ETSI TS 100 392-19-2 V1.1.1 (2019-03)

ETSI TS 100 392-19-2 V1.1.1 (2019-03)
TECHNICAL SPECIFICATION
Terrestrial Trunked Radio (TETRA);
Voice plus Data (V+D);
Part 19: Interworking between TETRA and Broadband systems;
Sub-part 2: Format for the transport of TETRA speech over
mission critical broadband systems
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2 ETSI TS 100 392-19-2 V1.1.1 (2019-03)
Reference
DTS/TCCE-04194
Keywords
broadband, interworking, mission critical
applications, mission critical communications,
radio, security, speech, TETRA, V+D
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Intellectual Property Rights ................................................................................................................................ 5

Foreword ............................................................................................................................................................. 5

Modal verbs terminology .................................................................................................................................... 6

Introduction ........................................................................................................................................................ 6

1 Scope ........................................................................................................................................................ 7

2 References ................................................................................................................................................ 7

2.1 Normative references ......................................................................................................................................... 7

2.2 Informative references ........................................................................................................................................ 7

3 Definition of terms, symbols and abbreviations ....................................................................................... 8

3.1 Terms .................................................................................................................................................................. 8

3.2 Symbols .............................................................................................................................................................. 9

3.3 Abbreviations ..................................................................................................................................................... 9

4 Overview .................................................................................................................................................. 9

5 Broadband Traffic PDU format and procedures .................................................................................... 10

5.1 General on broadband traffic PDU contents ..................................................................................................... 10

5.2 TETRA payload ............................................................................................................................................... 10

5.2.1 TETRA payload encoding .......................................................................................................................... 10

5.2.2 Broadband traffic PDU ............................................................................................................................... 11

5.2.3 Basic Payload .............................................................................................................................................. 12

5.3 Broadband traffic PDU information elements .................................................................................................. 13

5.3.1 Additional information ............................................................................................................................... 13

5.3.2 Basic payload .............................................................................................................................................. 13

5.3.3 E2EE ........................................................................................................................................................... 13

5.3.4 Information element control ....................................................................................................................... 14

5.3.5 Payload type................................................................................................................................................ 14

5.3.6 Phase ........................................................................................................................................................... 14

5.3.7 Phase-0 basic block ..................................................................................................................................... 15

5.3.8 Phase-1 basic block ..................................................................................................................................... 15

5.3.9 Phase-2 basic block ..................................................................................................................................... 15

5.3.10 Signalling packet ........................................................................................................................................ 16

5.3.11 Signalling packet type ................................................................................................................................. 16

5.3.12 Signalling packet status .............................................................................................................................. 16

5.3.13 Speech frame pair number .......................................................................................................................... 16

5.3.14 Speech frame status .................................................................................................................................... 17

5.3.15 Supplementary signalling packet type ........................................................................................................ 17

5.3.16 Traffic type ................................................................................................................................................. 17

Annex A (normative): User information transport in RTP session ................................................. 18

A.1 General ................................................................................................................................................... 18

A.2 RTP usage .............................................................................................................................................. 18

A.3 Session Description Protocol .................................................................................................................. 19

A.3.1 General ............................................................................................................................................................. 19

A.3.2 Protocol Version ("v=") .................................................................................................................................... 19

A.3.3 Origin ("o=") .................................................................................................................................................... 19

A.3.4 Session Name ("s=") ........................................................................................................................................ 19

A.3.5 Connection Data ("c=") .................................................................................................................................... 19

A.3.6 Timing ("t=") .................................................................................................................................................... 19

A.3.7 Media Type ("m=") and associated Attributes ("a=") ...................................................................................... 19

A.3.8 Example of SDP Content ................................................................................................................................. 20

A.4 IANA considerations .............................................................................................................................. 21

A.4.1 General ............................................................................................................................................................. 21

A.4.2 Details .............................................................................................................................................................. 21

Annex B (informative): Change requests ............................................................................................. 22

History .............................................................................................................................................................. 23

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This Technical Specification (TS) has been produced by ETSI Technical Committee TETRA and Critical

The present document is part 19, sub-part 2 of a multi-part deliverable covering the Terrestrial Trunked Radio

Part 14: "Protocol Implementation Conformance Statement (PICS) proforma specification";

Sub-part 1: "Critical Communications Architecture for Interworking between TETRA and Broadband

Sub-part 2: "Format for the transport of TETRA speech over mission critical broadband systems".

