SIST EN 301 842-4 V1.3.1:2015
VHF air-ground Digital Link (VDL) Mode 4 radio equipment; Technical characteristics and methods of measurement for ground-based equipment; Part 4: Point-to-point functions
VHF air-ground Digital Link (VDL) Mode 4 radio equipment; Technical characteristics and methods of measurement for ground-based equipment; Part 4: Point-to-point functions
The present document applies to the following radio equipment types:
1) Very High Frequency (VHF) Digital Link (VDL) Mode 4 ground-based radio transmitters and receivers for
air-ground communications operating in the VHF band, using Gaussian-filtered Frequency Shift Keying (GFSK)
Modulation with 25 kHz channel spacing and capable of tuning to any of the 25 kHz channels from
112,000 MHz to 136,975 MHz as defined in ICAO VHF Digital Link (VDL) Standards and Recommended
Practices (SARPs) [7].
The present document provides part 4 of the technical specifications.
The present document is designed to ensure that equipment certified to it will be compatible with the relevant ICAO
VHF Digital Link (VDL) Standards and Recommended Practices (SARPs) [7] and VDL Mode 4 Technical Manual
(TM) [1].
Manufacturers should note that in future the tuning range for the ground transceivers may also cover any 25 kHz
channel from 108,000 MHz to 111,975 MHz.
The scope of the present document is limited to ground stations. The equivalent specification for airborne stations is
ETSI EN 302 842 [i.1].
A description of the scope of the VDL Mode 4 system is provided in part 2 of these technical specifications
(see ETSI EN 301 842-2 [5], clause 1).
ETSI EN 301 842-1 [4] deals with tests of the physical layer, ETSI EN 301 842-2 [5] deals with core link layer
functionality and ETSI EN 301 842-3 [6] with additional broadcast functionality. The present document deals with tests
of the datalink service (DLS) layer and the link layer sufficient to support point-to-point functionality.
The present document is organized as follows:
• clause 2 provides references to relevant documents;
• clause 3 provides general definitions, abbreviations and symbols used;
• clause 4 describes the VDL Mode 4 ground station point-to-point functions;
• clause 5 provides performance specifications for the VDL Mode 4 ground station;
• clause 6 provides general design requirements;
• clause 7 provides protocol tests for the point-to-point functions of the system;
• annex A provides a detailed cross-reference to the relevant requirements contained in [1];
• annex B provides a Bibliography.
Note that the system can support a very wide range of functions. It is not practical to provide specific tests for all
aspects of functionality. The approach used is to provide detailed tests for the core point-to-point functionality and
to provide tests of those remaining requirements which, if wrongly implemented, could cause a deterioration in the
service offered by other VDL Mode 4 stations.
Mandating and Recommendation Phrases
a) "Shall":
- the use of the word "Shall" indicates a mandated criterion; i.e. compliance with the particular procedure
or specification is mandatory and no alternative may be applied.
b) "Should":
- the use of the word "Should" (and phrases such as "It is recommended that...", etc.) indicates that though
the procedure or criterion is regarded as the preferred option, alternative procedures, specifications or
criteria may be applied, provided that the manufacturer, installer or tester can provide information or data
to adequately support and justify the alternative
Radijska oprema za digitalno povezavo VHF zrak-tla, 4. način - Tehnične karakteristike in merilne metode za talno opremo - 4. del: Funkcije sistema točka-točka
Ta dokument se uporablja za radijsko opremo naslednjih vrst:
1) talne radijske oddajnike in sprejemnike za zelo visokofrekvenčno (VHF) digitalno povezavo (VDL) za komunikacije zrak-tla, 4. način, ki delujejo v pasu VHF z uporabo modulacije frekvenčnega premičnega kodiranja prek filtra Gaussian (GFSK) z razmikom 25 kHz med kanali in so zmožni uravnavati na katerem koli izmed kanalov 25 kHz od 112,000 MHz do 136,975 MHz, kot je opredeljeno v standardih in priporočenih praksah (SARP) [7] za digitalne povezave ICAO VHF (VDL).
Ta dokument vsebuje 4. del tehničnih specifikacij.
Ta dokument zagotavlja, da bo oprema, ki bo certificirana v skladu z njim, združljiva z ustreznimi standardi in priporočenimi praksami (SARP) [7] za digitalne povezave ICAO VHF (VDL) in tehničnim priročnikom ICAO za digitalno povezavo VDL, 4. način (TM) [1].
Proizvajalci naj bodo pozorni, da razpon uravnavanja za talne oddajnike-sprejemnike lahko v prihodnje zajema tudi kateri koli kanal 25 kHz od 108,000 MHz do 111,975 MHz.
Področje uporabe tega dokumenta je omejeno na zemeljske postaje. Enakovredna specifikacija za letalske postaje je ETSI EN 302 842 [i.1].
Opis področja uporabe sistema VDL, 4. način, je naveden v 2. delu teh tehničnih specifikacij (glej ETSI EN 301 842-2 [5], 1. točka).
Standard ETSI EN 301 842-1 [4] obravnava preskuse fizične plasti, standard ETSI EN 301 842-2 [5] obravnava temeljno funkcionalnost podatkovne povezave, standard ETSI EN 301 842-3 [6] pa dodatno funkcionalnost v zvezi z radiodifuzijo. Ta dokument zajema preskuse
plasti za podatkovne povezave (DLS) in plasti povezav, ki zadostujejo za podporo funkcij točka-točka.
Ta dokument je organiziran na naslednji način:
• točka 2 vsebuje sklice do ustreznih dokumentov;
• točka 3 vsebuje splošne opredelitve, kratice in simbole, ki se uporabljajo;
• točka 4 vsebuje funkcije točka-točka zemeljske postaje VDL, 4. način;
• točka 5 vsebuje specifikacije lastnosti zemeljskih postaj VDL, 4. način;
• točka 6 vsebuje splošne zahteve projekta;
• točka 7 vsebuje preskuse protokolov za funkcije točka-točka sistema;
• dodatek A vsebuje podrobne sklice do ustreznih zahtev, ki so vključene v [1];
• dodatek B vsebuje bibliografijo.
Upoštevati je treba, da lahko sistem podpira zelo širok nabor funkcij. Podajanje določenih preskusov za celoten nabor funkcij ni praktično. Tako so podani podrobni preskusi za osrednje funkcije točka-točka in preskusi tistih preostalih zahtev, ki lahko v primeru nepravilnega izvajanja povzročijo poslabšanje storitve, ki jo zagotavljajo druge postaje VDL, 4. način.
Izražanje zahtev in priporočil
a) »Je treba«:
– uporaba izraza »je treba« pomeni obvezno merilo, tj. skladnost z določenim postopkom ali specifikacijo je nujna, pri čemer uporaba alternativ ni dovoljena.
b) »Naj bi«:
– uporaba izraza »naj bi« (in izrazov, kot je »priporočljivo je, da ...« itd.) pomeni, da se lahko namesto postopka ali merila, ki je sicer obravnavano kot prednostno, uporabijo tudi alternativni postopki, specifikacije ali merila, če lahko proizvajalec, monter ali preizkuševalec zagotovi informacije ali podatke, ki ustrezno podpirajo in upravičujejo alternativo
General Information
Standards Content (Sample)
Draft ETSI EN 301 842-4 V1.3.0 (2014-12)
EUROPEAN STANDARD
VHF air-ground Digital Link (VDL) Mode 4 radio equipment;
Technical characteristics and methods of measurement
for ground-based equipment;
Part 4: Point-to-point functions
2 Draft ETSI EN 301 842-4 V1.3.0 (2014-12)
Reference
REN/AERO-00020-4
Keywords
aeronautical, digital, radio, testing, VHF
ETSI
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ETSI
3 Draft ETSI EN 301 842-4 V1.3.0 (2014-12)
Contents
Intellectual Property Rights . 6
Foreword . 6
Modal verbs terminology . 6
Introduction . 7
1 Scope . 8
2 References . 9
2.1 Normative references . 9
2.2 Informative references . 10
3 Definitions and abbreviations . 10
3.1 Definitions . 10
3.1.1 Basic reference model definitions . 10
3.1.2 Service conventions definitions . 10
3.1.3 General definitio ns . 10
3.1.4 Definition of bit order . 10
3.2 Abbreviations . 11
4 General description of VDL Mode 4 ground station point-to-point services . 12
4.1 General . 12
4.2 Data Link Service (DLS) and Link Management Entity (LME) . 12
4.2.1 General . 12
4.2.2 DLS timers . 15
4.2.3 DLS counters . 15
4.2.4 Toggle bit (T) . 16
4.2.5 State variables (T and T ) . 16
t r
4.2.6 Initialize Bit (IB) . 16
4.2.7 More bit (M) . 16
4.2.8 Priority (pr) . 16
4.2.9 Message fragmentation and concatenation . 17
4.2.10 DLS procedures . 17
4.2.10.1 Selection of DLS procedures. 17
4.2.10.2 Short transmission procedures . 17
4.2.10.3 Long transmission procedures . 18
4.2.11 Linking transmissions . 19
4.2.11.1 Types of linking . 19
4.2.11.2 Combined RTS / DATA DLPDUs . 19
4.2.11.3 Combined DATA / ACK DLPDUs . 20
4.2.11.4 Combined RTS / ACK DLPDUs . 20
4.2.11.5 Combined CTS / ACK DLPDUs . 20
4.2.12 Ground-air link management . 20
4.2.13 Air-air link management . 20
4.3 Additional VSS Services . 20
5 Minimum performance specification under standard test conditions . 21
5.1 DLS Sublayer . 21
5.1.1 General . 21
5.1.1.1 Services . 21
5.1.1.2 Data transfer . 21
5.1.1.3 DATA DLPDU duplicate suppression and sequencing . 22
5.1.1.4 Error detection . 22
5.1.1.5 Station identification . 22
5.1.1.6 Broadcast addressing . 22
5.1.1.7 DLS Priority . 22
5.1.1.8 DLS Link control DLPDUs . 23
5.1.2 DLS protocol specification . 23
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4 Draft ETSI EN 301 842-4 V1.3.0 (2014-12)
5.1.2.1 State Variables . 23
5.1.2.2 DLS burst formats . 23
5.1.3 DLS system parameters . 27
5.1.4 DLS procedures . 27
5.1.4.1 Setting of re-transmission parameter . 27
5.1.4.2 Selection of user data packet for transmission . 28
5.1.4.3 Selection of transmission procedures . 29
5.1.4.4 Short transmission procedures . 30
5.1.4.5 Long transmission procedures . 31
5.1.4.6 No link with sender . 33
5.1.4.7 User data packet reception . 34
5.1.4.8 Receipt of ACK DLPDU . 34
5.1.4.9 Link reset . 35
5.1.4.10 Linking DLS DLPDU transmissions . 35
5.1.4.11 CTRL DLPDU . 36
5.2 Link management entity sublayer. 36
5.2.1 Services . 36
5.2.1.1 General . 36
5.2.1.2 Link provision . 37
5.2.1.3 Link change notifications . 37
5.2.1.4 CTRL DLPDU . 37
5.2.1.5 Broadcast link management burst . 38
5.2.2 Control (CTRL) parameter formats . 38
5.2.2.1 Encoding . 38
5.2.2.2 General purpose information parameters . 38
5.2.2.3 Mobile-initiated information parameters . 42
5.2.2.4 Ground-initiated modification parameters . 43
5.2.2.5 Ground-initiated information parameters . 46
5.2.3 LME timers and parameters . 48
5.2.3.1 General . 48
5.2.3.2 Timer TL1 (maximum link overlap time) . 49
5.2.3.3 Parameters TL2 (link initialization time) . 49
