< draft-ietf-raw-ldacs-04.txt   draft-ietf-raw-ldacs-05.txt >
RAW N. Maeurer, Ed. RAW N. Maeurer, Ed.
Internet-Draft T. Graeupl, Ed. Internet-Draft T. Graeupl, Ed.
Intended status: Informational German Aerospace Center (DLR) Intended status: Informational German Aerospace Center (DLR)
Expires: 2 May 2021 C. Schmitt, Ed. Expires: 5 May 2021 C. Schmitt, Ed.
Research Institute CODE, UniBwM Research Institute CODE, UniBwM
29 October 2020 1 November 2020
L-band Digital Aeronautical Communications System (LDACS) L-band Digital Aeronautical Communications System (LDACS)
draft-ietf-raw-ldacs-04 draft-ietf-raw-ldacs-05
Abstract Abstract
This document provides an overview of the architecture of the L-band This document provides an overview of the architecture of the L-band
Digital Aeronautical Communications System (LDACS), which provides a Digital Aeronautical Communications System (LDACS), which provides a
secure, scalable and spectrum efficient terrestrial data link for secure, scalable and spectrum efficient terrestrial data link for
civil aviation. LDACS is a scheduled, reliable multi-application civil aviation. LDACS is a scheduled, reliable multi-application
cellular broadband system with support for IPv6. LDACS shall provide cellular broadband system with support for IPv6. LDACS SHALL provide
a data link for IP network-based aircraft guidance. High reliability a data link for IP network-based aircraft guidance. High reliability
and availability for IP connectivity over LDACS are therefore and availability for IP connectivity over LDACS are therefore
essential. essential.
Status of This Memo Status of This Memo
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provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on 2 May 2021. This Internet-Draft will expire on 5 May 2021.
Copyright Notice Copyright Notice
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Motivation and Use Cases . . . . . . . . . . . . . . . . . . 5 3. Motivation and Use Cases . . . . . . . . . . . . . . . . . . 5
3.1. Voice Communications Today . . . . . . . . . . . . . . . 5 3.1. Voice Communications Today . . . . . . . . . . . . . . . 5
3.2. Data Communications Today . . . . . . . . . . . . . . . . 6 3.2. Data Communications Today . . . . . . . . . . . . . . . . 6
4. Provenance and Documents . . . . . . . . . . . . . . . . . . 7 4. Provenance and Documents . . . . . . . . . . . . . . . . . . 7
5. Applicability . . . . . . . . . . . . . . . . . . . . . . . . 8 5. Applicability . . . . . . . . . . . . . . . . . . . . . . . . 8
5.1. Advances Beyond the State-of-the-Art . . . . . . . . . . 8 5.1. Advances Beyond the State-of-the-Art . . . . . . . . . . 8
5.1.1. Priorities . . . . . . . . . . . . . . . . . . . . . 8 5.1.1. Priorities . . . . . . . . . . . . . . . . . . . . . 8
5.1.2. Security . . . . . . . . . . . . . . . . . . . . . . 8 5.1.2. Security . . . . . . . . . . . . . . . . . . . . . . 8
5.1.3. High Data Rates . . . . . . . . . . . . . . . . . . . 9 5.1.3. High Data Rates . . . . . . . . . . . . . . . . . . . 9
5.2. Application . . . . . . . . . . . . . . . . . . . . . . . 9 5.2. Application . . . . . . . . . . . . . . . . . . . . . . . 9
skipping to change at page 3, line 30 skipping to change at page 3, line 31
One of the main pillars of the modern Air Traffic Management (ATM) One of the main pillars of the modern Air Traffic Management (ATM)
system is the existence of a communication infrastructure that system is the existence of a communication infrastructure that
enables efficient aircraft control and safe separation in all phases enables efficient aircraft control and safe separation in all phases
of flight. Current systems are technically mature but suffering from of flight. Current systems are technically mature but suffering from
the VHF band's increasing saturation in high-density areas and the the VHF band's increasing saturation in high-density areas and the
limitations posed by analogue radio communications. Therefore, limitations posed by analogue radio communications. Therefore,
aviation globally and the European Union (EU) in particular, strives aviation globally and the European Union (EU) in particular, strives
for a sustainable modernization of the aeronautical communication for a sustainable modernization of the aeronautical communication
infrastructure. infrastructure.
In the long-term, ATM communication shall transition from analogue In the long-term, ATM communication SHALL transition from analogue
VHF voice and VDLM2 communication to more spectrum efficient digital VHF voice and VDLM2 communication to more spectrum efficient digital
data communication. The European ATM Master Plan foresees this data communication. The European ATM Master Plan foresees this
transition to be realized for terrestrial communications by the transition to be realized for terrestrial communications by the
development (and potential implementation) of the L-band Digital development (and potential implementation) of the L-band Digital
Aeronautical Communications System (LDACS). LDACS shall enable IPv6 Aeronautical Communications System (LDACS). LDACS SHALL enable IPv6
based air- ground communication related to the aviation safety and based air- ground communication related to the aviation safety and
regularity of flight. The particular challenge is that no additional regularity of flight. The particular challenge is that no additional
spectrum can be made available for terrestrial aeronautical spectrum can be made available for terrestrial aeronautical
communication. It was thus necessary to develop co-existence communication. It was thus necessary to develop co-existence
mechanism/procedures to enable the interference free operation of mechanism/procedures to enable the interference free operation of
LDACS in parallel with other aeronautical services/systems in the LDACS in parallel with other aeronautical services/systems in the
same frequency band. same frequency band.
Since LDACS shall be used for aircraft guidance, high reliability and Since LDACS SHALL be used for aircraft guidance, high reliability and
availability for IP connectivity over LDACS are essential. availability for IP connectivity over LDACS are essential.
1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
2. Terminology 2. Terminology
The following terms are used in the context of RAW in this document: The following terms are used in the context of RAW in this document:
A2A Air-to-Air A2A Air-to-Air
AeroMACS Aeronautical Mobile Airport Communication System AeroMACS Aeronautical Mobile Airport Communication System
A2G Air-to-Ground A2G Air-to-Ground
ACARS Aircraft Communications Addressing and Reporting System ACARS Aircraft Communications Addressing and Reporting System
ADS-C Automatic Dependent Surveillance - Contract ADS-C Automatic Dependent Surveillance - Contract
AM(R)S Aeronautical Mobile (Route) Service AM(R)S Aeronautical Mobile (Route) Service
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VHF Very High Frequency VHF Very High Frequency
VI Voice Interface VI Voice Interface
3. Motivation and Use Cases 3. Motivation and Use Cases
Aircraft are currently connected to Air-Traffic Control (ATC) and Aircraft are currently connected to Air-Traffic Control (ATC) and
Aeronautical Operational Control (AOC) via voice and data Aeronautical Operational Control (AOC) via voice and data
communications systems through all phases of a flight. Within the communications systems through all phases of a flight. Within the
airport terminal, connectivity is focused on high bandwidth airport terminal, connectivity is focused on high bandwidth
communications, while during en-route high reliability, robustness, communications, while during en-route high reliability, robustness,
and range is the main focus. Voice communications may use the same and range is the main focus. Voice communications MAY use the same
or different equipment as data communications systems. In the or different equipment as data communications systems. In the
following the main differences between voice and data communications following the main differences between voice and data communications
capabilities are summarized. The assumed use cases for LDACS capabilities are summarized. The assumed use cases for LDACS
completes the list of use cases stated in [RAW-USE-CASES] and the completes the list of use cases stated in [RAW-USE-CASES] and the
list of reliable and available wireless technologies presented in list of reliable and available wireless technologies presented in
[RAW-TECHNOS]. [RAW-TECHNOS].
