Comments on WP2



AMCP WGC4/WP4

AERONAUTICAL MOBILE COMMUNICATIONS PANEL (AMCP)

Working Group C – 4th meeting

Montreal, Canada

27-30 May 2002

Agenda Item 4: Report to AMCP/8

Comments on WP2 (Draft WGC Report to AMCP/8)

Presented by Philippe Renaud

Summary

This working paper contains a comments and proposed changes on the report under development by WGC as an input to AMCP/8. The proposals are shown in redline/strikeout format.

AMCP-WG C report

Communication scenarios from present until and beyond 2010

The need to achieve a common interoperable communication infrastructure beyond 2010

Modifications (identified by revisions marks) and comments (identified by >) from Philippe Renaud Eurocontrol Ed

Executive Summary 3

1.0 BACKGROUND 4

COMMENTS TO: KORS@ 4

2.0 INTRODUCTION TO REPORT 4

COMMENTS TO: KORS@ 4

3.0 SCOPE OF REPORT 5

COMMENTS TO: KORS@ 5

4.0 THE EVENTS SINCE THE 10TH AIR NAVIGATION CONFERENCE 5

COMMENTS TO: ACAPRETTI@ICAO.INT 5

5.0 PRESENT SITUATION 5

COMMENTS TO: PHILIPPE.CREBASSA@AVIATION-CIVILE.GOUV.FR 5

INTRODUCTION 5

SYSTEMS UNDER CONSIDERATION 5

GENERAL SYSTEMS OVERVIEW 6

FUNCTIONAL DESCRIPTION MATRICES 8

SERVICE TYPES FOR COMMUNICATIONS 1

PHASE OF MOVEMENT: 3

STATUS OF ONGOING ACTIVITIES 4

PROGRAMS AND FUTURE ACTIVITIES 5

ISSUES RAISED 6

6.0 THE PROBLEM STATEMENT 7

COMMENTS TO: KORS@ 7

7.0 DETERMINING THE FUTURE NEED 7

COMMENTS TO: KORS@ 7

THE PERCEIVED NEED 7

THE OPTIMUM INFRASTRUCTURE. 8

8.0 OPERATIONAL COMMUNICATION REQUIREMENTS 8

INTRODUCTION 8

OPERATING CONCEPT 8

EXISTING COMMUNICATION OPERATING CONCEPT 9

REQUIRED COMMUNICATION PERFORMANCE 12

QUALITY OF SERVICE 12

USERS 13

USER INFORMATION 13

HUMAN - MACHINE REQUIREMENTS 14

CAPACITY 14

TECHNOLOGIES 15

9.0 COMMUNICATION SERVICE REQUIREMENTS 15

COMMENTS TO: DELRIEU_ALAIN@DNA.DGAC.FR 15

INTRODUCTION: 15

COMMUNICATION SERVICE CHARACTERISTICS 15

COMMUNICATION PRECEDENCE, PRIORITY AND ACCESS 15

RF CHARACTERISTICS 15

EMISSIONS 15

SIGNAL ACQUISITION AND TRACKING 15

COMMUNICATION LOADING 15

COMMUNICATION ACKNOWLEDGEMENT REQUIREMENTS FOR VOICE AND DATA 16

VOICE COMMUNICATION SET-UP AND PROCESSING DELAY 16

PACKETIZED DATA TRANSMISSION 16

ATN COMPATIBILITY AND STANDARDIZED VOICE INTERFACES 16

10.0 FUTURE ALTERNATIVES 16

COMMENTS TO: PHILIPPE.RENAUD@EUROCONTROL.BE 16

INTRODUCTION 16

SYSTEMS TO BE INTRODUCED IN THE FUTURE COMMUNICATION ARCHITECTURE 16

POINTS/CONSTRAINTS TO BE CONSIDERED IN A FUTURE COMMUNICATION ARCHITECTURE 1

11.0 SCENARIOS 2

COMMENTS TO: PHILIPPE.RENAUD@EUROCONTROL.BE 2

SCENARIO 1 3

SCENARIO 2 6

SCENARIO 3 8

12.0 INSTITUTIONAL ASPECTS 9

COMMENTS TO: CLOISY@ESTEC.ESA.NL 9

STANDARDISATION 9

CERTIFICATION 10

RADIO SPECTRUM ALLOCATION 10

IMPLEMENTATION PLANING 10

SERVICE PROVISIONS 10

COSTS CONSIDERATIONS 10

INTELLECTUAL PROPERTY 10

13.0 SUMMARY AND CONCLUSION 10

14..0 RECOMMENDATIONS TO AMCP/8 10

APPENDICES 10

APPENDIX X: DEFINITIONS AND ACRONYMS 10

APPENDIX Z: INFO 10

REFERENCES 11

Executive Summary

1.0 Background

Comments to: kors@

The lack of a clear global operational ATM concept increases the technological and investment risk to the aviation community for the necessary supporting communication, navigation and surveillance infrastructure. Not having clear stated operational requirements causes the development of the various CNS variants to meet perceived operational requirements in the anticipation that it will at least meet a subset of the overall requirements. For the communication element this has led to the development and standardisation of competing technologies for voice and data link services with complementary and overlapping characteristics.

Initially these systems might bring early benefits, however it could result in a patchwork of different Regional and National communication networks increasing the overall infrastructure costs whilst reducing the quality of service. AMCP/7, recognizing the risk of the proliferation of system solutions, has assigned the following tasks to ICAO WG-C:

a) to explore the long-term system requirements for aeronautical VHF systems in the light of the ATM concept, scenarios for all flight and operational requirements for implementation for beyond 2010 to be developed by the ATMCP, and;

b) to explore the likely airspace user needs for aeronautical VHF systems beyond 2010.

The tasks are related to the VHF systems after 2010, however they can’t be properly addressed without due consideration to aeronautical communications services in other radio frequency bands.

Improved communication is the enabler and not the end-goal, hence communication is a pure cost element within the overall CNS/ATM system concept. Therefore the introduction of the future communication infrastructure should be guided by:

a) The operational need in terms of performance and capacity and

b) The optimum infrastructure to meet this need.

Considering the lead-time required to deploying the necessary infrastructure for a successful implementation, transition planning is essential to provide a road map towards a common global interoperable communication infrastructure which can evolve in capacity and services with the air traffic growth.

2.0 Introduction to report

Comments to: kors@

The report is intended to make an inventory of the problems the aviation community is facing with through the introduction of communication technology, with the objective to provide guidance towards a harmonized global communication infrastructure.

The report provides and overview of the present situation that is being used as the basis for the various implementation scenarios towards 2010 through an assessment of already ICAO standardized systems. These scenarios are analyzed on their merits in conjunction with the developments in the mobile communication industry of 2.5, 3 and possibly 4th Generation systems.

3.0 Scope of report

Comments to: kors@

The report is basically constrained to communication service for Air Traffic Management (ATM) including Air Traffic Control (ATC), Air Traffic Services (ATS) and Airline Operational Communication (AOC) with the VHF communication as the initial focal point. Where However, since frequency, increased services and capacity needs or and integration aspects are involved other aeronautical communication services and systems will were felt necessary to be included in the considerations.

Within the ATM CNS service elements only the communication service element and the surveillance service element are considered. Navigation services are not considered since, for safety and certification issues as well as due to their specific requirements, it is felt essential to support them on dedicated systems. Furthermore, the surveillance service element is only considered to the extent that is supported through a data communication system.

The report is written as a self-contained document with the caveat that appropriate qualitative and quantitative statements are documented in reference material.

