CFRA: mark RA complete when sending Msg2
The current contention-free random access forces a "Msg3" (which does
not exist in CFRA) to be received by a UE. Sometimes, this "Msg3" is not
received (for whatever reason), and the MAC declare that RA failed.
This is problematic, as the spec says that RA is complete once Msg2 is
received by the UE. Since the gNB cannot know when this is, simply mark
it as complete once we sent Msg2.
We still send Msg3 in CFRA, which is explained further in the commits.
Also, improve logging and stabilize an RFsim test by reducing sl_ahead.
Since the parent commit, CFRA is inconditionally marked complete on Msg3
reception (successful or not). This works because the current
implementation still sends a UL grant (see parent commit for details).
In this commit, handle Msg3 if received in CFRA (notably for TA and
power). Note that since we declare RA complete, UE->ra does not exist
anymore, and so an intermediate variable is introduced to capture the
CFRA flag. The code should be such that if we are in CFRA, we never
access any UE->ra variable.
The current contention-free random access forces a "Msg3" (which does
not exist in CFRA) to be received by a UE. Sometimes, this "Msg3" is not
received (for whatever reason), and the MAC declare that RA failed.
This is problematic, as the spec says that RA is complete once Msg2 is
received by the UE. To avoid this, inconditionally mark RA as complete
as soon as we receive an indication of Msg3 (DTX or not).
Note that after this change, we still send a UL grant in Msg2. This is
because 38.321 §5.1.4 is not clear to me whether we should send UL grant
(it does not explicitly exclude it), and it says
> 3> if the Random Access Response includes a MAC subPDU with RAPID only:
> [...]
> 4> indicate the reception of an acknowledgement for SI request to
> upper layers.
which is NOT the case (but then I don't know/think we can have CFRA for
SI request?). Since it also works with COTS UE, I leave Msg3 for the
moment.
The reason to not directly mark RA as complete when sending Msg2 is
because of possible retransmissions in do-ra mode. In fact, in do-ra,
there might already be data awaiting. In that case, the DLSCH scheduler
schedules data _in the same slot as Msg2_, which the UE does not decode,
leading to retransmissions.
Implementation of STOP exchange
This implements the STOP.request/indication for all 3 transport mechanisms, the
VNF will send the STOP.request to the PNF, indicating it will disconnect, and
await a STOP.indication from the PNF
The WLS VNF is reworked to be able to start before the PNF, by calling call
rte_eal_init and rte_dev_probe to determine if dpdk has been initialized
properly, before calling rte_eal_init in the intended process when it is
appropriate to do so
Fix reestablishment after handover
- fix reestablishment by not re-creating LCIDs with priority set to 0 (see first
commit for more details)
- cleanup code
The idea is to reestablish all RLC entities (it's a new UE, and we set
reestablishRLC on all bearerrs), so we should reestablish all RLC
entities on gNB side as well, without any additional loop.
Co-authored-by: Roberto Magueta <rmagueta@allbesmart.pt>
Move the file process_addmod_bearers_cellGroupConfig() to the file where
it is used. Correctly set priorities as requested in RLC bearer
configuration.
In all cases (NSA, HO), we create LCIDs before the UE triggers random
access. Hence, process_addmod_bearers_cellGroupConfig() is not
necessary, as it just tries to recreate an LCID.
Furthermore, it includes a bug, as this function does set a wrong
priority (0), so the sorting of LCIDs is not correct. This in turn
creates problems with reestablishment, as LCID 1/SRB1 is not in the
first position, making reestablishment fail (where we assume LCID 1 be
in first position).
The actual bug of setting priorities is fixed in the next commit.
Fix MIB encoding in F1SetupRequest: use encode_MIB_NR_setup instead of encode_MIB_NR
- The DU was using encode_MIB_NR() while constructing the GNB-DU System
Information for the F1SetupRequest.
- encode_MIB_NR() encodes a full NR_BCCH_BCH_Message_t, causing the MIB to be
wrapped in a BCH container.
