Multimedia Broadcast Multicast Service is a service in the UMTS mobile phone standard, capable of transmitting multimedia data, such as mobile TV or files to many users simultaneously and efficiently. The data stream is sent individually to each user, which significantly lowers network load because the data is sent only once. This results in savings in both the radio network (Radio Access Network – RAN) as well as in the transmission network, in which IP multicast can be used.
MBMS offers two transmission modes: broadcast: UMTS MBMS reception and multicast reception of services that do require authentication.
For both modes, the wireless network can identify the user density per cell and select the type of radio bearer (point-to-point or point-to-multipoint support). With few users, point-to-point is (conventionally or via HSDPA) efficient because optimization mechanisms such as power control can be used while for many users the point-to-multipoint transmission is cheaper because the signal is sent only once and can handle unlimited number of users.
The ability to select the carrier in broadcast mode was added late in the Release 6 to enable the elimination of the multicast procedures. It can change faster between television channels while enabling efficient transmission in the radio network. Both methods support encryption so that both free and fee-based services with two modes are possible.
MBMS is different from other methods that offer Mobile TV, such as DVB-H or DMB, in that the data is not transmitted via its own frequencies and channels similar to classic television but over UMTS. This has the advantage that it needs additional frequencies and establish a new network infrastructure for mobile operators. In addition, the services in geographically limited areas can be offered (cell-based), such as special channels in football stadiums. MBMS is not limited to video transmission, but also offers the possibility to distribute files (eg podcasts) to many users.
A disadvantage of the use of MBMS for mobile TV is the relatively low number of simultaneously transmitted television channels (four to eight point-to-multipoint transmissions per 5 MHz carrier), wherein a large portion of the cell capacity for MBMS services used . However, only the channels in a cell must be sent.
MBMS is part of the UMTS specification of Release 6, which is largely completed in the 3GPP standardization body. It is in the context of 3GPP Long Term Evolution (LTE) and System Architecture Evolution (SAE) expanded.
GMR-1 offered by Radio Broadcasting Equipment Suppliers leans heavily on GSM. The transmission protocol differs only in the lowest three OSI layers, for GmPRS only the lowest two. Specialized features include terminal-to-terminal.
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