ETSI TR 102 300-6 V1.1.2 (2016-05)

ETSI TR 102 300-6 V1.1.2 (2016-05)






TECHNICAL REPORT
Terrestrial Trunked Radio (TETRA);
Voice plus Data (V+D);
Designers' guide;
Part 6: Air-Ground-Air

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2 ETSI TR 102 300-6 V1.1.2 (2016-05)



Reference
RTR/TCCE-01205
Keywords
radio, TETRA
ETSI
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3 ETSI TR 102 300-6 V1.1.2 (2016-05)
Contents
Intellectual Property Rights . 5
Foreword . 5
Modal verbs terminology . 5
1 Scope . 6
2 References . 6
2.1 Normative references . 6
2.2 Informative references . 7
3 Definitions and abbreviations . 7
3.1 Definitions . 7
3.2 Abbreviations . 8
4 What is different about Air-Ground-Air operation and why is it needed? . 8
4.1 General . 8
4.2 Spectrum. 9
5 Technical Design . 9
5.1 Concept of Overlay Network. 9
5.2 Spectrum Allocation . 10
5.3 Non-Harmonised Frequencies . 10
5.4 Cell Operational Size . 10
5.5 Neighbouring . 11
5.6 Subscriber Class . 11
5.7 Preferred Location Area . 12
5.8 Subscriber Class or Preferred Location Area . 12
5.9 Radio Handovers . 12
5.10 AGA Cell Aspects . 13
5.10.1 Antenna Type . 13
5.10.2 Shared Antennas . 13
5.10.3 Antenna location on masts . 13
5.10.4 Feeder Types and Design Rules vs. Length . 13
5.10.5 Antenna Mounting Arrangement . 14
5.10.6 Base Radio RF Parameters . 14
5.10.7 Reselection Parameters . 14
5.11 AGA network planning . 14
5.11.1 General design considerations for an AGA network . 14
5.11.2 International Frequency Co-ordination . 15
5.11.3 Design of the pan-European AGA radio plan . 15
5.11.4 Characteristics of the pan-European AGA radio plan . 17
6 Configuration . 17
6.1 Capacity Planning. 17
6.2 System Restriction Control. 17
6.3 User Priority . 17
6.4 Security . 17
6.5 Packet Data . 18
6.6 Resilience . 18
6.7 Radio Cell Fallback Strategy . 18
6.8 Exception Conditions . 18
7 Airframe considerations . 18
7.0 General . 18
7.1 Mobile Stations . 19
7.1.0 General . 19
7.1.1 Mobile Stations - Aircraft specific MSs . 19
7.1.2 Multiple Mobile Stations . 19
7.1.3 Mobile Stations - Hand Held equipments . 20
7.1.4 Mobile Stations - Vehicle MSs . 20
ETSI

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4 ETSI TR 102 300-6 V1.1.2 (2016-05)
7.1.5 Emergency Call Operation . 20
7.2 Mobile Station Configuration . 20
7.2.0 General . 20
7.2.1 Subscriber Class operating methodology configuration . 20
7.2.2 Preferred Location Area operating methodology configuration . 21
7.2.3 Common operating methodology configuration . 21
7.2.4 Aircraft Antenna Configuration . 21
7.2.5 Certification . 21
7.3 Mobile Station Upgrades . 22
Annex A: Europe wide AGA frequency plan . 23
History . 45

ETSI

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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 (https://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 Technical Report (TR) has been produced by ETSI Technical Committee TETRA and Critical Communications
Evolution (TCCE).
The present document is part 6 of a multi-part deliverable covering Terrestrial Trunked Radio (TETRA); Voice plus
Data (V+D); Designers' guide, as identified below:
ETSI ETR 300-1: "Overview, technical description and radio aspects";
ETSI TR 102 300-2: "Radio channels, network protocols and service performance";
ETSI TR 102 300-3: "Direct Mode Operation (DMO)";
ETSI ETR 300-4: "Network management";
ETSI TR 102 300-5: "Guidance on numbering and addressing";
ETSI TR 102 300-6: "Air-Ground-Air".
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