- This results in incorrect MIB values in the F1SetupRequest PCAP (e.g., wrong
systemFrameNumber, SCS, DMRS position, cellBarred).
- According to 3GPP TS 38.473, the MIB carried in F1AP must be encoded as a raw
NR_MIB_t.
- The correct function encode_MIB_NR_setup() encodes MIB in the required format
but was not used.
- This patch replaces encode_MIB_NR() with encode_MIB_NR_setup() to ensure correct
and standards-compliant MIB encoding in the F1SetupRequest.
Closes issue #1034.
Fix DRB integrity failures during handover and re-establishment
This MR fixes DRB integrity protection failures that occur during N2 handover
and connection re-establishment scenarios. The issues were caused by incorrect
security key handling and ciphering configuration during these procedures with
DRB integity enabled.
See merge request !3767 for more details.
Avoid measGap configuration on handover in intra-freq scenarios
During the handover, we are incorrectly configuring the measGap, even though
neighboring cells are on the same frequency. Since gNB is not expecting this
measGap, the SRS scheduling is performed. Therefore, we are periodically
receiving these logs after the handover:
[NR_MAC] Invalid timing advance offset for RNTI 58e2
[NR_MAC] Invalid timing advance offset for RNTI 58e2
[NR_MAC] Invalid timing advance offset for RNTI 58e2
[NR_MAC] Invalid timing advance offset for RNTI 58e2
[NR_MAC] Invalid timing advance offset for RNTI 58e2
[NR_MAC] Invalid timing advance offset for RNTI 58e2
These logs occur at a time when UE is performing a MeasGap operation and not
sending the SRS, while gNB thinks it will receive the SRS, but will not receive
any SRS.
This MR resolves this issue, and after the handover, these logs no longer
appear.
Use UL functions for Qm/R determination
During refactoring, the wrong functions and correspondingly tables have
been used to calculate UL TB size. Fix through correct functions.
This should fix these error messages:
3624774.778195 [MAC] E (nr_get_Qm_dl:2034) Invalid MCS table index 3 (expected in range [0,2])
3624774.778207 [MAC] E (nr_get_code_rate_dl:2066) Invalid MCS table index 3 (expected in range [0,2])
3624774.778211 [NR_MAC] E (nr_compute_tbs:63) Error in compute TBS with a NULL input, returning NULL TBS
Fixes: 9449f777 ("Remove TBS table and recompute on demand")
During refactoring, the wrong functions and correspondingly tables have
been used to calculate UL TB size. Fix through correct functions.
This should fix these error messages:
3624774.778195 [MAC] E (nr_get_Qm_dl:2034) Invalid MCS table index 3 (expected in range [0,2])
3624774.778207 [MAC] E (nr_get_code_rate_dl:2066) Invalid MCS table index 3 (expected in range [0,2])
3624774.778211 [NR_MAC] E (nr_compute_tbs:63) Error in compute TBS with a NULL input, returning NULL TBS
Fixes: 9449f777cc ("Remove TBS table and recompute on demand")
- The DU was using encode_MIB_NR() while constructing the GNB-DU System Information for the F1SetupRequest.
- encode_MIB_NR() encodes a full NR_BCCH_BCH_Message_t, causing the MIB to be wrapped in a BCH container.
- This results in incorrect MIB values in the F1SetupRequest PCAP (e.g., wrong systemFrameNumber, SCS, DMRS position, cellBarred).
- According to 3GPP TS 38.473, the MIB carried in F1AP must be encoded as a raw NR_MIB_t.
- The correct function encode_MIB_NR_setup() encodes MIB in the required format but was not used.
- This patch replaces encode_MIB_NR() with encode_MIB_NR_setup() to ensure correct and standards-compliant MIB encoding in the F1SetupRequest.
Closes issue #1034.
