5 Support of LCS signaling
24.1713GPPControl Plane Location Services (LCS) procedures in the Evolved Packet System (EPS)Release 17TS
5.1 General
This clause defines the E-UTRAN LCS operations (subclause 5.2) and the format and coding of the messages (subclause 5.3).
The messages defined in this subclause can be transported in the Downlink Generic NAS Transport message and the Uplink Generic NAS Transport message defined in 3GPP TS 24.301 [3].
5.2 LCS operations
5.2.0 General
The operations defined in this subclause are for E-UTRAN LCS support only.
The MO-LR operation and the Location Notification operation for E-UTRAN LCS are similar to that for GERAN and UTRAN LCS. The operations for GERAN and UTRAN location signalling support are defined in 24.030 [6].
5.2.1 Network initiated location services operations
5.2.1.1 Location Notification
5.2.1.1.0 General
The Location Notification operation enables the MME to trigger the end-user notification verification process on the UE using NAS signaling. The NAS signaling (see 5.2.1.1.1) are transported using the Downlink Generic NAS Transport message and the Uplink Generic NAS Transport message defined in 3GPP TS 24.301 [3]. Figure 5.2.1.1.0-1 illustrates an example of the NAS signaling transport for an EPC-MT-LR session.
Figure 5.2.1.1.0-1: NAS signaling transport for Location Notification
NOTE: The optional Additional Information IE of the Downlink/Uplink Generic NAS Transport message is not used when the LCS Location Notification signaling are transported in the Generic Message Container.
5.2.1.1.1 Normal operation
The network invokes a location notification procedure by sending a REGISTER message containing a LCS-LocationNotification invoke component to the UE. This may be sent either to request verification for MT-LR or to notify about already authorized MT-LR.
In case of privacy verification the UE shall respond to the request by sending a RELEASE COMPLETE message containing the mobile subscriber’s response in a return result component (see figure 5.2.1.1.1-1).
If the timer T(LCSN) expires in the network before any response from the UE (e.g. due to no response from the user), the network shall interpret this by applying the default treatment defined in TS 3GPP 23.271 [2] (i.e. disallow location if barred by subscription and allow location if allowed by subscription).
In the case of location notification no response is required from the UE, the UE shall terminate the dialogue by sending a RELEASE COMPLETE message containing a LocationNotification return result.
If the UE is unable to process the request received from the network, it shall return an error indication by sending a RELEASE COMPLETE message containing a return error component. Error values are specified in 3GPP TS 24.080 [5].
UE Network
REGISTER
<————————————————————————————————————————
Facility (Invoke = LCS-LocationNotification (notificationType, locationType, lcsClientExternalID, lcsClientName, lcsRequestorID, lcsCodeword, lcsServiceTypeId))
RELEASE COMPLETE
————————————————————————————————————————>
Facility (Return result = LCS-LocationNotification (verificationResponse))
RELEASE COMPLETE
– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – ->
Facility (Return error (Error))
RELEASE COMPLETE
– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – ->
Facility (Reject (Invoke_problem))
RELEASE COMPLETE
<- – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
Figure 5.2.1.1.1-1: Location Notification
5.2.1.2 Network initiated Positioning Information Transport
The MME sends LPP message and the associated Routing Identifier in the Downlink Generic NAS Transport message (Refer to 3GPP TS 24.301 [3]). Figure 5.2.1.2-1: illustrates an example of the NAS signaling transport for downlink LPP messages.
Figure 5.2.1.2-1: NAS signaling transport for downlink LPP messages
5.2.2 Mobile initiated location services operations
5.2.2.1 Mobile Originated Location Request (MO-LR)
5.2.2.1.0 General
The MO-LR operation enables the UE to launch MO positioning session using NAS signaling. The NAS signaling (see 5.2.2.1.1 and 5.2.2.1.2) are transported using the Downlink Generic NAS Transport message and the Uplink Generic NAS Transport message defined in 3GPP TS 24.301 [3]. Figure 5.2.2.1.0-1 illustrates an example of the NAS signaling transport for an EPC-MO-LR session.