4.0 The events since the 10th Air Navigation Conference

Comments to: acapretti@icao.int

5.0 Present Situation

Comments to: philippe.crebassa@aviation-civile.gouv.fr

Introduction

Considering the difficulty to state future operational performance requirements for mobile communication and surveillance, an evolutionary way has to be sought to improve the aeronautical communication capability and capacity. Before this, an inventory of presently operating systems and ongoing and planned trials for newly standardized technologies is needed. However, the picture of the first step toward a new communication infrastructure is becoming more clear, namely: in addition to the present operating voice systems, AMSS and HF data link for long range communications and VHF VDL Mode 2 for non-prioritynon-safety critical communications .

This chapter intends to make an inventory on the status of presently current ICAO standardized systems mobile communication systems, as part of the Annex 10, Volume III.

At present almost every communication exchange is conducted by voice: ATC, ATS (ATIS, VOLMET…). The infrastructure supporting them is mainly based on the 25 kHz and 8.33 kHz VHF DSB-AM technologies. HF is also used in oceanic and remote regions.

For ATS, limited use is made of data communication using ACARS, ARINC 622, 623 Protocols over VHF, and AMSS.

Systems under consideration

This section provides a high level technical and operational description of the ICAO standardized mobile communication systems. Besides a brief introduction for each of them, the main technical information is categorized as a set of tables. The structure, scope and content of the tables have been defined in accordance with the objectives of this report.

General Systems overview

VHF 25 kHz and 8.33 kHz DSB-AM

25 kHz

VHF 25 kHz DSB-AM has been implemented for all international flights and supports all current voice communications between controllers and pilots, pilot and pilots, and broadcast Flight Information Services (e.g. ATIS), and airline operation center and pilots communication. Transmission is made on a double side band (DSB) amplitude modulation (AM) carrier. The frequencies are selected within the band 118 – 137 MHz.

[TBC: spectrum allocations]

8.33 kHz

8.33 kHz channel spacing was recognized as the only medium term solution to alleviate the European congestion in VHF communication band and was implemented 7th October 99 within the FIR/UIR of the core Europe (Austria, Belgium, France, Germany, Luxembourg, Netherlands, Switzerland). Carriage of 8.33 kHz channel spacing R/T equipment is then mandatory for all aircraft when operating or capable of operating above FL 245. Mandatory carriage of 8.33 will be extended to additional airspace over FL245 of 21 States as from October 2002Projects for horizontal (ie outside core area) and vertical (ie above FL 195) exist8.33 usage below FL 245 is currently considered in Europe.

8.33 supports voice communications between controllers and pilots.

The frequencies are selected within the band 118 – 137 MHz

Note: in some regions of the World, aircraft are still flying with 50 kHz or even 100 kHz VHF radios.

[TBC: spectrum allocations]

HF SSB

HF SSB (single side band) is operated in the band 2.8 MHz - 22 MHz, which is allocated to the aeronautical mobile (route) service. This system supports voice communication exchanges in oceanic and remote regions.

[TBC: spectrum allocations]

HF Data Link

ICAO SARPs for HF data-link are applicable from 1999. HF data link uses bands between the 2.85 MHz - 22.00 MHz range. This system uses a bit-oriented air-ground protocol which conforms to the open system interconnection (OSI) model and is designed to function as a sub-network of the ATN. Also operating in ACARS mode

The data link appears to offer a practical means of data communications that could be utilized to backup or complement to satellite ata link. HF data-link can provide coverage at high latitudes, where satellites are unusable.

[TBC: spectrum allocations]

AMSS

In this part of the document only the 1st generation satellites system will be addressed. A number of types of satellite communications are in existence or proposed for implementation to support air-ground data link communications as one of their functions (satellite systems can support a very wide range of communications requirements). They are Geo Stationnary based (GEO) and operate inside the 1545/1555 – 1646.5/1656.5 MHz band. Most of these systems are proposed to operate on one of three main principles:

a) geo-stationary orbit satellite (GEOS);

b) medium earth orbit satellite (MEOS); and

c) low earth orbit satellite (LEOS).

ICAO SARPs for 1st generation AMSS are applicable from 1995With GEOs. Civil Aviation has lost its exclusive allocation but spectrum is still available in the L band. Voice and data channels to aircraft are available now from third party providers (mainly using INMARSAT satellites). Data may be ATN or ACARS compliant

VHF ACARS

Some data-link services use non ICAO standard systems (e.g. ACARS/ARINC 622 in the Pacific and ACARS/ARINC 623 in continental Europe). ACARS is based on thea 25 kHz VHF-DSB-AM system. It which was originally designed for AOC services. Since the introduction of protocols like ARINC 623, it has been increasingly used, for ATS communications in particular.

Note: ACARS extensions services are also provided exist on HF or AMSS (see above)

VDL Mode 2 Data link

ICAO SARPs and guidance material on this air-ground data-link are applicable from 1997.

VDL Mode 2 is an evolution from ACARS and uses a D8PSK modulation scheme to support improved data rate (31.5 kb/s). It supports data only and is designed to be ATN compliant, but can operate without the full ATN stack.

VDL Mode 2 subnetwork is not designed to support time critical applications. Due to the access mechanism (CSMA) it exhibits a non deterministic behavior and it cannot guarantee a required performance level in terms of transfer delay.

The frequencies are selected within the band 118 – 137 MHz

VDL Mode 3 Data link

At SP COM/OPS/95 Meeting, this system was accepted to replace the VHF DSB-AM systems in the long term, whereas the new 8.33 kHz channel spacing would be implemented in Europe. Mode 3 allows four 4.8 kb/s links for voice or data on a 25 kHz channel, using a time division multiple access principle (TDMA). The data capability is a constituent mobile subnetwork of the ATN. In addition, the VDL may provide non-ATN functions.

ICAO SARPs and guidance material were published (76th amendment of Annex 10) by November 2001. Planning criteria in the COM band (117.975 – 137 MHz) are not yet fully defined.

The frequencies are selected within the band 118 – 137 MHz

VDL Mode 4 Data link

The SP COM/OPS/95 requested the development of SARPs for data links to support navigation and surveillance elements of CNS/ATM applications. Data links, which were considered by ICAO at that time, were SSR Mode S extended squitter and VDL Mode 4.

VHF DL Mode 4 is based on a self organized time division multiple access principle (STDMA), using a 19.2 kb/s GFSK modulation scheme. Point-to-point and Broadcast data surveillance applications are supported by non-ATN specific services, and point-to-point data surveillance applications are supported both as a subnetwork ofby ATN and as non-ATN specific services.

ICAO SARPs and guidance material were published (76th amendment of Annex 10) by November 2001, and Mode 4 has been approved for surveillance applications. Planning criteria in the COM (118 – 137 MHz) and NAV (108 MHz- 117.975 MHz) bands are not yet fully defined. Mode 4 would need two global signaling channels and several local channels.

SSR Mode S

ICAO SARPs are have been available since 1996. SSR Mode S is the next-generation ground-based radar surveillance system. In addition to its SSR Mode A/C and Mode S surveillance capability, Mode S also supports full data link transactions and is defined as an aeronautical telecommunication network (ATN)-compliant sub-network.

Mode S Elementary Surveillance enables the use of the unique 24 bit aircraft address for selective interrogation and to acquire the Aircraft Identity (Call Sign or Registration mark) from the aircraft.

Mode S uses selective interrogation to communicate with aircraft, hence eliminating several problems found with the existing Mode A/C surveillance. However, Mode S is fully compatible with Mode A/C and supports ACAS which uses the same frequencies (1 030 MHz and 1 090 MHz).

Extended squitter is an addition to the Mode S system designed to support ADS-B and SMGCS which will also allow further enhancements to ACAS. Extended squitter consists of a set of broadcast messages that provide information on the aircraft position, velocity, identification... It uses the same format as the current Mode S data link and operates on the Mode S down-link frequency.

