Hi all,

My question is in regards to the initial access RACH procedure where we transmit msg1, msg2, msg3 and msg4.

My understanding is that this procedure is done to establish UE being in RRC connected mode such that it can receive RRC configurations

Does that mean before such procedure UE is not in RRC connected mode? If it is not, then how come some RACH configurations such as preamble configurations etc are assumed to be RRC configured before having the UE in RRC connected mode?

In general, RACH procedure is used to achieve uplink synchronization. It could be done in multiple cases. UE could be either idle or connected depending on the case.

For initial access, UE is in idle mode. UE gets RACH relevant info via system information (SIB2 in LTE and SIB1 in NR SA)

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Thank you very much