Problem:
During N2 handover with integrity protection (NIA1/NIA2), the target gNB
was disabling ciphering when configuring SRB1 security, while the UE
continued using the old security context from the source gNB until it
received and processed the RRC Reconfiguration with masterKeyUpdate. The
first PDUs sent after CFRA were still ciphered with the old keys, but the
target gNB had ciphering disabled, causing it to skip deciphering and
attempt integrity verification on ciphered data, leading to MAC-I
mismatches and integrity failures.
Specification Reference:
According to TS 33.501 section 6.11, "the UE shall keep the K gNB used in
the source cell until the handover or a connection re-establishment has been
completed successfully". This means the UE continues using the old security
context (old KRRCint, KRRCenc) until it receives and processes the RRC
Reconfiguration with masterKeyUpdate. The target gNB must therefore enable
ciphering during handover setup to correctly decipher and verify integrity
of PDUs sent with the old security context before the UE switches to the new
keys.
Root Cause:
The code was calling nr_rrc_pdcp_config_security(UE, false) during
handover setup, which disabled ciphering. This was incorrect because:
1. The UE already has security active from the source gNB
2. The UE continues using old ciphered keys until masterKeyUpdate
3. The UE sends ciphered PDUs immediately after CFRA succeeds
4. The target gNB must be able to decipher these PDUs to verify integrity
Why it only manifested when drb_integrity = "yes":
The bug was always present, but only caused visible failures when
integrity verification was enabled. When drb_integrity = "no", the config
typically also sets integrity_algorithms to only NIA0, resulting in
UE->integrity_algorithm = 0, which causes has_integrity = 0 for SRB1,
skipping integrity verification and hiding the underlying ciphering bug.
When drb_integrity = "yes", integrity_algorithms typically includes
NIA1/NIA2, resulting in has_integrity = 1 for SRB1, causing integrity
checks to run on ciphered data and fail.
Fix:
Change nr_rrc_pdcp_config_security(UE, false) to
nr_rrc_pdcp_config_security(UE, true) during handover setup to enable
ciphering immediately, allowing the target gNB to correctly decipher and
verify integrity of PDUs sent with the old security context.
Note: This fix is specific to handover. During initial context setup,
ciphering should remain disabled until SecurityModeComplete is received,
as the UE hasn't activated ciphering yet at that point.
During re-establishment, new KgNB* is derived, requiring new UP keys (KUPint,
KUPenc) to be sent to CU-UP. When do_drb_integrity = true, CU-UP needs the
updated integrity keys to verify DRB PDUs. Without this update, CU-UP uses
old keys while the UE uses new keys, causing integrity failures.
The fix ensures security info is always sent during re-establishment,
which is critical for DRB integrity.
In case of Handover, NTNconfig sent in RRCreconfiguration triggering handover contains epoch time wrt
timing of Target cell. NTNconfig in RRC needs to be processed only after timing is acquired on the target cell
In case of Target cell, epoch time is the sfn nearest to the frame timing of the target cell.
PDU Session Release
This MR implements end-to-end PDU Session Release functionality
according to 3GPP TS 38.413 and TS 38.331 specifications.
Reason for Change Previous implementation had incomplete and wrongly
places tunnel cleanup during PDU session release. UP cleanup shall be
done at CUUP, RRCReconfiguration shall be sent after retrieval of
updated CellGroupConfig from the DU. This implies F1 and E1 exchanges
during PDU session release procedure.