MLS

MLS provides precision approach guidance for all categories of landings. The MLS data link uses differential phase shift keying (DPSK) modulation and cyclic redundancy checking (CRC) to ensure integrity and performance. MLS operates in the 5 030 MHz - 5 091 MHz band with 200 channels spaced on 300 kHz centre frequencies and 200 channels reserved for future use in the 5 091 MHz - 5 150 MHz band.

[TBC: spectrum allocations]

GBAS Data Link

The data link element of GBAS shall be operated in VHF, using a differential 8-phase shift keying (D8PSK) modulation scheme.

The portion of the spectrum that has been considered for the purposes of VHF GBAS is the navigation band currently occupied by the ILS and VOR (108 MHz - 117.975 MHz). It is proposed that the D8PSK data link be designed such that it can fit on 25 kHz channel spacing, allowing the GBAS to be slotted between VOR allocations. The GBAS uses the same D8PSK modulation scheme as VDL Mode 2 yet only operates in the ground data broadcast mode.

[TBC: spectrum allocations]

Functional description matrices

Technical characteristics:

| |VHF 25 kHz and 8.33 |HF SSB |HF Data Link |AMSS |

| |kHz DSB-AM | | | |

|VHF 25 kHz and 8.33 |Communication |All current types |All current types |All current types |

|kHz DSB-AM | | | | |

|HF SSB |Communication |All current types |All current types |All current types |

|HF Data Link |Communication |CPDLC |D-FIS, ADS-C, possibly|Yes |

| | | |DAP | |

|AMSS |Communication |CPDLC |D-FIS, ADS-C, possibly|Yes |

| | | |DAP | |

|VHF Mode 2 Data Link |Communication |CPDLC |D-FIS, ADS-C, possibly|Yes |

| | | |DAP | |

|VHF Mode 3 Data Link |Communication |CPDLC |D-FIS, ADS-C, possibly|No |

| | | |DAP | |

|VHF Mode 4 Data Link |Surveillance |SMGCS | | |

|SSR Mode S |Communication |CPDLC, SMGCS |Enhanced surveillance,|No |

| |Surveillance | |D-FIS (possible but | |

| | | |not anticipated), | |

| | | |ACAS, ADS-B/C, TIS | |

|MLS |Navigation |Not under |Not under |Not under |

| | |consideration |consideration |consideration |

|GBAS |Navigation |Not under |Not under |Not under |

| | |consideration |consideration |consideration |

Phase of movement:

The table below relates to the use of the various technologies for the different phases of flight, not taking account of possible multi-path, shadowing or interference problems.

| |Oceanic |Continental en route |Terminal |Tower |Airport surface |

|VHF 25 kHz and 8.33 |Limited to line of |Limited to line of |Limited to line of |Yes |Yes |

|kHz DSB-AM |sight |sight |sight | | |

|HF SSB |Yes |Yes |No |No |No |

|HF Data Link |Yes |Yes |No |No |No |

|AMSS |Yes (except poles) |Yes |Yes |Yes |Yes |

|VHF Mode 2 Data Link |Limited to line of |Limited to line of |Limited to line of |Yes |Yes |

| |sight |sight > | | |

|VHF Mode 3 Data Link |Limited to line of |Limited to line of |Limited to line of |Yes |Yes |

| |sight |sight> | | |

|VHF Mode 4 Data Link |Limited to line of |Limited to line of |Limited to line of |Yes |Yes |

| |sight |sight> | | |

|SSR Mode S |Limited to line of |Limited to line of |Limited to line of |Yes |Yes |

| |sight |sight |sight | | |

|MLS |No |No |No |Yes |Yes |

|GBAS |No |No |Yes |Yes |Yes |

Status of ongoing activities

This section provides information on activities related to the systems which are not yet operational. The table below presents a high level synthesis of the current status of the different technologies. For the MLS and GBAS data links, no specific data-link communication application has been defined yet, and no activity is carried out in this field.

HF Data Link

[TBD]

VHF Mode 2 Data Link

Petal II

PETAL II (Preliminary Eurocontrol Test of Air/ground data Link) has built on PETAL to develop an operational environment for CPDLC, including the HMI for both pilots and controllers.

By conducting multi-aircraft a/g data-link operational trials during routine ATC operations the PETAL II objectives were to:

- validate operational concepts, requirements and procedures for air/ground data-link;

- obtaining data on the operational benefits, requirements, human factors, procedures and problems associated with using air/ground data-link in busy continental European airspace.

Eurocontrol Petal II Extension project has operated four aircraft equipped with ATN on top of Mode 2 from May 2001, in order to evaluate potential operational issues. PETAL program is now included within Link2000+ program

AFAS

The European AFAS program is the first step in achieving the airborne components of the functionality set out in the ECAC ATM 2000+ baseline.

It defines three new operational services: Pre-flight Trajectory Co-ordination, 4D flight trajectory, and re-planning of 4D trajectory.

The AFAS concept includes:

- data link communications using Mode 2, ATN, CPDLC, ADS and FIS applications;

- surveillance using air/ground data link communications.

Through coordination with MITRE, services provided as part of AFAS will be distributed by phase (preflight, flight). Validation will be performed through fast-time simulations. The Program is expected to last until 2003.

VHF Mode 3 Data Link

[TBD]

VHF Mode 4 Data Link

NUP

MA-AFAS

The European MA-AFAS program addresses areas such as:

-evaluation of airborne 4D flight path generation for integration with ground based flight path planning,

- integration of airborne taxiway map and data linked clearances,

- validation of ADS-B with airborne display of traffic (CDTI) and airborne separation assurance algorithms (ASAS).

The MA-AFAS avionics package will be validated using both light simulators and trials on experimental aircraft, with simulated and operational ATC centers in shadow mode. This validation will use real data link communication, representative navigation facilities and surveillance functions including ADS-B (using VDL Mode 4) to provide traffic information. Final results are expected by 2007.

MFF

MEDUP

SSR Mode S

[TBD]

|Systems / Status |Operational |Pre-operational |Validation |Trials |Research |

|VHF 25 kHz and 8.33 kHz |25KWorld-wide | | | | |

|DSB-AM |8.33 Europe | | | | |

|HF SSB |World-wide | | | | |

|HF Data Link |AOC only |Ongoing for ATS in North |Ongoing for ATS in North | | |

| | |Atlantic |Atlantic | | |

|AMSS |South Pacific |North Atlantic | | | |

|VHF Mode 2 Data Link |No (1) |Ongoing in Europe |Ongoing in Europe | | |

|VHF Mode 3 Data Link |No |No |Ongoing in the US | | |

|VHF Mode 4 Data Link |No |Ongoing in Europe |Ongoing in Europe | | |

|SSR Mode S |No (1) |Ongoing in Europe |Mode S system complete, | | |

| | | |Mode S sub-network ongoing| | |

|MLS |None defined |None defined |None defined |None defined |None defined |

|GBAS |None defined |None defined |None defined |None defined |None defined |

(1) operational systems are being purchasedfor installation by 2002 and onwards

Programs and future activities

Implementation plans

VHF Mode 2 Data Link

In 1999, industry proposed a two step implementation of VDL Mode 2 services. In a first step the existing ACARS messages will be transmitted using the minimum of VDL Mode 2 (ACARS over AVLC, AOA). This step foresees the deployment of a VDL 2 air-ground segment limited to the functions required for delivering higher performance to unchanged ACARS applications. Service Providers are committed to start AOA operation both in Europe and in the United States.

As the second step, full Mode 2 capabilities services will be implemented. Furthermore both EUROCONTROL and FAA have set up respective projects (Link2000+, Build1 and 1A) that co-ordinate the deployment of ATS data-link services based on Mode 2.

In the frame of the US NEXCOM Program, alternatives which would include Mode 2 and Mode 3 or analog voice are being assessed (see next section). According to the current NEXCOM implementation path, it is not anticipated that Mode 2 will be decommissioned before 2015.

