In rrc_gNB_NGAP.c, rrc_gNB_process_Handover_Request() is updated to
resolve the target by cell instead of by DU, then resolve the DU from
the cell's assoc_id. This aligns Handover Request with the new
cell-centric model and cell management APIs.
- Resolve target with get_cell_by_cell_id(&rrc->cells, msg->nr_cell_id)
instead of get_du_by_cell_id(); on failure, log "no cell found" and
send NGAP handover failure.
- Resolve DU with get_du_by_assoc_id(rrc, cell->assoc_id); add a
failure path (log, NGAP handover failure, return -1) when no DU
exists for the cell's assoc_id.
- Use cell->info (nr_rrc_cell_info_t) for logging and for key
derivation (nr_derive_key_ng_ran_star); use du->assoc_id
for UE context creation instead of du->setup_req->cell[0].info.
get_ssb_arfcn(du) is unchanged and still takes the DU; other DU-based
lookups are kept where still required.
Migrate F1 DU configuration update procedures in openair2/RRC/NR/rrc_gNB_du.c
to use the cell management API instead of accessing cell data through
setup_req, completing the transition to the new multi-cell architecture.
1. update_cell_info:
- Refactored to use cell management API: takes RRC instance, old cell_id,
and new cell info; finds cell via get_cell_by_cell_id() internally.
- Returns cell container pointer (or NULL on failure) instead of void.
- When cell_id changes: removes cell from RB tree (old key), updates via
cp_f1_served_cell_info_to_cell(), re-inserts (new key); validates no
duplicate cell_id/PCI before allowing change.
- Frees old MTC when new measurement timing config is present.
- Encapsulates cell lookup and update logic.
2. rrc_gNB_process_f1_du_configuration_update:
- Uses update_cell_info() for cell modify; validates cell belongs to DU
(assoc_id) after update.
- Duplicate checking via get_cell_by_cell_id() and
rrc_get_cell_by_pci_for_du()
- For cells to add: validates duplicate cell_id globally and duplicate
PCI within DU; rejects with logging.
- MIB/SIB1 updated in cell container (cell->mib, cell->sib1); uses
du->gNB_DU_id; passes cell to label_intra_frequency_neighbours();
removes direct setup_req->cell[0] access.
Backward compatibility: setup_req remains until migration is completed;
cell-specific data is managed in the cell container and accessed via
the cell management API. Improves separation of concerns and enables
proper multi-cell support.
Refactor F1 setup processing to create and manage cell containers during DU
initialization, establishing the foundation for multi-cell architecture where
cells are managed independently from DUs.
Why: Cell information is currently tied to F1AP structures (f1ap_served_cell_info_t),
which complicates multi-cell support. Introducing cell containers at F1 setup
decouples RRC cell management from F1AP and allows cells to be managed
independently while keeping existing code paths working.
Key changes:
1. Cell container creation (cp_f1_served_cell_info_to_cell):
New helper copying F1AP served cell info into nr_rrc_cell_container_t (cell_id,
pci, plmn, tac, TDD/FDD frequency info). Extracts and stores MTC in the cell.
2. Function signature updates:
get_cell_neighbour_list() and label_intra_frequency_neighbours() now take
nr_rrc_cell_container_t* and use cell->info; improved logging (cell_id, PCI,
SSB ARFCN).
3. valid_du_in_neighbour_configs:
Removed ssb_arfcn parameter; MTC is extracted and freed inside the function.
4. F1 Setup (rrc_gNB_process_f1_setup_req):
Initialize DU cell tree (RB_INIT(&du->cells)). Populate DU-only fields
(gNB_DU_id, gNB_DU_name, rrc_ver).
Flow:
- create cell with cp_f1_served_cell_info_to_cell
- add to global tree via rrc_add_cell()
- add DU via rrc_add_du()
- attach cell to DU with rrc_add_cell_to_du().
Store MIB/SIB1/MTC in cell.
Use cell container for neighbour labeling and SIB encoding.
5. Duplicate cell detection:
Use rrc_add_cell() for global cell tree insert; collision return indicates
duplicate cell_id. Clearer error messages for Cell ID vs PCI conflicts.
Use F1AP_CauseRadioNetwork_cell_not_available for cell conflicts.
6. DU configuration update:
Use get_cell_by_cell_id() to find cell, check assoc_id, pass cell container
to label_intra_frequency_neighbours().
7. DU disconnection:
Use rrc_cleanup_du() to remove cells from global tree and free resources;
logging uses DU fields (gNB_DU_id, gNB_DU_name).
8. Global cell tree:
Initialize rrc->cells in openair_rrc_gNB_configuration().
Backward compatibility: setup_req still built via cp_f1ap_setup_request();
du->mib, du->sib1, du->mtc remain set (shared with cell container).
Add integration tests for RRC cell and DU management and UE serving-cell
logic so that multi-cell behaviour and regressions can be validated
without running the full stack.
* test_du_lookup() – DU container lookup by assoc_id:
- Multiple DU creation and insertion into RRC DU tree
- Lookup of existing DUs by assoc_id
- Non-existing and invalid assoc_ids
- Cleanup of DU containers and cells
* test_cell_lookup() – Cell management and UE association:
- Cell lookup by cell_id and PCI (global and per-DU)
- DU-specific lookup: rrc_get_cell_for_du(), rrc_get_cell_by_pci_for_du()
- Duplicate cell and PCI collision handling (including PCI reuse across
DUs and rejection of duplicate PCI within same DU)
- Cell–DU association (add/remove cells from DU containers)
- UE serving cell: add PCell/SCells, get by ID, get PCell, max serving
cells limit, single PCell enforcement
- validate_ue_cell_association(), rrc_remove_ue_scells_from_du()
- Edge cases and error handling
Add openair2/RRC/NR/tests/rrc_cell_management_test.c and extend
openair2/RRC/NR/tests/CMakeLists.txt to build and register the test.