Major Changes:
1. RRC PDU Session Release: DRBs and PDU session teardown in NGAP PDU
Session Release Response callback
- Helper Functions: Introduced rm_pduSession,
find_drb_by_pdusession_id and rm_drbs() helpers to locate and clean
up DRBs linked to a specific PDU session
- Targeted Cleanup: RRC PDU Session and per-session DRB removal in
rrc_gNB_send_NGAP_PDUSESSION_RELEASE_RESPONSE()
- Status Cleanup: Removed unused PDU_SESSION_STATUS_RELEASED status
2. RRC PDU Session Release: Refactor
rrc_gNB_process_NGAP_PDUSESSION_RELEASE_COMMAND
- Any PDU session in the pdusession_release_params list that is
present in the RRC list can be set to release, regardless of its
status
- Function Signature Update: Updated function signature and other
minor changes
- Response Handling: rrc_gNB_send_NGAP_PDUSESSION_RELEASE_RESPONSE is
sent upon completion of RRCReconfiguration
3. RRC PDU Session Release: add missing procedures E1AP Integration:
- Populates E1AP Bearer Modification for each to be released session
- PDCP Enhancement: Added nr_pdcp_release_drbs() to remove all DRBs
linked to a given PDU session in CUUP
- GTP-U Cleanup: GTP tunnel teardown handled in CUUP
e1_bearer_context_modif() using correct F1 or N3 GTP instance
4. NR PDCP/GTP:
- Enhanced Tunnel Deletion Logic: Separate handling for N3 tunnels (1
per PDU session) and F1-U tunnels (1 per DRB)
- New PDCP API Function: Added nr_pdcp_get_drb_ids_for_pdusession()
function to retrieve all DRB IDs associated with a specific PDU
session
5. RRC PDU Session Release: F1AP-based UE Context Modification:
- Replaced direct RRC message transfer with F1AP UE Context
Modification Request for proper retrieval from DU
- Cell Group Configuration: handling of updated CellGroupConfig from
DU ensures DRB release at CU
6. Docs and testing:
- Added PDU session add/remove test cases to 25 PRB RFSIM pipeline
- Documentation: Added PDU Session Release sequence diagram
- Telnet Commands: Added ci command to trigger NGAP PDU Session
Release and ciUE command to trigger establishment of a new PDU
Session
7. Additional fixes:
- UE RLC Management: ensure release of RLC entities
- Unify NG delay control before calling the RRC NGAP handler, for both
Setup and Release
8. Code Cleanup: Cleaned up unused GTP teardown functions.
Closes#867
- Add delayed_action_state_t in the UE context for ongoing delayed action
- Move delay check and timer re-enqueue to rrc thread in rrc_gNB.c (rrc_delay_transaction)
- Call delay before NGAP setup/release handlers; remove local delay logic from rrc_gNB_NGAP.c
- Clear on RRCReconfigurationComplete (reset_delayed_action)
Closes#960
We need to keep PDU sessions and DRBs in list until the NGAP PDU Session Release Response is sent.
* Introduced find_drb() and remove_drbs_by_pdu_session() helpers to locate
and clean up DRBs linked to a specific PDU session
* Targeted per-session DRB removal in rrc_gNB_send_NGAP_PDUSESSION_RELEASE_RESPONSE()
* Ensures DRBs for unaffected PDU sessions remain intact
* Remove unused PDU_SESSION_STATUS_RELEASED status: keeping this status is no longer relevant
since the PDU sessions are effectively removed from the RRC lists
Closes#867
Also, refactor rrc_gNB_process_NGAP_PDUSESSION_RELEASE_COMMAND
3GPP TS 38.413 8.2.2 PDU Session Resource Release says:
> upon reception the NG-RAN node shall execute the release of the requested PDU sessions.
> For each PDU session to be released the NG-RAN node shall release the corresponding
> resources over Uu and over NG, if any.
Therefore, any PDU session in the pdusession_release_params list that is
also present in the RRC list can be set to release, regardless of its status.
The function signature was also updated along with other minor changes.
This commit implements proper PDU Session Release handling across
RRC, PDCP, F1AP, E1AP to ensure clean resource cleanup when
a PDU session is terminated.
Key changes:
NGAP:
In `rrc_gNB_process_NGAP_PDUSESSION_RELEASE_COMMAND()`:
* Populates E1AP Bearer Modification for each released session
* If a CU-UP is connected, triggers `bearer_context_mod()` for PDU teardown
PDCP:
* Added `nr_pdcp_release_drbs()` to remove all DRBs linked to a given PDU session
* Called from `e1_bearer_context_modif()` for correct clean-up during session release
F1AP UE Context Modification:
Replace direct RRC message transfer with F1AP UE Context Modification Request
to properly handle PDU session release according to 3GPP TS 38.331.
