Evolved Universal Terrestrial Radio Access Network (E-UTRAN); S1 Application Protocol (S1AP) Status: Under change control: Type: Technical specification (TS) Initial planned Release: Release 8: Internal: Common IMS Specification: Radio technology: 2G: 3G: LTE: 5G: 6G: Click to see all versions of this specification: Remarks (0)

The present document may refer to technical specifications or reports using their 3GPP identities, UMTS identities or GSM identities. These should be interpreted as being references to the corresponding ETSI deliverables.

S1AP provides the signalling service between E-UTRAN and the evolved packet core (EPC) and has following functions: 3GPP TS 36.413 - Evolved Universal Terrestrial Radio Access Network (E-UTRAN); S1 Application Protocol (S1AP)

This 3GPP document specifies the E-UTRAN radio network layer signalling protocol for the S1 interface.

S1AP is also responsible for carrying the messaging that enables the E-RAB ‘path switch’ function to take place after an inter-eNB handover. Additionally, it provides support for MME relocation and S-GW change functions. S1AP is an evolution of the RANAP protocol employed in 3G networks. Further Reading: 3GPP TS 36.41x series, 36.413 (S1AP)

S1 Application Protocol (S1AP) (Release 10) The present document has been developed within the 3 rd Generation Partnership Project (3GPP TM ) and may be further elaborated for the purposes of 3GPP.

In the following tables, all EPs are divided into Class 1 and Class 2 EPs (see subclause 3.1 for explanation of the different classes): Table 1: Class 1 procedures. Table 2: Class 2 procedures. The following applies concerning interference between Elementary Procedures: – The Reset procedure takes precedence over all other EPs.

The S1 Setup procedure is used to exchange configured data which is required in the MME and in the eNB respectively to ensure a proper interoperation. The S1 Setup procedure is triggered by the eNB. The S1 Setup procedure is the first S1AP procedure which will be executed. Figure 19.2.2.8-1: S1 Setup procedure

This Technical Specification (TS) has been produced by ETSI 3rd Generation Partnership Project (3GPP). The present document may refer to technical specifications or reports using their 3GPP identities, UMTS identities or

The S1AP protocol has the following functions: – E-RAB management function: This overall functionality is responsible for setting up, modifying and releasing E-RABs, which are triggered by the MME. The release and modification of E-RABs may be triggered by the eNB as well.