5.2.3.4 Timer TL4 (leave generation latency) . 49
5.2.4 CTRL DLPDU types and procedures . 50
5.2.5 CTRL transmission procedures . 53
5.2.5.1 Link connectivity procedures . 53
5.2.5.2 Ground Station Identification . 53
5.2.5.3 Link establishment . 53
5.2.5.4 Mobile-initiated handoff . 54
5.2.5.5 Mobile-requested ground-initiated handoff . 54
5.2.5.6 Ground-initiated handoff . 55
5.2.5.7 Ground-requested mobile-initiated handoff . 55
5.2.5.8 Ground-requested broadcast handoff . 55
5.2.5.9 Ground-commanded autotune . 56
5.2.6 VDL Mode 4 Mobile Subnetwork Dependent Convergence Function (SNDCF) . 56
5.2.6.1 Frame Mode SNDCF . 56
5.3 Additional VSS Requirements . 56
5.3.1 Additional VSS quality of service parameters . 56
5.3.1.1 Parameter Q5 (VSS retransmission parameters) . 56
5.3.2 Unicast request protocol specification . 57
5.3.2.1 Unicast request parameters. 57
5.3.2.2 Unicast request transmission procedures . 58
5.3.3 Information transfer request protocol specification . 58
5.3.3.1 Information transfer request parameters . 58
5.3.3.2 Information transfer request transmission procedures . 60
5.3.3.3 Information transfer request acknowledgement procedures . 60
5.3.4 Retransmission procedures . 60
6 General design requirements . 61
7 Protocol test procedures . 61
7.1 General . 61
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5 Draft ETSI EN 301 842-4 V1.3.0 (2014-12)
7.2 Required test rig . 61
7.3 Protocol test-suite description methodology . 62
7.4 Detailed protocol test procedures . 62
7.4.1 Test-suite overview . 62
7.4.2 Declarations . 64
7.4.3 Constraints . 64
7.4.3.1 Abbreviations . 64
7.4.3.1.1 Subfield mnemonics . 64
7.4.3.1.2 Special characters used in the subfield definitions . 65
7.4.3.1.3 Station addresses and positions . 65
7.4.3.1.4 VDL bursts . 66
7.4.3.2 Test cases . 96
7.4.3.2.1 Test case macros . 97
7.4.3.2.2 Test case descriptions . 99
Annex A (informative): Cross reference matrix . 154
Annex B (informative): Bibliography . 163
History . 164
ETSI
6 Draft ETSI EN 301 842-4 V1.3.0 (2014-12)
Intellectual Property Rights
IPRs essential or potentially essential to the present document may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found
in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in
respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web
server (http://ipr.etsi.org).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee
can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web
server) which are, or may be, or may become, essential to the present document.
Foreword
This draft European Standard (EN) has been produced by ETSI Technical Committee Aeronautics (AERO), and is now
submitted for the combined Public Enquiry and Vote phase of the ETSI standards EN Approval Procedure.
The present document is part 4 of a multi-part deliverable covering the VHF air-ground Digital Link (VDL) Mode 4
radio equipment; Technical characteristics and methods of measurement for ground-based equipment, as identified
below:
Part 1: "EN for ground equipment";
Part 2: "General description and data link layer";
Part 3: "Additional broadcast aspects";
Part 4: "Point-to-point functions";
Part 5: "Hamonized EN covering the essential requirements of article 3.2 of the R&TTE Directive".
The present document is accompanied by an equivalent airborne standard, ETSI EN 302 842 [i.1] Parts 1 to 4, covering
the VHF air-ground Digital Link (VDL) Mode 4 radio equipment; Technical characteristics and methods of
measurement for airborne equipment.
Proposed national transposition dates
Date of latest announcement of this EN (doa): 3 months after ETSI publication
Date of latest publication of new National Standard
or endorsement of this EN (dop/e): 6 months after doa
Date of withdrawal of any conflicting National Standard (dow): 18 months after doa
Modal verbs terminology
In the present document "shall", "shall not", "should", "should not", "may", "may not", "need", "need not", "will",
"will not", "can" and "cannot" are to be interpreted as described in clause 3.2 of the ETSI Drafting Rules (Verbal forms
for the expression of provisions).
"must" and "must not" are NOT allowed in ETSI deliverables except when used in direct citation.
ETSI
7 Draft ETSI EN 301 842-4 V1.3.0 (2014-12)
Introduction
The present document states the technical specifications for Very High Frequency (VHF) Digital Link (VDL) Mode 4
ground-based radio transmitters, transceivers and receivers for air-ground communications operating in the VHF band,
using Gaussian-filtered Frequency Shift Keying (GFSK) Modulation with 25 kHz channel spacing and capable of
tuning to any of the 25 kHz channels from 112,000 MHz to 136,975 MHz as defined in ICAO VHF Digital Link (VDL)
Standards and Recommended Practices (SARPs) [7].
The present document may be used to produce tests for the assessment of the performance of the equipment.
ETSI
8 Draft ETSI EN 301 842-4 V1.3.0 (2014-12)
1 Scope
The present document applies to the following radio equipment types:
1) Very High Frequency (VHF) Digital Link (VDL) Mode 4 ground-based radio transmitters and receivers for
air-ground communications operating in the VHF band, using Gaussian-filtered Frequency Shift Keying (GFSK)
Modulation with 25 kHz channel spacing and capable of tuning to any of the 25 kHz channels from
112,000 MHz to 136,975 MHz as defined in ICAO VHF Digital Link (VDL) Standards and Recommended
Practices (SARPs) [7].
The present document provides part 4 of the technical specifications.
The present document is designed to ensure that equipment certified to it will be compatible with the relevant ICAO
VHF Digital Link (VDL) Standards and Recommended Practices (SARPs) [7] and VDL Mode 4 Technical Manual
(TM) [1].
Manufacturers should note that in future the tuning range for the ground transceivers may also cover any 25 kHz
channel from 108,000 MHz to 111,975 MHz.
The scope of the present document is limited to ground stations. The equivalent specification for airborne stations is
ETSI EN 302 842 [i.1].
A description of the scope of the VDL Mode 4 system is provided in part 2 of these technical specifications
(see ETSI EN 301 842-2 [5], clause 1).
ETSI EN 301 842-1 [4] deals with tests of the physical layer, ETSI EN 301 842-2 [5] deals with core link layer
functionality and ETSI EN 301 842-3 [6] with additional broadcast functionality. The present document deals with tests
of the datalink service (DLS) layer and the link layer sufficient to support point-to-point functionality.
The present document is organized as follows:
• clause 2 provides references to relevant documents;
• clause 3 provides general definitions, abbreviations and symbols used;
• clause 4 describes the VDL Mode 4 ground station point-to-point functions;
• clause 5 provides performance specifications for the VDL Mode 4 ground station;
• clause 6 provides general design requirements;
• clause 7 provides protocol tests for the point-to-point functions of the system;
• annex A provides a detailed cross-reference to the relevant requirements contained in [1];
• annex B provides a Bibliography.
Note that the system can support a very wide range of functions. It is not practical to provide specific tests for all
aspects of functionality. The approach used is to provide detailed tests for the core point-to-point functionality and
to provide tests of those remaining requirements which, if wrongly implemented, could cause a deterioration in the
service offered by other VDL Mode 4 stations.
ETSI
9 Draft ETSI EN 301 842-4 V1.3.0 (2014-12)
Mandating and Recommendation Phrases
a) "Shall":
- the use of the word "Shall" indicates a mandated criterion; i.e. compliance with the particular procedure
or specification is mandatory and no alternative may be applied.
b) "Should":
- the use of the word "Should" (and phrases such as "It is recommended that.", etc.) indicates that though
the procedure or criterion is regarded as the preferred option, alternative procedures, specifications or
criteria may be applied, provided that the manufacturer, installer or tester can provide information or data
to adequately support and justify the alternative.
2 References
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
referenced document (including any amendments) applies.
Referenced documents which are not found to be publicly available in the expected location might be found at
http://docbox.etsi.org/Reference.
NOTE: While any hyperlinks included in this clause were valid at the time of publication ETSI cannot guarantee
their long term validity.
2.1 Normative references
The following referenced documents are necessary for the application of the present document.
[1] ICAO Doc 9816 AN/448 (First Edition 2004): "Manual on VHF Digital Link (VDL) Mode 4,
Part 2: Detailed Technical Specifications".
[2] Void.
[3] ICAO Doc 9705/AN-956 (Edition 3.0 - 2002): "Manual of Technical Provisions for Aeronautical
Telecommunication Network (ATN)".
[4] ETSI EN 301 842-1 (V1.4.0): "VHF air-ground Digital Link (VDL) Mode 4 radio equipment;
Technical characteristics and methods of measurement for ground-based equipment; Part 1: EN for
ground equipment".
[5] ETSI EN 301 842-2 (V1.7.0): "VHF air-ground Digital Link (VDL) Mode 4 radio equipment;
Technical characteristics and methods of measurement for ground-based equipment;
Part 2: General description and data link layer".
[6] ETSI EN 301 842-3 (V1.4.0): "VHF air-ground Digital Link (VDL) Mode 4 radio equipment;
Technical characteristics and methods of measurement for ground-based equipment;
Part 3: Additional broadcast aspects".
[7] ICAO Annex 10 to the Convention on International Civil Aviation: "Aeronautical
Telecommunications, Volume III: Communication Systems, Part I: Digital Data Communication
Systems, chapter 6", including Amendment 88 (applicable 14/11/13).
ETSI
10 Draft ETSI EN 301 842-4 V1.3.0 (2014-12)
2.2 Informative references
The following referenced documents are not necessary for the application of the present document but they assist the
user with regard to a particular subject area.
[i.1] ETSI EN 302 842 (all parts): "VHF air-ground and air-air Digital Link (VDL) Mode 4 radio
equipment; Technical characteristics and methods of measurement for aeronautical mobile
(airborne) equipment".
3 Definitions and abbreviations
3.1 Definitions
3.1.1 Basic reference model definitions
See ETSI EN 301 842-2 [5], clause 3.1.1.
3.1.2 Service conventions definitions
See ETSI EN 301 842-2 [5], clause 3.1.2.