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6 ETSI TR 102 300-6 V1.1.2 (2016-05)
1 Scope
The present document is written as a "Read-me-first" manual or "Getting started with TETRA Air-Ground-Air". It is
not intended to be a guide to the TETRA Air-Ground-Air standard nor an authoritative interpretation of the standard. If
any conflict is found between the present document and the corresponding sections in the TETRA standard then the
standard takes precedence.
The reader of the present document is assumed to have a working knowledge TETRA technology. The guidance
provided in the present document is prepared with the experience of implementing an Air-Ground-Air to an existing
national network.
The aims of the present document are:
• to introduce and detail the different aspects of Air-to-Ground communication in a TETRA network;
• to show the reader that Air-Ground-Air is an integral part of a TETRA network when required;
• to provide the reader with sufficient knowledge to engage in qualified discussions with the equipment and
service suppliers;
• to expose the reader to the specific language and technical terminology used in the present document;
• to enable the reader to understand the flexibility in system design, system network topography, system
availability, various modes of operation and security features;
• to provide basic guidance on optimizing a TETRA network when including an Air-Ground-Air element.
The present document provides guidance on the requirements for an Air-Ground-Air service and how best to implement
an AGA service.
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
https://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.
Not applicable.
ETSI

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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] ECC/DEC/(06)05: "ECC Decision of 7 July 2006 on the harmonised frequency bands to be
designated for Air-Ground-Air operation (AGA) of the Digital Land Mobile Systems for the
Emergency Services".
[i.2] ETSI EN 300 392-2: "Terrestrial Trunked Radio (TETRA); Voice plus Data (V+D); Part 2: Air
Interface (AI)".
[i.3] ETSI EN 300 392-7: "Terrestrial Trunked Radio (TETRA); Voice plus Data (V+D);
Part 7: Security".
[i.4] TETRA MoU - TTR 001-16: "TETRA Interoperability Profile - Part 16 (Air to Ground)".
[i.5] Recommendation ITU-R P.528-2: "Propagation curves for aeronautical mobile and
radionavigation services using the VHF, UHF and SHF bands".
3 Definitions and abbreviations
3.1 Definitions
For the purposes of the present document, the following terms and definitions apply:
path delay function: cell reselection initiated by path delay
NOTE: The time taken for signal to perform a round-trip between the MS and Cell is known as the "Path Delay".
When this time exceeds a preset value the SwMI informs the MS that maximum path delay is exceeded
and causes the MS to initiate cell reselection.
Preferred Location Area (PLA): set of cells MS prefers against other cells
NOTE: A number of Location Area Codes may be programmed into the MS. The MS on receiving one or more of
these LAs in the neighbour list of the cell it is affiliated to will "prefer" to use the cell associated with one
of those LAs. Mobility to and away from such cells is defined in ETSI EN 300 392-2, clause 18 [i.2] and
TETRA Interoperability Profile 16 [i.4]. PLAs may also be known as "Home Location Areas".
RF carrier: distinct radio frequency on which radio channel may be active
Subscriber Class (SC): subdivision of the subscriber population
NOTE: There are 16 subscriber classes defined for use on TETRA networks. Those 16 classes are divided into
3 groups, Highly Preferred Subscriber Class, Preferred Subscriber Class and (Basic) Subscriber Class.
Mobility between the 3 groups of subscriber class is defined in ETSI EN 300 392-2 [i.2] and TETRA
Interoperability Profile 16 [i.4].
V+D operation: mode of operation for communication via the TETRA V+D air interface which is controlled by the
TETRA Switching and Management Infrastructure (SwMI)
