AERONAUTICAL COMMUNICATIONS PANEL (ACP)

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1 International Civil Aviation Organization WORKING PAPER ACP/1-WP/20 7/5/07 English only AERONAUTICAL COMMUNICATIONS PANEL (ACP) FIRST MEETING Montréal, 10 to 18 May 2007 Agenda Item 1: Review of the progress on the future communication study EUROPEAN TECHNOLOGY ASSESSMENT - STEP 2 ASSESSMENT (Presented by J. Pouzet) SUMMARY This working paper presents the activities currently underway in Europe to assess candidate future technologies. In particular the paper provides information on the methodology to assess candidate technologies against a set of criteria. Action by the ACP is in paragraph INTRODUCTION 1.1 The second step (Step 2), which is currently underway, is conducting further, in-depth evaluation of the Step 1 short-listed technologies or evolutions of them. The Step-2 process is identifying how and where each technology could be applied, and how they would perform in a typical operational environment. This entails a more detailed assessment of performance and characteristics of the candidate technologies identified in the Step 1 report (ACP/1-IP/4 refers). 1.2 To compare the suitability of technologies to meet the requirements an assessment methodology has been developed which is described in this paper. The detailed report describing the Step 2 assessment methodology is appended in this paper. 2. METHODOLOGY 2.1 In developing the assessment process and associated criteria the following points were considered: (33 pages) ACP.1.WP en.doc

2 ACP/1-WP/ a) the process had to be transparent, understandable; b) the key (essential) criteria which candidate technologies must meet have been identified; and c) a set of desirable features has been identified against which the technologies can be ranked. 2.2 The assessment process applies the essential criteria to the selected technologies to identify those that meet the basic needs. In addition desirable features are evaluated in the detailed technology assessment phase and a ranking of the technologies is provided. A key input to the process is the ability of the technologies to meet the basic capacity requirements defined in the Evaluation Scenarios document (ACP/1-WP/21 refers). 2.3 Two essential criteria have been defined: d) spectrum compatibility in the target band of operation; and e) openness of the standard. 2.4 The desirable criteria are being used to help rank the candidate technologies against the key requirements. Two subsets of the desirable criteria have been defined: a) general criteria which covers the robustness of the RF signal, technology readiness level, flexibility and cost; and b) performance based criteria in each airspace type covering capacity, integrity, availability, and latency. 2.5 The assessment process is now being applied to technologies identified below. It should be noted that in the course of the Step 2 assessment some technologies have been renamed to those identified in the Step 1 results. These renamed technologies are not new technologies as they are based in the work and developments of their predecessors. LDL (L band datalink) was formerly referred to as (x)dl3 and B-AMC (Broadband Aeronautical Mobile Communications) is based on the B-VHF system but operating in the L-band. Additionally, two technologies in the Step 1 shortlist have been merged. The technology now called AMACS (All-purpose Multi-channel Aviation Communication System) combines the best features of the ETDMA and (x)dl4 system. 2.6 The list of the technologies being currently assessed in Europe as part of the Step 2 investigations and technology assessment is shown in the table below. Evolution of existing aeronautical systems or concepts: Terrestrial systems Satellite systems LDL AMACS B-AMC WCDMA P34 INMARSAT SwiftBroadband

3 - 3 - ACP/1-WP/20 New satellite systems Airport/surface systems IEEE e 2.7 It is planned to provide the final outcome of the assessment in the next WG-C meeting in September ACTION BY THE ACP 3.1 The ACP is invited to consider the information provided herein and to provide comments.

4 ACP/1-WP/20 Appendix APPENDIX EUROPEAN ORGANISATION FOR THE SAFETY OF AIR NAVIGATION

5 EUROPEAN ORGANISATION FOR THE SAFETY OF AIR NAVIGATION EUROCONTROL Future Communications Infrastructure - Technology Investigations Technology Assessment Methodology Edition Number : 0.9 Edition Date : 01/05/07 Status : Draft Intended for : EUROPEAN AIR TRAFFIC MANAGEMENT PROGRAMME

6 DOCUMENT CHARACTERISTICS TITLE Future Communications Infrastructure - Technology Investigations EATMP Infocentre Reference: Document Identifier Edition Number: 0.9 Edition Date: 01/05/07 Abstract This document describes the methodology to assess candidate technologies as part of the Eurocontrol/FAA Future Communication Study. Keywords future communication technologies FCI evaluation Datalink COCR Terrestrial systems Satellite systems aeronautical communications shortlist Requirements spectrum AMSS/AM(R)S Contact Person(s) Tel Unit Nikos Fistas DAP/CSP STATUS, AUDIENCE AND ACCESSIBILITY Status Intended for Accessible via Working Draft General Public Intranet Draft EATMP Stakeholders Extranet Proposed Issue Restricted Audience Internet ( Released Issue Printed & electronic copies of the document can be obtained from the EATMP Infocentre (see page iii) ELECTRONIC SOURCE Path: P:\EATM\DAS\BD_CSM\CMU\FUTURE_COM\Technology investigations\step 2\Step 2 method development Host System Software Size Windows_NT Microsoft Word Kb Page ii Draft Edition Number: 0.9