3.1. Voice Communications Today 3.1. Voice Communications Today
Voice links are used for Air-to-Ground (A2G) and Air-to-Air (A2A) Voice links are used for Air-to-Ground (A2G) and Air-to-Air (A2A)
communications. The communication equipment is either ground-based communications. The communication equipment is either ground-based
working in the High Frequency (HF) or Very High Frequency (VHF) working in the High Frequency (HF) or Very High Frequency (VHF)
frequency band or satellite-based. All VHF and HF voice frequency band or satellite-based. All VHF and HF voice
communications is operated via open broadcast channels without communications is operated via open broadcast channels without
authentication, encryption or other protective measures. The use of authentication, encryption or other protective measures. The use of
well-proven communication procedures via broadcast channels helps to well-proven communication procedures via broadcast channels helps to
enhance the safety of communications by taking into account that enhance the safety of communications by taking into account that
other users may encounter communication problems and may be other users MAY encounter communication problems and MAY be
supported, if required. The main voice communications media is still supported, if REQUIRED. The main voice communications media is still
the analogue VHF Double Side-Band Amplitude Modulation (DSB-AM) the analogue VHF Double Side-Band Amplitude Modulation (DSB-AM)
communications technique, supplemented by HF Single Side-Band communications technique, supplemented by HF Single Side-Band
Amplitude Modulation and satellite communications for remote and Amplitude Modulation and satellite communications for remote and
oceanic areas. DSB-AM has been in use since 1948, works reliably and oceanic areas. DSB-AM has been in use since 1948, works reliably and
safely, and uses low-cost communication equipment. These are the safely, and uses low-cost communication equipment. These are the
main reasons why VHF DSB-AM communications is still in use, and it is main reasons why VHF DSB-AM communications is still in use, and it is
likely that this technology will remain in service for many more likely that this technology will remain in service for many more
years. This however results in current operational limitations and years. This however results in current operational limitations and
impediments in deploying new Air-Traffic Management (ATM) impediments in deploying new Air-Traffic Management (ATM)
applications, such as flight-centric operation with Point-to-Point applications, such as flight-centric operation with Point-to-Point
skipping to change at page 6, line 18 skipping to change at page 6, line 23
provided by ground-based equipment operating either on HF or VHF provided by ground-based equipment operating either on HF or VHF
radio bands or by legacy satellite systems. All these communication radio bands or by legacy satellite systems. All these communication
systems are using narrowband radio channels with a data throughput systems are using narrowband radio channels with a data throughput
capacity in order of kilobits per second. While the aircraft is on capacity in order of kilobits per second. While the aircraft is on
ground some additional communications systems are available, like the ground some additional communications systems are available, like the
Aeronautical Mobile Airport Communication System (AeroMACS) or public Aeronautical Mobile Airport Communication System (AeroMACS) or public
cellular networks, operating in the Airport (APT) domain and able to cellular networks, operating in the Airport (APT) domain and able to
deliver broadband communication capability. deliver broadband communication capability.
The data communication networks used for the transmission of data The data communication networks used for the transmission of data
relating to the safety and regularity of the flight must be strictly relating to the safety and regularity of the flight MUST be strictly
isolated from those providing entertainment services to passengers. isolated from those providing entertainment services to passengers.
This leads to a situation that the flight crews are supported by This leads to a situation that the flight crews are supported by
narrowband services during flight while passengers have access to narrowband services during flight while passengers have access to
inflight broadband services. The current HF and VHF data links inflight broadband services. The current HF and VHF data links
cannot provide broadband services now or in the future, due to the cannot provide broadband services now or in the future, due to the
lack of available spectrum. This technical shortcoming is becoming a lack of available spectrum. This technical shortcoming is becoming a
limitation to enhanced ATM operations, such as Trajectory-Based limitation to enhanced ATM operations, such as Trajectory-Based
Operations and 4D trajectory negotiations. Operations and 4D trajectory negotiations.
Satellite-based communications are currently under investigation and Satellite-based communications are currently under investigation and
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LDACS in the open. LDACS in the open.
Up to now LDACS standardization has been focused on the development Up to now LDACS standardization has been focused on the development
of the physical layer and the data link layer, only recently have of the physical layer and the data link layer, only recently have
higher layers come into the focus of the LDACS development higher layers come into the focus of the LDACS development
activities. There is currently no "IPv6 over LDACS" specification activities. There is currently no "IPv6 over LDACS" specification
publicly available; however, SESAR2020 has started the testing of publicly available; however, SESAR2020 has started the testing of
IPv6-based LDACS testbeds. IPv6-based LDACS testbeds.
The IPv6 architecture for the aeronautical telecommunication network The IPv6 architecture for the aeronautical telecommunication network
is called the Future Communications Infrastructure (FCI). FCI shall is called the Future Communications Infrastructure (FCI). FCI SHALL
support quality of service, diversity, and mobility under the support quality of service, diversity, and mobility under the
umbrella of the "multi-link concept". This work is conducted by ICAO umbrella of the "multi-link concept". This work is conducted by ICAO
Communication Panel working group WG-I. Communication Panel working group WG-I.
In addition to standardization activities several industrial LDACS In addition to standardization activities several industrial LDACS
prototypes have been built. One set of LDACS prototypes has been prototypes have been built. One set of LDACS prototypes has been
evaluated in flight trials confirming the theoretical results evaluated in flight trials confirming the theoretical results
predicting the system performance [GRA2018] [SCH20191]. predicting the system performance [GRA2018] [SCH20191].
5. Applicability 5. Applicability
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LDACS is a multi-application cellular broadband system capable of LDACS is a multi-application cellular broadband system capable of
simultaneously providing various kinds of Air Traffic Services simultaneously providing various kinds of Air Traffic Services
(including ATS-B3) and AOC communications services from deployed (including ATS-B3) and AOC communications services from deployed
Ground-Stations (GS). The LDACS A2G sub-system physical layer and Ground-Stations (GS). The LDACS A2G sub-system physical layer and
data link layer are optimized for data link communications, but the data link layer are optimized for data link communications, but the
system also supports digital air-ground voice communications. system also supports digital air-ground voice communications.
