ADS Technology Assessment Task

Transcription

1 EUROPEAN ORGANISATION FOR THE SAFETY OF AIR NAVIGATION EUROCONTROL EUROCONTROL ADS Programme ADS Technology Assessment Task Edition: 1.0 Edition Date: Status: Class: Final Draft EATCHIP EUROPEAN AIR TRAFFIC CONTROL HARMONISATION AND INTEGRATION PROGRAMME

2 DOCUMENT CHANGE RECORD The following table records the complete history of the successive editions of the present document. EDITION DATE REASON FOR CHANGE SECTIONS PAGES AFFECTED Draft All Draft Draft Draft Draft I, II, III VDL-4 Test Plan Review with SCAA I Mode S and ADS-C Test Plans II.5, IV Mode S Stage 0 Trial II ADS-B Trial Final Draft Page ii Draft Edition: 1.0

3 TABLE OF CONTENTS DOCUMENT CHANGE RECORD...ii TABLE OF CONTENTS... iii DOCUMENT CHANGE RECORD...II REFERENCES... VI ACRONYMS... VIII 1 INTRODUCTION GENERAL OBJECTIVE OF THE ADS TECHNOLOGY ASSESSMENT TASK STATEMENT OF WORK APPROACH ADS TECHNOLOGIES CONSIDERED SCOPE OF ASSESSMENT PERFORMANCE PARAMETERS GENERAL ACCURACY INTEGRITY RELIABILITY AVAILABILITY CONTINUITY OF SERVICE COVERAGE LATENCY SURVEILLANCE DATA REFRESH RATE CAPACITY ADDITIONAL ASSESSMENT CRITERIA GENERAL SECURITY RF/IF INTERFERENCE IMPLEMENTATION ISSUES AND FAILURE MODES EQUIPMENT AND STANDARDISATION MATURITY COSTS USE OF NON-SURVEILLANCE SPECIFIC COMMUNICATION INFRASTRUCTURES SPECTRUM/FREQUENCY AVAILABILITY REGULATORY ISSUES ENVIRONMENTAL ISSUES WORLD WIDE COMPATIBILITY TASK DEFINITION SUB-TASK 1: INFORMATION REVIEW...27 Edition: 1.0 Draft Page iii

4 8.1.1 Objective and Scope Deliverables Work Plan SUB-TASK 2: TRIALS Objective and scope Deliverables Approach Statement of Work Work Plan SUB-TASK 3: SIMULATION Objective and scope Approach Deliverables Statement of Work Work Plan SUB-TASK 4: TECHNICAL ISSUES Objective and scope Approach Deliverables Statement of Work Work Plan SUB-TASK 5: FINAL REPORT Objective and scope Approach Deliverables Work Plan SCHEDULE...37 ANNEX I ADS-B/VDL MODE 4 TEST PLAN...38 I.1 OBJECTIVES...38 I.2 TEST SYSTEM DESCRIPTION...39 I.2.1 Equipment...39 I.2.2 Test Facilities...39 I.3 PREPARATION TESTS...39 I.3.1 Software/Hardware testing...40 I.3.2 Integration tests...40 I.4 TECHNICAL EVALUATION TESTS...40 I.4.1 Configuration...40 I.4.2 Data recordings...40 I.4.3 Flight Trials...40 I.4.4 Data Analysis...41 ANNEX II ADS-B/MODE-S EXTENDED SQUITTER TEST PLAN...42 II.1 OBJECTIVES...42 II.2 TEST SYSTEM DESCRIPTION...43 II.2.1 Equipment...43 II.2.2 Test Facilities...44 II.3 PREPARATION TESTS...45 II.3.1 Software/Hardware testing...45 II.3.2 Integration tests...45 II.4 TECHNICAL EVALUATION TESTS...45 Page iv Draft Edition: 1.0

5 II.4.1 Configuration...45 II.4.2 Data recordings...45 II.4.3 Flight Trials...45 II.4.4 Data Analysis...46 ANNEX IIIADS-B/UAT TEST PLAN...47 III.1 OBJECTIVES...47 III.2 TEST SYSTEM DESCRIPTION...47 III.2.1 Equipment...47 III.2.2 Test Facilities...48 III.3 PREPARATION TESTS...48 III.3.1 Software/Hardware testing...48 III.3.2 Integration tests...48 III.4 TECHNICAL EVALUATION TESTS...49 III.4.1 Configuration...49 III.4.2 Data recordings...49 III.4.3 Flight Trials...49 III.4.4 Data Analysis...49 ANNEX IVADS-CONTRACT TEST PLANS...50 IV.1 ADS-C/ATN...50 IV.1.1 Inmarsat...50 IV.1.2 IRIDIUM...50 IV.1.3 VDL Mode IV.1.4 Mode S...50 IV.2 ADS-C/FANS Edition: 1.0 Draft Page v

