VDL Mode 2 Capacity and Performance Analysis

Transcription

1 November Introduction: VDL Mode 2 Capacity and Performance Analysis The objective of this paper is to deliver the background and results of the SESAR Joint Undertaking (SJU) study on. 2. Background: High quality data communications capabilities, consistent and dependable, are essential enablers to support the implementation of efficiency and capacity improvements required by the Single European Sky. The mandated solution in Europe, Regulation (EC) No29/2009 as amended by Implementing Regulation (EU) 2015/310, is based on VDL mode 2 technology. However, as the operational use of VDL mode 2 for ACARS and CPDLC using ATN was progressively reaching the intended operational usage, certain performance degradation issues were observed that raised concerns on the overall usability of the system. These concerns led the European Commission to request EASA to investigate into the observed performance issues of this technology. The resulting EASA report included a ten point Action Plan involving proposals for simulations, performance assessment campaigns, flight trials and deployment planning needed before an informed decision on the future of VDL 2 implementation could be done. In this context, the SJU launched two projects focusing on VDL Mode 2: The is an SJU initiative launched prior to the EASA investigation. It was conducted between June 2014 and July The main objective of the study was the identification of the time horizon by which VDL Mode 2 (assuming usage of up to 4 frequencies) should reach its operational limits in Europe. The study was performed by a consortium led by ENAV depicted in figure 1. Figure 1: " "Consortium The results and conclusions are detailed in section 3 whilst the final report is available in the attachment (section 4). The strategic aim of this study was to assess the capability of VDL2 to support SESAR services on the long term and to determine the point in time by which the next generation datalink technology should be available. The VDL Mode 2 Measurement, Analysis, Testing and Simulation Campaign (also referred to as the ELSA Consortium study) was launched by the SJU further to a European Commission request. It addresses the EASA recommendations 1 to 6 related to the identification of the problem root cause and the provision of potential fixes. It aims at further analyzing the end to end VDL Mode 2 issues experienced today (through simulation and flight testing campaigns), defining potential technical solutions for multi-frequency deployment and VDL Mode 2 potential improvement (protocol optimization, etc.). The project started in February 2015 and is due to deliver the final report mid It is performed by a consortium led by NATS and actively involving a wide representation of stakeholders. The consortium is depicted hereafter in figure 2.

2 Figure 2: ELSA Consortium 3. Main findings of the : This section gives an overview of the. It aims at and providing guidance on the interpretation of the results. How to read the results: The results of the capacity study are based on assumptions, detailed within the document, proposed by the consortium as representing the most realistic scenarios until The VDL Mode 2 protocol considered was the one currently used by many European ANSPs/CSPs and required by the European Commission Regulation (EC) No 29/2009 requirements on data link services for the Single European Sky. Multi- Frequency options are proposed by the consortium, in terms of frequencies usage for better utilization of the four VDL Mode 2 channels. The ongoing ELSA study is expected to further develop the Multi- Frequency options and to conclude within its report on the final Multi-Frequency solution. It should be noted that the results of the study are valid within these assumptions. Dates where the VDL2 should reach the capacity limits highly depend on implementation options and on technical configurations. Changes to these assumptions (e.g., change of topology, introduction of more than 4 frequencies, and use of a complementary media to VDL2) are likely to impact the results. The main findings: Looking to a time window from 2015 until 2040 and considering various traffic growth expectations in Europe, the study defined the expected growth of ATS and AOC datalink traffic over that period. Based on in depth modelling of all the Air and Ground components, the simulation determined the VDL Mode 2 performance at the network level and also at each individual Ground Station level. The results enabled conclusions on where and when the VDL Mode 2 link would suffer from quality degradation making it no longer usable especially for ATS purposes. The main conclusions and recommendations that emerge from this report are summarized hereafter. o VDL2 over one single frequency would already reach its capacity limits in Therefore, Multi-frequency deployment in Europe is a MUST as of today (2015). o o o A 4 frequencies implementation is a minimum requirement to support VDL2 deployment until 2025 in high density area. Further optimisation options under investigation by ELSA may extend the viability of VDL2 over 4 frequencies beyond 2025 in high density area. It is highly recommended to anticipate the evolution of the European datalink infrastructure in the ATM masterplan and to prioritize the development of the next generation datalink technology within SESAR. These conclusions represent the main outcome of the study and do not represent formal recommendations to the European Commission on the next steps.

3 November The report: The detailed report of the is available hereafter.

4 VDL Mode 2 Capacity and Performance Analysis Document information Project Title Project Number Project Manager Deliverable Name Deliverable ID SESAR_CFT_0096 ENAV Edition Template Version Task contributors SESAR_CFT_0096 ENAV (Project Manager of the consortium), University of Salzburg, ENAIRE, DFS, NATS, LFV and supported by: DSNA, EasyJet, Air France, Lufthansa, SITA and Airbus. Abstract

5 Authoring & Approval Prepared By - Authors of the document. Name & Company Position & Title Date Michele Carandente / ENAV Project Manager 26/05/2015 Carl-Herbert Rokitansky / Uni of Salzburg Project Member 26/05/2015 Reviewed By - Reviewers internal to the project. Name & Company Position & Title Date Michele Carandente / ENAV Project Manager 26/05/2015 Carl-Herbert Rokitansky / Uni of Salzburg Project Member 26/05/2015 Jan Stibor / LFV Project Member 26/05/2015 Jerome Condis / Airbus Project Member 08/05/2015 Marc Speltens / SITA Project Member 08/05/2015 Luc Rochard / AirFrance Project Member 22/05/2015 Alan Pirovano / ENAC Reviewer 10/07/2015 Approved for submission to the SJU By - Representatives of the company involved in the project. Name & Company Position & Title Date Michele Carandente / ENAV Project Manager 26/05/2015 Carl-Herbert Rokitansky / Uni of Salzburg Project Member 26/05/2015 Raphael Pascal / Airbus Project Member 05/06/2015 Mario Garcia / ENAIRE Project Member 03/06/2015 Armin Schlereth / DFS Project Member 08/06/2015 Jan Stibor / LFV Project Member 26/05/2015 Marc Speltens / SITA Project Member 28/05/2015 Alan McNab / NATS Project Member 08/06/2015 Document History Edition Date Status Author Justification /04/2015 Draft M.Carandente Monofrequency outputs /04/2015 Draft M.Carandente Refinement of the strawman /05/2015 Draft C.-H. Rokitansky Summary of Results /05/2015 Draft C.-H. Rokitansky Multi-Frequency results and Update /05/2015 Draft M. Carandente Proposed Final /06/2015 Final M. Carandente Added reviews from partners /08/2015 Final M. Carandente Max Ehammer C.-H. Rokitansky /08/2015 Final M. Carandente Resolution of external comments (EASA, ECTL, ENAC, etc.) General review of the document /09/2015 Final M. Carandente Acknowledgement /10/2015 Final M. Carandente Added details on chapter 6 2 of 151

6 Table of Contents EXECUTIVE SUMMARY INTRODUCTION PURPOSE OF THE DOCUMENT INTENDED READERSHIP INPUTS FROM OTHER PROJECTS ACRONYMS AND TERMINOLOGY CONTEXT OF THE STUDY (OBJECTIVES) OBJECTIVE OF THE STUDY SIMULATION SETUP METHODOLOGY ASSUMPTIONS AND VARIANTS Assumptions on air traffic growth Assumptions on topology Assumptions on network subscription rate Assumptions on simulation time period Assumptions on aircraft equipage rate Assumptions on frequency management Assumptions on alternative communications means Assumptions on AOC and ATS Traffic Load SIMULATION SCENARIOS DESCRIPTION SIMULATION SCENARIOS SINGLE FREQUENCY SIMULATION SCENARIOS MULTI-FREQUENCY SUMMARY OF THE RESULTS VDL MODE 2 CAPACITY ASSESSMENT CRITERIA SINGLE-FREQUENCY DEPLOYMENT High traffic area Medium traffic area MULTI-FREQUENCY DEPLOYMENT High traffic area Medium traffic area CONCLUSIONS HIGH TRAFFIC AREA (LILLE) MEDIUM TRAFFIC AREA (ROME) REFERENCES APPENDIX A PROGRAMME MANAGEMENT A.1 WORK BREAKDOWN STRUCTURE A.1.1 WP1 Management A.1.2 WP2 Characterization of Applications A.1.3 WP3 Scenario Definition A.1.4 WP4 Simulation and reports A.2 DELIVERABLES A.3 SCHEDULE APPENDIX B SIMULATION MODELS DESCRIPTION B.1 MOBILITY MODEL B.1.2 Air Traffic data file B.2 TOPOLOGY MODEL B.2.1 Area of interest B.2.2 Ground Station characteristics of 151

7 B.2.3 Link Budget Model B.2.4 Mobility Management B.2.5 Deployment Options B.3 DATA APPLICATION MODEL B.3.1 ATS data traffic B.3.2 AOC data traffic B.3.3 End-to-End TRTD estimation B.4 PROTOCOL SIMULATION APPENDIX C DETAILED SIMULATION RUNS of 151

8 List of tables Table 1 - SITA Ground Stations Table 2 - ARINC Ground Stations Table 3 - ENAV Ground Stations Table 4 - Network subscription rate assumptions Table 5 - Aircraft equipage rate assumptions Table 6 - Frequency management assumptions Table 7 - Equipage rate with respect to all simulated flights Table 8 - Alternative communication means assumptions Table 9 - Brief resume of main assumptions Table 10: Summary of parameter settings for simulation stream 01 as discussed previously Table 11: Single Frequency (SF) Scenario compilation Table 12: Summary of parameter settings for simulation stream 02 as discussed previously Table 13: Multi Frequency Scenario compilation Table 14 - Capacity Limitations values, Single-Frequency (SF), optimistic traffic growth, high traffic area Table 15 - TRTD values, Single-Frequency (SF), optimistic traffic growth, high traffic area Table 16 - Overall results, Single-Frequency (SF), optimistic traffic growth, high traffic area Table 17 - Capacity Limitation values, Single-Frequency (SF), optimistic traffic growth with AOC Migration, high traffic area Table 18 - TRTD values, Single-Frequency (SF), optimistic traffic growth with AOC migration, high traffic area Table 19 Overall results, Single-Frequency (SF), optimistic traffic growth with AOC migration, high traffic area Table 20 - Capacity Limitations values, Single-Frequency (SF), median traffic growth, high traffic area Table 21 - TRTD values, Single-Frequency (SF), median traffic growth, high traffic area Table 22 Overall results, Single-Frequency (SF), median traffic growth, high traffic area Table 23 - Capacity Limitation values, Single-Frequency (SF), optimistic traffic growth with AOC Migration, high traffic area Table 24 - TRTD values, Single-Frequency (SF), median traffic growth with AOC migration, high traffic area Table 25 Overall results, Single-Frequency (SF), median traffic growth with AOC migration, high traffic area Table 26 - Capacity Limitation values, Single-Frequency (SF), optimistic traffic growth, medium traffic area Table 27 - TRTD values, Single-Frequency (SF), optimistic traffic growth, medium traffic area Table 28 Overall results, Single-Frequency (SF), optimistic traffic growth, medium traffic area Table 29 - Capacity Limitation values, Single-Frequency (SF), optimistic traffic growth with AOC Migration, medium traffic area Table 30 - TRTD values, Single-Frequency (SF), optimistic traffic growth with AOC Migration, medium traffic area Table 31 Overall results, Single-Frequency (SF), optimistic traffic growth with AOC Migration, medium traffic area Table 32 - Capacity Limitation values, Single-Frequency (SF), median traffic growth, medium traffic area Table 33 - TRTD values, Single-Frequency (SF), median traffic growth, medium traffic area Table 34 Overall results, Single-Frequency (SF), median traffic growth, medium traffic area Table 35 - Capacity Limitation values, Single-Frequency (SF), median traffic growth with AOC Migration, medium traffic area Table 36 -TRTD values, Single-Frequency (SF), median traffic growth with AOC Migration, medium traffic area Table 37 Overall results, Single-Frequency (SF), median traffic growth with AOC Migration, medium traffic area Table 38 - Capacity Limitation values, SF, Multi-Frequencies, optimistic traffic growth, high traffic area Table 39 TRTD values, SF, Multi-Frequencies, optimistic traffic growth, high traffic area Table 40 Overall results, Single-Frequency (SF), optimistic traffic growth, high traffic area of 151

9 Table 41 - Capacity Limitation values, SF, Multi-Frequencies, optimistic traffic growth with AOC migration, high traffic area Table 42 - TRTD values, SF, Multi-Frequencies, optimistic traffic growth with AOC migration, high traffic area Table 43 Overall results, SF, Multi-Frequencies, optimistic traffic growth with AOC migration, high traffic area Table 44 - Capacity Limitation values, SF, Multi-Frequencies, median traffic growth, high traffic area Table 45 - TRTD values, SF, Multi-Frequencies, median traffic growth, high traffic area Table 46 Overall results, SF, Multi-Frequencies, median traffic growth, high traffic area Table 47 - Capacity Limitation values, SF, Multi-Frequencies, median traffic growth with AOC migration, high traffic area Table 48 - TRTD values, SF, Multi-Frequencies, median traffic growth with AOC migration, high traffic area Table 49 Overall results, SF, Multi-Frequencies, median traffic growth with AOC migration, high traffic area Table 50 - Capacity Limitation values, SF, Multi-Frequencies, optimistic traffic growth, medium traffic area Table 51 TRTD values, SF, Multi-Frequencies, optimistic traffic growth, medium traffic area Table 52 Overall results, SF, Multi-Frequencies, optimistic traffic growth, medium traffic area Table 53 - Capacity Limitation values, SF, Multi-Frequencies, optimistic traffic growth with AOC migration, medium traffic area Table 54 - Capacity Limitation values, SF, Multi-Frequencies, optimistic traffic growth with AOC migration, medium traffic area Table 55 Overall results, SF, Multi-Frequencies, optimistic traffic growth with AOC migration, medium traffic area Table 56 - Capacity Limitation values, SF, Multi-Frequencies, median traffic growth, medium traffic area Table 57 - TRTD values, SF, Multi-Frequencies, median traffic growth, medium traffic area Table 58 Overall results, SF, Multi-Frequencies, median traffic growth, medium traffic area Table 59 - Capacity Limitation values, SF, Multi-Frequencies, median traffic growth with AOC migration, medium traffic area Table 60 - TRTD values, SF, Multi-Frequencies, median traffic growth with AOC migration, medium traffic area Table 61 Overall results, SF, Multi-Frequencies, median traffic growth with AOC migration, medium traffic area Table 62: Expected number of flights of mobility scenarios from 2015 to Table 63: Evaluated SITA network relevant for area of interest with high data link usage Table 64: Evaluated ARINC network relevant for area of interest with high data link usage Table 65: Evaluated SITA & ARINC network relevant for area of interest with low data link usage Table 66: Parameters used for link budget calculation Table 67: Frequency Option 1: Single frequency Table 68: Frequency Option 2: Multi frequency deployment with two frequencies Table 69: Frequency Option 3: Multi frequency deployment with three frequencies Table 70: Frequency Option 4: Multi frequency deployment with four frequencies Table 71: ATS Communication profile B2 / B List of figures Figure 1 - Existing and possible future communication systems aligned with SESAR deployment Figure 2 - High Level view of simulation tool chain Figure 3 - Traffic Growth within ECAC Area Figure 4 - European VDL Mode 2 GS topology and simulated reference area Figure 5 - Number of flights within selected areas of interest Figure 6 - Peak instantaneous aircraft count (PIAC) for the ECAC region Figure 7 - ATS and AOC data whole simulation zone (30N010W 60N025E) Optimistic Traffic of 151

10 Figure 8 - AOC percentage (%) whole simulation zone (30N010W 60N025E) Optimistic Traffic Figure 9 - AOC with migration % whole simulation zone (30N010W 60N025E) Optimistic Traffic Figure 10 - ATS and AOC data High Traffic Area (Lille) Optimistic Traffic (ScA) Figure 11 - AOC percentage (%) High Traffic Area (Lille) Optimistic Traffic (ScA) Figure 12 - AOC with migration % High Traffic Area (Lille) Optimistic Traffic (ScA) Figure 13 - ATS and AOC data Medium Traffic Area (Rome) Optimistic Traffic (ScA) Figure 14 - AOC percentage (%) Medium Traffic Area (Rome) Optimistic Traffic (ScA) Figure 15 - AOC with migration % Medium Traffic Area (Rome) Optimistic Traffic (ScA) Figure 16 - ATS and AOC data whole simulation zone (30N010W 60N025E) Median Traffic Figure 17 - AOC percentage (%) whole simulation zone (30N010W 60N025E) Median Traffic. 31 Figure 18 - AOC with migration % whole simulation zone (30N010W 60N025E) Median Traffic Figure 19 - ATS and AOC data High Traffic Area (Lille) Median Traffic Growth (ScC) Figure 20 - AOC percentage (%) High Traffic Area (Lille) Median Traffic Growth (ScC) Figure 21 - AOC with migration % High Traffic Area (Lille) Median Traffic Growth (ScC) Figure 22 - ATS and AOC data Medium Traffic Area (Rome) Median Traffic Growth (ScC) Figure 23 - AOC percentage (%) Medium Traffic Area (Rome) Median Traffic Growth (ScC) Figure 24 - AOC with migration % Medium Traffic Area (Rome) Median Traffic Growth (ScC) Figure 25 - Capacity Limitations, Single-Frequency (SF), optimistic traffic growth, high traffic area Figure 26 - Capacity Limitations, Single-Frequency (SF), optimistic traffic growth with AOC Migration, high traffic area Figure 27 - Capacity Limitations, Single-Frequency (SF), median traffic growth, high traffic area Figure 28 - Capacity Limitations, Single-Frequency (SF), median traffic growth with AOC Migration, high traffic area Figure 29 - Capacity Limitations, Single-Frequency (SF), optimistic traffic growth, medium traffic area Figure 30 - Capacity Limitations, Single-Frequency (SF), optimistic traffic growth with AOC Migration, medium traffic area Figure 31 - Capacity Limitations, Single-Frequency (SF), median traffic growth, medium traffic area 51 Figure 32 - Capacity Limitations, Single-Frequency (SF), median traffic growth with AOC Migration, medium traffic area Figure 33 VDL Mode 2 ground station network performance - Single Frequency scenarios years 2015, 2020, 2025, 2030, 2035 and Figure 34 VDL Mode 2 ground station network performance - Single Frequency scenarios years 2015, 2020, 2025, 2030, 2035 and Figure 35 - Capacity Limitations, SF, Multi-Frequencies, optimistic traffic growth, high traffic area Figure 36 - Capacity Limitations, SF, Multi-Frequencies, optimistic traffic growth with AOC migration, high traffic area Figure 37 - Capacity Limitations, SF, Multi-Frequencies, median traffic growth, high traffic area Figure 38 - Capacity Limitations, SF, Multi-Frequencies, median traffic growth with AOC migration, high traffic area Figure 39 - Capacity Limitations, SF, Multi-Frequencies, optimistic traffic growth, high traffic area Figure 40 - Capacity Limitations, SF, Multi-Frequencies, optimistic traffic growth with AOC migration, medium traffic area Figure 41 - Capacity Limitations, SF, Multi-Frequencies, median traffic growth, medium traffic area. 77 Figure 42 - Capacity Limitations, SF, Multi-Frequencies, median traffic growth with AOC migration, medium traffic area Figure 43: VDL Mode 2 GS network performance Optimistic Traffic - Single- (SF) and Multi- Frequency scenarios: FO2, FO3, FO4, MF4 Year Figure 44: VDL Mode 2 GS network performance Optimistic Traffic - Single- (SF) and Multi- Frequency scenarios: FO2, FO3, FO4, MF4 Year Figure 45: VDL Mode 2 GS network performance Optimistic Traffic - Single- (SF) and Multi- Frequency scenarios: FO2, FO3, FO4, MF4 Year Figure 46: VDL Mode 2 GS network performance Optimistic Traffic - Single- (SF) and Multi- Frequency scenarios: FO2, FO3, FO4, MF4 Year Figure 47: VDL Mode 2 GS network performance Optimistic Traffic - Single- (SF) and Multi- Frequency scenarios: FO2, FO3, FO4, MF4 Year of 151

11 Figure 48: VDL Mode 2 GS network performance Optimistic Traffic - Single- (SF) and Multi- Frequency scenarios: FO2, FO3, FO4, MF4 Year Figure 49: VDL Mode 2 GS network performance Median Traffic - Single- (SF) and Multi-Frequency scenarios: FO2, FO3, FO4, MF4 Year Figure 50: VDL Mode 2 GS network performance Median Traffic - Single- (SF) and Multi-Frequency scenarios: FO2, FO3, FO4, MF4 Year Figure 51: VDL Mode 2 GS network performance Median Traffic - Single- (SF) and Multi-Frequency scenarios: FO2, FO3, FO4, MF4 Year Figure 52: VDL Mode 2 GS network performance Median Traffic - Single- (SF) and Multi-Frequency scenarios: FO2, FO3, FO4, MF4 Year Figure 53: VDL Mode 2 GS network performance Median Traffic - Single- (SF) and Multi-Frequency scenarios: FO2, FO3, FO4, MF4 Year Figure 54 - VDL Mode 2 GS network performance Optimistic Traffic - Single- (SF) and Multi- Frequency scenarios: FO2, FO3, FO4, MF4 Year Figure 55: VDL Mode 2 GS network performance Optimistic Traffic - Single- (SF) and Multi- Frequency scenarios: FO2, FO3, FO4, MF4 Year Figure 56: VDL Mode 2 GS network performance Optimistic Traffic - Single- (SF) and Multi- Frequency scenarios: FO2, FO3, FO4, MF4 Year Figure 57: VDL Mode 2 GS network performance Optimistic Traffic - Single- (SF) and Multi- Frequency scenarios: FO2, FO3, FO4, MF4 Year Figure 58: VDL Mode 2 GS network performance Optimistic Traffic - Single- (SF) and Multi- Frequency scenarios: FO2, FO3, FO4, MF4 Year Figure 59: VDL Mode 2 GS network performance Optimistic Traffic - Single- (SF) and Multi- Frequency scenarios: FO2, FO3, FO4, MF4 Year Figure 60: VDL Mode 2 GS network performance Median Traffic - Single- (SF) and Multi-Frequency scenarios: FO2, FO3, FO4, MF4 Year Figure 61: VDL Mode 2 GS network performance Median Traffic - Single- (SF) and Multi-Frequency scenarios: FO2, FO3, FO4, MF4 Year Figure 62: VDL Mode 2 GS network performance Median Traffic - Single- (SF) and Multi-Frequency scenarios: FO2, FO3, FO4, MF4 Year Figure 63: VDL Mode 2 GS network performance Median Traffic - Single- (SF) and Multi-Frequency scenarios: FO2, FO3, FO4, MF4 Year Figure 64: VDL Mode 2 GS network performance Median Traffic - Single- (SF) and Multi-Frequency scenarios: FO2, FO3, FO4, MF4 Year Figure 65 - Capacity Limitations and TRTD values, SF, Multi-Frequencies, optimistic traffic growth, high traffic area Figure 66 - Overall results, Single-Frequency (SF), optimistic traffic growth, high traffic area Figure 67 - Capacity Limitations and TRTD values, SF, Multi-Frequencies, optimistic traffic growth with AOC migration, high traffic area Figure 68 Overall results, SF, Multi-Frequencies, optimistic traffic growth with AOC migration, high traffic area Figure 69 - Capacity Limitations and TRTD values, SF, Multi-Frequencies, medium traffic growth, high traffic area Figure 70 Overall results, SF, Multi-Frequencies, median traffic growth, high traffic area Figure 71 - Capacity Limitations and TRTD values, SF, Multi-Frequencies, medium traffic growth with AOC migration, high traffic area Figure 72 Overall results, SF, Multi-Frequencies, median traffic growth with AOC migration, high traffic area Figure 73 - High Traffic Area - ARINC Stations Baseline Year 2014/ Figure 74 - High Traffic Area - SITA Stations Baseline Year 2014/ Figure 75 - Capacity Limitations and TRTD values, SF, Multi-Frequencies, optimistic traffic growth, medium traffic area Figure 76 Overall results, SF, Multi-Frequencies, optimistic traffic growth, medium traffic area Figure 77 - Capacity Limitations and TRTD values, SF, Multi-Frequencies, optimistic traffic growth with AOC migration, medium traffic area Figure 78 Overall results, SF, Multi-Frequencies, optimistic traffic growth with AOC migration, medium traffic area Figure 79 - Capacity Limitations and TRTD values, SF, Multi-Frequencies, medium traffic growth, medium traffic area of 151

