Content for TS 37.466 Word version: 18.0.0
1 Scope p. 6
The present document is an introduction to the 3GPP TS 37.46x series of Technical Specifications that define the Iuant Interface. The Iuant interface is applicable 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 together with the TMAs control unit function of the RAN Node.
The present document is applicable for UTRAN, E-UTRAN and NG-RAN and specifies the Remote Electrical Tilting Application Part (RETAP) and the Tower Mounted Amplifier Application Part (TMAAP). 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". RETAP supports the functions of the Iuant interface between the implementation specific O&M transport function and the RET Antenna Control unit function, TMAAP supports the functions of the Iuant interface between the implementation specific O&M transport function and the TMA control function.
2 References p. 6
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.
3 Definitions and abbreviations p. 6
3.1 Definitions p. 6
For the purposes of the present document, the terms and definitions given in TR 21.905 and the following apply. A term defined in the present document takes precedence over the definition of the same term, if any, in TR 21.905.
Active alarm:
An alarm which has an alarm state that has been raised, but not cleared.
Alarm:
Persistent indication of a fault.
Alarm code:
A code that identifies a specific alarm. The alarm code set is a subset of the return code set. The alarm codes are listed in annex A of this TS.
Alarm state:
A condition or state in the existence of an alarm. Alarm states are raised and cleared.
ASCII character:
A character forming part of the International Reference Version of the 7-bit character set defined in ISO/IEC 646:1991.
Calibrate:
Exercise the antenna drive unit over its entire range of travel to ensure fault-free operation and synchronise the measured and actual beam tilt of the antenna.
Configuration data:
A stored table or function defining the relationship between the physical position of the drive and electrical beam tilt.
Data type:
A definition determining the value range and interpretation of a series of octets. The following specified data types are used in this TS:
| Name | Definition |
|---|---|
| AlarmCode | 1 octet unsigned enumerated code All AlarmCode values are listed in Annex A of this TS |
| FieldNumber | 1 octet unsigned enumerated code All field number values are listed in Annex B of this TS |
| ProcedureCode | 1 octet unsigned enumerated code |
| ReturnCode | 1 octet unsigned enumerated code All ReturnCode values are listed in Annex A of this TS |
| TextString | Octets with integer values in the range of 32 to 126 to be interpreted as ASCII characters |
Elementary procedure:
The RETAP and TMAAP protocol consists of elementary procedures (EPs). An elementary procedure is a unit of interaction between the primary device (RAN Node) and the secondary devices (RET or TMAs devices)
An EP consists of an initiating message and possibly a response message.
Two kinds of EPs are used:
Error:
- Class 1: Elementary procedures with response (success or failure).
- Class 2: Elementary procedures without response.
Successful
Class 2 EPs are considered always successful.
- A signalling message explicitly indicates that the elementary procedure has been successfully completed with the receipt of the response.
- A signalling message explicitly indicates that the EP failed.
Deviation of a system from normal operation.
Fault:
Lasting error condition.
Little endian:
The order of transmission in which the least-significant octets of a multi-octet representation of a number are transmitted first. Little endian only applies to binary integer representations.
MaxDataReceiveLength:
SecondaryPayloadReceiveLength minus 3 octets (see subclause 4.8.1 in TS 37.462).
MaxDataTransmitLength:
SecondaryPayloadTransmitLength minus 3 octets (see subclause 4.8.1 in TS 37.462).
Procedure code:
A code identifying an elementary procedure.
Reset:
A process by which the device is put in the state it reaches after a completed power-up.
Return code:
A code which defines information about the outcome of an elementary procedure execution.
Tilt (also downtilt, tilt angle, beamtilt):
The elevation angle between the direction orthogonal to the antenna element axis and the maximum of its main beam in the elevation plane. A positive electrical tilt angle means that the antenna beam is directed below the direction orthogonal to the antenna axis. An antenna has separate values for electrical and mechanical tilt. The mechanical tilt is fixed by the geometry of the installation. In this TS the tilt referred to is always the electrical tilt unless otherwise stated.
Tilt value:
A signed integer used in elementary procedures to define the electrical tilt setting of the antenna. The tilt value is 10 times the antenna electrical tilt angle in degrees.
TMA:
A TMA comprises a low noise amplifier together with its control and monitoring electronics and optional antenna modem.
TMA subunit:
A TMA may comprise more than one TMA subunit. All TMA subunits within one TMA have the same HDLC address and are addressable by an index via the application layer procedures.
3.2 Abbreviations p. 8
For the purposes of the present document, the abbreviations given in TR 21.905 and the following apply. An abbreviation defined in the present document takes precedence over the definition of the same abbreviation, if any, in TR 21.905.
EP
Elementary Procedure
HDLC
High-Level Data Link Control
RET
Remote Electrical Tilting
TMA
Tower Mounted Amplifier
RETAP
Remote Electrical Tilting Application Part
TMAAP
Tower Mounted Amplifier Application Part
TCP
Time-Consuming Procedure
4 General p. 8
4.1 Procedure specification principles p. 8
The principle for specifying the procedure logic is to specify the functional behaviour of the RET antenna control unit and TMA Subunits exactly and completely. The RAN Node functional behaviour is left unspecified.
The following specification principles have been applied for the procedure text in clause 6:
-
The procedure text discriminates between:
- Functionality which "shall" be executed The procedure text indicates that the receiving node "shall" perform a certain function Y under a certain condition. If the receiving node supports procedure X but cannot perform functionality Y requested in the REQUEST message of a Class 1 EP, the receiving node shall respond with the message used to report unsuccessful outcome for this procedure, containing an appropriate cause value.
- Functionality which "shall, if supported" be executed The procedure text indicates that the receiving node "shall, if supported," perform a certain function Y under a certain condition. If the receiving node supports procedure X, but does not support functionality Y, the receiving node shall proceed with the execution of the EP, possibly informing the requesting node about the not supported functionality.
4.2 Forwards and backwards compatibility p. 8
The forwards and backwards compatibility of all versions of the protocol shall be assured by a mechanism in which all current and further messages will not be changed in the future. These parts can always be decoded regardless of the standard version.
New functionalities are added into the specification by introducing new procedures and thus the existing messages are not changed in the future.
4.3 Multi-antenna units p. 9
The RETAP elementary procedures are split into a single-antenna oriented part, a multi-antenna oriented part and a common part for both device types in order to support RET units controlling single- or multi-antenna devices. The RET unit responds, upon request, the number of antennas it controls. All multi-antenna oriented elementary procedures include a parameter stating which antenna the elementary procedure addresses. Antennas are numbered 1 and upwards.
4.4 Integer representation p. 9
Multi-octet integer values are transmitted in little endian order. Signed integers are represented as 2-complement values.
4.5 TMA Subunits p. 9
TMA subunits shall be numbered starting with 1 and proceeding upwards. The error message format for TMA procedures follows that of multiple RET devices.
