Use F1 internally: UE Context Modification
Third MR to use the F1 UE Context messages internally at the gNB (even in monolithic). Based on and to be merged after !2101 (merged)
Changes:
- Use UE Context modification internally, i.e., for dedicated RRC reconfiguration (but not yet for other possible messages, e.g., PDU session management. I can add if you want)
- Send RRC reconfiguration status via UE Context modification, even though the DU does not use it
- Remove per-UE RRC information at the DU (hopefully RRC UE message handling at the DU will now result in a segfault)
See f1.pcapng: it seems to me this is much closer to what we have with Accelleran
I planned on adding QoS but I don't have all information yet for that, so probably we do it later, and the MR is big enough. Other next steps:
- handle separate DU and CU UE IDs, and remove the RNTI from internal F1 message structs (towards multi-DU operation). I believe I can make reestablishment functional over F1 here
- QoS, in some form, to set up multiple bearers
- UE Capability handling: send UE Capabilities to DU, handle CellGroupConfig completely at the DU.