12 Figure 80 Overall results, SF, Multi-Frequencies, median traffic growth, medium traffic area Figure 81 - Capacity Limitations and TRTD values, SF, Multi-Frequencies, medium traffic growth with AOC migration, medium traffic area Figure 82 Overall results, SF, Multi-Frequencies, median traffic growth with AOC migration, medium traffic area Figure 83 Comparison of Offered Load for various scenarios High traffic vs. Medium traffic area Figure 84 - Medium Traffic Area - ENAV Stations Baseline Year 2014/ Figure 85 - Work Breakdown Structure Figure 86 - GANTT of the project Figure 87: High Level view of simulation tool chain Figure 88: Number of Flights within ECAC Area (peak day 2014; 2015 to 2050 (forecast)) Figure 89: Number of flights on reference day (Aug. 29 th 2014) Figure 90: Simulated area including areas of interest with high and low data traffic Figure 91: Interference Figure 92: Possible trigger events of a simulated flight Figure 93: Application instance and corresponding dialogues Figure 94: Calculation of maximum execution time for a dialogue Figure 95: AOC application message exchanges for different subscriber levels Figure 96 - AOC messages assumed to be exchanged between air and ground for the years 2020 to Figure 97: Markov Model to estimate Technical Round Trip Delay (TRTD) for end-to-end data traffic Figure 98: Simulation protocol stack of VDL Mode 2 performance and capacity study of 151

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14 High quality data communications capabilities, consistent and dependable, are essential enablers to support the implementation of the Single European Sky. The Commission Regulation (EC) No 29/2009, which lays down the requirements on Data Link Services for the Single European Sky (also known as the Data Link Regulation), entered into force on 6 February 2009, became applicable from 7 February 2013 and has subsequently been amended in February Its essential objective was to increase Air Traffic Control capacity by supplementing voice communication by air-ground data link communications. It addresses both the airborne and ground environment with obligations of data link capability for both operators of aircraft and air navigation service providers (ANSP's). The mandated solution is based on VDL mode 2 technology. However, as the use of VDL mode 2 for ACARS over AVLC (AOA) and CPDLC using ATN has become more widespread, certain performance issues were observed that raised concerns on the usability of the system. These concerns led the European Commission to sponsor an EASA investigation into the observed performance issues of this technology. The resulting final report included a ten point Action Plan involving proposals for simulations, performance assessment campaigns, flight trials and deployment planning. SJU launched two studies focussing on VDL Mode 2: the first one the Capacity and Performance Analysis, covered by this document, is dealing with the identification of the time horizon by which VDL Mode 2 should reach its operational limits in Europe, while the second study VDL Mode 2 Measurement, Analysis aims at further analysing the end to end VDL Mode 2 issues experienced today (through lab and flight testing campaigns) and to define potential technical solutions for multifrequency deployment and VDL Mode 2 improvement (protocol optimization, etc). Both studies are complementary coordinated together. The objective of the, presented here, is the identification of the limits of the operational performance of VDL Mode 2 in terms of the Comparison Throughput to Offered Load and its operational usage for ATS purposes. Since the VDL mode 2 technology provides neither the mechanisms for separation of ATS and AOC traffic nor a prioritization scheme for messages with respect to parameters such as safety criticality, it is an accepted consensus that in its current implementation, the technology will at some point reach the limit of its usefulness as a technology from an ATC point of view. Air Traffic Management requires a robust, responsive and trustable datalink technology to help offload traffic off existing voice R/T channels whilst at the same time increasing the overall level of air safety. Currently VDL Mode 2 is operating over one single VHF frequency. From a technical viewpoint, the study sought to reveal whether and if so, at what point, the VDL Mode 2 link, operating on up to 4 VHF frequencies, will reach a performance level commensurate with degradation of service that would objectively be judged as unacceptable for the purposes of the provision of ATC services. The reference document used for this evaluation is CFC/Datalink/PMP "Link DLS CRO Performance Monitoring Requirements", Eurocontrol / Network Manager Directorate, David Isaac, Ed. 1.3, 19 May Looking to a time window from 2015 until 2040 and considering various traffic growth expectations in Europe, the study defined the expected growth of ATS and AOC datalink traffic over that period. Based on in depth modelling of all the Air and Ground components, the simulation determined the VDL Mode 2 performance at the network level and also at each individual Ground Station level. The results enabled conclusions on where and when the VDL Mode 2 link would suffer from quality degradation making it no longer usable especially for ATS purposes. 11 of 151

15 A cross-year analysis has also been detailed, to provide an understanding of how the VDL Mode 2 datalink performances will decrease in comparison to increases of usage. Two areas of interest have been deeply analysed, one representing the busiest airspace in Europe (including London, Paris and Brussels airports and centred on Lille) and an area with medium traffic (centred around Rome). The topology model for this simulation reflects the existing geographical location of the Ground Stations (GS) in Europe. Although, the simulation did not consider the geographical redistribution of the stations, performance details per antenna are provided and the GS that are not performing well can clearly be identified for further investigation. The simulations produced a considerable wealth of technical data, amounting to thousands pages of simulation run results and available on SJU extranet for reference and detailed study. The key findings of the study are that: On the high density area, single frequency implementation is insufficient to service contemporary (2015) bandwidth demand. Progressive extension of VDL2 implementation to the four frequencies already allocated will alleviate the negative trend and postpone the bandwidth exhaustion horizon until 2025, or even later if a suitable network load balancing policy is implemented. On the medium density area, single frequency implementation will support service demand for another few years but not beyond Multi-frequency implementation, utilizing dedicated channels per traffic type (Airport, TMA/En-route) as well as dual squitter solution now pioneered by ENAV will postpone the sunset date to at least 2030, perhaps more if a suitable network load balancing policy is implemented. 12 of 151

16 1 1.1 Purpose of the document In order to anticipate the evolution of the European datalink infrastructure, considering the expected ATS and AOC traffic growth from 2015 until 2040, this study identifies the time horizon by which VDL Mode 2 should reach its operational limits in Europe. Simulation scenarios considered the use of one single frequency as well as up to four frequencies. The aim of this document is to summarize the results of the study and main findings. It provides clear evidences of the identified operational VDL Mode 2 limits, based on results coming from simulations. 1.2 Intended readership The complete ATM community will be interested to check result of this study, so to better understand VDL Mode 2 limits and drive future investments. Institutions can also identify well in advance which appears to be communication future needs for the European airspace, identifying perhaps which may be new technologies that may complement the VDL Mode 2 link and their required performances. 1.3 Inputs from other projects This study has been done on such a way that is really not strictly related to any other study done in the past on this matter. Anyway, in order to identify the criteria that allowed us to determine VDL Mode 2 operational limits; we have used as reference some documents: Link DLS CRO Performance Monitoring Requirements, edition 1.3 Eurocontrol Requirements for monitoring through VDL Mode 2 channels edition, Eurocontrol 1.4 Acronyms and Terminology Term Definition ATM Air Traffic Management ACARS Aircraft Communication Addressing and Reporting System ACSP Air/Ground Communications Service Provider AOC Aeronautical Operational Communications APT Airport Domain ATN aeronautical telecommunications network ATS Air Traffic Services CPDLC Controller-Pilot Datalink Communications CSC Common Signalling Channel DLS Data Link Service ENR En-Route FANS Future Air Navigation System GS VDL Mode 2 Ground Station i4d Initial 4D trajectory LME Link Management Entity MF Multi Frequency OI Operational Improvements PA Provider Abort SESAR Single European Sky ATM Research Programme SESAR Programme The programme which defines the Research and Development activities and Projects for the SJU. SF Single Frequency SJU SESAR Joint Undertaking (Agency of the European Commission) SJU Work Programme The programme which addresses all activities of the SESAR Joint 13 of 151

17 Term Undertaking Agency. TMA Terminal Area TRTD Technical Round Trip Delay USBG University of Salzburg VDL Mode 2 VHF Data Link mode 2 Definition 14 of 151

18 2 Figure 1 - Existing and possible future communication systems aligned with SESAR deployment Figure 1 depicts the SESAR communication infrastructure roadmap which is reflected in the European ATM master plan. This roadmap clearly shows the need to progressively transition from the existing infrastructure towards new datalink solutions. This transition is related to when the current (also called legacy) communication systems will become saturated and new communication systems need to be developed and deployed. Therefore, it is important to identify when data link systems and especially VDL Mode 2 becomes saturated with respect to growing air traffic and new data based operations for ATM. 2.1 Objective of the study The aim of this study is to match aircraft future ATS and AOC traffic requests with foreseen traffic growth, and so to determine when the VDL Mode 2 technology, on monofrequency or multifrequencies, will reach performances that are such to let the link considered as not usable for ATS purposes, that has more stringent requirement than AOC traffic. Simulations provided an incredible amount of data that will be available as annex of this report. Other technical material will be uploaded on SJU extranet. On the main body of this document, main results are summarized, with the help of graphs that give a clear understanding of when the study will foresee this VDL Mode 2 capacity limit. The scope of the study address the capability of mono and multi-frequency VDL Mode 2 to support Datalink services across a number of scenarios. In particular, the analysis determines the capability (capacity and performance) of VDL Mode 2 to support the implementation of evolving datalink services within increasing traffic scenarios. It clearly demonstrated the point at which VDL Mode 2 will no longer be able to support the operational usage of ATS services foreseen within the SESAR Concept. The results enable then the determination of the time horizon by when the introduction of more advanced datalink services will require greater datalink capacity & performance that VDL Mode 2 can offer. This addresses the evolution of traffic and datalink implementations. Datalink services considered are: Existing datalink Services (including Link ) 15 of 151

19 Airline Operational Communication (AOC) ATN Baseline 2 (including initial 4D ) The analysis addresses the time period 2015 through to 2040, with 5 year intervals. The study is giving evidence of technical system loads/key parameters on typical aircraft, operating in dense continental airspace as well as a less busy continental airspace, in line with SJU call for tender requirements and KoM agreement. The following metrics are monitored (always minimum, maximum, average, 95 percentile, 99 percentile, standard deviation, sample count): Application Layer o User Data Rate o User Success Rate o Application Delay o Application Loss / Drop Rate Management Layer (VME) o Logged on Aircraft o Link Establishment Delay o Hand Offs o Broadcast Message Receivers Data Link Services (DLS) o Roundtrip Time o AVLC Frames Medium Access Control (MAC) o MAC Delay o TM2 Occurences o N2 Occurences o T1 Occurences Physical Layer o Channel Occupancy o Offered Load o Throughput o Loss o Transmission Delay o Transmission Distance o Signal Quality Parameter o Collisions o Cause of Failure Taking account of services, link budgets, data volumes and timing, the predicted utilisation analysis clearly show how the evolution and take-up of services will drive utilisation and performance. The analysis indicates clearly when VDL Mode 2 reaches its limitations, the consequence of reaching them and the assumptions being made. 16 of 151

20 3 Within this section we briefly describe the simulation methodology, assumptions and variants taken to assess the VDL Mode 2 capacity breakeven point more detailed descriptions about the simulation modules and parameters used can be found in the annexes. 3.1 Methodology During the introduction of new standards for data communication in aviation (i.e. mainly VDL mode 2, mode 3, and mode 4) a lot of research on the topic of VDL Mode 2 has been published; a paper called characteristics and capacity of VDL Mode 2, 3, and 4 sub-networks 1 gave a good overview of the performance of each of those systems. Also, Eurocontrol conducted a study called VDL Mode 2 Capacity Simulations and published results in late ; USBG was part of this study. Air Traffic Growth Reports Air Traffic in ECAC Area Ground- Station Information Topology Configuration Data Scenario Configuration Application Data Profiles.xls.mdb.txt.txt.txt.xls Mobility Model.xml Topology Model.xml VDL2 Protocol and Channel Simulator.xml.xml.xml.xml.xml.xml D 2.1 D 2.2 D 2.X Seed 1 Seed 2 Seed n.doc VDL2 Report Generator.doc Input Data Final Report D3 MS Word Report D 2.X Figure 2 - High Level view of simulation tool chain 1 Steven C. Bretmersky, Robert R. Murawski, and Vijay K. Konangi. "Characteristics and Capacity of VDL Mode 2, 3, and 4 Subnetworks", Journal of Aerospace Computing, Information, and Communication, Vol. 2, No. 11 (2005), pp /WGM09WP05_VDL2_Capacity%201%20Channel%20Oct04.ppt 17 of 151

21 The approach of the is based on a simulation tool chain where each element provides input to the next element of the chain. Each tool is based on a discrete event based simulation. The first tool (NAVSIM 3 : Air Traffic Calculation) provides the mobility of aircraft of a complete day 4 (i.e. 24 hours). The information of each aircraft is updated in discrete steps of 3 seconds 5. Thereby, important aspects such as position (i.e. longitude, latitude, and altitude), vertical intent, current domain (i.e. APT, TMA, ENR, or ORP), and current sector information are provided. Aircraft are generated for the core area of Europe. The amount of aircraft is extrapolated to the desired scenario (i.e. year and growth scenario). The second tool (VDL Mode 2 Topology Calculation) takes this information and calculates distances of individual aircraft to neighbouring aircraft and visible ground stations. The distances are updated in the same discrete steps as the granularity of the aircraft mobility model. Neighbouring aircraft are all aircraft which are within the radio horizon. The same is true for visible ground-stations. The second tool requires input data such as ground-station positions (latitude, longitude, and altitude), operating frequency, and parameters necessary for link budget calculation such as transmission power or antenna gain. Due to the geographical areas that have been assessed we did not consider any digital elevation model as obstacles are not expected within the evaluated area. The third tool (VDL Mode 2 Protocol and Channel Simulation) takes the mobility, topology, data model, and additional scenario configuration parameters and produces VDL Mode 2 performance data. Each simulation scenario is simulated with multiple different initial seed settings, thus providing confidence intervals for all results. The gained performance data is stored for each seed in a separate xml file. The fourth and final tool (VDL Mode 2 Report Generator) takes all performance data of a single scenario setup and calculates performance figures. These figures are then provided in separate simulation reports. These reports are auto-generated. For concluding comparisons the VDL Mode 2 Report Generator keeps data of interest for the final report. 3 NAVSIM ATM/ATC/CNS Simulation Tool developed by Mobile Communications R&D (MCO) in close co-operation with University of Salzburg (USBG) 4 based on data provided by Eurocontrol/NM (former CFMU) for a reference day (whole ECAC area) 5 might be simulated or derived (interpolated) from time steps of about 1 minute (e.g. Consolidated Position Report (CPR) data) 18 of 151

22 3.2 Assumptions and variants This subsection presents briefly the assumptions and variants taken to compile a representative set of scenarios. The following main simulation variants are taken into account: Air traffic growth Topology Network subscriber rate Simulation time period Equipage rate & data traffic Frequency deployment & management Alternative AOC communications means Assumptions on air traffic growth The air traffic reference (mobility) data has been provided on courtesy by Eurocontrol/NM. The following describes the main characteristics of the reference air traffic data: Reference Day: August 29 th, 2014 (last Friday in August; high/peak day of year 2014) Type of Flights: All IFR Flights (within / to / from) ECAC area on reference day Number of Flights: (within 24 hours) Main data provided for each flight: Figure 3 - Traffic Growth within ECAC Area Callsign / Operator Type of Aircraft Departure and Destination Aerodrome ETD, CTD, ATD (Estimated, Calculated, Actual Time of Departure) ETA, CTA, ATA (Estimated, Calculated, Actual Time of Arrival) Flight Route by Point Coordinates (Latitude, Longitude and Altitude / FL) Flight Route by Air Space Profile (Entry / Exit Time) 19 of 151

23 Figure 3 shows the expected number of flights within the whole ECAC area for the years 2014 to 2050; Scenarios A, C, and D) based on the reference day (August 29 th ) of year While scenario A is assumed to be optimistic, scenario C seems to be a realistic growth model for the coming years. Consequently, we decided to investigate those two scenarios. Variants Baseline Scenario: Year 2015 Air Traffic Growth Scenario A (years 2020, 2025, 2030, 2035 and 2040) Air Traffic Growth Scenario C (years 2020, 2025, 2030, 2035 and 2040) Assumptions on topology Figure 4 - European VDL Mode 2 GS topology and simulated reference area Figure 4 gives an overview of the simulated reference area and the involved data link topology. The black lines indicate simulated air traffic tracks. The red ellipses show the areas of interest for a high data link usage environment (High density area) and a medium data link usage environment (Rome area), respectively. These areas are represented as ellipses as the Mercator projection distorts the circular area of interest with a radius of roughly 150 nautical miles. Each available VDL Mode 2 ground station within the simulated reference area is simulated, however, evaluated are only those which are located within the areas of interests for high and low data link usage, respectively. These ground station positions are represented as orange circles the remaining ground stations are represented as green circles. The areas of Lille and Rome have been selected to represent high and medium data link usage environments, respectively. The area with high air traffic density is the area with roughly 150 nautical miles (nm) radius around Lille, France. All major airports within the capital areas of London, Paris, Brussels and Amsterdam lay within this area. Figure 5 highlights the number of flights within selected 20 of 151

24 areas of interest. This figure clearly shows that the High density area contains most flights across Europe while Rome reflects an area with comparably low air traffic. Figure 5 - Number of flights within selected areas of interest NOTE: Details on the link budget calculation is given in ANNEX B Evaluated ground stations of SITA network in high data link usage environment: Code City Airport Country OWNER FRQ Power AMS7 Amsterdam Schiphol Netherlands SITA 136, W BRU7 Brussels National Belgium SITA 136, W CDG7 Paris CDG France SITA 136, W CDX Paris CDG France SITA 136, W DUS7 Düsseldorf Int l Germany SITA 136, W LCY7 London City UK SITA 136, W Airport LGW7 London Gatwick UK SITA 136,975 5 W LHR7 London Heathrow UK SITA 136, W NWI7 Norwich Int l UK SITA 136, W ORY7 Paris Paris France SITA 136, W Orly PAR7 Paris No France SITA 136, W Airport PARU Paris No France SITA 136, W Airport Table 1 - SITA Ground Stations Evaluated ground stations of ARINC network in high data link usage environment: Code City Airport Country OWNER FRQ Power AMS Amsterdam - Netherlands ARINC 136, W BRU Brussels - Belgium ARINC 136, W CDG Paris - France ARINC 136, W LGW London - UK ARINC 136, W LTN London - UK ARINC 136, W ORY Paris - France ARINC 136, W 21 of 151

25 Code City Airport Country OWNER FRQ Power STN Paris - France ARINC 136, W Table 2 - ARINC Ground Stations NOTE: for all SITA and ARINC VDL Mode 2 ground station antennas a loss attenuation of -3dB is assumed. Evaluated ground stations of SITA/ARINC network in low data link usage environment: Code City Airport Country OWNER FRQ Power Ciampino - Italy ENAV 136, W Fiumicino - Italy ENAV 136, W ATCR-33S Fiumicino - Italy ENAV 136, W SMR-B Napoli - Italy ENAV 136, W Table 3 - ENAV Ground Stations NOTE: for all VDL Mode 2 ground station antennas in Italy a loss attenuation of -4.5 db is assumed. NOTE: In Italy all ground stations are operated by ENAV and have been manufactured by Selex-ES. Those ground stations have adopted criteria named Dual Squitter : The MGS Multi-Squitter is able to manage traffic for all the supported services (ATS and AOC) and for all the aircraft connected regardless the ACSP they belong, on a single VDL Mode 2 radio channel. This will reduce concurrency/collisions and hidden terminals by factor of 2 (more or less). This is achieved thanks to the serialization of the uplinks (ATS, AOC ACSP1 and AOC ACSP2) over the same AVLC links, using a single radio and antenna. The MGS is configured to broadcast different GSIF in using the same VDL Mode 2 radio in order to reach and connect all the aircraft. The simulator has been setup in a way to consider this particular behaviour of ENAV antenna. NOTE: The transmit power level of the VDL Mode 2 ground stations in Italy are either significantly higher (50 Watt for Fiumicino SMR-B and Napoli) compared to the transmit power level of maximum 20 Watt (for ARINC and SITA stations in the high traffic area (Lille)) or are at the low end (10 Watt for Ciampino). Variants No variants for the topology with respect to ground station positions and ground station transmission characteristics have been investigated Assumptions on network subscription rate In Europe SITA and ARINC have different subscriber rates that have been considered in the following way, based on info received by SITA and with the assumptions that the difference between CSP subscriptions will evolve in the future SITA Subscribers 70 % 68 % 66 % 64 % 62 % 60 % ARINC Subscribers 30 % 32 % 34 % 36 % 38 % 40 % Table 4 - Network subscription rate assumptions Table 4 shows an expected slight shift of the market share of about 2% every 5 years up to the year 2040 with a share for SITA and ARINC of 60% and 40% respectively in year Due to the fact that we have not taken additional ARINC ground stations into account, the impact on the study is a further slight degradation of the VDL2 link performance for those stations. The VDL2 performance 22 of 151

26 could be improved - especially for the multi-frequency scenarios - if additional ARINC VDL2 ground stations will be available in the future. Variants No variants for different subscriber rates of ARINC and SITA users have been investigated Assumptions on simulation time period Figure 6 shows the peak instantaneous aircraft count (PIAC) for the ECAC region based on data as described previously. The figure shows maximum aircraft counts for different time frames during the day. It shows that the time frame between 10:00Z and 12:00Z is the one with most aircraft and the one with least variance. Therefore, this time frame has been selected to evaluate the performance and capacity demands of VDL Mode 2. Figure 6 - Peak instantaneous aircraft count (PIAC) for the ECAC region Variants No variants for the evaluation time frame have been investigated Assumptions on aircraft equipage rate The aircraft equipage rate reflects the relative amount of aircraft that are equipped with VDL Mode 2 transceivers. This does not mean that these aircraft are actively using the VDL Mode 2 equipment as communication means. Year VDL Mode 2 80 % 100 % 100 % 100 % 100 % 100 % 100 % 100 % 100 % 100 % EQ Table 5 - Aircraft equipage rate assumptions Variants No variants for the VDL Mode 2 equipage rate have been investigated 23 of 151

27 3.2.6 Assumptions on frequency management Because there is not a standard yet on how to use the 4 frequencies assigned to VDL Mode 2 datalink, the consortium have elaborated options that came from a consultation of experts, as well as workshops done in Eurocontrol. The idea to use the frequencies shared, means based on domains, appears to be the most optimized way to use such frequencies. So, in order to address multi frequency options 4 different possibilities are assumed (together with the option of the single frequency): Channel FRQ Option1 6 FRQ 1 Data traffic carried by frequency Common Signalling Channel (CSC) data Data traffic of aircraft that stay in the airport (APT) domain Data traffic of aircraft that are flying in the TMA/ENR domain Common Signalling Channel (CSC) data FRQ Option 2 7 FRQ 1 Data traffic of aircraft that stay in the airport (APT) domain Data traffic of aircraft that are flying in the TMA/ENR domain FRQ 2 Data traffic of aircraft that stay in the airport (APT) domain Common Signalling Channel (CSC) data FRQ 1 Data traffic of aircraft that stay in the airport (APT) domain FRQ Option 3 8 Data traffic of aircraft that are flying in the TMA/ENR domain FRQ 2 Data traffic of aircraft that stay in the airport (APT) domain FRQ 3 Data traffic of aircraft that are flying in the TMA/ENR domain FRQ Option 4 9 Common Signalling Channel (CSC) data Data traffic of aircraft that are flying in the TMA/ENR domain FRQ 2 Data traffic of aircraft that stay in the airport (APT) domain FRQ 1 Data traffic of aircraft that stay in the airport (APT) domain FRQ 3 Data traffic of aircraft that are flying in the TMA/ENR domain FRQ 4 Data traffic of aircraft that stay in the airport (APT) domain Common Signalling Channel (CSC) data FRQ 1 Data traffic of aircraft that stay in the airport (APT) domain Data traffic of aircraft that are flying in the TMA/ENR domain Data traffic of aircraft that stay in the airport (APT) domain and FRQ Option 5 10 FRQ 2 Data traffic of aircraft that are flying in the TMA/ENR domain Data traffic of aircraft that stay in the airport (APT) domain and FRQ 3 Data traffic of aircraft that are flying in the TMA/ENR domain Data traffic of aircraft that stay in the airport (APT) domain and FRQ 4 Data traffic of aircraft that are flying in the TMA/ENR domain Table 6 - Frequency management assumptions The algorithm for Frequency Options 2 to 4 to select one of the (up to 4) VDL Mode 2 frequencies in the Multi-Frequency (MF) scenarios is implemented as follows: 6 marked as SF (Single Frequency) in the VDL Mode 2 results charts (Chapter 5) 7 marked as FO2 (CSC/APT/TMA/ENR + APT frequency) in the VDL Mode 2 results charts (Chapter 5) 8 marked as FO3 (CSC/APT/TMA/ENR + APT + TMA/ENR frequencies) in results charts (Chapter 5) 9 marked as FO4 (CSC/APT/TMA/ENR + APT + TMA/ENR + APT frequencies) in charts (Chapter 5) 10 marked as MF4 (CSC/APT/TMA/ENR + 3 APT/TMA/ENR frequencies) in results charts (Chapter 5). This option is purely theoretical and is based on observations that University of Salzburg have done during simulation runs. 24 of 151