3GPP TS 38.331 `5.3.5.6.4 DRB release` says: whether or not the RLC and MAC entities associated
with a PDCP entity are reset or released is determined by the CellGroupConfig. Thus,
updated CellGroupConfig needs to be received by the UE. This has to be retrieved by CUCP
from the DU. Therefore:
After receiving an NGAP_PDUSESSION_RELEASE_COMMAND, the CUCP shall:
1) forward (store for later) the NAS PDU to the UE, if present as per 3GPP TS 38.413, and
2) send a UE Context Modification to the DU with the list of DRBs to release
and the RRC container (RRCReconfiguration with NAS PDU)
After reception of UE Context Modification Response, the list of drbs to release
is prepared based on PDU session status PDU_SESSION_STATUS_TORELEASE
in rrc_gNB_generate_dedicatedRRCReconfiguration and then encoded
in drb_ToReleaseList for a new RRCReconfiguration with the new cellGroupConfig.
Key changes:
* rrc_gNB_generate_dedicatedRRCReconfiguration_release() now uses F1AP UE Context
Modification Request instead of direct RRC transfer
* Only DRBs to be released are now added to the list.
* The ASN.1 memory allocation is entirely done in build_RRCReconfiguration_IEs
* No longer needed to store ASN1 struct in UE context
GTP-U:
* Previous implementation had incomplete tunnel cleanup during PDU session release
- Missing distinction between N3 (PDU session level) and F1-U (DRB level) tunnels
- Lack of proper DRB identification for F1-U tunnel deletion
Major Changes:
* GTP tunnel teardown now handled in `e1_bearer_context_modif()` using the correct
F1 or N3 GTP instance (`newGtpuDeleteOneTunnel()`)
* Enhanced Tunnel Deletion Logic (cucp_cuup_handler.c):
- Separate handling for N3 tunnels (1 per PDU session) and F1-U tunnels (1 per DRB)
- Added proper DRB identification for F1-U tunnel cleanup
- Improved error handling with detailed logging for each tunnel deletion
- Enhanced logging to distinguish between N3 and F1-U tunnel operations
* New PDCP API Function (nr_pdcp_oai_api.c/h):
- Added nr_pdcp_get_drb_ids_for_pdusession() function
- Enables retrieval of all DRB IDs associated with a specific PDU session
- Supports proper F1-U tunnel cleanup by providing DRB identifiers in CUUP
* Enhanced GTP Interface (gtp_itf.cpp/h):
- Modified newGtpuDeleteOneTunnel() to accept tunnel_type parameter
- Improved logging to distinguish between PDU session and DRB tunnel types
- Better error messages for tunnel deletion failures
- Enhanced debugging information for remaining tunnels
Clean-up:
* Ensured xid tracking works consistently between PDU Session Establishment (with NAS PDU)
and dedicated RRCReconfiguration
* Add function to release GTP-U tunnel in Bearer Context Modification Request handler
* Do not send rrc_gNB_send_NGAP_PDUSESSION_RELEASE_RESPONSE when no PDU session are to
be released: it is sent upon completion of the RRCReconfiguration and needs to contain
released PDU Sessions (mandatory IE), therefore it is no necessary to send it in case
there is no PDU session to release.
Related to #867
Co-authored-by: rmagueta <rmagueta@allbesmart.pt>
gNB: modify RLC configuration applied for SRB1 during RRCReestablishment
TS 38.331 clause 5.3.7.4 specifies to apply the configuration defined in
9.2.1 for SRB1 at UE side. This implies that the gNB also has to apply
sn_field_length = 12, but there are no implications on the other RLC
parameters.
As wrong timer values break SRB1 e.g. for long RTT NTN scenarios, this
commit switches to using the RLC timer values provided in the
configuration file. Currently we still set poll_pdu, poll_byte and
max_retx_threshold to the values defined in 9.2.1, but this can be
changed.
