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.
However, the primary purpose of DL RRC MESSAGE TRANSFER is to deliver
the RRC message to the UE. The RRC message delivery is independent of
whether the old UE context can be retrieved. Per TS 38.473, the RRC
message must be delivered to the new UE regardless of old context
retrieval status.
Additionally, per TS 38.331 5.3.7.2 and 5.3.7.4, during reestablishment:
- The UE releases spCellConfig, which must be removed from CellGroupConfig
- SRB1 RLC must be reconfigured with specific parameters
These operations are required for the new UE during reestablishment and
are independent of whether the old UE context can be retrieved.
Fixes:
- Check if old UE context exists before accessing it
- If old UE does not exist, log error and clean up any stale F1 UE data,
but continue to deliver the RRC message
- Restructure code so context transfer only happens when oldUE exists
- Keep GTP-U update and RLC context transfer inside oldUE check (they
require old UE context to exist)
- Move spCellConfig handling and reestablish_rlc flag to execute
regardless during re-establishemnt (per TS 38.331 5.3.7.2)
- Move SRB1 RLC reconfiguration outside the oldUE check so it executes
regardless during re-establishment (per TS 38.331 5.3.7.4)
- Add function documentation and improve spec references in comments
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.
This field will be adopted to trigger cgc encoding at DU,
according to the specs (see subsequent commit for details).
Changes:
- Add gNB_DU_Configuration_Query field to f1ap_ue_context_mod_req_t
- Implement encoding/decoding
- Add to cp, eq, and free functions for the new field
- Update tests to include the new field
Issue: sometimes it happens that an ul failure occurs in the handover
pipeline, UE reconnects with different UE ID and fetch_du_by_ue_id fails.
- Modified fetch_du_by_ue_id in telnetsrv_ci.c to automatically find
the connected UE when no UE ID is provided, similar to other
telnet commands like rrc_gNB_trigger_f1_ho
- Updated test cases in container_sa_f1_ho_b210_quectel.xml to use
the improved command without hardcoded UE ID parameter
- This makes the command more robust and easier to use in CI tests
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.
Extract the common RRC container handling logic from
ue_context_setup_request() and ue_context_modification_request() into
a new static function handle_ue_context_rrc_container().
This refactoring:
- Eliminates code duplication between the two functions
- Centralizes RRC container forwarding logic
- Improves code maintainability and consistency
Extract common CellGroupConfig encoding logic from
ue_context_setup_request() and ue_context_modification_request() into
encode_cellgroup_config().
Replace uper_encode_to_buffer() with uper_encode_to_new_buffer() to:
- Remove 1024-byte buffer size limit
- Automatically allocate correct buffer size
- Simplify code (no manual bit-to-byte conversion)
- Align with other protocol encoders
- 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
When processing UL RRC messages from PDCP, the DU association ID (assoc_id)
was not being propagated to RRC, resulting in assoc_id being 0 in
rrc_gNB_decode_dcch.
Fix by setting originInstance in the ITTI message header to the stored
du_assoc_id from ue_data when PDCP creates the F1AP_UL_RRC_MESSAGE.
Integration `2026.w04`
* !3787 CI: disable aerial x86 build pipeline
* !3820 Integrate F1AP messages required for NRPPa
* !3789 fix A3 event configuration
* !3861 add a csv T tracer
* !3669 NR UE: add neighboring cell measurements and measurement report of event A3
* !3866 nr-softmodem: ensure RU is ready before L1 init in NFAPI PNF mode
* !3402 Test FDM PRACH in CI
* !3852 Cleanup nr_slot_fep_ul
* !3782 Improvements to support CSET0 multiplexing pattern 3 for FR2
* !3862 Check for PDSCH overlapping CORESET during RA
* !3430 NR gNB handling TCI state indication for beam switching
* !3872 Fix compilation issues with vrtsim taps client
* !3687 Standardize Documentation Formatting and Navigation for MkDocs
Closes#705
See merge request oai/openairinterface5g!3867
Standardize Documentation Formatting and Navigation for MkDocs
This merge request improves and organizes the documentation to align with MkDocs
requirements. The following guidelines have been applied:
Guidelines Followed
Fix Broken Links and Paths
- Updated all links with proper paths to ensure correct rendering in MkDocs.
Correct Headings
- Removed multiple H1 headings (#).
- Subheadings use H2–H6 (## to ######) for consistent structure.
Proper URL Formatting
- All URLs now follow standard Markdown syntax,
e.g., [Example](https://www.example.com).
Proper Syntax
- Tables, lists, and code blocks use standard Markdown formatting to ensure
correct rendering.
Remove HTML Formatting
- Removed unnecessary inline HTML styling from documents, retaining only the
content.
Notes and Warnings
- Converted notes and warnings into blockquote syntax (>).
This ensures the documentation is properly structured, consistent, and
MkDocs-friendly.
- Include functions/file_names in backticks for readability
- Include the images directly inside the document (rather than plain image file name)
- Give relevant spacing if required
- Remove multiple single top-level (# H1) headings per file
- Use (# H2 and ###### H6) sub-headings for consistency
- Remove any trailing # in the headings
- This ensures proper table of contents rendering in MkDocs.
- Also removed RUN_NR_multiple_BWPs.md as it is moved to MAC usage
- bold current status for clarity and add spacing for better readability
- Wrap processes in the test setup block inside code blocks as they were rendered as GitLab issues
- Remove extra spacing in the test setup block
- Give a line in between bullet points to reflect bullet points correctly
- Split long statement into bullet points for readability
- Format the document for proper rendering
- Fix table formatting
- Use standard TOC syntax in 5GNAS
- The parser was incorrectly interpreting `</` as the start of an HTML closing tag, leading to a crash in mkdocs
- Replace with HTML entity to ensure it is treated as a plain text.
NR gNB handling TCI state indication for beam switching
This MR implements the procedure to send in DLSCH MAC-CE for TCI state
indication to UE
- if new beam is reported via SSB RSRP, gNB allocates MAC-CE with TCI
indication
- DLSCH is scheduled to be transmitted with priority
- a timer is started when receiving ACK according to the delay mandated
by standard (8.10.3 of 38.133)
- at timer expiry the gNB switches beam
Check for PDSCH overlapping CORESET during RA
CORESET 0 is configured in the configuration file by
'initialDLBWPcontrolResourceSetZero' and PDSCH TDA list is configured based on
the current BWP size.
It may happen that the user configures a 2 symbol CORESET 0 for a BWP >= 48 PRBs
(which is a valid 3GPP configuration) but in function 'nr_rrc_config_dl_tda'
this scenario is not taken in account causing an overlap between PDSCH and PDCCH
symbols during RA.
This leads to very unreliable Msg2 and Msg4 decoding at the UE, but from time to
time it succeeds, which becomes hard to identify this issue.
closes#705
Fix two issues regarding vrtsims taps client implementation:
- Incorrect #define used to enable taps socket handling
- flatbuffers package name changing between ubuntu versions
Cleanup nr_slot_fep_ul
Rename nr_slot_fep_ul to nr_symbol_fep_ul to relfect its function
Simplify logic so that the function does not require RU context and
the implementation is not dependent on the implementation of RU buffer
management.
This makes the function easier to understand and moves the responsibility
to set the correct buffer offset on the caller.
Guido Casati