28 An airborne VDL Mode 2 station (aircraft) always logs into the VDL Mode 2 network via the Common Signalling Channel (CSC; MHz) responding to the periodically transmitted Ground Station Information Frames (GSIF). Then the VDL Mode 2 ground station decides on which frequency the further communication data exchange is carried out. For all aircraft in the airport domain (APT) either the CSC or one of the APT frequencies is chosen. This selection is based on the lowest number of aircraft 11 allocated to a specific ground station. In case that the airborne VDL Mode 2 station (aircraft) is within the TMA/Enroute domain during the initial establishment of the VDL Mode 2 connection via the Common Signalling Channel (CSC) - on request of the VDL Mode 2 ground station the aircraft is either handed over to the VDL Mode 2 frequency foreseen to handle TMA/Enroute data traffic or stays on the CSC. As explained above, this decision is based on the current lowest number of aircraft allocated to the VDL Mode 2 ground stations in question. In case that the domain in which an aircraft is already in (either airport (APT) domain or TMA/Enroute domain) changes, that is either from APT domain to TMA/Enroute domain (initial phase of a flight) or from TMA/Enroute domain to APT domain, the VDL Mode 2 ground station decides whether a handover has to be carried out as follows: Current domain Next domain Current frequency Next frequency Remark APT TMA/ENR CSC CSC or TMA/ENR APT TMA/ENR APT CSC or TMA/ENR TMA/ENR APT CSC CSC or APT APT could be one of two APT frequencies TMA/ENR APT TMA/ENR CSC or APT APT could be one of two APT frequencies The decision which VDL Mode 2 frequency to choose (CSC, APT or TMA/ENR) again depends on the lowest number of aircraft currently allocated to the target (next) frequency. Variants SF Single Frequency Frequency deployment option 1 FO2 Frequency deployment option 2 FO3 Frequency deployment option 3 FO4 Frequency deployment option 4 MF4 Frequency deployment option VDL Mode 2 Multi-Frequency Selection with load balancing In addition to the VDL Mode 2 Multi-Frequency allocation and selection strategy described above, it has also been considered whether a different VDL Mode 2 Multi-Frequency approach would show benefits: This consideration is based on the following: if an aircraft starts from some departure aerodrome and is landing on some destination aerodrome it would carry out communications over VDL Mode 2 during each phase of the flight: Start phase: comms at departure gate, during taxiing and take-off TMA/Enroute phase: during climb phase (TMA), enroute and arrival phase (TMA) 11 further investigations (outside the scope of this study) could use the lowest data traffic load (or other parameters) as a criterion 25 of 151

29 Final phase: during final approach, landing, taxiing and comms at destination gate. By applying any of the VDL Mode 2 Multi-Frequency allocation and selection strategies described above (Frequency Options FO2, FO3 and FO4), the following frequency handovers would 12 occur, during the flight phases mentioned above: Frequency Options FO2: during start phase: possible transition from Common Signalling Channel (CSC) to APT frequency during transition from start phase to TMA/enroute phase: from APT frequency to CSC during transition from TMA/enroute phase to Final phase: from CSC to APT Frequency Options FO3 and FO4: during start phase: possible transition from Common Signalling Channel (CSC) to APT frequency during transition from start phase to TMA/enroute phase: from APT frequency to TMA/ENR frequency during transition from TMA/enroute phase to Final phase: from TMA/ENR frequency to APT frequency Conclusions: for all frequency options FO2, FO3 and FO4 a maximum of 3 frequency hand-offs are likely and will often occur: CSC > APT > TMA/ENR (or CSC) > APT Instead of using the VDL Mode 2 Multi-Frequency selection strategy described above the following Multi-Frequency hand-off strategy (= Frequency Option 5) could be applied: One (instead of up to three) frequency transition (if any) only from the CSC to any other of the available VDL Mode 2 frequencies (based on random selection or load balancing) is carried out; a reasonable number of VDL Mode 2 frequencies (2,3,4 or more 13 ) could be made available, e.g.: MF2: possible transition (if any) from CSC to the other available frequency; MF3: possible transition (if any) from CSC to one of the other two available frequencies; MF4: possible transition (if any) from CSC to one of the other three available frequencies. In addition to the Frequency Options FO2, FO3 and FO4 described above, this Frequency Option 5 (=MF4) with "load balancing" have been simulated for the high traffic area (Lille) and the medium traffic area (Rome) and the promising results are presented and discussed in Chapter 5 of this study ATS datalink program equipage rate Current air traffic control is based on voice exchanges between aircraft crew and air traffic controllers. In order to introduce data link communication for air traffic control purpose, aircraft and air traffic control centres need to be equipped in terms of hardware and software. Currently the vision is that data link will be introduced for air traffic control in 3 phases. These phases are realized through programs called ATN B1, ATN B2, and ATN B3. Assumptions with respect to ATS datalink program: 100 % ground equipage rate. That is, if aircraft are capable to use ATN B 1/2/3 data link message exchanges, they is able to use it at any time. If aircraft are capable to use ATN B2 they will use only the defined set of message for ATN B2. If aircraft are capable to use ATN B3 they will use only the defined set of message for ATN B3. 12 Note: there is always a chance, that a frequency handover does not occur and the VDL Mode 2 airborne station stays on the Common Signalling Channel CSC. 13 Note: Only 4 available VDL Mode 2 frequencies have been simulated; larger numbers of available VDL Mode 2 frequencies (e.g. 6, 8, etc.) could be considered but are outside the scope of this study. 26 of 151

30 The following table indicates the equipage rate with respect to all simulated flights assumed for the different simulated years: ATS ATN B1 80 % 100 % 100 % 100 % 100 % 100 % ATS ATN B2 0 % 0 % 20 % 80 % 100 % 100 % ATS ATN B3 0 % 0 % 0 % 0 % 20 % 80 % Table 7 - Equipage rate with respect to all simulated flights Variants No variants for the VDL Mode 2 datalink program equipage rate have been investigated NOTE: The ATS & AOC communication profiles have been described in the Annex Assumptions on alternative communications means It has to be considered that alternative communications means to VDL Mode 2 may be used for AOC communications in the future. Especially at airports alternatives may arise. So for scenario simulations have been conducted considering this AOC migration as well as no migration at all. The following table lists assumptions for alternative AOC communications means users with respect to all simulated flights. Year AOC APT alternatives 10 % 20 % 30 % 40 % AOC TMA/ENR alternatives 5 % 7,5 % 10 % 20 % Table 8 - Alternative communication means assumptions Variants No AOC communication alternative AOC communication alternative as of the assumption above Assumptions on AOC and ATS Traffic Load On this paragraph, ATS and AOC traffic load is detailed, with the assumptions considered for the 2015 scenario as well as all the futuristic ones. Figure 7 - ATS and AOC data whole simulation zone (30N010W 60N025E) Optimistic Traffic 27 of 151

31 Figure 8 - AOC percentage (%) whole simulation zone (30N010W 60N025E) Optimistic Traffic Figure 9 - AOC with migration % whole simulation zone (30N010W 60N025E) Optimistic Traffic Figure 10 - ATS and AOC data High Traffic Area (Lille) Optimistic Traffic (ScA) 28 of 151

32 Figure 11 - AOC percentage (%) High Traffic Area (Lille) Optimistic Traffic (ScA) Figure 12 - AOC with migration % High Traffic Area (Lille) Optimistic Traffic (ScA) Figure 13 - ATS and AOC data Medium Traffic Area (Rome) Optimistic Traffic (ScA) 29 of 151

33 Figure 14 - AOC percentage (%) Medium Traffic Area (Rome) Optimistic Traffic (ScA) Figure 15 - AOC with migration % Medium Traffic Area (Rome) Optimistic Traffic (ScA) Figure 16 - ATS and AOC data whole simulation zone (30N010W 60N025E) Median Traffic 30 of 151

34 Figure 17 - AOC percentage (%) whole simulation zone (30N010W 60N025E) Median Traffic Figure 18 - AOC with migration % whole simulation zone (30N010W 60N025E) Median Traffic 31 of 151

35 Figure 19 - ATS and AOC data High Traffic Area (Lille) Median Traffic Growth (ScC) Figure 20 - AOC percentage (%) High Traffic Area (Lille) Median Traffic Growth (ScC) Figure 21 - AOC with migration % High Traffic Area (Lille) Median Traffic Growth (ScC) 32 of 151

36 Figure 22 - ATS and AOC data Medium Traffic Area (Rome) Median Traffic Growth (ScC) Figure 23 - AOC percentage (%) Medium Traffic Area (Rome) Median Traffic Growth (ScC) Figure 24 - AOC with migration % Medium Traffic Area (Rome) Median Traffic Growth (ScC) 33 of 151

37 4 A simulation scenario is a combination of the aforementioned models. Thereby, different input parameters may be varied. In this section we elaborate the baseline scenario and scenarios that are conceivable for future deployments. Important aspects of a simulation scenario are: Data load (ATS & AOC): Currently Link applications are being rolled out and are used by isolated aircraft. VDL Mode 2 equipage rate of aircraft: Today not all aircraft are VDL Mode 2 equipped. However, it is anticipated that all aircraft are VDL Mode 2 equipped within the next 5 years. Aircraft using/not using other communication means than VDL mode 2: Today, alternative communication means to VDL Mode 2 are discussed. An airport communication system such as AeroMACS may be introduced at large airports in the upcoming years. Aircraft communication service provider: SITA is the predominant used communication service provider in Europe. However, it is anticipated that ARINC will catch up in the coming years. Deployment scenario: Today, only a single frequency is used for VDL Mode 2 communication. In order to support growing communication demand multi-frequency deployments are conceivable in the future ATN baseline B1 B1 100% B1 100% Equippage rate 80% B2 20% B2 100% B3 20% Traffic growth Real traffic M O M O Frequency Single Multi Single Multi Single Multi VDL Mode 2 100% 100% 90% APT 95% traffic TMA/ENR ATS+AOC traffic SITA 70% SITA 66% SITA 62% ARINC 30% ARINC 34% ARINC 38% Table 9 - Brief resume of main assumptions 100% 70% APT 90% TMA/ENR The simulation scenario setup is organized into 2 main streams Single Frequency Scenarios (evaluations for air traffic growth scenarios A and C) o No alternative AOC communication means considered o Alternative AOC communication means considered Multi Frequency Scenarios (evaluations for air traffic growth scenarios A and C) o 2, 3, and 4 Frequencies no AOC alternative communications means o 2, 3, and 4 Frequencies Alternative AOC alternative communications means considered For all scenarios the application data load is kept stable according to the growth rates for ATS and AOC as described above. Furthermore, the ATS datalink program equipage rate is kept stable. 34 of 151

38 4.1 Simulation Scenarios Single Frequency Year VDL Mode 2 equipped flights 80% 100% 100% 100% 100% 100% ATS ATN B1 equipped flights 80% 100% 100% 100% 100% 100% ATS ATN B2 equipped flight 0% 0% 20% 80% 100% 100% ATS ATN B3 equipped flights 0% 0% 0% 0% 20% 80% AOC APT alternative communication means 0% 0% 0% 0% 0% 0% AOC TMA/ENR alternative communications means 0% 0% 0% 0% 0% 0% SITA subscribers 70% 68% 66% 64% 62% 60% ARINC subscribers 30% 32% 34% 36% 38% 40% Frequency Option Year VDL Mode 2 equipped flights 80% 100% 100% 100% 100% 100% ATS ATN B1 equipped flights 80% 100% 100% 100% 100% 100% ATS ATN B2 equipped flight 0% 0% 20% 80% 100% 100% ATS ATN B3 equipped flights 0% 0% 0% 0% 20% 80% AOC APT alternative communication means 0% 0% 10% 20% 30% 40% AOC TMA/ENR alternative communications means 0% 0% 5% 7,5 % 10% 20% SITA subscribers 70% 68% 66% 64% 62% 60% ARINC subscribers 30% 32% 34% 36% 38% 40% Frequency Option Table 10: Summary of parameter settings for simulation stream 01 as discussed previously. Frequency deployment Topolgoy evaluation Alternative AOC COM Air Traffic Growth Scenario Years Single Frequency deployment option SF High data link usage environment (Lille) Low data link usage environment (Rome) No AOC alternative communications means AOC alternative communications means No AOC alternative communications means AOC alternative communications means Table 11: Single Frequency (SF) Scenario compilation optimistic air traffic growth (ScA) median air traffic growth (ScC) optimistic air traffic growth (ScA) median air traffic growth (ScC) optimistic air traffic growth (ScA) median air traffic growth (ScC) optimistic air traffic growth (ScA) median air traffic growth (ScC) of 151

39 4.2 Simulation Scenarios Multi-Frequency Year VDL Mode 2 equipped flights 80% 100% 100% 100% 100% 100% ATS ATN B1 equipped flights 80% 100% 100% 100% 100% 100% ATS ATN B2 equipped flight 0% 0% 20% 80% 100% 100% ATS ATN B3 equipped flights 0% 0% 0% 0% 20% 80% AOC APT alternative communication means 0% 0% 0% 0% 0% 0% AOC TMA/ENR alternative communications means 0% 0% 0% 0% 0% 0% SITA subscribers 70% 68% 66% 64% 62% 60% ARINC subscribers 30% 32% 34% 36% 38% 40% Frequency Option Year VDL Mode 2 equipped flights 80% 100% 100% 100% 100% 100% ATS ATN B1 equipped flights 80% 100% 100% 100% 100% 100% ATS ATN B2 equipped flight 0% 0% 20% 80% 100% 100% ATS ATN B3 equipped flights 0% 0% 0% 0% 20% 80% AOC APT alternative communication means 0% 0% 10% 20% 30% 40% AOC TMA/ENR alternative communications means 0% 0% 5% 7,5 % 10% 20% SITA subscribers 70% 68% 66% 64% 62% 60% ARINC subscribers 30% 32% 34% 36% 38% 40% Frequency Option Table 12: Summary of parameter settings for simulation stream 02 as discussed previously. Frequency deployment Topolgoy evaluation Alternative AOC COM Air Traffic Growth Scenario Years Multi Frequency deployment options FO2, FO3, FO4, MF4 High data link usage environment (Lille) Low data link usage environment (Rome) Table 13: Multi Frequency Scenario compilation No AOC alternative communications means AOC alternative communications means No AOC alternative communications means AOC alternative communications means optimistic air traffic growth (ScA) median air traffic growth (ScC) optimistic air traffic growth (ScA) median air traffic growth (ScC) optimistic air traffic growth (ScA) median air traffic growth (ScC) optimistic air traffic growth (ScA) median air traffic growth (ScC) NOTE: For reasons of simplicity Table 13 is compressed to one single table. Each deployment option would result in a separate table. However, this also reflects the structure of the presented results later within this document. 36 of 151

40 5 This chapter provides firstly a brief overview of the capacity assessment criteria, which indicate how gained results are interpreted and evaluated. After that, the results for the two simulation streams single-frequency and multi-frequency are elaborated and discussed in detail. 5.1 VDL Mode 2 capacity assessment criteria The very detailed VDL Mode 2 simulations carried out in the context of this study were used as a basis to provide an estimation of the VDL Mode 2 capacity limits. Thereby, single and multi-frequency scenarios were considered 14. For each scenario and for each ground station within the area of interest, important performance parameters were produced. Amongst others, most important parameters are offered load, user data throughput, user data success rate, user data loss rate, round trip delay, medium access control (MAC) delay, transmission delay, and "one-way" uplink/downlink delay (MAC delay + transmission delay). These simulation results were used to conduct a performance analysis to determine the VDL Mode 2 capacity limitations using different deployment options. For each scenario (i.e. deployment option, assumed air traffic growth, and simulated year) a high level overview about the VDL Mode 2 capacity limitation is given. Thereby, two criteria have been defined: 1. VDL Mode 2 capacity limitation VDL Mode 2 Comparison Throughput to Offered Load ATS application performance Technical Round Trip Delay (TRTD) 16 The User Data Offered Load is the amount of data an application wants to transmit and the User Data Throughput is the amount of data that is successfully received by the communication peer 17. The representation of the results is expressed as relative value of User Data Offered Load to User Data Throughput. A coloured categorization has been applied to the results in order to support a quick and comprehensive understanding of the output: >= 95%: very good (dark green) PASS >= 90% up to 95%: good (light green) still PASS 14 In each scenario the default VDL2 parameters were used (e.g. persistence value p = 5/256; no parameter variations were applied; such parameter variations are proposed for further VDL2 optimization studies and evaluations. 15 Offered load corresponds to the load demanded to be transferred over the VDL Mode 2 network. 16 c.f. Link DLS CRO Performance Monitoring Requirements", Eurocontrol / Network Manager Directorate, David Isaac, Ed. 1.3, 19 May Please note that VDL2 messages are still considered to be successfully transmitted, if not more than N2 number of retries (N2 = 6; default value) are used, otherwise the message is considered to be "lost". However the VDL2 message could still be finally successfully delivered to the end user, if end-to-end retransmissions are taken into account (see "Technical Round Trip Delay (TRTD) of ATS/CPDLC messages" below for details). Recently VDL2 measurements were carried out by Eurocontrol (ECTL). The numbers received from ECTL seem to be reasonable. However, it has to be considered that we are stressing the communication system a lot more with almost every aircraft transmitting data messages. This has a significant impact on radio interference and medium access control protocols. It is known that VDL Mode 2 as such is not behaving deterministically - i.e. the more airspace users are utilizing the communication link concurrently the more unpredictable VDL Mode 2 becomes. Additionally the radio propagation model assumes rather worst case than best case assumptions, causing rather more than less interference on the radio channel. In our initial simulation runs we were assuming a free space loss model (which is the absolute worst case) which caused severe message loss due to increased interference. From our point of view the gained simulation results are perfectly in line with the performance of the VDL Mode 2 radio link. 37 of 151

41 >= 85% up to 90%: becoming critical (yellow) BORDERLINE >= 80% up to 85%: critical (orange) definitely BORDERLINE < 80%: (red) - definitely FAIL. The Technical Round Trip Delay (TRTD) of ATS/CPDLC messages has been assessed through a VDL Mode 2 Markov model 18 where two categories were considered i.e. either pass or fail: PASS (green): TRTD 95th percentile <= 16 seconds and TRTD 99th percentile <= 20 sec.; FAIL (red): otherwise The combined overall result of both VDL Mode 2 capacity assessment criteria has been defined as follows: PASS (dark green): Through/Offered >= 90% AND both TRTD percentile target values are fulfilled; almost PASS (light green): Through/Offered >= 90% AND one of the two TRTD percentile target values are fulfilled; FAIL (red): otherwise (i.e. Through/Offered < 90% AND both TRTD percentile values failed. 18 c.f. Annex B for details on the VDL Mode 2 Markov model 38 of 151

42 5.2 Single-Frequency deployment The main conclusion that can be drawn for the single frequency deployment scenarios is that already today and for the near future VDL Mode 2 capacity limits are reached in high density area. That is particularly true, for that area, in combination with high air traffic growth assumptions (ScA), while on medium traffic area the single frequency seems to work fine for 2015 scenario, but not on However, this is also true for all other assumptions taken for simulation scenarios conducted with a single frequency deployment. The single frequency deployment considers a single channel operated at MHz used for both Common Signalling Channel (CSC) and user data exchanges. Details are elaborated in the following sub-chapters according to the structure presented in Table 11. In order to clearly show the results of the study, we will separate high traffic area and medium traffic area, and on each area we will consider optimistic and medium traffic growth, together with or without AOC traffic migration, as defined on Table High traffic area Optimistic air traffic growth (ScA) VDL Mode 2 capacity limitation Figure 25 - Capacity Limitations, Single-Frequency (SF), optimistic traffic growth, high traffic area From this graph it can be concluded that the "offered load" and the "user data throughput" is only close to each other for the baseline year 2014/15. For all further years the gap between the "offered load" and the "user data throughput" increases. As expected, the gap is even larger in this optimistic traffic growth scenario than in the median traffic scenario presented below. This indicates that we have reached the capacity limit for the Single-Frequency scenarios already today or in the near future, respectively. By applying the capacity limitation criteria defined in sub-chapter 5.1 above, we get the following results: Table 14 - Capacity Limitations values, Single-Frequency (SF), optimistic traffic growth, high traffic area The scenario "passed" only for the year 2015, but "failed" for all years at and beyond year of 151

43 ATS application performance For these scenarios the ATS/CPDLC (pass/fail criteria) shows the following results for the Technical Round Trip Delay (TRTD): for the following performance requirements: 95 th percentile target value (max) = 16 seconds 99 th percentile target value (max) = 20 seconds Table 15 - TRTD values, Single-Frequency (SF), optimistic traffic growth, high traffic area From this table it can be concluded that the ATS/CPDLC TRTD requirements are not even fulfilled for the today's (year 2015) scenario 19 ; for all years beyond, the requirements (95 th percentile <= 16 seconds; 99 th percentile <= 20 seconds) are not met ("FAIL"; red). It should also be noted that the capacity limitation expectation values presented above correspond - for all years 2020 to with the ATS/CPDLC Technical Round Trip Delay (TRTD) criteria Combined VDL Mode 2 capacity and ATS application performance results The combined VDL Mode 2 capacity limitations and performance results (see sub-chapter 5.1 above for details) for the investigated scenario are summarized below. Table 16 - Overall results, Single-Frequency (SF), optimistic traffic growth, high traffic area Conclusions for Lille ScA scenario: SF: "FAIL"s already from the year 2015 and all years beyond. The capacity and performance limitations for a single VDL Mode 2 frequency (for the Lille ScA scenario) are reached today. 19 Note: the values for the year 2015 are close to the requirements 40 of 151

44 Optimistic air traffic growth (ScA) alternative AOC COM VDL Mode 2 capacity limitations Figure 26 - Capacity Limitations, Single-Frequency (SF), optimistic traffic growth with AOC Migration, high traffic area In this scenario AOC migration to other communications technologies from the year 2025 onwards is taken into account and simulated. Similar to the optimistic traffic scenario discussed above, from the graph shown here it can be concluded, that from 2025 onwards - as can be expected - the overall traffic load (offered load) increase is smaller compared to the scenario without AOC migration (see figure 8 above), however the VDL Mode 2 capacity limitation is reached already today or in the near future, because the gap between offered load and user data throughput is already significantly high for the year 2020, remains about the same for the years 2025 and 2030 and further increases for the year By applying the capacity limitation criteria defined in sub-chapter 5.1 above, we get the following results: Table 17 - Capacity Limitation values, Single-Frequency (SF), optimistic traffic growth with AOC Migration, high traffic area The scenario "passed" only for the year 2015, but "failed" for all years at and beyond year of 151

45 ATS application performance For those scenarios, the ATS/CPDLC (pass/fail criteria) shows the following results for the Technical Round Trip Delay (TRTD): for the following performance requirements: 95 th percentile target value (max) = 16 seconds 99 th percentile target value (max) = 20 seconds Table 18 - TRTD values, Single-Frequency (SF), optimistic traffic growth with AOC migration, high traffic area Similar to the scenario without AOC migration, from this table it can be concluded that the ATS/CPDLC TRTD requirements are not even fulfilled for the today's (year 2015) scenario 20 ; for all years beyond, the requirements (95 th percentile <= 16 seconds; 99 th percentile <= 20 seconds) are not met ("FAIL"; red) 21. It should also be noted that the capacity limitation expectation values presented above correspond - for all years 2020 to with the ATS/CPDLC Technical Round Trip Delay (TRTD) criteria Combined VDL Mode 2 capacity and ATS application performance results The combined VDL Mode 2 capacity limitations and performance results (see sub-chapter 5.1 above for details) for the investigated scenario are summarized below. Table 19 Overall results, Single-Frequency (SF), optimistic traffic growth with AOC migration, high traffic area Conclusions for Lille ScA AOC Migration scenario: SF: "FAIL"s already from the year 2015 and all years beyond. The capacity and performance limitations for a single VDL Mode 2 frequency (for the Lille ScA AOC migration scenario) are reached today. 20 Note: the values for the year 2015 are close to the requirements 21 Note: A "0" (zero) is shown in the TRTD tables as result from the VDL Mode 2 Markov model, if the average round trip delay (as result from the simulations) is greater than the target values for the TRTD 95 th percentile (16 seconds) or the TRTD 99 th percentile (20 seconds). 42 of 151

46 Median air traffic growth (ScC) VDL Mode 2 capacity limitations Figure 27 - Capacity Limitations, Single-Frequency (SF), median traffic growth, high traffic area From this graph it can be concluded that the "offered load" and the "user data throughput" is close to each other for the baseline year 2014/15 only. Although the data traffic load is lower than in the optimistic traffic scenarios presented above, for all further years the gap between the "offered load" and the "user data throughput" increases. This indicates that we have reached the capacity limit for the Single-Frequency scenarios already today or in the near future. By applying the capacity limitation criteria defined in sub-chapter 5.1 above, we get the following results: Table 20 - Capacity Limitations values, Single-Frequency (SF), median traffic growth, high traffic area The scenario "passed" only for the year 2015, but "failed" for all years at and beyond year of 151