6 REFERENCES 1. Project Management Plan, Eurocontrol ADS Programme, Ref. SUR/ET3/ST / Stage 0 Work Plan, Eurocontrol ADS Programme, Ref. SUR/ET3/ST / Development of appropriate recommendations on the required navigation performance (RNP) for approach, landing and departure operations, ICAO AWOP/16 WP/756, Report on Agenda Item 1, 28/06/97 4. Manual of ATS Datalink Applications, ICAO ADS Panel 5. ADS-B MASPS, DO-242, RTCA 6. VDL Mode 4 SARPs, AMCP/WG-D/VDL-4 VSG 7. Survey of Mediterranean airspace for ADS, Ref. SMAA/AENA-TEC-WP R1, Aena, ENAV, HCAA, and STNA 8. Analyse Options for Initial Air/Ground Data Networks, Ref. COM.ET2.ST15, Eurocontrol Air/Ground Communications Subgroup 9. Final report, Ref. AI-97-AM-1173, EMERALD Project 10. Summary of STDMA/VDL Mode 4 projects and standardisation activities, Swedish CAA 11. Final Trials Results Report, Ref. 8CS/185/46/1A/1/ERP07, ADS Europe Consortium, Final Trials Results Report, Ref. AO/90/HQ/BE/96, ADS Europe Consortium, Report on User Requirements, Ref. TR 1025, FARAWAY Consortium 14. Project Management Plan, Ref. EEC/SUR6E1/PRJ/001, EEC ADS Studies and Trials Project 15. Eurocontrol-FAA Technical Interchange Documents, Eurocontrol ADS Programme, Report on the Assessment of Air to ground Digital Links, R. Boisvert, AMCP/WG-D/VDL-4 VSG 17. VDL-4 Sync Burst Encoding Formats, Change Request 36, AMCP/WG-D/VDL-4 VSG 18. VDL-4 Channel Management, VDL-4 Manual App. D 19. Mode S Manual of Specific Services, ICAO SICASP 20. T4 Mobile Transponder and base Station, LFV/SAAB Dynamics [under development] 21. CATS Display, Carmenta 22. FREER-3 PMP, R. Irvine, EEC Page vi Draft Edition: 1.0

7 23. EEC ADS Facility Outline, C. Tamvaclis and N. Clark, Eurocontrol 24. STDMA Performance Simulator Manual, Version 4.0, LFV 25. Enhanced STDMA Performance Simulator Manual, Version 1.2, EEC 26. SPS Compliancy with VDL Mode 4 SARPs, L. Rabeyrin, EEC 27. Enhanced SPS validation, L. Rabeyrin and C. Tamvaclis, EEC 28. FREER-3 Trials Report, L. Rabeyrin, C. Tamvaclis, and G. Rambaud, EEC 29. Mode S/UAT Link and Display Processor, II Morrow 30. Frankfurt Mode S Trial, DFS/FAA 31. Mode S Monitoring Trial, STNA 32. Flight Trials of ATN with Multiple Subnetworks (FITAMS) Preliminary Report, Issue 1.0, Ref DED6/ATNCF/ATIF_FITAMS/DCO/011, Eurocontrol, Performance measurement of ADS/ATN and ADS/FANS1 systems, L. Espeyt, B. Simmenauer, Issue 1.0, Sofreavia, VDL Mode 2 Test Plan, VDL Mode 2 Validation Programme, IRIDIUM Aviation Datalinks for ADS, Version 1.0, AleniaMarconi, IRIDIUM Aeronautical Service for ATM Trial Proposal, Ref. EEC/SUR6E1/WP/025, EEC, EEC/NATS ADS Trial Performance Assessment Plan, Ref. SDD/TP/01, NATS, ADS-C/ATN/Inmarsat Transit Delay Analysis, Ref. EEC/SUR6E1/EXP/004, EEC, 1999 Edition: 1.0 Draft Page vii

8 ACRONYMS ACARS ADS ADS-B ADS-C ADSP AIRSAW AMCP ASAS ATN CDTI CEC COM-T ECAC EUROCAE FAA FITAMS GSC HF ICAO LSC MASPS Mode S MOPS Aircraft Communications Addressing and Reporting System Automatic Dependent Surveillance Automatic Dependent Surveillance Broadcast Automatic Dependent Surveillance Contract (also known as addressed ADS) ADS Panel (of ICAO) Airborne Situation Awareness and co-operative separation (ODIAC taskforce) Aeronautical Mobile Communications Panel (of ICAO) Airborne Separation Assurance System Aeronautical Telecommunications Network Control Display of Traffic Information Commission of the European Community EATCHIP Communication Team European Civil Aviation Conference European Organisation for Civil Aviation Electronics Federal Aviation Administration Flight Trial of ATN with Multiple Subnetworks Global Signalling Channel High Frequencies International Civil Aviation Organisation Local Signalling Channel Minimum Aviation System Performance Standards (RTCA) Mode Selective secondary surveillance radar Minimum Operation Performance Standards Page viii Draft Edition: 1.0

9 (AEEC/EUROCAE) MSSR MTL NGSS ODIAC PMB PSR RASA RTCA SARPs SCORS SDPD SF21 SPS STDMA SUR-T TCP TSD UAT VDL VHF WBS Monopulse Secondary Surveillance Radar Minimum Triggering Level New Generation Satellite Systems (for example IRIDIUM) Operational Development of Integrated Air/ground data Communications group Programme Management Board Primary Surveillance Radar Requirements Analysis, Strategy and Architecture (an advisory sub-group of the SURT) Radio Technical Commission for Aeronautics Standards and Recommended Practices (ICAO) Surveillance Concept and Requirements (ODIAC taskforce) Surveillance Data Processing and Distribution Safe Flight 21 (Trials organised by the FAA and the Cargo Airlines Association) STDMA Performance Simulator Self organising Time Division Multiple Access EATCHIP Surveillance Team Trajectory Change Point Traffic Situation Display Universal Access Transceiver VHF Digital Link Data Link Very High Frequencies Work Break-down Structure Edition: 1.0 Draft Page ix