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3.2 Abbreviations
For the purposes of the present document, the following abbreviations apply:
AGA Air-Ground-Air
AGA_MS Air-Ground-Air Mobile Station
AGL Above Ground Level
ATG Air To Ground (Also A2G)
BS Base Station
DC Direct Current
DMO Direct Mode Operation
ECC Electronic Communications Committee
EIRP Equivalent Isotropic Radiated Power
EMC ElectroMagnetic Compatibility
HF High Frequency
HPSC Highly Preferred Subscriber Class
LA Location Area
MCCH Main Control CHannel
MMI Man Machine Interface
MS Mobile Station
PD Packet Data
PLA Preferred Location Area
PSC Preferred Subscriber Class
PSS Public Safety Spectrum
PTT Press To Talk switch, otherwise known as pressel
RF Radio Frequency
RSSI Radio Signal Strength Indication
RX Receive
SC Subscriber Class
SwMI Switching and Management Infrastructure
SWR Standing Wave Ratio
TMO Trunked Mode Operation
TX Transmit
TX/RX Transmit/Receive
V+D Voice plus Data (trunked infrastructure)
VHF Very High Frequency
4 What is different about Air-Ground-Air operation and
why is it needed?
4.1 General
TETRA radio networks are, in the main, built to provide communications where most subscribers are operating terminal
equipment at sea or at ground level. There are a number of users, however, whose communication needs require
operation at thousands of feet above ground level.
Air-Ground-Air (AGA) operation, also known as Air-To-Ground (ATG or A2G) is a TETRA radio service designed to
provide communication between radio users operating from airborne assets and ground based operatives including radio
users and dispatchers. The airborne assets typically will be comparatively small in number operating comparatively
infrequently. However once they are operational their effectiveness is highly valued.
Most TETRA radio networks are primarily designed as a cellular network providing a land-mobile radio service, so
significant design changes have to be implemented to service the requirements for effective AGA use.
The AGA service is provided by deploying an overlay network of Radio Cells or "Air Cells" that provide the user with
communications typically from 500 feet (150 m) upwards.
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4.2 Spectrum
The spectrum for AGA use is reserved solely for AGA purposes. There are several reasons for this, including:
• Radio channels are a scarce resource. Fortunately they can be re-used at a distance. This is possible due to the
path loss caused by distance, landscape and buildings. In land-mobile networks the re-use distance is typically
50 km due to the high path loss of landscape and buildings. Path Loss at altitude is much less than at ground
level. Transmitting at altitude on a land mobile network would result in interference on several land-mobile
Base Stations that re-use the same radio channel. The EU-wide network plan, see annex A, if followed closely
will minimize co-channel interference to acceptable levels. An internationally agreed frequency allocation is
easier to implement to minimize interference between networks, refer to ECC/DEC/(06)05 [i.1].
• A small number of widely spaced radio cells supplying service for AGA purposes.
• The cells will radiate at lower power than cells used in the ground network.
5 Technical Design
5.1 Concept of Overlay Network
Due to the limited range of RF signals radio networks normally have a cellular structure where channels are re-used at a
regular distance. If the terrestrial network with typical cell sizes of 8 km radius were planned in such a way that it
allowed aircraft communications at normal operational attitudes for public safety or private mobile radio users, more
than 1 000 channels would be required to avoid co-channel interference. As the available spectrum will support many
fewer channels, this is clearly a non-viable technical solution. An efficient means of using the available spectrum is
outlined in the following paragraphs.
Operators should answer this by deploying two networks - one optimized for terrestrial use and a second network
designed for airborne radios.

