Multimedia Broadcast multicast service Single Frequency Network (MBSFN) is a

communication channel A communication channel refers either to a physical transmission medium such as a wire, or to a logical connection over a multiplexed medium such as a radio channel in telecommunications and computer networking. A channel is used for informa ...

defined in the fourth-generation cellular networking standard called Long-Term Evolution (LTE). The transmission mode is intended as a further improvement of the efficiency of the enhanced Multimedia Broadcast Multicast Service (eMBMS) service, which can deliver services such as

mobile TV Mobile television is television watched on a small handheld or mobile device. It includes service delivered via mobile phone networks, received free-to-air via terrestrial television stations, or via satellite broadcast. Regular broadcast stand ...

using the LTE infrastructure, and is expected to

compete Competition is a rivalry where two or more parties strive for a common goal which cannot be shared: where one's gain is the other's loss (an example of which is a zero-sum game). Competition can arise between entities such as organisms, indivi ...

with dedicated mobile/handheld TV broadcast systems such as

DVB-H DVB-H (Digital Video Broadcasting - Handheld) is one of three prevalent mobile TV formats. It is a technical specification for bringing broadcast services to mobile handsets. DVB-H was formally adopted as ETSI standard EN 302 304 in November 2 ...

and

DVB-SH DVB-SH ("Digital Video Broadcasting - Satellite services to Handhelds") is a physical layer standard for delivering IP based media content and data to handheld terminals such as mobile phones or PDAs, based on a hybrid satellite/terrestrial dow ...

. This enables

network operator A mobile network operator (MNO), also known as a wireless service provider, wireless carrier, cellular company, or mobile network carrier, is a provider of wireless communications services that owns or controls all the elements necessary to sell ...

s to offer mobile TV without the need for additional expensive licensed spectrum and without requiring new infrastructure and end-user devices. The eMBMS service can offer many more TV programs in a specific radio frequency spectrum as compared to traditional terrestrial TV broadcasting, since it is based on the principles of Interactive Multicast, where TV content only is transmitted in where there currently are viewers. The eMBMS service also provides better

system spectral efficiency Spectral efficiency, spectrum efficiency or bandwidth efficiency refers to the information rate that can be transmitted over a given bandwidth in a specific communication system. It is a measure of how efficiently a limited frequency spectrum is ut ...

than

video-on-demand Video on demand (VOD) is a media distribution system that allows users to access videos without a traditional video playback device and the constraints of a typical static broadcasting schedule. In the 20th century, broadcasting in the form of ...

over traditional cellular unicasting services, since in eMBMS, each TV program is only transmitted once in each cell, even if there are several viewers of that program in the same cell. The MBSFN transmission mode further improves the spectral efficiency, since it is based on the principles of

Dynamic single frequency networks {{Unreferenced, date=January 2008 Dynamic Single Frequency Networks (DSFN) is a transmitter macrodiversity technique for OFDM based cellular networks. DSFN is based on the idea of single frequency networks (SFN), which is a group of radio trans ...

(DSFN). This implies that it dynamically forms

single-frequency network A single-frequency network or SFN is a broadcast network where several transmitters simultaneously send the same signal over the same frequency channel. Analog AM and FM radio broadcast networks as well as digital broadcast networks can operate ...

s (SFNs), i.e. groups of adjacent base stations that send the same signal simultaneously on the same frequency sub-carriers, when there are mobile TV viewers of the same TV program content in the adjacent cells. The LTE

OFDMA Orthogonal frequency-division multiple access (OFDMA) is a multi-user version of the popular orthogonal frequency-division multiplexing (OFDM) digital modulation scheme. Multiple access is achieved in OFDMA by assigning subsets of subcarriers to ...

downlink modulation and multiple access scheme eliminates self-interference caused by the SFN:s. Efficient TV transmission using similar combinations of Interactive multicast (IP Multicast) and DSFN has also been suggested for the DVB-T2 and DVB-H systems.M. Eriksson, S.M. Hasibur Rahman, F. Fraille, M. Sjöström, �
Efficient Interactive Multicast over DVB-T2 - Utilizing Dynamic SFNs and PARPS
��, 2013 IEEE International Conference on Computer and Information Technology (BMSB’13), London, UK, June 2013. MBMS and

was a failure in 3G systems, and was offered by very few mobile operators, partly because of its limited peak bit rates and capacity, not allowing standard TV video quality, something that LTE with eMBMS does not suffer from.

Technical details

LTE's Enhanced Multimedia Broadcast Multicast Services (E-MBMS) provides transport features for sending the same content information to all the users in a cell (

broadcast Broadcasting is the distribution of audio or video content to a dispersed audience via any electronic mass communications medium, but typically one using the electromagnetic spectrum (radio waves), in a one-to-many model. Broadcasting began wi ...

) or to a given set of users (subscribers) in a cell (

multicast In computer networking, multicast is group communication where data transmission is addressed to a group of destination computers simultaneously. Multicast can be one-to-many or many-to-many distribution. Multicast should not be confused wi ...

) using a subset of the available radio resources with the remaining available to support transmissions towards a particular user (so-called

unicast Unicast is data transmission from a single sender (red) to a single receiver (green). Other devices on the network (yellow) do not participate in the communication. In computer networking, unicast is a one-to-one transmission from one point in ...

services). It must not be confused with IP-level broadcast or multicast, which offer no sharing of resources on the radio access level. In E-MBMS it is possible to either use a single eNode-B or multiple eNode-Bs for transmission to multiple UEs. MBSFN is the definition for the latter. MBSFN is a transmission mode which exploits LTE's

OFDM In telecommunications, orthogonal frequency-division multiplexing (OFDM) is a type of digital transmission and a method of encoding digital data on multiple carrier frequencies. OFDM has developed into a popular scheme for wideband digital commu ...

radio interface to send multicast or broadcast data as a multicell transmission over a synchronized single-frequency network (SFN). The transmissions from the multiple cells are sufficiently tightly synchronized for each to arrive at the UE within the OFDM Cyclic Prefix (CP) so as to avoid Inter-Symbol Interference (ISI). In effect, this makes the MBSFN transmission appear to a UE as a transmission from a single large cell, dramatically increasing the Signal-to-Interference Ratio (SIR) due to the absence of inter-cell interference.

Commercial adoption

Commercial deployment of E-MBMS (and therefore MBSFN) features is expected to start in 2013 as an upgrade of existing LTE networks. Lowell McAdam, CEO of Verizon, stated in his CES 2013 keynote that he hopes to have LTE-Broadcast available to live-broadcast the Super Bowl 2014 over its network. On a more general note, he identified live events as the ideal use case for LTE-Broadcast.

References

{{Reflist

External links

*3GPP specification
TS 36.201
an

*BP Tiwari
Is LTE capable of enabling new TV experience?
(BEYOND 4G: Telecom Research and News Analysis, June 4, 2010) *Santhanaraj Muthusamy
Solution Area: e-MBMS in LTE
(Teleca White Papers, February 2011)
LTE-based 5G Broadcast with larger SFN coverage
Wireless networking 3GPP standards Information theory Telecommunication theory Television terminology