NOTE 1: Part 3, sub-parts 6 and 7 (Speech format implementation), part 4, sub-part 3 (Data networks gateway),

part 10, sub-part 15 (Transfer of control), part 13 (SDL) and part 14 (PICS) of this multi-part deliverable

NOTE 2: Some parts are also published as Technical Specifications such as ETSI TS 100 392-2 and those may be

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

"must" and "must not" are NOT allowed in ETSI deliverables except when used in direct citation.

The present document defines a TETRA speech transportation format that may be applied over IP networks using RTP

The present document defines a media format for the transport of TETRA air interface circuit mode speech over IP

The present document does not apply to the transportation of TETRA speech over the TETRA ISI. The transportation of

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 documents which are not found to be publicly available in the expected location might be found at

NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee

The following referenced documents are necessary for the application of the present document.

[1] ETSI TS 100 392-3-8: "Terrestrial Trunked Radio (TETRA); Voice plus Data (V+D);

Part 3: Interworking at the Inter-System Interface (ISI); Sub-part 8: Generic Speech Format

[2] ETSI EN 300 392-2: "Terrestrial Trunked Radio (TETRA); Voice plus Data (V+D); Part 2: Air

[3] ETSI EN 300 395-2: "Terrestrial Trunked Radio (TETRA); Speech codec for full-rate traffic

[4] ETSI EN 302 109: "Terrestrial Trunked Radio (TETRA); Security; Synchronization mechanism

[7] IETF RFC 3264: "An Offer/Answer Model with Session Description Protocol (SDP)".

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

NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee

The following referenced documents are not necessary for the application of the present document but they assist the

[i.1] ETSI TS 122 280: "LTE; Mission Critical Services Common Requirements (3GPP TS 22.280)".

[i.2] ETSI TS 123 379: "LTE; Functional architecture and information flows to support Mission

[i.3] IETF RFC 3095: "RObust Header Compression (ROHC): Framework and four profiles: RTP,

encryption synchronization information: sequence of symbols that is transmitted to the receiving terminal to

synchronize an encryption key stream generator in the receiving terminal with an encryption key stream generator in the

end-to-end encryption: encryption that is applied by an originating terminal or client and is decrypted only by chosen

first half slot signalling packet: signalling packet that is associated with a first half slot speech frame

first half slot speech frame: TETRA ACELP speech frame that can be sent in the first half of a TETRA TDMA time

NOTE: The TETRA ACELP codec generates first half slot speech frames and second half slot speech frames, and

interworking function: function that enables interworking between land mobile radio systems and 3GPP defined

mission critical: quality or characteristic of a communication activity, application, service or device that requires low

setup and transfer latency, high availability and reliability, ability to handle large numbers of users and devices, strong

mission critical system: 3GPP system providing mission critical communication services [i.1]

payload block: information element that can contain a speech frame and/or a partial or full signalling packet

second half slot signalling packet: signalling packet that is associated with a second half slot speech frame

second half slot speech frame: TETRA ACELP speech frame that can be sent in the second half of a TETRA TDMA

NOTE: The TETRA ACELP codec generates first half slot speech frames and second half slot speech frames, and

signalling packet: block of data comprising U-plane signalling or C-plane signalling

speech frame pair: pair of speech frames comprising a first half slot speech frame and a second half slot

speech frame pair number: cyclical sequence number of a speech frame pair and any associated signalling packets

NOTE: The speech frame pair number is incremented at 60 ms intervals even if there are no speech frames or

TDMA frame: repeating time unit comprising a set of timeslots and representing a time subdivision of a frequency

U-plane signalling: TETRA encryption synchronization information and/or user-to-user signalling messages [2]

Independently of SwMI or broadband network implementation, TETRA speech, U-plane signalling and C-plane

The media format defined in the present document allows RTP packets [5] containing TETRA ACELP speech

frames [3] and signalling to be transported through an IP network at 20 ms intervals.