According to the Eurocontrol communication systems roadmap (AMCP-WGC/1-WP16), data services will be supported by Mode 2. As a first phase, ATIS and DCL applications will be based on ACARS and on Mode 2 AOA. It is expected that ATN Mode 2 will be in full operation around 20102007.

VHF Mode 3 Data Link

The implementation of VDL Mode 3 in the United States will be accomplished through the Next Generation Communications Program (NEXCOM). The FAA established the NEXCOM Program in 1998, to address NAS future domestic air/ground communications for voice and data.

Implementation will occur in two phases (AMCP-WGM/3-WP26):

- Phase I: the design, demonstration and validation phase, will include the development of a preliminary design of the system. The Engineering Development Model (EDM) will be demonstrated and validated to show compliance with a group of minimum threshold requirements that are a subset of the system requirements.

- Phase II of the NEXCOM program is the Full Scale Development of the system. The final NEXCOM system production design will be completed, the operational system will be developed, tested, produced and fully deployed.

FAA will demonstrate a “certifiable” VDL-3 voice system and an “interoperable” data system by 2004 (AMCP-WGM/3-WP25). Plans anticipate implementation of operational digital voice between 2005 and 2007by 2009. Data capabilities are expected to be implemented between 2007 and 2015beyond 2009.

Recently, the NEXCOM Aviation Rulemaking Committee (NARC) recommended to investigate the following options, and to develop en alternative plan if Mode 3 proves untimely (AMCP-WGM/3-WP25):

- Mode 3 for voice and data,

- Mode 3 for voice and Mode 2 for data,

- VHF 8.33 kHz DSB-AM for voice and Mode 2 for data.

In Europe, there are some concerns on the feasibility of transitioning to a Mode 3 environment, especially for voice, due to the heavy congestion of the VHF COM band and the benefit of implementing 8.33 kHz. Potential use of VDL Mode 3 in Europe needs further investigation.

VHF Mode 4 Data Link

Issues raised

VHF 25 kHz and 8.33 kHz DSB-AM

Technical Constraints

Restricted coverage, particularly at low level

Already congested frequency spectrum

HF SSB

Technical Constraints

Availability of frequencies

Poor voice quality

Very sensitive to solar, atmospheric conditions and interference

HF Data Link

Technical Constraints

Availability of frequencies

Transfer delays

Low bit rate

Very sensitive to solar and atmospheric conditions

AMSS

Technical Constraints

Available bandwidth still existing but limited

Connection establishment time

Transit delay time(GEOs)

No hot stand-by satellite(current AMSS1)

Implementation Constraints

High cost of airborne fit and high cost of operation for 1st generation AMSS

Shared use of satellite links for different communication service types

VHF Data Links (Mode 2, 3 and 4)

Technical Constraints

Restricted coverage, particularly at low level

Implementation Constraints

Lack of available VHF channels

Proliferation of standards in VHF data-links

SSR Mode S

Technical Constraints

Restricted coverage, particularly at low level

6.0 The problem statement

Comments to: kors@

Step capacity in communication, steady traffic growth. Com should not become the restrictive growth factor. However to plan capacity over a twenty five year span becomes difficult and also costly in a step scenario. Looking at evolutionary system growth or transitional aspect other systems (likely also other frequency bands due to congestion)

7.0 Determining the future Need

Comments to: kors@

The perceived need

It is very difficult to determine the communication future needs, as the operational concept in which communication is the enabler hasn’t yet been defined. The lack of a clear operational concept will have more bearing on the planning for the mobile than on the fixed communications. The determination of the future fixed communication is mainly a matter of capacity planning for a specific time period.

Until such time when the Requirement Communication Performance (RCP) concept is translated into real Communication Performance Parameters for the various ATC regimes the candidate air-ground and air-air data-link can only be validated against each other but not against hard operational requirements.

The introduction of concepts such as free flight and self separation assurance might even require a different approach to the RCP as the availability and integrity requirement for the systems are very different from a traditional ATC regime. The decisions whether the responsibility for separation lies on the ground, in the air or a combination of the two will have a large bearing on the selection from alternatives and the associated costs for the supporting infrastructure.

In Europe, from a communication point of view, the ATM concept as well as the airspace structure which would be in operation by 2015 are described in the annex x

Notwithstanding the previous mentioned uncertainties, the industry can’t afford to wait in planing for the air-ground infrastructure to ensure that the foreseen ATM services can be timely accommodated. To facilitate the works the requirements have been divided in two categories. Whilst not being fully mutual exclusive a distinction has been made between operational communication requirements and communication service requirements.

Operational communication requirements are those requirements seen from a user perspective. The communication service requirements are looked at from a technical system perspective how these requirements can be met..

The Optimum Infrastructure.

The optimum aeronautical communication infrastructure would be a solely data environment. However, under the present operating conditions voice will still remain an important element in the ATS services. At this stage of development it is uncertain to which extent the voice communication can be integrated in the data communication infrastructure. It is likely that in the near future the ground voice communication could be conducting within the to be deployed ATN data packet network, with respect to the air ground systems the feasibility is not certain.

The integration on the ground of all aeronautical voice and data communication within one network would enable significant cost savings. Further cost saving could be achieved by integrating all aeronautical communication services through a service broker and sharing facilities with non-aviation communications. In order to realize these costs saving the traditional role of ATS providers as communication provider should be eliminated. It might be possible to achieve the benefits at an early stage by pursuing a fast transfer from the present AFTN to an ATN framework within the appropriate institutional framework.

The optimum air-ground infrastructure would be a single global operational system meeting the most stringent operational requirements. However spectrum availability, different traffic densities and geographic circumstances might require the use of different or alternate systems. Furthermore, the time an improved communication infrastructure is required will vary from Region to Region and country to country.

8.0 Operational Communication Requirements

Introduction

Operating Concept

The operating concept for a communication service is dependent on the operating concepts for operating aircraft and managing air traffic, which use the communication services. At one extreme, VFR flight from an uncontrolled airfield might be accomplished with no communications between the aircraft and any ground agency. At the other extreme, an airline flight in high-density airspace will require continual communication between the aircraft and air traffic control and also with the airline operations center.

In addition to the safety communications services required to direct flight operations safety and regularity, the modern passenger desires the capability to communicate with the ground using telephone, internet data connection, and timely news feeds.

The range of operating concept is a continuum in two dimensions, ranging from the very simple to the very complex and continually changing with time, as both the requirements and the technical capability to meet those requirements continue to evolve.

The accommodation of increasing air traffic will demand the introduction of new or improved services to maintain at least the level and safety. Furthermore, the security element will increasingly become an integral part of the aircraft operations.

Existing Communication Operating Concept

The operating concept of most interest is one supporting an aircraft operating in airline service because it requires a broad spectrum of communication services. The aircraft is flown IFR almost exclusively, requiring continual[3] radio contact with air traffic control. In addition, operating regularity requires that the aircraft is in continual contact with the airline operations center, as well as the airline operations center. Passenger communication services are limited to telephone communication during en route flight when the aircraft is equipped and flying in an area of coverage.

VHF Voice-operation

For domestic terrestrial en route and terminal operations, the primary communication service is VHF voice radio. The flight crew selects the operating frequency (channel), discovered either by looking in publications of by being told the frequency by a previous flight controller. VHF voice radio is operated on the channel as a form of collision sense, human listening multiple access (HLMA) protocol; that is, the pilot or controller listens to the channel, determines when the channel isavailable, then keys the microphone and states his message. A possible collision with another transmission is generally detected if the called party fails to respond in an appropriate way. If a suspected collision or other error is suspected, the message is repeated. The human operators are the "protocol engines" in this process, requiring attention and mental workload to queue the message, detect an openslot, transmit the message, and detect if the message is acknowledged. In addition, the flight crew must receive frequency change instructions, acknowledge the frequency change message, make the frequency change on the radio control panel, and make an initial call on the new channel.

