Remove the secondaryCellGroup variable in RRC, as it is not used there.
Note that in the case of F1, the secondaryCellGroup entirely belongs to
the DU, i.e., MAC. Also, we don't do anything with it in RRC.
Variable spCellConfig is only used in function rrc_add_nsa_user(). Make
it local to this function to prevent possible bugs (limit the possible
scope as much as possible).
Variable reconfig is only used in function rrc_add_nsa_user(). Make it
local to this function to prevent possible bugs (limit the possible
scope as much as possible).
- neighbour_config.conf file includes neighbour and measurement related parameters
Neighbour List:
- nr_cellid: the identity of existing cell who has neighbour
- neighbour_cell_configuration(list): includes the identity parameters
of the neighbour cell such:
- gNBID (incase of N2 Handover / to be identified from AMF)
- nr_cell_id (target gNB needs to consider)
- physical_cellId (needed for measurement reporting)
- absoluteFrequencySSB (needed for measurement reporting)
- subcarrierSpacing (needed for measurement reporting)
- plmn / tracking area code (incase of N2 Handover / needed for AMF
to identify / allow HO)
NR Measurement Configuration
- Periodical
- enable (default is 0, 1 enables the reporting)
- includeBeamMeasurements, maxNrOfRS_IndexesToReport (configurable
reporting parameters)
- A2
- enable (default is 0, 1 enables the reporting)
- threshold , timeToTrigger (configurable reporting parameters)
- A3
- cell_id (the nr_cellid of neighbour cell. So this A3 parameters
will be used for the neighbour
- [-1] means default. so it can be applied to any neighbour if
there is no specific config
- Neighbour specific A3 Threshold can be used or default can be
selected depending to the neighbour planning
- The neighbour-config.conf specifies, apply default A3 for
neighbours 3 and 4 | apply specific one for neighbour 2
- offset, hysteresis, timeToTrigger (configurable reporting parameters)
the neighbour_config.conf can be included in the gNB.conf file. Example
is given: gnb.sa.band78.106prb.rfsim.neighbour.conf
A sequence array container is used for neighbour cell configuration. RRC
structure has this container. A Measurement configuration structure is
defined. This structure has Periodical / A2 Event structures and also a
sequence container for A3 Event List.
These structures are filled during the initialization. While F1 Setup
Response is coming from DU to CU, the intra frequency / inter frequency
neighbour decision is given for the existing cell. Also new neighbours
could be added here if needed.
The starting point was the function do_NR_DLInformationTransfer() which
may deal with more than 256 bytes.
Then why not cleanup all the functions in the same file.
(And do a bit of formattting fixing while we're here.)
Then cleanup the callers of those functions.
Then, because of do_SIB23_NR() let's also cleanup in some
structures.
Not all the codebase was cleaned up, there surely remain some uint8_t
(and char/short/uint16_t) which are wrong.
In the case of PDU sessions in the NG UE context setup request, we first
have to set up security. Hence, in this commit, implement the "delayed"
set up of theses PDU sessions, and acknowledge the setup request after
reconfiguration, as requested by O-RAN.WG5.C.1-v11.
Trigger UE ctxt setup response for the case of "registration request"
(no PDU sessions in UE Context setup response), as mandated by
O-RAN.WG5.C.1-v11.
This reverts commit 0f100a6e94, which
introduced a hack to possibly wait with a PDU session setup at the RRC
in case a RRC UE capability transaction (requesting UE capabilities from
a UE) was ongoing. This happened, as we delayed the UE capabilities to
after the first RRC reconfiguration; in that case, certain UEs were
requesting the next PDU session, and if RRC did not delay the new PDU
session (as requested from the core), this procedure might occur while
UE capability enquiry was ongoing, leading to failures in these
transactions.
- according to specs, in NR there are 4 SRBs
- in OAI the relevant define is used in the RRC procedures
- this commit harmonizes code by removing redundancy
The next commit moves the UE Capability Enquiry after the first
reconfiguration. This has the effect that for some UEs (e.g., iPhone),
the Setup Requests come too close to each other, triggering RRC
Reconfigurations while previous transactions are ongoing.
I think the "true" solution would be to implement some tracking of
transactions across RRC, F1AP, E1AP, but this might require many
changes. For the moment, limit to delaying PDU session resource setups
to prevent above problem. Delaying is done using ITTI timers (to be able
to serve other UEs), waiting 10ms each time, up to 20 times (to not
deadlock the transaction -- after all, if the UE is unhappy, it will
drop the connection).