LDACS supports communication in all airspaces (airport, terminal LDACS supports communication in all airspaces (airport, terminal
maneuvering area, and en-route), and on the airport surface. The maneuvering area, and en-route), and on the airport surface. The
physical LDACS cell coverage is effectively de-coupled from the physical LDACS cell coverage is effectively de-coupled from the
operational coverage required for a particular service. This is new operational coverage REQUIRED for a particular service. This is new
in aeronautical communications. Services requiring wide-area in aeronautical communications. Services requiring wide-area
coverage can be installed at several adjacent LDACS cells. The coverage can be installed at several adjacent LDACS cells. The
handover between the involved LDACS cells is seamless, automatic, and handover between the involved LDACS cells is seamless, automatic, and
transparent to the user. Therefore, the LDACS A2G communications transparent to the user. Therefore, the LDACS A2G communications
concept enables the aeronautical communication infrastructure to concept enables the aeronautical communication infrastructure to
support future dynamic airspace management concepts. support future dynamic airspace management concepts.
5.1. Advances Beyond the State-of-the-Art 5.1. Advances Beyond the State-of-the-Art
LDACS offers several capabilities that are not provided in LDACS offers several capabilities that are not provided in
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The user data rate of LDACS is 315 kbit/s to 1428 kbit/s on the The user data rate of LDACS is 315 kbit/s to 1428 kbit/s on the
forward link (FL) for the connection Ground-to-Air (G2A), and 294 forward link (FL) for the connection Ground-to-Air (G2A), and 294
kbit/s to 1390 kbit/s on the reverse link (RF) for the connection kbit/s to 1390 kbit/s on the reverse link (RF) for the connection
A2G, depending on coding and modulation. This is 50 times the amount A2G, depending on coding and modulation. This is 50 times the amount
terrestrial digital aeronautical communications systems such as VDLM2 terrestrial digital aeronautical communications systems such as VDLM2
provide [SCH20191]. provide [SCH20191].
5.2. Application 5.2. Application
LDACS shall be used by several aeronautical applications ranging from LDACS SHALL be used by several aeronautical applications ranging from
enhanced communication protocol stacks (multi-homed mobile IPv6 enhanced communication protocol stacks (multi-homed mobile IPv6
networks in the aircraft and potentially ad-hoc networks between networks in the aircraft and potentially ad-hoc networks between
aircraft) to classical communication applications (sending GBAS aircraft) to classical communication applications (sending GBAS
correction data) and integration with other service domains (using correction data) and integration with other service domains (using
the communication signal for navigation). the communication signal for navigation).
5.2.1. Air-to-Ground Multilink 5.2.1. Air-to-Ground Multilink
It is expected that LDACS together with upgraded satellite-based It is expected that LDACS together with upgraded satellite-based
communications systems will be deployed within the FCI and constitute communications systems will be deployed within the FCI and constitute
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Both technologies, LDACS and satellite systems, have their specific Both technologies, LDACS and satellite systems, have their specific
benefits and technical capabilities which complement each other. benefits and technical capabilities which complement each other.
Especially, satellite systems are well-suited for large coverage Especially, satellite systems are well-suited for large coverage
areas with less dense air traffic, e.g. oceanic regions. LDACS is areas with less dense air traffic, e.g. oceanic regions. LDACS is
well-suited for dense air traffic areas, e.g. continental areas or well-suited for dense air traffic areas, e.g. continental areas or
hot-spots around airports and terminal airspace. In addition, both hot-spots around airports and terminal airspace. In addition, both
technologies offer comparable data link capacity and, thus, are well- technologies offer comparable data link capacity and, thus, are well-
suited for redundancy, mutual back-up, or load balancing. suited for redundancy, mutual back-up, or load balancing.
Technically the FCI multilink concept shall be realized by multi- Technically the FCI multilink concept SHALL be realized by multi-
homed mobile IPv6 networks in the aircraft. The related protocol homed mobile IPv6 networks in the aircraft. The related protocol
stack is currently under development by ICAO and the Single European stack is currently under development by ICAO and the Single European
Sky ATM Research framework. Sky ATM Research framework.
5.2.2. Air-to-Air Extension for LDACS 5.2.2. Air-to-Air Extension for LDACS
A potential extension of the multi-link concept is its extension to A potential extension of the multi-link concept is its extension to
ad-hoc networks between aircraft. ad-hoc networks between aircraft.
Direct A2A communication between aircrafts in terms of ad-hoc data Direct A2A communication between aircrafts in terms of ad-hoc data
networks is currently considered a research topic since there is no networks is currently considered a research topic since there is no
immediate operational need for it, although several possible use immediate operational need for it, although several possible use
cases are discussed (digital voice, wake vortex warnings, and cases are discussed (digital voice, wake vortex warnings, and
trajectory negotiation) [BEL2019]. It should also be noted that trajectory negotiation) [BEL2019]. It SHOULD also be noted that
currently deployed analog VHF voice radios support direct voice currently deployed analog VHF voice radios support direct voice
communication between aircraft, making a similar use case for digital communication between aircraft, making a similar use case for digital
voice plausible. voice plausible.
LDACS direct A2A is currently not part of standardization. LDACS direct A2A is currently not part of standardization.
5.2.3. Flight Guidance 5.2.3. Flight Guidance
The FCI (and therefore LDACS) shall be used to host flight guidance. The FCI (and therefore LDACS) SHALL be used to host flight guidance.
This is realized using three applications: This is realized using three applications:
1. Context Management (CM): The CM application shall manage the 1. Context Management (CM): The CM application SHALL manage the
automatic logical connection to the ATC center currently automatic logical connection to the ATC center currently
responsible to guide the aircraft. Currently this is done by the responsible to guide the aircraft. Currently this is done by the
air crew manually changing VHF voice frequencies according to the air crew manually changing VHF voice frequencies according to the
progress of the flight. The CM application automatically sets up progress of the flight. The CM application automatically sets up
equivalent sessions. equivalent sessions.
2. Controller Pilot Data Link Communication (CPDLC): The CPDLC 2. Controller Pilot Data Link Communication (CPDLC): The CPDLC
application provides the air crew with the ability to exchange application provides the air crew with the ability to exchange
data messages similar to text messages with the currently data messages similar to text messages with the currently
responsible ATC center. The CPDLC application shall take over responsible ATC center. The CPDLC application SHALL take over
most of the communication currently performed over VHF voice and most of the communication currently performed over VHF voice and
enable new services that do not lend themselves to voice enable new services that do not lend themselves to voice
communication (e.g., trajectory negotiation). communication (e.g., trajectory negotiation).
3. Automatic Dependent Surveillance - Contract (ADS-C): ADS-C 3. Automatic Dependent Surveillance - Contract (ADS-C): ADS-C
reports the position of the aircraft to the currently active ATC reports the position of the aircraft to the currently active ATC
center. Reporting is bound to "contracts", i.e. pre-defined center. Reporting is bound to "contracts", i.e. pre-defined
events related to the progress of the flight (i.e. the events related to the progress of the flight (i.e. the
trajectory). ADS-C and CPDLC are the primary applications used to trajectory). ADS-C and CPDLC are the primary applications used to
implement in-flight trajectory management. implement in-flight trajectory management.
CM, CPDLC, and ADS-C are available on legacy datalinks, but not CM, CPDLC, and ADS-C are available on legacy datalinks, but not
widely deployed and with limited functionality. widely deployed and with limited functionality.