3.1.3 General definitions
For the purposes of the present document, the terms and definitions given in ETSI EN 301 842-1 [4], clause 3.1.3,
ETSI EN 301 842-2 [5], clause 3.1.3 and the following apply:
long transmission procedure: procedure that allows transfer of DATA packets in reserved slots, avoiding the loss rates
and delays associated with random access
NOTE: This includes the ability to link sequences of DATA packets, providing continuous transfer in reserved
slots.
More bit (M): bit that controls message fragmentation and concatenation
NOTE: It is set to zero to indicate the end of a message. It is set to 1 to indicate that it is part of a fragmented
message and that there are more fragments to follow.
Network Setup Connection Oriented Protocol (NSCOP): protocol that enables a ground-air link between mobiles
priority (pr): priority of a message, or, in the case of an RTS, the priority of the requested data
short transmission procedure: procedure for the sending of a single data packet
NOTE: It contains a reservation for a subsequent acknowledgement.
Toggle bit (T): bit that allows detection and rejection of duplicate DLPDUs
NOTE: The T bit is alternately set to 1 and 0 on each successive DATA transmission, except for retransmissions.
Zero-Overhead Connection-Orientated Protocol (ZOCOP): protocol that enables an air-air link between mobiles
3.1.4 Definition of bit order
In the tables included in the present document to illustrate the format of bursts, the following order is implied:
a) bit order in each burst subfield is indicated by subscript numbers. Bit 1 indicates the least significant bit; and
b) bits are transmitted octet by octet, starting with the first octet in each table, and within each octet the rightmost
bit (as shown in the tables) is transmitted first.
ETSI
11 Draft ETSI EN 301 842-4 V1.3.0 (2014-12)
3.2 Abbreviations
For the purposes of the present document, the following abbreviations apply:
A/G Air/Ground
ACK ACKnowledgement (burst)
ADM ADMinistration identifier
ADS-B Automatic Dependent Surveillance-Broadcast
ARS Administration Region Selector
ATN Aeronautical Telecommunication Network
CPR Compact Position Reporting
CRC Cyclic Redundancy Code
CTRL ConTRoL (DLPDU)
CTS Clear To Send (burst)
DLE Data Link Entity
DLPDU Data Link Protocol Data Unit
DLS Data Link Service
DM Disconnected Mode (DLPDU)
FRMR FRaMe Reject (DLPDU)
GFSK Gaussian filtered Frequency Shift Keying
GSC Global Signalling Channel
GSIF Ground Station Information Frame
hex hexadecimal
IA-5 International Alphabet 5
IB Initialize Bit
ICAO International Civil Aviation Organization
ID IDentity
INFO INFOrmation (DLPDU)
ISO International Organization for Standardization
IS-SME Intermediate System - System Management Entity
LCR Link Connection Refused
lg length
LME Link Management Entity
M More bit
MAC Media Access Control
MOPS Minimum Operational Performance Specification
NACK Negative ACKnowledgment
NETs Network Entity Titles
NM Nautical Mile
NSCOP Network Setup Connection Orientated Protocol
p priority
PCO Point of Control and Observation
PI Parameter Identifier
R&TTE Radio equipment and Telecommunications Terminal Equipment
RF Radio Frequency
RTS Request To Send (DLPDU)
SARPs Standards And Recommended Practices
SNDCF SubNetwork Dependant Convergence Function
SZOM Start Zero Overhead Mode (DLPDU)
T Toggle bit
UCTRL Unacknowledged ConTRoL data broadcast (DLPDU)
UDATA Unacknowledged DATA broadcast (DLPDU)
UINFO Unacknowledged user INFOrmation data broadcast (DLPDU)
VDL VHF Digital Link
VHF Very High Frequency
VME VDL Management Entity
VSS VDL Mode 4 Specific Services
ZOCOP Zero Overhead Connection-Orientated Protocol
ETSI
12 Draft ETSI EN 301 842-4 V1.3.0 (2014-12)
4 General description of VDL Mode 4 ground station
point-to-point services
4.1 General
A description of VDL Mode 4 is provided in ETSI EN 301 842-2 [5]. This clause provides a description of the datalink
layer and associated services of the VSS and LME required to support point-to-point communications.
The specifications in the present document provide air-to-ground and air-to-air point-to-point services based on the
ICAO Technical Manual. The present document includes:
• Point-to-point data and control data transfer functions from the DLS.
• Point-to-point link control within the LME.
Note that the present document covers the establishment, termination and handover of links between ground stations.
Decisions to establish, terminate or handover links between ground stations are local issues and beyond the scope of
these specifications.
In most respects, the VDL Mode 4 ground station follows the provisions of the ICAO standards material for VDL
Mode 4. Within the ICAO standard, there are some requirements which apply explicitly only to airborne stations.
Requirements on airborne stations are covered in ETSI EN 302 842 [i.1] Parts 1 to 4.
The scope of the present document is for a ground station supporting point-to-point applications. Hence the ability to
support broadcast communication is not included in the present document.
Note that, although certain protocols will not be used by the ground station, the ability to recognize the use by mobiles
of these protocols and to respond in a consistent manner is a ground station requirement and is included in the present
document.
4.2 Data Link Service (DLS) and Link Management Entity
(LME)
4.2.1 General
The Data Link Service (DLS) provides a point-to-point protocol supporting both air-to-ground and air-to-air exchanges.
For air-to-ground exchanges, connection management is handled by the LME, using a Negotiated Setup
Connection-Orientated Protocol (NSCOP). For air-to-air exchanges, the DLS defines a ZOCOP protocol with link
establishment and disestablishment controlled by timers, allowing rapid link negotiation between aircraft.
The specifications in the present document assume that VDL Mode 4 will be used with a network based on ATN
protocols [3]. It should be noted that, in future, it could support other network protocols.
The DLS is a simple information exchange protocol which provides:
a) Explicit acknowledgement of each DATA packet.
b) Mechanisms to provide data transfer in reserved slots, avoiding loss rates and delays associated with random
access. This includes the ability to link sequences of DATA packets, providing continuous transfer in reserved
slots.
c) Packet fragmentation, to allow long user data packets to be transferred across the link in fragments optimally
matched to the link conditions.
d) Duplicate detection and suppression via a simple toggle-bit mechanism.
e) Explicit support for the 15 priority levels defined for the ATN, including the ability for high priority messages
to be sent in the middle of a fragmented low priority message.
ETSI
13 Draft ETSI EN 301 842-4 V1.3.0 (2014-12)
As illustrated in figure 4.1, the DLS:
• Provides services to external users in order to support point-to-point, multi-cast and broadcast
communications.
• Provides services to the LME to support link management.
• Supports services between peer DLSs.
• Uses the services of the VSS in order to send and receive messages.
DLS User
LME
DLS
Peer DLS
VSS
Figure 4.1: Functions of the DLS
Figure 4.2 illustrates the use of various services provided by the DLS and VSS in supporting the DLS User and the
LME.
DLS User LME
Directed Data (INFO, CTRL) Broadcast Data (UDATA)
Connection Management (IB/SZOM)
Message Segmentation (M-bit)
Delivery Order (T-bit)
DLS
Long Short Long Short
Acknowledged Acknowledged Unacknowledged Unacknowledged
Information
Unicast
Transfer
Reservation
VSS
Reservation
Response Reservation
General Response Protocol (General Failure)
Burst Retransmission
Figure 4.2: Services provided by the DLS and VSS in support of DLS User and LME
ETSI
14 Draft ETSI EN 301 842-4 V1.3.0 (2014-12)
Protocols for short unacknowledged broadcast data have already been specified in the core link layer functionality
(ETSI EN 301 842-2 [5]).
A DLS Burst consists of:
• Burst ID (fixed or variable).
• One or two DLPDUs.
The following DATA DLPDUs (Data Link Protocol Data Units) are defined:
• CTRL - Used by the LME to establish and maintain links for NSCOP communication.
• INFO - Contains a user data field.
• UDATA - Either a UCTRL or a UINFO. Enables the broadcast of user data - it is unacknowledged.
The following RTS DLPDUs are defined:
• CTRL_RTS - Sent to request the sending of link maintenance data.
• INFO_RTS - A request to send user data (for long transmission procedures).
• UDATA_RTS - A request to send broadcast data.
The following ACK, CTS and other DLS link control DLPDUs are defined:
• UDATA_CTS - This DLPDU is a clear to send in response to a UDATA_RTS.
• INFO_ACK - An acknowledgement of the previous INFO DLPDU.
• INFO_CTS - A clear to send (for long transmission procedures).
• CTRL_ACK - An acknowledgement of the previous CTRL DLPDU.
• FRMR - Used to reset the link.
• FRMR_ACK - Sent to acknowledge receipt of FRMR.
• DM/DISC (Disconnected Mode) - Used to indicate that a DLS DLPDU has been received when no link has
been initialized.
• DM/FRMR - Used to indicate that a DLS DLPDU has been received when the link is in the process of being
initialized.
• SZOM - Sent in combination with an INFO, INFO_RTS or INFO_ACK to establish a link for ZOCOP
communication.
ETSI
15 Draft ETSI EN 301 842-4 V1.3.0 (2014-12)
The following table shows the DLS burst types.
Toggle More Bit Priority Negotiation Initialize Length
Bit (T) (M) (p) subfield (neg) bit IB (lg)
CTRL
INFO
UDATA
CTRL_RTS
INFO_RTS
UDATA_RTS
UDATA_CTS
INFO_ACK
CTRL_ACK
CTRL_CTS
FRMR_ACK
FRMR
DM/DISC
DM/FRMR
SZOM
Where:
• Toggle bit (T): This is used for duplicate detection and rejection.
• More bit (M): This is set to zero to indicate the end of a message. It is set to 1 to indicate that it is part of a
fragmented message and that there are more fragments to follow.
• Priority (p): This is the priority of the message.
• Negotiation subfield (neg): This indicates the link management parameters to be used for air-to-air link
control.
• Initialize Bit (IB): This bit causes the receiver to initialize the T and T state variables and to clear the send
t r
and receive arrays whilst processing the burst. It is set to zero and ignored on receipt unless otherwise stated.
• Length (lg): This is the length of the data message in slots.
4.2.2 DLS timers
The following timers are used in the DLS procedures:
• TD1: ZOCOP link transmit timer. This timer is reset when a burst is sent to the peer. If it expires, then T is set
t
to 0 and the send channel array cleared.
• TD2: ZOCOP link receive reset timer. This timer is reset when a burst is received from the peer. If this timer
expires then T is set to 0, the send channel array is cleared and the link is considered to be terminated.
t
4.2.3 DLS counters
The following counters are used in the DLS procedures:
• ND1: Maximum number of octets that may be submitted to the DLS for transfer.
• ND2: Maximum length of a DLS transmission that may use the short transmission procedures.
• ND3: Maximum length of a fragment in slots with M-bit processing.