7 EATMP Infocentre EUROCONTROL Headquarters 96 Rue de la Fusée B-1130 BRUSSELS Tel: +32 (0) Fax: +32 (0) Open on 08:00-15:00 UTC from Monday to Thursday, incl. DOCUMENT APPROVAL The following table identifies all management authorities who have successively approved the present issue of this document. AUTHORITY NAME AND SIGNATURE DATE Please make sure that the EATMP Infocentre Reference is present on page ii. Quality Manager Hd Communications Domain Jacky Pouzet Hd CSP Rob Stewart Edition Number: 0.9 Draft Page iii

8 DOCUMENT CHANGE RECORD The following table records the complete history of the successive editions of the present document. EDITIO N NUMBE R EDITION DATE INFOCENTRE REFERENCE REASON FOR CHANGE PAGES AFFECTED 0.a Sept 06 Original All 0.d Nov 06 Modification following ACP Co-ord mtg. All 0.e Dec 06 Further comments incorporated All 0.f Jan 07 Further comments incorporated All 0.g April 07 Further comments incorporated All 0.9 May 2007 Released version to ACP/1 All Page iv Draft Edition Number: 0.9

9 CONTENTS DOCUMENT CHARACTERISTICS... II DOCUMENT APPROVAL... III DOCUMENT CHANGE RECORD... IV 1. INTRODUCTION Future Communication Study Action Plan Two Step Approach to Technology Assessment Step Step Document References STEP 2 METHODOLOGY List of technologies to be assessed Performance Requirements TECHNOLOGY ASSESSMENT Introduction Assessment Categories ESSENTIAL CRITERIA Compatibility within the target band RF interference rejection / signal robustness Transmitter Power Control... Error! Bookmark not defined Openness of the Standard DESIRABLE CRITERIA Generic Criteria Performance based Criteria Generic Criteria Performance Based Criteria Ranking Classes Masks Class 1 Mask Class 2 Mask Class 3 Mask Class 4 Mask Edition Number: 0.9 Draft Page v

10 3.6.7 Comparison of technologies CONCLUSIONS Page vi Draft Edition Number: 0.9

11 1. INTRODUCTION 1.1 Future Communication Study Action Plan 17 EUROCONTROL and the FAA initiated a joint study under a Memorandum of Co-operation (MoC) through a dedicated Action Plan (AP 17) to identify potential future communications technologies to meet safety and regularity of flight communication requirements, i.e. those supporting Air Traffic Services (ATS) and safety-related Aeronautical Operational Control (AOC) communications. This work is being input to the ICAO ACP/WGC and ACP/WGW to ensure a global consultation. The Future Communication Study (FCS) consists of two main sets of activity: 1. A study to identify future communication requirements. This activity is covered by the Communication Operating Concept Requirements (COCR) document. 2. A Technology Assessment to identify the most appropriate technologies to support these communication requirements. This document describes the assessment methodology to assess candidate technologies and produce a relative ranking between them. In Europe, EUROCONTROL has established the Air Ground Communications Focus Group (AGCFG), which provides a forum for European stakeholders to discuss future aeronautical communications, review progress and advise the EUROCONTROL Agency. In addition, EUROCONTROL has been working very closely with the active European ACP/WGC members (France, Germany, Spain, Sweden and UK). This work is being carried out to produce options for the Future Communications Infrastructure (FCI). In line with recommendations from the 11th Air Navigation Conference (ANC), the goal of the Future Communication Infrastructure (FCI) is to meet future aeronautical communication requirements with a minimum set of technologies deployed globally. The FCI will be a main enabler for new ATM services and applications that will bring operational benefits in terms of capacity, efficiency and safety. The FCI will support both data and voice communication with an emphasis on data communication in the longer term. The FCI must support new operational concepts that are being investigated and researched throughout the world as well as the emerging requirements for both voice and data communications of all types. The FCI will be the minimum set of technologies needed to meet the future requirements globally. New technologies as well as system strategies must be identified to support the FCI. This may include concepts for new communication technologies as well as multi-function equipment that can be tailored to operate in differing operational environments. Indeed, although the goal is to develop global standards, it might happen that availability of different systems with their own performance, cost, spectrum, transition and characteristics would be necessary to provide the required services in different types of airspace (e.g. continental, oceanic) and therefore a single universal solution may not be achievable. Edition Number: 0.9 Draft Page 1