Remove schedule response and update L1 threading documentation
This merge requests removes the somewhat superfluous "schedule response"
mechanism. "schedule response" was run after running the scheduler
itself and copied various FAPI messages into a global msgDataTx
structure from which the various TX/RX jobs were triggered. It is not
necessary, though, given that the scheduler is run inside the tx_func()
(running the TX jobs of the L1), and so the scheduler output FAPI
messages can directly be read into a variable of the existing
NR_Sched_Rsp_t type. This allows to delete a couple of hundred lines of
code (while retaining functionality), and simplifies the msgDataTx type
(which is still there to trigger TX job (including the scheduler) from
the ru thread).
In short, prior, there was this call chain:
- tx_func() calls run_scheduler_monolithic() (through fptr
NR_slot_indication())
- get some memory through allocate_sched_response() which has enough
space for NR_Sched_Rsp_t type variable
- call the scheduler and fill the variable
- call nr_schedule_response() (through fptr NR_schedule_response())
which copies into L1: to msgDataTx for TX, to separate structures
for RX
this is changed to
- tx_func() runs one message at a time, hence we can use memory in the
data segment for NR_Sched_Rsp_t. It calls run_scheduler_monolithic()
through the fptr
- pointers into NR_Sched_Rsp_t are passed to the scheduler, which
fills as before
- we return, memory is in its right place and does not need an extra
copy.
Additionally, this merge request updates documentation on threading and
cleans up some unused code along the way.
Reimplement nFAPI message exchange between L1 and L2 following the
changes in parent commit removing msgDataTx.
Avoid direct calls and use NR_IF_module fptrs to avoid linking problems.
allowing to remove some function definitions that are not needed.
Note: after this commit, monolithic works but nFAPI operation is broken
and fixed in the next commit, to keep the changes small(er). All
simulators work.
This commit removes the use of msgDataTx's intermediate buffers for FAPI
messages and the call of the "Schedule response". The latter incurs an
additional copy of FAPI messages for the TX chain (for the RX chain, it
is and will remain there) which we can avoid.
Instead, it uses an NR_Sched_Rsp_t-typed variable sched_response to
store the results of the scheduler when called from tx_func(). Thus, the
scheduler remains unchanged (it gets a pointer to where to put FAPI
messages), but we don't call nr_schedule_response() to then copy FAPI
messages into the L1, but have them in a local variable sched_response.
sched_response on on the data segment, as it is big and would overflow
the stack; at the same time, this is ok because only one tx_func() runs
at a time.
Since we don't use allocate_sched_response() anymore, we don't need
deref_sched_response().
clear_slot_beamid() is moved to tx_func(), as it was called in
nr_schedule_response().
Since the "intermediate" NR_gNB_DLSCH_t structure groups both the
DL_tti_pdsch and TX_data.req structures, a pointer has been created to
point to pdsch_pdu. This affects a number of simulators, as they have to
put some messages on the stack:
- nr_dlschsim: put the corresponding variable on the stack
- nr_pbchsim: a new array for the SSB PDUs has been introduced
Further, these changes are now necessary:
- nr_dlsim: there were variables "rel15" and "pdsch_pdu_rel15" that
point to the same PDSCH PDU. At least "rel15" would not exist, as the
corresponding pointer is now populated in phy_procedures_gNB_TX(), and
we therefore refer to the single PDSCH PDU variable with
"pdsch_pdu_rel15", but at the place where "rel15" used to be
initialized.
- nr_ulsim: use nr_save_ul_tti_req() to load PDUs into the RX chain
instead of nr_schedule_response(), which does not exist anymore.
TS 38.331 clause 5.3.7.4 specifies to apply the configuration defined in 9.2.1 for SRB1 at UE side.
This implies that the gNB also has to apply sn_field_length = 12, but there are no implications on the other RLC parameters.
As wrong timer values break SRB1 e.g. for long RTT NTN scenarios, this commit switches to using the RLC timer values provided in the configuration file.
Currently we still set poll_pdu, poll_byte and max_retx_threshold to the values defined in 9.2.1, but this can be changed.
maki
Robert Schmidt