Add functions to manage UE serving cells so the RRC can track which cells
a UE is using (PCell and SCells) for multi-cell UE context and future
SCell management.
- rrc_cell_management.c / rrc_cell_management.h:
* rrc_get_ue_serving_cell_by_id(): return serving cell by servCellIndex
(O(k) linear search, k ≤ 32).
* rrc_add_ue_serving_cell(ue, cell, serving_cell_id): add entry to UE
serving_cells with validation: reject duplicate servCellIndex with
different nci, enforce max 32 serving cells (TS 38.331), keep PCell
at index 0 for O(1) access; return existing entry if same
servCellIndex and nci.
* rrc_remove_ue_scells_from_du(ue, assoc_id): remove all serving cells
for the given DU (handover/DU disconnect); use stored assoc_id for
O(k) comparison.
* ue_get_pcell_entry(): return PCell entry (first element, O(1)).
* rrc_get_pcell_for_ue(): return PCell container from cell tree using
UE's PCell entry.
* Header: RRC_PCELL_INDEX (0), RRC_MAX_NUM_SERVING_CELLS (32), and
declarations for the above.
- UE context lifecycle:
* rrc_gNB_create_ue_context(): seq_arr_init(serving_cells).
* rrc_delete_ue_data(): seq_arr_free(serving_cells).
Move DU tree management from rrc_gNB_du.c into rrc_cell_management so that
DU and cell lookup logic live in one place, improving maintainability and
testability (there is no DU lib).
- rrc_cell_management: add du_compare(), RB_GENERATE(rrc_du_tree),
get_du_by_assoc_id(), rrc_add_du(), rrc_rm_du(), rrc_cleanup_du(),
rrc_free_du_container(); declare them in rrc_cell_management.h.
- rrc_gNB_du: move du_compare(), RB_GENERATE, get_du_by_assoc_id()
to rrc_cell_management
This commit introduces a new library module (rrc_cell_management.c/h)
to centralise functions that provides cell lookup, DU-specific cell
management, and cell lifecycle managements.
The design uses a dual-tree architecture:
- Global cell tree: RB-tree at RRC level (rrc->cells) keyed by cell_id,
used for O(log N_CELL) lookups and for maintaining num_cells.
- DU-specific storage: seq_arr_t per DU (du->cells) for iteration and
management of cells belonging to each DU.
API added:
- Global tree: get_cell_by_cell_id()(finds cell using global RB-tree
lookup (O(log N_CELL) complexity); rrc_add_cell(); rrc_rm_cell()
(rrc_rm_cell removes from tree, decrements num_cells, and frees the
cell via rrc_free_cell_container).
- DU-local seq_arr: rrc_get_cell_for_du(), rrc_get_cell_by_pci_for_du(),
rrc_add_cell_to_du() (with duplicate cell_id/PCI checks).
- Cleanup: rrc_free_cell_container() (frees ASN.1 MIB/SIB1/MTC and
container
Build: add rrc_cell_management static library in openair2/RRC/NR;
link it into nr_rrc from top-level CMakeLists.txt.
Add foundational data structures in nr_rrc_defs.h for multi-cell handling
in RRC, separating DU management from cell management.
Design uses a global cell tree for O(log N) lookups while keeping cell
ownership in DUs for locality and maintenance.
The implementation maintains backward compatibility and follows the same
patterns as existing DU and CUUP management in the codebase, i.e. RB-trees
with logarithmic complexity for scalable multi-cell deployments.
- Cell container structures:
* nr_rrc_cell_container_t: cell-specific data (cell_id, pci, plmn, tac,
frequency info, mib, sib1, mtc)
* nr_rrc_cell_info_t: TDD/FDD modes; frequency structs nr_rrc_freq_info_t,
nr_rrc_tdd_info_t, nr_rrc_fdd_info_t
- UE serving cell tracking:
* ue_serving_cell_t: nci, serving_cell_id (ServCellIndex TS 38.331,
0=PCell, 1-31=SCell), assoc_id for fast DU lookup
* gNB_RRC_UE_t: seq_arr_t serving_cells, with PCell always being the
first in the sequence
- DU container refactoring:
* nr_rrc_du_container_t: DU-only fields (gNB_DU_id, gNB_DU_name, rrc_ver);
seq_arr_t cells for per-DU iteration; setup_req/mib/sib1/mtc kept for
backward compatibility
- Global cell tree:
* gNB_RRC_INST_s: RB_HEAD(rrc_cell_tree, nr_rrc_cell_container_t) cells,
num_cells (data only; lookup helpers get_cell_by_cell_id/get_cell_by_pci
to be added separately)
Replace generic UE event log with explicit INFO log including UE ID and RNTI
when removing a UE context and centralize access to UE fields via a local
pointer.
rrc_delete_ue_data removes the all the list in the UE context, including the
serving cells, and therefore the cell id should not be logged in the function
responsible for the removal of the UE context, which at this point is already
emptied and while the cells themselves are still there (in the DU/global cell
structures), the lists in the UE context are empty.
* Commit applies to Setup Request, CU/DU Configuration Update
* Set standard compliant max number of cells per DU
* Allocate large lists on the heap to prevent stack overflow
due to the large size
* Update relevant free functions
* Also, fix bug in eq_f1ap_cu_configuration_update
Also, improve comments in struct definition.
Implement TS 38.473 transparency for CellGroupConfig forwarding and handle re-establishment on a different DU
This MR implements the following fixes that are relevant in RRC
procedures (e.g. re-establishment, reconfiguration):
1. Transparent CellGroupConfig forwarding
This MR implements TS 38.473 transparency requirements by ensuring that
the CellGroupConfig IE is transparently forwarded from the gNB-DU to the
UE without any re-encoding at the gNB-CU. The CU stores and forwards the
encoded bytes transparently, while the DU is responsible for all
encoding and modifications (e.g., reestablishRLC flags). Motivation
Motivation: The 3GPP TS 38.473 specification mandates that the
CellGroupConfig IE shall be transparently signaled to the UE.
