LTE MBMS: How many sub frames of a radio frame are used to transmit multi/broadcast data ?

Question

I came to know total six subframes of a radio frame can be used for MBSFN transmission. How UE come to know about exact number of sub frames that are being used in a radio frame ? Does the eNodeB send this information to UE or UE itself figure out ?

Answer 1

Total 6 sub frames (Sub frame # 1,2,3, 6,7,8 ) of one radio frame are used to transmit multicast/broadcast data.

Comments

Hi Vimal, Is it mandatory to use all six sub frames always or It can be any number out of six ?

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Hello Rupam,

SIB2 informs either one radio frame or four consecutive radio frames will be used by one particular MBSFN Area. Since one cell can support up to eight MBSFN Areas, SIB2 can carry up to eight such configuration.

Maximum six sub frames of a radio frame can be used to provide MBMS services. Therefore one radio frame uses six bits and four consecutive radio frames use twenty four bits. If bit is set "1" for a sub frame then this will be used for MBMS transmission else it won't be used.

In essence, a particular sub frame of a radio frame would be used for MBMS if the corresponding bit is set "1" in MBSFN-SubframeConfig IE.
Hope this answer would help you !!!