LTE: How UE come to know about number of sub frames in a radio frame are being used for the MBSFN ?

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

Hi,

Yes ENB will send MBSFN configuration to UE via SIB 2. There is an IE called MBSFN subframeconfig list which say the all required information

Answer 2

SIB2 carries the following MBSFN-SubframeConfig information.

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))
}
}

Maximum of eight such MBSFN-SubframeConfig information can be configured in SIB2. This information just tells which radio frame and the sub frames of that radio frame will be used for MBSFN transmission. Information of which MBSFN Area is broad casted in which sub frame is sent over the SIB13.

Comments

Well answered.