Previously, the CU was re-encoding CellGroupConfig depending on the
scenario, instead of retrieving it from the DU, violating the
transparency requirement. CU may decode for internal use but must not
re-encode for forwarding. Solution
Solution: Core Principle: The CU stores the encoded CellGroupConfig
bytes received from the DU and forwards them directly to the UE without
any re-encoding. The DU handles all encoding and modifications.
Key Changes:
1. Transparent Forwarding in RRC Reconfiguration
- Modified build_RRCReconfiguration_IEs() to use pre-encoded bytes
directly
- Changed parameter from cell_group_config to cgc (encoded byte
array with buffer and size)
2. Encoded Bytes Storage
- Added byte_array_t mcg field to RRC UE structure to store encoded
CellGroupConfig
- Added store_cgc() helper function to save encoded cell group in
the RRC UE Context at gNB (from F1AP messages)
3. DU Encoding Responsibilities
- Add gNB-DU Configuration Query IE support to trigger cgc encoding
to request CellGroupConfig from DU
- DU encodes CellGroupConfig with proper reestablishRLC flags
during re-establishment
- DU removes SRB1 from rlc-BearerToAddModList during
re-establishment (SRB1 re-establishment is done before
RRCReconfiguration)
4. New functions
- Add rrc_detect_reestablishment() function to detect
re-establishment during UE Context Modification
- Extracted rrc_gNB_first_reconfiguration_after_reestablishment()
function to handle first reconfiguration after re-establishment
- Added dump_cgc() and dump_mcg() utility functions for debugging
purposes
5. Re-establishment Flow
- rrc_gNB_process_RRCReestablishmentComplete() requests
CellGroupConfig from DU via gNB_DU_Configuration_Query in UE
Context Modification Request
- DU detects re-establishment and add reestablishRLC IEs
- CU stores encoded CGC from the UE Context Modification Response
and forwards it transparently in subsequent RRC Reconfiguration
Testing
Manual Testing:
- RRC re-establishment procedure completes successfully
- RRC Reconfiguration after re-establishment includes all DU-provided information
Issues fixed
Closes issue #837
2. Trigger UE Context Setup fallback upon reestablishment on DU
different from the original one
As per 38.401 §8.7: if the UE accesses a DU different from the original
one during re-establishment, the CU must trigger UE Context Setup toward
the new DU. This refers to steps 9-10 and steps 9’-10’. Either one or
the other can be executed during re-establishment.
e.g. if this happens during handover, it shall trigger a UE Context
Setup fallback on the CU.
This MR implements the required behavior by:
- Adding a new helper function rrc_handle_f1_ho_reestab_on_target() to
handle F1 handover reestablishment on target DU. The function triggers
UE Context Setup procedure when the UE reestablishes on the target DU
during an ongoing F1 handover.
- Calling this function when detecting that the UE is reestablishing on
the target DU during handover, i.e.: (1) from
handle_rrcReestablishmentComplete(), as per 38.401 §8.7, NOTE on steps
9-10: CU gets UL RRC MESSAGE TRANSFER from a DU different than the
original (2) from rrc_CU_process_ue_modification_required, as per
38.401 §8.7, NOTE on steps 9'-10': CU gets a UE CONTEXT MODIFICATION
REQUIRED from a DU different from the original one.
Also:
- add helper rrc_fill_f1_ue_context_setup and adopt it in handover
- move DRB list filler fill_drb_to_be_setup into rrc_gNB.c and rename it
rrc_fill_f1_drb_to_setup for consistency
See also TS 38.401 Figure 8.7-1 "RRC connection reestablishment
procedure" for reference
3. DU: Handle missing old UE context in DL RRC Message Transfer
During F1 handover reestablishment, the CU may forward a DL RRC Message
Transfer to the target DU with old_gNB_DU_ue_id included, even though
the target DU does not have the old UE context yet.
The code previously used AssertFatal when the old UE context was not
found, causing a crash: "CU claims we should know UE %04x, but we don't"
According to TS 38.473, the gNB-DU shall release the old gNB-DU UE F1AP ID only:
> if the gNB-DU identifies the UE-associated logical F1-connection If
> there is no matching connection, there is nothing to release.
Fix:
- Check if old UE context exists before accessing it
- If old UE does not exist, log error, clean up any stale F1 UE data,
and return early (do not deliver RRC message since reestablishment
can't be completed)
The goal is to address a recurrent issue in the F1 pipeline, see
jenkins-oai.eurecom.fr/job/RAN-SA-Handover-CN5G/514:
Assertion (oldUE) failed!
In dl_rrc_message_transfer() /oai-ran/openair2/LAYER2/NR_MAC_gNB/mac_rrc_dl_handler.c:956
CU claims we should know UE 35ce, but we don't
This commit fixes the timing of SRB and DRB PDCP re-establishment
during RRC connection re-establishment to align with 3GPP TS 38.331
specifications.
