8 SLmAP Procedures

36.4593GPPEvolved Universal Terrestrial Radio Access Network (E-UTRAN)Release 17SLm interface Application Protocol (SLmAP)TS

Tools: ARFCN - Frequency Conversion for 5G NR/LTE/UMTS/GSM

8.1 List of SLmAP Elementary procedures

In the following tables, all EPs are divided into Class 1 and Class 2 EPs (see subclause 3.1 for explanation of the different classes):

Table 8.1.1: Class 1 procedures

Elementary Procedure	Initiating Message	Successful Outcome	Unsuccessful Outcome
Elementary Procedure	Initiating Message	Response message	Response message
Measurement	MEASUREMENT REQUEST	MEASUREMENT RESPONSE	MEASUREMENT FAILURE
SLm Setup	SLm SETUP REQUEST	SLm SETUP RESPONSE	SLm SETUP FAILURE
Reset	RESET REQUEST	RESET ACKNOWLEDGE

Table 8.1.2: Class 2 procedures

Elementary Procedure	Message
Measurement Update	MEASUREMENT UPDATE
Measurement Abort	MEASUREMENT ABORT
Error Indication	ERROR INDICATION

The following applies concerning interference between Elementary Procedures:

– The Reset procedure takes precedence over all other EPs.

8.2 Measurement Procedures

8.2.1 Measurement

8.2.1.1 General

The purpose of the Measurement procedure is to allow the E-SMLC to request the LMU to perform and report UL RTOA measurements for the purpose of UTDOA positioning.

8.2.1.2 Successful Operation

Figure 8.2.1.2.1: Measurement procedure. Successful operation.

The E-SMLC initiates the procedure by sending a MEASUREMENT REQUEST message to the LMU. The E-SMLC shall include the deltaSS IE in the MEASUREMENT REQUEST message if SRS sequence hopping is enabled for that particular measurement. If the deltaSS IE is included in the MEASUREMENT REQUEST message, the LMU shall consider that SRS sequence hopping is enabled for the measurement being requested. If the requested measurement has been successful, the LMU shall reply with a MEASUREMENT RESPONSE message.

8.2.1.3 Unsuccessful Operation

Figure 8.2.1.3.1: Measurement procedure. Unsuccessful operation.

If the LMU cannot successfully measure the UL RTOA for the target UE, it shall respond with a MEASUREMENT FAILURE message indicating the cause of the failure.

8.2.1.4 Abnormal Conditions

Not applicable.

8.2.2 Measurement Update

8.2.2.1 General

The purpose of the Measurement Update Procedure is to notify the LMU of a change in the previously signalled measurement configuration for one or more cells for the UE being positioned.

8.2.2.2 Successful Operation

Figure 8.2.2.2.1: Measurement Update: Successful Operation.

The E-SMLC initiates the procedure by sending a MEASUREMENT UPDATE message. The E-SMLC shall include the deltaSS IE in the MEASUREMENT UPDATE message if SRS sequence hopping is enabled for that particular measurement. If the deltaSS IE is included in the MEASUREMENT UPDATE message, the LMU shall consider that SRS sequence hopping is enabled for the measurement.

Upon receiving the UL RTOA Measurement Configuration IE, the LMU shall overwrite the previously received measurement configuration information.

8.2.2.3 Unsuccessful Operation

Not applicable.

8.2.2.4 Abnormal Conditions

If the LMU cannot identify the previously requested measurement to be modified, it shall ignore the MEASUREMENT UPDATE message without taking further action.

8.2.3 Measurement Abort

8.2.3.1 General

The purpose of the Measurement Abort Procedure is to enable the E-SMLC to abort an on-going measurement identified by the E-SMLC Measurement ID.

8.2.3.2 Successful Operation

Figure 8.2.3.2.1: Measurement Abort Procedure: Successful Operation.

The E-SMLC initiates the procedure by sending a MEASUREMENT ABORT message.

Upon receiving this message, the LMU shall terminate the on-going measurement identified by the E-SMLC Measurement ID and may release any resources previously allocated for the same measurement.

