I read in 5G NR book that during RACH procedure, a UE transmits prach preamble associated with RA-RNTI. The gnb then upon reception calculates the RA-RNTI associated with prach occasion in which the preamble is transmitted.
My question is does the UE need to calculate the RA-RNTI before it transmits the preamble? Does it send it to the UE That is during Msg1? Or does it calculate it when it awaits random-access response from the gnb?