Key Changes:
1. SRB1 activation and re-establishment (TS 38.331 5.3.7.4):
- Move SRB1 activation to rrc_gNB_generate_RRCReestablishment()
- Use SRB1 constant instead of magic number 1 for clarity
- Remove redundant security configuration loop (handled by
nr_pdcp_reestablishment internally)
2. SRB2 re-establishment (TS 38.331 5.3.5.6.3 SRB addition/modification):
- Move SRB2 PDCP re-establishment from rrc_gNB_process_RRCReestablishmentComplete()
to rrc_gNB_generate_dedicatedRRCReconfiguration(): per spec: SRB2
should be re-established in the first RRCReconfiguration after
re-establishment (with reestablishPDCP=true flag)
3. DRB re-establishment (TS 38.331 5.3.5.6.5 DRB addition/modification):
- Move cuup_notify_reestablishment() from rrc_gNB_process_RRCReestablishmentComplete()
to rrc_gNB_generate_dedicatedRRCReconfiguration(). e.g at the first
reconfiguration after reestablishment
- Ensures CU-UP is notified at the correct time
As per TS 38.401 §8.7: if the UE accesses a DU different from the original
one during re-establishment, the CU must trigger UE Context Setup toward
the new DU. This refers to steps 9-10 and steps 9'-10'. Either one or the
other can be executed during re-establishment.
e.g. if this happens during F1 handover, it shall trigger a
UE Context Setup fallback on the CU.
This commit implements the required behavior:
1. Detection mechanism:
- Add `old_du_assoc_id` field to `f1_ue_data_t` to store the original
DU association ID
- At RRCReestablishmentRequest: Store original `du_assoc_id` in
`old_du_assoc_id` and update `du_assoc_id` to the new DU
- At RRCReestablishmentComplete: Compare `old_du_assoc_id` with the
`assoc_id` from the Complete message to detect different DU
2. UE Context Setup trigger:
- In `rrc_gNB_process_RRCReestablishmentComplete()`: When different DU
is detected, call `rrc_f1_ue_context_setup_for_target_du()` to trigger
UE Context Setup procedure (per TS 38.401 §8.7, NOTE on steps 9-10)
upon reception of UL RRC MESSAGE TRANSFER
- In `rrc_CU_process_ue_modification_required()`: Refuse UE Context
Modification Required when `old_du_assoc_id != 0` to avoid conflicts
with the ongoing UE Context Setup procedure (per TS 38.401 §8.7, NOTE
on steps 9'-10')
3. UE Context Setup:
- Replace `clone_CellGroupConfig()` with `get_cellgroup_config()` in
UE Context Setup handler
- Call `update_cellgroup_for_reestablishment()` during UE Context Setup
when `reestablish_rlc` flag is set to prepare CellGroupConfig with
reestablishRLC flags
- Clean up `old_du_assoc_id` in `rrc_CU_process_ue_context_setup_response()`
- Add `free_ue_context_mod_req()` call after UE Context Modification request
4. Function signature updates:
- Update `handle_rrcReestablishmentComplete()` to accept `gNB_DU_ue_id`
and `assoc_id` parameters, change return type from `int` to `void`
- Update `rrc_gNB_process_RRCReestablishmentComplete()` to accept
`assoc_id` parameter
- Update `rrc_gNB_decode_dcch()` to accept and forward `assoc_id` parameter
Re-establishment on different DU flow (TS 38.401 §8.7, steps 9-10):
1. UE sends RRCReestablishmentRequest to new DU
2. DU forwards to CU via UL RRC MESSAGE TRANSFER
3. CU detects different DU (`assoc_id != ue_data.du_assoc_id`):
- Stores `old_du_assoc_id = ue_data.du_assoc_id` (original DU)
- Updates `ue_data.du_assoc_id = assoc_id` (new DU)
4. CU sends RRCReestablishment to UE
5. UE sends RRCReestablishmentComplete to new DU
6. DU forwards to CU via UL RRC MESSAGE TRANSFER
7. CU detects different DU scenario (with old_du_assoc_id):
- Triggers UE Context Setup Request to new DU via `rrc_f1_ue_context_setup_for_target_du()`
8. DU receives UE Context Setup Request:
- Detects re-establishment (`UE->reestablish_rlc` flag)
- Calls `update_cellgroup_for_reestablishment()` to set reestablishRLC flags
- Encodes CellGroupConfig with reestablishRLC flags and sends to CU
9. CU receives UE Context Setup Response:
- Stores encoded CellGroupConfig
- Clears `old_du_assoc_id = 0`
10. CU sends RRC Reconfiguration with transparent CellGroupConfig to UE
This commit implements transparent forwarding of CellGroupConfig
as required by TS 38.473, eliminating CU-side decode/re-encode
cycles that violate transparency requirements.
Main Design Change:
- Before: CU decoded CellGroupConfig from DU, stored in the UE
context then re-encoded when sending to UE. CU constructed
new CellGroupConfig after RRCReestablishmentComplete.
- After: CU requests CellGroupConfig from DU via UE Context Modification
Request with `gNB_DU_Configuration_Query=true`, DU sends CellGroupConfig
which CU stores as encoded `byte_array_t` and forwards transparently
via reconfiguration without decode/re-encode cycles
To this purpose, all decode operations of CellGroupConfig were removed
from DU and all encode operations were removed from the CU.