10 1 INTRODUCTION 1.1 General The EUROCONTROL Automatic Dependent Surveillance (ADS) Programme [1] includes all necessary actions to achieve the initial implementation and operational use of ADS in Europe. The first objective of the ADS Programme is to determine if ADS, as either sole means or in conjunction with other surveillance sources, can meet the operational requirements for surveillance for the medium and long-term. In parallel with this it has to be assessed whether ADS as a concept and the various corresponding candidate ADS-Broadcast and ADS-Contract (addressed ADS) technologies are safe and cost-beneficial for deployment in ECAC airspace. The second objective of the Programme, subject to a positive outcome of a corresponding business case, is the local implementation of operational systems (i.e. deployment of ADS infrastructure in ECAC) and the maintenance and support activities for those systems. The ADS Programme has four Stages, following the general EATCHIP life-cycle approach. Stage 0 [2] of the Programme is essentially the development of operational and technical requirements, the development of initial functional and performance specifications and an initial system analysis. A key objective of this stage is to evaluate the various ADS candidate technologies to assess the applicability of the technology to support the operational and technical requirements of ATS/ATM functions. This is achieved through a variety of techniques including studies, prototyping and trials. Stage 0 concludes with the development of an initial CBA to assess the cost and benefits of ADS in ECAC. Stage 0 will be complete in Stage 1 of the Programme aims at the completion the functional and performance specifications and feasibility assessment for the various ADS sub systems. This is achieved through a variety of techniques including studies, prototyping and trials. Stage 1 concludes with the development of a business case for pre-operational development of ADS (i.e. Stage 2). Stage 1 is expected to be complete in Stage 2 focuses on pre-operational development in order to validate both technical and operational aspects of the proposed European ADS infrastructure. Early in this Stage Convergence and Implementation Programme objectives and Aeronautical Information Circulars will be drafted. Stage 2 is expected to be complete in Stage 2 will result in a business case to proceed to Stage 3. Stage 3 consists of Local Implementation - the responsibility of the national Administrations and Organisations - together with common maintenance and support as a centralised activity. The planning for this Stage is consistent with a first operational date of 2007, as required by the Surveillance Strategy. The ADS Technology Assessment Task is part of Stages 0 and 1 of the ADS Programme. It will be followed by the pre-operational ADS system validation task in Stage 2. In this document, the term ADS is used to indicate both ADS-Broadcast (ADS-B) and ADS-Contract (ADS-C). Page 10 Draft Edition: 1.0

11 1.2 Objective of the ADS Technology Assessment Task The ADS Technology Assessment Task has the following objective: To gather information and subsequently evaluate existing and future ADS candidate technologies from a surveillance perspective. The assessment of technology and recommendations for pre-operational development and evaluation will be made before STATEMENT OF WORK The task will consist of the following activities: Identify and collect existing documentation on ADS technologies and related trial/simulation reports. For ADS-B the following technologies will be evaluated (operation air-to-ground, air-to-air, and surface movement): VDL Mode 4, Mode S extended squitter, and UAT. For ICAO CNS/ATM-1 SARPs compatible ADS-C, all ATN compatible aviation datalink technologies will be considered (operation air to ground) including satellite, VHF, HF and Mode S. The case of ADS-C/FANS-1 will also be assessed (operation air-to-ground). Establish characteristics to use for subsequent assessment (when all facts are known). Conduct complementary capacity and performance assessment studies and trials on ADS technologies. In Stage 0, new trials will focus on those technologies that are considered the most likely candidates for European implementation, i.e. VDL-4 and Mode S Extended Squitter, while ongoing ADS-C trials will be continued Compare the findings for the various technologies identifying weaknesses, performance characteristics, costs, reliability and safety issues. Analyse the design and performance of each of the above technologies in order to determine the capability of the technologies to support the potential applications, which will be identified by the Operational Concept and Technical Requirements Taskforce of the ADS Programme. Identify ADS technology issues that require further experimentation and analysis in subsequent stages of the ADS Programme. The work will be performed in collaboration by the Eurocontrol Experimental Centre and all interested Stakeholders. 3 APPROACH Initially the task will concentrate on establishing the technical characteristics of the various ADS datalink technologies independently of the ADS application requirements and operational scenarios for their use. The approach recognises that the requirements for ADS systems are not yet internationally agreed, and therefore the technical assessment must gather data with this fact in mind. Edition: 1.0 Draft Page 11

12 The first activities of the task will be to: review existing documentation, conduct trials to gather information, conduct simulations to gather information, undertake paper studies to assess other system characteristics. Subsequent analysis in Stage 1 will use the established datalink characteristics to assess the various technologies in the context of particular operational scenarios and application requirements. The assessment task recognises the urgency of technology decisions, particularly in the area of ADS-B. Therefore Stage 0 activities will focus on ADS-B while ongoing work on ADS-C will be continued. The candidate technologies and the definitions of the technical characteristics to be considered are listed in the following sections. The investigation of these characteristics will start with the analysis of already published reports. Where ambiguities remain, additional experiments/simulations/trials will be organised with the collaboration of any interested Member States, Industry, Airlines and others (e.g. FAA, Cargo Airlines Association, Russia, etc). Experiments and simulations will serve to provide calibration data for the simulations and also to validate as far as possible the simulation assumptions and the correct operation of the simulation tools. All assumptions will be fully documented. Assumptions about operational requirements will be kept to a minimum, and where they are made sensitivity analysis will be performed. Traffic forecasts, required for simulations and other activities will be based on CFMU forecasts where possible. Regional variations in traffic density will be taken into account by distinguishing five regions (Nordic, Core, Mediterranean, Atlantic, Eastern). 4 ADS TECHNOLOGIES CONSIDERED The following ADS technologies will be considered in this task ADS-B: Mode S extended squitter VDL Mode 4 UAT ADS-C: ATN over VDL Mode 2/3/4, Mode S, Inmarsat, and IRIDIUM FANS-1/ACARS via VHF, HF, and Inmarsat Page 12 Draft Edition: 1.0