47 ATS application performance For these scenarios the ATS/CPDLC (pass/fail criteria) shows the following results for the Technical Round Trip Delay (TRTD): for the following performance requirements: 95 th percentile target value (max) = 16 seconds 99 th percentile target value (max) = 20 seconds Table 21 - TRTD values, Single-Frequency (SF), median traffic growth, high traffic area From this table it can be concluded that the ATS/CPDLC TRTD requirements are not even fulfilled for the today's (year 2015) scenario 22 ; for all years beyond, the requirements (95 th percentile <= 16 seconds; 99 th percentile <= 20 seconds) are not met ("FAIL"; red). It should also be noted that the capacity limitation expectation values presented above correspond - for all years 2020 to with the ATS/CPDLC Technical Round Trip Delay (TRTD) criteria Combined VDL Mode 2 capacity and ATS application performance results The combined VDL Mode 2 capacity limitations and performance results (see sub-chapter 5.1 above for details) for the investigated scenario are summarized below. Table 22 Overall results, Single-Frequency (SF), median traffic growth, high traffic area Conclusions for Lille ScC scenario: SF: "FAIL"s already from the year 2015 and all years beyond. The capacity and performance limitations for a single VDL Mode 2 frequency (for the Lille ScC scenario) are reached today. 22 Note: the values for the year 2015 are close to the requirements 44 of 151

48 Median air traffic growth (ScC) alternative AOC COM VDL Mode 2 capacity limitations Figure 28 - Capacity Limitations, Single-Frequency (SF), median traffic growth with AOC Migration, high traffic area In this scenario AOC migration to other communications technologies from the year 2025 onwards is taken into account and simulated. From the graph shown here it can be concluded, that from 2025 onwards as can be expected - the overall traffic load (offered load) increase is smaller compared to the scenario without AOC migration (see Figure 27 above), however the VDL Mode 2 capacity limitation is reached already today or in the near future, because the gap between offered load and user data throughput is already significantly high for the year 2020, remains about the same for the years 2025 and 2030 and further increases for years 2035 and By applying the capacity limitation criteria defined in sub-chapter 5.1 above, we get the following results: Table 23 - Capacity Limitation values, Single-Frequency (SF), optimistic traffic growth with AOC Migration, high traffic area The scenario "passed" only for the year 2015, but "failed" for all years at and beyond year of 151

49 ATS application performance For these scenarios the ATS/CPDLC (pass/fail criteria) shows the following results for the Technical Round Trip Delay (TRTD): for the following performance requirements: 95 th percentile target value (max) = 16 seconds 99 th percentile target value (max) = 20 seconds Table 24 - TRTD values, Single-Frequency (SF), median traffic growth with AOC migration, high traffic area Similar to the scenario without AOC migration, from this table it can be concluded that the ATS/CPDLC TRTD requirements are not even fulfilled for the today's (year 2015) scenario 23 ; for all years beyond, the requirements (95 th percentile <= 16 seconds; 99 th percentile <= 20 seconds) are not met ("FAIL"; red). It should also be noted that the capacity limitation expectation values presented above correspond - for all years 2020 to with the ATS/CPDLC Technical Round Trip Delay (TRTD) criteria Combined VDL Mode 2 capacity and ATS application performance results The combined VDL Mode 2 capacity limitations and performance results (see sub-chapter 5.1 above for details) for the investigated scenario are summarized below. Table 25 Overall results, Single-Frequency (SF), median traffic growth with AOC migration, high traffic area Conclusions for Lille ScC AOC migration scenario: SF: "FAIL"s already from the year 2015 and all years beyond. The capacity and performance limitations for a single VDL Mode 2 frequency (for the Lille ScC AOC migration scenario) are reached today. 23 Note: the values for the year 2015 are close to the requirements 46 of 151

50 5.2.2 Medium traffic area At least from the year 2025/2030 onwards the VDL Mode 2 capacity limits for the medium traffic area (Rome), assuming a median traffic growth (scenario ScC), is reached. Considering a high traffic growth (scenario ScA) this VDL Mode 2 capacity limitation is reached already for the year 2020 onwards. The reasons for these limitations are outlined in the paragraphs below Optimistic air traffic growth (ScA) VDL Mode 2 Capacity Limitations Figure 29 - Capacity Limitations, Single-Frequency (SF), optimistic traffic growth, medium traffic area From this graph it can be concluded that the "offered load" and the "user data throughput" is only close to each other for the baseline year 2014/15. For all further years the gap between the "offered load" and the "user data throughput" increases. As expected, the gap is even larger in this optimistic traffic growth scenario than in the median traffic scenario presented below. This indicates that we have reached the capacity limit for the Single-Frequency scenarios already today or in the near future. By applying the capacity limitation criteria defined in sub-chapter 5.1 above, we get the following results: Table 26 - Capacity Limitation values, Single-Frequency (SF), optimistic traffic growth, medium traffic area The scenario "passed" only for the year 2015, but "failed" for all years at and beyond year of 151

51 ATS application performance For these scenarios the ATS/CPDLC (pass/fail criteria) shows the following results for the Technical Round Trip Delay (TRTD): for the following performance requirements: 95 th percentile target value (max) = 16 seconds 99 th percentile target value (max) = 20 seconds Table 27 - TRTD values, Single-Frequency (SF), optimistic traffic growth, medium traffic area From this table it can be concluded that the ATS/CPDLC TRTD requirements are fulfilled ("PASS"; green) for the today's (year 2015) scenario only, but for all years beyond, the requirements (95 th percentile <= 16 seconds; 99 th percentile <= 20 seconds) are not met ("FAIL"; red). It should also be noted that the capacity limitation expectation values presented above correspond - for all years 2015 to with the ATS/CPDLC Technical Round Trip Delay (TRTD) criteria Combined VDL Mode 2 capacity and ATS application performance results The combined VDL Mode 2 capacity limitations and performance results (see sub-chapter 5.1 above for details) for the investigated scenario are summarized below. Table 28 Overall results, Single-Frequency (SF), optimistic traffic growth, medium traffic area Conclusions for Rome ScA scenario: SF: "PASS" only for the year 2015; "FAIL"s from the year 2020 and all years beyond. The capacity and performance limitations for a single VDL Mode 2 frequency (for the Rome ScA scenario) will be reached before the year of 151

52 Optimistic air traffic growth alternative AOC COM VDL Mode 2 Capacity Limitations Figure 30 - Capacity Limitations, Single-Frequency (SF), optimistic traffic growth with AOC Migration, medium traffic area Similar to the optimistic traffic scenario discussed above, from the graph shown here it can be concluded, that from 2025 onwards as can be expected - the overall traffic load (offered load) increase is smaller compared to the scenario without AOC migration (see Figure 35 above), however the VDL Mode 2 capacity limitation is reached already today or in the near future, because the gap between offered load and user data throughput is already significantly high for the year 2020, remains about the same for the years 2025 and 2030 and further increases for the year By applying the capacity limitation criteria defined in sub-chapter 5.1 above, we get the following results: Table 29 - Capacity Limitation values, Single-Frequency (SF), optimistic traffic growth with AOC Migration, medium traffic area The scenario "passed" only for the year 2015, but "failed" for all years at and beyond year of 151

53 ATS application performance For these scenarios the ATS/CPDLC (pass/fail criteria) shows the following results for the Technical Round Trip Delay (TRTD): for the following performance requirements: 95 th percentile target value (max) = 16 seconds 99 th percentile target value (max) = 20 seconds Table 30 - TRTD values, Single-Frequency (SF), optimistic traffic growth with AOC Migration, medium traffic area From this table it can be concluded that the ATS/CPDLC TRTD requirements are fulfilled ("PASS"; green) for the today's (year 2015) scenario only, but for all years beyond, the requirements (95 th percentile <= 16 seconds; 99 th percentile <= 20 seconds) are not met ("FAIL"; red). It should also be noted that the capacity limitation expectation values presented above correspond - for all years 2015 to with the ATS/CPDLC Technical Round Trip Delay (TRTD) criteria Combined VDL Mode 2 capacity and ATS application performance results The combined VDL Mode 2 capacity limitations and performance results (see sub-chapter 5.1 above for details) for the investigated scenario are summarized below. Table 31 Overall results, Single-Frequency (SF), optimistic traffic growth with AOC Migration, medium traffic area Conclusions for Rome ScA AOC migration scenario: SF: "PASS" only for the year 2015; "FAIL"s from the year 2020 and all years beyond. The capacity and performance limitations for a single VDL Mode 2 frequency (for the Rome ScA AOC migration scenario) will be reached before the year of 151

54 Median air traffic growth (ScC) VDL Mode 2 capacity limitations Figure 31 - Capacity Limitations, Single-Frequency (SF), median traffic growth, medium traffic area From this graph it can be concluded that the "offered load" and the "user data throughput" is close to each other for the baseline year 2014/15 only. The gap increases for the year 2020, however, even for the year 2025, it shows only a small gap; from the year 2030 onwards it shows a significant gap between the "offered load" and the "user data throughput" and for all further years this gap increases. Therefore it should be concluded that from the year 2030 onwards the capacity limitation is reached. In general, as can be expected, the results for the high traffic area (Lille) show a larger gap between "offered load" and "user data throughput" than for the medium traffic area (Rome). Table 32 - Capacity Limitation values, Single-Frequency (SF), median traffic growth, medium traffic area The scenario "passed" only for the year 2015, but "failed" for all years at and beyond year of 151

55 ATS application performance For these scenarios the ATS/CPDLC (pass/fail criteria) shows the following results for the Technical Round Trip Delay (TRTD): for the following performance requirements: 95 th percentile target value (max) = 16 seconds 99 th percentile target value (max) = 20 seconds Table 33 - TRTD values, Single-Frequency (SF), median traffic growth, medium traffic area From this table it can be concluded that the ATS/CPDLC TRTD requirements are fulfilled ("PASS"; green) for the today's (year 2015) scenario only, but for all years beyond, the requirements (95 th percentile <= 16 seconds; 99 th percentile <= 20 seconds) are not met ("FAIL"; red). It should also be noted that the capacity limitation expectation values presented above correspond - for all years 2015 to with the ATS/CPDLC Technical Round Trip Delay (TRTD) criteria Combined VDL Mode 2 capacity and ATS application performance results The combined VDL Mode 2 capacity limitations and performance results (see sub-chapter 5.1 above for details) for the investigated scenario are summarized below. Table 34 Overall results, Single-Frequency (SF), median traffic growth, medium traffic area Conclusions for Rome ScC scenario: SF: "PASS" only for the year 2015; "FAIL"s from the year 2020 and all years beyond. The capacity and performance limitations for a single VDL Mode 2 frequency (for the Rome ScC scenario) will be reached before the year of 151

56 Median air traffic growth (ScC) alternative AOC COM VDL Mode 2 capacity limitations Figure 32 - Capacity Limitations, Single-Frequency (SF), median traffic growth with AOC Migration, medium traffic area In this scenario AOC migration to other communications technologies from the year 2025 onwards is taken into account and simulated. From the graph shown here it can be concluded, that from 2025 onwards as can be expected - the overall traffic load (offered load) increase is smaller compared to the scenario without AOC migration (see Figure 31 above), however the VDL Mode 2 capacity limitation is reached already today or in the near future, because the gap between offered load and user data throughput is already significantly high for the year 2020, remains about the same for the years 2025 and 2030 and further increases until the year By applying the capacity limitation criteria defined in sub-chapter 5.1 above, we get the following results: Table 35 - Capacity Limitation values, Single-Frequency (SF), median traffic growth with AOC Migration, medium traffic area The scenario "passed" only for the year 2015, but "failed" for all years at and beyond year of 151

57 ATS application performance For these scenarios the ATS/CPDLC (pass/fail criteria) shows the following results for the Technical Round Trip Delay (TRTD): for the following performance requirements: 95 th percentile target value (max) = 16 seconds 99 th percentile target value (max) = 20 seconds Table 36 -TRTD values, Single-Frequency (SF), median traffic growth with AOC Migration, medium traffic area From this table it can be concluded that the ATS/CPDLC TRTD requirements are fulfilled ("PASS"; green) for the today's (year 2015) scenario only, but for all years beyond, the requirements (95 th percentile <= 16 seconds; 99 th percentile <= 20 seconds) are not met ("FAIL"; red). It should also be noted that the capacity limitation expectation values presented above correspond - for all years 2015 to with the ATS/CPDLC Technical Round Trip Delay (TRTD) criteria Combined VDL Mode 2 capacity and ATS application performance results The combined VDL Mode 2 capacity limitations and performance results (see sub-chapter 5.1 above for details) for the investigated scenario are summarized below. Table 37 Overall results, Single-Frequency (SF), median traffic growth with AOC Migration, medium traffic area Conclusions for Rome ScC AOC migration scenario: SF: "PASS" only for the year 2015; "FAIL"s from the year 2020 and all years beyond. The capacity and performance limitations for a single VDL Mode 2 frequency (for the Rome ScC AOC migration scenario) will be reached before the year of 151

58 Single Frequency deployment summary Based on the two assessment criteria, namely the VDL Mode 2 capacity limitation and the ATS application performance the Single Frequency deployment option clearly shows that VDL Mode 2 capacity limits do not support a proper ATS communication performance right from the beginning. This is particularly true for the High traffic area; however, it is also true for the Medium traffic area. The High traffic area provides a solid VDL Mode 2 communication performance for the baseline scenario. However, this performance does not suffice to provide the required ATS application performance. Consequently it is no surprise that all subsequent years do not fulfil any of the desired performance criteria. A similar picture results for the Medium traffic area. The figures indicate a good VDL Mode 2 communication performance that is sufficient to support ATS application performance requirements for the baseline scenario. Nevertheless, all sub-sequent years do not support any of the required performance figures considering single frequency deployment. As such the concluding remark for single frequency deployments is that a quick adoption to multifrequency deployments is necessary in order to achieve the desired ATS application performance High traffic area The following contains a graphical overview showing the main capacity performance of the various VDL Mode 2 ground stations forming the VDL Mode 2 network. The capacity limitation results of the detailed VDL Mode 2 simulations are expressed as relative value of User Data Offered Load to User Data Throughput. A coloured categorization has been applied to the results in order to support a quick and comprehensive understanding of the output: In the maps below, each VDL Mode 2 ground station is marked with a circle, which indicates the performance of the specific station: >= 95%: very good (dark green) PASS >= 90% up to 95%: good (light green) still PASS >= 85% up to 90%: becoming critical (yellow) BORDERLINE >= 80% up to 85%: critical (orange) definitely BORDERLINE < 80%: (red) - definitely FAIL. 55 of 151

59 Figure 33 VDL Mode 2 ground station network performance - Single Frequency scenarios years 2015, 2020, 2025, 2030, 2035 and 2040

60 Medium traffic area The following contains a graphical overview showing the main capacity performance of the various VDL Mode 2 ground stations forming the VDL Mode 2 network. The capacity limitation results of the detailed VDL Mode 2 simulations are expressed as relative value of User Data Offered Load to User Data Throughput. A coloured categorization has been applied to the results in order to support a quick and comprehensive understanding of the output: In the maps below, each VDL Mode 2 ground station is marked with a circle, which indicates the performance of the specific station: >= 95%: very good (dark green) PASS >= 90% up to 95%: good (light green) still PASS >= 85% up to 90%: becoming critical (yellow) BORDERLINE >= 80% up to 85%: critical (orange) definitely BORDERLINE < 80%: (red) - definitely FAIL.

61 Figure 34 VDL Mode 2 ground station network performance - Single Frequency scenarios years 2015, 2020, 2025, 2030, 2035 and 2040

62 5.3 Multi-Frequency deployment In order to clearly show the results of the study, we will separate high traffic area and medium traffic area, and on each area we will consider optimistic and medium traffic growth, together with or without AOC traffic migration, as defined on Table High traffic area Optimistic air traffic growth (ScA) VDL Mode 2 capacity limitations Figure 35 - Capacity Limitations, SF, Multi-Frequencies, optimistic traffic growth, high traffic area In this scenario - which is the highest data traffic scenario in the whole context of this study - user data throughput results for the Multi-Frequency Options FO2, FO3, FO4 and MF4 (explained in detail in sub-chapter 0) are considered and compared to the offered load and the Single-Frequency (SF) option. By applying any of the Multi-Frequency Options (FO2, FO3, FO4 and MF4), reaching VDL Mode 2 capacity limitations can be avoided today and in the near future. As can be concluded from this graph (Figure 357 above) and the capacity limitation value table below, although one additional frequency (Frequency options FO2) shows some advantage over the Single- Frequency (SF) scenario, this additional frequency cannot compensate for the significant increase of data traffic estimated for the year 2020 and beyond. Although two additional frequencies, i.e. a total of 3 available VDL Mode 2 frequencies (FO3) show as can be expected further advantages for this highest data traffic scenario, also FO3 seems to be insufficient already for the year 2020 and certainly for the years beyond. However when applying a total of 4 VDL Mode 2 frequencies (FO4 and MF4), VDL Mode 2 capacity limitations are not expected before the year 2030, but it should be noted that TRTD requirements are not met (at least) for the year 2020 onwards. The proposed Frequency Option 5 (=MF4) with load balancing shows a further advantage over option FO4, such that 4 VDL Mode 2 frequency options could be sufficient up to the year 2035, but it should be noted that TRTD requirements are not met (at least) for the year 2025 onwards.

63 Therefore it can be concluded, that by applying the options FO4 or MF4 option, reaching VDL Mode 2 capacity limitations can be avoided at least up to the year 2020/2025. It is recommended to investigate further in these promising results obtained when applying Multi- Frequency option MF4. By applying the capacity limitation criteria defined in sub-chapter 5.1 above, we get the following results: Table 38 - Capacity Limitation values, SF, Multi-Frequencies, optimistic traffic growth, high traffic area Conclusions for Lille ScA scenario: SF: "PASS" only for the year 2015 (but refer also to the TRTD values below), "FAIL" for all years at and beyond year FO2: "PASS" only for the year 2015 (but refer also to the TRTD values below), "BORDERLINE" for the year 2020 and "FAIL" for all years at and beyond the year FO3: "PASS" only for the year 2015 (but refer also to the TRTD values below), "BORDERLINE" for the years 2020 and 2025 and "FAIL" for all years at and beyond the year FO4: "PASS" for the years 2015 and 2020 (but refer also to the TRTD values below), "PASS" for the years 2025 and 2030 (but "FAIL" with regard to the TRTD values below), "BORDERLINE" for the year 2035 and "FAIL" for year MF4: "PASS" for the years 2015 to 2025 (but refer also to the TRTD values below), "PASS" for the years 2030 and 2035 (but "FAIL" with regard to the TRTD values below), and "BORDERLINE" for the year ATS application performance For these scenarios the ATS/CPDLC (pass/fail criteria) shows the following results for the Technical Round Trip Delay (TRTD): for the following performance requirements: 95 th percentile target value (max) = 16 seconds 99 th percentile target value (max) = 20 seconds Table 39 TRTD values, SF, Multi-Frequencies, optimistic traffic growth, high traffic area 60 of 151

64 Conclusions for Lille ScA scenario: The Single-Frequency (SF) option "FAIL"s for all years 2015 and beyond. All Multi-Frequency Options (FO2, FO3, FO4 and MF4) "PASS" for the year 2015, but FO2 and FO3 "FAIL" for all years at and beyond year FO4: "PASS" for the years 2015, 2020; almost 24 "PASS" for the years 2025; but "FAIL" for the years at and beyond year MF4: "PASS" for the years 2015 up to 2025, but "FAIL"s for the year It should also be noted, that the ATS application performance results based on the TRTD values correspond well with the capacity limitation results presented above (except for SF for year 2015) Combined VDL Mode 2 capacity and ATS application performance results The combined VDL Mode 2 capacity limitations and performance results (see sub-chapter 5.1 above for details) for the investigated scenario are summarized below. Table 40 Overall results, Single-Frequency (SF), optimistic traffic growth, high traffic area Conclusions for Lille ScA scenario: SF: "FAIL"s already from the year 2015 and all years beyond. FO2, FO3: "PASS" for the year 2015 only; "FAIL" from the year 2020 onwards. FO4: "PASS" for the years 2015 and 2020; almost "PASS" for the years 2025 and 2030; "FAIL" from the year 2035 onwards. MF4: "PASS" for the year 2015 up to 2025; almost "PASS" for the years 2030 and 2035; "FAIL" for the year Note: For this highest data traffic scenario, more than 4 VDL Mode 2 frequencies will be required from the year 2030 onwards. 24 The 99 th percentile with a value of 98.3% is close to the target value of 99%. 61 of 151

65 Optimistic air traffic growth alternative AOC COM VDL Mode 2 capacity limitations Figure 36 - Capacity Limitations, SF, Multi-Frequencies, optimistic traffic growth with AOC migration, high traffic area In this scenario user data throughput results for the Multi-Frequency Options FO2, FO3, FO4 and MF4 (explained in detail in sub-chapter 0) are considered and compared to the offered load and the Single-Frequency (SF) option. By applying any of the Multi-Frequency Options (FO2 FO and MF4), reaching VDL Mode 2 capacity limitations can be avoided today and in the near future. As can be concluded from this graph (Figure 18 above) and the capacity limitation value table below, although one additional frequency (Frequency options FO2) shows some advantage over the Single- Frequency (SF) scenario, this additional frequency cannot compensate for the significant increase of data traffic estimated for the year 2020 and beyond. Although two additional frequencies, i.e. a total of 3 available VDL Mode 2 frequencies (FO3) show as can be expected further advantages for this scenario, also FO3 seems to be insufficient already for the year 2020 and certainly for the years beyond. However when applying a total of 4 VDL Mode 2 frequencies (FO4 and MF4), VDL Mode 2 capacity limitations are not expected before the year 2030, but it should be noted that TRTD requirements are not met (at least) for the year 2020 onwards. The proposed Frequency Option 5 (=MF4) with load balancing shows a further advantage over option FO4, such that 4 VDL Mode 2 frequency options could be sufficient up to the year 2035, but it should be noted that TRTD requirements are not met (at least) for the year 2020 (FO4) or 2030 (MF4) onwards. Therefore it can be concluded, that by applying the multi-frequency options FO4 or MF4, reaching VDL Mode 2 capacity limitations can be avoided at least up to the year 2025/2030. It is recommended to investigate further in these promising results obtained when applying Multi- Frequency option MF4. 62 of 151

66 By applying the capacity limitation criteria defined in sub-chapter 5.1 above, we get the following results: Table 41 - Capacity Limitation values, SF, Multi-Frequencies, optimistic traffic growth with AOC migration, high traffic area Conclusions for Lille ScA with AOC migration scenario: SF: "PASS" only for the year 2015 (but refer also to the TRTD values below), "FAIL" for all years at and beyond year FO2: definitely "PASS" only for the year 2015 (TRTD requirements are also fulfilled), but "BORDERLINE" for the year 2020 and "FAIL" for all years at and beyond the year FO3: definitely "PASS" only for the year 2015 (TRTD requirements are also fulfilled), "BORDERLINE" for the years 2020 to 2030 and "FAIL" for all years at and beyond the year FO4: definitely "PASS" for the years 2015 and 2020 (TRTD requirements are also fulfilled), "PASS" for the years 2025 and 2030 (TRTD requirements are also almost fulfilled), but "BORDERLINE" for the years 2035 and MF4: definitely "PASS" for the years 2015 up to year 2030 (TRTD requirements are also fulfilled), and "PASS" for the years 2035 and 2040 (TRTD requirements are also almost fulfilled) ATS application performance For these scenarios the ATS/CPDLC (pass/fail criteria) shows the following results for the Technical Round Trip Delay (TRTD): for the following performance requirements: 95 th percentile target value (max) = 16 seconds 99 th percentile target value (max) = 20 seconds Table 42 - TRTD values, SF, Multi-Frequencies, optimistic traffic growth with AOC migration, high traffic area 63 of 151

