LTE MBMS: How an UE get to know about MBMS resource location over the spectrum ?

Question

N numbers of UEs can be scheduled at a particular TTI. So How does an UE get to know its own DCI ?

Answer 1

MCCH channel carries "MBSFNAreaConfiguration" IE which in turn contains "MBSFN-SubframeConfig" information. This "MBFSN-SubframeConfig"

MBSFN-SubframeConfig ::=            SEQUENCE {
    radioframeAllocationPeriod          ENUMERATED {n1, n2, n4, n8, n16, n32},
    radioframeAllocationOffset          INTEGER (0..7),
    subframeAllocation                  CHOICE {
        oneFrame                            BIT STRING (SIZE(6)),
        fourFrames                          BIT STRING (SIZE(24))
    }
}

MBMS data is allocated over the one radio frame or contiguous four radio frames. As we know, only 6 subframes of one radio frame can carry MBMB data. So Max 24 sub frames can carry data. Reason being, 24 bit map is used to inform to UE about the location of MBMS data. Sometimes a subset of 24 subframes may used. In that case, the subframe which is not being used to carry MBMS data, corresponding bit in the bit map is marked as '0'.