One of the key characteristics of VHF voice is the fact that all radios tuned to a particular frequency can receive all transmissions made by other radios within radio line-of-sight. This "party line" effect allows all aircraft, which are typically all in a single air traffic control sector, to monitor the conversations and to anticipate air traffic instructions they will receive. The negative aspects of the "party line" are the increased workload monitoring these other conversations to detect when the transmission is for their aircraft as well as the potential for error, when an instruction is different from the anticipated instruction. To reduce the potential for errors a global standard phraseology for pilot-controller communications has been developed.

HF Voice operation

For oceanic and remote area en route operations, the voice communication service is often HF voice radio. Operation is similar to VHF voice radio operation except that HF propagation characteristics vary with time of day and various other conditions and are seldom as good as VHF. Therefore, the pilot and ground radio operator might be required to retransmit a message to compensate for not only transmission collision but also noisy and weak transmissions. At times, transmission is not feasible. It most cases this is cured by the pilot selecting another frequency from the family assigned to the HF ground communication station. . On the ground, the radio operator is sending and receiving messages as an agent for the air traffic controllers. This division of labor allows the radio operator to concentrate on the task of monitoring and operating the radio and allows the controller to work with preformatted data messages. In the aircraft, the task of monitoring the HF radio is somewhat relieved by use of the selective calling (SELCAL) system, which is a tone pair sent from the ground radio to the aircraft, which in turn alerts the flight crew to the fact that they are being called. Therefore, the flight crew is not required to listen to continuous white noise in their headsets between calls.

During the time the flight crew is actively monitoring the channel, the "party line" effect described for VHF voice radio also applies to HF voice.

Satellite Voice operation

Satellite voice communications is available in oceanic and remote en route areas, if the air traffic control agency and the aircraft are both suitably equipped. Satellite voice modeled after telephone voice circuits. The originator of a call must know, or have stored in a database, the called party's telephone number. When the call is placed, the called party is alerted and completes the circuit. The conversation is full duplex, allowing both parties to speak and be heard simultaneously. The conversation is also private, so the benefits of a "party line" are not available to satellite communications. Because of the financial model, which causes one of the parties (typically the calling party) to be charged for the time of the connection, the conversation is necessarily brief and then the parties are disconnected until a subsequent call is made. (To prevent discussion on financial models might it be better to state something as follows: The conversation is kept brief to preserve precious radio spectrum and satellite power.

Current satellite service is provided by the Inmarsat constellation of geostationary satellites. These satellites provide coverage as much as 80 degrees north and south of the equator at the longitude of the satellites — somewhat less than that between the satellites.

VHF Data operation

VHF Data communications provides for transmission of short (256 character) strings of numeric and upper-case alphanumeric characters, plus a limited set of special characters, over the Aircraft Communications Addressing and Reporting System (ACARS). ACARS uses one of the VHF voice radios on the aircraft, tuning it to an assigned frequency. ACARS provides for the automatic reporting of aircraft state (e.g., out, off, on, and in times) as well various airline-specified reports. ACARS also provides a method for the flight crew to send and receive messages, with message selection and/or entry using a dedicated or multi-purpose control display unit (MCDU). A cockpit printer also allows the flight crew to retain received messages for later use.

At the encouragement of the airlines, ATS service providers have begun using ACARS to communicate air traffic services with the aircraft. Among the early ATS messages, the most valuable have been pre-departure clearance (PDC/DCL), digital ATIS, and oceanic waypoint position reports. The standards for these messages have been evolving, causing incompatibility between aircraft implementations and some of the ATS implementations. The most current standards for ATS messages over ACARS are found in ARINC 623.

Because of the limitations of the character-oriented messages, ACARS is not inherently capable of sending bit-oriented messages, which are generally much more efficient. Since bit-oriented communication paths have not been available, a transition step was taken, allowing conversion of bit-oriented messages to allow them to be transmitted over character-oriented ACARS. The conversion is documented in ARINC 622 and is called ACARS Convergence Function (ACF). Using ACF as a base, the bit-oriented FANS-1/A message set can be communicated between the aircraft and air traffic control through the communication service provider central processing facility .

Direct bit-oriented VHF data communications have been standardized by ICAO in VHF Digital Link Mode 2 (VDL-2) and is being implemented on a limit set of aircraft and ground stations. VDL-2 is an improvement over VHF ACARS in that the higher bit rate it improves the efficiency and quality of the network and VDL-2 can directly support bit-oriented communications. A convergence function called ACARS over AVLC (AOA) has been developed to provide transition for character-oriented ACARS message.

HF Data operation

HF data communication uses the aircraft HF radio to communicate digital data with a ground station. In general, HF data is more able to communicate during times of poor propagation than is HF voice. This is due to extensive error detection and correction algorithms implemented in the protocol and because the radio can automatically search for frequencies and ground stations with better propagation characteristics. HF data is slow relative even to VHF ACARS, providing an average transfer delay of 75 seconds and a 95th percentile delay of 200 seconds. Current HF data link installations are capable of carrying character-oriented ACARS messages. An upgrade has been defined that will allow conveyance of bit-oriented data messages.

HF ground stations are available at numerous locations around the world, allowing for connectivity wherever the aircraft is in the world. HF propagation characteristics are such that the range from the aircraft to the ground station is not restricted to line-of-sight. Since data can be routed to the aircraft from a terminal anywhere in the world (and vice versa), selection of an HF ground station is independent of the ATC ground control facility with which the aircraft is communicating. Ground station selection is based on quality of the connection, not the ground destination of the message.

Satellite Data operation

Satellite data uses the same avionics as satellite voice. Like HF data, the current installations can carry character-oriented ACARS messages and the standards are defined for future bit-oriented service. Like HF and VHF data link, the aircraft is assigned to a satellite that will provide the best service and the data message is routed on the ground to the correct destination. Average transfer delay is typically less than 30 seconds and 95% of all messages are delivered within 60 seconds.

New Communication Operating Concept

The operating concept for future communications will become increasingly more dependent on data communications but still requires voice communications. Digital modulation of radio transmissions and enhanced protocols will be implemented in order to improve communication integrity and capacity. Channel management will be increasingly automated to reduce pilot and controller workload and to more efficiently use allocated spectrum. Automatic routing over the most appropriate radio system, for both voice and data, will ensure continuity of service while minimizing required pilot and controller interaction with system selection and frequency selection.

Data vs. Voice Communications

The airlines have found, during the more than 20 years since they began using ACARS, that they require less operational voice communications as they grow increasingly dependent on data communications. Further, as the airlines have integrated data communication with the aircraft into the business of operating the airline, they have found more and more uses for data communication to improve the effectiveness and efficiency of airline operation. Many business aircraft operators have also integrated data communications into their operations. In addition to aircraft state reports to the dispatchers, the airlines are increasingly dependent on maintenance reports from the aircraft prior to landing and a wide variety of other aircraft status reports. The airlines rely on data uplinks for flight plan loading, weight and balance calculations, and passenger manifest information. In addition, the airlines have used ACARS for information that is properly air traffic services, such as weather observations and briefings, ATIS, and pre-departure clearances. All of these services have offloaded voice services of either the airline or air traffic control.

Air Traffic Services will experience a similar reduction of voice communications as data communication becomes more common. Aircraft access to digital flight information services, such as weather, NOTAM's, ATIS, and special use airspace will reduce the need for two-way voice traffic and the resulting workload and error and may even allow the reduction of some broadcast services. As performance issues are overcome, CPDLC will allow improved air traffic control with significantly less voice traffic. Low time criticality messages, such as departure clearances, taxi clearances, barometer settings and radio frequency changeswill provide significant reduction in voice communications (as they already are doing via ACARS). More time-critical messages between the aircraft and the air traffic system will provide reduced workload and errors and also increase the availability the sector voice communications channel when needed. ( GA dream?).

