is TBD. Note that this is an outstanding work item for WG-M. In particular, existing specifications for AMSS in Chapter 4 may need to be revised in consideration of potential interference to GLONASS. The sub-group is asked to consider a response to the report from AMCP/8
“The above editorial comment [in 12.3.2.3.2] points out an inconsistency between, on one hand, some requirements for legacy AMSS, for GNSS, and proposals that were discussed at AMCP/8, and on the other hand, the material that was developed by WG-A for NGSS. It may also be noted from the report of AMCP/8, Agenda Item 5 Review of existing ICAO material on air/ground communication systems, the following:
5.2.3 The meeting considered proposed amendments to the AMSS SARPs on:
a) aircraft earth station receiver interference susceptibility;
b) the maximum harmonic, discrete spurious and noise density levels;
c) the maximum intermodulation product levels (Tables 4.3 and 4.3bis of the AMSS SARPs); and
d) the data terminal equipment (DTE) effect on DCE restart rates and the DTE effect on DCE flow control transfer rates (Tables 4-30 and 4-43 of the AMSS SARPs.
5.2.3.1 The meeting could not agree to the amendments under b) and c) above since these would not provide the required protection of GLObal NAvigation Satellite System (GLONASS) receivers. The meeting, further considering that the amendments under d) above address material that would be transferred to the AMSS Manual on detailed technical specifications, referred these proposals back to WG-M for further consideration.”
7.5 Attention is drawn to 12.4.2 and the editorial comment regarding levels of priority. The sub-group is asked to consider whether a specific value is needed or whether it should be expressed in terms of operational requirements, or perhaps in terms of the ATN standards.
Attachment – draft working paper for WG-M/9
Aeronautical Communications Panel
Working Group M
Ninth Meeting – [TBD]
Agenda Item : Development of AMSS Core SARPs and guidance material (Manual)
Proposed replacement text for AMSS SARPs
Prepared by Dave Sim
Presented by Robert Witzen
- The meeting is invited to review the attachment and provide direction to the sub-group on the core AMSS SARPs. It should be noted that final formatting and paragraph numbering will be undertaken by ICAO. Comments have been included in the text to support the review. These will be removed from the final draft. The restructuring of the legacy AMSS material into a technical manual will continue via the sub-group.
____
Insert text as follows:
[Highlights and strikeouts reflect changes from the draft NGSS material that was developed by AMCP.
This entire text, with comments and strikeout text removed and highlights as normal text,
would replace the existing Chapter 4]
CHAPTER 4.12. ALTERNATIVE PROVISIONS FOR AERONAUTICAL
MOBILE SATELLITE (R)* SERVICE
Note 1.— This chapter contains Standards and Recommended Practices applicable to the use of Aeronautical Mobile-satellite (R) Service next-generation satellite system (NGSS) communications technologies to support the aeronautical mobile-satellite (R)* service (AMS(R)S). The Standards and Recommended Practices of this chapter are service- and performance-oriented and are not tied to a specific technology or technique. They are intended to provide alternative means of meeting AMS(R)S requirements, independent of the Standards and Recommended Practices of Annex 10, Part I, Volume III, Chapter 4.
Note 2.— Multiple service providers may offer AMS(R)S, either according to the Standards and Recommended Practices of Annex 10, Part I, Volume III, Chapter 4 or according to those of this Chapter.
Note 23.— Additional information and guidance is provided in the Manual on Alternative Provisions for AMS(R)S.
12.1 DEFINITIONS
AMS(R)SNext-generation satellite system (NGSS).- A satellite communications system that provides AMS(R)S in conformance with the provisions of this Chapter. These services can be voice, or data, or both. An NGSSAMS(R)S satellite system may provide non-AMS(R)S communications. An NGSSAMS(R)S satellite system includes AESs, satellites, GESs and network control system facilities that perform administrative and operational management functions.
Connection establishment delay. - Connection establishment delay, as defined in ISO 8348, includes a component, attributable to the called Subnetwork service user, which is the time between the SN-CONNECT indication and the SN-CONNECT response. This user component is due to actions outside the boundaries of the satellite Subnetwork and is therefore excluded from the AMS(R)S specifications.
