[FHI72] [xran F] Handle fragmented (un)compressed packets
In both E and F, the radio-transport fragmentation is not supported, and
all the "fragmented" (not seen as fragments in the xran, only as
sections) packets contain "E-bit" equal to 1. Per spec, the value 1 for
"E-bit" signifies the last fragment of one symbol. For more info, please
see "ecpriSeqid" section in the spec.
In E:
- nRBStart and nRBSize is updated according to the sent/received packet;
- max sections = 1;
- when a packet is fragmented, the xran uses memcpy(pos, iq_data_start,
size) function, and nothing is stored in start_prbu , num_prbu ,...
In F:
- nRBStart and nRBSize is only used for C-plane messages;
- nPrbElm represents the number of sections for DL only;
- based on the nPrbElm, each section contains UP_nRBStart and UP_nRBSize
parameters which represent the start and number of PRBs in one section
or one fragment;
- when a packet is fragmented, the xran uses nSecDesc and sec_desc to
extract the packet section content, and the data is stored in
start_prbu , num_prbu ,...
Previous work on the fragmentation in F:
- #884
- !3394 - only increases the XRAN_MAX_FRAGMENT from 4 to 6, since it was
only tested with BFP 8, but not end-to-end unfortunately. But this MR
fixes all the issues.
Tested with VVDN RU, 2x2, 16 bits, 100MHz, 30kHz, MTU <= 9216 B, and
Quectel UE RM520N-GL Revision: RM520NGLAAR03A03M4G.
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
Even though the jumbo frame has 9600 bytes by the spec, the max MTU is limited to the MTU of a switch, if any used.
However, the value can be < max MTU of a switch.
This is very important for fragmentation purposes. If not properly set, the PDSCH packets will be missing.
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".
NR UE: add support for multiple RF frontends
This MR adds basic support for multiple RF-frontends at the UE.
There are multiple reasons why we might want this:
1. There might be different antennas needed for different bands (e.g. NTN or
TN antennas). These antennas might be connected to different RF-frontends.
In case of Handover, the UE needs to dynamically switch between these
RF-frontends.
2. Each rf-simulator connection carries baseband I/Q samples. To be able to
perform a handover between two cells at different frequencies, there must
be two rf-simulator connections, as the baseband channels should not
interfere and thus cannot simply be added.
3. When we want to support multiple UE simulation within one instance of
nr-uesoftmodem, and allow multiple cells and probably even handover between
these cells, we need either:
1. dedicated RF-frontends for each simulated UE, or
2. dedicated RF-frontends for each connected cell and dynamically assign
simulated UEs accordingly.
This MR implements what is needed for 1., 2. and 3.1.
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 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.
When doing analogue beamforming, the beam ID for a pre-defined beam
table is passed directly to RU and there is no need to store the beam
table in PHY.
Jaroslava Fiedlerova