3GPP has the concept of a gNB-CU-UP ID and a (separate) gNB ID (for gNB,
CU-CP). This commit introduces the gNB-CU-UP as a separate ID that has to be
set in the configuration file when running as a CU-UP. For the
CU/monolithic gNB, it is optional (but needs to be the same as the
gNB-ID if specified).
The CU-UP ID is necessary, as some entities, e.g., the e2 agent, need to
signal both IDs, e.g., to reconcile a CU-CP and (multiple) CU-UP(s)
belonging together.
The E1AP Setup Request contained the network configuration (IP address,
ports) as well as the actual E1AP Setup Request application data
(Supported PLMNs, ...). This has the drawbacks that
- The E1AP Setup Request is stored to retrieve IP addresses in the E1AP
module, which is confusing as the Setup Request, per standard, has no IP
info
- The CU-CP received an E1 Setup Request for configuration during start
up, but it did not actually receive such Setup Request, but merely the
IP configuration to set up the socket
This commit splits the E1AP Setup Request into a "real" Setup Request
for application data, and creates a new type e1ap_net_config_t to group
all IP configuration data. Further, a new ITTI message type
E1AP_REGISTER_REQ is introduced to group both types. What happens is
- RCconfig_NR_CU_E1() reads both E1AP application-level data and IP
configuration, as previously
- The data is sent to the CU-CP. It discards the E1AP Setup Request
data, and only uses the network configuration to set up the socket
- The data is sent to the CU-UP. It uses the network configuration to
connect to the CU-CP, and then sends the E1AP Setup Request to the
CU-CP.
Currently, the CU-CP still stores the Setup Request locally, which will
be changed in the next commit to send it to the RRC.
The DRBLists inside E1AP message are for E-UTRAN. We don't support that
with our CU-CP/UP yet, so remove it to reduce ambiguity and complexity.
For the same reason, we remove the CN Support, which for us is always
"NR".
- store the assoc ID of a UE at the RRC
- if F1 receives an SCTP shutdown, it removes the endpoint
- F1 will also send an "F1 Lost Connection" message to the RRC
- it is not yet possible to reconnect a DU after it had already been
connected at the CU, since the CU F1AP task will try to rebind GTP,
which fails
!SIB1 is not correctly filled! This commit does not work with COTS UEs!
The next commit fixes this.
- Move radio config (e.g., minRXTXTIME, SIB1 TDA, do_SRS, etc) down to
MAC.
- Some parameters in MAC are redundant: delete them.
- Remove call to nr_mac_config_scc() from RRC and simulators, the MAC
initialization routine calls it implicitly
Note: the reestablishment is broken, and a later commit fixes it.
The ServingCellConfigCommon is an inherently radio-related
configuration. As such, it should be handled by the DU, not the CU.
Therefore, move it "down" to the MAC.
Use a struct to initialize the RRC at the beginning, and remove the
NRRRC_CONFIGURATION_REQ. This message is not necessary; the RRC/CU
should be initialized from the F1 Setup Request, coming from the DU.
This branch series implements the usage of the F1 Setup Request
internally at the gNB, even if CU and DU run in the same process. Until
now, the F1 Setup Request contained struct fields to pass IP
configuration to the F1AP module; this information is not necessary in
monolithic, nor should it be relevant when passing the information in
F1 Setup Request.
Therefore, this commit moves all IP connection-related information out
of the F1 Setup Request and into a separate structure instead. In order
to give the F1AP module the necessary connection information, the
DU_REGISTER_REQ message is introduced that combines the F1 Setup Request
and IP configuration, such that the F1AP module can setup the SCTP
connection and then send the F1 Setup Request message.
In a later commit, there will be a callback for F1 Setup Request at MAC
to simply register the DU at the CU. The monolithic callback will simply
forward the F1 Setup Request The F1AP callback will look up the IP
configuration and create DU_REGISTER_REQ message containing IP
configuration and F1 Setup Request, which is then handled by the F1AP
module. To this end, a separate function in gnb_config.c allows to read
IP information from configuration.
- Use the same CU-UP in E1 as in CU-CP: we don't have a separate entity
to allocate IDs, and we just use the same as the CU-CP
- Correct gNB CU-UP/CP UE IDs in E1AP message types to 32bit
- Set CU UP UE ID explicitly for clarity
- Remove RNTI from E1 messages, E1 does not know what an RNTI is
- The CU/DU UE ID is used in DL RRC Message Transfer
- Note: The CU UE ID currently is still the RNTI
- on every DL RRC Message, the DU verifies that the UE exists
- Refactor RRC: common function to forward protected SRB PDUs
Robert Schmidt