Further ATC applications may be ported to use the FCI or LDACS as Further ATC applications MAY be ported to use the FCI or LDACS as
well. A notable application is GBAS for secure, automated landings: well. A notable application is GBAS for secure, automated landings:
The Global Navigation Satellite System (GNSS) based Ground Based The Global Navigation Satellite System (GNSS) based Ground Based
Augmentation System (GBAS) is used to improve the accuracy of GNSS to Augmentation System (GBAS) is used to improve the accuracy of GNSS to
allow GNSS based instrument landings. This is realized by sending allow GNSS based instrument landings. This is realized by sending
GNSS correction data (e.g., compensating ionospheric errors in the GNSS correction data (e.g., compensating ionospheric errors in the
GNSS signal) to the aircraft's GNSS receiver via a separate data GNSS signal) to the aircraft's GNSS receiver via a separate data
link. Currently the VDB data link is used. VDB is a narrow-band link. Currently the VDB data link is used. VDB is a narrow-band
single-purpose datalink without advanced security only used to single-purpose datalink without advanced security only used to
transmit GBAS correction data. This makes VDB a natural candidate transmit GBAS correction data. This makes VDB a natural candidate
for replacement by LDACS. for replacement by LDACS.
5.2.4. Business Communication of Airlines 5.2.4. Business Communication of Airlines
In addition to air traffic services AOC services shall be transmitted In addition to air traffic services AOC services SHALL be transmitted
over LDACS. AOC is a generic term referring to the business over LDACS. AOC is a generic term referring to the business
communication of airlines. Regulatory this is considered related to communication of airlines. Regulatory this is considered related to
the safety and regularity of flight and may therefore be transmitted the safety and regularity of flight and MAY therefore be transmitted
over LDACS. over LDACS.
AOC communication is considered the main business case for LDACS AOC communication is considered the main business case for LDACS
communication service providers since modern aircraft generate communication service providers since modern aircraft generate
significant amounts of data (e.g., engine maintenance data). significant amounts of data (e.g., engine maintenance data).
5.2.5. LDACS Navigation 5.2.5. LDACS Navigation
Beyond communication radio signals can always also be used for Beyond communication radio signals can always also be used for
navigation. LDACS takes this into account. navigation. LDACS takes this into account.
For future aeronautical navigation, ICAO recommends the further For future aeronautical navigation, ICAO recommends the further
development of GNSS based technologies as primary means for development of GNSS based technologies as primary means for
navigation. However, the drawback of GNSS is its inherent single navigation. However, the drawback of GNSS is its inherent single
point of failure - the satellite. Due to the large separation point of failure - the satellite. Due to the large separation
between navigational satellites and aircraft, the received power of between navigational satellites and aircraft, the received power of
GNSS signals on the ground is very low. As a result, GNSS GNSS signals on the ground is very low. As a result, GNSS
disruptions might occasionally occur due to unintentional disruptions might occasionally occur due to unintentional
interference, or intentional jamming. Yet the navigation services interference, or intentional jamming. Yet the navigation services
must be available with sufficient performance for all phases of MUST be available with sufficient performance for all phases of
flight. Therefore, during GNSS outages, or blockages, an alternative flight. Therefore, during GNSS outages, or blockages, an alternative
solution is needed. This is commonly referred to as Alternative solution is needed. This is commonly referred to as Alternative
Positioning, Navigation, and Timing (APNT). Positioning, Navigation, and Timing (APNT).
One of such APNT solution consists of integrating the navigation One of such APNT solution consists of integrating the navigation
functionality into LDACS. The ground infrastructure for APNT is functionality into LDACS. The ground infrastructure for APNT is
deployed through the implementation of LDACS's GSs and the navigation deployed through the implementation of LDACS's GSs and the navigation
capability comes "for free". capability comes "for free".
LDACS navigation has already been demonstrated in practice in a LDACS navigation has already been demonstrated in practice in a
flight measurement campaign [SCH20191]. flight measurement campaign [SCH20191].
6. Requirements to LDACS 6. Requirements to LDACS
The requirements to LDACS are mostly defined by its application area: The requirements to LDACS are mostly defined by its application area:
Communication related to safety and regularity of flight. Communication related to safety and regularity of flight.
A particularity of the current aeronautical communication landscape A particularity of the current aeronautical communication landscape
is that it is heavily regulated. Aeronautical data links (for is that it is heavily regulated. Aeronautical data links (for
applications related to safety and regularity of flight) may only use applications related to safety and regularity of flight) MAY only use
spectrum licensed to aviation and data links endorsed by ICAO. spectrum licensed to aviation and data links endorsed by ICAO.
Nation states can change this locally, however, due to the global Nation states can change this locally, however, due to the global
scale of the air transportation system adherence to these practices scale of the air transportation system adherence to these practices
is to be expected. is to be expected.
Aeronautical data links for the Aeronautical Telecommunication Aeronautical data links for the Aeronautical Telecommunication
Network (ATN) are therefore expected to remain in service for Network (ATN) are therefore expected to remain in service for
decades. The VDLM2 data link currently used for digital terrestrial decades. The VDLM2 data link currently used for digital terrestrial
internetworking was developed in the 1990es (the use of the Open internetworking was developed in the 1990es (the use of the Open
Systems Interconnection (OSI) stack indicates that as well). VDLM2 Systems Interconnection (OSI) stack indicates that as well). VDLM2
skipping to change at page 12, line 34 skipping to change at page 12, line 34
Current ATS applications use either the Aircraft Communications Current ATS applications use either the Aircraft Communications
Addressing and Reporting System (ACARS) or the OSI stack. The Addressing and Reporting System (ACARS) or the OSI stack. The
objective of the development effort LDACS as part of the FCI is to objective of the development effort LDACS as part of the FCI is to
replace legacy OSI stack and proprietary ACARS internetwork replace legacy OSI stack and proprietary ACARS internetwork
technologies with industry standard IP technology. It is anticipated technologies with industry standard IP technology. It is anticipated
that the use of Commercial Off-The-Shelf (COTS) IP technology mostly that the use of Commercial Off-The-Shelf (COTS) IP technology mostly
applies to the ground network. The avionics networks on the aircraft applies to the ground network. The avionics networks on the aircraft
will likely be heavily modified or proprietary. will likely be heavily modified or proprietary.
AOC applications currently mostly use the same stack (although some AOC applications currently mostly use the same stack (although some
applications, like the graphical weather service may use the applications, like the graphical weather service MAY use the
commercial passenger network). This creates capacity problems commercial passenger network). This creates capacity problems
(resulting in excessive amounts of timeouts) since the underlying (resulting in excessive amounts of timeouts) since the underlying
terrestrial data links (VDLM1/2) do not provide sufficient bandwidth. terrestrial data links (VDLM1/2) do not provide sufficient bandwidth.
The use of non-aviation specific data links is considered a security The use of non-aviation specific data links is considered a security
problem. Ideally the aeronautical IP internetwork and the Internet problem. Ideally the aeronautical IP internetwork and the Internet
should be completely separated. SHOULD be completely separated.