13 ADS-B technologies will be considered for air-to-ground, air-to-air and surface movement operation. ADS-C over ATN and FANS-1 will be compared, along with the various subnetworks that can be used in each case. The use of combinations of technologies is beyond the scope of the technology assessment task at least in Stage 0. This issue will be addressed by the ADS System Architecture Taskforce on the basis of the characteristics of each technology as identified in the ADS technology assessment. Edition: 1.0 Draft Page 13

14 5 SCOPE OF ASSESSMENT The (end to end) boundaries of the ADS system are defined in [1] as shown in the figure below. Surveillance System Mobile ADS applications may include CDTI/TSD, ASAS etc. Mobile ADS Applications Other surveillance sources TIS, TCAS etc. ADS System SDPD Data sources (e.g. navigation) Data sources (e.g. navigation) ADS Datalink Ground Mobile ADS Functions Air Mobile ADS Functions Ground ADS Base Functions Ground Infrastructure Ground SDPD ATC Surveillance Applications SDPD Controller Display, surveillance functions (STCA), etc Mobile ADS functions may be on aircraft and vehicles Mobile ADS Applications Mobile ADS applications may include CDTI/TSD, etc. Other surveillance sources TIS, TCAS etc. The scope of the ADS technologies assessment task is indicated by the red box (ADS datalink). This task will seek to assess the characteristics of the technologies that can be used to implement the mobile and base ADS functions and the associated ADS communications systems. The ADS technology assessment depends on the ADS operational concepts and applications to be supported as well as the ADS system architecture. ADS Programme has established two Taskforces (ADS Concept and Technical Requirements, and ADS Architecture) which will define the ADS operational concept, applications, and the system architecture to be assumed in the technology assessment. The technical criteria will be established in collaboration with the above taskforces taking into account the Required Surveillance Performance Characteristics which are under development by ODIAC. Initially technology assessment will proceed on the basis of the characteristics and criteria described in the following section. Page 14 Draft Edition: 1.0

15 6 PERFORMANCE PARAMETERS 6.1 General This section defines high-level performance parameters that may be used to specify ADS datalink performance. From these, it identifies the basic studies and data that need to be measured or calculated through practical activities. The precise measurement activities to be undertaken will be defined in the Test Plans for each ADS technology. The general approach in this section is as follows: Determine high-level performance parameters. These will describe the performance of the surveillance or ADS system as a whole. User (operational) requirements can be specified in terms of these parameters. Determine measurable or calculable parameters which can be investigated in the practical assessment activities. These parameters will reflect the performance of a part of the system, e.g. the ADS datalink. There must be traceability between the high-level performance parameters and the low-level (measurable or calculable) parameters. Low-level parameters may be specified in equipment specifications or standards such as MOPS. For example, the time taken for an equipment to process and transfer a message (latency) will be defined in equipment standards. An example of high and low-level parameters for latency is shown in Figure 2. Figure 2: Example of performance parameter: Latency Surveillance System latency ADS datalink latency ADS Equipment 1 latency ADS Equipment 2 latency Data source (eg navigation) ADS Equipment 1 ADS Equipment 2 SDPD User ADS Mobile systems (eg aircraft or vehicle) ADS Base system Other surveillance sources Edition: 1.0 Draft Page 15

16 The following high-level performance are discussed in this section 1 : Accuracy Integrity Reliability Availability Continuity of service Coverage Latency Surveillance Data Refresh Rate Capacity RTCA [5] has also introduced the concept of Required Monitoring Performance (RMP). Monitoring Performance refers to capabilities of an airspace user to monitor other users and be monitored by other users and ATS at a level sufficient for participation of the user in both strategic and tactical operations. RMP is intended to characterise aircraft path prediction capability 2 and received accuracy, integrity, continuity of service, and availability of a monitoring system for a given volume of airspace and/or phase of operation. ADS-B delivery technologies, data definition, and applications must conform to appropriate RMP specifications on an end-to-end basis. 6.2 Accuracy General Definition [3]: The degree of conformance between estimated or measured position (and other relevant parameters such as velocity and time) of a platform and its true position (or velocity or time). Accuracy requirements may be specified for each element of the data transmitted. For example, position accuracy, velocity accuracy, next waypoint accuracy and timestamp accuracy. Surveillance system accuracy needs to be defined as a requirement on the SDPD output and also on the mobile ADS application inputs. This will in turn generate requirements on the ADS datalinks. ADS datalink accuracy will not be considered in the technology assessment because it is not a technology dependent issue. ADS datalink accuracy depends on the accuracy delivered by the data sources. ADS cannot increase the accuracy of the navigation data that is provided to it (unless navigation data processing capability were to be embedded in the mobile ADS equipment). ADS may reduce accuracy through precision loss due to the ADS data encoding techniques used. The effect of such techniques can be assessed through analysis (no measurements 1 Some parameters are highly dependent on equipment configuration settings (for example transceiver TX power) requiring sensitivity analysis to ensure that performance over a range of operating conditions is achieved. Also, some parameters depend on the traffic load (for example latency). Sensitivity analysis on the traffic load may be conducted via simulations 2 Aircraft path prediction capability is defined by a 95 percent position uncertainty volume as a function of prediction time over a specified look ahead interval. Page 16 Draft Edition: 1.0