Key Changes:
CU:
- Replace NR_CellGroupConfig_t* masterCellGroup with byte_array_t mcg in
gNB_RRC_UE_t for storing encoded CellGroupConfig
- Rename cell_group_config to cgc in nr_rrc_reconfig_param_t for brevity
- Implement transparent forwarding in build_RRCReconfiguration_IEs()
- Add helper functions:
- `store_cgc()` to store encoded bytes
- `get_meas_gap_config()`: Decode MeasGapConfig from DU to CU response
- `rrc_detect_reestablishment()` to detect re-establishment by decoding
temporarily (only for detection)
- Remove legacy decode/re-encode paths in RRC message generation
- Update all CellGroupConfig storage to use encoded bytes
- Update reconfiguration generation to accept is_reestablishment parameter
DU:
- Add `get_cellgroup_config()` to select source (CellGroup vs reconfigCellGroup)
based on re-establishment state
- Add re-establishment detection logic in `ue_context_modification_request()`
- Add `update_cellgroup_for_reestablishment()` to set reestablishRLC flags and
remove SRB1 from bearer list
- When `gNB_DU_Configuration_Query` is present and re-establishment detected:
- Clones from reconfigCellGroup (which contains spCellConfig) instead of
CellGroup (where spCellConfig was removed)
- Sets `reestablishRLC` flags for all bearers except SRB1
- Removes SRB1 from bearer list (already re-established)
Data Structure Changes:
- gNB_RRC_UE_t: Add byte_array_t mcg field
- nr_rrc_reconfig_param_t: Change cell_group_config to cgc (byte_array_t*)
- Remove masterCellGroup field usage in favor of encoded mcg
New re-establishment flow:
1. UE sends RRCReestablishmentRequest
2. CU processes -> sends RRCReestablishment
3. CU sends RRCReestablishmentComplete
4. CU sends UE Context Modification Request to DU with `gNB_DU_Configuration_Query=true`
5. DU detects re-establishment (`UE->reestablish_rlc && UE->reconfigCellGroup != NULL`):
- Clones `UE->reconfigCellGroup` -> `new_CellGroup` (contains spCellConfig)
- Sets `reestablishRLC` flags for all bearers except SRB1
- Removes SRB1 from bearer list (already re-established)
- Encodes `new_CellGroup` and sends to CU
6. CU receives encoded CellGroupConfig -> stores in `UE->mcg` via `store_cgc()`
7. CU detects re-establishment via `rrc_detect_reestablishment()`
8. CU calls `rrc_gNB_generate_dedicatedRRCReconfiguration()` with `is_reestablishment=true`:
- Creates SRB/DRB lists with re-establishment flags
- Generates RRC Reconfiguration with transparent CellGroupConfig
- Sends to UE
Why spCellConfig must be added in the DU in case of re-establishment:
With transparent forwarding, CU requests CellGroupConfig from DU instead
of constructing it. During re-establishment, DU's runtime CellGroup has
spCellConfig = NULL (removed per TS 38.331 §5.3.7.2). However, for the
gNB_DU_Configuration_Query response, DU must provide a complete CellGroupConfig
including spCellConfig. Therefore, DU restores spCellConfig by encoding
reconfigCellGroup (with the original spCellConfig) in CellGroupConfig.
In the old design CU constructed CellGroupConfig itself in
`rrc_gNB_process_RRCReestablishmentComplete()` and used `spCellConfig`
from its stored `masterCellGroup`.
Closes#837
Apply CGC encoding through GNB-DU Configuration Query. This applies to the
pdu session release path (rrc_gNB_send_f1_drb_release_request) and E1 bearer
mod / DRB add+release path (rrc_gNB_generate_UeContextModificationRequest).
This is necessary to implement 3GPP TS 38.473 requirement for
gNB-DU Configuration Query IE in UE Context Modification Request:
"If the GNB-DU Configuration Query IE is contained in the UE CONTEXT
MODIFICATION REQUEST message, gNB-DU shall include the CellGroupConfig
IE in the DU To CU RRC Information IE in the UE CONTEXT MODIFICATION
RESPONSE message."
i.e.: The DU sends the CGC only when this IE is enabled in the REQ
message from the CU. The only other scenario according to the same
specs is when the Full Configuration IE is present. Outside of these
two cases, CGC shall not be sent.
Add debugging utilities dump_cgc() and dump_mcg() to decode and
print CellGroupConfig in XER format when DEBUG_ASN1 flag is enabled.
This helps debug RRC Reconfiguration messages containing masterCellGroup.
Add intermediate fallback to rrc_gNB_get_ue_context_by_rnti_any_du() in
re-establishment request handling to better handle cases where UE
re-establishes on a different DU.
RNTI is NOT globally unique - different DUs can assign the same RNTI to
different UEs. The assoc_id check in rrc_gNB_get_ue_context_by_rnti()
disambiguates RNTI across DUs and prevents returning the wrong UE.
However, during re-establishment on a different DU, du_assoc_id hasn't
been updated yet (message comes from new DU, but ue_data.du_assoc_id
still points to old DU), causing the primary lookup to fail even though
the UE exists.
The lookup now uses a three-tier fallback:
1. Primary: rrc_gNB_get_ue_context_by_rnti() with assoc_id check
(normal case: same DU)
2. Fallback 1: rrc_gNB_get_ue_context_by_rnti_any_du() by RNTI only
(re-establishment on different DU)
3. Fallback 2: rrc_gNB_get_ue_context_source_cell() using physCellId
(handover scenarios)
- Remove unused masterCellGroup_from_DU parameter from rrc_gNB_generate_RRCReestablishment() as it is not used in the RRC
re-establishment generation, RRCReestablishment message does not contain CellGroupConfig which is obtained later via UE Context Modification Request/Response
- Update function documentation
- Initialize security_parameters struct to zero for safety
- Add check on ciphering and integrity algorithm ranges
When a UE re-establishes on a different DU, the physCellId in the
re-establishment request (from the old cell) will differ from the
new DU's physCellId. The previous check incorrectly treated this as
a "too fast movement" scenario and triggered fallback to RRC setup.
This fix distinguishes between two scenarios:
1. Different DU scenario: physCellId differs because UE is on a
different DU - this is legitimate and should be allowed. UE
Context Setup will be triggered at RRCReestablishmentComplete.
2. Same DU but different physCellId: "too fast movement" scenario
- fallback to RRC setup as before.
The fix checks if assoc_id != ue_data.du_assoc_id to detect a
different DU scenario and allows re-establishment in that case.
This addresses the issue where re-establishment on a different DU
was incorrectly rejected, preventing proper UE Context Setup per
TS 38.401 Section 8.7.