The objective of LDACS is to provide a next generation terrestrial The objective of LDACS is to provide a next generation terrestrial
data link designed to support IP and provide much higher bandwidth to data link designed to support IP and provide much higher bandwidth to
avoid the currently experienced operational problems. avoid the currently experienced operational problems.
The requirement for LDACS is therefore to provide a terrestrial high- The requirement for LDACS is therefore to provide a terrestrial high-
throughput data link for IP internetworking in the aircraft. throughput data link for IP internetworking in the aircraft.
In order to fulfil the above requirement LDACS needs to be In order to fulfil the above requirement LDACS needs to be
interoperable with IP (and IP-based services like Voice-over-IP) at interoperable with IP (and IP-based services like Voice-over-IP) at
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In addition to the functional requirements LDACS and its IP stack In addition to the functional requirements LDACS and its IP stack
need to fulfil the requirements defined in RTCA DO-350A/EUROCAE ED- need to fulfil the requirements defined in RTCA DO-350A/EUROCAE ED-
228A [DO350A]. This document defines continuity, availability, and 228A [DO350A]. This document defines continuity, availability, and
integrity requirements at different scopes for each air traffic integrity requirements at different scopes for each air traffic
management application (CPDLC, CM, and ADS-C). The scope most management application (CPDLC, CM, and ADS-C). The scope most
relevant to IP over LDACS is the CSP (Communication Service Provider) relevant to IP over LDACS is the CSP (Communication Service Provider)
scope. scope.
Continuity, availability, and integrity requirements are defined in Continuity, availability, and integrity requirements are defined in
[DO350A] volume 1 Table 5-14, and Table 6-13. Appendix A presents [DO350A] volume 1 Table 5-14, and Table 6-13. Appendix A presents
the required information. the REQUIRED information.
In a similar vein, requirements to fault management are defined in In a similar vein, requirements to fault management are defined in
the same tables. the same tables.
7. Characteristics of LDACS 7. Characteristics of LDACS
LDACS will become one of several wireless access networks connecting LDACS will become one of several wireless access networks connecting
aircraft to the ATN implemented by the FCI and possibly ACARS/FANS aircraft to the ATN implemented by the FCI and possibly ACARS/FANS
networks [FAN2019]. networks [FAN2019].
skipping to change at page 15, line 25 skipping to change at page 15, line 25
access sub-layer manages the organization of transmission access sub-layer manages the organization of transmission
opportunities in slots of time and frequency. The LLC sub-layer opportunities in slots of time and frequency. The LLC sub-layer
provides acknowledged point-to-point logical channels between the provides acknowledged point-to-point logical channels between the
aircraft and the GS using an automatic repeat request protocol. aircraft and the GS using an automatic repeat request protocol.
LDACS supports also unacknowledged point-to-point channels and G2A LDACS supports also unacknowledged point-to-point channels and G2A
broadcast. broadcast.
7.5. LDACS Mobility 7.5. LDACS Mobility
LDACS supports layer 2 handovers to different LDACS channels. LDACS supports layer 2 handovers to different LDACS channels.
Handovers may be initiated by the aircraft (break-before-make) or by Handovers MAY be initiated by the aircraft (break-before-make) or by
the GS (make-before-break). Make-before-break handovers are only the GS (make-before-break). Make-before-break handovers are only
supported for GSs connected to the same GSC. supported for GSs connected to the same GSC.
External handovers between non-connected LDACS sub-networks or External handovers between non-connected LDACS sub-networks or
different aeronautical data links shall be handled by the FCI multi- different aeronautical data links SHALL be handled by the FCI multi-
link concept. link concept.
8. Reliability and Availability 8. Reliability and Availability
8.1. Layer 2 8.1. Layer 2
LDACS has been designed with applications related to the safety and LDACS has been designed with applications related to the safety and
regularity of flight in mind. It has therefore been designed as a regularity of flight in mind. It has therefore been designed as a
deterministic wireless data link (as far as this is possible). deterministic wireless data link (as far as this is possible).
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have multiple independent data link technologies in the aircraft have multiple independent data link technologies in the aircraft
(e.g., terrestrial and SatCom) in addition to legacy VHF voice. (e.g., terrestrial and SatCom) in addition to legacy VHF voice.
However, as of now no reliability and availability mechanisms that However, as of now no reliability and availability mechanisms that
could utilize the multi-link have been specified on Layer 3 and could utilize the multi-link have been specified on Layer 3 and
above. above.
Below Layer 2 aeronautics usually relies on hardware redundancy. To Below Layer 2 aeronautics usually relies on hardware redundancy. To
protect availability of the LDACS link, an aircraft equipped with protect availability of the LDACS link, an aircraft equipped with
LDACS will have access to two L-band antennae with triple redundant LDACS will have access to two L-band antennae with triple redundant
radio systems as required for any safety relevant system by ICAO. radio systems as REQUIRED for any safety relevant system by ICAO.
9. Protocol Stack 9. Protocol Stack
The protocol stack of LDACS is implemented in the AS, GS, and GSC: It The protocol stack of LDACS is implemented in the AS, GS, and GSC: It
consists of the Physical Layer (PHY) with five major functional consists of the Physical Layer (PHY) with five major functional
blocks above it. Four are placed in the Data Link Layer (DLL) of the blocks above it. Four are placed in the Data Link Layer (DLL) of the
AS and GS: (1) Medium Access Layer (MAC), (2) Voice Interface (VI), AS and GS: (1) Medium Access Layer (MAC), (2) Voice Interface (VI),
(3) Data Link Service (DLS), and (4) LDACS Management Entity (LME). (3) Data Link Service (DLS), and (4) LDACS Management Entity (LME).
The last entity resides within the Sub-Network Layer: Sub-Network The last entity resides within the Sub-Network Layer: Sub-Network
Protocol (SNP). The LDACS network is externally connected to voice Protocol (SNP). The LDACS network is externally connected to voice
skipping to change at page 21, line 30 skipping to change at page 21, line 30
Figure 4: MF structure for LDACS Figure 4: MF structure for LDACS
9.2. DLS Entity Services 9.2. DLS Entity Services
The DLS provides acknowledged and unacknowledged (including broadcast The DLS provides acknowledged and unacknowledged (including broadcast
and packet mode voice) bi-directional exchange of user data. If user and packet mode voice) bi-directional exchange of user data. If user
data is transmitted using the acknowledged DLS, the sending DLS data is transmitted using the acknowledged DLS, the sending DLS
entity will wait for an acknowledgement from the receiver. If no entity will wait for an acknowledgement from the receiver. If no
acknowledgement is received within a specified time frame, the sender acknowledgement is received within a specified time frame, the sender
may automatically try to retransmit its data. However, after a MAY automatically try to retransmit its data. However, after a
certain number of failed retries, the sender will suspend further certain number of failed retries, the sender will suspend further
retransmission attempts and inform its client of the failure. retransmission attempts and inform its client of the failure.