12 As documented in the work of the AGCFG 1, the aeronautical communication requirements in the future are expected to include: voice and data communications; air/ground (a/g) and air/air (a/a) communications; addressed and broadcast /multicast communications; cockpit communications (ATS and AOC); other ATM exchanges (SUR, NAV, SAF/SEC info etc); if required from the business point of view, cabin (AAC and APC) communications, with the appropriate priority and pre-emption facilities for the safety/regularity of related ATS/AOC services. As documented in the work of the AGCFG the key drivers for the FCI are: support the future ATM communications requirements, as required in all phases of flight; employ technology in a way that is transparent to the user; avoid single points of failure affecting simultaneously the various types of communication enable smooth transition and provide support for legacy systems (backward compatible); be implementable (time and space) in a phased manner and be globally applicable (if so required); include provision(s) for growth in capabilities; maximise synergies (telecomm, military) and maximise reuse of available technology; be spectrally efficient; be cost-beneficial; make efficient use of existing and already planned infrastructure; if required, use different technologies for different phases of flight and/or applications. 1.2 Two Step Approach to Technology Assessment Following discussions, agreement was reached with the European ACP members to work on a two-step technology selection approach. In the first step the focus was on selecting the technologies using a subset of the initially considered criteria, for which their applicability can be more easily agreed. For this subset it was agreed to consider the separate COCR requirements for air/ground, air/air and broadcast services and establish a list of promising technologies. In the second step, additional considerations/investigations covering the concerns covered by the other initial selection criteria will be applied to the Step 1 selected technologies, aiming to produce a further short list and recommendations for implementation. 1 AGCFG: Key terms and definitions, v1.3 Page 2 Draft Edition Number: 0.9

13 The next two sections describe the proposed methodology in the various steps. This report provides a high level indication of the proposed work for step 2, which shall be updated as Step 2 work is carried out Step 1 The agreement for the first step was that the re-evaluation will focus on providing information on the capabilities of the candidate technologies to meet a reduced set of criteria composed of capacity (throughput) and QoS (i.e. Continuity, Integrity and Availability). The evaluation investigated the technologies considering two aspects. The first one was the capability to support the different type of services such as a/g and a/a and broadcast and addressed. The second one was the capability to operate in various type of airspace such as high and low density, en-route, TMA etc. The requirements for the parameters forming the reduced set of criteria are extracted from the COCR and then matched to those able to be supported by the candidate technologies in different airspace and for the different services. The Step 1 analysis [2] concluded with a list of promising technologies, with identification of their area of applicability (in terms of services and airspace) and list of further investigations that need to be undertaken for each of the technologies in the Step 2 to complete the technology assessment Step 2 The remainder of this document defines the methodology to undertake the technology assessment under Step Document References The primary references used in this document are: 1 EUROCONTROL/FAA Communications Operating Concept and Requirements (COCR) v1.0, March EUROCONTROL, Future Communications Infrastructure - Technology Investigations Step 1: Initial Technology Shortlist, QinetiQ, September EUROCONTROL, Future Communications Infrastructure - Technology Investigations. Evaluation Scenarios draft AENA - Framework for Spectrum Compatibility Analysis in L-Band for FCI technology Candidates version ICAO Annex 10 Volume V Aeronautical Radio Frequency Spectrum Utilisation 6 EUROCONTROL - Standard Inputs for EUROCONTROL Cost Benefit Analyses 2005 Edition Edition Number: 0.9 Draft Page 3

14 2. STEP 2 METHODOLOGY The aim of Step 2 is to conduct further, in-depth evaluation of the Step 1 short listed technologies. The Step-2 process will attempt to ascertain how and where each technology could be applied, and how they would perform in a typical operational environment. A more detailed assessment of performance and characteristics will be undertaken using to the maximum extent involvement of those people involved in developing candidate technologies. Parameters such as the number of base stations and the amount of channels/spectrum required to meet the COCR requirements (in terms of delivering the necessary capacity and QoS) will only become apparent when the technology is applied to a typical operational environment. To enable such evaluations to take place, a family of generic operational environments have been defined (referred to hereafter as scenarios) based on an extrapolation of real world ATC sectors and traffic loading from the SAAM tool which are expected to exist in the Phase 2 timeframe (~2025). The scenarios will allow simulation to take place to demonstrate the capacity and performance of each candidate technology. As a common set of scenarios will be used by all technologies (where appropriate), it will be possible to compare results and identify the technologies which are best suited to the various operational scenarios List of technologies to be assessed The results of the Step 1 analysis concluded with the following promising technologies as shown in Table 2-1. Page 4 Draft Edition Number: 0.9

15 Evolution of existing aeronautical systems or concepts: LDL AMACS Terrestrial systems: B-AMC WCDMA P34 Satellite systems INMARSAT SwiftBroadband Airport/surface systems e new satellite system(s) (commercial and/or custom ATS) Table 2-1 : Step 1: List of technologies for Step 2 assessment Each of these technologies will be described using a common template as shown in Appendix A, which will highlight their key features and description of how the technology has been tailored to meet ATM requirements. Wherever possible these templates will be populated by those developing candidate technologies. 2.2 Performance Requirements EUROCONTROL and the FAA have jointly developed the Communications Operating Concept and Requirements (COCR) for future Air-Ground communications infrastructure. The COCR specifies requirements for two time frames Phase 1 (up to 2020) where a mixture of voice and data communications will exist, and Phase 2 (beyond 2020) where data communications are expected to dominate. Within each Phase, communication requirements for ATS and AOC operations are determined for Air-Ground and Air-Air communications. The nature of communications is also split according to whether data is addressed or broadcast. There are therefore, 4 functional types of data communication to be considered: Air-Air (A/A) Addressed Air-Ground (A/G) Addressed Air-Air (A/A) Broadcast Air-Ground (A/G) Broadcast The Step 2 technology assessment will be against the COCR version 1.0 as the basis for defining requirements. Specifically it identifies capacity and quality of service requirements to meet ATS and AOC requirements for Phase 2 with and without the A-EXEC service. Edition Number: 0.9 Draft Page 5