Handle target DU UE context setup when handover preparation info
is unavailable (i.e. re-establishment scenario) by retrieving
secondary UE ID from F1 UE data.
rrc_f1_ue_context_setup_for_target_du is either applying to
handover or re-establishment. In the latter scenario, populate
DU UE ID, which should be known.
semi-manual remove of not used #define commands
As i was upset to see all these #define with no code under, i made a
global pass to remove the obvious cases semi-manual remove of not used
bodies
manual script, then a lot of manual review
grep -IRs "#define" ../openair* ../common/* ../executables/ ../nfapi/ ../radio/ | \
fgrep -v '(' | fgrep -v '//' |awk '{print $2}' | egrep -v "#define *$n"| \
while read n ; do
grep -IRs $n ../openair* ../common/* ../executables/ ../nfapi/ ../radio/ | grep -v "#define *$n" | grep -q $n || echo $n;
done
will give a decent list of #define never used. Then, I think we should
keep lists of # define when it comes from standards, even if the code
doesn't use it right now
Add Ethernet PDU session support and make PDU session request configurable
This MR adds support for Ethernet PDU sessions, and makes PDU sessions
configurable: per-PDU session ID, type (IPv4/IPv4v6/IPv6/Ethernet [1]),
DNN, NSSAI.
Concretely, it adds a new configuration file section pdu_sessions below
uicc0 that looks like this if everything is specified (default values
are shown):
uicc0:
[...]
pdu_sessions:
- id: 1
type: "IPv4"
nssai_sst: 1
nssai_sd: 0xffffff
dnn: "oai"
It is possible to list multiple PDU sessions (add new line - id: 2 to
request a second PDU session). It is backwards-compatible to the current
PDU session configuration (uicc0.dnn/nssai_sst/etc), the idea being that
either legacy or new configuration could be used, but (1) if
pdu_sessions exist, it will overwrite the legacy configuration, and (2)
multiple PDU sessions, and type, can only be configured using the new
config. The old parameters --extra-pdu-id and --default-pdu-id are not
accepted anymore. Documentation has been added to the UE tutorial.
It is possible to test an Ethernet PDU session [1]. It is possible to
test the PDU session inside the UE by verifying it has an TAP interface
oaitap_ue1, and ARPing the data network (arping has been added to
oai-nr-ue container for that purpose):
ip addr add 192.168.72.140/26 dev oaitap_ue1 # same subnet as data network!
ip link set dev oaitap_ue1 up
arping -c 20 -I oaitap_ue1 192.168.72.135 # will send ARP request in Ethernet frame to get IP address of data network
[1] See description MR !3769 for more information. On the UE side, only
the type has to be changed to "Ethernet".
NGAP: improve error handling in RRCReconfiguration from Handover Command decoding
This MR refactors doRRCReconfiguration_from_HandoverCommand for consistency and
safety, and enables NGAP Handover Cancel encoding/decoding.
- Refactored doRRCReconfiguration_from_HandoverCommand function:
- Changed signature to return byte_array_t instead of taking a buffer parameter
- Prevents buffer overflow by auto-sizing memory with uper_encode_to_new_buffer
- Input validation
- HandoverCommand structure validation
- Error handling and cleanup for encode/decode failures
- ASN.1 structure cleanup on all error paths
- Updated caller in rrc_gNB_NGAP.c: use new byte_array_t return signature,
added buffer cleanup with free_byte_array(), sends Handover Cancel to AMF on
decoding failure (source gNB)
- Improved error logging
- NGAP Handover Cancel encoding/decoding support
- Added missing Handover Cancel ack case handler for
NGAP_ProcedureCode_id_HandoverCancel in ngap_gNB_decode_initiating_message()
to decode and log incoming Handover Cancel Ack message
- Added NGAP_ProcedureCode_id_HandoverCancel to the list of supported
initiating message procedure codes in ngap_gNB_encode_initiating() allowing
the gNB to encode and send Handover Cancel messages
Note: The Handover Cancel procedure is already implemented elsewhere in the NGAP
stack; these changes complete support by ensuring the procedure code is
recognized in both encoder and decoder.
Closes#1043
- Add function documentation blocks for `rrc_fill_f1_ue_context_setup`,
`rrc_f1_ue_context_setup_for_target_du`, and `rrc_f1_ue_context_setup_from_e1_response`
explaining their purpose, parameters, and usage scenarios
- Add inline comments throughout these functions
Improve maintainability by centralizing common F1AP UE context setup
logic into reusable helper functions, enabling consistent handling
and clear serving/target DU entry points for different scenarios.
Code duplication prevention is a beneficial side effect, since at
least one helper function is adopted in subsequent commits.
Major changes:
- Move DRB list filler from external file into rrc_gNB.c and rename
fill_drb_to_be_setup to rrc_fill_f1_drb_to_setup for naming
consistency
- Add static helper rrc_fill_f1_ue_context_setup to populate common
fields shared between serving DU and target DU scenarios:
- Rename rrc_gNB_generate_UeContextSetupRequest to
rrc_f1_ue_context_setup_from_e1_response to clarify it prepares
F1AP context setup from E1AP bearer setup response for serving DU
- Add rrc_f1_ue_context_setup_for_target_du (for target DU in
handover/reestablishment scenarios)
- Adopt helper rrc_fill_f1_ue_context_setup in both functions
Defacto, the PDU session ID for noS1 modes is already hardcoded, as
starting the nr-softmodem with --noS1 --default-pdu-id 1 leads to
Assertion (entity != ((void *)0)) failed!
In start_sdap_tun_gnb_first_ue_default_pdu_session() openair2/SDAP/nr_sdap/nr_sdap.c:163
Further, the --default-pdu-id parameter will be deactivated in a later
commit, and we cannot rely on it. Therefore:
- hardcode noS1 PDU ID (also used in --do-ra/--phy-test modes) to 10 and
use in gNB&UE
- pass the PDU session ID used in SDAP entity initialization down to
start_sdap_tun_gnb_first_ue_default_pdu_session() to always use the
correct one
NR UE: add neighboring cell measurements and measurement report of event A3
This is a rework of MR !2385 (closed), the goal is to add neighboring cell
measurements and measurement report of event A3 for NR UE.