The DLS uses the logical channels provided by the MAC: The DLS uses the logical channels provided by the MAC:
1. A GS announces its existence and access parameters in the 1. A GS announces its existence and access parameters in the
Broadcast Channel (BC). Broadcast Channel (BC).
2. The RA channel enables AS to request access to an LDACS cell. 2. The RA channel enables AS to request access to an LDACS cell.
3. In the FL the CCCH is used by the GS to grant access to data 3. In the FL the CCCH is used by the GS to grant access to data
channel resources. channel resources.
4. The reverse direction is covered by the RL, where ASs need to 4. The reverse direction is covered by the RL, where ASs need to
request resources before sending. This happens via the DCCH. request resources before sending. This happens via the DCCH.
5. User data itself is communicated in the Data Channel (DCH) on the 5. User data itself is communicated in the Data Channel (DCH) on the
FL and RL. FL and RL.
9.3. VI Services 9.3. VI Services
The VI provides support for virtual voice circuits. Voice circuits The VI provides support for virtual voice circuits. Voice circuits
may either be set-up permanently by the GS (e.g., to emulate voice MAY either be set-up permanently by the GS (e.g., to emulate voice
party line) or may be created on demand. The creation and selection party line) or MAY be created on demand. The creation and selection
of voice circuits is performed in the LME. The VI provides only the of voice circuits is performed in the LME. The VI provides only the
transmission services. transmission services.
9.4. LME Services 9.4. LME Services
The mobility management service in the LME provides support for The mobility management service in the LME provides support for
registration and de-registration (cell entry and cell exit), scanning registration and de-registration (cell entry and cell exit), scanning
RF channels of neighboring cells and handover between cells. In RF channels of neighboring cells and handover between cells. In
addition, it manages the addressing of aircraft/ ASs within cells. addition, it manages the addressing of aircraft/ ASs within cells.
It is controlled by the network management service in the GSC. It is controlled by the network management service in the GSC.
The resource management service provides link maintenance (power, The resource management service provides link maintenance (power,
frequency and time adjustments), support for adaptive coding and frequency and time adjustments), support for adaptive coding and
modulation, and resource allocation. modulation, and resource allocation.
9.5. SNP Services 9.5. SNP Services
The DLS provides functions required for the transfer of user plane The DLS provides functions REQUIRED for the transfer of user plane
data and control plane data over the LDACS sub-network. data and control plane data over the LDACS sub-network.
The security service provides functions for secure communication over The security service provides functions for secure communication over
the LDACS sub-network. Note that the SNP security service applies the LDACS sub-network. Note that the SNP security service applies
cryptographic measures as configured by the GSC. cryptographic measures as configured by the GSC.
10. Security Considerations 10. Security Considerations
10.1. Reasons for Wireless Digital Aeronautical Communications 10.1. Reasons for Wireless Digital Aeronautical Communications
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As digitalization progresses even further with LDACS and automated As digitalization progresses even further with LDACS and automated
procedures such as 4D-Trajectories allowing semi-automated en-route procedures such as 4D-Trajectories allowing semi-automated en-route
flying of aircraft, LDACS requires stronger cybersecurity measures. flying of aircraft, LDACS requires stronger cybersecurity measures.
10.2. Requirements for LDACS 10.2. Requirements for LDACS
Overall there are several business goals for cybersecurity to protect Overall there are several business goals for cybersecurity to protect
in FCI in civil aviation: in FCI in civil aviation:
1. Safety: The system must sufficiently mitigate attacks, which 1. Safety: The system MUST sufficiently mitigate attacks, which
contribute to safety hazards. contribute to safety hazards.
2. Flight regularity: The system must sufficiently mitigate attacks, 2. Flight regularity: The system MUST sufficiently mitigate attacks,
which contribute to delays, diversions, or cancellations of which contribute to delays, diversions, or cancellations of
flights. flights.
3. Protection of business interests: The system must sufficiently 3. Protection of business interests: The system MUST sufficiently
mitigate attacks which result in financial loss, reputation mitigate attacks which result in financial loss, reputation
damage, disclosure of sensitive proprietary information, or damage, disclosure of sensitive proprietary information, or
disclosure of personal information. disclosure of personal information.
To further analyze assets and derive threats and thus protection To further analyze assets and derive threats and thus protection
scenarios several Threat-and Risk Analysis were performed for LDACS scenarios several Threat-and Risk Analysis were performed for LDACS
[MAE20181] , [MAE20191]. These results allowed deriving security [MAE20181] , [MAE20191]. These results allowed deriving security
scope and objectives from the requirements and the conducted Threat- scope and objectives from the requirements and the conducted Threat-
and Risk Analysis. and Risk Analysis.
10.3. Security Objectives for LDACS 10.3. Security Objectives for LDACS
Security considerations for LDACS are defined by the official Security considerations for LDACS are defined by the official
Standards And Recommended Practices document by ICAO [ICA2018]: Standards And Recommended Practices document by ICAO [ICA2018]:
1. LDACS shall provide a capability to protect the availability and 1. LDACS SHALL provide a capability to protect the availability and
continuity of the system. continuity of the system.
2. LDACS shall provide a capability including cryptographic 2. LDACS SHALL provide a capability including cryptographic
mechanisms to protect the integrity of messages in transit. mechanisms to protect the integrity of messages in transit.
3. LDACS shall provide a capability to ensure the authenticity of 3. LDACS SHALL provide a capability to ensure the authenticity of
messages in transit. messages in transit.
4. LDACS should provide a capability for nonrepudiation of origin 4. LDACS SHOULD provide a capability for nonrepudiation of origin
for messages in transit. for messages in transit.
5. LDACS should provide a capability to protect the confidentiality 5. LDACS SHOULD provide a capability to protect the confidentiality
of messages in transit. of messages in transit.
6. LDACS shall provide an authentication capability. 6. LDACS SHALL provide an authentication capability.
7. LDACS shall provide a capability to authorize the permitted 7. LDACS SHALL provide a capability to authorize the permitted
actions of users of the system and to deny actions that are not actions of users of the system and to deny actions that are not
explicitly authorized. explicitly authorized.
8. If LDACS provides interfaces to multiple domains, LDACS shall 8. If LDACS provides interfaces to multiple domains, LDACS SHALL
provide capability to prevent the propagation of intrusions within provide capability to prevent the propagation of intrusions within
LDACS domains and towards external domains. LDACS domains and towards external domains.
10.4. Security Functions for LDACS 10.4. Security Functions for LDACS
These objectives were used to derive several security functions for These objectives were used to derive several security functions for
LDACS required to be integrated in the LDACS cybersecurity LDACS REQUIRED to be integrated in the LDACS cybersecurity
architecture: (1) Identification, (2) Authentication, (3) architecture: (1) Identification, (2) Authentication, (3)
Authorization, (4) Confidentiality, (5) System Integrity, (6) Data Authorization, (4) Confidentiality, (5) System Integrity, (6) Data
Integrity, (7) Robustness, (8) Reliability, (9) Availability, and Integrity, (7) Robustness, (8) Reliability, (9) Availability, and
(10) Key and Trust Management. Several works investigated possible (10) Key and Trust Management. Several works investigated possible
measures to implement these security functions [BIL2017], [MAE20181], measures to implement these security functions [BIL2017], [MAE20181],
[MAE20191]. Having identified security requirements, objectives and [MAE20191]. Having identified security requirements, objectives and
functions it MUST be ensured that they are applicable. functions it MUST be ensured that they are applicable.