67 Conclusions for Lille ScA with AOC migration scenario: The Single-Frequency (SF) option "FAIL"s for all years 2015 and beyond. All Multi-Frequency Options (FO2, FO3, FO4 and MF4) "PASS" for the year 2015, but FO2 and FO3 "FAIL" for all years at and beyond year FO4: "PASS" for the years 2015 and 2020; almost 25 "PASS" for the years 2025 and 2030; but "FAIL" for the years at and beyond year MF4: "PASS" for the years 2015 up to 2035; almost 26 "PASS" for the years 2035 and Combined VDL Mode 2 capacity and ATS application performance results The combined VDL Mode 2 capacity limitations and performance results (see sub-chapter 5.1 above for details) for the investigated scenario are summarized below. Table 43 Overall results, SF, Multi-Frequencies, optimistic traffic growth with AOC migration, high traffic area Conclusions for Lille ScA - Migration scenario: SF: "FAIL"s already from the year 2015 and all years beyond. FO2, FO3: "PASS" for the year 2015 only; "FAIL" from the year 2020 onwards. FO4: "PASS" for the years 2015 and 2020; almost "PASS" for the years 2025 and 2030; "FAIL" from the year 2035 onwards. MF4: "PASS" for the year 2015 up to 2030; almost "PASS" for the years 2035 and The scenario shows advantages with regard to the MF4 frequency option compared to the Lille ScA scenario without AOC migration: MF4 can fulfil the requirements up to the year Note: for this scenario, more than 4 VDL Mode 2 frequencies will be required from the year 2035 onwards. 25 The 99 th percentile with values of 98.8% and 97.7% is close to the target value of 99%. 26 The 99 th percentile with values of 98.4% and 98.0% is close to the target value of 99%. 64 of 151

68 Median air traffic growth (ScC) VDL Mode 2 capacity limitations Figure 37 - Capacity Limitations, SF, Multi-Frequencies, median traffic growth, high traffic area In this scenario user data throughput results for the Multi-Frequency Options FO2, FO3, FO4 and MF4 (explained in detail in sub-chapter 0) are considered and compared to the offered load and the Single-Frequency (SF) option. By applying any of the Multi-Frequency Options (FO2 FO and MF4), reaching VDL Mode 2 capacity limitations can be avoided today and in the near future. As can be concluded from this graph (Figure 37 above) and the capacity limitation value table below, although one additional frequency (Frequency options FO2) shows some advantage over the Single- Frequency (SF) scenario, this additional frequency cannot compensate for the significant increase of data traffic estimated for the year 2020 and beyond. Although two additional frequencies, i.e. a total of 3 available VDL Mode 2 frequencies (FO3) show as can be expected further advantages for this scenario, also FO3 seems to be insufficient already for the year 2020 and certainly for the years beyond. However when applying a total of 4 VDL Mode 2 frequencies (FO4 and MF4), VDL Mode 2 capacity limitations are not expected before the year 2030, but it should be noted that TRTD requirements are not met (at least) for the year 2020 onwards. The proposed Frequency Option 5 (=MF4) with load balancing shows a further advantage over option FO4, such that 4 VDL Mode 2 frequency options could be sufficient up to the year 2030, but it should be noted that TRTD requirements are not met (at least) for the year 2020 (FO4) or 2035 (MF4) onwards. Therefore it can be concluded, that by applying the multi-frequency options FO4 or MF4, reaching VDL Mode 2 capacity limitations can be avoided at least up to the year 2025/2030. It is recommended to investigate further in these promising results obtained when applying Multi- Frequency option MF4. 65 of 151

69 By applying the capacity limitation criteria defined in sub-chapter 5.1 above, we get the following results: Table 44 - Capacity Limitation values, SF, Multi-Frequencies, median traffic growth, high traffic area Conclusions for Lille ScC scenario: SF: "PASS" only for the year 2015 (but refer also to the TRTD values below), "FAIL" for all years at and beyond year FO2: definitely "PASS" only for the year 2015 (TRTD requirements are also fulfilled), but "BORDERLINE" for the year 2020 and "FAIL" for all years at and beyond the year FO3: definitely "PASS" only for the year 2015 (TRTD requirements are also fulfilled), "BORDERLINE" for the years 2020 to 2030 and "FAIL" for all years at and beyond the year FO4: definitely "PASS" for the years 2015 and 2020 (TRTD requirements are also fulfilled), "PASS" for the years 2025 and 2030 (TRTD requirements are also almost fulfilled), but "BORDERLINE" for the years 2035 and MF4: definitely "PASS" for the years 2015 up to year 2030 (TRTD requirements are also fulfilled), and "PASS" for the years 2035 and 2040 (TRTD requirements are also almost fulfilled) ATS application performance For these scenarios the ATS/CPDLC (pass/fail criteria) shows the following results for the Technical Round Trip Delay (TRTD): for the following performance requirements: 95 th percentile target value (max) = 16 seconds 99 th percentile target value (max) = 20 seconds Table 45 - TRTD values, SF, Multi-Frequencies, median traffic growth, high traffic area 66 of 151

70 Conclusions for Lille ScC scenario: The Single-Frequency (SF) option "FAIL"s for all years 2015 and beyond. All Multi-Frequency Options (FO2, FO3, FO4 and MF4) "PASS" for the year 2015, but FO2 and FO3 "FAIL" for all years at and beyond year FO4: "PASS" for the years 2015 and 2020; almost 27 "PASS" for the years 2025 and 2030; but "FAIL" for the years at and beyond year MF4: "PASS" for the years 2015 up to 2030; almost 28 "PASS" for the years 2035 and Combined VDL Mode 2 capacity and ATS application performance results The combined VDL Mode 2 capacity limitations and performance results (see sub-chapter 5.1 above for details) for the investigated scenario are summarized below. Table 46 Overall results, SF, Multi-Frequencies, median traffic growth, high traffic area Conclusions for Lille ScC - scenario: SF: "FAIL"s already from the year 2015 and all years beyond. FO2, FO3: "PASS" for the year 2015 only; "FAIL" from the year 2020 onwards. FO4: "PASS" for the years 2015 and 2020; almost "PASS" for the years 2025 and 2030; "FAIL" from the year 2035 onwards. MF4: "PASS" for the year 2015 up to 2030; almost "PASS" for the years 2035 and The overall VDL Mode 2 capacity limitations and performance results are identical to the Lille ScA with AOC migration scenario. The scenario shows advantages with regard to the MF4 frequency option compared to the Lille ScA scenario without AOC migration: MF4 can fulfil the requirements up to the year Note: for this scenario, more than 4 VDL Mode 2 frequencies will be required from the year 2035 onwards. 27 The 99 th percentile with values of 98.7% and 97.6% is close to the target value of 99%. 28 The 99 th percentile with values of 98.1% and 97.1% is close to the target value of 99%. 67 of 151

71 Median air traffic growth (ScC) alternative AOC COM VDL Mode 2 capacity limitations Figure 38 - Capacity Limitations, SF, Multi-Frequencies, median traffic growth with AOC migration, high traffic area In this scenario user data throughput results for the Multi-Frequency Options FO2, FO3, FO4 and MF4 (explained in detail in sub-chapter 0) are considered and compared to the offered load and the Single-Frequency (SF) option. By applying any of the Multi-Frequency Options (FO2 FO and MF4), reaching VDL Mode 2 capacity limitations can be avoided today and in the near future. As can be concluded from this graph (Figure 20 above) and the capacity limitation value table below, although one additional frequency (Frequency options FO2) shows some advantage over the Single- Frequency (SF) scenario, this additional frequency cannot compensate for the significant increase of data traffic estimated for the year 2020 and beyond. Although two additional frequencies, i.e. a total of 3 available VDL Mode 2 frequencies (FO3) show as can be expected further advantages for this scenario, also FO3 seems to be insufficient already for the year 2020 and certainly for the years beyond. However when applying a total of 4 VDL Mode 2 frequencies (FO4 and MF4), VDL Mode 2 capacity limitations are not expected before the year 2030; TRTD requirements are fulfilled up to the year 2025 (FO4) and year 2030 (MF4) and are almost fulfilled from 2030 (FO4) and 2035 (MF4) onwards. The proposed Frequency Option 5 (=MF4) with load balancing shows a further advantage over option FO4, such that 4 VDL Mode 2 frequency options could be sufficient up to the year Therefore it can be concluded, that by applying the multi-frequency options FO4 or MF4, reaching VDL Mode 2 capacity limitations can be avoided at least up to the year 2025/2030. It is recommended to investigate further in these promising results obtained when applying Multi- Frequency option MF4. 68 of 151

72 By applying the capacity limitation criteria defined in sub-chapter 5.1 above, we get the following results: Table 47 - Capacity Limitation values, SF, Multi-Frequencies, median traffic growth with AOC migration, high traffic area Conclusions for Lille ScC scenario: SF: "PASS" only for the year 2015 (but refer also to the TRTD values below), "FAIL" for all years at and beyond year FO2: definitely "PASS" only for the year 2015 (TRTD requirements are also fulfilled), but "BORDERLINE" for the year 2020 and "FAIL" for all years at and beyond the year FO3: definitely "PASS" only for the year 2015 (TRTD requirements are also fulfilled), "BORDERLINE" for the years 2020 to 2030 and "FAIL" for all years at and beyond the year FO4: definitely "PASS" for the years 2015 up to 2025 (TRTD requirements are also fulfilled), "PASS" for the years 2030 up to 2040 (TRTD requirements are also almost fulfilled).. MF4: definitely "PASS" for the years 2015 up to year 2030 (TRTD requirements are also fulfilled), and "PASS" for the years 2035 and 2040 (TRTD requirements are also almost fulfilled) ATS application performance For these scenarios the ATS/CPDLC (pass/fail criteria) shows the following results for the Technical Round Trip Delay (TRTD): for the following performance requirements: 95 th percentile target value (max) = 16 seconds 99 th percentile target value (max) = 20 seconds Table 48 - TRTD values, SF, Multi-Frequencies, median traffic growth with AOC migration, high traffic area 69 of 151

73 Conclusions for Lille ScC with AOC migration scenario: The Single-Frequency (SF) option "FAIL"s for all years 2015 and beyond. All Mulit-Frequency Options ( FO2, FO3, FO4 and MF4) "PASS" for the year 2015, but FO2 and FO3 "FAIL" for all years at and beyond year FO4: "PASS" for the years 2015 up to 2025; almost 29 "PASS" for the years 2030 to MF4: "PASS" for the years 2015 up to 2030; almost 30 "PASS" for the years 2035 and Combined VDL Mode 2 capacity and ATS application performance results The combined VDL Mode 2 capacity limitations and performance results (see sub-chapter 5.1 above for details) for the investigated scenario are summarized below. Table 49 Overall results, SF, Multi-Frequencies, median traffic growth with AOC migration, high traffic area Conclusions for Lille ScC AOC migration scenario: SF: "FAIL"s already from the year 2015 and all years beyond. FO2, FO3: "PASS" for the year 2015 only; "FAIL" from the year 2020 onwards. FO4: "PASS" for the years 2015 up to 2025; almost "PASS" for the years 2030 and 2035; "FAIL" from the year 2035 onwards. MF4: "PASS" for the year 2015 up to 2030; almost "PASS" for the years 2035 and The scenario shows advantages with regard to the FO4 frequency option compared to the Lille ScC scenario without AOC migration: FO4 can fulfil the requirements up to the year Note: for this scenario, more than 4 VDL Mode 2 frequencies will be required from the year 2035 onwards. 29 The 99 th percentile with values of 98.3%, 96.6% and 96.0% is close to the target value of 99%. 30 The 99 th percentile with values of 98.9% and 98.8% is close to the target value of 99%. 70 of 151

74 5.3.2 Medium traffic area Optimistic air traffic growth (ScA) VDL Mode 2 capacity limitations Figure 39 - Capacity Limitations, SF, Multi-Frequencies, optimistic traffic growth, high traffic area In this scenario the user data throughput results for the Multi-Frequency Options FO2, FO3, FO4 and MF4 (explained in detail in sub-chapter 0) are considered and compared to the offered load and the Single-Frequency (SF) option. By applying any of the Frequency Options (SF, FO2, FO3, FO4 and MF4), reaching VDL Mode 2 capacity limitations can be avoided today and in the near future. As can be concluded from this graph (Figure 3921 above) and the capacity limitation value table below, although one additional frequency (Frequency options FO2) shows some advantage over the Single-Frequency (SF) scenario, this additional frequency cannot compensate for the significant increase of data traffic estimated for the year 2020 and beyond. Although two additional frequencies, i.e. a total of 3 available VDL Mode 2 frequencies (FO3) show as can be expected further advantages for this scenario, also FO3 seems to be insufficient at least from the year 2025 and beyond. However when applying a total of 4 VDL Mode 2 frequencies (FO4 and MF4), VDL Mode 2 capacity limitations are not expected before the year 2035; TRTD requirements are met up to the year 2030 (FO4) and 2040 (MF4). The proposed Frequency Option 5 (=MF4) with load balancing shows a further advantage over option FO4, such that 4 VDL Mode 2 frequency options could be sufficient up to the year 2040, and it should be noted that TRTD requirements are fully met up to the year Therefore it can be concluded, that by applying the options FO4 or MF4 option, reaching VDL Mode 2 capacity limitations can be avoided at least up to the year It is recommended to investigate further in these promising results obtained when applying Multi- Frequency option MF4. 71 of 151

75 By applying the capacity limitation criteria defined in sub-chapter 5.1 above, we get the following results: Table 50 - Capacity Limitation values, SF, Multi-Frequencies, optimistic traffic growth, medium traffic area Conclusions for Rome ScA scenario: SF: "PASS" only for the year 2015, "FAIL" for all years at and beyond year FO2: definitely "PASS" only for the year 2015 (the TRTD values are also fulfilled), "PASS" for the year 2020 (but the TRTD values below are not fulfilled), "BORDERLINE" for the years 2025 up to 2035 and "FAIL" for the year FO3: definitely "PASS" only for the year 2015 (the TRTD values are also fulfilled), "PASS" for the years 2020 and 2025 (but the TRTD values below are not fulfilled), "BORDERLINE" for the years 2030 onwards. FO4: definitely "PASS" for the years 2015 up to 2030 (the TRTD values below are also fulfilled), and "BORDERLINE" for year MF4: definitely "PASS" for the years 2015 to 2035 (the TRTD values below are also fulfilled), "PASS" for the year 2040 (the TRTD values below are also fulfilled). Note: Only Frequency Option 5 (=MF4) fulfils all requirements up to and including the year ATS application performance For these scenarios the ATS/CPDLC (pass/fail criteria) shows the following results for the Technical Round Trip Delay (TRTD): for the following performance requirements: 95 th percentile target value (max) = 16 seconds 99 th percentile target value (max) = 20 seconds Table 51 TRTD values, SF, Multi-Frequencies, optimistic traffic growth, medium traffic area 72 of 151

76 Conclusions for Rome ScA scenario: All Frequency Options (SF, FO2, FO3, FO4 and MF4) "PASS" with regard to the more stringent TRTD requirements for the year 2015; but SF, FO2 and FO3 "FAIL" from the year 2020 onwards. FO4: "PASS" for the years 2015 up to 2030, and almost 31 "PASS" for the years 2035 and MF4: "PASS" for all years 2015 up to Combined VDL Mode 2 capacity and ATS application performance results The combined VDL Mode 2 capacity limitations and performance results (see sub-chapter 5.1 above for details) for the investigated scenario are summarized below. Table 52 Overall results, SF, Multi-Frequencies, optimistic traffic growth, medium traffic area Conclusions for Rome ScA scenario: SF, FO2: "PASS" for the year 2015 only; "FAIL" from the year 2020 onwards. FO3: "PASS" for the year 2015 only; almost "PASS" for the year 2020; "FAIL" from the year 2025 onwards. FO4: "PASS" for the years 2015 up to 2030; almost "PASS" for the year 2035; "FAIL" for the year MF4: "PASS" for all years from 2015 up to For this scenario, 4 VDL Mode 2 frequencies will be required from the year 2020 onwards. Frequency option FO4 is expected to be sufficient up to the year For this scenario, more than 4 VDL Mode 2 frequencies will not be required until the year 2040 if Frequency Option MF4 (or a frequency management strategy with similar performance) is used. 31 The 95 th percentile is fulfilled, but the 99 th percentile is not fulfilled. 73 of 151

77 Optimistic air traffic growth (ScA) alternative AOC COM VDL Mode 2 capacity limitations Figure 40 - Capacity Limitations, SF, Multi-Frequencies, optimistic traffic growth with AOC migration, medium traffic area In this scenario the user data throughput results for the Multi-Frequency Options FO2, FO3, FO4 and MF4 (explained in detail in sub-chapter 0) are considered and compared to the offered load and the Single-Frequency (SF) option. By applying any of the Frequency Options (SF, FO2, FO3, FO4 and MF4), reaching VDL Mode 2 capacity limitations can be avoided today and in the near future. As can be concluded from this graph (Figure 39 above) and the capacity limitation value table below, although one additional frequency (Frequency options FO2) shows some advantage over the Single- Frequency (SF) scenario, this additional frequency cannot compensate for the significant increase of data traffic estimated for the year 2020 and beyond. Although two additional frequencies, i.e. a total of 3 available VDL Mode 2 frequencies (FO3) show as can be expected further advantages for this scenario, also FO3 seems to be insufficient at least from the year 2025 and beyond. However when applying a total of 4 VDL Mode 2 frequencies (FO4 and MF4), VDL Mode 2 capacity limitations are not expected before the year 2035; TRTD requirements are met up to the year 2035 (FO4) and 2040 (MF4). The proposed Frequency Option 5 (=MF4) with load balancing shows a further advantage over option FO4, such that 4 VDL Mode 2 frequency options could be sufficient up to the year 2040, and it should be noted that TRTD requirements are fully met up to the year Therefore it can be concluded, that by applying the options FO4 or MF4 option, reaching VDL Mode 2 capacity limitations can be avoided at least up to the year It is recommended to investigate further in these promising results obtained when applying Multi- Frequency option MF4. 74 of 151

78 By applying the capacity limitation criteria defined in sub-chapter 5.1 above, we get the following results: Table 53 - Capacity Limitation values, SF, Multi-Frequencies, optimistic traffic growth with AOC migration, medium traffic area Conclusions for Rome ScA with AOC migration scenario: SF: "PASS" only for the year 2015, "FAIL" for all years at and beyond year FO2: definitely "PASS" only for the year 2015 (the TRTD values are also fulfilled), "PASS" for the year 2020 (but the TRTD values below are not fulfilled), "BORDERLINE" for the years 2025 up to FO3: definitely "PASS" only for the year 2015 (the TRTD values are also fulfilled), "PASS" for the years 2020 and 2025 (but the TRTD values below are not fulfilled), "BORDERLINE" for the years 2030 onwards. FO4: definitely "PASS" for the years 2015 up to 2035 (the TRTD values below are also fulfilled), "PASS" for the year 2040 (the TRTD values are almost fulfilled). MF4: definitely"pass" for all years 2015 up to 2040 (the TRTD values below are also fulfilled). Note: Only Frequency Option 5 (=MF4) fulfils all requirements up to and including the year ATS application performance For these scenarios the ATS/CPDLC (pass/fail criteria) shows the following results for the Technical Round Trip Delay (TRTD): for the following performance requirements: 95 th percentile target value (max) = 16 seconds 99 th percentile target value (max) = 20 seconds Table 54 - Capacity Limitation values, SF, Multi-Frequencies, optimistic traffic growth with AOC migration, medium traffic area 75 of 151

79 Conclusions for Rome ScA with AOC migration scenario: All Frequency Options (SF, FO2, FO3, FO4 and MF4) "PASS" with regard to the more stringent TRTD requirements for the year 2015; but SF and FO2 "FAIL" from the year 2020 onwards. FO3: "PASS" for the year 2015, almost 32 "PASS" for the years 2020 up to 2030, but "FAIL"s from the year 2035 onwards.. FO4: "PASS" for the years 2015 up to 2035, and almost 33 "PASS" for the year MF4: "PASS" for all years 2015 up to Combined VDL Mode 2 capacity and ATS application performance results The combined VDL Mode 2 capacity limitations and performance results (see sub-chapter 5.1 above for details) for the investigated scenario are summarized below. Table 55 Overall results, SF, Multi-Frequencies, optimistic traffic growth with AOC migration, medium traffic area Conclusions for Rome ScA AOC migration scenario: SF, FO2: "PASS" for the year 2015 only; "FAIL" from the year 2020 onwards. FO3: "PASS" for the year 2015 only; almost "PASS" from the year 2020 up to 2030; "FAIL" from the year 2035 onwards. FO4: "PASS" for the years 2015 up to 2035; almost "PASS" for the year MF4: "PASS" for all years from 2015 up to For this scenario, 4 VDL Mode 2 frequencies will be required from the year 2020 onwards. Frequency option FO4 is expected to be sufficient up to the year 2035; this is an advantage compared to the Rome ScA scenario (without AOC migration) due to the reduced traffic load caused by the AOC migration. For this scenario, more than 4 VDL Mode 2 frequencies will not be required until the year 2040 if Frequency Option MF4 (or a frequency management strategy with similar performance) is used. 32 The 95 th percentile is fulfilled, the 99 th percentile is not fulfilled, but the values 98.3%, 97.4% and 96.7% are close to the target value of 99%. 33 The 95 th percentile is fulfilled, the 99 th percentile is not fulfilled, but the value 98.2% is close to the target value of 99%. 76 of 151

80 Median air traffic growth (ScC) VDL Mode 2 capacity limitations Figure 41 - Capacity Limitations, SF, Multi-Frequencies, median traffic growth, medium traffic area In this scenario the user data throughput results for the Multi-Frequency Options FO2, FO3, FO4 and MF4 (explained in detail in sub-chapter 0) are considered and compared to the offered load and the Single-Frequency (SF) option. By applying any of the Frequency Options (SF, FO2, FO3, FO4 and MF4), reaching VDL Mode 2 capacity limitations can be avoided today and in the near future. As can be concluded from this graph (Figure 39 above) and the capacity limitation value table below, although one additional frequency (Frequency options FO2) shows some advantage over the Single- Frequency (SF) scenario, this additional frequency cannot compensate for the significant increase of data traffic estimated for the year 2020 and beyond. Although two additional frequencies, i.e. a total of 3 available VDL Mode 2 frequencies (FO3) show as can be expected further advantages for this scenario, but FO3 seems to be insufficient - at least with regard to the TRTD requirements (see below) from the year 2020 and beyond. However when applying a total of 4 VDL Mode 2 frequencies (FO4 and MF4), VDL Mode 2 capacity limitations are not expected before the year 2035; TRTD requirements are met up to the year 2030 (FO4) and 2040 (MF4). The proposed Frequency Option 5 (=MF4) with load balancing shows a further advantage over option FO4, such that 4 VDL Mode 2 frequency options could be sufficient up to the year 2040, and it should be noted that TRTD requirements are fully met up to the year Therefore it can be concluded, that by applying the options FO4 or MF4 option, reaching VDL Mode 2 capacity limitations can be avoided at least up to the year It is recommended to investigate further in these promising results obtained when applying Multi- Frequency option MF4. 77 of 151

81 By applying the capacity limitation criteria defined in sub-chapter 5.1 above, we get the following results: Table 56 - Capacity Limitation values, SF, Multi-Frequencies, median traffic growth, medium traffic area Conclusions for Rome ScC scenario: SF: "PASS" only for the year 2015, "FAIL" for all years at and beyond year FO2: definitely "PASS" only for the year 2015 (the TRTD values are also fulfilled), "PASS" for the year 2020 (but the TRTD values below are not fulfilled), "BORDERLINE" for the years 2025 up to FO3: definitely "PASS" only for the year 2015 (the TRTD values are also fulfilled), "PASS" for the years 2020 up to 2030 (but the TRTD values below are not fulfilled), "BORDERLINE" for the years 2030 onwards. FO4: definitely "PASS" for the years 2015 up to 2030 (the TRTD values below are also fulfilled), "PASS" for the years 2035 and 2040 (the TRTD values are almost fulfilled). MF4: definitely"pass" for all years 2015 up to 2040 (the TRTD values below are also fulfilled). Note: Only Frequency Option 5 (=MF4) fulfils all requirements up to and including the year ATS application performance For these scenarios the ATS/CPDLC (pass/fail criteria) shows the following results for the Technical Round Trip Delay (TRTD): for the following performance requirements: 95 th percentile target value (max) = 16 seconds 99 th percentile target value (max) = 20 seconds Table 57 - TRTD values, SF, Multi-Frequencies, median traffic growth, medium traffic area 78 of 151