Figure 1: Terrestrial and Air-Ground-Air network
The terrestrial network is planned to the normal guidelines, whilst the AGA network is frequency planned specifically
to allow for long frequency re-use distances. In order to maintain spectral efficiency, the AGA cells, here after referred
to as "Air Cells" are spaced wide apart and typically have only a single RF carrier at each radio cell.
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AGA terminals will roam seamlessly across the two networks without user intervention. The terminals design for use in
the AGA service will additionally prefer to use the AGA network, utilizing mobility management techniques described
later. Similarly, terrestrial terminals will be restricted to the ground network using the same techniques. As both
networks will offer the same services and facilities, the user (either ground or Air-Ground-Air) is not expected to be
aware of which network they are using.
The operational design is that the aircraft radio(s) will use the terrestrial network from ground level to an altitude where
the AGA signal is received at the value "Radio Usable"; to prevent co-channel interference to ground cells the handover
to an air cell should occur before an altitude of 500 feet (150 m) is achieved.
On descent, the operational design is that the aircraft radio(s) will use the AGA to an altitude where the AGA signal is
received at the value "Radio Relinquishable" and a ground cell signal is received at a stronger level; this design ensures
the aircraft radios are most likely to select the local ground cell. Again, this is to prevent co-channel interference to
ground cells the handover from an air cell should occur at a low altitude, considerably less than 500 feet (150 m).
All radio cells are configured to broadcast information that allows suitably configured terminals to identify the network
type that they belong to them and to handover to the appropriate radio cell. This assumes that certain other conditions
are met; for instance, minimum received signal strength.
5.2 Spectrum Allocation
With ECC/DEC/(06)05 [i.1] a quantity of spectrum has been reserved for public safety AGA operational purposes in
the PSS allocation. This reserved sub-band is the upper end of the PSS allocation. It consists of 8 channels reserved
exclusively for AGA operations and an additional 2 optional ones to be utilized on the operators needs.
Figure 2 illustrates the European-wide harmonised spectrum layout for public safety networks.
International
International
Terrestrial &
AGA Channels
Terrestrial &
AGA Channels
DMO Channels
DMO Channels
Base receives Base transmits
Mobile transmits Mobile receives
Frequency (MHz)
380 385 390 395 400

Figure 2: European Harmonised Spectrum Allocation
in the 380 MHz to 400 MHz frequency range for Public Safety
5.3 Non-Harmonised Frequencies
Where the service requirements of individual operator or country calls for extra AGA RF carriers are required these
additional carriers for AGA use, these carriers will have to be allocated from the terrestrial sub-band then consideration
to exported interference to neighbour authorities and operators be undertaken as part of the planning process. It is
worthwhile reviewing those frequencies when setting up bilateral agreements between countries.
5.4 Cell Operational Size
Clause 4.2 describes why the operational footprint of an air cell is much larger than a ground cell as in "free space" the
path loss is much less. Due to line-of-sight propagation the usable signal from an air cell can extend hundreds of
kilometres, depending on altitude; such distances will take the signal a finite time to cover those distances. It is
important that the round-trip time of the signal taken to transit between the BS and MS should not exceed the guard
time between timeslots.
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5.5 Neighbouring
To allow smooth cell reselection in the AGA network and smooth switching between the terrestrial and the AGA
network neighbour cell relations have to be defined in the TETRA network.
The neighbouring for AGA purposes needs to be considered in 3 ways.
Unlike the neighbouring for terrestrial cells where the cell to cell neighbouring is normally limited to the immediate,
contiguous, neighbouring cells and is reciprocal this is not true of neighbouring to and from air cells. This is due to
there being many more ground cells compared to air cells in any network.
Cell neighbouring type 1 - Ground cell to air cell (as known as "Upwards" neighbouring):
• All ground cells that are under the operational area of an air cell should list that air cell in its neighbour list
broadcast. If a ground cell is located where more than one air cell may provide service then all these air cells
may be included in the neighbour list.
Cell neighbouring type 2 - Air cell to air cell (as known as "Sidewards" neighbouring):
• Neighbouring air cell to air cell should list the immediate or contiguous neighbours only, typically no more
than eight dependent upon frequency reuse pattern, ground terrain and the number of air cells.
• In mountainous regions air cells may be located below the level of the surrounding hills and so may not have
truly circular coverage.
Cell neighbouring type 3 - Air cell to ground cell (as known as "Downwards" neighbouring):
• Neighbouring from air cell to ground cell should use the following recommended priority order:
1) The ground cell that serves the operating or home location (air field, helipad) of aircraft that operate
within the air cells area.
2) Any other regularly used airfields or helipads within the air cells area.
3) A selection of ground cells using different frequencies to the above sites dispersed at intervals within the
air cells area. This will allow a better transition to the ground network throughout the air cells operating
area. Typically the operating authority will chose no more than 20 ground cells
...