This MR was tested with:
- 3rd-party gNB
- 2 OAI-gNB-DUs
The neighboring cell measurements and measurement report of event A3 for OAI-UE
are working as expected.
While testing the gNB with two hypotetical neighbors, some issues were found
with A3 event configuration.
The configuration of neighbors is:
neighbour_list = (
{
nr_cellid = 12345679L;
neighbour_cell_configuration = (
{
gNB_ID = 0xba0;
nr_cellid = 720898;
physical_cellId = 1;
absoluteFrequencySSB= 621312;
subcarrierSpacing = 1;
band = 78;
plmn = { mcc = 505; mnc = 01; mnc_length = 2 };
tracking_area_code = 1;
},
{
gNB_ID = 0xea0;
nr_cellid = 1345678L;
physical_cellId = 2;
absoluteFrequencySSB= 640000;
subcarrierSpacing = 1;
band = 78;
plmn = { mcc = 505; mnc = 01; mnc_length = 2 };
tracking_area_code = 1;
}
);
}
);
There were two problems.
The first problem is:
- when only default A3 event is configured, it is duplicated in the
RRC Reconfiguration Report Config To AddMod list with IDs 4 and 5
To test this case, the event configuration is:
nr_measurement_configuration = {
Periodical = {
enable = 1;
includeBeamMeasurements = 1;
maxNrofRS_IndexesToReport = 4;
};
A2 = {
enable = 1;
threshold = 60;
time_to_trigger = 1;
};
A3 = (
{
physCellId = -1;
offset = 15;
hysteresis = 2;
time_to_trigger = 3
}
);
};
The second problem is:
- when configuring an A3 event with an unknown physCellId, the gNB
does not include any A3 event in the RRC Reconfiguration Report
Config To AddMod list (which is correct), but configures some
meas ID with nonexistant Report Config IDs
To test this case, the event configuration is:
nr_measurement_configuration = {
Periodical = {
enable = 1;
includeBeamMeasurements = 1;
maxNrofRS_IndexesToReport = 4;
};
A2 = {
enable = 1;
threshold = 60;
time_to_trigger = 1;
};
A3 = (
{
physCellId = 10;
offset = 15;
hysteresis = 2;
time_to_trigger = 3
}
);
};
Reworking A3 event configuration as done in this commit solves both
issues.
- Refactor function to return byte_array_t instead of taking buffer
parameter for consistency with other encoding functions
(do_RRCReconfiguration, do_HO_RRCReconfiguration) and to prevent buffer
overflow issues since the memory size is determined automatically
- Add comprehensive error checking:
* Input validation
* Check return of each decode (HandoverCommand
and RRCReconfiguration)
* Validate HandoverCommand structure before access
* Validate OCTET_STRING before decoding RRCReconfiguration
* Error handling and cleanup for enc/dec failures
- Update caller in rrc_gNB_NGAP.c
* use new signature
* free buffer
* send HO Cancel on decoding failure (source gNB)
Closes#1043
Fix bug "no AMF for UE"
It might happen that the RRC does not know the AMF UE NGAP ID, yet. Even
in that case, we should forward the release request to the NGAP module,
which can either forward a message to the AMF, or reply back to release
the UE. This avoids an error where the CU claims there was no AMF, when
there actually is.
One possible problematic behavior is if a UE disconnects before the gNB
receives an NGAP Initial Context Setup. In this case, the AMF UE NGAP ID
was not forwarded to the RRC (although it was known at NGAP), thus
blocking the release of the UE.
This is the main fix, the rest are minor fixes:
- store AMF UE NGAP ID as early as possible
- warn in MAC if UE unknown for UE context release command
- show TEIDs with correct endianness in GTP
- avoid NG Setup Failure+Setup log.
In the Initial Context Setup message, the NGAP forwards the AMF UE ID,
but not in the DL NAS Message, although 38.413 says, in $8.3.1.2 either
> The NG-RAN node shall use the AMF UE NGAP ID IE and RAN UE NGAP ID IE
> received in the INITIAL CONTEXT SETUP REQUEST message as identification
> of the logical connection
or in $8.6.2.2
> The NG-RAN node shall use the AMF UE NGAP ID IE and RAN UE NGAP ID IE
> received in the DOWNLINK NAS TRANSPORT message as identification of the
> logical connection
So forward in both cases for harmonization.
It might happen that the RRC does not know the AMF UE NGAP ID, yet. Even
in that case, we should forward the release request to the NGAP module,
which can either forward a message to the AMF, or reply back to release
the UE.
Reported-By: Jegor Zelenjak <jzelenjak@proton.me>
NR NGAP (N2HO) : Fix Time UE Stayed in Cell IE type and calculation
According to 3GPP TS 38.413, the 'Time UE Stayed in Cell' IE is an
integer ranging from 0 to 4095. This patch updates the data structure
to reflect the correct bit width and implements the dynamic calculation
based on the UE's residence time.
- Change time_in_cell from long to uint16_t in ngap_messages_types.h.
- Replace dummy value with real-time calculation in rrc_gNB_NGAP.c.
- Implement a ceiling of 4095 to comply with the 12-bit protocol limit.
Ref: 3GPP TS 38.413 Section 9.3.1.97
Refactor key derivation logic to properly handle Next Hop (NH) chain
synchronization according to 3GPP TS 33.501 specifications for both RRC
Reestablishment and Master Key Update procedures.
