ETSI TS 137 462 V15.2.0 (2020-01)

ETSI TS 137 462 V15.2.0 (2020-01)






TECHNICAL SPECIFICATION
Universal Mobile Telecommunications System (UMTS);
LTE;
5G;
Iuant interface: Signalling transport
(3GPP TS 37.462 version 15.2.0 Release 15)

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3GPP TS 37.462 version 15.2.0 Release 15 1 ETSI TS 137 462 V15.2.0 (2020-01)



Reference
RTS/TSGR-0337462vf20
Keywords
5G,LTE,UMTS
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3GPP TS 37.462 version 15.2.0 Release 15 2 ETSI TS 137 462 V15.2.0 (2020-01)
Intellectual Property Rights
Essential patents
IPRs essential or potentially essential to normative deliverables 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.
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ETSI claims no ownership of these except for any which are indicated as being the property of ETSI, and conveys no
right to use or reproduce any trademark and/or tradename. Mention of those trademarks in the present document does
not constitute an endorsement by ETSI of products, services or organizations associated with those trademarks.
Legal Notice
This Technical Specification (TS) has been produced by ETSI 3rd Generation Partnership Project (3GPP).
The present document may refer to technical specifications or reports using their 3GPP identities. These shall be
interpreted as being references to the corresponding ETSI deliverables.
The cross reference between 3GPP and ETSI identities can be found under http://webapp.etsi.org/key/queryform.asp.
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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3GPP TS 37.462 version 15.2.0 Release 15 3 ETSI TS 137 462 V15.2.0 (2020-01)
Contents
Intellectual Property Rights . 2
Legal Notice . 2
Modal verbs terminology . 2
Foreword . 4
1 Scope . 5
2 References . 5
3 Definitions and abbreviations . 5
3.1 Definitions . 5
3.2 Abbreviations . 6
4 Iuant data link layer . 6
4.1 Invalid receptions . 6
4.2 Frame lengths . 6
4.3 Default address . 7
4.4 Window size . 7
4.5 Message timing . 7
4.6 State model . 7
4.7 Device types . 7
4.8 XID negotiation . 8
4.8.1 HDLC parameters . 8
4.8.2 Protocol version . 8
4.8.3 Address assignment . 8
4.8.4 Device scan . 9
4.8.5 Reset device . 9
4.9 Link establishment . 10
4.10 Link timeout . 10
Annex A (informative): HDLC description . 11
A.1 Basic structure . 11
A.2 UNC commands . 12
A.2.1 Set Normal Response Mode (SNRM) . 12
A.2.2 Disconnect (DISC) . 12
A.2.3 Unnumbered Acknowledge (UA) . 12
A.2.4 Disconnected Mode (DM) . 12
A.2.5 Receiver Ready (RR) . 12
A.2.6 Receiver Not Ready (RNR) . 12
A.2.7 Information (I) . 12
A.2.8 Frame Reject (FRMR) . 12
A.3 Option 1 . 13
A.4 Option 4 . 13
A.5 Option 15.1 . 13
A.6 Link safety . 13
A.7 Full duplex link . 13
Annex B (informative): HDLC parameter negotiation . 15
Annex C (informative): HDLC parameter negotiation example . 16
Annex D (informative): Address assignment example . 17
D.1 Address assignment command . 17
D.2 Address assignment response . 17
Annex E (informative): Device scan example . 18
Annex F (informative): Change History . 20
History . 21

ETSI

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3GPP TS 37.462 version 15.2.0 Release 15 4 ETSI TS 137 462 V15.2.0 (2020-01)
Foreword
rd
This Technical Specification has been produced by the 3 Generation Partnership Project (3GPP).
The contents of the present document are subject to continuing work within the TSG and may change following formal
TSG approval. Should the TSG modify the contents of the present document, it will be re-released by the TSG with an
identifying change of release date and an increase in version number as follows:
Version x.y.z
where:
x the first digit:
1 presented to TSG for information;
2 presented to TSG for approval;
3 or greater indicates TSG approved document under change control.
y the second digit is incremented for all changes of substance, i.e. technical enhancements, corrections,
updates, etc.
z the third digit is incremented when editorial only changes have been incorporated in the document.