• ND4: Maximum length of UDATA burst.
ETSI
16 Draft ETSI EN 301 842-4 V1.3.0 (2014-12)
4.2.4 Toggle bit (T)
The T (Toggle) bit allows detection and rejection of duplicate DLPDUs. The T bit is alternately set to 1 and 0 on each
successive DATA transmission, except for retransmissions. The associated RTS, CTS and ACK DLPDUs should have
the same value T bit as the DATA packet.
AB
DATA T = 1
ACK T = 1
DATA T = 0
ACK T = 0
Figure 4.3: Use of the T bit in a short procedure
4.2.5 State variables (T and T)
t r
When a message being transmitted is not the first message between the two stations, the sending station sets the T bit to
the inverse value that it had for the previous message. The value it transmitted previously is stored in the state
.
variable T
t
The receiving station compares the value of the T bit it receives with the value it received previously, to check that t
...
EUROPEAN STANDARD
VHF air-ground Digital Link (VDL) Mode 4 radio equipment;
Technical characteristics and methods of measurement
for ground-based equipment;
Part 4: Point-to-point functions
2 ETSI EN 301 842-4 V1.3.1 (2015-04)
Reference
REN/AERO-00020-4
Keywords
aeronautical, digital, radio, testing, VHF
ETSI
650 Route des Lucioles
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Tel.: +33 4 92 94 42 00 Fax: +33 4 93 65 47 16
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Sous-Préfecture de Grasse (06) N° 7803/88
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ETSI
3 ETSI EN 301 842-4 V1.3.1 (2015-04)
Contents
Intellectual Property Rights . 6
Foreword . 6
Modal verbs terminology . 6
Introduction . 7
1 Scope . 8
2 References . 9
2.1 Normative references . 9
2.2 Informative references . 9
3 Definitions and abbreviations . 10
3.1 Definitions . 10
3.1.1 Basic reference model definitions . 10
3.1.2 Service conventions definitions . 10
3.1.3 General definitio ns . 10
3.1.4 Definition of bit order . 10
3.2 Abbreviations . 10
4 General description of VDL Mode 4 ground station point-to-point services . 11
4.1 General . 11
4.2 Data Link Service (DLS) and Link Management Entity (LME) . 12
4.2.1 General . 12
4.2.2 DLS timers . 15
4.2.3 DLS counters . 15
4.2.4 Toggle bit (T) . 15
4.2.5 State variables (T and T ) . 16
t r
4.2.6 Initialize Bit (IB) . 16
4.2.7 More bit (M) . 16
4.2.8 Priority (pr) . 16
4.2.9 Message fragmentation and concatenation . 16
4.2.10 DLS procedures . 16
4.2.10.1 Selection of DLS procedures. 16
4.2.10.2 Short transmission procedures . 17
4.2.10.3 Long transmission procedures . 17
4.2.11 Linking transmissions . 19
4.2.11.1 Types of linking . 19
4.2.11.2 Combined RTS / DATA DLPDUs . 19
4.2.11.3 Combined DATA / ACK DLPDUs . 19
4.2.11.4 Combined RTS / ACK DLPDUs . 19
4.2.11.5 Combined CTS / ACK DLPDUs . 19
4.2.12 Ground-air link management . 19
4.2.13 Air-air link management . 20
4.3 Additional VSS Services . 20
5 Minimum performance specification under standard test conditions . 20
5.1 DLS Sublayer . 20
5.1.1 General . 20
5.1.1.1 Services . 20
5.1.1.2 Data transfer . 21
5.1.1.3 DATA DLPDU duplicate suppression and sequencing . 21
5.1.1.4 Error detection . 21
5.1.1.5 Station identification . 21
5.1.1.6 Broadcast addressing . 21
5.1.1.7 DLS Priority . 22
5.1.1.8 DLS Link control DLPDUs . 22
5.1.2 DLS protocol specification . 22
5.1.2.1 State Variables . 22
ETSI
4 ETSI EN 301 842-4 V1.3.1 (2015-04)
5.1.2.2 DLS burst formats . 22
5.1.3 DLS system parameters . 26
5.1.4 DLS procedures . 27
5.1.4.1 Setting of re-transmission parameter . 27
5.1.4.2 Selection of user data packet for transmission . 28
5.1.4.3 Selection of transmission procedures . 29
5.1.4.4 Short transmission procedures . 30
5.1.4.5 Long transmission procedures . 31
5.1.4.6 No link with sender . 33
5.1.4.7 User data packet reception . 34
5.1.4.8 Receipt of ACK DLPDU . 34
5.1.4.9 Link reset . 35
5.1.4.10 Linking DLS DLPDU transmissions . 35
5.1.4.11 CTRL DLPDU . 36
5.2 Link management entity sublayer. 36
5.2.1 Services . 36
5.2.1.1 General . 36
5.2.1.2 Link provision . 37
5.2.1.3 Link change notifications . 37
5.2.1.4 CTRL DLPDU . 37
5.2.1.5 Broadcast link management burst . 38
5.2.2 Control (CTRL) parameter formats . 38
5.2.2.1 Encoding . 38
5.2.2.2 General purpose information parameters . 38
5.2.2.3 Mobile-initiated information parameters . 42
5.2.2.4 Ground-initiated modification parameters . 43
5.2.2.5 Ground-initiated information parameters . 46
5.2.3 LME timers and parameters . 48
5.2.3.1 General . 48
5.2.3.2 Timer TL1 (maximum link overlap time) . 49
5.2.3.3 Parameters TL2 (link initialization time) . 49
5.2.3.4 Timer TL4 (leave generation latency) . 49
5.2.4 CTRL DLPDU types and procedures . 50
5.2.5 CTRL transmission procedures . 53
5.2.5.1 Link connectivity procedures . 53
5.2.5.2 Ground Station Identification . 53
5.2.5.3 Link establishment . 53
5.2.5.4 Mobile-initiated handoff . 54
5.2.5.5 Mobile-requested ground-initiated handoff . 54
5.2.5.6 Ground-initiated handoff . 55
5.2.5.7 Ground-requested mobile-initiated handoff . 55
5.2.5.8 Ground-requested broadcast handoff . 55
5.2.5.9 Ground-commanded autotune . 56
5.2.6 VDL Mode 4 Mobile Subnetwork Dependent Convergence Function (SNDCF) . 56
5.2.6.1 Frame Mode SNDCF . 56
5.3 Additional VSS Requirements . 56
5.3.1 Additional VSS quality of service parameters . 56
5.3.1.1 Parameter Q5 (VSS retransmission parameters) . 56
5.3.2 Unicast request protocol specification . 56
5.3.2.1 Unicast request parameters. 57
5.3.2.2 Unicast request transmission procedures . 58
5.3.3 Information transfer request protocol specification . 58
5.3.3.1 Information transfer request parameters . 58
5.3.3.2 Information transfer request transmission procedures . 60
5.3.3.3 Information transfer request acknowledgement procedures . 60
5.3.4 Retransmission procedures . 60
6 General design requirements . 61
7 Protocol test procedures . 61
7.1 General . 61
7.2 Required test rig . 61
ETSI
5 ETSI EN 301 842-4 V1.3.1 (2015-04)
7.3 Protocol test-suite description methodology . 61
7.4 Detailed protocol test procedures . 62
7.4.1 Test-suite overview . 62
7.4.2 Declarations . 64
7.4.3 Constraints . 64
7.4.3.1 Abbreviations . 64
7.4.3.1.1 Subfield mnemonics . 64
7.4.3.1.2 Special characters used in the subfield definitions . 65
7.4.3.1.3 Station addresses and positions . 65
7.4.3.1.4 VDL bursts . 66
7.4.3.2 Test cases . 96
7.4.3.2.1 Test case macros . 97
7.4.3.2.2 Test case descriptions . 99
Annex A (informative): Cross reference matrix . 154
Annex B (informative): Bibliography . 163
History . 164
ETSI
6 ETSI EN 301 842-4 V1.3.1 (2015-04)
Intellectual Property Rights
IPRs essential or potentially essential to the present document may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found
in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in
respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web
server (http://ipr.etsi.org).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee
can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web
server) which are, or may be, or may become, essential to the present document.
Foreword
This European Standard (EN) has been produced by ETSI Technical Committee Aeronautics (AERO).
The present document is part 4 of a multi-part deliverable covering the VHF air-ground Digital Link (VDL) Mode 4
radio equipment; Technical characteristics and methods of measurement for ground-based equipment, as identified
below:
Part 1: "EN for ground equipment";
Part 2: "General description and data link layer";
Part 3: "Additional broadcast aspects";
Part 4: "Point-to-point functions";
Part 5: "Hamonized EN covering the essential requirements of article 3.2 of the R&TTE Directive".
The present document is accompanied by an equivalent airborne standard, ETSI EN 302 842 [i.1] Parts 1 to 4, covering
the VHF air-ground Digital Link (VDL) Mode 4 radio equipment; Technical characteristics and methods of
measurement for airborne equipment.
National transposition dates
Date of adoption of this EN: 6 April 2015
Date of latest announcement of this EN (doa): 31 July 2015
Date of latest publication of new National Standard
or endorsement of this EN (dop/e): 31 January 2016
Date of withdrawal of any conflicting National Standard (dow): 31 January 2017
Modal verbs terminology
In the present document "shall", "shall not", "should", "should not", "may", "need not", "will", "will not", "can" and
"cannot" are to be interpreted as described in clause 3.2 of the ETSI Drafting Rules (Verbal forms for the expression of
provisions).
"must" and "must not" are NOT allowed in ETSI deliverables except when used in direct citation.
ETSI
7 ETSI EN 301 842-4 V1.3.1 (2015-04)
Introduction
The present document states the technical specifications for Very High Frequency (VHF) Digital Link (VDL) Mode 4
ground-based radio transmitters, transceivers and receivers for air-ground communications operating in the VHF band,
using Gaussian-filtered Frequency Shift Keying (GFSK) Modulation with 25 kHz channel spacing and capable of
tuning to any of the 25 kHz channels from 112,000 MHz to 136,975 MHz as defined in ICAO VHF Digital Link (VDL)
Standards and Recommended Practices (SARPs) [7].
The present document may be used to produce tests for the assessment of the performance of the equipment.
ETSI
8 ETSI EN 301 842-4 V1.3.1 (2015-04)
1 Scope
The present document applies to the following radio equipment types:
1) Very High Frequency (VHF) Digital Link (VDL) Mode 4 ground-based radio transmitters and receivers for
air-ground communications operating in the VHF band, using Gaussian-filtered Frequency Shift Keying (GFSK)
Modulation with 25 kHz channel spacing and capable of tuning to any of the 25 kHz channels from
112,000 MHz to 136,975 MHz as defined in ICAO VHF Digital Link (VDL) Standards and Recommended
Practices (SARPs) [7].
The present document provides part 4 of the technical specifications.