Digital Modulation

Radio transmissions have been traditionally modulated using analog signals. VHF Communication radio uses double-sideband amplitude modulation (DSB-AM). HF radio uses single-sideband (SSB), with the upper sideband (USB) chosen as the aeronautical standard.

Modern radio communication systems have been evolving from analog to digital modulation in order to optimize use of available bandwidth, allow processing to minimize the effects of noisy signal and variations in signal strength, and allow integration of voice and data over a common medium.

Channel Management

The present technology in the mobile telecommunication has the user completely relieved from the channel management and frequency selection. Satellite communication was the first system taking advantage of this feature. With the introduction of ground based dynamic channel allocation algorithms the pilot and controller communication workload will not only be eliminated but will increase the overall channel availability and enables the various communication systems to be intregrated into one virtual system.

Message Routing

Due to the high Quality standards for safety voice it is unlikely that air-ground voice communication can be supported by a packetized data service in the short term, requiring the need for direct speech circuits. This leaves two ways of message routing for data i.e. through packet data network or over the established circuits for voice. The main tradeoff between these two alternatives is speed versus availability.

Required Communication Performance

The ICAO OPLINK panel has developed a Required Communication Performance (RCP) concept, parallel to the previously developed Required Navigation Performance (RNP) concept. The intent is to establish a metric for communication performance that is related to how the communication medium is to be used and independent of the technology required to achieve that performance. The RCP, as currently defined, includes delays attributed to not only the communication link but also the human-machine interface and the human delay involved with decision-making and response. As a result, RCP delay cannot be used as a useful requirement for defining system communication link performance.

Although the RCP definition mentions the performance parameters of integrity and availability, the required values for these parameters have not been established nor applied specifically to the communications link. Therefore, the following quality descriptions are presented for consideration in the establishment of communication requirements.

Quality of Service

Quality of service for any air/ground communication link may be expressed in three terms — delay, integrity, and availability. A minimum quality of service needs to be specified for each type of service and operational scenario. >

• For instance, two-way voice or data communication between the cockpit crew and an air traffic controller in high-density airspace requires minimum delay, high integrity, and high availability.

• On the other hand, a data link request for predicted winds aloft while flying in low-density airspace might be adequately supported by a link service that had relatively long delays, less integrity, and lower availability.

• A voice service generally requires a relatively short delay and relatively high integrity and availability, regardless of the data being communicated, because the human operators at the ends of the voice service need to communicate information without the excessive workload inherent in long delays, a noisy link or an unreliable connection.

• Simplex voice, whether two-way or broadcast, can withstand more delay than a duplex telephone-like service, provided the delays don't cause access problems among multiple users (e.g., inadvertent simultaneous transmission).

Since quality of service is often strongly correlated with cost of service, over-specifying quality of service for a specific type of function and operational scenario will cause increased costs and may prevent the service from being implemented.

Although the terms of reference for ICAO relate only to services to support operational safety and regularity, a consistent set of requirements for all air/ground communications, including passenger and administrative services, is useful to enable integrated solutions where possible. Passenger and administrative services also have quality of service requirements. Instead of being based on a safety analysis, passenger and administrative quality of service are justified by user satisfaction and efficient operation. A passenger or cabin crew telephone connection would require minimal delay and moderate integrity (providing a voice quality nearly equivalent of land-based long distance service); non-availability during portions of the flight or ground operations might be acceptable. A passenger or cabin crew e-mail, on the other hand, could probably accept a relatively large delay and limited availability but would require relatively high integrity

Users

Users are located both on the aircraft and on the ground. The cockpit crew and air traffic controller are the first, and perhaps the most critical, pair of users normally considered. Other pairs of correspondents might include:

• cockpit crew and operations center,

• cockpit crew and ground weather database,

• ground weather database and airborne sensors,

• ground and airborne databases,

• cockpit crew and airport database,

• cabin crew and gate assignment database,

• cabin crew and catering service,

• passenger and selected e-mail server,

• passenger and selected ground telephone, and

• airborne web server and ground web server.

As illustrated in the above list of examples, not all users are people, either in the aircraft or on the ground. Allowing a human to request information from a database might more efficiently provide much of the information that must flow today through human operators. Automatic synchronization of ground and airborne databases (e.g., weather, flight plan, flight schedule, special use airspace, popular web sites) provides a way to use off-peak communication capacity to reduce user-perceived delay during subsequent delay-sensitive operations.

Integrate ADS-B communication into the paper.

User Information

The true users' requirement is to be able to convey information accurately, quickly, with a minimum amount of workload and other overhead function. Whether that information is a simple "Wilco" response to an ATC clearance, a complex graphic weather product to be processed by a flight crew member or a flight management computer, or a synoptic data dump from an onboard maintenance computer to an airline analysis computer, the communication link should provide a quality of service appropriate for the requirements of the function without imposing undue constraints or distortions. The communication link should be able to handle not only functions used during current operations but also new functions developed for operations of the future.

Users share information in a number of ways. Two-way analog voice is the traditional, and most widely used, information sharing method. Broadcast voice is used for some weather products and for ATIS. Digital two-way data link has been used for aircraft operational data delivery (for both airline and corporate operations) and has recently been used for some air traffic services. Broadcast data transmission is being tested for ADS, for traffic information, and for weather.

Some of these information-sharing methods are marginally effective but, until recently, were the only methods available. A prime example is the use of repetitive audio broadcast for ATIS. A human operator must read weather and related information from a screen or printout, generate a script for an hourly ATIS message, read that message into a recorder, and enable the recording to be broadcast continually on a VHF Comm. or VOR voice channel. A flight crewmember must tune a receiver once within radio range of a ground transmitter, listen to the broadcast, and transcribe the information into written form where it may be referenced by all of the crewmembers. This process is workload-intensive at both ends, continually uses a valuable radio channel for information that typically changes only once an hour, has a high probability of transcription errors at both ends, and provides a cumbersome method of ensuring that last-minute information is provided.

A key concern when transitioning from operations using two-way voice to operations using addressed messages, either voice or data, is the loss of the "party line". Pilots gain a certain amount of situational awareness by listening to transmissions to and from other aircraft. For instance, a pilot listening to the dialog with aircraft ahead of him on the Approach Control frequency can anticipate future speed changes, altitude clearances, etc. Also, comments about windshear, turbulence, icing, and other weather phenomena can be instantly shared among all aircraft sharing a frequency, with no additional workload by any of the participants. The negative aspects of "party line" include the fact that a pilot may anticipate a clearance and fail to notice that his clearance is not the same as that given to the previous aircraft. Another problem with "party line" is the workload involved in listening to the radio traffic and filtering the important from the unimportant. Part of this workload includes accurately hearing transmissions intended for the subject aircraft and the hazards involved with either inadvertently responding to a clearance meant for another or failing to respond to a clearance meant for the subject aircraft.

Possibly something on timing of information and way of obtaining i.e interrogated a data base from the air to get weather , METAR etc and the need to receive unsolicited warning such as alert i.e Vulcanic ash turbulence etc

Human - Machine Requirements

The new technology has the potential to simplify significantly the required human machine interface for voice communication through a signal push to talk switch and possibly a panel to select the party to be address and the system status. For data communication benefits should be taken from the vast developments in the 3G technology to simplify the user.

Capacity

Calculating the required capacity for future air/ground communications is a complex operation. The calculation must consider, inter alia,

1. the number of aircraft;

2. aircraft distribution in space;

3. the operational concept:

4. number of aircraft per sectorin coverage (channel),

5. number of transmissions per minute,

6. amount of information per transmission, and

7. efficiency of transmission;

8. radio channel characteristics:

9. channel bandwidth, and

10. geographic coverage per channel (i.e., channel re-use).