A typical application is end-to-end encrypted voice calls between TETRA users and mission critical users [i.2]:

end-to-end encrypted TETRA speech is carried between the TETRA interworking function (IWF) and mission critical

The transmission defined in the present document is "packet mode" and packets may be subject to jitter. The maximum

jitter is a system specific characteristic. The value of the allowable maximum jitter value is outside the scope of the

TETRA is a radio system where normally at least one end of the communication uses the TETRA air interface. Where

there is a requirement for TETRA equipment to interwork with equipment on a broadband network, TETRA speech and

traffic mode signalling can be transported over the broadband network in "broadband traffic" PDUs. The structure of the

TETRA air interface sets some requirements on the broadband traffic PDU contents and format. The main structure of

TETRA speech encoding and traffic mode signalling is retained. TETRA-compatible MSs, the TETRA SwMI and the

The TETRA speech and traffic mode signalling can originate from a TETRA MS, an MCPTT client [i.2] containing a

TETRA voice media comprises a sequence of speech frame pairs, each pair comprising a first half slot speech frame

and a second half slot speech frame, although individual speech frames may be dropped or "stolen" (i.e. replaced by an

associated signalling packet). The receiver needs to be able to distinguish between first half slot and second half slot

speech frames, and the broadband traffic PDU provides this distinction. A stolen or otherwise unavailable speech frame

is indicated in the broadband traffic PDU to facilitate re-use of the relevant TDMA timeslot for other signalling

purposes within a terminating TETRA system. A second half slot speech frame cannot be stolen unless the first half slot

TETRA traffic mode signalling needs to be associated with a specific speech frame, and the broadband traffic PDU

provides this association. The traffic mode signalling can carry TETRA U-plane signalling [2]. U-plane signalling can

be used to carry end-to-end encryption synchronization information as specified in ETSI EN 302 109 [4].

The traffic mode signalling is carried in a "signalling packet". A signalling packet can contain a TETRA

MAC-U-SIGNAL PDU. The use of this PDU shall be as specified in ETSI EN 300 392-2 [2].

The broadband traffic PDU is transported as RTP payload [5], there being one broadband traffic PDU per RTP packet.

RTP usage is defined in Annex A. Padding bits ensure that the broadband traffic PDUs end on octet boundaries. This

causes the containing RTP packets to end on octet boundaries, as required when sent via UDP.

The protocol has been designed to support the transport of TETRA voice media in the form of speech codec frames

(single/dual) and TETRA U-plane and C-plane services. The present document describes in detail the broadband traffic

PDU formats for TETRA speech codec frames and TETRA U-plane and C-plane services. The generic payload

The payload header (contents control information element) indicates the presence and contents of the payload block

The TETRA speech and signalling are transmitted over the broadband network in RTP packets. The RTP packets are

transmitted at 20 ms intervals in a three-phase cycle (phase-0, phase-1 and phase-2) that allows the 20 ms broadband

delivery rate to be reconciled with the TETRA 60 ms speech frame pair generation rate.

The payload format allows some or all signalling packets to be transmitted without stealing speech frames, facilitating

fast end-to-end encryption synchronization without speech quality loss for TETRA speech that originates and

terminates within the broadband network. The speech frames include a "stealing recommendation" indication that is

used by the TETRA IWF to determine which speech frames to steal when delivering the speech and signalling to a

TETRA SwMI. An originator in the broadband network should set the "stealing recommendation" indication at intervals

suitable for a receiver using a TETRA SwMI as illustrated in ETSI EN 302 109, clause 4.4.3 [4].

When stealing is used, either the first half slot speech frame is stolen or both the first half slot and the second half slot

speech frames are stolen. A second half slot shall not be stolen unless the preceding first half slot has been stolen.

RTP packets contain a timestamp [5]. Because the sample period for speech in the TETRA codec is 0,125 ms and there

are 30 ms of coded speech in each speech frame, the timestamp is incremented by 240 units between RTP packets that

• the timestamp is incremented by 240 units between RTP packets that can contain consecutive speech frames

• an RTP packet that cannot contain a speech frame carries a timestamp equal to that in the immediately

The broadband traffic PDU carries TETRA voice media in the form of speech frames. The PDU may also carry

signalling packets associated with the speech frames. The PDU is comprised of the following information elements, see

• Speech frame pair number: this information element indicates the sequence of speech frame pairs and the

• Information element control: this information element indicates the presence or absence of the "additional

• Additional information: this information element allows for future expansion of the broadband traffic PDU.

• Traffic type: this information element identifies the type of circuit mode speech.

• Basic payload, reserved, reserved, reserved: one of these information elements is selected by the "payload