The present document is designed to ensure that equipment certified to it will be compatible with the relevant ICAO
VHF Digital Link (VDL) Standards and Recommended Practices (SARPs) [7] and VDL Mode 4 Technical Manual
(TM) [1].
Manufacturers should note that in future the tuning range for the ground transceivers may also cover any 25 kHz
channel from 108,000 MHz to 111,975 MHz.
The scope of the present document is limited to ground stations. The equivalent specification for airborne stations is
ETSI EN 302 842 [i.1].
A description of the scope of the VDL Mode 4 system is provided in part 2 of these technical specifications
(see ETSI EN 301 842-2 [5], clause 1).
ETSI EN 301 842-1 [4] deals with tests of the physical layer, ETSI EN 301 842-2 [5] deals with core link layer
functionality and ETSI EN 301 842-3 [6] with additional broadcast functionality. The present document deals with tests
of the datalink service (DLS) layer and the link layer sufficient to support point-to-point functionality.
The present document is organized as follows:
• clause 2 provides references to relevant documents;
• clause 3 provides general definitions, abbreviations and symbols used;
• clause 4 describes the VDL Mode 4 ground station point-to-point functions;
• clause 5 provides performance specifications for the VDL Mode 4 ground station;
• clause 6 provides general design requirements;
• clause 7 provides protocol tests for the point-to-point functions of the system;
• annex A provides a detailed cross-reference to the relevant requirements contained in [1];
• annex B provides a Bibliography.
Note that the system can support a very wide range of functions. It is not practical to provide specific tests for all
aspects of functionality. The approach used is to provide detailed tests for the core point-to-point functionality and
to provide tests of those remaining requirements which, if wrongly implemented, could cause a deterioration in the
service offered by other VDL Mode 4 stations.
Mandating and Recommendation Phrases
a) "Shall":
- the use of the word "Shall" indicates a mandated criterion; i.e. compliance with the particular procedure
or specification is mandatory and no alternative may be applied.
b) "Should":
- the use of the word "Should" (and phrases such as "It is recommended that.", etc.) indicates that though
the procedure or criterion is regarded as the preferred option, alternative procedures, specifications or
criteria may be applied, provided that the manufacturer, installer or tester can provide information or data
to adequately support and justify the alternative.
ETSI
9 ETSI EN 301 842-4 V1.3.1 (2015-04)
2 References
2.1 Normative references
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
referenced document (including any amendments) applies.
Referenced documents which are not found to be publicly available in the expected location might be found at
http://docbox.etsi.org/Reference.
NOTE: While any hyperlinks included in this clause were valid at the time of publication ETSI cannot guarantee
their long term validity.
The following referenced documents are necessary for the application of the present document.
[1] ICAO Doc 9816 AN/448 (First Edition 2004): "Manual on VHF Digital Link (VDL) Mode 4,
Part 2: Detailed Technical Specifications".
[2] Void.
[3] ICAO Doc 9705/AN-956 (Edition 3.0 - 2002): "Manual of Technical Provisions for Aeronautical
Telecommunication Network (ATN)".
[4] ETSI EN 301 842-1 (V1.4.1): "VHF air-ground Digital Link (VDL) Mode 4 radio equipment;
Technical characteristics and methods of measurement for ground-based equipment; Part 1: EN for
ground equipment".
[5] ETSI EN 301 842-2 (V1.7.1): "VHF air-ground Digital Link (VDL) Mode 4 radio equipment;
Technical characteristics and methods of measurement for ground-based equipment;
Part 2: General description and data link layer".
[6] ETSI EN 301 842-3 (V1.4.1): "VHF air-ground Digital Link (VDL) Mode 4 radio equipment;
Technical characteristics and methods of measurement for ground-based equipment;
Part 3: Additional broadcast aspects".
[7] ICAO Annex 10 to the Convention on International Civil Aviation: "Aeronautical
Telecommunications, Volume III: Communication Systems, Part I: Digital Data Communication
Systems, chapter 6", including Amendment 88 (applicable 14/11/13).
2.2 Informative references
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
referenced document (including any amendments) applies.
NOTE: While any hyperlinks included in this clause were valid at the time of publication ETSI cannot guarantee
their long term validity.
The following referenced documents are not necessary for the application of the present document but they assist the
user with regard to a particular subject area.
[i.1] ETSI EN 302 842 (all parts): "VHF air-ground and air-air Digital Link (VDL) Mode 4 radio
equipment; Technical characteristics and methods of measurement for aeronautical mobile
(airborne) equipment".
ETSI
10 ETSI EN 301 842-4 V1.3.1 (2015-04)
3 Definitions and abbreviations
3.1 Definitions
3.1.1 Basic reference model definitions
See ETSI EN 301 842-2 [5], clause 3.1.1.
3.1.2 Service conventions definitions
See ETSI EN 301 842-2 [5], clause 3.1.2.
3.1.3 General definitions
For the purposes of the present document, the terms and definitions given in ETSI EN 301 842-1 [4], clause 3.1.3,
ETSI EN 301 842-2 [5], clause 3.1.3 and the following apply:
long transmission procedure: procedure that allows transfer of DATA packets in reserved slots, avoiding the loss rates
and delays associated with random access
NOTE: This includes the ability to link sequences of DATA packets, providing continuous transfer in reserved
slots.
More bit (M): bit that controls message fragmentation and concatenation
NOTE: It is set to zero to indicate the end of a message. It is set to 1 to indicate that it is part of a fragmented
message and that there are more fragments to follow.
Network Setup Connection Oriented Protocol (NSCOP): protocol that enables a ground-air link between mobiles
priority (pr): priority of a message, or, in the case of an RTS, the priority of the requested data
short transmission procedure: procedure for the sending of a single data packet
NOTE: It contains a reservation for a subsequent acknowledgement.
Toggle bit (T): bit that allows detection and rejection of duplicate DLPDUs
NOTE: The T bit is alternately set to 1 and 0 on each successive DATA transmission, except for retransmissions.
Zero-Overhead Connection-Orientated Protocol (ZOCOP): protocol that enables an air-air link between mobiles
3.1.4 Definition of bit order
In the tables included in the present document to illustrate the format of bursts, the following order is implied:
a) bit order in each burst subfield is indicated by subscript numbers. Bit 1 indicates the least significant bit; and
b) bits are transmitted octet by octet, starting with the first octet in each table, and within each octet the rightmost
bit (as shown in the tables) is transmitted first.
3.2 Abbreviations
For the purposes of the present document, the following abbreviations apply:
A/G Air/Ground
ACK ACKnowledgement (burst)
ADM ADMinistration identifier
ADS-B Automatic Dependent Surveillance-Broadcast
ARS Administration Region Selector
ATN Aeronautical Telecommunication Network
CPR Compact Position Reporting
CRC Cyclic Redundancy Code
ETSI
11 ETSI EN 301 842-4 V1.3.1 (2015-04)
CTRL ConTRoL (DLPDU)
CTS Clear To Send (burst)
DLE Data Link Entity
DLPDU Data Link Protocol Data Unit
DLS Data Link Service
DM Disconnected Mode (DLPDU)
FRMR FRaMe Reject (DLPDU)
GFSK Gaussian filtered Frequency Shift Keying
GSC Global Signalling Channel
GSIF Ground Station Information Frame
hex hexadecimal
IA-5 International Alphabet 5
IB Initialize Bit
ICAO International Civil Aviation Organization
ID IDentity
INFO INFOrmation (DLPDU)
ISO International Organization for Standardization
IS-SME Intermediate System - System Management Entity
LCR Link Connection Refused
lg length
LME Link Management Entity
M More bit
MAC Media Access Control
MOPS Minimum Operational Performance Specification
NACK Negative ACKnowledgment
NETs Network Entity Titles
NM Nautical Mile
NSCOP Network Setup Connection Orientated Protocol
p priority
PCO Point of Control and Observation
PI Parameter Identifier
R&TTE Radio equipment and Telecommunications Terminal Equipment
RF Radio Frequency
RTS Request To Send (DLPDU)
SARPs Standards And Recommended Practices
SNDCF SubNetwork Dependant Convergence Function
SZOM Start Zero Overhead Mode (DLPDU)
T Toggle bit
UCTRL Unacknowledged ConTRoL data broadcast (DLPDU)
UDATA Unacknowledged DATA broadcast (DLPDU)
UINFO Unacknowledged user INFOrmation data broadcast (DLPDU)
VDL VHF Digital Link
VHF Very High Frequency
VME VDL Management Entity
VSS VDL Mode 4 Specific Services
ZOCOP Zero Overhead Connection-Orientated Protocol
4 General description of VDL Mode 4 ground station
point-to-point services
4.1 General
A description of VDL Mode 4 is provided in ETSI EN 301 842-2 [5]. This clause provides a description of the datalink
layer and associated services of the VSS and LME required to support point-to-point communications.
The specifications in the present document provide air-to-ground and air-to-air point-to-point services based on the
ICAO Technical Manual. The present document includes:
• Point-to-point data and control data transfer functions from the DLS.
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12 ETSI EN 301 842-4 V1.3.1 (2015-04)
• Point-to-point link control within the LME.
Note that the present document covers the establishment, termination and handover of links between ground stations.
Decisions to establish, terminate or handover links between ground stations are local issues and beyond the scope of
these specifications.
In most respects, the VDL Mode 4 ground station follows the provisions of the ICAO standards material for VDL
Mode 4. Within the ICAO standard, there are some requirements which apply explicitly only to airborne stations.
Requirements on airborne stations are covered in ETSI EN 302 842 [i.1] Parts 1 to 4.
The scope of the present document is for a ground station supporting point-to-point applications. Hence the ability to
support broadcast communication is not included in the present document.
Note that, although certain protocols will not be used by the ground station, the ability to recognize the use by mobiles
of these protocols and to respond in a consistent manner is a ground station requirement and is included in the present
document.
4.2 Data Link Service (DLS) and Link Management Entity
(LME)
4.2.1 General
The Data Link Service (DLS) provides a point-to-point protocol supporting both air-to-ground and air-to-air exchanges.
For air-to-ground exchanges, connection management is handled by the LME, using a Negotiated Setup
Connection-Orientated Protocol (NSCOP). For air-to-air exchanges, the DLS defines a ZOCOP protocol with link
establishment and disestablishment controlled by timers, allowing rapid link negotiation between aircraft.
The specifications in the present document assume that VDL Mode 4 will be used with a network based on ATN
protocols [3]. It should be noted that, in future, it could support other network protocols.
The DLS is a simple information exchange protocol which provides:
a) Explicit acknowledgement of each DATA packet.
b) Mechanisms to provide data transfer in reserved slots, avoiding loss rates and delays associated with random
access. This includes the ability to link sequences of DATA packets, providing continuous transfer in reserved
slots.
c) Packet fragmentation, to allow long user data packets to be transferred across the link in fragments optimally
matched to the link conditions.
d) Duplicate detection and suppression via a simple toggle-bit mechanism.
e) Explicit support for the 15 priority levels defined for the ATN, including the ability for high priority messages
to be sent in the middle of a fragmented low priority message.
