PRACH size in LTE

[Mdaf]

Hi,
If we assume that we have disabled group B preambles (large size) and a UE has really big message to be sent, what will happen? Does it mean that the UE will distribute his PRACH on more PRACH RBs?

[wolverine]

It might have to, but by this stage the PRACH is not used anymore. Message 3 is sent using the PUSCH. The eNodeB provides a default uplink grant for this message. If it is not enough, the UE will indicate so in its BSR and get scheduled again in the next TTI.