10.5. Security Architectural Details for LDACS 10.5. Security Architectural Details for LDACS
skipping to change at page 25, line 43 skipping to change at page 25, line 43
GS could be identified using a similar field. And again similar to GS could be identified using a similar field. And again similar to
4G's Mobility Management Entities (MME), a GSC could be identified 4G's Mobility Management Entities (MME), a GSC could be identified
using similar identification fields within the LDACS network. The using similar identification fields within the LDACS network. The
identification of the network operator is again similar to 4G (e.g., identification of the network operator is again similar to 4G (e.g.,
E-Plus, AT&T, and TELUS), in the way that the aeronautical network E-Plus, AT&T, and TELUS), in the way that the aeronautical network
operators are listed (e.g., ARINC [ARI2020] and SITA [SIT2020]). operators are listed (e.g., ARINC [ARI2020] and SITA [SIT2020]).
10.5.3. Matter of LDACS Entity Authentication and Key Negotiation 10.5.3. Matter of LDACS Entity Authentication and Key Negotiation
In order to anchor Trust within the system all LDACS entities In order to anchor Trust within the system all LDACS entities
connected to the ground IPS network shall be rooted in an LDACS connected to the ground IPS network SHALL be rooted in an LDACS
specific chain-of-trust and PKI solution, quite similar to AeroMACS specific chain-of-trust and PKI solution, quite similar to AeroMACS
approach [CRO2016]. These X.509 certificates [RFC5280] residing at approach [CRO2016]. These X.509 certificates [RFC5280] residing at
the entities and incorporated in the LDACS PKI proof the ownership of the entities and incorporated in the LDACS PKI proof the ownership of
their respective public key, include information about the identity their respective public key, include information about the identity
of the owner and the digital signature of the entity that has of the owner and the digital signature of the entity that has
verified the certificate's content. First all ground infrastructures verified the certificate's content. First all ground infrastructures
must mutually authenticate to each other, negotiate and derive keys MUST mutually authenticate to each other, negotiate and derive keys
and, thus, secure all ground connections. How this process is and, thus, secure all ground connections. How this process is
handled in detail is still an ongoing discussion. However, handled in detail is still an ongoing discussion. However,
established methods to secure user plane by IPSec [RFC4301] and IKEv2 established methods to secure user plane by IPSec [RFC4301] and IKEv2
[RFC7296] or the application layer via TLS 1.3 [RFC8446] are [RFC7296] or the application layer via TLS 1.3 [RFC8446] are
conceivable. The LDACS PKI with their chain-of-trust approach, conceivable. The LDACS PKI with their chain-of-trust approach,
digital certificates and public entity keys lay the groundwork for digital certificates and public entity keys lay the groundwork for
this step. In a second step the AS with the LDACS radio approaches this step. In a second step the AS with the LDACS radio approaches
an LDACS cell and performs a cell entry with the corresponding GS. an LDACS cell and performs a cell entry with the corresponding GS.
Similar to the LTE cell attachment process [TS33.401], where Similar to the LTE cell attachment process [TS33.401], where
authentication happens after basic communication has been enabled authentication happens after basic communication has been enabled
skipping to change at page 26, line 48 skipping to change at page 26, line 48
[MAE20192], and [MAE2020]. It proposes the use of an own LDACS PKI, [MAE20192], and [MAE2020]. It proposes the use of an own LDACS PKI,
identity management based on aircraft identities and network operator identity management based on aircraft identities and network operator
identities (e.g., SITA and ARINC), public key certificates identities (e.g., SITA and ARINC), public key certificates
incorporated in the PKI based chain-of-trust and stored in the incorporated in the PKI based chain-of-trust and stored in the
entities allowing for mutual authentication and key exchange entities allowing for mutual authentication and key exchange
procedures, key derivation mechanisms for perfect forward secrecy and procedures, key derivation mechanisms for perfect forward secrecy and
user/control plane message-in-transit integrity and confidentiality user/control plane message-in-transit integrity and confidentiality
protection. This secures data traveling over the airgap between AS protection. This secures data traveling over the airgap between AS
and GS and also between GS and ANSP regardless of the secure or and GS and also between GS and ANSP regardless of the secure or
unsecure nature of application data. Of course application data unsecure nature of application data. Of course application data
itself must be additionally secured to achieve end-to-end security itself MUST be additionally secured to achieve end-to-end security
(secure dialogue service), however the LDACS datalinks aims to (secure dialogue service), however the LDACS datalinks aims to
provide an additional layer of protection just for this network provide an additional layer of protection just for this network
segment. segment.
11. Privacy Considerations 11. Privacy Considerations
LDACS provides a Quality-of-Service, and the generic considerations LDACS provides a Quality-of-Service, and the generic considerations
for such mechanisms apply. for such mechanisms apply.
12. IANA Considerations 12. IANA Considerations
skipping to change at page 27, line 46 skipping to change at page 27, line 46
[RFC7296] Kaufman, C., Hoffman, P., Nir, Y., Eronen, P., and T. [RFC7296] Kaufman, C., Hoffman, P., Nir, Y., Eronen, P., and T.
Kivinen, "Internet Key Exchange Protocol Version 2 Kivinen, "Internet Key Exchange Protocol Version 2
(IKEv2)", STD 79, RFC 7296, DOI 10.17487/RFC7296, October (IKEv2)", STD 79, RFC 7296, DOI 10.17487/RFC7296, October
2014, <https://www.rfc-editor.org/info/rfc7296>. 2014, <https://www.rfc-editor.org/info/rfc7296>.
[RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol [RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018, Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
<https://www.rfc-editor.org/info/rfc8446>. <https://www.rfc-editor.org/info/rfc8446>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
15. Informative References 15. Informative References
[SCHN2016] Schneckenburger, N., Jost, T., Shutin, D., Walter, M., [SCHN2016] Schneckenburger, N., Jost, T., Shutin, D., Walter, M.,
Thiasiriphet, T., Schnell, M., and U.C. Fiebig, Thiasiriphet, T., Schnell, M., and U.C. Fiebig,
"Measurement of the L-band Air-to-Ground Channel for "Measurement of the L-band Air-to-Ground Channel for
Positioning Applications", IEEE Transactions on Aerospace Positioning Applications", IEEE Transactions on Aerospace
and Electronic Systems, 52(5), pp.2281-229 , 2016. and Electronic Systems, 52(5), pp.2281-229 , 2016.