16 The Performance Requirements are contained in a separate document which describes the Evaluation Scenarios Ref. 3. Page 6 Draft Edition Number: 0.9

17 3. TECHNOLOGY ASSESSMENT 3.1 Introduction The assessment process and its application are described in this section. In developing the assessment process and associated criteria the following points were considered The process had to be transparent and understandable It must have acceptance by Stakeholders the key (essential) criteria which candidate technologies must meet have been identified a set of desirable features against which the technologies can be ranked The assessment process applies the essential criteria to the selected technologies to identify those that meet the basic needs. In addition desirable features are evaluated in the detailed technology assessment phase and a ranking of the technologies is provided. A key input to the process is the ability of the technologies to meet the basic capacity requirements defined in the Evaluation Scenarios document Ref. 3. In developing the assessment process the evaluation scenarios and assessment criteria have been co-ordinated with the FAA/NASA task which is also assessing technology. The criteria have been reviewed by Stakeholders and their comments taken into account. 3.2 Assessment Categories As mentioned above there are two main categories used in the assessment, essential and desirable. Under each category there are a number of criteria. All the criteria under the essential category must be complied with before further detailed technical evaluation is undertaken to assess technologies against the desirable criteria. If a technology does not pass the essential criteria it is rejected. This is shown diagrammatically in Figure 3-1 below. ONE FOR EACH TECHNOLOGY PASS ESSENTIAL CRITERIA - spectrum compatibility - openness of stanards EVALUATION AGAINST DESIRABLE CRITERIA RANK TECHNOLOGIES FAIL REJECT TECHNOLOGY Edition Number: 0.9 Draft Page 7

18 Figure 3-1 Illustration of applying the criteria The set of desirable criteria has been chosen to identify the main requirements to be candidates for a future radio system. These are described in section 3.4 below. 3.3 ESSENTIAL CRITERIA Compatibility within the target band This criterion is used to determine if the proposed technology can co-exist with users currently operating or planned to be implemented in the target band. The target bands being considered in the FCS are VHF Band MHz (upper end of the VOR band) for airport, TMA and en-route communication L-Band 960 to 975 MHz MHz for airport, TMA and en-route communication C-Band MHz for airport surface communication Acceptance of this criterion will be against existing or planned ITU planning requirements using theoretical calculations, simulations or measurement see below. The conditions under which the technology is planned to utilise the target band must be stated. This should include assumptions of band usage such as whether the technology is designed to overlay the spectrum of existing users, does it assume the use of a dedicated part of the existing spectrum and what assumptions are made regarding the utilisation of the target band with current users. The follows interference effects should be considered - Co-site compatibility onboard the aircraft Air-to-Air compatibility Air-Ground compatibility Ground-to-Ground compatibility The type of emissions from the interferer to the victim receiver can be classified as follows: Out-of-Band Emissions. Out-of-band emissions are those on a frequency or frequencies immediately outside the necessary bandwidth which results from the modulation process, but excluding spurious emissions. Out-of-band emissions from a transmitter will cause an increase of background noise in the victim receiver pass band. The level of OOB emissions depends on the transmitted spectrum, the reception filter performance and the frequency separation between systems. The FRS non essential emissions attenuation are assumed to be in compliance with ITU- R Recommendation SM 329-9, i.e. a minimum of - 67 dbc Spurious Emissions. Spurious Emissions occur on a frequency or frequencies which are outside the necessary bandwidth and the level of which may be reduced without affecting the corresponding transmission of information. They include harmonic emissions, parasitic emissions, intermodulation products and frequency Page 8 Draft Edition Number: 0.9

19 conversion products but exclude out-of-band emissions. Spurious emissions begin at +/- 250 % of the system bandwidth from its centre frequency. Appendix 3 to the ITU Radio Regulations provides minimum attenuation requirements for spurious emissions for different types of services. Those minimum requirements may not be sufficient to protect other users. In this case, additional attenuation requirements have to be implemented. In-band Emissions. Some characteristics such as the temporal occupation of the transmitted signal (duty cycle) and the transmitted power will have an impact VHF Band ( MHz) Compatibility with VOR, Differential GPS transmissions and VHF AM(R)S systems must be shown. Requirements for compatibility with these systems are described in ICAO Annex 10 Volume 5 section L Band (960 to 1164 MHz) Compatibility with DME, SSR Mode S, and JTIDS systems must be shown. Guidance on applying this criterion for systems operating in this band is given in Ref. 4 Framework for Spectrum Compatibility Analysis in L-Band for FCI technology C Band ( MHz) Compatibility with MLS systems must be shown. Requirements for compatibility with these systems are described in ICAO Annex 10 Volume 5 section RF interference rejection/signal robustness. The FRS will have to exist in an environment where interference will come from existing users of the target band therefore the ability to handle a certain level of interference is vital. This will include own interference due to non-perfect frequency re-use, synchronisation, etc. Major aspects of interference rejection to be considered are Forward error corrector (FEC) mechanism; and Modulation scheme. Consideration of these topics and the design choices made in the candidate FRS must be provided as part of the system description and included in the proforma description shown in Appendix A section A2.7. The proforma provides discussion on these topics. Another technique that should be considered in reducing interference effects is that of transmitter power control. Consideration should be given to controlling the RF power to the minimum level to achieve the requirement performance. Consideration of this topic and the design choices made in the candidate FRS must be provided as part of the system description and included in the proforma description shown in Appendix A section A2.9. The proforma provides discussion on this topic. Edition Number: 0.9 Draft Page 9