Data transfer delay (95th percentile). - The 95th percentile of the statistical distribution of delays for which transit delay is the average.
Data transit delay. - In accordance with ISO8348, the average value of the statistical distribution of data delays.
Network (N). - The word “network” and its abbreviation “N” in ISO 8348 (first edition) are replaced by the word “Subnetwork” and its abbreviation “SN”, respectively, wherever they appear in relation to the Subnetwork layer packet data performance.
Residual error rate. - The combination of the probability of undetected error, the probability of undetected loss of an SNSDU, and the probability of an undetected duplicate SNSDU.
Satellite system service area. - A portion of the Earth’s surface within which a satellite-based communications system satisfies the standards of this Chapter. Depending on its design, a system may provide discontinuous service areas. {Comment: replaced in the body of the text by designated operational coverage – DOC }
Spot beam. – Satellite antenna directivity whose main lobe encompasses significantly less that the earth’s surface that is within line-of-sight view of the satellite. May be designed so as to improve system resource efficiency with respect to geographical distribution of user earth stations.
Subnetwork (SN). See Network (N)
Subnetwork service data unit (SNSDU). - An amount of subnetwork user data, the identity of which is preserved from one end of a subnetwork connection to the other.
* route
Total transfer delay. - The elapsed time commencing at the instant that speech is presented to the AES or GES and concluding at the instant that the speech enters the interconnecting network of the counterpart GES or AES. This delay
includes vocoder processing time, physical layer delay, RF propagation delay and any other delays within the AMS(R)S Subnetwork.
Total voice transit delay - … The elapsed time commencing at the instant that the speech signal is presented to the AES or GES and concluding at the instant that the speech signal enters the interconnecting network of the counterpart GES or AES. This delay could include vocoder processing time, physical layer delay RF propagation delay and any other delays within the AMS(R)S satellite system.
Note.— The following terms used in this chapter are defined elsewhere in Annex 10:
Aircraft earth station (AES): defined in Annex 10, Volume III, Chapter 1.
Aeronautical telecommunication network (ATN): defined in Annex 10, Volume III, Chapter 1.
Aeronautical mobile-satellite service (AMSS): defined in Annex 10, Volume II, Chapter 1.1.
Aeronautical mobile-satellite (R)* service (AMS(R)S): defined in Annex 10, Volume II, Chapter 1.1.
Data transfer delay (95 percentile): defined in Annex 10, Volume III, Chapter 4.7.2.1. { Comment: moved to Definitions]}
Data transit delay: defined in Annex 10, Volume III, Chapter 4.7.2.1. { Comment: moved to Definitions}
Ground earth station (GES): defined in Annex 10, Volume III, Chapter 1.
Near-geostationary orbits: defined in Annex 10, Volume III, Chapter 4.1.{ Comment: not used }
Spot beam: defined in Annex 10, Volume III, Chapter 4.1.{ Comment: moved to Definitions}
Subnetwork layer: defined in Annex 10, Volume III, Chapter 6.1.
Subnetwork service data unit (SNSDU): defined in Annex 10, Volume III, Chapter 4.7.2.1 {Comment: see Definitions 12.1}
12.2 GENERAL
12.2.1 When an NGSSAMS(R)S satellite system is operated to provide AMS(R)S, it shall conform to the requirements of this Chapter.
12.2.1.1 Recommendation: To ensure sufficient protection of safety-related CNS systems, NGSSAMS(R)S satellite system aeronautical equipment not operating to provide AMS(R)S should comply with the provisions of 12.3.2 and 12.3.3 of this standard.
12.2.1.2 The AMS(R)S satellite system shall support packet data service, or voice service, or both.
12.2.2 Requirements for mandatory carriage of NGSSAMS(R)S satellite system equipment including the level of system capability shall be made on the basis of regional air navigation agreements which specify the airspace of operation and the implementation time-scales for the carriage of equipment including the appropriate lead-time.
12.2.3 The agreements indicated in 12.2.2 shall provide at least two years’ notice of mandatory carriage of airborne systems.