eams There is also a specification for evolved MBMS (eMBMS), which uses MBMS over LTE and is also referred to as LTE Broadcast. One of the major differences between MBMS and eMBMS is that eMBMS allows dynamic network resource allocation. For example, an operator can choose to dedicate its network capacity in a specific MBSFN area to broadcast a specific event, and once the event is over, it can reallocate those resources back to regular traffic. With MBMS based on MBSFN, the timing alignment must be accurate to within few microseconds to ensure that the signals from multiple cells appear as signals from a single cell. Hence, all trans- missions require a tight synchronization at the eNB or BS level; that accuracy requirement is out- lined in Table 10-9. Table 10-9 Time Synchronization Requirement for MBSFN LTE MBSFN Time Alignment Error Reference Cell phase synchronization accuracy at the BS antenna connectors TS 36.133 10.3.1 Positioning Positioning refers to functionality in the RAN that allows it to determine the location of the UE. Most UEs now have an embedded GNSS receiver to provide tracking and positioning data and to enable location-based services. However, there are conditions where either the GNSS service is not available (indoors) or the UE itself does not have a GNSS receiver (such as small IOT sensors). Hence, in 3GPP Release 9, positioning support is introduced into the RAN with the LTE Position- ing Protocol (LPP). This technique can determine the location of the UE by taking measurements using special reference signals transmitted regularly from several cell sites. The technique used to do this is known as the Observed Time Difference of Arrival (OTDOA). The UE measures the time difference between the arrival times of special reference signals sent from a minimum of three eNBs and reports these time differences to a specific device in the network. The key entity in the mobile core network that handles positioning is the Evolved Serving Mobile Location Center (E-SMLC). The E-SMLC is responsible fo