ETSI

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3GPP TS 37.462 version 15.2.0 Release 15 5 ETSI TS 137 462 V15.2.0 (2020-01)
1 Scope
The present document specifies the signalling transport related to RETAP and TMAAP signalling to be used across the
Iuant interface for UTRAN, E-UTRAN and NG-RAN. In this specification UTRAN, E-UTRAN and NG-RAN are
denoted as "RAN", whereas the corresponding network entities Node B, eNB, en-gNB and NG-RAN node are denoted
as "RAN Node". The logical Iuant interface is an interface internal to the RAN Node and defined to reside between the
implementation specific O&M function and the RET antennas and between the implementation specific O&M function
and the TMA control unit function.
2 References
The following documents contain provisions which, through reference in this text, constitute provisions of the present
document.
● References are either specific (identified by date of publication, edition number, version number, etc.) or
non-specific.
● For a specific reference, subsequent revisions do not apply.
● For a non-specific reference, the latest version applies. In the case of a reference to a 3GPP document (including
a GSM document), a non-specific reference implicitly refers to the latest version of that document in the same
Release as the present document.
[1] Void
[2] ISO/IEC 13239 (3rd Edition, 2002-07): "Information Technology – Telecommunications and
information exchange between systems – High-level data link control (HDLC) procedures".
[3] 3GPP TS 37.461: "Iuant Interface: Layer 1".
[4] Antenna Interface Standards Group: "Control Interface for Antenna Line Devices", Standard
No. AISG v2.0
3 Definitions and abbreviations
3.1 Definitions
For the purposes of the present document, the following terms and definitions apply.
ASCII character: A character forming part of the International Reference Version of the 7-bit character set defined in
ISO/IEC 646:1991 represented as one octet
Octet: 8 bits as used in ISO/IEC 13239 [2]
Device type: One octet identifying the type of a device
Unique ID: A concatenation of the vendor code (2 octets) and a 1 to 17 octets long unit specific code (e.g. serial
number) exclusive for each secondary device from the vendor to whom the vendor code is assigned. The vendor code is
placed in the left-most (most significant) position of the unique ID. The vendor to whom the vendor code is assigned is
responsible for ensuring the uniqueness of the unique ID for each device.
Vendor code: A unique ASCII 2-character code assigned to each vendor in AISG v2.0 [4].
Reset: A process by which the device is put in the state it reaches after a completed power-up
SecondaryPayloadTransmitLength: The maximum length of the INFO field of an HDLC I-frame in the direction
secondary device to primary device.
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3GPP TS 37.462 version 15.2.0 Release 15 6 ETSI TS 137 462 V15.2.0 (2020-01)
SecondaryPayloadReceiveLength: The maximum length of the INFO field of an HDLC I-frame in the direction
primary device to secondary device.
3.2 Abbreviations
For the purposes of the present document, the following abbreviations apply:
ADDR Address
ACK Acknowledgment
CRC Cyclic Redundancy Check
DISC Disconnect (frame type)
DM Disconnected Mode (frame type)
FCS Frame Checking Sequence
FI Format Identifier
FRMR Frame Reject (frame type)
GI Group Identifier
GL Group Length
HDLC High-Level Data Link Control
I Information (frame type)
ID Identifier
INFO Information (field name)
NAK Non Acknowledgment
NRM Normal Response Mode
P/F Poll/Final
PI Parameter Identifier
PL Parameter Length
PV Parameter Value
RET Remote Electrical Tilting
RETAP Remote Electrical Tilting Application Part
RNR Receive Not Ready (frame type)
RR Receive Ready (frame type)
SNRM Set Normal Response Mode (frame type)
TMA Tower Mounted Amplifier
TMAAP Tower Mounted Amplifier Application Part
TWA Two Way Alternate
UA Unnumbered Acknowledgement (frame type)
UNC Unbalanced Operation Normal Response Mode Class
XID Exchange ID (frame type)
4 Iuant data link layer
The Data Link Layer uses HDLC Class UNC1,15.1 TWA (see 6.10 in ISO/IEC 13239 [2]) according to ISO/IEC 13239
[2].
4.1 Invalid receptions
Frames shall be discarded if a framing error or data overrun occurs.
4.2 Frame lengths
HDLC frame lengths may vary between 4 and N octets.
All secondary devices shall support an N of 78 octets. A secondary device may, after XID negotiation, support a larger
N.
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4.3 Default address
After reset, a secondary device shall use the no-device address (0x00). While it has the no-device address, it may only
respond to device scan and address assignment messages, but any broadcast messages shall be evaluated without
response.
4.4 Window size
All devices shall support a window size of 1. A device may, after XID negotiation, support any window size up to 7.
4.5 Message timing
A minimum of 3 ms shall elapse between receiving and transmitting messages.
A secondary device shall, after reception of a command with the P/F bit set, start transmitting a response within 10 ms
from the time the final flag octet of that command frame was received.
The transmission of the response shall be finalised within the time t= n*10*4/datarate where n is the number of octets in
the response frame including all HDLC framing overhead. The maximum gap time between two consecutive octets
shall not exceed the time t= 3*10/datarate. This corresponds to a 25% utilisation of the Data Link Layer.
The data rate is specified in TS 37.461 [3].
4.6 State model
The connection state model for the layer 2 of the secondary device is shown in figure 4.1. The events written in italic
are procedures from higher levels e.g. link establishment. The HDLC frames that correspond to the events are written in
bold as command / response messages.