20 Acceptance Acceptance will be based on demonstrating that agreed interference values such as desiredto-undesired signals levels could be achieved. It is recognised that a complete interference analysis is a very complex and a time consuming process and therefore it is unlikely to be completed within the timeframe of the FCS. However sufficient evidence must be provided to demonstrate compatibility at least theoretically but preferably through limited practical trials. If this criterion cannot be met then the technology is rejected Openness of the Standard This criterion is designed to determine if sufficient information is available on the technical standards on a fair and equitable basis. Availability of sufficient technical details is necessary to determine the characteristics of the technology and carry out some independent evaluation and validation if necessary. This information should be made available through an appropriate ICAO body. As a minimum, completion of the template shown in Appendix A to a reasonable level is required to pass this criterion. If standards exist but have a royalty payment associated with them or are subject to some form of limited usage, this could be acceptable. However has to be considered as an element of the implementation cost. If no standard currently exists then the system will be judged as passing provided that the entity progressing the system intends that the technical information will be made available in an open manner through an appropriate standardisation body including ICAO. The lack of standardisation activity could indicate lack of maturity of the technology, which will probably be reflected in the TRL level. It is also likely to increase the risk that the technology can be deployed within the relevant timeframe. If the technical standards are not open to aviation in any form then the technology is rejected. 3.4 DESIRABLE CRITERIA Desirable criteria are those for which a range of possible values can be determined in various configurations. No one technology will meet or exceed all the requirements therefore assigning values to these criteria will assist in comparing candidate technologies against each other in a common way. The importance of each desirable criterion is assigned in the ranking process as described in section 3.6 below. The set of desirable criteria is split into two main categories general and performance based. The two categories are briefly introduced below. Page 10 Draft Edition Number: 0.9

21 3.4.1 Generic Criteria The general criteria cover those attributes of potential technologies which are major discriminates in comparing one against the other. Other criteria have been considered but the following were chosen to be the most relevant Security Technology Readiness Level Flexibility Cost These criteria are described in more detail in section below Performance based Criteria Another set of key selection criteria is those associated with meeting the required capacity, integrity, availability and latency performance values. The performance values are defined in the Evaluation Scenarios document [Ref. 4] and have been determined for each of the following locations based on the requirements defined in the COCR [Ref. 1] namely: Airport Surface Airport Zone Terminal Manoeuvring Area En-Route Oceanic Remote and Polar For each of the locations, each technology will be evaluated as to its ability to meet the requirements. These criteria are described in more detail in section 3.5 below Generic Criteria Robustness of the RF signal It is assumed that the integrity and security of the message, on an end-to-end basis, is handled through authentication, integrity and encryption (if applied) features outside the FRS. Consequently this criterion is aimed at determining the robustness of the technology to interference of the RF signal. For the evaluation this is defined as the intentional manipulation of the S/N ratio of a victim radio in such a way that it is no longer operational. The COCR v1.0 (section 4.3.5) defines the following security requirements for services which have high severe, high catastrophic or medium availability requirements which covers most of the ATS and AOC services - Requirement Id R.FRS- SEC.1a Requirement The FRS shall provide a measure of resistance against deliberate insertion of RF interference when providing services with high severe or high catastrophic availability ranking. Associated FCI Requirements R.FCI-SEC.1 Edition Number: 0.9 Draft Page 11

22 Requirement Id R.FRS- SEC.1b Requirement The FRS should provide a measure of resistance against deliberate insertion of RF interference when providing services with medium availability ranking. Associated FCI Requirements R.FCI-SEC.1 The test for this criterion is dependent on the specific technology. A radio system using much more bandwidth than the bandwidth needed to transfer the information data rate is likely to be resistant to interference. This topic is discussed in further detail in section A2.8 in Appendix A. Criterion Jam resistant level 1 Robust to interference greater than 15dB 2 Not completely robust to interference greater than 5dB 3 Low tolerability to interference 5dB or less In assigning a value, evidence must be provided of any specific measures should be provided TRL The TRL value assigned under this criterion is based on the current level of development of the technology as a whole i.e. the target FRS as to be deployed in the target band supporting the designated services. The standard definition of TRL level as shown in Figure 3-2 is to be used. It should be noted that typically there is a relationship between the TRL and the length of time to deploy a technology. The lower the TRL value the less mature the technology, the longer the development phase and consequently there is a greater the risk in achievable deployment by a certain date. The timescale envisaged for this criterion is By this time the FRS must have reached a high level of maturity i.e. TRL level 9 and then be deployed by 2015 to allow a period of pre-operational use before entering operational service in The TRL will be assigned based on the information supplied by the proponent of the technology on tests and evaluations undertaken to date in the development of their system. Page 12 Draft Edition Number: 0.9