Figure 5.2.2.1.0-1: NAS signaling transport for MO-LR
NOTE: The optional Additional Information of the Downlink/Uplink Generic NAS Transport message is not used when the MO-LR signaling are transported in the Generic Message Container.
5.2.2.1.1 Normal operation
The UE invokes a MO-LR by sending a REGISTER message to the network containing a LCS-MOLR invoke component. SS Version Indicator value 1 or above shall be used.
The receiving network entity shall initiate the handling of location request in the network. The network shall pass the result of the location procedure to the UE by sending a FACILITY message to the UE containing a LCS-MOLR return result component. When location estimate is kept in the network entity and this information satisfies the requested accuracy and the requested maximum age of location, then the network may reuse this information and the positioning measurement procedure may be skipped.
The network shall pass the result of the location procedure to the UE only if the location estimate is given in a format that the UE supports, as indicated by either the presence (and content) or the absence of the parameter supportedGADShapes, which may be sent by the UE in the LCS-MOLR operation.
The UE may terminate the dialogue by sending a RELEASE COMPLETE message in the case of single location request (see figure 5.2.2.1.1-1). The UE may also initiate another location request operation by sending a FACILITY message to the network containing a LCS-MOLR invoke component (see figure 5.2.2.1.1-2). After the last location request operation the UE shall terminate the dialogue by sending a RELEASE COMPLETE message.
If the network is unable to successfully fulfil the request received from the UE (e.g. to provide a location estimate or location assistance information), it shall clear the transaction by sending a RELEASE COMPLETE message containing a return error component. Error values are specified in 3GPP TS 24.080 [5]. If the network is unable to provide a location estimate due to lack of support in the UE for the type of shape of the location estimate, then it shall use the error Facility Not Supported.
If the network has returned a result to the UE in a FACILITY message but, after some PLMN administered time period has elapsed, has not received either a new location request operation in a FACILITY message or a RELEASE COMPLETE message from the UE, the network may clear the transaction by sending a RELEASE COMPLETE message.
During the MO-LR operation the UE shall run a timer T(LCSL). This timer is started when the operation is sent, and stopped when a response is received from the network. If this timer expires the UE shall assume that the operation has failed, and may terminate the dialogue by sending a RELEASE COMPLETE message, and shall inform the user of the failure.
UE Network
REGISTER
————————————————————————————————————————>
Facility (Invoke = LCS-MOLR (molr-Type, lcs-QoS, lcsClientExternalID, mlc-Number, supportedGADShapes, lcsServiceTypeID, ageOfLocationInfo, locationType, pseudonymIndicator, multiplePositioningProtocolPDUs))
FACILITY
<————————————————————————————————————————
Facility (Return result = LCS-MOLR (velocityEstimate, add-LocationEstimate))
RELEASE COMPLETE
<- – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
Facility (Return error (Error))
RELEASE COMPLETE
<- – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
Facility (Reject (Invoke_problem))
RELEASE COMPLETE
————————————————————————————————————————>
Figure 5.2.2.1.1-1: Single mobile originated location request
UE Network
REGISTER
————————————————————————————————————————>
Facility (Invoke = LCS-MOLR (molr-Type, lcs-QoS, lcsClientExternalID, mlc-Number, supportedGADShapes, lcsServiceTypeID, ageOfLocationInfo, locationType, pseudonymIndicator, multiplePositioningProtocolPDUs))
FACILITY
<————————————————————————————————————————
(Return result = LCS-MOLR (velocityEstimate, add-LocationEstimate))
RELEASE COMPLETE
<- – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
Facility (Return error (Error))
RELEASE COMPLETE
<- – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
Facility (Reject (Invoke_problem))
FACILITY
————————————————————————————————————————>
Facility (Invoke = LCS-MOLR (molr-Type, lcs-QoS, lcsClientExternalID, mlc-Number, supportedGADShapes, lcsServiceTypeID, ageOfLocationInfo, locationType, pseudonymIndicator, multiplePositioningProtocolPDUs))
FACILITY
<————————————————————————————————————————
(Return result = LCS-MOLR (velocityEstimate, add-LocationEstimate))
RELEASE COMPLETE
<- – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
Facility (Return error (Error))
RELEASE COMPLETE
<- – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
Facility (Reject (Invoke_problem))
RELEASE COMPLETE
————————————————————————————————————————>
Figure 5.2.2.1.1-2: Multiple mobile originated location requests
NOTE: Only the following IEs defined in MO-LR Invoke in 3GPP TS 24.080 [5] are used for E-UTRAN LCS:
– molr-Type
– lcs-QoS
– lcsServiceTypeID
– ageOfLocationInformation
– locationType
– mlc-Number
– lcsClientExternalID
– pseudonymIndicator
– supportedGADShapes
– multiplePositioningProtocolPDUs
NOTE: multiplePositioningProtocolPDUs IE is added to the LCS-MOLR Invoke to allow for passing multiple UE positioning information LPP messages (e.g. UE location measurements or UE capabilities) to the E-SMLC for E-UTRAN LCS. Its ASN.1 description is given in 3GPP TS 24.080 [5].