82 Conclusions for Rome ScC scenario: All Frequency Options (SF, FO2, FO3, FO4 and MF4) "PASS" with regard to the more stringent TRTD requirements for the year 2015; but SF and FO2 "FAIL" from the year 2020 onwards. FO3: "PASS" for the year 2015, almost 34 "PASS" for the years 2020 up to 2030, but "FAIL"s from the year 2035 onwards.. FO4: "PASS" for the years 2015 up to 2030, and almost 35 "PASS" for the years 2035 and MF4: "PASS" for all years 2015 up to Combined VDL Mode 2 capacity and ATS application performance results The combined VDL Mode 2 capacity limitations and performance results (see sub-chapter 5.1 above for details) for the investigated scenario are summarized below. Table 58 Overall results, SF, Multi-Frequencies, median traffic growth, medium traffic area Conclusions for Rome ScC scenario: SF, FO2: "PASS" for the year 2015 only; "FAIL" from the year 2020 onwards. FO3: "PASS" for the year 2015 only; almost "PASS" from the year 2020 up to 2030; "FAIL" from the year 2035 onwards. FO4: "PASS" for the years 2015 up to 2030; almost "PASS" for the years 2035 and MF4: "PASS" for all years from 2015 up to For this scenario, 4 VDL Mode 2 frequencies will be required from the year 2020 onwards. Frequency option FO4 is expected to be sufficient up to the year For this scenario, more than 4 VDL Mode 2 frequencies will not be required until the year 2040 if Frequency Option MF4 (or a frequency management strategy with similar performance) is used. 34 The 95 th percentile is fulfilled, the 99 th percentile is not fulfilled, but the values 98.4%, 97.2% and 97.2% are close to the target value of 99%. 35 The 95 th percentile is fulfilled, the 99 th percentile is not fulfilled, but the values of 98.1% are close to the target value of 99%. 79 of 151

83 Median air traffic growth (ScC) alternative AOC COM VDL Mode 2 capacity limitations Figure 42 - Capacity Limitations, SF, Multi-Frequencies, median traffic growth with AOC migration, medium traffic area In this scenario the user data throughput results for the Multi-Frequency Options FO2, FO3, FO4 and MF4 (explained in detail in sub-chapter 0) are considered and compared to the offered load and the Single-Frequency (SF) option. By applying any of the Frequency Options (SF, FO2, FO3, FO4 and MF4), reaching VDL Mode 2 capacity limitations can be avoided today and in the near future. As can be concluded from this graph (Figure 42 above) and the capacity limitation value table below, although one additional frequency (Frequency options FO2) shows some advantage over the Single- Frequency (SF) scenario, this additional frequency cannot compensate for the significant increase of data traffic estimated for the year 2020 and beyond. Although two additional frequencies, i.e. a total of 3 available VDL Mode 2 frequencies (FO3) show as can be expected further advantages for this scenario, but FO3 seems to be insufficient - at least with regard to the TRTD requirements (see below) from the year 2020 and beyond. However when applying a total of 4 VDL Mode 2 frequencies (FO4 and MF4), VDL Mode 2 capacity limitations are not expected before the year 2035; TRTD requirements are met up to the year 2030 (FO4) and 2040 (MF4). The proposed Frequency Option 5 (=MF4) with load balancing shows a further advantage over option FO4, such that 4 VDL Mode 2 frequency options could be sufficient up to the year 2040, and it should be noted that TRTD requirements are fully met up to the year Therefore it can be concluded, that by applying the options FO4 or MF4 option, reaching VDL Mode 2 capacity limitations can be avoided at least up to the year It is recommended to investigate further in these promising results obtained when applying Multi- Frequency option MF4. 80 of 151

84 By applying the capacity limitation criteria defined in sub-chapter 5.1 above, we get the following results: Table 59 - Capacity Limitation values, SF, Multi-Frequencies, median traffic growth with AOC migration, medium traffic area Conclusions for Rome ScC AOC migration scenario: SF: "PASS" only for the year 2015, "FAIL" for all years at and beyond year FO2: definitely "PASS" only for the year 2015 (the TRTD values are also fulfilled), "PASS" for the year 2020 (but the TRTD values below are not fulfilled), "BORDERLINE" for the years 2025 up to FO3: definitely "PASS" only for the year 2015 (the TRTD values are also fulfilled), "PASS" for the years 2020 up to 2030 (but the TRTD values below are not fulfilled), "BORDERLINE" for the years 2035 onwards. FO4: definitely"pass" for all years 2015 up to 2040 (the TRTD values below are also fulfilled). MF4: definitely"pass" for all years 2015 up to 2040 (the TRTD values below are also fulfilled). Note:Both Frequency Option 4 and 5 (=FO4 and MF4) fulfil all requirements up to and including the year ATS application performance For these scenarios the ATS/CPDLC (pass/fail criteria) shows the following results for the Technical Round Trip Delay (TRTD): for the following performance requirements: 95 th percentile target value (max) = 16 seconds 99 th percentile target value (max) = 20 seconds Table 60 - TRTD values, SF, Multi-Frequencies, median traffic growth with AOC migration, medium traffic area 81 of 151

85 Conclusions for Rome ScC with AOC migration scenario: All Frequency Options (SF, FO2, FO3, FO4 and MF4) "PASS" with regard to the more stringent TRTD requirements for the year 2015; but SF and FO2 "FAIL" from the year 2020 onwards. FO3: "PASS" for the year 2015 and almost 36 "PASS" for the years 2020 up to FO4: "PASS" for all years 2015 up to MF4: "PASS" for all years 2015 up to Combined VDL Mode 2 capacity and ATS application performance results The combined VDL Mode 2 capacity limitations and performance results (see sub-chapter 5.1 above for details) for the investigated scenario are summarized below. Table 61 Overall results, SF, Multi-Frequencies, median traffic growth with AOC migration, medium traffic area Conclusions for Rome ScC AOC migration scenario: SF, FO2: "PASS" for the year 2015 only; "FAIL" from the year 2020 onwards. FO3: "PASS" for the year 2015 only; almost "PASS" from the year 2020 up to 2030; "FAIL" from the year 2035 onwards. FO4: "PASS" for the years 2015 up to 2030; almost "PASS" for the years 2035 and MF4: "PASS" for all years from 2015 up to For this scenario, 4 VDL Mode 2 frequencies will be required from the year 2020 onwards. Both Frequency Options FO4 and MF4 are expected to be sufficient up to the year For this scenario, more than 4 VDL Mode 2 frequencies will not be required until the year 2040 if Frequency Option FO4 or MF4 (or a frequency management strategy with similar performance) is used. 36 The 95 th percentile is fulfilled, the 99 th percentile is not fulfilled, but the values 98.4%, 97.5%, 98.0% and 95.2% are close to the target value of 99%. 82 of 151

86 High traffic area The following contains a graphical overview showing the main capacity performance of the various VDL Mode 2 ground stations forming the VDL Mode 2 network. The figures on the next pages show for each year 2015, 2020, 2025, 2030, 2035 and 2040 and for each frequency option: SF: Single Frequency FO2: Frequency Option 2 (2 frequencies) FO3: Frequency Option 3 (3 frequencies) FO4: Frequency Option 4 (4 frequencies) MF4: Frequency Option 5 (4 frequencies with load balancing) the VDL Mode 2 performance (capacity limitation) for each VDL Mode 2 ground station. The capacity limitation results of the detailed VDL Mode 2 simulations are expressed as relative value of User Data Offered Load to User Data Throughput. A coloured categorization has been applied to the results in order to support a quick and comprehensive understanding of the output: In the maps below, each VDL Mode 2 ground station is marked with a circle, which indicates the performance of the specific station: >= 95%: very good (dark green) PASS >= 90% up to 95%: good (light green) still PASS >= 85% up to 90%: becoming critical (yellow) BORDERLINE >= 80% up to 85%: critical (orange) definitely BORDERLINE < 80%: (red) - definitely FAIL. 83 of 151

87 Figure 43: VDL Mode 2 GS network performance Optimistic Traffic - Single- (SF) and Multi-Frequency scenarios: FO2, FO3, FO4, MF4 Year 2015

88 Figure 44: VDL Mode 2 GS network performance Optimistic Traffic - Single- (SF) and Multi-Frequency scenarios: FO2, FO3, FO4, MF4 Year of 151

89 86 of 151

90 Figure 45: VDL Mode 2 GS network performance Optimistic Traffic - Single- (SF) and Multi-Frequency scenarios: FO2, FO3, FO4, MF4 Year of 151

91 Figure 46: VDL Mode 2 GS network performance Optimistic Traffic - Single- (SF) and Multi-Frequency scenarios: FO2, FO3, FO4, MF4 Year of 151

92 Figure 47: VDL Mode 2 GS network performance Optimistic Traffic - Single- (SF) and Multi-Frequency scenarios: FO2, FO3, FO4, MF4 Year of 151

93 Figure 48: VDL Mode 2 GS network performance Optimistic Traffic - Single- (SF) and Multi-Frequency scenarios: FO2, FO3, FO4, MF4 Year of 151

94 Figure 49: VDL Mode 2 GS network performance Median Traffic - Single- (SF) and Multi-Frequency scenarios: FO2, FO3, FO4, MF4 Year of 151

95 Figure 50: VDL Mode 2 GS network performance Median Traffic - Single- (SF) and Multi-Frequency scenarios: FO2, FO3, FO4, MF4 Year of 151

96 Figure 51: VDL Mode 2 GS network performance Median Traffic - Single- (SF) and Multi-Frequency scenarios: FO2, FO3, FO4, MF4 Year of 151

97 Figure 52: VDL Mode 2 GS network performance Median Traffic - Single- (SF) and Multi-Frequency scenarios: FO2, FO3, FO4, MF4 Year of 151

98 Figure 53: VDL Mode 2 GS network performance Median Traffic - Single- (SF) and Multi-Frequency scenarios: FO2, FO3, FO4, MF4 Year of 151

99 Medium traffic area The following contains a graphical overview showing the main capacity performance of the various VDL Mode 2 ground stations forming the VDL Mode 2 network. The figures on the next pages show for each year 2015, 2020, 2025, 2030, 2035 and 2040 and for each frequency option: SF: Single Frequency FO2: Frequency Option 2 (2 frequencies) FO3: Frequency Option 3 (3 frequencies) FO4: Frequency Option 4 (4 frequencies) MF4: Frequency Option 5 (4 frequencies with load balancing) the VDL Mode 2 performance (capacity limitation) for each VDL Mode 2 ground station. The capacity limitation results of the detailed VDL Mode 2 simulations are expressed as relative value of User Data Offered Load to User Data Throughput. A coloured categorization has been applied to the results in order to support a quick and comprehensive understanding of the output: In the maps below, each VDL Mode 2 ground station is marked with a circle, which indicates the performance of the specific station: >= 95%: very good (dark green) PASS >= 90% up to 95%: good (light green) still PASS >= 85% up to 90%: becoming critical (yellow) BORDERLINE >= 80% up to 85%: critical (orange) definitely BORDERLINE

100 Figure 54 - VDL Mode 2 GS network performance Optimistic Traffic - Single- (SF) and Multi-Frequency scenarios: FO2, FO3, FO4, MF4 Year 2015

101 Figure 55: VDL Mode 2 GS network performance Optimistic Traffic - Single- (SF) and Multi-Frequency scenarios: FO2, FO3, FO4, MF4 Year of 151

102 Figure 56: VDL Mode 2 GS network performance Optimistic Traffic - Single- (SF) and Multi-Frequency scenarios: FO2, FO3, FO4, MF4 Year of 151

103 Figure 57: VDL Mode 2 GS network performance Optimistic Traffic - Single- (SF) and Multi-Frequency scenarios: FO2, FO3, FO4, MF4 Year of 151

104 Figure 58: VDL Mode 2 GS network performance Optimistic Traffic - Single- (SF) and Multi-Frequency scenarios: FO2, FO3, FO4, MF4 Year of 151

105 102 of 151

106 Figure 59: VDL Mode 2 GS network performance Optimistic Traffic - Single- (SF) and Multi-Frequency scenarios: FO2, FO3, FO4, MF4 Year of 151

107 Figure 60: VDL Mode 2 GS network performance Median Traffic - Single- (SF) and Multi-Frequency scenarios: FO2, FO3, FO4, MF4 Year of 151

108 Figure 61: VDL Mode 2 GS network performance Median Traffic - Single- (SF) and Multi-Frequency scenarios: FO2, FO3, FO4, MF4 Year of 151

109 Figure 62: VDL Mode 2 GS network performance Median Traffic - Single- (SF) and Multi-Frequency scenarios: FO2, FO3, FO4, MF4 Year of 151

110 Figure 63: VDL Mode 2 GS network performance Median Traffic - Single- (SF) and Multi-Frequency scenarios: FO2, FO3, FO4, MF4 Year of 151

111 Figure 64: VDL Mode 2 GS network performance Median Traffic - Single- (SF) and Multi-Frequency scenarios: FO2, FO3, FO4, MF4 Year of 151

112 6 Conclusions This very detailed study have considered the complete European environment and traffic, for then focus the results on what the consortium believed are a good representation of an high density area and a medium density area in terms of traffic. All VDL Mode 2 ground stations, as indicated by CSPs/ANSP, have been considered in the ECAC area and, as terms of reference of the study, no geographical redistributions of those ground stations has been considered. Of course changing the distribution of VDL Mode 2 ground stations all around Europe may change the outcome of this study. The results of the study are based on assumptions, detailed within the document, that the consortium believed are representing the most realistic scenario until The VDL Mode 2 protocol considered is the one currently used by many European ANSPs/CSPs and indicated in the European Commission Regulation (EC) No 29/2009 about requirements on data link services for the Single European Sky. The Multi-Frequency options, in terms of frequencies usage, are the one that the consortium believed are the most promising ones, in terms of better utilization of the four VDL Mode 2 channels. As general remark, the study have proved that: VDL Mode 2 will reach a capacity limit at a certain point of time. Therefore it is urgent to work on the development of the next generation Datacom system. Multi Frequency deployment is a MUST today, especially in area at high density area. Anyway it is important to start on having a single frequency environment working perfectly, on which a Multi Frequency environment can be built on top of. A 4 frequencies implementation is a minimum to support VDL Mode 2 deployment until 2025 in high density area, if the datalink will be used as assumed on the study. Other studies, outside of this VDL Mode 2 capacity scope, may consider the optimization of VDL Mode 2 protocol and some configuration changes on ground stations. Those activities may extend the viability of the VDL Mode 2 link beyond 2025 in high density area. The main conclusions for the single and multi-frequency environment are as follows: 6.1 High Traffic Area (Lille) This area reaches its VDL Mode 2 capacity limitations already today or in the near future. This is supported both by: the comparison of the "offered load" (i.e. what a user wants to send (per time unit)) and the "user data throughput" (i.e. what is finally received successfully at VDL Mode 2 application level at the destination) and the operational performance concerning ATS/CPDPC messages with regard to the Technical Round Trip Delay (TRTD) for which target values (max) for the 95 th percentile (16 seconds) and for the 99 th percentile (20 seconds) are defined in the reference document "Link DLS CRO Performance Monitoring Requirements", Eurocontrol / Network Manager Directorate, David Isaac, Ed. 1.3, 19 May In particular, we can see that: for the optimistic traffic growth we have recorded:

113 Figure 65 - Capacity Limitations and TRTD values, SF, Multi-Frequencies, optimistic traffic growth, high traffic area Figure 66 - Overall results, Single-Frequency (SF), optimistic traffic growth, high traffic area for the optimistic traffic growth, with AOC migration, we have recorded: Figure 67 - Capacity Limitations and TRTD values, SF, Multi-Frequencies, optimistic traffic growth with AOC migration, high traffic area Figure 68 Overall results, SF, Multi-Frequencies, optimistic traffic growth with AOC migration, high traffic area for the median traffic growth we have recorded: 110 of 151

114 Figure 69 - Capacity Limitations and TRTD values, SF, Multi-Frequencies, medium traffic growth, high traffic area Figure 70 Overall results, SF, Multi-Frequencies, median traffic growth, high traffic area 111 of 151

115 for the medium traffic growth, with AOC migration, we have recorded: Figure 71 - Capacity Limitations and TRTD values, SF, Multi-Frequencies, medium traffic growth with AOC migration, high traffic area Figure 72 Overall results, SF, Multi-Frequencies, median traffic growth with AOC migration, high traffic area The detailed VDL Mode 2 simulation results show, that from 2020 onwards (both for the optimistic traffic scenario as well as even for the median traffic scenario) there is a significant gap between the "offered load" and the "user data throughput", which means that data is significantly delayed and/or lost and the operational ATC/CPDLC performance requirements (TRTD) are not met. The following major airports are located within the high traffic area of interest (Lille): Amsterdam Schiphol (AMS) Brussels International (BRU) Düsseldorf (DUS) London City (LCY) London Gatwick (LGW) London Heathrow (LHR) London Luton (LTN) London Stansted (STN) Paris Charles de Gaulle (CDG) Paris Orly (ORY) When analysing the VDL Mode 2 simulation characteristics and results in detail, the following performance results can be observed for the different VDL Mode 2 ground stations (ARINC and SITA) for the baseline year 2014/15: 112 of 151

116 Figure 73 - High Traffic Area - ARINC Stations Baseline Year 2014/15 ARINC operates one VDL Mode 2 ground station per major airport. The total number of ARINC stations within the area of interest is 8. There is no ARINC station located in DUS and LCY. Figure 74 - High Traffic Area - SITA Stations Baseline Year 2014/15 SITA operates one or two VDL Mode 2 ground stations on each of the major airports. The total number of SITA stations within the area of interest is 13. There are no ARINC stations located in DUS and LCY. The traffic load is highest in AMS and CDG and lowest in LTN (ARINC) and LCY (SITA). The ATS traffic exceeds the AOC traffic significantly in CDG only. The ATS and AOC traffic are approximately the same in AMS (high),dus (medium), LCY (low), PAR7 (SITA; low), PARU (SITA; low)) and ORY (high). The ATS traffic is significantly lower than the AOC traffic in LGW, LHR. 113 of 151

117 The loss rates (see Appendix for details) are significantly high for AMS (ARINC) and BRU (ARINC). This is probably caused by the fact that adjacent VDL Mode 2 ground stations are farer away for ARINC than for SITA, as ARINC does not operate a VDL Mode 2 ground station in DUS. Please note, that the assumption for ATS data traffic is that every aircraft is transmitting data messages on a regular basis. Therefore, the data traffic volume of ATS becomes much higher than today. AOC data traffic was derived from real data application load based on input data from SITA. This clearly shows that ATS data application load will affect the data volume significantly once air space users are utilizing data communication means more heavily. Please note further that Figure 73 and Figure 74 (above) show only ATS and AOC results for the baseline scenario year 2014/2015. Please refer to Section "Assumptions on AOC and ATS Traffic Load" for a clear picture on how ATS and AOC data traffic has been taken into account based on assumptions for ATN Baseline 1 (ATN/B1: year 2015 and year 2020), ATN Baseline 2 (ATN/B2; year 2025 and year 2030), and ATN Baseline 3 (ATN/B3; year 2035 and year 2040) and AOC evolution (year 2015 up to year 2040). The impact of these ATS and AOC data traffic assumptions are summarized for single-and multifrequency scenarios, high and medium traffic area (year 2015 up to year 2040) below. The main conclusions for the single and multi-frequency environment for the high density area are as follows: A single VDL Mode 2 frequency (SF) seems not to be sufficient for the high density area for all investigated scenarios (optimistic or median traffic, with or without AOC migration) already for today (year 2015). The Frequency Options with two VDL Mode 2 frequencies (FO2) and three frequencies (FO3) are not expected to be sufficient from the year 2020 onwards. A total of four VDL Mode 2 frequencies will be required from the year 2020 onwards. Frequency Option FO4 (4 frequencies) is expected to meet the requirements at least until the year 2020 but certainly not from the year 2030 onwards. Only Frequency Option MF4 (or a frequency management strategy with similar performance) is expected to provide the required performance until the year For all scenarios (optimistic or median traffic as well as with or without AOC migration), more than 4 VDL Mode 2 frequencies are expected to be required for the High density area (or areas with similar high air traffic density) at least from the year 2035 onwards. The main reason for the conclusion that two or even three VDL Mode 2 frequency channels will not be sufficient already from the year 2020 onwards, is the significant increase in data traffic load expected towards the year Compared to the year 2015 the ATS / Enroute traffic load for ATN_B1 (100% equipped rate) will increase - for the year by a factor of around 2.5. Taking the increase of AOC data traffic (around 20%) and the increase of air traffic (around flights today and around flights expected in 2020) of around 25% into account the overall increase (ATS + AOC traffic) will be around 230 %. This is well confirmed by the detailed VDL Mode 2 simulations carried out in the context of this study, when looking into the graph (Figure 57 Comparison of Offered Load for various scenarios High traffic vs. Medium traffic area, below): The increase of Offered Load for the Lille area from 2015 to 2020 is 236%! From this estimation it can be concluded that two and even three VDL Mode 2 frequency channels will not be sufficient to carry the increase of data amount which is expected to be around 2.5 to 3 times 114 of 151

118 higher for the year 2020 than today, when a single VDL Mode 2 frequency channel is reaching its saturation already today. This is well confirmed by the detailed VDL Mode 2 simulations carried out in the context of this study. 6.2 Medium Traffic Area (Rome) For this area, the single VDL Mode 2 frequency (SF) seems to be sufficient to manage the datalink traffic for the today s scenario (2015), with performances that allow its usage for ATS traffic. However from 2020 onwards, a single frequency will not be sufficient, and so using the 4 VDL Mode 2 frequency channels will be required. This is supported by: the comparison of the "offered load" (i.e. what a user wants to send (per time unit)) and the "user data throughput" (i.e. what is finally received successfully at VDL Mode 2 application level at the destination) and the operational performance concerning ATS/CPDPC messages with regard to the Technical Round Trip Delay (TRTD) for which target values (max) for the 95 th percentile (16 seconds) and for the 99 th percentile (20 seconds) are defined in the reference document "Link DLS CRO Performance Monitoring Requirements", Eurocontrol / Network Manager Directorate, David Isaac, Ed. 1.3, 19 May In particular we can see that: for the optimistic traffic growth we have recorded: Figure 75 - Capacity Limitations and TRTD values, SF, Multi-Frequencies, optimistic traffic growth, medium traffic area Figure 76 Overall results, SF, Multi-Frequencies, optimistic traffic growth, medium traffic area 115 of 151

119 for the optimistic traffic growth, with AOC migration, we have recorded: Figure 77 - Capacity Limitations and TRTD values, SF, Multi-Frequencies, optimistic traffic growth with AOC migration, medium traffic area Figure 78 Overall results, SF, Multi-Frequencies, optimistic traffic growth with AOC migration, medium traffic area for the median traffic growth we have recorded: Figure 79 - Capacity Limitations and TRTD values, SF, Multi-Frequencies, medium traffic growth, medium traffic area Figure 80 Overall results, SF, Multi-Frequencies, median traffic growth, medium traffic area 116 of 151

120 for the medium traffic growth, with AOC migration, we have recorded: Figure 81 - Capacity Limitations and TRTD values, SF, Multi-Frequencies, medium traffic growth with AOC migration, medium traffic area Figure 82 Overall results, SF, Multi-Frequencies, median traffic growth with AOC migration, medium traffic area While there are 10 major airports in the high traffic area, there is only a single major airport and some smaller airports in the medium traffic area: Rome Fiumicino Rome Ciampino Napoli Airport Costa Smeralda (Olbia) Airport However it should be noted that a significant amount of en-route traffic is routed through the medium traffic area. The reason why significantly different conclusions with regard to the VDL Mode 2 capacity limitations are drawn for the high traffic area and the medium traffic area respectively is the different level of data traffic load as depicted in Figure 83 below. 117 of 151

121 Figure 83 Comparison of Offered Load for various scenarios High traffic vs. Medium traffic area The following can be concluded from this graph (Figure 83): The data traffic load for the high traffic area (Lille) is about 3.5 times higher than for the medium traffic area (Rome). The expected data load for the year 2020 is around 2.5 times higher than today for the Lille area, and around 3 times higher for the Rome area. The expected migration to alternate communication technologies for exchanging AOC data traffic instead over VDL Mode 2 - from the year 2025 onwards contributes significantly to a reduction of the data load. As is shown in this graph, even the optimistic traffic scenario with AOC migration (= MIG ScA) causes a lower data traffic load than the median traffic without considering AOC migration (= ScC). When analyzing the VDL Mode 2 simulation characteristics and results in detail, the following performance results can be observed for the different VDL Mode 2 ground stations (ENAV) for the baseline year 2014/15: Figure 84 - Medium Traffic Area - ENAV Stations Baseline Year 2014/15 The following can be concluded from this graph (Figure 84): 118 of 151

122 The number of aircraft is highest in ROMA FCO1 and lowest in ROMA ACC CIAMPINO and ROMA FCO2. The traffic load is highest at ROMA FCO1 and lowest in ROMA ACC CIAMPINO and ROMA FCO2. The ATS traffic exceeds the AOC traffic significantly in ROMA FCO1, in NAPOLI and in OLBIA only. The AOC traffic is (slightly) higher than the ATS traffic in ROMA ACC CIAMPINO and in ROMA FCO2. The main conclusions for the single- and multi-frequency environment for the Rome area are as follows: A single VDL Mode 2 frequency (SF) is sufficient for the Rome area for all scenarios (optimistic or median traffic, with or without AOC migration) for the year 2015 and the near future. The Frequency Options with two VDL Mode 2 frequencies (FO2) and three frequencies (FO3) are not expected to be sufficient from the year 2020 onwards. A total of four VDL Mode 2 frequencies will be required from the year 2020 onwards. Frequency Option FO4 (4 frequencies) is expected to meet the requirements at least until the year Both Frequency Options FO4 and MF4 are expected to fulfil the requirements up to the year 2040 for the scenario with median traffic growth (ScC) and switching to other AOC COM alternatives (AOC migration from the year 2025 onwards). For all scenarios (optimistic or median traffic as well as with or without AOC migration), more than 4 VDL Mode 2 frequencies are not expected to be required for the Rome area until the year 2040 if the Frequency Option MF4 (or a frequency management strategy with similar performance) is used. The main reason for the conclusion that two or even three VDL Mode 2 frequency channels will not be sufficient already from the year 2020 onwards, is the significant increase in data traffic load expected towards the year Compared to the year 2015 the ATS / Enroute traffic load for ATN_B1 (100% equipped rate) will increase - for the year by a factor of around 2.5. Taking the increase of AOC data traffic (around 20%) and the increase of air traffic (around flights today and around flights expected in 2020) of around 25% into account the overall increase (ATS + AOC traffic) will be around 230 %. This is confirmed by the detailed VDL Mode 2 simulations carried out in the context of this study, when looking into the graph (Figure 75, above): The increase of Offered Load from 2015 to 2020 for the Lille area is 236% and for the Rome area it is even higher (around 320%)! From this estimation it can be concluded that two and even three VDL Mode 2 frequency channels will not be sufficient to carry the increase of data amount which is expected to be around 2.5 to 3 times higher for the year 2020 than today, when a single VDL Mode 2 frequency channel is reaching its saturation already today. This is well confirmed by the detailed VDL Mode 2 simulations carried out in the context of this study. 119 of 151

123 7 [1] Link DLS CRO Performance Monitoring Requirements, Eurocontrol / Network Manager Directorate, David Isaac, Ed. 1.3, 19 May 2014 [2] Requirements for monitoring through VDL Mode 2 channels edition, Eurocontrol [3] ICAO EUR FREQUENCY MANAGEMENT MANUAL, ICAO EUROPEAN AND NORTH ATLANTIC OFFICE, Doc 011, Edition 2014 [4] Ad Hoc meeting on EUROCONTROL MF Roadmap, 2 nd December 2013, EUROCONTROL [5] Steven C. Bretmersky, Robert R. Murawski, and Vijay K. Konangi. "Characteristics and Capacity of VDL Mode 2, 3, and 4 Subnetworks", Journal of Aerospace Computing, Information, and Communication, Vol. 2, No. 11 (2005), pp of 151

124 Appendix A A.1 Work Breakdown Structure The project was organised upon a Work Breakdown Structure which covered all required activities while allowing for clear identification of the competences to be provided by each Consortium partner. The Figure below summarises the highest level of the WBS decompositions into WPs and Tasks. Figure 85 - Work Breakdown Structure Each task was led by a single partner, which was overall responsible for the timely conduction of all activities. Each task was participated mainly by a number of partners, depending on the required competences.