As illustrated in figure 4.1, the DLS:
• Provides services to external users in order to support point-to-point, multi-cast and broadcast
communications.
• Provides services to the LME to support link management.
• Supports services between peer DLSs.
• Uses the services of the VSS in order to send and receive messages.
ETSI
13 ETSI EN 301 842-4 V1.3.1 (2015-04)
DLS User
LME
DLS
Peer DLS
VSS
Figure 4.1: Functions of the DLS
Figure 4.2 illustrates the use of various services provided by the DLS and VSS in supporting the DLS User and the
LME.
DLS User LME
Directed Data (INFO, CTRL) Broadcast Data (UDATA)
Connection Management (IB/SZOM)
Message Segmentation (M-bit)
Delivery Order (T-bit)
DLS
Long Short Long Short
Acknowledged Acknowledged Unacknowledged Unacknowledged
Information
Unicast
Transfer
Reservation
VSS
Reservation
Response Reservation
General Response Protocol (General Failure)
Burst Retransmission
Figure 4.2: Services provided by the DLS and VSS in support of DLS User and LME
Protocols for short unacknowledged broadcast data have already been specified in the core link layer functionality
(ETSI EN 301 842-2 [5]).
A DLS Burst consists of:
• Burst ID (fixed or variable).
• One or two DLPDUs.
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14 ETSI EN 301 842-4 V1.3.1 (2015-04)
The following DATA DLPDUs (Data Link Protocol Data Units) are defined:
• CTRL - Used by the LME to establish and maintain links for NSCOP communication.
• INFO - Contains a user data field.
• UDATA - Either a UCTRL or a UINFO. Enables the broadcast of user data - it is unacknowledged.
The following RTS DLPDUs are defined:
• CTRL_RTS - Sent to request the sending of link maintenance data.
• INFO_RTS - A request to send user data (for long transmission procedures).
• UDATA_RTS - A request to send broadcast data.
The following ACK, CTS and other DLS link control DLPDUs are defined:
• UDATA_CTS - This DLPDU is a clear to send in response to a UDATA_RTS.
• INFO_ACK - An acknowledgement of the previous INFO DLPDU.
• INFO_CTS - A clear to send (for long transmission procedures).
• CTRL_ACK - An acknowledgement of the previous CTRL DLPDU.
• FRMR - Used to reset the link.
• FRMR_ACK - Sent to acknowledge receipt of FRMR.
• DM/DISC (Disconnected Mode) - Used to indicate that a DLS DLPDU has been received when no link has
been initialized.
• DM/FRMR - Used to indicate that a DLS DLPDU has been received when the link is in the process of being
initialized.
• SZOM - Sent in combination with an INFO, INFO_RTS or INFO_ACK to establish a link for ZOCOP
communication.
The following table shows the DLS burst types.
Toggle More Bit Priority Negotiation Initialize Length
Bit (T) (M) (p) subfield (neg) bit IB (lg)
CTRL
INFO
UDATA
CTRL_RTS
INFO_RTS
UDATA_RTS
UDATA_CTS
INFO_ACK
CTRL_ACK
CTRL_CTS
FRMR_ACK
FRMR
DM/DISC
DM/FRMR
SZOM
Where:
• Toggle bit (T): This is used for duplicate detection and rejection.
• More bit (M): This is set to zero to indicate the end of a message. It is set to 1 to indicate that it is part of a
fragmented message and that there are more fragments to follow.
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15 ETSI EN 301 842-4 V1.3.1 (2015-04)
• Priority (p): This is the priority of the message.
• Negotiation subfield (neg): This indicates the link management parameters to be used for air-to-air link
control.
• Initialize Bit (IB): This bit causes the receiver to initialize the T and T state variables and to clear the send
t r
and receive arrays whilst processing the burst. It is set to zero and ignored on receipt unless otherwise stated.
• Length (lg): This is the length of the data message in slots.
4.2.2 DLS timers
The following timers are used in the DLS procedures:
• TD1: ZOCOP link transmit timer. This timer is reset when a burst is sent to the peer. If it expires, then T is set
t
to 0 and the send channel array cleared.
• TD2: ZOCOP link receive reset timer. This timer is reset when a burst is received from the peer. If this timer
expires then T is set to 0, the send channel array is cleared and the link is considered to be terminated.
t
4.2.3 DLS counters
The following counters are used in the DLS procedures:
• ND1: Maximum number of octets that may be submitted to the DLS for transfer.
• ND2: Maximum length of a DLS transmission that may use the short transmission procedures.
• ND3: Maximum length of a fragment in slots with M-bit processing.
• ND4: Maximum length of UDATA burst.
4.2.4 Toggle bit (T)
The T (Toggle) bit allows detection and rejection of duplicate DLPDUs. The T bit is alternately set to 1 and 0 on each
successive DATA transmission, except for retransmissions. The associated RTS, CTS and ACK DLPDUs should have
the same value T bit as the DATA packet.
AB
DATA T = 1
ACK T = 1
DATA T = 0
ACK T = 0
Figure 4.3: Use of the T bit in a short procedure
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16 ETSI EN 301 842-4 V1.3.1 (2015-04)
4.2.5 State variables (T and T)
t r
When a message being transmitted is not the first message between the two stations, the sending station sets the
...
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.KQLþQHWRþNDVHF air-ground Digital Link (VDL) Mode 4 radio equipment; Technical characteristics and methods of measurement for ground-based equipment; Part 4: Point-to-point functions49.090On-board equipment and instruments33.060.99Druga oprema za radijske komunikacijeOther equipment for radiocommunicationsICS:Ta slovenski standard je istoveten z:EN 301 842-4 V1.3.1SIST EN 301 842-4 V1.3.1:2015en,fr,de01-oktober-2015SIST EN 301 842-4 V1.3.1:2015SLOVENSKI
STANDARD
EUROPEAN STANDARD SIST EN 301 842-4 V1.3.1:2015
ETSI ETSI EN 301 842-4 V1.3.1 (2015-04) 2
Reference REN/AERO-00020-4 Keywords aeronautical, digital, radio, testing, VHF ETSI 650 Route des Lucioles F-06921 Sophia Antipolis Cedex - FRANCE
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DECTTM, PLUGTESTSTM, UMTSTM and the ETSI logo are Trade Marks of ETSI registered for the benefit of its Members. 3GPPTM and LTE™ are Trade Marks of ETSI registered for the benefit of its Members and of the 3GPP Organizational Partners. GSM® and the GSM logo are Trade Marks registered and owned by the GSM Association. SIST EN 301 842-4 V1.3.1:2015
ETSI ETSI EN 301 842-4 V1.3.1 (2015-04) 3 Contents Intellectual Property Rights . 6 Foreword . 6 Modal verbs terminology . 6 Introduction . 7 1 Scope . 8 2 References . 9 2.1 Normative references . 9 2.2 Informative references . 9 3 Definitions and abbreviations . 10 3.1 Definitions . 10 3.1.1 Basic reference model definitions . 10 3.1.2 Service conventions definitions . 10 3.1.3 General definitions . 10 3.1.4 Definition of bit order . 10 3.2 Abbreviations . 10 4 General description of VDL Mode 4 ground station point-to-point services . 11 4.1 General . 11 4.2 Data Link Service (DLS) and Link Management Entity (LME) . 12 4.2.1 General . 12 4.2.2 DLS timers . 15 4.2.3 DLS counters . 15 4.2.4 Toggle bit (T) . 15 4.2.5 State variables (Tt and Tr) . 16 4.2.6 Initialize Bit (IB) . 16 4.2.7 More bit (M) . 16 4.2.8 Priority (pr) . 16 4.2.9 Message fragmentation and concatenation . 16 4.2.10 DLS procedures . 16 4.2.10.1 Selection of DLS procedures. 16 4.2.10.2 Short transmission procedures . 17 4.2.10.3 Long transmission procedures . 17 4.2.11 Linking transmissions . 19 4.2.11.1 Types of linking . 19 4.2.11.2 Combined RTS / DATA DLPDUs . 19 4.2.11.3 Combined DATA / ACK DLPDUs . 19 4.2.11.4 Combined RTS / ACK DLPDUs . 19 4.2.11.5 Combined CTS / ACK DLPDUs . 19 4.2.12 Ground-air link management . 19 4.2.13 Air-air link management . 20 4.3 Additional VSS Services . 20 5 Minimum performance specification under standard test conditions . 20 5.1 DLS Sublayer . 20 5.1.1 General . 20 5.1.1.1 Services . 20 5.1.1.2 Data transfer . 21 5.1.1.3 DATA DLPDU duplicate suppression and sequencing . 21 5.1.1.4 Error detection . 21 5.1.1.5 Station identification . 21 5.1.1.6 Broadcast addressing . 21 5.1.1.7 DLS Priority . 22 5.1.1.8 DLS Link control DLPDUs . 22 5.1.2 DLS protocol specification . 22 5.1.2.1 State Variables . 22 SIST EN 301 842-4 V1.3.1:2015
ETSI ETSI EN 301 842-4 V1.3.1 (2015-04) 4 5.1.2.2 DLS burst formats . 22 5.1.3 DLS system parameters . 26 5.1.4 DLS procedures . 27 5.1.4.1 Setting of re-transmission parameter . 27 5.1.4.2 Selection of user data packet for transmission . 28 5.1.4.3 Selection of transmission procedures . 29 5.1.4.4 Short transmission procedures . 30 5.1.4.5 Long transmission procedures . 31 5.1.4.6 No link with sender . 33 5.1.4.7 User data packet reception . 34 5.1.4.8 Receipt of ACK DLPDU . 34 5.1.4.9 Link reset . 35 5.1.4.10 Linking DLS DLPDU transmissions . 35 5.1.4.11 CTRL DLPDU . 36 5.2 Link management entity sublayer. 36 5.2.1 Services . 36 5.2.1.1 General . 36 5.2.1.2 Link provision . 37 5.2.1.3 Link change notifications . 37 5.2.1.4 CTRL DLPDU . 37 5.2.1.5 Broadcast link management burst . 38 5.2.2 Control (CTRL) parameter formats . 38 5.2.2.1 Encoding . 38 5.2.2.2 General purpose information parameters . 38 5.2.2.3 Mobile-initiated information parameters . 42 5.2.2.4 Ground-initiated modification parameters . 43 5.2.2.5 Ground-initiated information parameters . 46 5.2.3 LME timers and parameters . 48 5.2.3.1 General . 48 5.2.3.2 Timer TL1 (maximum link overlap time) . 49 5.2.3.3 Parameters TL2 (link initialization time) . 49 5.2.3.4 Timer TL4 (leave generation latency) . 49 5.2.4 CTRL DLPDU types and procedures . 50 5.2.5 CTRL transmission procedures . 53 5.2.5.1 Link connectivity procedures . 53 5.2.5.2 Ground Station Identification . 53 5.2.5.3 Link establishment . 53 5.2.5.4 Mobile-initiated handoff . 54 5.2.5.5 Mobile-requested ground-initiated handoff . 54 5.2.5.6 Ground-initiated handoff . 55 5.2.5.7 Ground-requested mobile-initiated handoff . 55 5.2.5.8 Ground-requested broadcast handoff . 55 5.2.5.9 Ground-commanded autotune . 56 5.2.6 VDL Mode 4 Mobile Subnetwork Dependent Convergence Function (SNDCF) . 56 5.2.6.1 Frame Mode SNDCF . 56 5.3 Additional VSS Requirements . 56 5.3.1 Additional VSS quality of service parameters . 56 5.3.1.1 Parameter Q5 (VSS retransmission parameters) . 56 5.3.2 Unicast request protocol specification . 56 5.3.2.1 Unicast request parameters. 57 5.3.2.2 Unicast request transmission procedures . 58 5.3.3 Information transfer request protocol specification . 58 5.3.3.1 Information transfer request parameters . 58 5.3.3.2 Information transfer request transmission procedures . 60 5.3.3.3 Information transfer request acknowledgement procedures . 60 5.3.4 Retransmission procedures . 60 6 General design requirements . 61 7 Protocol test procedures . 61 7.1 General . 61 7.2 Required test rig . 61 SIST EN 301 842-4 V1.3.1:2015