Changes in rrc_gNB.c:
- Clarify key derivation in rrc_gNB_generate_RRCReestablishment by explicitly
selecting base key (NH or KgNB) based on nh_ncc value
- Add comment explaining vertical vs horizontal derivation logic
Changes in rrc_UE.c:
Refactored the NH chain synchronization and key derivation code to match
TS 33.501 terminology:
- nr_sync_nh_chain(): Common helper to synchronize NH parameter chain per
TS 33.501 Annex A.10, supporting both Master Key Update and RRC Reestablishment
procedures
- nr_derive_kgnb_horizontal(): Derive KNG-RAN* from current KgNB when NCC values
match (horizontal derivation per TS 33.501 A.11/A.12)
- nr_derive_kgnb_vertical(): Derive KNG-RAN* from synchronized NH after NH chain
sync (vertical derivation per TS 33.501 A.11/A.12)
- nr_update_kgnb_from_ncc(): Unified function implementing TS 33.501 6.9.2.3.4
logic for updating KgNB based on received nextHopChainingCount
- Refactor as_security_key_update(): Use new nr_update_kgnb_from_ncc() helper
function for cleaner, more maintainable code
- Fix nr_rrc_ue_process_rrcReestablishment(): Properly handle received
nextHopChainingCount and update KgNB using unified helper function
- Replaced the previous nr_rrc_nh_update() helper with these functions to
improve clarity and alignment with the specification.
- Add debug logging for key derivation process
Key NAS deriver utils:
- update derive_kgnb documentation and protect input keys with const attribute
Closes#857
According to 3GPP TS 38.413, the 'Time UE Stayed in Cell' IE is an
integer ranging from 0 to 4095. This patch updates the data structure
to reflect the correct bit width and implements the dynamic calculation
based on the UE's residence time.
- Change time_in_cell from long to uint16_t in ngap_messages_types.h.
- Replace dummy value with real-time calculation in rrc_gNB_NGAP.c.
- Implement a ceiling of 4095 to comply with the 12-bit protocol limit.
Ref: 3GPP TS 38.413 Section 9.3.1.97
Per TS 33.501 6.9.2.3.4 and Fig 6.9.2.1.1-1, when sending
RRCReestablishment with nextHopChainingCount, the gNB is staying at
the same NCC level (not advancing). Therefore, horizontal derivation
from the currently active KgNB must be used, not vertical derivation
from NH.
Vertical derivation (from NH) is only used when advancing to a new
NCC level, which happens during handover or masterKeyUpdate procedures.
The previous implementation incorrectly used vertical derivation from
NH whenever nh_ncc > 0, which caused key mismatch between gNB and UE
during reestablishment after handover, leading to integrity check
failures.
This fix ensures both gNB and UE use horizontal derivation when
nextHopChainingCount matches the current NCC level, aligning with the
specification's "virtual NH at NCC=0" model where:
- Horizontal derivation = derive KNG-RAN* from currently active KgNB
- Vertical derivation = derive KNG-RAN* from NH (only when advancing NCC)
These logs are very helpful to identify cell configuration
changes in MAC/PHY, for monitoring purposes, and to rapidly
signal integrity failures during re-establishment.
The RNTI from the target context was not updated after HO acknowledge
this led to a failure in the first re-establishment after HO.
This commit is introducing the function nr_rrc_apply_target_context
in nr_rrc_n2_ho_acknowledge() and also updates the cell ID for
consistency.
Refactor handover target context application logic into a reusable
function nr_rrc_apply_target_context() that updates both F1AP
associations (secondary UE and DU association) and RNTI from the
target handover context.
And apply to rrc_CU_process_ue_context_modification_response()
Per TS 33.501 6.9.2.3.4 and Fig 6.9.2.1.1-1, when sending
RRCReestablishment with nextHopChainingCount, the gNB is staying at
the same NCC level (not advancing). Therefore, horizontal derivation
from the currently active KgNB must be used, not vertical derivation
from NH.
Vertical derivation (from NH) is only used when advancing to a new
NCC level, which happens during handover or masterKeyUpdate procedures.
The previous implementation incorrectly used vertical derivation from
NH whenever nh_ncc > 0, which caused key mismatch between gNB and UE
during reestablishment after handover, leading to integrity check
failures.
This fix ensures both gNB and UE use horizontal derivation when
nextHopChainingCount matches the current NCC level, aligning with the
specification's "virtual NH at NCC=0" model where:
- Horizontal derivation = derive KNG-RAN* from currently active KgNB
- Vertical derivation = derive KNG-RAN* from NH (only when advancing NCC)
Refactor key derivation logic to properly handle Next Hop (NH) chain
synchronization according to 3GPP TS 33.501 specifications for both
RRC Reestablishment and Master Key Update procedures.
Changes in rrc_gNB.c:
- Clarify key derivation in rrc_gNB_generate_RRCReestablishment by
explicitly selecting base key (NH or KgNB) based on nh_ncc value
- Add comment explaining vertical vs horizontal derivation logic
Changes in rrc_UE.c:
- Add nr_sync_nh_chain(): Common helper to synchronize NH parameter
chain per TS 33.501 Annex A.10, supporting both Master Key Update
and RRC Reestablishment procedures
- Add nr_derive_kgnb_horizontal(): Derive KNG-RAN* from current KgNB
when NCC values match (horizontal derivation per TS 33.501 A.11/A.12)
- Add nr_derive_kgnb_vertical(): Derive KNG-RAN* from synchronized NH
after NH chain sync (vertical derivation per TS 33.501 A.11/A.12)
- Add nr_update_kgnb_from_ncc(): Unified function implementing TS 33.501
6.9.2.3.4 logic for updating KgNB based on received nextHopChainingCount
- Refactor as_security_key_update(): Use new nr_update_kgnb_from_ncc()
helper function for cleaner, more maintainable code
- Fix nr_rrc_ue_process_rrcReestablishment(): Properly handle received
nextHopChainingCount and update KgNB using unified helper function
- Add debug logging for key derivation process
Key NAS deriver utils:
- update derive_kgnb documentation and protect input keys with const attribute
Guido Casati