125 A short description of each WP objectives follows in the next pages. A.1.1 WP1 Management Work Package 1 (WP1) will deal with the detailed project plan which is delivered through the deliverable D0. Enav leads this Work Package, with the contribution of all consortium partners. swp 1.1 Overall Consortium Coordination This activity is dedicated to ensuring proper coordination at management level among partners. The Task is allocated to the consortium Steering Group, which will be the ultimate responsible to implement the project and is responsible for monitoring all the project activities, their progress, the milestones achieved, and the effort spent in future periods. In case of problems it will be also responsible to define mitigation actions or contingency plans to apply, and to look for arbitration among project parties in case of any issue being escalated at such level. The task will be conducted by organizing at least one plenary Meeting and a Final Closing Meeting. Webex meetings and offline coordination conducted by phone and will be ensured as needed. swp 1.2 Monitoring & Controlling, Risk management This activity will provide day by day control of the proper execution of the project, report, support finance administrations for timely and correct presentation of Eligible Costs, identify and prevent risk and mitigate their potential effect, identify and take advantage of any opportunity, address and help solving issues and the related escalation processes. The task is allocated to the consortium leader. swp 1.3 Project & Demonstration Planning This activity will refine the project and demonstration planning within 30 calendar days after project KOM, as for Call Technical specifications. These will include a description of the simulation capabilities, the plan of simulation and experiments, the description of how the simulation assets will be integrated, an initial concept description with a preliminary list of use cases and their allocations to the demonstration activities. swp 1.4 Quality Assurance & Configuration magament This activity will ensure that the Project complies with quality standard, by providing templates, ensure document archiving, versioning and sharing into a distributed collaborative environment. Whenever applicable, SESAR available templates will be adapted to keep consistency with the current way of working and avoiding "re-inventing the wheel". A.1.2 WP2 Characterization of Applications Work Package 2 (WP2) covers the characterization of all data applications relevant for the analysis. A pragmatic approach to characterize aeronautical data applications is used. The approach is based on the methodology described in section 3.1. In such a way it becomes possible to apply the same approach for all applications/services to be considered for this study. The output of that work package is the detailed characterization of all application/services including performance requirements. This characterization is used as direct input to create application profiles. Such an application profile is a set of applications/services to be used by aircraft. Application profiles is a part of a simulation scenario configuration. The characterization of applications/services include failure conditions. In such a way it becomes possible to assess a break-even performance of VDL Mode 2. The output of that work package is detailed in deliverable D1.1 Detailed specification of the baseline scenario. swp2.1 LINK Within this work package data link services specification with mandatory message set will be evaluated. Services are: DLIC (Data Link Initiation Capability) 122 of 151

126 This service deals with exchange of address information ( ATN-Port ), supported applications (type and version) etc. to allow for establishing a CPDLC transport connection between ground and airborne ATN system. ACM (ATC Communication Management) This service covers Data Link supported automated hand-off. ACL (ATC Clearances) This service includes clearances like Heading Change, Climb/Descend to Fly. AMC (ATC Microphone Check) This service provides info to all A/C within sector to check Stuck Microphone. DFS leads this sub-work Package, with the contributions of all the consortium partners. swp2.2 FANS 1/A Within this work package data link services belonging to the FANS 1/A service set is evaluated: FANS1/A required ATS applications: CM Application CPDLC Application ADS-C Application CPDLC consists of: Clearance Delivery (CRD) Service Information Exchange and Reporting (IER) Service ATC Communications Management (ACM) Service ATC Microphone Check (AMC) Service ADS-C consists of: Position reports Information Exchange and Reporting (IER) Service NATS leads this sub-work Package, with the contributions of all the consortium partners. swp2.3 AOC Within this work package AOC data link services is evaluated. Sources of reference are: COCRv2 SJU AOC Datalink dimensioning Operational knowledge of supporting airlines (e.g. EasyJet, Air France, Lufthansa) and Communications Service Provider (e.g.sita) ENAV leads this sub-work Package, with the contributions of SITA all the consortium partners. swp2.4 ATN Service Set B2 Within this work package data link services belonging to the ATN Service Set B2 is evaluated. Required ATS applications: CM Application CPDLC Application ADS-C Application CM application supports: Data link Initiation Capability (DLIC) Service CPDLC application supports: ATC Communications Management (ACM) Service ATC Microphone Check (AMC) Service Departure Clearance (DCL) Service 123 of 151

127 Clearance Delivery (CRD) Service Information Exchange and Reporting (IER) Service Position Report (PR) Service In Trail Procedure (ITP) Service Flight Interval Management (FIM) Service Oceanic Clearance Delivery (OCL) Service Data Link Taxi (D-TAXI) Service 4D Trajectory Data link (4DTRAD) Service ADS-C application supports: Information Exchange and Reporting (IER) Service Position Reporting (PR) Service 4D Trajectory Data link (4DTRAD) Service Note: main enabler is ADS-C EPP (Extended Projected Profile) report, which contains the sequence of 1 to 128 waypoints or pseudo waypoints of the FMS active Flight Plan with associated constraints or estimates (altitude, time, speed, etc) and current gross mass. The 4DTRAD service uses CPDLC for the provision of 4D clearances and ADS-C for acquiring trajectory data from the aircraft by the 4DTRAD service provider for: enhanced trajectory definition and prediction, trajectory intent and trajectory constraint coordination, and trajectory intent and trajectory constraint conformance monitoring. LFV leads this sub-work Package, with the contributions of all the consortium partners. swp2.5 Future Services beyond ATN B2 Within this work package data link services beyond ATN Service Set B2 is evaluated. Possible evaluations include (but are not limited to): FIS/MET applications Adapted AOC data applications Full 4D application/service ENAIRE leads this sub-work Package, with the contributions of all the consortium partners. A.1.3 WP3 Scenario Definition Work Package 3 (WP3) create a reasonable amount of simulation scenarios that is used as direct input for the simulations. A simulation scenario needs to consist of a mobility model (i.e. air traffic), a topology model (ground station deployment and frequency options), and a data model. The following items characterize a simulation scenario: Air traffic (i.e. includes target year and growth assumptions) including area of interest VDL Mode 2 Ground Station topology (geographical location of VDL Mode 2 ground stations) Frequency deployment options (all options will be simulated separately) Application profile to be used (i.e. applications/services specified in WP2) The output of that work-package is detailed in D1.1 Detailed specification of the baseline scenario. ENAV leads the entire Work Package, with the contributions of all the consortium partners. swp3.1 Air Space Definition swp 3.1 consider different aspects of the defined airspace that may become relevant for the study. It is intended to analyze a single airspace, however, if required the study not be restricted to a single airspace. It is noted, though, that the number of results and reports is kept at a manageable level. At the current state the area of interest is within the peak air traffic area of Europe (such as the extended 124 of 151

128 TMA areas of Paris and/or London). The output of this work-package is the definition of a dedicated air space to be analyzed. The output is represented as a polygon of geodetic edge points (i.e. latitude and longitude positions). swp3.2 Deployment Options swp 3.2 consider the VDL Mode 2 ground station deployment options and the prevision of percentage of capable aircraft per the different capability packages (as specified on WP2). This includes the location of all available VDL Mode 2 ground stations within a given area of interest. Additionally, various options to deploy a multi-frequency strategy is elaborated within this workpackage. That is, 1.) A technical concept to realize a deployment of multiple frequencies within the given area of interest is elaborated in accordance with technical and possibly operational constraints. 2.) An operational concept to assign a frequency to any given aircraft. Possibilities for individual frequency selection algorithms may also be considered. The output of this work package is the position of each VDL Mode 2 ground station to be considered and a set of options to use multiple frequencies for the same ground station deployment. The frequency assignment strategy needs to be elaborated during the course of the study. Another output is the percentage of aircraft equipped with a certain technology. swp3.3 Scenario compilation WP3.3 gathers the outputs of the different sub-work-packages of WP 2 and WP 3 and compiles the set of scenarios to be simulated. This list include all necessary parameter settings required by the simulation. A.1.4 WP4 Simulation and reports Work Package 4 (WP4) cover the simulation aspect of the study. In order to simulate the scenarios defined in WP3, different simulation tools will be used. These tools (described in the previous sections) need adaptations to comply with the study requirements. The output of this work package is reflected in multiple deliverables. Deliverable D1.2 Simulation results template provide the basis for the capacity and performance assessment of VDL Mode 2. Based on this template, results gained by running individual simulation scenarios is reported in separate deliverables (i.e. D2.X Simulation run ). Finally, deliverable D3 Final Report reflect in a summary the key results gained from the complete simulation campaign. This deliverable also conclude the capacity and performance assessment of VDL Mode 2. University of Salzburg leads this Work Package, with the exclusion of swp 4.5, with the contributions of all the consortium partners. swp4.1 Air traffic generation and forecasts swp4.1 is almost independent of other work-packages and can be immediately started from the beginning of the study. This work package make use of the air traffic simulation tool NAVSIM. WP4.1 produce air traffic for the target years of the study (i.e. 2015, 2020, 2025, 2030, 2035, and 2040). Thereby, growth indicators of Eurocontrol s latest long term forecasts is used. The regular update of the long term forecast that predicts air traffic up to the year of 2035 is used. For air traffic beyond that time a different report issued by Eurocontrol is used to estimate air traffic for the year These reports contain different growth scenarios where the following is considered: Scenario A (global growth) optimistic air traffic growth Scenario C (regulated growth) median air traffic growth The output of this work-package consist of 18 data files (based on XML) characterizing the air traffic of the desired target years and growth rates. These files will be used as direct input for the performance evaluation. Deliverable D3 final report describe the methodology to extrapolate air traffic to future target years. Additionally, the gained results of the air traffic extrapolation is shown within this report. 125 of 151

129 swp4.2 VDL Mode 2 Network Simulation The VDL Mode 2 Network Simulation needs to provide an appropriate interface to configure the simulation in such a way that scenarios defined in WP3 comply with the capabilities of the simulator itself. That is, the configuration of a ground based network including VDL Mode 2 ground stations and frequency deployment options. TheVDL Mode 2 Network Simulation make use of the Aeronautical Network Simulator which is capable to simulate multiple different protocols given an appropriate topology. For this study the VDL Mode 2 protocol is required to be implemented and integrated into the Aeronautical Network Simulator. Thereby, the data exchange and link management procedures are of interest. Additionally, the Physical channel is simulated (i.e. interference caused by neighboring stations is reflected in the simulation). This VDL Mode 2 implementation will benefit from the VDL Mode 2 evaluation carried out in a co-operation with EuroControl from 2002 until The output of this work-package is a set of data files (based on XML) which are further processed by the statistical analysis tool. The amount of produced data files is dependent on the amount of evaluation scenarios which will be evaluated during the course of the study. The files contain all relevant information necessary to assess the simulation runs of a specific scenario appropriately (a single scenario consist of multiple runs based on different frequency deployment options elaborated in WP3). As such the required input for this work package is an appropriate scenario description in form of a configuration file. The VDL Mode 2 protocol conformance is verified through appropriate test procedures available within the SARPs of VDL Mode 2. swp4.3 VDL Mode 2 Operational and Technical Constraints swp4.3 reflect any know issues of VDL Mode 2 (i.e. experience gained by ANSPs during operation). Especially current practice of LINK shows two effects which have significant impact on data throughput over VDL Mode2. One is related to the hidden ground transmission effect, which causes collisions of ground data transmissions at the airborne receiver side. This is due to the CSMA channel access scheme used in VDL Mode2 and the fact that ground transmissions cannot be treated as a cluster for several VGSs in place. The second effect is due to the implementation of selection of VGSs by the airborne radio. It turned out that not always the most logical selection is in place. A consideration of this effect might be useful to provide some guidelines for airborne radio manufacturer. swp4.4 Statistical Evaluation and Reports Generation swp 4.4 cover the implementation of a statistical evaluation and report generation tool. Thereby, produced output (in form of XML) is used as input to analyze required performance figures. A template is produced and documented in the form of deliverable D1.2 Simulation Results Template. All subsequent simulation reports is based on that template. The auto-generated reports is compatible with MS Word. swp4.5 Validation of evaluation concept swp4.5 constantly monitor and validate the simulation approach. That means that the implemented model and parameters of the evaluation environment is cross-checked with the information provided by partners. swp4.6 Final Report Production swp 4.6 produce a final synthesis report, reflected on the deliverable D3. This document is created bringing together the analysis of all scenarios defined on WP3, executed on WP 4.4 and validated by all consortium partners on WP 4.5. All relevant key metrics are detailed and as output a traceability matrix between operational improvements and technological enables is realized, highlighting the breaking point of VDL Mode 2 technology (standard and myltifrequency) and foreseen needed requirements on future datalink technologies. ENAV leads this sub-work Package, with the contributions of all the consortium partners. 126 of 151

130 A.2 Deliverables Deliverable D0 - Detailed Project Plan Deliverable D1.1 - Detailed Specification of the Baseline Scenario Deliverable D1.2 - Simulation Results Template Deliverable D2.1 - Overview Simulation Results A.3 Schedule Figure 86 - GANTT of the project 127 of 151

131 Appendix B SESAR_CFT_0096 Edition During the introduction of new standards for data communication in aviation (i.e. mainly VDL mode 2, mode 3, and mode 4) a lot of research on the topic of VDL Mode 2 has been published; a paper called characteristics and capacity of VDL Mode 2, 3, and 4 sub-networks gave a good overview of the performance of each of those systems. Also, Eurocontrol conducted a study called VDL Mode 2 Capacity Simulations Project and published results in late 2006Error! Reference source not found.; USBG was part of this study. Figure 87: High Level view of simulation tool chain The approach of the is based on a simulation tool chain where each element provides input to the next element of the chain. Each tool is based on a discrete event based simulation. The first tool (NAVSIM 37 : Air Traffic Calculation) provides the mobility of aircraft of a complete day 38 (i.e. 24 hours). The information of each aircraft is updated in discrete steps of 3 seconds 39. Thereby, important aspects such as position (i.e. longitude, latitude, and altitude), vertical intent, current 37 NAVSIM ATM/ATC/CNS Simulation Tool developed by Mobile Communications R&D (MCO) in close co-operation with University of Salzburg (USBG) 38 based on data provided by Eurocontrol/NM (former CFMU) for a reference day (whole ECAC area) 39 might be simulated or derived (interpolated) from time steps of about 1 minute (e.g. Consolidated Position Report (CPR) data) 128 of 151

132 domain (i.e. APT, TMA, ENR, or ORP), and current sector information are provided. Aircraft are generated for the core area of Europe. The amount of aircraft is extrapolated to the desired scenario (i.e. year and growth scenario). The second tool (VDL Mode 2 Topology Calculation) takes this information and calculates distances of individual aircraft to neighbouring aircraft and visible ground stations. The distances are updated in the same discrete steps as the granularity of the aircraft mobility model. Neighbouring aircraft are all aircraft which are within the radio horizon. The same is true for visible ground-stations. The second tool requires input data such as ground-station positions (latitude, longitude, and altitude), operating frequency, and parameters necessary for link budget calculation such as transmission power or antenna gain. Due to the geographical areas that have been assessed we did not consider any digital elevation model as obstacles are not expected within the evaluated area. The third tool (VDL Mode 2 Protocol and Channel Simulation) takes the mobility, topology, data model, and additional scenario configuration parameters and produces VDL Mode 2 performance data. Each simulation scenario is simulated with multiple different initial seed settings, thus providing confidence intervals for all results. The gained performance data is stored for each seed in a separate xml file. The fourth and final tool (VDL Mode 2 Report Generator) takes all performance data of a single scenario setup and calculates performance figures. These figures are then provided in separate simulation reports. These reports are auto-generated. For concluding comparisons the VDL Mode 2 Report Generator keeps data of interest for the final report. B.1 Mobility Model Eurocontrol has provided an update of the long term forecast that predicts air traffic up to the year of 2035 [c.f. GROWTH REPORT 2035]. For air traffic beyond that time a different report issued by Eurocontrol can be used to estimate air traffic for the year 2040 [c.f. GROWTH REPORT 2050]. These reports contain different growth scenarios where the following is considered: Scenario A (global growth) optimistic air traffic growth Scenario C (regulated growth) median air traffic growth The extrapolated air traffic including position data (latitude, longitude, and altitude), flight domain, and sector information form the mobility model of the study. This methodology has been applied for previous projects and is applied for this study as well. In order to simulate and produce air traffic profiles for dedicated areas and future reference scenarios a simulation tool is necessary. The approach and methodology to extrapolate air traffic to future target years has been successfully applied in the past. This section describes the capabilities of the air traffic model and shows pragmatically the approach to extrapolate air traffic of today to the future based on the simulation tool NAVSIM. The NAVSIM tool is capable to simulate all phases of flight (i.e. Communications at departure gate (1), during taxiing (2), Take-Off (3), On Departure Route SID (4), En-Route (5), Arrival STAR, Approach and Final Approach (6), Landing (7), Taxiing (8), Communications at destination gate (9)) taking the characteristic performance data of each aircraft type (based on Base of Aircraft Data (BADA 40 ) data) into account. This allows simulating accurately the time instances an aircraft remains within the various domains (i.e. Airport (APT), Terminal Maneuvering Area (TMA), and En-route (ENR) also including Oceanic Remote and Polar (ORP) regions). Air traffic (consisting of several thousands of aircraft) is usually simulated with time steps of around one second and can be simulated in a very detailed approach for microscopic scenarios (i.e. APT and TMA areas) where intervals of position updates can be rather short (smaller than 50 milliseconds). For large scale evaluations air traffic (consisting of several ten-thousands of aircraft and up to around aircraft for a worldwide scenario) is simulated in a coarse-grained approach (position updates larger than 3 seconds) of 151

133 Aircraft are created at departure airports 30 minutes before the Calculated Take-Off Time (CTOT). Briefly before take-off (i.e. during "taxiing") the aircraft moves toward the runway. Take-off, climbing, cruising, and descending behavior are based on the aircraft type. The flight track an aircraft is flying is according to a known flight plan from which the actual flight path is derived, emulating a generic Flight Management System (FMS) for each aircraft. After landing the aircraft is deleted from the simulation around 15 minutes after touchdown. In addition to all phases of flight, performance based flight characteristics, and realistic flight tracks NAVSIM can also provide information about the ATC sectors (which is important for ATC data application triggers). The NAVSIM tool is simulating air traffic based on scheduled flights. Data on scheduled flights is retrieved from Eurocontrol Network Operations (formally called Central Flow Management Unit (CFMU)) for specific reference days. Data for a reference day (around flights) contain all flights within the ECAC (European Civil Aviation Conference) area, but also all flights outside the ECAC area if the flight departs from, arrives at, or overflies the ECAC area. In order to generate future air traffic based on this data the following steps are conducted: 1.) Generate a reference day based on data from Eurocontrol Network Operations 2.) Evaluate growth factors based on Eurocontrol s long term forecasts (from STATFOR) 3.) Include additional flights to reference day based on a specific algorithm (explained below) 4.) Validate retrieved results (through comparison with output of Eurocontrol s SAAM tool) STEP 1: Simulating future air traffic requires the generation of individual future flights. For this reason an approach has been developed, which is based on the air traffic of a reference day with the following main characteristics: Detailed statistics of all flights of the reference day are available, including especially all departure / destination airport pairs (flight relations) for each country in the area of interest. For each such flight relation the number of flights in both directions is available. All future air traffic scenarios are an extension of the reference day s traffic scenario, i.e. each individual flight of the reference day is also contained unchanged in the future scenario. STEP 2: Eurocontrol s long term forecasts provide individual air traffic growth factors for each European country. Based on the reference day s air traffic the following parameters need to be assessed: Growth factor of each individual country Total flights within each country (i.e. departure and destination pair is within same country) Total number of flights to other countries Total number of flights between each flight relation in either direction STEP 3 Based on steps 1 and 2 an extension factor can be calculated. This extension factor is a separate multiplication factor for national flights and for international flights of a specific country, respectively. The calculation is done in the following way: Considering flight relations between two countries, the lower growth rate is taken to increase the number of flights between the two countries in question. Running this calculations for all country pairs in the area of interest results in a growth rate that is still too low (as the minimum growth rate is considered for each relation). In order to achieve the target growth rate for each country the required number of additional flights within the country in question is calculated. 130 of 151

134 From this the total number of future flights and the future extension factor is calculated for each pair of countries (including flights within each country). As a result, future air traffic scenarios can be generated satisfying the individual air traffic growth rate of each country in the area of interest. STEP 4: To validate the results, the number of flights in the simulation for each country and each air traffic scenario (2015 to 2040, Scenarios A, C and D) is compared with the number of flights for the reference day per country and applying a multiplication factor according to the growth rate as specified in the Eurocontrol / STATFOR Long-term forecast statistics for each country. Furthermore in the past the results for the year 2020 have already been validated with available data from Eurocontrol (SAAM 2020 scenario) and have shown a very good correspondence (in terms of Peak Instantaneous Aircraft Count (PIAC) for the ECAC area) between the NAVSIM/2020/Low D scenario and the SAAM data for the year NAVSIM is implemented in Delphi and runs on any Microsoft Windows platform. B.1.2 Air Traffic data file The air traffic reference (mobility) data has been provided on courtesy by Eurocontrol/NM. The following describes the main characteristics of the reference air traffic data: Reference Day: August 29 th, 2014 (last Friday in August; high/peak day of year 2014) Type of Flights: Number of Flights: Main data provided for each flight: All IFR Flights (within / to / from) ECAC area on reference day (within 24 hours) Callsign / Operator Type of Aircraft Departure and Destination Aerodrome ETD, CTD, ATD (Estimated, Calculated, Actual Time of Departure) ETA, CTA, ATA (Estimated, Calculated, Actual Time of Arrival) Flight Route by Point Coordinates (Latitude, Longitude and Altitude / FL) Flight Route by Air Space Profile (Entry / Exit Time) Based on STATFOR air traffic forecast data described above (year 2014 to 2040; Scenarios A, C and D), the following number of flights have been calculated for the whole ECAC area (within 24 hours) based on the reference day (August 29 th ) of the year 2014: Median Optimistic 2015 MOB_2015_M: 34,078 MOB_2015_O: 34, MOB_2020_M: 40,174 MOB_2020_O: 41, MOB_2025_M: 45,172 MOB_2025_O: 47, MOB_2030_M: 49,539 MOB_2030_O: 54, MOB_2035_M: 53,544 MOB_2035_O: 61, of 151