5.2.2.2 Mobile initiated Positioning Information Transport
The UE sends LPP message and the associated Routing Identifier in the Uplink Generic NAS Transport message (Refer to 3GPP TS 24.301 [3]). Figure 5.2.2.2-1 illustrates an example of the NAS signaling transport for uplink LPP messages.
Figure 5.2.2.2-1: NAS signaling transport for uplink LPP messages
5.3 LCS messages and coding
5.3.1 Messages for common LCS operations
The LCS message format and information elements coding for the MO-LR and the Location Notification operations (subclause 5.2) are defined in 24.080 [5] for the following messages:
– Register message
– Facility message
– Release Complete message
5.3.2 Messages for E-UTRAN LCS operations only
5.3.2.1 LPP Messages
5.3.2.1.1 Downlink Positioning Information Transport using LPP messages
The MME shall set the Generic Message Container Type to "LPP message container" in the Downlink Generic NAS Transport message.
The MME includes a Routing Identifier in the Additional Information IE of the Downlink Generic NAS Transport message associated with the positioning session between the MME and E-SMLC.
The Routing identifier is the Correlation ID, which is defined in 3GPP TS 29.171 [7], so that the MME can map the Routing identifier to the Correlation identifier when the MME receives an S1-AP Transport Message.
5.3.2.1.2 Uplink Positioning Information Transport using LPP messages
The UE shall set the Generic Message Container Type to "LPP message container" in the Uplink Generic NAS Transport message.
The UE includes a Routing Identifier received in the Additional Information IE of the Downlink Generic NAS Transport message in the the Additional Information IE of the Uplink Generic NAS Transport message. (See editor’s note below on Routing Identifier). This association of the Routing Identifier is provided at the LPP level: the UpLink Generic NAS Transport message carries an LPP message that is a response to or instigated by the LPP message in the Downlink Generic NAS Transport message.The Routing identifier is the Correlation ID, which is defined in 3GPP TS 29.171 [7], so that the MME can map the Routing identifier to the Correlation identifier when the MME receives an S1-AP Transport Message.
Annex A (informative):
Change history
Date |
TSG # |
TSG Doc. |
CR |
Rev |
Cat |
Subject/Comment |
New |
|
2010-03 |
CP#47 |
CP-100053 |
3GPP TS presented for approval in CT#47 |
9.0.0 |
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2011-03 |
– |
– |
– |
– |
Update to Rel-10 version (MCC) |
10.0.0 |
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2012-09 |
– |
– |
– |
– |
Update to Rel-11 version (MCC) |
11.0.0 |
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2014-09 |
– |
– |
– |
– |
Update to Rel-12 version (MCC) |
12.0.0 |
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2015-12 |
– |
– |
– |
– |
Update to Rel-13 version (MCC) |
13.0.0 |
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2017-03 |
– |
– |
– |
– |
Update to Rel-14 version (MCC) |
14.0.0 |
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2018-06 |
CT#80 |
– |
– |
– |
Update to Rel-15 version (MCC) |
15.0.0 |
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2020-07 |
CT#88e |
– |
– |
– |
Update to Rel-16 version (MCC) |
16.0.0 |
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2022-03 |
CT#95e |
– |
– |
– |
– |
Update to Rel-17 version (MCC) |
17.0.0 |