ETSI ETSI EN 301 842-4 V1.3.1 (2015-04) 5 7.3 Protocol test-suite description methodology . 61 7.4 Detailed protocol test procedures . 62 7.4.1 Test-suite overview . 62 7.4.2 Declarations . 64 7.4.3 Constraints . 64 7.4.3.1 Abbreviations . 64 7.4.3.1.1 Subfield mnemonics . 64 7.4.3.1.2 Special characters used in the subfield definitions . 65 7.4.3.1.3 Station addresses and positions . 65 7.4.3.1.4 VDL bursts . 66 7.4.3.2 Test cases . 96 7.4.3.2.1 Test case macros . 97 7.4.3.2.2 Test case descriptions . 99 Annex A (informative): Cross reference matrix . 154 Annex B (informative): Bibliography . 163 History . 164
ETSI ETSI EN 301 842-4 V1.3.1 (2015-04) 6 Intellectual Property Rights IPRs essential or potentially essential to the present document may have been declared to ETSI. The information pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web server (http://ipr.etsi.org). Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web server) which are, or may be, or may become, essential to the present document. Foreword This European Standard (EN) has been produced by ETSI Technical Committee Aeronautics (AERO). The present document is part 4 of a multi-part deliverable covering the VHF air-ground Digital Link (VDL) Mode 4 radio equipment; Technical characteristics and methods of measurement for ground-based equipment, as identified below: Part 1: "EN for ground equipment"; Part 2: "General description and data link layer"; Part 3: "Additional broadcast aspects"; Part 4: "Point-to-point functions"; Part 5: "Hamonized EN covering the essential requirements of article 3.2 of the R&TTE Directive". The present document is accompanied by an equivalent airborne standard, ETSI EN 302 842 [i.1] Parts 1 to 4, covering the VHF air-ground Digital Link (VDL) Mode 4 radio equipment; Technical characteristics and methods of measurement for airborne equipment.
National transposition dates Date of adoption of this EN: 6 April 2015 Date of latest announcement of this EN (doa): 31 July 2015 Date of latest publication of new National Standard or endorsement of this EN (dop/e):
31 January 2016 Date of withdrawal of any conflicting National Standard (dow): 31 January 2017
Modal verbs terminology In the present document "shall", "shall not", "should", "should not", "may", "need not", "will", "will not", "can" and "cannot" are to be interpreted as described in clause 3.2 of the ETSI Drafting Rules (Verbal forms for the expression of provisions). "must" and "must not" are NOT allowed in ETSI deliverables except when used in direct citation. SIST EN 301 842-4 V1.3.1:2015
ETSI ETSI EN 301 842-4 V1.3.1 (2015-04) 7 Introduction The present document states the technical specifications for Very High Frequency (VHF) Digital Link (VDL) Mode 4 ground-based radio transmitters, transceivers and receivers for air-ground communications operating in the VHF band, using Gaussian-filtered Frequency Shift Keying (GFSK) Modulation with 25 kHz channel spacing and capable of tuning to any of the 25 kHz channels from 112,000 MHz to 136,975 MHz as defined in ICAO VHF Digital Link (VDL) Standards and Recommended Practices (SARPs) [7]. The present document may be used to produce tests for the assessment of the performance of the equipment.
ETSI ETSI EN 301 842-4 V1.3.1 (2015-04) 8 1 Scope The present document applies to the following radio equipment types: 1) Very High Frequency (VHF) Digital Link (VDL) Mode 4 ground-based radio transmitters and receivers for air-ground communications operating in the VHF band, using Gaussian-filtered Frequency Shift Keying (GFSK) Modulation with 25 kHz channel spacing and capable of tuning to any of the 25 kHz channels from 112,000 MHz to 136,975 MHz as defined in ICAO VHF Digital Link (VDL) Standards and Recommended Practices (SARPs) [7]. The present document provides part 4 of the technical specifications. The present document is designed to ensure that equipment certified to it will be compatible with the relevant ICAO VHF Digital Link (VDL) Standards and Recommended Practices (SARPs) [7] and VDL Mode 4 Technical Manual (TM) [1]. Manufacturers should note that in future the tuning range for the ground transceivers may also cover any 25 kHz channel from 108,000 MHz to 111,975 MHz. The scope of the present document is limited to ground stations. The equivalent specification for airborne stations is
ETSI EN 302 842 [i.1]. A description of the scope of the VDL Mode 4 system is provided in part 2 of these technical specifications (see ETSI EN 301 842-2 [5], clause 1). ETSI EN 301 842-1 [4] deals with tests of the physical layer, ETSI EN 301 842-2 [5] deals with core link layer functionality and ETSI EN 301 842-3 [6] with additional broadcast functionality. The present document deals with tests of the datalink service (DLS) layer and the link layer sufficient to support point-to-point functionality. The present document is organized as follows: • clause 2 provides references to relevant documents; • clause 3 provides general definitions, abbreviations and symbols used; • clause 4 describes the VDL Mode 4 ground station point-to-point functions; • clause 5 provides performance specifications for the VDL Mode 4 ground station; • clause 6 provides general design requirements; • clause 7 provides protocol tests for the point-to-point functions of the system; • annex A provides a detailed cross-reference to the relevant requirements contained in [1]; • annex B provides a Bibliography. Note that the system can support a very wide range of functions. It is not practical to provide specific tests for all aspects of functionality. The approach used is to provide detailed tests for the core point-to-point functionality and to provide tests of those remaining requirements which, if wrongly implemented, could cause a deterioration in the service offered by other VDL Mode 4 stations. Mandating and Recommendation Phrases a) "Shall": - the use of the word "Shall" indicates a mandated criterion; i.e. compliance with the particular procedure or specification is mandatory and no alternative may be applied. b) "Should": - the use of the word "Should" (and phrases such as "It is recommended that.", etc.) indicates that though the procedure or criterion is regarded as the preferred option, alternative procedures, specifications or criteria may be applied, provided that the manufacturer, installer or tester can provide information or data to adequately support and justify the alternative. SIST EN 301 842-4 V1.3.1:2015
ETSI ETSI EN 301 842-4 V1.3.1 (2015-04) 9 2 References 2.1 Normative references References are either specific (identified by date of publication and/or edition number or version number) or non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the referenced document (including any amendments) applies. Referenced documents which are not found to be publicly available in the expected location might be found at http://docbox.etsi.org/Reference. NOTE: While any hyperlinks included in this clause were valid at the time of publication ETSI cannot guarantee their long term validity. The following referenced documents are necessary for the application of the present document. [1] ICAO Doc 9816 AN/448 (First Edition 2004): "Manual on VHF Digital Link (VDL) Mode 4, Part 2: Detailed Technical Specifications". [2] Void. [3] ICAO Doc 9705/AN-956 (Edition 3.0 - 2002): "Manual of Technical Provisions for Aeronautical Telecommunication Network (ATN)". [4] ETSI EN 301 842-1 (V1.4.1): "VHF air-ground Digital Link (VDL) Mode 4 radio equipment; Technical characteristics and methods of measurement for ground-based equipment; Part 1: EN for ground equipment". [5] ETSI EN 301 842-2 (V1.7.1): "VHF air-ground Digital Link (VDL) Mode 4 radio equipment; Technical characteristics and methods of measurement for ground-based equipment; Part 2: General description and data link layer". [6] ETSI EN 301 842-3 (V1.4.1): "VHF air-ground Digital Link (VDL) Mode 4 radio equipment; Technical characteristics and methods of measurement for ground-based equipment; Part 3: Additional broadcast aspects". [7] ICAO Annex 10 to the Convention on International Civil Aviation: "Aeronautical Telecommunications, Volume III: Communication Systems, Part I: Digital Data Communication Systems, chapter 6", including Amendment 88 (applicable 14/11/13). 2.2 Informative references References are either specific (identified by date of publication and/or edition number or version number) or non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the referenced document (including any amendments) applies. NOTE: While any hyperlinks included in this clause were valid at the time of publication ETSI cannot guarantee their long term validity. The following referenced documents are not necessary for the application of the present document but they assist the user with regard to a particular subject area. [i.1] ETSI EN 302 842 (all parts): "VHF air-ground and air-air Digital Link (VDL) Mode 4 radio equipment; Technical characteristics and methods of measurement for aeronautical mobile (airborne) equipment". SIST EN 301 842-4 V1.3.1:2015
ETSI ETSI EN 301 842-4 V1.3.1 (2015-04) 10 3 Definitions and abbreviations 3.1 Definitions 3.1.1 Basic reference model definitions See ETSI EN 301 842-2 [5], clause 3.1.1. 3.1.2 Service conventions definitions See ETSI EN 301 842-2 [5], clause 3.1.2. 3.1.3 General definitions For the purposes of the present document, the terms and definitions given in ETSI EN 301 842-1 [4], clause 3.1.3, ETSI EN 301 842-2 [5], clause 3.1.3 and the following apply: long transmission procedure: procedure that allows transfer of DATA packets in reserved slots, avoiding the loss rates and delays associated with random access NOTE: This includes the ability to link sequences of DATA packets, providing continuous transfer in reserved slots. More bit (M): bit that controls message fragmentation and concatenation NOTE: It is set to zero to indicate the end of a message. It is set to 1 to indicate that it is part of a fragmented message and that there are more fragments to follow. Network Setup Connection Oriented Protocol (NSCOP): protocol that enables a ground-air link between mobiles priority (pr): priority of a message, or, in the case of an RTS, the priority of the requested data short transmission procedure: procedure for the sending of a single data packet NOTE: It contains a reservation for a subsequent acknowledgement. Toggle bit (T): bit that allows detection and rejection of duplicate DLPDUs NOTE: The T bit is alternately set to 1 and 0 on each successive DATA transmission, except for retransmissions. Zero-Overhead Connection-Orientated Protocol (ZOCOP): protocol that enables an air-air link between mobiles 3.1.4 Definition of bit order In the tables included in the present document to illustrate the format of bursts, the following order is implied: a) bit order in each burst subfield is indicated by subscript numbers. Bit 1 indicates the least significant bit; and b) bits are transmitted octet by octet, starting with the first octet in each table, and within each octet the rightmost bit (as shown in the tables) is transmitted first. 3.2 Abbreviations For the purposes of the present document, the following abbreviations apply: A/G Air/Ground ACK ACKnowledgement (burst) ADM ADMinistration identifier ADS-B Automatic Dependent Surveillance-Broadcast ARS Administration Region Selector ATN Aeronautical Telecommunication Network CPR Compact Position Reporting CRC Cyclic Redundancy Code SIST EN 301 842-4 V1.3.1:2015
