Multicast-broadcast single-frequency network: Difference between revisions

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==Technical details==

LTE's Enhanced [[MBMS|Multimedia Broadcast Multicast Services]] (E-MBMS) provides transport features for sending the same content information to all the users in a cell ([[broadcast]]) or to a given set of users (subscribers) in a cell ([[multicast]]) using a subset of the available radio resources with the remaining available to support transmissions towards a particular user (so-called [[unicast]] 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 [[Node B|eNode-B]] or multiple eNode-Bs for transmission to multiple [[User equipment|UE]]s. MBSFN is the definition for the latter.<ref name=Lescuyer>{{cite book|last=Lescuyer|first=Pierre|title=Evolved Packet System (EPS): The LTE and SAE Evolution of 3G UMTS|year=2008|publisher=Wiley|isbn=978-0-470-05976-0|pages=350|pages=140–143|url=http://www.wiley.com/WileyCDA/WileyTitle/productCd-0470059761.html}}</ref>

MBSFN is a transmission mode which exploits LTE's [[OFDM]] radio interface to send multicast or broadcast data as a multicell transmission over a synchronized [[Single-frequency network|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|Cyclic Prefix (CP)]] so as to avoid [[Intersymbol interference|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|Signal-to-Interference Ratio (SIR)]] due to the absence of inter-cell interference.<ref name=Sesia>{{cite book|last=Sesia|first=Stefania|title=LTE - A Pocket Dictionary of Acronyms|year=2009|publisher=Wiley|isbn=978-0-470-69716-0|page=45|url=http://lte.alcatel-lucent.com/locale/en_us/downloads/LTE-A_Pocket_Dictionary_of_Acronyms.pdf}}</ref>