Reset (reset, power on, watchdog etc.)
Link Timeout
Address
NoAddress
Configuration
XID/XID
Link Disconnection AddressAssigned
DISC/UA
SNRM/UA
Link Establishment
Connected

Figure 4.6.1: Connection state model
4.7 Device types
Three device types are defined and identified by the assigned 1-octet unsigned integer code.
ETSI

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Table 4.7.1: Device types and codes
Device Type 1-octet unsigned integer code
Single-Antenna RET Device 0x01
Multi-Antenna RET Device 0x11
Tower mounted amplifier (TMA) 0x02

4.8 XID negotiation
XID negotiation shall use the standard format (see 5.5.3.1-5.5.3.2.3.2 in ISO/IEC 13239 [2]). See Annex B for a brief
description of XID negotiation and Annex C to E for examples of XID negotiations. All GL fields have a size of 1 octet.
Any parameter combination of 4.8.1 (HDLC parameter), 4.8.2 (Protocol Version) and 4.8.3 (Address assignment) in an
XID command shall be supported by all secondary devices.
4.8.1 HDLC parameters
Format Identifier (FI) shall be 0x81 and Group Identifier (GI) shall be 0x80. All secondary devices shall support the
following parameters:
Table 4.8.1.1: HDLC parameters for secondary devices
PI PL Description of PV
5 4 Maximum information field length – transmit (bits)
6 4 Maximum information field length – receive (bits)
7 1 Window size – transmit (frames)
8 1 Window size – receive (frames)

The SecondaryPayloadTransmitLength shall be 74 octets by default. It can be increased via XID negotiation, but shall
always be 74 octets or larger.
The SecondaryPayloadReceiveLength shall be 74 octets by default. It can be increased via XID negotiation, but shall
always be 74 octets or larger.
4.8.2 Protocol version
Format Identifier (FI) shall be 0x81 and Group Identifier (GI) shall be 0xF0. All secondary devices shall support the
following parameter:
Table 4.8.2.1: HDLC parameter for protocol version
PI PL Description of PV
5 1 3GPP Release ID

4.8.3 Address assignment
The primary device broadcasts the XID commands. The secondary device(s) which match shall respond. The primary
shall ensure that only one secondary matches the supplied parameter(s). See below for details.
Format Identifier (FI) shall be 0x81 and Group Identifier (GI) shall be 0xF0. All secondary devices shall support the
following parameters:
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3GPP TS 37.462 version 15.2.0 Release 15 9 ETSI TS 137 462 V15.2.0 (2020-01)
Table 4.8.3.1: HDLC parameters for address assignment and device scan
PI PL Description of PV
1 0 to 19 Unique ID
2 1 HDLC Address
3 0 to 19 Bit Mask (for Unique ID), indicates a device scan
4 1 Device Type (see table 4.7.1)
6 2 Vendor Code as given in AISG v2.0 [4]