23 Figure 3-2 TRL stages For the technology evaluation the following grouping of TRL has been assigned. Criterion TRL number level 1 Technology is TRL 8 or 9 2 Technology is TRL 6 or 7 3 Technology is TRL 4 or 5 4 Technology is TRL 2 or 3 5 Technology is TRL 0 or Flexibility This general criterion is aimed at identifying options in the deployment of a technology which could enable a range of data rates/bandwidth to be chosen to meet the requirements in a particular service volume or to be tailored to a specific radio band. For example, the technology could offer a number of data rates, modulation options and channel bandwidths which can be chosen to meet the requirements. More options in the technology provide better flexibility to deploy the technology to meet local requirements or constraints. Edition Number: 0.9 Draft Page 13

24 Criterion Flexibility Value level 1 The technology can be deployed in several ways to provide a variety of performance values. 2 The technology can be deployed in only one way and provides fixed performance values Ground Infrastructure cost Note - Avionic costs are not considered as they are not a discriminator between technologies at this stage of development. An estimate of the avionics costs of each technology will be similar due to this immaturity. All avionics are expected to be implemented in similar ways e.g. a new unit which will be required with its own antenna. This criterion is used to indicate the typical cost to deploy the ground element of the FRS technology within a region (e.g. ECAC or NAS). The cost will be based on the number of radio units needed to achieve coverage in the proposed service volume of the target system. It is recognised that a single technology may not be designed to achieve entire coverage in all service volumes. In this case the technology assessment will aggregate the costs of a combination of technologies to achieve entire coverage in the region. For example a technology may be aimed at airport surface coverage only. This would need to be augmented by an air/ground service technology and therefore its cost would be added. In determining the cost, the number of ground stations is derived from the technology deployment plan for each system. This cost is compared to that of an equivalent service offered by a VHF data radio system. The comparison will be done based on a regional implementation i.e. in ECAC airspace. Criterion Cost Value level times less than the cost of VHF ground data radio system 2 10 times less than the cost of VHF ground data radio system 3 Similar cost to VHF ground data radio system 4 10 times the cost of VHF ground data radio system times the cost of VHF ground data radio system 3.5 Performance Based Criteria The performance of the candidate system will be evaluated against the requirements defined in the Evaluation Scenario document [Ref. 4] for each airspace location. Values used for this criterion range from 1 to 3. Value 1 means that the candidate technology as designed exceeds the requirements in the location for which it being assessed. A value 3 means that the technology does not meet the requirement in that particular location. A technology must meet requirements in one location from the following Airport Surface Page 14 Draft Edition Number: 0.9

25 Airport Zone Terminal Manoeuvring Area En-Route Oceanic Remote and Polar Criterion level Capacity Integrity Availability Latency 1 exceeds 1,2 or 3 1,2 or 3 1,2 or 3 1,2 or 3 requirement 2 = meets 1,2 or 3 1,2 or 3 1,2 or 3 1,2 or 3 requirement 3 = does not meet requirement 1,2 or 3 1,2 or 3 1,2 or 3 1,2 or 3 It is important to note the significance of the quantified and validated assessment criteria where the performance requirement is an absolute, quantifiable value. Quantified means that the technology has specified a value that it can meet whereby validated will mean that this quantified figure has been demonstrated by simulation or experimentation. Taking integrity as an example, the system may be designed to exceed the COCR requirement and hence this would result in a good assessment level score for the quantified category, but without some sort of demonstration, the validated score would remain low. 3.6 Ranking In the above section, a set of criteria has been defined against which technologies will be assessed in terms of key attributes. In order to rank technologies in terms of their suitability to meet requirements, a pro-forma/template has been designed to capture criteria information Classes As a result of the information supplied in the criteria, technologies will be grouped into one of 4 classes for each type of airspace. The classes represent a measure of the suitability of the technologies to meet the requirement in that environment; the lower the number the more of the requirements can be met. Class 1 Proven, viable, standardised technology, available for operational use. Class 2 - Technology has potential to meet many requirements. Class 3 - Technology has potential to meet some requirements. Class 4 - Technology has potential to few requirements. Note - It is recognised that a technology that is ranked as Class 1 will not be identified as this means it meets the requirements to be the FRS. This Class 1 is included to show the complete set of classes. Edition Number: 0.9 Draft Page 15