ETSI ETSI EN 301 842-4 V1.3.1 (2015-04) 11 CTRL ConTRoL (DLPDU) CTS Clear To Send (burst) DLE Data Link Entity DLPDU Data Link Protocol Data Unit DLS Data Link Service DM Disconnected Mode (DLPDU) FRMR FRaMe Reject (DLPDU) GFSK Gaussian filtered Frequency Shift Keying GSC Global Signalling Channel GSIF Ground Station Information Frame hex hexadecimal IA-5 International Alphabet 5 IB Initialize Bit ICAO International Civil Aviation Organization ID IDentity INFO INFOrmation (DLPDU) ISO International Organization for Standardization IS-SME Intermediate System - System Management Entity LCR Link Connection Refused lg length LME Link Management Entity M More bit MAC Media Access Control MOPS Minimum Operational Performance Specification NACK Negative ACKnowledgment NETs Network Entity Titles NM Nautical Mile NSCOP Network Setup Connection Orientated Protocol p priority PCO Point of Control and Observation PI Parameter Identifier R&TTE Radio equipment and Telecommunications Terminal Equipment RF Radio Frequency RTS Request To Send (DLPDU) SARPs Standards And Recommended Practices SNDCF SubNetwork Dependant Convergence Function SZOM Start Zero Overhead Mode (DLPDU) T Toggle bit UCTRL Unacknowledged ConTRoL data broadcast (DLPDU) UDATA Unacknowledged DATA broadcast (DLPDU) UINFO Unacknowledged user INFOrmation data broadcast (DLPDU) VDL VHF Digital Link VHF Very High Frequency VME VDL Management Entity VSS VDL Mode 4 Specific Services ZOCOP Zero Overhead Connection-Orientated Protocol 4 General description of VDL Mode 4 ground station point-to-point services 4.1 General A description of VDL Mode 4 is provided in ETSI EN 301 842-2 [5]. This clause provides a description of the datalink layer and associated services of the VSS and LME required to support point-to-point communications. The specifications in the present document provide air-to-ground and air-to-air point-to-point services based on the ICAO Technical Manual. The present document includes: • Point-to-point data and control data transfer functions from the DLS. SIST EN 301 842-4 V1.3.1:2015
ETSI ETSI EN 301 842-4 V1.3.1 (2015-04) 12 • Point-to-point link control within the LME. Note that the present document covers the establishment, termination and handover of links between ground stations. Decisions to establish, terminate or handover links between ground stations are local issues and beyond the scope of these specifications. In most respects, the VDL Mode 4 ground station follows the provisions of the ICAO standards material for VDL Mode 4. Within the ICAO standard, there are some requirements which apply explicitly only to airborne stations. Requirements on airborne stations are covered in ETSI EN 302 842 [i.1] Parts 1 to 4. The scope of the present document is for a ground station supporting point-to-point applications. Hence the ability to support broadcast communication is not included in the present document. Note that, although certain protocols will not be used by the ground station, the ability to recognize the use by mobiles of these protocols and to respond in a consistent manner is a ground station requirement and is included in the present document. 4.2 Data Link Service (DLS) and Link Management Entity (LME) 4.2.1 General The Data Link Service (DLS) provides a point-to-point protocol supporting both air-to-ground and air-to-air exchanges. For air-to-ground exchanges, connection management is handled by the LME, using a Negotiated Setup Connection-Orientated Protocol (NSCOP). For air-to-air exchanges, the DLS defines a ZOCOP protocol with link establishment and disestablishment controlled by timers, allowing rapid link negotiation between aircraft. The specifications in the present document assume that VDL Mode 4 will be used with a network based on ATN protocols [3]. It should be noted that, in future, it could support other network protocols. The DLS is a simple information exchange protocol which provides: a) Explicit acknowledgement of each DATA packet. b) Mechanisms to provide data transfer in reserved slots, avoiding loss rates and delays associated with random access. This includes the ability to link sequences of DATA packets, providing continuous transfer in reserved slots. c) Packet fragmentation, to allow long user data packets to be transferred across the link in fragments optimally matched to the link conditions. d) Duplicate detection and suppression via a simple toggle-bit mechanism. e) Explicit support for the 15 priority levels defined for the ATN, including the ability for high priority messages to be sent in the middle of a fragmented low priority message. As illustrated in figure 4.1, the DLS: • Provides services to external users in order to support point-to-point, multi-cast and broadcast communications. • Provides services to the LME to support link management. • Supports services between peer DLSs. • Uses the services of the VSS in order to send and receive messages. SIST EN 301 842-4 V1.3.1:2015
ETSI ETSI EN 301 842-4 V1.3.1 (2015-04) 13
Figure 4.1: Functions of the DLS Figure 4.2 illustrates the use of various services provided by the DLS and VSS in supporting the DLS User and the LME.
Figure 4.2: Services provided by the DLS and VSS in support of DLS User and LME Protocols for short unacknowledged broadcast data have already been specified in the core link layer functionality (ETSI EN 301 842-2 [5]). A DLS Burst consists of: • Burst ID (fixed or variable). • One or two DLPDUs. LMEDLS UserDLSPeer DLSVSSDirected Data (INFO, CTRL)Long AcknowledgedShortAcknowledgedLongUnacknowledgedShortUnacknowledgedBurst RetransmissionGeneral Response Protocol (General Failure)Connection Management (IB/SZOM)Message Segmentation (M-bit)Delivery Order (T-bit)Broadcast Data (UDATA)DLSVSSDLS UserLMEResponse ReservationUnicastReservationInformationTransferReservationSIST EN 301 842-4 V1.3.1:2015
ETSI ETSI EN 301 842-4 V1.3.1 (2015-04) 14 The following DATA DLPDUs (Data Link Protocol Data Units) are defined: • CTRL - Used by the LME to establish and maintain links for NSCOP communication. • INFO - Contains a user data field. • UDATA - Either a UCTRL or a UINFO. Enables the broadcast of user data - it is unacknowledged. The following RTS DLPDUs are defined: • CTRL_RTS - Sent to request the sending of link maintenance data. • INFO_RTS - A request to send user data (for long transmission procedures). • UDATA_RTS - A request to send broadcast data. The following ACK, CTS and other DLS link control DLPDUs are defined: • UDATA_CTS - This DLPDU is a clear to send in response to a UDATA_RTS. • INFO_ACK - An acknowledgement of the previous INFO DLPDU. • INFO_CTS - A clear to send (for long transmission procedures). • CTRL_ACK - An acknowledgement of the previous CTRL DLPDU. • FRMR - Used to reset the link. • FRMR_ACK - Sent to acknowledge receipt of FRMR. • DM/DISC (Disconnected Mode) - Used to indicate that a DLS DLPDU has been received when no link has been initialized. • DM/FRMR - Used to indicate that a DLS DLPDU has been received when the link is in the process of being initialized. • SZOM - Sent in combination with an INFO, INFO_RTS or INFO_ACK to establish a link for ZOCOP communication. The following table shows the DLS burst types.
Toggle Bit (T) More Bit (M) Priority (p) Negotiation subfield (neg) Initialize bit IB Length (lg) CTRL
INFO
UDATA
CTRL_RTS
INFO_RTS
UDATA_RTS
UDATA_CTS
INFO_ACK
CTRL_ACK
CTRL_CTS
FRMR_ACK
FRMR
DM/DISC
DM/FRMR
SZOM
Where: • Toggle bit (T): This is used for duplicate detection and rejection. • More bit (M): This is set to zero to indicate the end of a message. It is set to 1 to indicate that it is part of a fragmented message and that there are more fragments to follow. SIST EN 301 842-4 V1.3.1:2015
ETSI ETSI EN 301 842-4 V1.3.1 (2015-04) 15 • Priority (p): This is the priority of the message. • Negotiation subfield (neg): This indicates the link management parameters to be used for air-to-air link control. • Initialize Bit (IB): This bit causes the receiver to initialize the Tt and Tr state variables and to clear the send and receive arrays whilst processing the burst. It is set to zero and ignored on receipt unless otherwise stated. • Length (lg): This is the length of the data message in slots. 4.2.2 DLS timers The following timers are used in the DLS procedures: • TD1: ZOCOP link transmit timer. This timer is reset when a burst is sent to the peer. If it expires, then Tt is set to 0 and the send channel array cleared. • TD2: ZOCOP link receive reset timer. This timer is reset when a burst is received from the peer. If this timer expires then Tt is set to 0, the send channel array is cleared and the link is considered to be terminated. 4.2.3 DLS counters The following counters are used in the DLS procedures: • ND1: Maximum number of octets that may be submitted to the DLS for transfer. • ND2: Maximum length of a DLS transmission that may use the short transmission procedures. • ND3: Maximum length of a fragment in slots with M-bit processing. • ND4: Maximum length of UDATA burst. 4.2.4 Toggle bit (T) The T (Toggle) bit allows detection and rejection of duplicate DLPDUs. The T bit is alternately set to 1 and 0 on each successive DATA transmission, except for retransmissions. The associated RTS, CTS and ACK DLPDUs should have the same value T bit as the DATA packet.
Figure 4.3: Use of the T bit in a short procedure DATA T = 1ACK T = 1DATA T = 0ACK T = 0ABSIST EN 301 842-4 V1.3.1:2015
ETSI ETSI EN 301 842-4 V1.3.1 (2015-04) 16 4.2.5 State variables (Tt and Tr) When a message being transmitted is not the first message between the two stations, the sending station sets the T bit to the inverse value that it had for the previous message. The value it transmitted previously is stored in the state variable Tt. The receiving station compares the value of the T bit it receives with the value it received previously, to check that the received T bit is of the correct value. The value it received previously is stored in the state variable Tr. When the sending station receives an ACK or a CTS, it compares the value of the T bit with the val
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