check this white paper
http://www.ericsson.com/res/docs/whitepapers/wp-lte-broadcast.pdf
LTE Broadcast is a single-frequency network (SFN) in broadcast mode that is part of the series of 3GPP LTE standards known as evolved Multimedia Broadcast Multicast Service (eMBMS). It extends existing LTE/Evolved Packet Core (EPC) systems with an efficient point-to-multipoint (PMP) distribution feature, enabling multiple users to receive the same content simultaneously.
LTE Broadcast functionality is available for commercial launch, beginning with Release 9 and with additional enhancements continuing in future 3GPP releases. LTE Broadcast is supported for all defined bandwidths and formats of LTE, including FDD, TDD, and carrier aggregation (CA). SFN technology is used to distribute broadcast streams into well-defined broadcast areas where all cells contributing to an SFN send the same data during exactly the same radio timeslots and appear as a single large cell. The area covered by the LTE SFNs can be small, spanning just a few cells; or it can be very large, covering an entire country. Broadcast and unicast radio channels coexist in the same cell, sharing capacity, while the subsets of available radio resources are dynamically assigned to either broadcast or unicast radio channels.
The LTE network can be upgraded by software, and a new media service layer offers a dedicated network element for the implementation of end-to-end LTE Broadcast services. LTE Broadcast provides a more flexible and lower deployment cost compared with previous mobile-broadcast options by leveraging OFDMA (Orthogonal Frequency-Division Multiple Access) and wider bandwidths available in LTE. On user devices, LTE Broadcast requires no separate device chipset and can use common middleware.
LTE Broadcast offers the greatest benefits in the delivery of content demanded by mass audiences. The technology starts to provide network-capacity advantages over unicast in a cell with as few as one to four concurrent users, depending on the deployment characteristics.
LTE Broadcast’s flexible service dynamics allow MNOs to offer different services based on service type (live or non-real time), location (venue-specific, local, regional, national), quality (bitrate, QoS), and time of day/duration, and, as a result, charge differently for these.
