Content for  TS 23.271  Word version:  17.0.0

If the UE is not using Control Plane CIoT EPS Optimisation and if the UE is in ECM-IDLE state, the UE performs a UE triggered service request as defined in TS 23.401 in order to establish a signalling connection with the MME and assign a specific eNodeB. If the UE is using Control Plane CIoT EPS Optimisation, procedures for Mobile Originated Data Transport in Control Plane CIoT EPS optimisation as defined in TS 23.401 are performed by the UE to establish a signalling connection with the MME.

The UE sends a NAS PDU containing an MO-LR Request inside an RRC UL Information Transfer message to the eNodeB. The MO-LR Request may optionally include an LPP positioning message. The eNodeB forwards the MO-LR Request (including any embedded LPP message) to the MME inside an S1AP Uplink NAS Transport message. Different types of location services can be requested: location estimate of the UE, location estimate of the UE to be sent to an external LCS client or location assistance data. If the UE is requesting its own location or that its own location be sent to an external LCS client, this message carries LCS requested QoS information (e.g. accuracy, response time, LCS QoS Class), the requested maximum age of location and the requested type of location (e.g. "current location", "current or last known location"). If the UE is requesting that its location be sent to an external LCS client, the message shall include the identity of the LCS client and may include the address of the GMLC through which the LCS client should be accessed. In addition, a Service Identity indicates which MO-LR service of the LCS Client is requested by the UE may be included. The message also may include a pseudonym indicator to indicate a pseudonym should be assigned by the network and transferred to the LCS Client as the UE's identity. If the UE is instead requesting location assistance data, the embedded LPP message specifies the type of assistance data and the positioning method for which the assistance data applies. For an LCS EPC-MO-LR requesting location transfer to an external LCS Client, the MME shall assign a GMLC address, i.e. V-GMLC address, which is stored in the MME. If a V-GMLC address is not available, the MME may reject the location request. The MME verifies the subscription profile of the UE and decides if the requested service is allowed or not.

The MME selects a E-SMLC as described in clause 6.3.13 and sends a Location Request message to the selected E-SMLC. The Location Request message conveys any embedded LPP message in the MO-LR Request. Once an MME has selected an E-SMLC it must continue to use that E-SMLC for the duration of the session. The Location Request message indicates whether a location estimate or location assistance data is requested. If the UE's location is requested, the message also includes the requested QoS. If location assistance data is requested, the embedded LPP message will convey the requested types of location assistance data. The message carries also other location parameters received in the MO-LR Request message, the current cell identity obtained from S1-AP message that carries the NAS MO-LR Request, and the UE capability to support LPP. The message also indicates RAT type and/or coverage level if applicable.

If the UE is requesting its own location, the actions described in clause 9.3a are performed. If the UE is instead requesting location assistance data, the E-SMLC transfers this data to the UE as described in clause 9.3a.1. The E-SMLC determines the exact location assistance data to transfer according to the type of data specified by the UE, the UE location capabilities and the current cell. NB-IoT UEs may perform measurements for some positioning methods only when in ECM-IDLE state. An E-SMLC that is aware of this (e.g. from an indication sent by the UE) may allow additional response time to the UE (e.g. in the QoS) to obtain the measurements. An MME that is aware of this (e.g. from the UE access type) may also allow additional time for a location session to complete.

When a location estimate best satisfying the requested QoS has been obtained or when the requested location assistance data has been transferred to the UE, the E-SMLC returns a Location Response to the MME with an indication whether the obtained location estimate satisfies the requested accuracy or not. This message carries the location estimate if this was obtained. If a location estimate was not successfully obtained, or if the requested location assistance data could not be transferred successfully to the UE, a failure cause is included in the Location Response.

If the UE did not request transfer of its location to an external LCS Client in step 2, steps 6 to 13 are skipped. Otherwise, if the location estimate was successfully obtained, the MME shall send a Subscriber Location Report to the V-GMLC assigned in the step 2, carrying the MSISDN/IMSI of the UE, the event causing the location estimate (EPC-MO LR) and the location estimate, its age, obtained accuracy indication and the LCS QoS Class requested by the target UE. In addition, the Subscriber Location Report may include the pseudonym indicator, the identity of the LCS Client, the GMLC address and the Service Identity specified by the UE, if available.

This step is the same as step 7 for a PS-MO-LR in clause 9.2.2.3.

This step is the same as step 8 for a PS-MO-LR in clause 9.2.2.3.

This step is the same as step 9 for a PS-MO-LR in clause 9.2.2.3.

This step is the same as step 10 for a PS-MO-LR in clause 9.2.2.3.

This step is the same as step 11 for a PS-MO-LR in clause 9.2.2.3.

This step is the same as step 12 for a PS-MO-LR in clause 9.2.2.3.

If the V-GMLC receives the MO-LR Location Information Acknowledgement from the H-GMLC, the V-GMLC shall record charging information both for the UE and inter-working revenue charges and send the Subscriber Location Report Acknowledgement to the MME, carrying the information specifies whether the location estimate of the UE has been handled successfully by the identified LCS Client, and if not success, the corresponding error cause obtained in step 12. If the V-GMLC receives the Subscriber Location Report from the MME and it is not required to send to any LCS Client, the V-GMLC shall record charging information for the UE and response the Subscriber Location Report Acknowledgement to the MME.

The MME returns a NAS MO-LR Response message to the UE carrying any location estimate requested by the UE including the indication received from E-SMLC whether the obtained location estimate satisfies the requested accuracy or not, or an indicator whether a location estimate was successfully transferred to the identified LCS client. If the location estimate was successfully transferred to the identified LCS Client, the MO-LR Response message shall specify whether the location estimate of the UE has been handled successfully by the identified LCS Client, and if not, the corresponding error cause obtained in step 13. The MME may record charging information.