26 3.6.2 Masks For each Class a mask is applied which determines which criteria level is considered. The masks for each Class are shown as the shaded cells in the tables below. The shading depicts the criteria values that are of interest in assigning the class to a technology. Only if the technology has an assessment score in all of the categories will it be categorised as Class 1. In the above example, regardless of the assessment score in all other categories, a system that is not assessed as Level 1 for cost will not qualify as Class 1. The key thing to note is that Class 2 is wider and permits more variance between assessed levels for each category. The same approach has been extended to define Class 3 and Class Class 1 Mask Criterion Value Security TRL Flexibility Cost Capacity Integrity Availability Latency Class 2 Mask Criterion Value Security TRL Flexibility Cost Capacity Integrity Availability Latency Class 3 Mask Criterion Value Security TRL Flexibility Cost Capacity Integrity Availability Latency Page 16 Draft Edition Number: 0.9

27 3.6.6 Class 4 Mask Criterion Value Security TRL Flexibility Cost Capacity Integrity Availability Latency Comparison of technologies The candidate technologies will be ranked based on the number of cells compared against each mask. This will result in an allocation of technologies to a class. Edition Number: 0.9 Draft Page 17

28 4. CONCLUSIONS This document defines the methodology to evaluate candidate technologies to meet the requirements of the FRS. This is based on two main types of criteria essential and desirable. Essential criteria are spectrum compatibility and openness of standards. If these criteria are not passed then the technology will be rejected. The desirable criteria are used to help rank the technologies in terms of their suitability to meet requirements in the required locations. Included in this category are performance requirements i.e. capacity, continuity, availability, integrity and latency. Other desirable criteria cover those attributes of potential technologies which are major discriminates in comparing one against the other. Other criteria have been considered but the following were chosen to be the most relevant Security Technology Readiness Level Flexibility Cost Having identified a set of criteria, the technologies are evaluated against them and a ranking scheme is applied to each technology. The ranking will result in a number of technologies in each class. This will be used to assist in the selection of the most compliant technology as the FRS. Page 18 Draft Edition Number: 0.9

29 TECHNOLOGY X A1 OVERVIEW OF TECHNOLOGY APPENDIX A This section should give a general overview of the technology as it currently stands detailing its functionality etc. A.1.1 Overview Give brief description of technology and its capabilities. Specific details can be given in later sections. A 1.2 Functional Architecture Detail functions and their sub-functions and interfaces (internal and external) that define the execution sequencing, conditions for control or data flow. A 1.3 Services Provided & Key Features List of technology main features and the types of services it can provide. A1.4 Air Interface Description: PHY, MAC & Network A description of the operating system needs to be given here that will provide specifics of the radio transmission between base station and mobile unit. Details of system layers and how they are interconnected should follow. A1.5 Standards Provide information on the standards for technology detailing and their maturity. 1.6 Technology Readiness Level (TRL) Give details of TRL to describe the technology s maturity level. Edition Number: 0.9 Draft Page 19

30 A2 APPLICATION OF TECHNOLOGY TO ATM This section should deal with the actual applicability of the technology and its performance capabilities to provide aeronautical communications. A2.1 Concept of Operation A general overview should be provided here detailing technology ability to operate in the ATM environment. Adaptations required to support ATM use should be noted within this section detailing specific changes that need to be made to the technology. A2.2 Spectrum Considerations There are three specific points that need to be addressed: i) Target band which band is the system proposing to operate within i.e. VHF, C- band or L-band. ii) Basic channel bandwidth what bandwidth is proposed for the technology iii) Compatibility with existing users within the band already A2.3 Airspace Application Describe what airspace the technology will work within i.e. APT, TMA, ENR, or ORP (oceanic, remote and polar). A2.4 ATM services supported Which of the following services can the technology support: A/G Addressed, A/G Broadcast, A/A Addressed, A/A Broadcast Also detail the technology services that will support the ATM services listed above. A2.5 Proposed Architecture for Technology System Description of functional architecture mapped to physical system architecture detailing the proposed ground infrastructure. Items that need to be considered here are the number of base stations necessary, size of cells for the configuration of the system, potential link budget and the maximum range of the technology. Note: this system should have the ability to meet the traffic scenarios generated earlier in this document. A2.6 Performance Assurance This section should detail the quality of service of technology ensuring it has required capacity. (i.e. ensuring that it can meet the capacity requirements with the domain of operation as generated in the traffic scenarios.) Also it should provide some evidence, preferably through simulation or alternatively theoretical calculations showing derivation of integrity, continuity, availability, priority of messages and integrity. Page 20 Draft Edition Number: 0.9