The XID message can be used to assign HDLC addresses or to scan for devices.
An address assignment XID command shall contain at least PI=2 (HDLC Address) and shall not contain PI=3 (Bit
Mask). During an address assignment all secondary devices first assume a match and then carry out the following steps:
- If PI=1 (Unique ID) is supplied, the right-most PL octets of the secondary devices Unique ID are compared to
the Unique ID in the XID command. If they are different, the secondary device does not match, and the message
is ignored. If the Unique ID in the XID command is longer than the secondary devices Unique ID, the secondary
device does not match, and the message is ignored.
- If PI=4 (Device Type) is supplied, the device type of the secondary device is compared to the device type in the
XID command. If they are different, the secondary device does not match, and the message is ignored.
- If PI=6 (Vendor Code) is supplied, the vendor code of the secondary device is compared to the vendor code in
the XID command. If they are different, the secondary device does not match, and the message is ignored.
If the secondary device still matches after these steps, the secondary device sets its HDLC address to the address
specified in PI=2 and responds with an XID response which contains PI=1 and PI=4.
NOTE: Unlike the normal XID negotiation, in this XID negotiation, the XID response message returns a different
set of parameters than the XID command message.
4.8.4 Device scan
The device scan messages may be utilised by the primary to identify all secondary stations in the NoAddress state on an
interface .
A device scan XID command shall only contain PI=1 (Unique ID) and PI=3 (Bit Mask), see table 4.8.3.1. PI=1 and
PI=3 shall be of equal length PL octets.
If in the NoAddress state, the secondary device masks the min(PL,2) left-most octets of its own unique ID with the
min(PL,2) left-most octets of the bit mask in the XID command and compares the result with the min(PL,2) left-most
octets the unique ID supplied in the XID command. If they match, the secondary device masks the max(0,PL-2) right-
most octets of its own unique ID with the max(0,PL-2) right-most octets of the bit mask in the XID command and
compares the result with the max(0,PL-2) right-most octets of the unique ID supplied in the XID command. If they also
match, the secondary device transmits an XID response message with its own identification data in the fields PI=1
(complete unique ID), PI=4 (device type) and PI=6 (vendor code).
For the device scan comparison, the unique ID of the secondary device shall be padded with NUL characters (character
code 0x00) between the second and third left-most positions to a length of 19 octets.
The scan command with zero length (PL=0) of the Unique ID (PI=1) and the Bit Mask (PI=3) shall match all secondary
devices in the NoAddress state.
Only matching secondary devices in the NoAddress state shall respond to the device scan messages.
4.8.5 Reset device
Format identifier (FI) shall be 0x81 and group identifier (GI) shall be 0xF0. All secondary devices shall support the
following parameter:
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3GPP TS 37.462 version 15.2.0 Release 15 10 ETSI TS 137 462 V15.2.0 (2020-01)
Table 4.8.5.1: HDLC parameters for reset of secondary devices
PI PL Description of PV
7 0 Reset device

If the XID command reset device is received as a broadcast (0xFF) by the secondary device, the secondary device shall
reset without responding, otherwise the addressed secondary device shall reset after responding.
The reset device parameter shall not be combined with other parameters in an XID command.
NOTE: There is no PV in the XID command Reset device.
4.9 Link establishment
Once the secondary device has been assigned an HDLC address, the primary device initiates the link establishment by
sending the SNRM command frame. The secondary device responds with an UA frame and enters the state Connected.
4.10 Link timeout
Whenever a secondary device receives an HDLC frame addressed to itself, i.e. not an all-device address (0xFF), it shall
restart a 3 minute timer. If this 3 minute timer expires, the secondary device shall be reset.
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Annex A (informative):
HDLC description
HDLC is defined in ISO/IEC 13239 [2]. This description only covers the aspects of HDLC which are used by this TS.
The HDLC definition “UNC1,15.1, TWA” can be broken down to:
- UNC;
- The “U” means Unbalanced operation (master slave operation);
- The “N” means Normal response mode (sequence numbers used in data frames);
- The “C” means Class.
- Options supported;
- “1” means use of XID negotiation;
- “15.1” means use of start/stop transmission with basic transparency;
- Two Way Alternate (TWA) is the HDLC term for half duplex.
A.1 Basic structure
In unbalanced operation, there is one primary station (master) which controls the bus and a number of secondary
stations (slaves) which only are allowed to transmit when the primary station gives them permission to do so.
All messages are transmitted as frames with the layout shown in table A.1.1:
Table A.1.1: Format of an HDLC frame
Flag ADDR Control INFO FCS Flag
1 octet 1 octet 1 octet N octets 2 octets 1 octet
0x7E Secondary Station Control bits Variable length CRC 0x7E
Address

HDLC frames begin and end with a Flag (0x7E) (see A.5 for details).
The transmitting station calculates a Frame Check Sequence (CRC16) on all octets which follow the starting flag but
not including the FCS octets. The checksum is transmitted as FCS in little endian order and is followed by the closing
flag.
The receiving station calculates the checksum on all octets between the flags. When it finds the closing flag, it compares
the checksum to 0xF0B8. If it is a match, the HDLC frame is processed.
The address field contains the HDLC address of the secondary station. If the primary station sends the message, it is
called a command and the address field contains the address of the secondary station as destination. If the secondary
station sends the message, it is called a response and the address field contains the address of the secondary station as
source. Secondary stations cannot communicate directly to each other.
The control field defines one of three frame types:
- I frames contain data as well as a send and receive counter;
- S frames contain a receive counter;
- U frames contain unnumbered commands.
The INFO field is only present in I frames and XID frames. The INFO field in an I frame contains the layer 7 payload.
ETSI

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A.2 UNC commands
According to 6.6.2.1 in ISO/IEC 13239 [2] the following commands in shall be supported in UNC mode:
Table A.2.1: Commands supported in UNC mode
Commands  Responses
(Primary Station) (Secondary Station)
Frame type I Frame type I
Frame type RR Frame type RR
Frame type RNR Frame type RNR
Frame type SN
...