17 are required) and in any case the same data encoding techniques tend to be used in most ADS technologies. The ADS equipment expects a time source which is used to timestamp the ADS reports. Some ADS technologies however, also require a time source for synchronisation purposes and may rely on the ADS report timestamps for their operation. The impact of time accuracy on the operation of the ADS technologies is within scope of the assessment. Activities required in practical accuracy assessment: Experimentation and simulation of ADS datalink operation for a range of time synchronisation accuracy values corresponding to the use of embedded and external GPS and DGPS. This should be necessary only on technologies sensitive to synchronisation loss, i.e. VDL Mode Integrity General Definition [4]: the trust which can be placed in the correctness of the information provided. Integrity is generally measured in terms of the probability that errors will be mis-detected. This may be when a correct message is indicated as containing one or more errors, or when a message containing one or more errors is indicated as being correct 3. Surveillance system integrity is achieved through confidence that the surveillance data presented to the user is accurate. Surveillance integrity violations including ADS integrity violations have to be handled by the surveillance applications and/or the SDPD. This aspect should be investigated in the overall surveillance system integrity analysis to be performed in Stage 1. The ADS technology assessment task will not consider integrity violations due to data source malfunction as this aspect is ADS technology independent. Nevertheless the ADS datalink may introduce errors into the data that it conveys, due to for example processing errors, RF signal variations beyond system design thresholds, or transmission collisions. Equipment standards (such as MOPS) and specifications will include tests to ensure that data are processed correctly by equipment. Communication protocol specifications may include error detection (and for ADS-C error recovery) features to ensure the integrity of the communicated messages. Nevertheless there always remains a statistical chance of message errors being undetected (known as undetected error rate). This undetected error rate may be calculated by analysis, if the underlying uncorrected error rate is known. In practice only the uncorrected error rate is measurable since systems are usually designed to deliver a very low undetected error rate. Activities required in practical assessment: Measure the underlying uncorrected error rate for each ADS technology in association with the message success rate analysis done for reliability assessment (see Sec. 6.4) ; 3 RTCA integrity definition for ADS-B [5]: the probability of an undetected error in a report received by an application, given that the ADS-B system is supplied with correct source data. Edition: 1.0 Draft Page 17

18 Identify ADS equipment integrity performance stated in equipment specifications and compare with relevant MOPS Analyse integrity per technology using the results of (a) and (b). Assess ADS technology maturity in terms of conformance to integrity requirements that will be defined by the Operational Concept and Technical Requirements Taskforce. 6.4 Reliability General Definition [4]: The probability that the system will deliver a particular message without errors (also known as Message Success Rate or MSR). Errors include message corruption and also loss and duplication. The difference between reliability and integrity (see Sec. 6.3) is that integrity includes errors due to the data source while reliability does not, and reliability takes into account message loss/duplication as errors while integrity does not. For the surveillance system, reliability is achieved through confidence that the requested surveillance data will be delivered to the user, consequently the MSR must exceed a confidence threshold. MSR is a more critical performance measure for ADS-B datalinks than for ADS-C ones (particularly over ATN) because broadcast protocol stacks usually include less robust error recovery procedures than point to point ones. MSR also affects the Effective Update Period (see Sec. 6.9). MSR needs to be measured for 1,2,3, consecutive messages (squitters, sync bursts etc.) in the technical assessment per technology and it ought to be validated with calculations of expected link performance. The MSR will vary as a function of: Range Bearing between transmitting ADS-B equipment (aircraft) and receiving ADS- B equipment (aircraft or ground). Coverage scenario, i.e. air-to-ground, air-to-air or ground-to-ground Traffic load Activities required in practical assessment: Measure via experiments and simulations MSR per ADS technology as a function of range, bearing, coverage type, and traffic load. Assess ADS technology maturity, i.e. conformance to reliability requirements that will be defined by the Operational Concept and Technical Requirements Taskforce. Analysis is required of MSR to validate the measured MSR 6.5 Availability General Definition [4]: The ability of a system to perform its required function at the initiation of the intended operation. It is quantified as the proportion of the time the system is available to the time the system is planned to be available. Availability is used to define requirements on continuous system operation over a long period of time (e.g. max downtime of 14 minutes per year). Downtime due to Page 18 Draft Edition: 1.0

19 maintenance is not included. Availability is quite different from continuity, as discussed below. Surveillance/ADS System Availability is dependent on wide-area failure mechanisms (e.g. failure of a ground station). Such failures must to be addressed, and the ADS technologies assessment task needs to provide data on the failure modes per ADS technology. Malicious threats need also to be addressed. This is a security issue and the ADS technologies assessment task will provide data on the security risks per ADS technology. ADS datalink availability depends on equipment availability (e.g. MTBF), architecture and implementation (e.g. dual equipage). Equipment availability standards are set in the relevant MOPS. ADS datalink availability standards have been defined by the ADS Panel [4] and RTCA [5]. The ADS programme will need to ensure that required levels of availability can be achieved with realistic architectures and implementations. The ADS technologies assessment task has to evaluate equipment and technology maturity concerning conformance to the availability requirements Data link performance can also be considered to impact on availability and this will be discussed below. Activities required in practical assessment: Analysis of failure modes per ADS technology (see Sec. 7.4). Analysis of security risks per ADS technology (see Sec. 7.2) ADS technology maturity assessment (see Sec. 7.5): Conformance to availability requirements that will be defined by the Operational Concept and Technical Requirements Taskforce. 6.6 Continuity of Service General Definition [4]: The probability of a system to perform its required function without unscheduled interruptions during the intended period of operations 4. Continuity is used to define continuous system operation over a short period of time (e.g. hour of flight in [5]). Continuity is quite different from availability: a system can have a low availability (e.g. because it is often switched off for maintenance) but a high continuity (because it never breaks). Continuity is normally associated with safety critical manoeuvres an aircraft should not start a CAT III ILS approach unless confident that the ILS will still be there by the time it lands. 4 RTCA continuity definition for ADS-B [5]: The probability that the ADS-B System, for a given ADS-B Message Generation Function and in-range ADS-B Report Generation Processing Function, is unavailable during an operation, presuming that the System was available at the start of that operation. The allocation of this requirement to ADS-B System Functions should take into account the use of redundant/diverse implementations and known or potential failure conditions such as equipment outages and prolonged interference in the ADS-B broadcast channel. Edition: 1.0 Draft Page 19

