UMTS: Alive and Well - 4G Americas

6.2.5 MBMS FOR LTE6.2.5.1 OVERVIEWThis section describes the architectural model and functionalities for the MultimediaBroadcast/Multicast Service (MBMS) Bearer Service and is based on 3GPP TS 23.246. In caseof discrepancies in other parts of the 3GPP specifications related to MBMS, 3GPP TS 23.246takes precedence. MBMS Bearer Service is the service provided by the packet-switched domainto MBMS User Services to deliver IP Multicast datagrams to multiple receivers using minimumnetwork and radio resources. An MBMS User Service is an MBMS service provided to the enduserby means of the MBMS Bearer Service and possibly other capabilities, such as EPSBearers.MBMS is a point-to-multipoint service in which data is transmitted from a single source entity tomultiple recipients. Transmitting the same data to multiple recipients allows the sharing ofnetwork resources. The MBMS for EPS bearer service supports Broadcast Mode over E-UTRANand UTRAN. (MBMS for GPRS supports both Broadcast Mode and Multicast Mode over UTRANand GERAN).MBMS is realized by the addition of a number of new capabilities to existing functional entities ofthe 3GPP architecture and by addition of several new functional entities. In the bearer plane, thisservice provides delivery of IP Multicast datagrams from the SGi-mb reference point to UEs. Inthe control plane, this service provides mechanisms to control session initiation, modification andtermination of MBMS User Services and to manage bearer resources for the distribution ofMBMS data.The reference architecture for the MBMS Bearer Service for EPS is shown in Figure 6.5 below.6.2.5.2 MBMS REFERENCE ARCHITECTURE MODELE-UTRAN UuUEE-UTRANM3M1MMESmMBMSGWPDNGatewaySGiSGmbBM-SCSGi-mbContent ProviderUEUuUTRANIuSGSNSnFigure 6.5. Reference Architecture for MBMS for EPS with E-UTRAN and UTRAN. 105NOTE: In addition to MBMS Bearers (over SGmb/SGi-mb), the BM-SC may use EPS Bearers(over SGi) to realize an MBMS User Service as specified in 3GPP TS 26.346.105 3GPP TS 23.246 Figure 1b.www.3GAmericas.org February 2010 Page 63