The ‟User Location Info” IE (as shown in Figure: User location information IE) can be included in create-pdp-context message as described in 3GPP TS 29.060 V10.1.0. The geographic location type field describes the type of location included in the ‟Geographic Location” field that follows. The location can be CGI (cell global identification), SAI (service area identity), or RAI (routing area identity). The formats for these location identifiers are defined in the same reference 3GPP TS 29.060 V10.1.0.
AP MAC address and SSID is reported to AAA (including changes on mobility). AAA can then specify the ULI IE contents based on static mapping of AP’s MAC address to one of the cellular location types (CGI, SAI or RAI). AAA should provide the cellular location in 3GPP attribute 3GPP-User-Location-Info (below) in access-accept. The attribute is described in 3GPP TS 29.061 v9.3.0.
In case a UE moves to a different WLAN-GW, UE is authenticated based on data-trigger. In this case, the AAA server can provide the WLAN location (AP’s MAC@ and SSID) in called-station-ID attribute and cellular location in 3GPP-User-Location-Info attribute. The WLAN location is then encoded in TWAN identifier in ‟create session request” message, and the cellular location is encoded in the ULI IE.