20 Both the ADS Panel [4] and RTCA [5] define continuity requirements for ADS. The application of these requirements to ADS in the ECAC Airspace will be determined by the ADS Concept and Technical Requirements Task Force. Until further guidance is received on the application of ADS continuity requirements, the ADS Technologies Assessment Task will use the cumulative inter-arrival distribution of ADS periodic reports (see Sec. 6.9 on the Surveillance Data Refresh Rate) as a measure of continuity of service. Activities required in practical assessment: See Sec Coverage General Definition [16]: The operational geographic area (or volume) within which the system provides a service. Surveillance system coverage refers to the range of the entire surveillance system, which will be a combination of the coverage of the various surveillance subsystems. ADS datalink coverage refers to the range of the candidate data links used for ADS. This is a key measure of performance for the ADS technologies assessment task. In the case of ADS-B, coverage can be measured in three scenarios: 1) air-to-ground range; 2) air-to-air range (measured between 2 ADS-B stations on aircraft) 3) surface movement range (measured between ADS-B stations on the ground). Item (3) is very sensitive to terrain profile, airport layout, buildings, etc, which make it hard to characterise generically. The ADS technologies assessment task will describe surface movement coverage qualitatively or around selected airports. Activities required in practical assessment: ADS-B datalink coverage must be measured for the three scenarios described above. ADS-C datalink coverage will be considered only for the air to ground case. 6.8 Latency General definition: The elapsed time between a system input and the corresponding system output. ICAO ADSP [4] uses the term transfer delay for ADS-C and the term latency for ADS-B, defining transfer delay as the elapsed period from the time at which the originating user initiates the triggering event until the time the transmitted information has been received by the intended recipient. Surveillance system latency refers to delay between surveillance measurements being made (e.g. radar transponders or navigation data being valid) and the surveillance information being presented to a user. This needs to be defined Page 20 Draft Edition: 1.0

21 for the overall surveillance system and the latencies introduced by various components can be added together to determine the overall latency. ADS system and ADS equipment latency refers to time delays across parts or all of the ADS system as data. RTCA [5] defines ADS-B latency as the elapsed time from the time of applicability of the aircraft s or vehicle s ADS report until the reception of that ADS report is completed. This parameter is ADS technology and implementation specific and may vary considerably according different manufacturers equipment architectures and components. Latency across individual pieces of equipment is usually specified in documents such as MOPS, which are used for certification of airborne equipment. There is little point in measuring latency across individual equipment sets except for validation of conformance to MOPS. The datalink latency of ADS-B technologies is inherently low except under traffic load conditions (that aspect will be considered in the capacity assessment). It is therefore of little interest to measure ADS-B latencies except for complex messages (such as long term intent) involving the transmission of multiple datalink bursts or squitters. On the contrary, the datalink latency of ADS-C technologies is a major distinguishing feature and will have to be measured for each technology. Then, the main parameters of interest are: a) ADS basic report transfer delay (elapsed time from the time of applicability of the aircraft s or vehicle s ADS report until the reception of that report in the destination ADS system) ; b) ADS Contract response time (elapsed time from the creation of an ADS-C Contract Request or Cancellation at the ground ADS station to the reception of the corresponding acknowledgement downlinked by the aircraft ADS station) There are also technology specific delay parameters that have to be considered, such as network entry time for VDL Mode 4. Such parameters are identified in the test plans for each technology. Activities required in practical assessment: ADS-B: Measurement of the latencies of complex messages involving the transmission of multiple datalink bursts/squitters ADS-C: Measurement of Basic Report Transfer Delay, Contract Response Time and transfer delays for composite ADS reports (Position plus speed vectors plus intent) 6.9 Surveillance Data Refresh Rate General Definition: The rate at which new surveillance information is supplied to the user. The required surveillance data refresh rate is usually associated with a probability of achieving the update rate (for example, it could be specified as 99% probability of an update every 10s ). Edition: 1.0 Draft Page 21

22 For the surveillance system, the Surveillance Data Refresh Rate is the rate at which the system delivers new information to the surveillance users. For the ADS datalink, the surveillance refresh rate is related to the Transmission Rate (TR), i.e. the nominal rate at which reports are transmitted by the source ADS station; Successful Reception Probability (also known as message success rate [MSR]), i.e. the probability of successful reception of a report by a destination ADS equipment. The MSR is a reliability measure (see Sec. 6.4). Effective Update Period (EUP): Elapsed time between successive ADS report updates (from the same ADS station) at the output of the destination ADS system. In practice, the TR is configured (dynamically in ADS-C) according to the application scenario requirements, but it is subject to the constraint of maximum system capacity. The EUP 5 needs to be measured in terms of cumulative probability over time (e.g. the probability that the EUP will not exceed a threshold over a given time period). Activities required in practical assessment: Measure MSR Measure EUP cumulative distribution over fixed time periods Capacity Channel capacity may be defined as the number of ADS stations that can operate concurrently within range within a given frequency band. ADS system capacity is a combination of channel capacity over a geographic area over a number of channels (if appropriate). Capacity is dependent on the technical performance (as defined in Sec. 6 above) threshold considered as acceptable for the ADS applications, and therefore depends on the operational scenarios. Capacity also depends on the ground infrastructure (number and/or location of ground stations, ground-ground link throughput) defined in the datalink configuration scenario. Capacity calculations will require simulations. Maximum reuse will be made of any existing tools but modifications may be necessary. Validation of the simulation tools used is critical. Activities required in practical assessment: Identify simulation tools per technology and validate. Define simulation scenarios in coordination with the ADS Technical Requirements Task Force and the ADS System Architecture Taskforce. 5 The mean EUP is often estimated from TR and SRP under the assumption that successive report arrivals are not correlated. Page 22 Draft Edition: 1.0