The function rrc_gNB_process_RRCReconfigurationComplete() does almost
nothing, we can delete it.
The variable name ue_reconfiguration_after_reestablishment_counter is
misleading, as it counts all reconfigurations; rename to make it clear.
The drb_active array keeps track of active DRBs. However, it only
replicates some of the information in established_drbs, and could lead
to a reuse of DRB IDs when two bearers are to be set up. Consider the
following:
1. trigger first DRB creation at RRC
2. DRB ID chosen from free drb_active entry
3. trigger second DRB creation at RRC
-> The first reconfiguration has not been acknowledged
-> drb_active is not marked as DRB_ACTIVE
4. The second DRB ID is chosen from a free drb_active entry, which is
the same as in 2.
By reusing established_drbs everywhere, this cannot happen, as we
1. select the DRB to be used using next_available_drb() and then
2. use generateDRB(), which marks the DRB used
all from within fill_DRB_configList, which gives a new DRB.
The logic is still overly complex, though.
This commit implements retrieval of 5G-S-TMSI from Parts 1&2, or the
entire 5G-S-TMSI, depending on what the UE sends. Further, if it has
been retrieved, print a log of all constituent parts of it.
The UE-specific variable ng_5G_S_TMSI_Part2 is not needed, as we compute
the full 5G-S-TMSI as soon as we have Part2 (and 1).
The correct forwarding to the core is implemented in the following
commit.
Keeping track if AS security is activated. This is important for a later
commit, where we use this to decide if we send a F1 UE Context Setup Req
with security command after receiving the E1 bearer context setup
response. The corresponding AssertFatal() removed in the same commit
implementing PDU session handling in NGAP Initial UE Context Setup.
remove several unused files
remove mem_block_t that is never used in a different way than a simple heap buffer
move up IP address type and remove duplications of the same struct declaration
This commit introduces the capability to handle multiple CU-UPs. It uses
a RB tree and puts the CU-UPs into the tree. Upon the connection, it
associates UEs to CU-UPs in a round-robin fashion.
- 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
The MasterInformationBlock is handled at the DU and sent to the CU in
the F1 Setup Response. Hence, move it down to the MAC. Furthermore:
- Change type because MIB_PDU_t is 4G type
- Simplify schedule_nr_mib()
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.
- send F1 Setup using callback
- store f1 setup req locally for reference
- check F1 Setup Req against RRC data structures:
* if matches: send F1 Setup Response using callback
* if not matching: send F1 Setup Failure using callback
- don't send CU config update by default, we don't need this
- if the Setup Response does not contain a cell, don't activate. It is
possible the CU sends a gNB-CU configuration update, which will
initialize the structures
This commit repairs the reestablishment after the introduction of the CU
UE ID in the CU, different from the DU UE ID. Now, the CU uses an
identifier different from the RNTI, used in the MAC, to refer to UEs.
To repair the reestablishment, a number of changes needed to be
introduced:
- Handle old_gNB_DU_UE_id in MAC
The MAC handles the old_gNB_DU_UE_id field in the DL RRC Message. The
commit adds encoding/decoding of the field. The MAC will drop the old
UE, but retain the CellGroup of the corresponding UE(!). Because a UE
releases the spCellGroup on reestablishment, the MAC does the same; it
needs to reapply the old configuration after a reconfiguration. For the
latter, introduce new variables to keep a "future" CellGroupConfig to be
applied (reconfigCellGroup) and a flag (expect_reconfiguration) that
applies the CellGroupConfig if a DL RRC Message transfer on DCCH, which
is assumed to be the reconfiguration.
- Add RNTI change in RLC
The RLC needs to reuse the old UE context. Hence, we simply change the
RNTI in the old context, and delete the new one.
- No PDCP UE ID change
The previous implementation of the PDCP used the RNTI; hence, the ID
needed to be switch (as above for the RLC). Since the PDCP now also uses
the CU UE ID, no identifier change is needed, and we remove all
corresponding code.
- No MAC modifications/update from CU
As foreseen by the spec, the CU does not modify or change the
cellGroupConfig in the RRC during reestablishment. This change will be
generalized in the future to all of the RRC. Also, the
nr_rrc_mac_remove_ue() function has been removed: the MAC handles any UE
changes autonomeously, without being triggered from the RRC explicitly.
- Remove reestablish_rnti_map
The RRC does not use RNTIs for UE identification. Hence, a
reestablish_rnti_map to link two UEs to each other is not necessary
anymore.
Xin Zhe Khooi