135 2040 MOB_2040_M: 58,693 MOB_2040_O: 70,319 Table 62: Expected number of flights of mobility scenarios from 2015 to 2040 The following figure shows the expected number of flights within the whole ECAC area for the years 2014 to 2050; Scenarios A, C, and D) based on the reference day (August 29 th ) of year 2014: Figure 88: Number of Flights within ECAC Area (peak day 2014; 2015 to 2050 (forecast)) B.2 Topology Model As depicted in the high level view of the simulation approach (c.f. Figure 87) it can be seen that the VDL Mode 2 topology calculation takes three data input sources: 1. The previously generated mobility model (containing all flights within the area of interest) 2. Ground station information (i.e. location of all European VDL Mode 2 ground stations) 3. Topology configuration data (i.e. diverse parameters) The topology model addresses the following aspects: 1. Area of interest used to evaluated performance characteristics 2. Ground station locations and characteristics 3. Link Budget model used to calculate interference 4. Mobility management used to determine handoff decisions 5. Deployment options used to analyse different frequency settings B.2.1 Area of interest Figure 90 gives an overview of the simulated reference area and the involved data link topology. The black lines indicate simulated air traffic tracks. The red ellipses show the areas of interest for a high data link usage environment (High density area) and a low data link usage environment (Rome area), 132 of 151

136 respectively. These areas are represented as ellipses as the Mercator projection distorts the circular area of interest with a radius of roughly 150 nautical miles. Each available VDL Mode 2 ground station within the simulated reference area is simulated, however, evaluated are only those which are located within the areas of interests for high and low data link usage, respectively. These ground station positions are represented as orange circles the remaining ground stations are represented as green circles. Figure 89: Number of flights on reference day (Aug. 29 th 2014). The areas of Lille and Rome have been selected to represent high and low data link usage environments, respectively. The area with high air traffic density is the area with roughly 150 nautical miles (nm) radius around Lille, France. All major airports within the capital areas of London, Paris, Brussels and Amsterdam lay within this area. Figure 89 highlights the number of flights within selected areas of interest. This figure clearly shows that the High density area contains most flights across Europe while Rome reflects an area with comparably low air traffic. 133 of 151

137 Figure 90: Simulated area including areas of interest with high and low data traffic. B.2.2 Ground Station characteristics The following tables indicated the ground station characteristics of the evaluated ground stations that are located within the two areas of interest. Code City Airport Country OWNER FRQ Power AMS7 Amsterdam Schipol Netherlands SITA 136, W BRU7 Brussels National Belgium SITA 136, W CDG7 Paris CDG France SITA 136, W CDX Paris CDG France SITA 136, W DUS7 Düsseldorf Int l Germany SITA 136, W LCY7 London City Airport UK SITA 136, W LGW7 London Gatwick UK SITA 136,975 5 W LHR7 London Heathrow UK SITA 136, W NWI7 Norwich Int l UK SITA 136, W ORY7 Paris Paris Orly France SITA 136, W PAR7 Paris No Airport France SITA 136, W PARU Paris No Airport France SITA 136, W Table 63: Evaluated SITA network relevant for area of interest with high data link usage Code City Airport Country OWNER FRQ Power AMS Amsterdam - Netherlands ARINC 136, W BRU Brussels - Belgium ARINC 136, W CDG Paris - France ARINC 136, W LGW London - UK ARINC 136, W LTN London - UK ARINC 136, W ORY Paris - France ARINC 136, W STN Paris - France ARINC 136, W Table 64: Evaluated ARINC network relevant for area of interest with high data link usage Code City Airport Country OWNER FRQ Power Ciampino - Italy ENAV 136, dbm 134 of 151

138 Code City Airport Country OWNER FRQ Power ATCR-33S FCO Italy ENAV 136, dbm SMR-B FCO Italy ENAV 136, dbm Napoli - Italy ENAV 136, dbm Table 65: Evaluated SITA & ARINC network relevant for area of interest with low data link usage NOTE 1: In Italy all ground stations are operated by ENAV, hence SITA and ARINC use the same access network to provide services to their customers. NOTE 2: The antenna radiation pattern is assumed to be omnidirectional for each antenna. That is, all aircraft that are in line of sight of an antenna are capable to receive signals from that ground station. NOTE 3: The listed power in the tables above is understood as EIRP. B.2.3 Link Budget Model The Signal in space minimum aviation system performance standards (MASPS) for advanced VHF digital data communications including compatibility with digital voice techniques VDL_MASPS describes the link budget for VHF Data Link in Appendix L. For this study it is reasonable to take this model as direct input for the simulation. Within this section the link budget calculations are described details can be found the previously mentioned document. B Link budget theory For any radio link, the achieved signal-to-noise ratio (SNR) determines the quality of the received signal. For radio systems using digital transmission techniques, the signal quality is normally expressed in terms of bit error rate (BER) or the packet error rate (PER), both of which are related to SNR by well-known formulations. The received signal level on VHF line-of-sight paths is given by P R PT GT GRλ = C 2 L L (4 πρ) T R 2 GT GR λ 1 = PT L L 4πρ L T R GR P where R and PT are the received and transmitted power respectively, GR and GT are the receive L and transmit antenna gain respectively, R and LT are the receive and transmit line losses respectively, λ L is the wavelength, and GR is the squared magnitude of a complex-valued term that accounts for interference between the direct line-of-sight and ground reflection paths. 2 The factor 2 λ 4πρ is the free-space propagation loss, which may be expressed in decibels as LFS ( ρ ) = log + 20log ( f ) of 151

139 where LFS is the free-space loss in decibels, ρ is line-of-sight distance (slant range) between the transmitter and receiver in nautical miles, and f is the operating frequency in Megahertz. Due to the fact that the free-space propagation loss can be assumed as worst case a different model has been applied. Namely, the propagation curves as recommended in the Recommendation ITU-R P (02/2012) Propagation curves for aeronautical mobile and radio navigation services using the VHF, UHF and SHF bands. LGR The term accounts for the combined effects of reflection from the Earth's surface and the dependence of the atmosphere's refractive index on aircraft altitude. These effects have been modelled in the Johnson-Gierhart model (refer to VDL_MASPS for more details). The error performance of the link is determined by the ratio of the average received power to the average noise power, that is, by the signal-to-noise ratio. This requires that we estimate the amount of noise present in the receiver signal processing bandwidth (again for more details refer to VDL_MASPS). B Link budget simulation For every simulated Node (ground station, aircraft) the received power level is calculated by summing up all currently available signals. In order to calculate the SNR, all other signals during a transmission are taken into account (these signals are considered as external noise). All undesired signals that are received during the time period of the desired signal (c.f. figure 65) are accumulated. The interfering signals are accumulated; however, the inference is accounted only for the amount of time the interference was present during the observed time period. In other words an average value is used. This is a valid approach as the physical layer applies code interleaving. Based on the retrieved signal to noise ratio it is possible to calculate the bit error rate for received physical frames. Interference 4 Interference 3 Desired SIGNAL Interference 2 Interference 1 Figure 91: Interference The distance between aircraft and neighbouring/visible ground stations and aircraft is always known during the simulation (based on line of sight calculations). The following steps is considered in order to determine whether a data packet is received correctly: 1.) If an aircraft or a ground station transmits data each neighbouring/visible ground station or aircraft knows the received power based on a link budget calculation. That is the SNR of each received data packet can be calculated. 2.) Based on known VDL Mode 2 performance (i.e. PER (based on code word length) to SNR) it is possible to determine the packet error rate. From the known PER error curve it is possible to derive an error probability for that specific packet. 3.) A random process decides if the packet is dropped 136 of 151

140 NOTE: It is assumed that the interference of different VDL frequencies is negligible. NOTE: It is assumed that interference is Gaussian distributed (i.e. SINR == SNR). In order to determine whether a channel is idle or busy a threshold is used. The received power (based on link budget calculation) is aggregated (linearly). If the threshold is exceeded the channel is sensed as busy. Ground Station Transmitter Power Ground Station Cable Loss Ground Station Antenna Gain Aircraft Transmit Power Aircraft Cable Loss Aircraft Antenna Gain Ground Station Receiver Noise Figure Aircraft Receiver Noise Figure External System Noise Figure Modulation 5W 50W (36dBm 47dBm) 4.5 db 0 dbi 15 W = 41.8 dbm 3 db -4 dbi 10 db 14 db 10 db D8PSK Channel Symbol Rate B.2.4 Mobility Management 10,500 symbols per second Table 66: Parameters used for link budget calculation. The mobility management determines the initial VDL Mode 2 ground station selection and the handover/hand-off procedures. The initial ground station selection algorithm is based on the best received signal. The procedure itself is based on the standard algorithm. The following information is considered for hand-over/hand-off: 1. Priority is given to VDL station declared as ATN capable (we consider all stations as ATN capable). 2. When a connection is established, there are 2 possible events that trigger a change: a. When the Quality of the signal is too low (i.e. SQP <= 3), or b. When the system fails to send a message after a certain number of attempts. That is, the N2 parameter is reached (N2 equal to 6). B.2.5 Deployment Options Four different deployment options are considered to address multi-frequency: Channel Data traffic carried by frequency Common Signalling Channel (CSC) data FRQ Option1 FRQ 1 Data traffic of aircraft that stay in the airport (APT) domain Data traffic of aircraft that are flying in the TMA/ENR domain Table 67: Frequency Option 1: Single frequency. 137 of 151

141 Channel Data traffic carried by frequency Common Signalling Channel (CSC) data FRQ 1 Data traffic of aircraft that stay in the airport (APT) domain FRQ Option 2 Data traffic of aircraft that are flying in the TMA/ENR domain FRQ 2 Data traffic of aircraft that stay in the airport (APT) domain Table 68: Frequency Option 2: Multi frequency deployment with two frequencies. Channel Data traffic carried by frequency Common Signalling Channel (CSC) data FRQ 1 Data traffic of aircraft that stay in the airport (APT) domain FRQ Option 3 Data traffic of aircraft that are flying in the TMA/ENR domain FRQ 2 Data traffic of aircraft that stay in the airport (APT) domain FRQ 3 Data traffic of aircraft that are flying in the TMA/ENR domain Table 69: Frequency Option 3: Multi frequency deployment with three frequencies. Channel Data traffic carried by frequency Common Signalling Channel (CSC) data FRQ 1 Data traffic of aircraft that stay in the airport (APT) domain FRQ Option 4 Data traffic of aircraft that are flying in the TMA/ENR domain FRQ 2 Data traffic of aircraft that stay in the airport (APT) domain FRQ 3 Data traffic of aircraft that are flying in the TMA/ENR domain FRQ 4 Data traffic of aircraft that stay in the airport (APT) domain Table 70: Frequency Option 4: Multi frequency deployment with four frequencies. The algorithm to select a VDL Mode 2 frequency in one of the Multi-Frequency (MF) scenarios is implemented as follows: An airborne VDL Mode 2 station (aircraft) always logs onto the VDL Mode 2 network via the Common Signalling Channel (CSC; MHz) responding to the periodically transmitted Ground Station Information Frames (GSIF). Then the VDL Mode 2 ground station decides on which frequency the further communication data exchange is carried out. For all aircraft in the airport domain (APT) either the CSC or one of the APT frequencies is chosen. This selection is based on the lowest number of aircraft allocated to a specific ground station. In case that the airborne VDL Mode 2 station (aircraft) is within the TMA/ENR domain during the initial establishment of the VDL Mode 2 connection via the Common Signalling Channel (CSC) - on request of the VDL Mode 2 ground station the aircraft is either handed over to the VDL Mode 2 frequency foreseen to handle TMA/ENR data traffic or stays on the CSC. As explained above, this decision is based on the current lowest number of aircraft allocated to the VDL Mode 2 ground stations in question. In case that the domain in which an aircraft is already in (either airport (APT) domain or TMA/ENR domain) changes, that is either from APT domain to TMA/ENR domain (initial phase of a flight) or from TMA/ENR domain to APT domain, the VDL Mode 2 ground station decides whether a handover has to be carried out as follows: Current domain Next domain Current frequency Next frequency Remark APT TMA/ENR CSC CSC or TMA/ENR APT CSC or TMA/ENR TMA/ENR APT CSC CSC or APT APT could be one of two APT frequencies TMA/ENR CSC or APT APT could be one of two APT frequencies 138 of 151

142 The decision which VDL Mode 2 frequency to chose (CSC, APT or TMA/ENR) again depends on the lowest number of aircraft currently allocated to the target (next) frequency. B.3 Data Application Model The data application model needs to represent a realistic system load. The intention of this data model is not the implementation of an interactive application processes. However, the attempt is to model the load as realistically as possible. The generation of data application messages is based on the flight path of simulated aircraft. That means, all phases of flight are reflected in simulated flight paths. In order to trigger data applications at the right simulation time of a flight it is necessary to identify possible trigger events for data applications of simulated flights. Trigger Events can be: - Change of ATC domain (APT arr., APT dep., TMA arr., TMA dep., ENR, ORP) - Change of ATC sector - Change of vertical intent (i.e. cruise, climb, descend) not considered in this simulation - Change of APT position (i.e. Ramp, Ground, Tower) not considered in this simulation APT TMA ENR TMA APT Instance 1 Instance 2 Ramp Ground Tower Sector 1 Sector 2 Sector n Instance 3 Tower Ground Ramp Possible Triggers Figure 92: Possible trigger events of a simulated flight. Based on the Trigger Event it is possible to derive a time window within the simulation. Figure 92 represents this time window as Instance. That is, after a Trigger Event happens it is possible to schedule message exchanges within this window. An application instance contains of 1 to n dialogues, where a dialogue may consist of 0 to f Forward Link FL messages and 0 to r Reverse Link RL messages (Figure 93). An aeronautical data communication service may start its dialogues within a service instance either at the beginning, at the end, or (in absence of a specification) at a random point during the service instance duration. If a service instance consists of more than one dialogue the dialogues are evenly distributed with a random offset (up to +/-10% of the service instance duration). 139 of 151

143 Figure 93: Application instance and corresponding dialogues. Forward link and reverse link messages may be separated by the human interaction time HIT (if applicable) and the Required Communication Technical Performance RCTP one way latency. The RCTP is the required 95% percentile latency of any aeronautical data link technology. The maximum execution time is calculated through the separation time of consecutive forward link and reverse link messages. This interval time is calculated through the RCTP one way latency and (if applicable) HIT multiplied by two (Figure 94). This models an interactive application data exchange (i.e. a message and a response) performed over a data link technology providing the minimum latency requirements which are defined by the RCTP. The human interaction time is only included if the application message generation is human dependent. Forward L. (RCTP+HIT)*2 Reverse L. RCTP+HIT (RCTP+HIT)*2 B.3.1 ATS data traffic Figure 94: Calculation of maximum execution time for a dialogue Current air traffic control is based on voice exchanges between aircraft crew and air traffic controllers. In order to introduce data link communication utilized for air traffic control aircraft and air traffic control canters need to be equipped in terms of hardware and software, respectively. Currently the vision is that data link is introduced for air traffic control in 3 phases. These phases are realized through programs called ATN B1, ATN B2, and ATN B3. Assumptions with respect to ATS datalink program: 100 % ground equipage rate. That is, if aircraft are capable to use ATN B 1/2/3 data link message exchanges, they is able to use it at any time. If aircraft are capable to use ATN B2 they will use only the defined set of message for ATN B2. If aircraft are capable to use ATN B3 they will use only the defined set of message for ATN B3. FANS 1/A communications over VDL Mode 2 are assumed to behave as ATN communications. The following table indicates the equipage rate with respect to all simulated flights assumed for the different simulated years: ATS ATN B1 80 % 100 % 100 % 100 % 100 % 100 % 140 of 151

144 ATS ATN B2 0 % 0 % 20 % 80 % 100 % 100 % ATS ATN B3 0 % 0 % 0 % 0 % 20 % 80 % ATS Communication profile B1 Assumptions on application data messages simulated for ATS data traffic. ATN B1 communication profile 2015 (ENR only) o Transfer of communication (1 UL and 1 DL) per sector (approximately every 6 min) o clearance (1 UL and 1 DL) per sector (approximately every 6 min) o message size: 200 byte ATN B1 communication profile from 2020 onwards (ENR only) o Transfer of communication (1 UL and 1 DL) per sector (approximately every 6 min) o 3 messages (1 UL and 1 DL) per sector (approximately every 6 min) NOTE: Message size is assumed to be constantly 200 bytes. ATS Communication profile B2 / B3 Note: The above mentioned model is applied to produce application data according to the characteristics presented in the table below. These applications are valid for both ATN B2 and ATN B3, respectively. However, performance requirements are more stringent for ATN B3 applications. 141 of 151

145 Table 71: ATS Communication profile B2 / B3 B.3.2 AOC data traffic The AOC data model assumptions are based on input received from SITA. The model is based on the subscription status, which can be small, medium, or large, respectively. In this case a small subscription means the lowest amount of message and data volume exchange, respectively. The message sizes itself are determined by an accompanied empirical histogram (this data is confidentially provided by SITA). In order to extrapolate the data from now to 2040, the current (2014) data has been compared to the data from Assuming a linear growth the following numbers represent the amount of AOC data message exchanges used for the simulation. 142 of 151

146 Figure 95: AOC application message exchanges for different subscriber levels. The following table show the interpolated amount of AOC messages assumed to be exchanged between air and ground for the years 2020 to Thereby, historic data is being used as basis. The different columns indicated the flight phase and subscription level (i.e. small, medium, and large). 143 of 151

147 144 of 151

148 Figure 96 - AOC messages assumed to be exchanged between air and ground for the years 2020 to 2040 B.3.3 End-to-End TRTD estimation In order to estimate the Technical Round Trip Delay (TRTD) 41 of ground initiated ATS/CPDLC messages, taking into account the whole communication link from the ground based application (e.g. CPDLC message generation by Air Traffic Controller (ATCO)) in the ATN ground network 42 through the VDL Mode 2 radio access network to the airborne application (e.g. FMS display) connected to the aircraft (on-board) network and vice versa (ACKs) on application (end-to-end (TP4) level the following VDL Mode 2 Markov Model has been developed, which is based directly on the simulation results of the detailed VDL Mode 2 simulations carried out in the context of this study. Namely the following parameters are taken explicitly into account: TD_UL... Uplink (UL) "one-way" transmission delay, composed of medium access control (MAC) delay (i.e. the delay to get access to the radio channel) and the transmission delay from sending the message until it is received successfully at the receiving station; TD_DL... Downlink (DL) "one-way" transmission delay, in the reverse direction (from airborne application to ground application); RTO_UL... Standard Retransmission Timeout value based on Karn's algorithm; in the Markov model it is twice the round trip transmission delay composed of uplink and downlink "one-way" transmission delay; Retransmission algorithm: if a CPDLC message which was transmitted on the uplink is not (by receiving an ACK) before the retransmission timer (RTO_UL) expires, a 41 Technical Round Trip Delay (TRTD) of ATS/CPDLC messages as specified in "Link DLS CRO Performance Monitoring Requirements", Eurocontrol / Network Manager Directorate, David Isaac, Ed. 1.3, 19 May ATN... Aeronauical Telecommunication Network 145 of 151

149 retransmission of the un CPDLC message occurs; this retransmission timeout value is increased by a factor of 2 with each subsequent retransmission 43 ; p_lossul.. probality of loss (loss rate) on the uplink; p_succul... probability of success (success rate) on the uplink = 1 p_lossul; p_lossdl.. probality of loss (loss rate) on the downlink; p_succdl... probability of success (success rate) on the downlink = 1 p_lossdl; t... Time step of the Markov model corresponding to the Minimum(TD_UL,TD_DL); in the outline of the Markov model above it is assumed that the transmission delay on the downlink is smaller than the transmission delay on the uplink; By calculating a transition probability matrix P between each of the states of the VDL Mode 2 Markov model (see VDL Mode 2 Markov model for details) and multiplying this transition matrix n times, i.e. P n, we get an estimate for the probability that within n time steps ( t) the transition from the initial state 0 (UPLINK) to the success state 16 (ACK RECEIVED) is reached. From this calculation it can be estimated which percentage of transmitted CPDLC messages is successfully after e.g. 16 seconds (max target value for 95 th percentile for TRTD) or after 20 seconds (max target value for 99 th percentile for TRTD). It should be further noted that a fixed round trip transmission delay of 2 seconds is assumed for the ATN ground network, while the round trip delay within the airborne network is assumed to be neglectable. 43 In the VDL Mode 2 Markov model the retransmission timeout value is increased by a factor of 2 until a maximum value of 4*RTO_UL is reached; subsequent retransmissions use the same retransmission timeout value. 146 of 151

150 Figure 97: Markov Model to estimate Technical Round Trip Delay (TRTD) for end-to-end data traffic. B.4 Protocol Simulation The VDL Mode 2 simulation software reflects the Standard and Recommended Practices (SARPs) of VDL Mode2. The core components of the simulation software are the Medium Access layer and the Data Link Layer. The primitives exchanged between the entities of the sub-layers is used in order to model system behavior rather precise (c.f. Figure 98). Starting from the Physical Layer it is important to model the free space propagation of radio signals in such a way that neighboring entities are receiving data packets at different points in time. Therefore, it is necessary to know the distance between entities at any time of the simulation. This provides the possibility to indicate toward the VDL Mode 2 Physical Layer of each simulated entity (i.e. a mobile station or a ground station) whether the physical channel is idle or busy. The reception and transmission of data packets is also supported through such an approach. Each simulated entity (i.e. a mobile station or a ground station) provides a model representing the Radio Spectrum. This allows every simulation entity to schedule a Start of Data Reception event and an End of Data Reception event at its neighbors (i.e. simulation entities that are within a reasonable range). Additionally, a Transmission garbled event can be scheduled by transmitting data stations at neighboring simulation entities. In such a way it is possible to determine whether data packets are destroyed due to channel contention or not. Based on the known distance among each other, also the quality of the signal can be determined. Based on this information it is easy to model the Medium Access (MAC) sub-layer according to SARPs. However, it has to be noted that the performance of the VDL Mode 2 MAC sub-layer is dependent on many factors (e.g. initial parameter settings and current load). 147 of 151

151 The Data Link Service (DLS) entity provides connection oriented data transfer (based on HDLC). The Logical Link Layer (LLC) provides connectionless data transfer (for broadcast messages). The Link Management Entity (LME) is included in the VHF Management Entity which provides an interface to upper layers for initialization and shutdown of the service. The Sub-network entity provides an interface for connection oriented and data transfer. For connectionless and un data transfer the LLC provides an interface toward upper layers. The VDL Mode 2 protocol implementation correctness has been verified through multiple unit test cases proposed within the standard documentation itself (c.f. Appendix to Part I of Manual on VDL Mode 2 [ICAO]). As a result of this verification effort it can be assumed that the VDL Mode 2 protocol simulation software is working appropriately to the greatest possible extent. A simulation management interface starts and stops the VHF management entity which is responsible for initial ground station logon and handoff/handover decisions. Generated application data packets are directly handed over to the VDL Mode 2 layer. A simple first in first out queue takes care that data packets are not flooding the system. That means, no transport layer protocol is simulated. However, the end to end performance can still be evaluated based on the obtained Layer 2 performance. 148 of 151

152 DL_DATA.req LM_DISC.ind DL_DATA.ind LM_STARTUP.req LM_SHUTDOWN.req PH_SQP.ind DL_RST_N2.ind DL_RST_TM2.ind DL_RST_FRMR.ind DL_RST_DISC.ind DL_XID.ind DL_RST_N2.ind DL_RST_TM2.ind DL_RST_DM.ind DL_BLOCK.req DL_UNBLOCK.req DL_DISC.req DL_DATA.req DL_RST_DM.req DL_XID.req DL_UNITDATA.req PH_DATA.ind PH_OCC.ind TX_EVENT _TM2.ind TX_EVENT _TM2.ind PH_DATA.ind PH_OCC.ind TX_QUEUE.req TX_QUEUE.req MA_CTS.ind MA_EVENT_TM2.ind MA_RTS.req PH_ADD.req PH_FREQ.req PH_DATA.req PH_IDLE.ind PH_BUSY.ind RF_OCC.ind RF_BUSIY.ind RF_IDLE.ind RF_PDU.rcv RF_PDU.xmt Figure 98: Simulation protocol stack of VDL Mode 2 performance and capacity study 149 of 151

153 Appendix C SESAR_CFT_0096 Edition See SESAR JU extranet for all the material produced during simulation runs. 150 of 151

154 -END OF DOCUMENT- 151 of 151