The number of aircraft and their distribution are assumed to be beyond the control of air traffic or communications experts. The demand of additional flights and the density of those flights will continue to place additional demands on air traffic control. The operational concept for air traffic control provides the biggest leverage for improved operations. Improved efficiency of operations and of communications can allow existing radio channels to be used in a more efficient manner, allowing more aircraft to communicate with existing radio resources. The work of AMCP — to develop additional radio channels and to specify efficient use of those channels — is a necessary activity, but not the only means, for providing the necessary communication for air traffic safety and efficiency.

Technologies

The operational requirements for aeronautical communications should not specify technologies but should specify capacity and quality of service using technology-independent terminology. Due to imperfect technologyphysical limits, no known solution perfectly meets all requirements. Therefore, engineering judgment must be applied to judge technologies and weigh the various requirements to iteratively approach the technologies that most nearly meet all of the requirements.

9.0 Communication Service Requirements

Comments to: delrieu_alain@dna.dgac.fr

Introduction:

This chapter defines the technical requirements applicable to an Aeronautical Communication System (ACS) designed and operated for the provision of the communications to support to flight safety and regularity .

This chapter is complementary to the preceding chapter stating the Operational Communication Requirements, and accordingly its scope is restricted to the technical component of the end-to-end system chain linking ground systems and airborne systems to support human to human, human to machine and machine to machine communications.

It contains the techniques how these operational requirements can be met.

Communication service characteristics

Communication precedence, priority and access

RF Characteristics

Emissions

Signal Acquisition and tracking

Communication loading

Communication acknowledgement requirements for voice and data

Voice communication set-up and processing delay

Packetized data transmission

ATN Compatibility and standardized voice interfaces

10.0 Future alternatives

Comments to: philippe.renaud@eurocontrol.be

INTRODUCTION

As described in the section “Problem Statement”, the systems currently in operation or close to be in operation have several limitations. These limitations are mainly due to the saturation of the band where they operate (the VHF band) and to a more limited extend to their design based on technologies that does not provide the best efficiency regarding the use of spectrum. Another limitation is coming from the non-adaptation of the systems to the phases of flight or to the topology of service to be supported

To sustain the traffic increase (addition or re-arrangement of sectors), introduction of new concepts and corresponding communication services enabling for example more co-operation between the airborne side and the ground side, the telecommunication infrastructure needs to evolve.

In the future, the telecommunication for the ATS will be supported by an infrastructure that will be composed of different systems. Some of the systems described in the “Present situation“ section will still be present for a long time but would progressively be reallocated to specific services and/or to specific areas. New systems will progressively be introduced in the architecture to complement or even replace the current systems for some of their functions. These new systems (assuming airborne integration and migration issues are solved) are expected to be adapted to specific services and areas. In most of the cases, products developed by the telecommunication industry would be considered as potential candidates.

Several scenarios related to the most probable options can be identified, these scenarios are addressed in the section “scenarios”. However, before describing these scenarios, it is essential to identify the potential systems that could be introduced in the infrastructure and their main characteristics.

SYSTEMS TO BE INTRODUCED IN THE FUTURE COMMUNICATION ARCHITECTURE

The systems which could be integrated in the future mobile communication architecture, replacing or complementing the systems identified in the section “present situation”, are listed below with their main characteristics:

|Type |Services capability|Range |Topology (for data)|Data QOS |Throughput (4) |Operational usage |Band |Remarks |

| | |(1) |(2) |capability | | | | |

| | | | |(3) | | | | |

|VDL M 4 |Surveillance, ATN |Medium |Pt-to-pt & |D |Low |2008-2010 |108-137 MHz | |

| |data, & FIS | |Broadcast (A/A, | | | | | |

| | | |A/G, G/A) | | | | | |

|UAT |Surveillance & FIS |Medium |Broadcast (A/A, |D |Medium |2010-2012 |~960 MHz | |

| | | |A/G, G/A) | | | | | |

|Gate Link |No safety Data |Very Short |Pt-to-pt |P |High |2008-2012 |2.4 GHz | |

| |oriented | | | | | |5 GHz | |

| | | | | | | |ISM | |

|New satellite |Voice, ATN data, |Long |Pt-to-pt & |G |Medium |2010-2012 |L + C | |

|Generation |Data specific | |Broadcast | | | | | |

| |services | | | | | | | |

|Wideband (CDMA) |Not defined (No |Short |Pt-to-pt | |High |2010-2015 |C or other |Derived from 3G |

| |restriction | | | | | |appropriate band |technology |

| |identified) | | | | | | | |

It has to be noted that one current concept, already presented to AMCP and known as ETDMA, has not been integrated in the previous table as a candidate system and not mentioned explicitly in the considered scenarios. Indeed, the ETDMA is a concept to warranty a Quality of Service Level and not a system by itself. As such the ETDMA concept would be integrated in the design of new systems (such Wideband-based).

(1): Very Short: few 100 m

Short: up to few 10 miles

Medium: few 100 miles

Long: more than few 100 miles

(2): Pt-to-pt: Point-to-point

A/A: Air-to-Air

A/G: Air-to-Ground

G/A: Ground–to-Air

(3): P: Probabilistic i.e. no guaranty of access time or transit time

D: Guaranty of transit time and access time if the required QOS level is available

G: Mechanisms implemented to Ensure QOS

(4): Low: up to few kb/s per users

Medium: few 100 kb/s per users

High: up to few Mb/s per users

POINTS/CONSTRAINTS TO BE CONSIDERED IN A FUTURE COMMUNICATION ARCHITECTURE

This evolution has to be assessed considering the following aspects:

System adaptation: Due to the characteristics of their design and of the spectrum where they operate, communication systems could be more adapted to specific services and/or to range of operation (e.g. a satellite-based system is adapted to oceanic region due to the absence of ground infrastructure, a system based on wide band technology in C band, able to provide high bandwidth, is more suited than a VHF system in the vicinity of the airports where large traffic is expected).

System time of life: Considering the investment already done, the time required to decide to decommission systems currently used and the time required to proceed to systems decommission (i.e. transition period), the systems identified in the “Present situation” section will be still in operation beyond 2010 and could eventually stay for a longer time.

Industrial products: New generations of systems developed by the telecommunication industry (e.g. land mobile or satellite mobile), could be beneficially adapted to the aviation needs, considering their performances and their costs due to mass effect, and therefore could be integrated in the infrastructure.

Growth capabilities: With the current uncertainty for the future ATS needs, a future communication infrastructure needs to incorporate systems that are able to accommodate not-well-defined services or traffic volumes.

11.0 Scenarios

Comments to: philippe.renaud@eurocontrol.be

This section identifies potential scenarios for the future communication infrastructure trying to trade off the investment already done, the adaptation of the systems to the services and topologies.

The proposed scenarios are hereinafter illustrated by a temporal diagram describing how the infrastructure would evolve in the next 15 years. The diagrams are followed by a short description of these scenarios, the advantage and drawback identified as well as the issues which need to be further investigated before any conclusion could be drawn and which will help discussion to consider the respective merits of each scenario.

The scenario description is limited to high level considerations without going down in any details.

All scenarios assumed implementation ADS-B. This assumption needs to be confirmed.

The number of scenarios has been limited to a minimum. However, some variants could be added, by replacing in some scenarios one system by another.

It has to be highlighted that a scenario will be viable only if the migration from the current infrastructure to the next infrastructure is feasible without identified hard points. This is especially true considering that, during the overlapping period (which could last a while), systems (the system being withdrawn and the new system) have to be simultaneously operated with the consequence on spectrum availability for both especially if they operate in the same band.

Another important aspect for the viability of a scenario is the economical aspect that needs to be investigated and convincing.

SCENARIO 1

SCENARIO 1 DESCRIPTION

Scenario 1 is essentially based on systems operating in the VHF band for both communication and for surveillance services.