[MAE20191] Maeurer, N., Graeupl, T., and C. Schmitt, "Evaluation of [MAE20191] Maeurer, N., Graeupl, T., and C. Schmitt, "Evaluation of
the LDACS Cybersecurity Implementation", IEEE 38th Digital the LDACS Cybersecurity Implementation", IEEE 38th Digital
skipping to change at page 30, line 33 skipping to change at page 30, line 39
[DO350A] RTCA SC-214, "Safety and Performance Standard for Baseline [DO350A] RTCA SC-214, "Safety and Performance Standard for Baseline
2 ATS Data Communications (Baseline 2 SPR Standard)", May 2 ATS Data Communications (Baseline 2 SPR Standard)", May
2016, <https://standards.globalspec.com/std/10003192/rtca- 2016, <https://standards.globalspec.com/std/10003192/rtca-
do-350-volume-1-2>. do-350-volume-1-2>.
[RAW-TECHNOS] [RAW-TECHNOS]
Thubert, P., Cavalcanti, D., Vilajosana, X., Schmitt, C., Thubert, P., Cavalcanti, D., Vilajosana, X., Schmitt, C.,
and J. Farkas, "Reliable and Available Wireless and J. Farkas, "Reliable and Available Wireless
Technologies", Work in Progress, Internet-Draft, draft- Technologies", Work in Progress, Internet-Draft, draft-
thubert-raw-technologies-05, 18 May 2020, ietf-raw-technologies-00, 20 October 2020,
<https://tools.ietf.org/html/draft-thubert-raw- <https://tools.ietf.org/html/draft-ietf-raw-technologies-
technologies-05>. 00>.
[RAW-USE-CASES] [RAW-USE-CASES]
Papadopoulos, G., Thubert, P., Theoleyre, F., and C. Papadopoulos, G., Thubert, P., Theoleyre, F., and C.
Bernardos, "RAW use cases", Work in Progress, Internet- Bernardos, "RAW use cases", Work in Progress, Internet-
Draft, draft-bernardos-raw-use-cases-04, 13 July 2020, Draft, draft-ietf-raw-use-cases-00, 23 October 2020,
<https://tools.ietf.org/html/draft-bernardos-raw-use- <https://tools.ietf.org/html/draft-ietf-raw-use-cases-00>.
cases-04>.
Appendix A. Selected Information from DO-350A Appendix A. Selected Information from DO-350A
This appendix includes the continuity, availability, and integrity This appendix includes the continuity, availability, and integrity
requirements interesting for LDACS defined in [DO350A]. requirements interesting for LDACS defined in [DO350A].
The following terms are used here: The following terms are used here:
CPDLC Controller Pilot Data Link Communication CPDLC Controller Pilot Data Link Communication
DT Delivery Time (nominal) value for RSP DT Delivery Time (nominal) value for RSP
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| | (safety) | (efficiency) | | | | | (safety) | (efficiency) | | |
+--------------+----------+--------------+---------+---------+ +--------------+----------+--------------+---------+---------+
| Integrity | 1E-5 per | 1E-5 per FH | 1E-5 | 1E-5 | | Integrity | 1E-5 per | 1E-5 per FH | 1E-5 | 1E-5 |
| | FH | | per FH | per FH | | | FH | | per FH | per FH |
+--------------+----------+--------------+---------+---------+ +--------------+----------+--------------+---------+---------+
Table 2: CPDLC Requirements for RCP Table 2: CPDLC Requirements for RCP
RCP Monitoring and Alerting Criteria in case of CPDLC: RCP Monitoring and Alerting Criteria in case of CPDLC:
- MA-1: The system shall be capable of detecting failures and - MA-1: The system SHALL be capable of detecting failures and
configuration changes that would cause the communication service configuration changes that would cause the communication service
no longer meet the RCP specification for the intended use. no longer meet the RCP specification for the intended use.
- MA-2: When the communication service can no longer meet the RCP - MA-2: When the communication service can no longer meet the RCP
specification for the intended function, the flight crew and/or specification for the intended function, the flight crew and/or
the controller shall take appropriate action. the controller SHALL take appropriate action.
+==============+=====+=====+==========+==============+======+=======+ +==============+=====+=====+==========+==============+======+=======+
| | RSP | RSP | RSP 180 | RSP 180 | RSP |RSP 400| | | RSP | RSP | RSP 180 | RSP 180 | RSP |RSP 400|
| | 160 | 160 | | | 400 | | | | 160 | 160 | | | 400 | |
+==============+=====+=====+==========+==============+======+=======+ +==============+=====+=====+==========+==============+======+=======+
| Parameter | OT |DT95%| OT | DT95% | OT | DT95% | | Parameter | OT |DT95%| OT | DT95% | OT | DT95% |
+--------------+-----+-----+----------+--------------+------+-------+ +--------------+-----+-----+----------+--------------+------+-------+
| Transaction | 160 | 90 | 180 | 90 | 400 | 300 | | Transaction | 160 | 90 | 180 | 90 | 400 | 300 |
| Time (sec) | | | | | | | | Time (sec) | | | | | | |
+--------------+-----+-----+----------+--------------+------+-------+ +--------------+-----+-----+----------+--------------+------+-------+
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+--------------+-----+-----+----------+--------------+------+-------+ +--------------+-----+-----+----------+--------------+------+-------+
| Integrity | 1E-5| 1E-5| 1E-5 per | 1E-5 per FH | 1E-5 | 1E-5 | | Integrity | 1E-5| 1E-5| 1E-5 per | 1E-5 per FH | 1E-5 | 1E-5 |
| | per | per | FH | |per FH| per FH| | | per | per | FH | |per FH| per FH|
| | FH | FH | | | | | | | FH | FH | | | | |
+--------------+-----+-----+----------+--------------+------+-------+ +--------------+-----+-----+----------+--------------+------+-------+
Table 3: ADS-C Requirements Table 3: ADS-C Requirements
RCP Monitoring and Alerting Criteria: RCP Monitoring and Alerting Criteria:
- MA-1: The system shall be capable of detecting failures and - MA-1: The system SHALL be capable of detecting failures and
configuration changes that would cause the ADS-C service no longer configuration changes that would cause the ADS-C service no longer
meet the RSP specification for the intended function. meet the RSP specification for the intended function.
- MA-2: When the ADS-C service can no longer meet the RSP - MA-2: When the ADS-C service can no longer meet the RSP
specification for the intended function, the flight crew and/or specification for the intended function, the flight crew and/or
the controller shall take appropriate action. the controller SHALL take appropriate action.
Authors' Addresses Authors' Addresses
Nils Maeurer (editor) Nils Maeurer (editor)
German Aerospace Center (DLR) German Aerospace Center (DLR)
Muenchner Strasse 20 Muenchner Strasse 20
82234 Wessling 82234 Wessling
Germany Germany
Email: Nils.Maeurer@dlr.de Email: Nils.Maeurer@dlr.de
Thomas Graeupl (editor) Thomas Graeupl (editor)
German Aerospace Center (DLR) German Aerospace Center (DLR)
Muenchner Strasse 20 Muenchner Strasse 20
82234 Wessling 82234 Wessling
Germany Germany
Email: Thomas.Graeupl@dlr.de Email: Thomas.Graeupl@dlr.de
Corinna Schmitt (editor) Corinna Schmitt (editor)
Research Institute CODE, UniBwM Research Institute CODE, UniBwM
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