LTE: Tracking Area Update Accept

If the TRACKING AREA UPDATE REQUEST has been accepted by the network, the MME shall send a TRACKING AREA UPDATE ACCEPT message to the UE. Some of the IEs included in this message are explained below

If the MME assigns a new GUTI for the UE, a GUTI shall be included in the TRACKING AREA UPDATE ACCEPT message. The UE shall use this GUTI as new temporary identity for EPS services and shall store the new GUTI. If no GUTI was included by the MME in the TRACKING AREA UPDATE ACCEPT message, the old GUTI shall be used. Same is the case with IE TAI list

The purpose of the EPS update result IE is to specify the result of tracking area updating procedure. It could result in ‘TA updated’ or ‘combined TA/LA updated’ or ‘TA updated and ISR activated’ or ‘combined TA/LA updated and ISR activated’

If the EPS bearer context status IE is included in the TRACKING AREA UPDATE REQUEST, the MME shall include an EPS bearer context status IE in the TRACKING AREA UPDATE ACCEPT message, indicating which EPS bearer contexts are active in the MME. The UE shall deactivate all those EPS bearers contexts locally (without peer-to-peer signalling between the UE and the MME) which are active in the UE, but are indicated by the MME as being inactive

The MME may also include of list of equivalent PLMNs in the TRACKING AREA UPDATE ACCEPT message. Each entry in the list contains a PLMN code (MCC+MNC)

The MME includes EMM Cause IE if the combined tracking area updating procedure was successful for EPS services only

The purpose of the EPS network feature support IE is to indicate whether certain features are supported by the network. It can indicate the following features whether supported or not: IMS voice over PS session indicator (IMS VoPS), Emergency bearer services indicator (EMC BS), Location services indicator in EPC (EPC-LCS), Location services indicator in CS (CS-LCS), Support of EXTENDED SERVICE REQUEST for packet services (ESRPS)

The purpose of the Additional update result IE is to provide additional information about the result of a combined tracking area updating procedure. It indicates if the procedure was successful for “EPS services and non-EPS services”, or for “EPS services” and "SMS only"

Reference: 3GPP TS 24301

Example: TRACKING AREA UPDATE ACCEPT