1 - UE sends RRC setup message with “ng-5G-S-TMSI-Part1”; my first worry is if the network would reject this RRC; it sends RRC reject with no UE identity; how did UE obtain this message to himself?
2- Additionally, all dedicated messages are sent without UE identity, raising the same question. So, how did UE receive this message?
3- If the UE establishes a PDU session and wants to add another Qos-Flow, it will send an RRC setup request through the -UL-DCCH-Message?
4- What is the distinction between the -UL-CCCH1-Message and the -UL-CCCH-Message?
1 - In Msg4 there is a MAC CE including UE Contention Resolution Identity that matches the one in Msg3 CCCH SDU, then the UE knows the Msg4 is for itself.
2 - After contention resolution UE gets a temporary identity C-RNTI, which is valid in the current cell only. C-RNTI is used in PDCCH scrambling and differ to other UE’s C-RNTI. Different UE’s PDCCH schedules different PDSCH, then UE can only receive its own message.
3 - PDU session establishment is session related procedure, no relation with RRC procedure. And a UE can maintain only one RRC connection at the same time.
4 - UL-CCCH1-Message carries 64 bits while UL-CCCH-Message carries 48 bits.