6 Functions of M2 interface for MBMS

36.4403GPPEvolved Universal Terrestrial Radio Access Network (E-UTRAN)General aspects and principles for interfaces supporting Multimedia Broadcast Multicast Service (MBMS) within E-UTRANRelease 17TS

6.1 General

“M2” Interface: MCE – eNB

An Application Part (M2AP) is defined in TS 36.443 [4] for this interface, which conveys at least radio configuration data for the multi-cell transmission mode eNBs and Session Control Signaling. SCTP (IETF RFC 4960 [10]) is used as signaling transport i.e. Point-to-Point signaling is applied.

6.2 M2 interface setup and configuration update functions

The M2 Setup (respectively the eNB and MCE configuration update) function allows to exchange (respectively update) application level data needed for the eNB and MCE to interoperate correctly on the M2 interface after the TNL association has become operational.

6.3 MBMS Session management function

MBMS session management function is responsible for starting, updating, and stopping MBMS sessions.

6.3.1 M2 service context management function

The M2 service context management function supports the establishment of the necessary overall initial service context including MBMS E-RAB context, M2 signalling connection ID(s), etc.

The establishment of the overall initial M2 service context is initiated by the MCE.

The M2 service context management function also supports the release of the context previously established in the eNB due to service termination. The release of the context is triggered by the MCE.

6.3.2 MBMS E-RAB management functions

The MBMS E-RAB service management function is responsible for establishing and releasing E-UTRAN resources for service data transport. The establishment of E-UTRAN resources is triggered by the MCE. The release of E-UTRAN resources is triggered by the MCE.

6.3.3 M2 link management function

The M2 signalling link management function provides a reliable transfer of the radio network signalling between eNBs and MCE. The SCTP is used to support the exchange of M2 Application Protocol (M2AP) signalling messages between eNBs and MCE.

6.3.4 MBMS Service Suspension and Resumption function

The MBMS Service Suspension function allows the MCE to request the eNB to stop the MBSFN transmission of an ongoing service and release associated RAN resouces while keeping the MBMS context in the eNB.

The MBMS Service Resumption function allows to resume a previously suspended MBMS Session.

6.4 MBMS Scheduling Information transfer function

This function provides multiplexing information if more than one MBMS service is active. The MCE allocates the amount of resources to multiplexed services, using service related information. The eNBs accept the MBMS Scheduling information to synchronize the MCCH transmission in the MBSFN area.

6.5 MBMS signalling synchronization over M2

The M2 interface shall support timing and synchronization management functions. MCE transmits the control information to eNBs through M2 interface. Synchronization function guarantees the corresponding MCCH to be transmitted at all eNBs simultaneously.

6.6 M2 interface reset and error processing function

These functions allow for managing of signalling associations between eNB-MCE, surveying M2 interface and recovering from errors.

6.6.1 Error indication

This function allows the reporting of general error situations on signalling exchange.

6.6.2 Reset

The reset function is used to initialize the peer entity after node setup or after a failure event occurred. The reset function may also be used to initialize part of the peer entity. This procedure can be used by both the eNB and MCE.

6.7 MBMS Counting Function

The MBMS Counting function allows the MCE to request the eNB(s) to count and report per MBSFN area for one or more MBMS services the number of connected UEs receiving the MBMS Service or interested in receiving it.