23 Measure capacity for different ranges of performance parameter target values. Edition: 1.0 Draft Page 23

24 7 ADDITIONAL ASSESSMENT CRITERIA 7.1 General This section describes assessment criteria that will be used to evaluate the ADS technologies in addition to the performance related criteria discussed in the previous Section. The following additional assessment criteria will be considered: Security RF/IF Interference Implementation Issues and failure modes Equipment and Standardisation Maturity Costs Use of Non-Surveillance Specific Communication Infrastructures Spectrum/frequency availability Regulatory issues Environmental issues World-wide compatibility Each of the above criteria is discussed in the following subsections. 7.2 Security The ADS technologies need to be assessed with regard to the potential impact of hostile attacks/intrusions to the ADS system and the available means and costs of protection. It has to be determined whether the ADS technologies present any different security vulnerabilities/risks. The costs of protection against the identified risks may also be different. Security assessment will begin with a paper study in Stage 0 to identify the potential security risks per technology, and any work that has been done to address them. Security issues will be addressed in more detail in Stage RF/IF Interference The ADS technologies need to be assessed with regard to the impact of unintentional RF/IF interference due to for example hidden terminals, coexistence of equipment on a/c, or low level RF power accumulation on reception. The initial assessment will consist of a paper study to evaluate critical interference issues due to spectral masks, and multiple antennas on the a/c. These issues will be addressed in more detail in Stage 1. Page 24 Draft Edition: 1.0

25 7.4 Implementation Issues and failure modes Each candidate ADS technology poses specific implementation issues. Such issues refer to aircraft and ground ADS datalink equipment and fitment. The particular issues posed by general aviation aircraft need be considered (for example ADS equipment/transponder power requirements). Transition issues also have to be considered. Failure Mode analysis is required per ADS technology and it is related to implementation issues. The use of backup modes will be considered by the ADS System Architecture Taskforce. In Stage 0 ADS technology assessment will identify critical issues per technology, which will be reviewed and prioritised for further study (in Stages 0 and 1) in collaboration with the ADS System Architecture Taskforce. 7.5 Equipment and Standardisation Maturity These aspects will be considered in the Business Case Task of the ADS Programme. The maturity of equipment and standards is different for each ADS technology. Eurocontrol and some Member States are active participants in the relevant standardisation bodies. Initially, the ADS technology assessment task will contribute information concerning equipment maturity for ADS-C/ATN/Inmarsat, ADS-C/FANS-1, Mode S extended squitter, and VDL Mode 4. A lot of information has already been collected for these technologies from past and ongoing trials and experiments at the Eurocontrol Experimental Centre and elsewhere. The UAT technology will also be assessed provided FAA and MITRE collaboration is forthcoming. 7.6 Costs Initially, rough cost data will be collected where possible to support the business case development. Cost estimates will be refined in later stages of the programme. 7.7 Use of Non-Surveillance Specific Communication Infrastructures The issues (benefits/costs/safety) posed by the potential sharing of communications infrastructures (for example VDL Mode 2, Inmarsat, etc.) with ATC applications other than surveillance (for example CPDLC) need to be explored. However such issues are dependent on the operational scenarios and application requirements, which will be defined by the Operational Concept and Technical Requirements Taskforce. These aspects will be addressed in more detail in Stage 1. Edition: 1.0 Draft Page 25

26 7.8 Spectrum/frequency availability Spectrum/frequency requirements will be determined from the operational scenarios, taking into account the capacity characteristics of the ADS technologies used. The availability of the required spectrum and frequency should be addressed via the Eurocontrol COM frequency management team. 7.9 Regulatory issues These issues will be addressed in Stage 1 by the Business Case task of the ADS Programme Environmental Issues Environmental issues such as RF emissions interfering with third parties ( for example TV, mobile telephones etc.) need to be assessed World wide compatibility The European implementation of ADS will need to take into account developments in other parts of the world. Collaboration with organisations such as the FAA will be pursued. Page 26 Draft Edition: 1.0

27 8 TASK DEFINITION 8.1 Sub-task 1: Information Review Objective and Scope The objective of this sub-task will be to review and analyse information that is already published concerning the candidate ADS technologies. In addition to the relevant standardisation bodies (ADSP, AMCP, SICASP, RTCA, EuroCAE, ETSI), the following sources of reports have been identified so far: Study of the Mediterranean and adjacent areas for ADS [7], EATCHIP.COM ST15 Report [8], EMERALD Report [9], Swedish CAA Studies and Trials including EC funded activities such as NEAN/NEAP/NAAP[10], ADS Europe Trials [11] [12], FARAWAY [13], Eurocontrol Experimental Centre ADS Studies and Trials [14], FAA Studies and Trials [15] Lincoln Labs Studies and Trials [15] MITRE Studies and Trials [15] Future VHF Study, Eurocontrol COM-2 VDL Mode 4 Timing Study, Eurocontrol COM-2 Additional source material will be identified and reviewed, as it becomes available. PMB participants and more generally Stakeholders will be invited to provide material for inclusion in the review Information sources will be verified to ensure that all technical statements can be fully justified Deliverables For each ADS candidate technology, a table will be produced listing for each characteristic identified in Sec. 6 the information indicated in the relevant documents, the source of the information, and the assumptions made. This table will be included in the final report. A list of outstanding issues will be produced with a reference to their source. The issues/characteristics for which there is consensus as well as those for which further work is necessary will be identified. Edition: 1.0 Draft Page 27