8.2.3.3 Unsuccessful Operation

Not applicable.

8.2.3.4 Abnormal Conditions

If the LMU cannot identify the previously requested measurement to be aborted, it shall ignore the MEASUREMENT ABORT message without taking further action.

8.3 Management procedures

The following paragraphs describe the SLmAP interface management procedures.

8.3.1 SLm Setup

8.3.1.1 General

The purpose of the Setup procedure is to exchange application level data needed for the E-SMLC and the LMU to correctly interoperate on the SLm interface. This procedure shall be the first SLmAP procedure triggered after the TNL association has become operational.

8.3.1.2 Successful Operation

Figure 8.3.1.2.1: SLm Setup procedure: Successful Operation.

The LMU initiates the procedure by sending the SLm SETUP REQUEST message to the E-SMLC including the appropriate data. The E-SMLC responds with an SLm SETUP RESPONSE message.

The exchanged data shall be stored in respective node and used for the duration of the TNL association. When this procedure is finished, the SLm interface is operational and other SLmAP messages can be exchanged.

8.3.1.3 Unsuccessful Operation

Figure 8.3.1.3.1: SLm Setup procedure: Unsuccessful Operation.

If the E-SMLC cannot accept the setup, it shall respond with an SLm SETUP FAILURE with an appropriate cause value.

8.3.1.4 Abnormal Conditions

Not applicable.

8.3.2 Reset

8.3.2.1 General

The purpose of the Reset procedure is to initialise or re-initialise the LMU SLmAP contexts in the event of a failure in either the LMU or E-SMLC. This procedure does not affect the application level configuration data exchanged during, e.g., the SLm Setup procedure.

8.3.2.2 Successful Operation

8.3.2.2.1 Reset Procedure Initiated from the E-SMLC

Figure 8.3.2.2.1.1: Reset procedure initiated from the E-SMLC.

In the event of a failure at the E-SMLC, which has resulted in the loss of some or all transaction reference information, a RESET REQUEST message should be sent to the LMU.

At reception of the RESET REQUEST message the LMU shall abort any other ongoing procedure (except another Reset procedure) on the same SLm interface, delete any measurement information related to the E-SMLC, release associated resources, and respond with the RESET ACKNOWLEDGE message.

8.3.2.2.2 Reset Procedure Initiated from the LMU

Figure 8.3.2.2.2.1: Reset procedure initiated from the LMU.

In the event of a failure at the LMU, which has resulted in the loss of some or all transaction reference information, a RESET REQUEST message shall be sent to the E-SMLC.

At reception of the RESET REQUEST message the E-SMLC shall abort any other ongoing procedure (except another Reset procedure) on the same SLm interface, delete any measurement information related to the LMU, release associated resources, and respond with the RESET ACKNOWLEDGE message.

8.3.2.3 Unsuccessful Operation

Void.

8.3.2.4 Abnormal Conditions

If a Reset procedure is ongoing in the LMU concerning one requesting E-SMLC and the LMU receives a RESET message from the same E-SMLC, the LMU shall respond with the RESET ACKNOWLEDGE message as described in 8.3.2.2.1.

If a Reset procedure is ongoing in the E-SMLC concerning one requesting LMU and the E-SMLC receives a RESET message from the same LMU, the E-SMLC shall respond with the RESET ACKNOWLEDGE message as described in 8.3.2.2.2.

If the requesting entity does not receive RESET ACKNOWLEDGE message, the requesting entity may reinitiate the Reset procedure towards the same receiving entity provided that the content of the new RESET REQUEST message is identical to the content of the previously unacknowledged RESET REQUEST message.

8.3.3 Error Indication

8.3.3.1 General

The Error Indication procedure is initiated by a node in order to report detected errors in one incoming message, provided they cannot be reported by an appropriate failure message.

8.3.3.2 Successful Operation

Figure 8.3.3.2.1: Error Indication procedure

When the conditions defined in clause 10 are fulfilled, the Error Indication procedure is initiated by an ERROR INDICATION message sent from the receiving node.

The ERROR INDICATION message shall contain at least either the Cause IE or the Criticality Diagnostics IE.