31 Information on how performance is maintained under high Doppler shift conditions should be described. Doppler shift compensation is particularly critical for those systems supporting air/air communication which could encounter speeds of at least 2000km/h relative speed or higher if military aircraft are considered. A2.7 RF interference rejection / signal robustness. The FRS can expect interference coming from existing users of the target band (for example, for systems operating in the L band systems this includes JTIDS- DME,UAT,SSR, UAT). Therefore adequate measures to handle a certain level of interference are vital to ensure effective performance of the system. This will include a certain amount of FRS own interference due to non-perfect frequency re-use, synchronisation. This section should describe the measures taken to achieve interference rejection the main ones being: Forward error corrector (FEC) mechanism and the chosen modulation scheme. Notes on these topics are below FEC : The description should provide a clear indication/description and rough evaluation of the forward error mechanism used (FEC). Generally 2 FEC types are in use: block (such as Reed Salomon) and convolutional memory oriented (such as Viterbi) encoders, the first being far less efficient compared to the last one. Block encoder decision criteria are only based on the actual block under evaluation while memory-oriented encoders are benefiting from previously sent frames. Convolutional FEC should score higher compared to block encoders as the more overhead the more errors can be corrected ( =the higher interference is overcome). E.g. VDL2 RS ( 255,249) has only a 255/249 = 2,4% overhead and is not able to make deep corrections. WiMax uses in one of its configurations RS(24,16), has a 24/16 = 50% overhead, and is to be considered far more powerful than VDL2 FEC. Note: all this goes at the expense of bandwidth consumption.(this aspect should be handled as well but not under robustness). The same evaluation can be done for memory oriented FEC such as Viterbi. Besides being far more effective than block error FEC overhead is easily to find out. WiMax, 3GPP, CDMA2000, INMARSAT uses Viterbi such as Viterbi(1/2) : meaning that there is a 2/1=100% overhead. Others commonly used are Viterbi (1/3) Viterbi (1/4) each of them better than previous ones but also more overhead (=BW) involved. Best FEC is Turbo as they use 2 concatenated VITERBI with intermediate interleaver. As they reach the near Shannon bit error corrector threshold (around 1dB of limit) no technology today can do better. Turbos are characterised the same way Viterbi are: so Turbo (1/2) means also a 100% overhead. Note :Turbo goes often at the expense of processing power and not of BW (compared against Viterbi). MODULATION SCHEME : Robustness is also directly linked to modulation scheme as the higher the modulation order (= amount of bits sent within one symbol) the less robust the system becomes (this higher interference increased the bit error rate(ber). Therefore in order of Robustness the following rule should be taken : (high to low) : BPSK, QPSK, 16QPSK, 16QAM, 32QAM, 64QAM, 256QAM). In fact the more states a modulation scheme has the less robust it. Note the inverse impact on bandwidth utilisation: The higher the modulation rate the less spectrum will be needed. Once again BW demands have to be evaluated separately but not under robustness itself. It is not likely that the higher order modulation schemes such as 256 QAM will ever be Edition Number: 0.9 Draft Page 21

32 used in aviation with the exception of maybe A/C being docked at the gates. Consideration should be given to controlling the RF power to the minimum level to achieve the requirement performance. For example, it may be possible to reduce the transmitter power level when the aircraft is on the surface of an airport (triggered by contact on wheels) in order to protect adjacent channels with minimal separation distance of, say, 2 gates. A description of the power control mechanism, if any, should be described in this section. For information the following technologies have power control capability as described below - UMTS (3GPP) provides power control over a wide range, namely 80 db and with a power control update rate of 1500 HZ when operating in closed loop. (all specified for uplink). Power control for downlink is 20 db. CDMA 2000 (3GPP2) is providing a similar power control range but with an update rate of 800Hz only (reverse link). Forward link is 20 db as well. WiMax e (actually based on ) which has power control mechanism of up to 40 db. As this is proposed as an airport technology power control is important, as aircraft separation is minimal on the ground. However air/ground and reliable air/air communication will benefit from power control. VDLMode 2 power is halved when the aircraft is on the ground however the major interference is caused by aircraft flying at high flight levels. Current CNS technologies always emit full power apart from VDLM2. For example, at VHF the DOC area is based on the sector size to be supported which is roughly only 5% of the total protection area for that particular frequency channel (criteria = radio horizon). Therefore there is limited frequency re-use and spectrum cannot be used efficiently. Frequency re-use is related to the overall capacity of the FRS and determines spectrum usage flexibility. In the case of a/a communication power control may be even more important to support the several different operational range classes for dedicated services. If all aircraft emit at maximum power (corresponding to 200nmi range) there could be serious interference problems and capacity limitations. In addition, as the propagation delay times are quite different for a 20 NM range compared to a 200 NM range this will lead either to a reduction of time slots (capacity goes down) or to an increase of interference (BER goes up). Those technologies proposing the use of a flexible modulation scheme (BPSK, QPSK,16-64QAM) will need power control as well (see WiMax). ). Note - due to the line of sight path loss, signals are not attenuated with an order of 4 to 5 as for ground-based systems but decrease only with an order of 2. Another issue is that, though voice is not FCS main target, there may be little difference in the quality between voice arriving with a BER or with BER This indicates that there is not always a need for perfect link budget conditions hence justifying power emissions limitations. Power control could be handled in closed loop for air/ground addressed communication but also for air/air broadcasting could provide some kind of power control even in open loop by e.g. setting a certain fixed power level depending on the air/air range as defined by COCR. A2.8 Security of the RF signal Security of the RF signal should also be considered and design choices described. The amount of interference resistance (in dbs) should be determined. It should be noted that the bandwidth of a system has a direct relationship to its interference resistance value (in db) 10 x log (used BW / information data rate needed) - also called spreading gain. Page 22 Draft Edition Number: 0.9