4 General
24.1713GPPControl Plane Location Services (LCS) procedures in the Evolved Packet System (EPS)Release 17TS
4.1 Overview
4.1.1 NAS aspect
To enable transfer of application protocol messages between the MME and the UE, a generic "container" message is defined on the downlink (Downlink Generic NAS Transport message) and the uplink (Uplink Generic NAS Transport message). The message protocol and procedures are described in 3GPP TS 24.301 [3].
4.1.2 LCS aspect
Location Services (LCS) uses the generic containers provided by the NAS Generic Transport mechanism to transfer LCS signalling messages between the UE and the network.
Currently, container in the generic transport messages can carry the following LCS information:
– LTE Positioning Protocol (LPP) messages (Refer to 3GPP TS 36.355 [4])
– Both downlink and uplink LPP messages are supported
– A Routing Identifier is transported as the Additional Information IE in Uplink/Downlink Generic NAS Transport message for LPP messages (Refer to 3GPP TS 24.301 [3])
– Location services messages
– Messages for MO-LR operations (Refer to 3GPP TS 24.080 [5])
– Messages for MT-LR LCS location notification (Refer to 3GPP TS 24.080 [5])
4.2 LCS Support capabilities
4.2.1 UE support of LCS
The UE announces to the network its ability to support LCS notification mechanism and/or LPP messages using the UE Network Capability IE defined in 3GPP TS 24.301 [3].
4.2.2 MME support of LCS
The network announces to the UE its ability to support LCS MO-LR mechanism in E-UTRAN and GERAN/UTRAN using the EPS network feature support IE defined in 3GPP TS 24.301[3]. These information are taken into account by the UE, in addition to UE’s LCS and CSFB capabilities for UE to determine whether to initiate EPC-MO-LR procedure or CS fallback procedure for CS-MO-LR in GERAN/UTRAN as specified in 3GPP TS 23.272 [8], subclause 8.3.1.