28 8.1.3 Work Plan In Stage 0 the task will focus on the following ADS technologies for which sources of information have already been identified ADS-B/VDL Mode 4 ADS-B/Mode S extended squitter ADS-C/ATN/Inmarsat ADS-C/FANS-1 Other ADS technologies including UAT will be assessed in Stage 1. Page 28 Draft Edition: 1.0

29 8.2 Sub-task 2: Trials Objective and scope This task will analyse and collate data gathered from trials and lab experiments to determine performance characteristics, provide inputs for the capacity analysis, and allow validation of the simulation tools. Technology specific issues will also be considered where appropriate. In accordance with the analysis presented in Sec. 6, the performance characteristics to be measured in this task are: Reliability: Message Success Rate versus range Refresh Rate: Message update period versus range Range: Comparison of Reliability and Refresh Rate curves with surveillance requirements such as those defined in the ADS-B MASPS Delay: This is critical in the case of ADS-C only. Both ADS-B and ADS-C are in the scope of the task.. Collaboration will be sought with all stakeholders and third parties conducting their own trials on any of the three ADS-B technologies. Existing trials equipment and infrastructures will be used wherever possible. Eurocontrol has extensive ADS-B (Mode S and VHF-STDMA) and ADS-C (ATN, Inmarsat, VDL Mode 2, Mode S) facilities at the EEC which have been made available for the ADS programme. Many Stakeholders also have trials facilities and they are expected to contribute to the trials data gathering task Deliverables Trials reports summarising the collected performance data and providing an assessment of the results. A summary of the results will be provided in the final report Approach Eurocontrol and other parties have already dome a lot of work on ADS-C particularly for ATN/Inmarsat, Mode S, and FANS-1. Consequently, in Stage 0, trial/experimentation activities will concentrate on the three candidate ADS-B technologies, e.g. VDL Mode 4, Mode S extended squitter, and UAT. Additionally, the ongoing trials on ADS-C/Inmarsat and ADS-B/FREER will be completed during Stage 0. Test plans comprising laboratory tests, flight trials and simulations will be developed for each candidate technology. The tests will consist of data gathering over a range of operating conditions. Edition: 1.0 Draft Page 29

30 Lab tests Lab or bench tests will take place at either the EUROCONTROL Experimental Centre or the lab facilities of partners. The aim of such tests is to gain detailed information on the performance of particular equipment under controlled and accurate conditions. Lab tests will be used to (a) Assess equipment conformance to standards and maturity (b) Measure performance parameters (defined in each test plan) under a variety of signal strengths and interfering sources. (c) Identify subsystem contributions to the measured parameters Flight trials Flight trials involve data gathering from experimental and where possible revenue aircraft flights. The data gathered will be analysed to measure performance and they will be controlled for consistency with lab test results and simulations. Ideally when the system configuration has stabilised performance recordings should be collected over a long period of time. However this may not be feasible due to time and budget constraints In comparison with lab tests simplifications will be necessary, to reduce the amount of data to be recorded. The results of the lab tests and flight trials should permit the prediction of general performance characteristics for each technology. They will also serve to provide input data for the capacity analysis, and to validate the simulation tools. Collaboration will be sought with other parties (such as Member States, Industry, Airlines, FAA, Cargo Airlines Association etc.) involved in ADS trials. Collaboration may be in the form of (a) joint definition of trial scenarios, measured data, and analysis methods. (b) providing data for analysis (c) sharing equipment and/or access to trials infrastructures (d) joint funding (e) sharing analysis effort and tools The following trials infrastructures have been identified as candidates for use in this task System Led by Technology NEAN/NUP LFV VHF-STDMA/VDL-4 FITAMS EEC Mode S extended squitter FREER-3 LFV/SAS/EEC VHF-STDMA Frankfurt Airport DFS/FAA Mode S extended squitter Mode S Monitoring STNA Mode S extended squitter ADS/ATN Update Trial NATS/EEC ADS-C/ATN/Inmarsat Safe Flight 21 FAA/Cargo Airlines VDL-4, Mode S extended squitter, UAT Page 30 Draft Edition: 1.0

31 System Led by Technology FARAWAY 2 Alenia, ENAV VHF-STDMA SACCAN AENA ADS-C over FANS-1/A Collaboration will be sought with the organisers of the above trials. The trials will not assume requirements for range, update rates, reception probability, etc. Performance over a range of each of these parameters will be investigated Statement of Work Initially trials and experimentation will be conducted on the following ADS-B technologies: VDL Mode 4 (see Test Plan in Annex 1) Mode S Extended Squitter (see Test Plan in Annex 2) UAT (see Test Plan in Annex 3) Data will also be gathered from the ongoing Eurocontrol ADS-C/ATN trials activities on Inmarsat (Collaboration with NATS) and Mode S (FITAMS trial), see Test Plan in Annex 4. Reports from the other trials mentioned in the previous section will be analysed. The following additional trials are considered for inclusion in this task A. DFS/FAA Mode S Extended Squitter Performance Trials : Characterise the performance of Mode S Squitter in a worst case operational environment Evaluate performance of improved Mode S reply processing algorithms Characterise use of 1030/1090 MHz spectrum, air-air and air-ground in Frankfurt/Main Evaluate performance of air-air hybrid surveillance in worst case operational environment This trial is scheduled to take place in the year Eurocontrol will seek to participate in this trial and possibly extend the trial activities to other core Europe locations. B. STNA ADS-B/Mode S Monitoring Trial: This trial aims at validating a concept of ADS-B data quality monitoring, thanks to the cross check of data included in extended-squitter reports with positions calculated by ground stations. Collaboration will be sought with STNA in conducting joint trials and in sharing the trial results. Edition: 1.0 Draft Page 31