Voice communication will still be mainly provided using VHF 25 kHz DSB-AM and, in the congested regions, 8.33 kHz DSB-AM with an extension of the 8.33 mode in all airspace except those where VFR flights operate.

For relaxing the VHF load, new satellite generation system, to be introduced beyond 2010, will support voice services in very upper airspace (where VHF-based systems are not optimum in term of frequency allocation).

This new satellite generation system will also replace the current AMSS system, used currently in non-populated areas and in some region (such as ASIA). This system will also replace the HF/voice used in oceanic region providing better quality and shorter access time.

ADS-B services will be supported using VDL Mode 4 and Mode S extended squitter.

Point-to-point data communication will be provided by both VDL mode 2 and VDL mode 4. VDL Mode 4 will progressively replace VDL Mode 2 to ATS support high QoS services.

The new generation satellite system would also be used to provide broadcast data services (withdraw of multiple point-to-point transaction to support broadcast services (such as D-FIS) out of VHF datalink) and will complement VDLs for point-to-point communications in continental regions. This system will also provide datalink services where terrestrial infrastructure cannot be implemented (e.g. under-populated region, oceanic), replacing the AMSS current system.

For the same goal (minimisation of the VHF load), data communication would be provided over gatelink at large airports where a large amount of data is foreseen to be exchanged.

AVANTAGES OF SCENARIO 1

Replacement of poor HF quality voice communication by a new up to date satellite system.

Broadcast data communication provided by a mean adapted to the service topology.

DRAWBACKS OF THE SCENARIO 1

Critical on board integration and simultaneous operation of several VHF radio (2 mandatory radio supporting voice, VDL Mode 2 radio at least for AOC and perhaps for ATC, one (or perhaps 2) VDL Mode 4 radio to support ATN-ATC traffic and a minimum of 2 VDL Mode 4 radio to support ADS-B (which means at least 6 simultaneous VHF radio operating simultaneously on quite close channels)

Large number of VHF frequencies to be reserved region wide for the VDLs (in the view of the current figures available (September 2001), assuming that the size of guard band for VDL Mode 4 will be the same than for VDL Mode 2, 1 guard band is required each side of a VDL frequency).

Two major services (Communication and Surveillance) are using the same frequency band with the related consequences of a single mode of failure in case of frequency jamming

SCENARIO 1 - ISSUES TO BE INVESTIGATED

Multiple VHF systems to be integrated on-board (voice, VDL Mode 2 (at least for AOC for a long period), VDL Mode 4 for ADS-B, VDL Mode 4 for ATN) and to be operated simultaneously.

On-board architecture and integration of multiple systems (satellite, Gatelink and multiple VHF systems).

Availability of spectrum to satisfy the VHF frequencies requirements to support the various services and systems operating in the VHF band while considering the transition period during which VDL Mode 2 and VDL Mode 4 will be operated simultaneously requiring dedicated sub bands for each system. Furthermore the consequence of the decision to accept or not toaccomodate on the same system and/or frequencies AOC and ATS traffic need to be assessed in term of impact on spectrum availability.

SCENARIO 2

SCENARIO 2 DESCRIPTION

This scenario is essentially based on the introduction of VDL mode 3 for voice and point-to-point data communication and UAT/Mode S extended Squitter for surveillance services.

VDL Mode 3 voice services will progressively replace services provided over the Analogue VHF based systems in the continental regions.

Since for voice, no new system is able to support long range communication, HF services still need to continue to be provided as well as AMSS in regions (Asia, oceanic).

ADS-B services will be supported using UAT and Mode S extended squitter.

Point-to-point data communication will be provided by both VDL mode 2 and VDL mode 3 and services will migrate progressively from VDL Mode 2 to VDL Mode 3.

For minimising the VHF load, data communication would be provided over gatelink at large airports where a large amount of data is foreseen to be exchanged.

For under-populated regions, HF/Datalink and AMSS will be generalised.

AVANTAGES OF SCENARIO 2

Separation of Communication and Surveillance services using different frequency bands.

DRAWBACKS OF THE SCENARIO 2

Majority of the traffic based on the VHF band with a limited spectrum available.

Difficulty to migrate from the 8.33 kHz system to VDL Mode 3 (move from narrow channels (8.33 kHz) to wider channels (25 kHz)-) in region where 8.33 is implemented

No improvement of the voice quality in some region (still provided over HF (quality) or AMSS (access time and delay) ) regions

SCENARIO 2 - ISSUES TO BE INVESTIGATED

On-board integration of multiple systems (VDL, UAT, Gatelink, HF, AMSS).

VHF Frequency availability.

Migration from 8.33 to VDL Mode 3 where 8.33 is implemented.

Clarification of the voice communications (2) and data VDL Mode 3 and VDL Mode 2 links to be established at the same time (VDL Mode 2 being assumed to be operated for a long time at least for AOC) and consequence on the airborne architecture and on the management of the communications (and the impact on number of simultaneous frequencies required).

Migration of VDL Mode 2 to VDL Mode 3 (Business case for Service Providers vis-à-vis Mode 3 for AOC).

SCENARIO 3

SCENARIO 3 DESCRIPTION

This scenario is based on moving as much as possible services out of the VHF band.

New generation satellite system will be used to provide voice services in the very upper airspace (subject to a clear transition scenario) and under-populated airspace (replacing the HF voice systems and AMSS currently used in some regions) and to provide broadcast and point-to-point data communication services in complement of the VDL Mode 2 system in all the airspace.

Wideband based systems will be operated in the vicinity of the airports to provide voice communication and high capacity data traffic

Surveillance services will be provided over UAT and Mode S extended Squittter.

AVANTAGES OF SCENARIO 3

Large throughput in the terminal areas

Broadcast data communication provided by a mean adapted to the service topology.

Separation of Communication and Surveillance services on different spectrum bands.

Replacement of poor HF quality voice communication by a new up to date system.

DRAWBACKS OF THE SCENARIO 3

On-board integration of a multiple new systems. This integration is less technically critical than in the scenarios 1 and 2.

Cost due to the coexistence of several technologies (airborne architecture)

SCENARIO 3 - ISSUES TO BE INVESTIGATED

Multiple systems (VDL, UAT, Gatelink, Wideband, satellite). (Including the cost aspect).

Wideband systems to be investigated.

Frequency availability for the new technologies

Definition of the transition scenario for the voice migration from VHF to satellite or wideband.

12.0 Institutional Aspects

Comments to: cloisy@estec.esa.nl

Standardisation

Certification

Radio Spectrum Allocation

Implementation planing

Service provisions

Costs considerations

Intellectual Property

13.0 Summary and Conclusion

14..0 Recommendations to AMCP/8

Appendices

Appendix X: Definitions and Acronyms

Appendix Z: Info

The requirements found herein are defined from the perspective of an ATS Service Provider procuring AM[R]S from a Communication Service Provider (CSP) on the basis of a jointly agreed Service Level Agreement (SLA), irrespective of choices of communication technologies and means, i.e. land- or satellite-based.

This appendix contains material which was taken out of the main body of the document for possible further consideration or as a reminder.

Type of communication Services; Services : Air-Ground, Air to Air, Simplex-Duplex ?, Voice-data.

Parties: Controller, Pilot, Airborne host computer, ATC/ATM host computer, Airline host computer. (Other airspace users?)

Applications: CPDLC, ADS A through Z, FIT, FIS, PIT etc….

Ref:

Papers from AMCP

RTCA/AEEC/ Eurocontrol

Frequency band of operation:

Range/power/bandwidth

Symmetric/Asymmetric traffic.

Ref :

ITU R M 1079

Papers from AMCP

References

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[1] Only some frequencies available for ATC purpose in this band.

[2] Band shared with non safety services.

[3] continual - repeated regularly and frequently

continuous - without interruption or cessation

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