Robert Schmidt
7227cfb320
N2 handover
This MR introduces full support for N2 handover, covering handover
decision, preparation, execution, and notification between source and
target NG-RAN nodes.
Key features:
1. Handover Decision & Preparation:
- Implement N2 handover decision based on UE measurement reports.
- Generate the Handover Preparation Information message, including
RRCReconfiguration.
- Send Handover Required message from the source NG-RAN to the AMF.
2. Handover Execution:
- Decode and handle the Handover Request on the target NG-RAN.
- Process the Handover Command on the source gNB, triggering
RRCReconfiguration.
- Initiate Handover Notify after successful completion.
3 NGAP & RRC Enhancements:
- Implement NGAP encoding/decoding functions for Handover Required,
Handover Request, Handover Command, Handover Failure, and Handover
Notify (3GPP TS 38.413).
- Adds NG-RAN Status Transfer support (UL/DL) for PDCP COUNT
preservation during mobility:
- support for NGAP Uplink and Downlink RAN Status Transfer messages
(TS 38.413 §9.2.3.13-14) to enable proper PDCP COUNT value
transfer during handover or recovery: NGAP encoding/decoding for
RAN Status Transfer, PDCP helpers to extract and apply COUNT (HFN
+ SN) per DRB. This aligns with TS 38.300 §9.2.3.2.1 and TS 23.502
§4.9.1.3.3, ensuring PDCP status preservation in AM.
4. Testing:
- Introduce a Telnet command to manually trigger N2 handover using UE
ID and neighbor PCI.
- Add configuration file for testing N2 handover with a target gNB.
|
OpenAirInterface documentation overview |
This is the general overview page of the OpenAirInterface documentation.
This page groups links to general information, tutorials, design documents, radio integration, and special-purpose libraries.
IMPORTANT NOTE:
Before reading this documentation, we strongly advise you to keep your own repository rebased on develop
or at least to checkout the documentation on the version of the repository you are using.
Then the documentation will better reflect the features available in your repository so that you may avoid some errors.
Beware if you previously pulled the develop branch that your repository may be now behind develop.
[[TOC]]
General
- FEATURE_SET.md: lists supported features
- GET_SOURCES.md: how to download the sources
- BUILD.md: how to build the sources
- code-style-contrib.md: overall working practices, code style, and review process
- cross-compile.md: how to cross-compile OAI for ARM
- clang-format.md: how to format the code
- sanitizers.md: how to run with ASan/UBSan/MemSAN/TSan
- environment-variables.md: the environment variables used by OAI
- tuning_and_security.md: performance and security considerations
There is some general information in the OpenAirInterface Gitlab Wiki
Tutorials
- Step-by-step tutorials to set up 5G:
- RUNMODEM.md: Generic information on how to
- Run simulators
- Run with hardware
- Specific OAI modes (phy-test, do-ra, noS1)
- (5G) Using SDAP and custom DRBs
- IF setups and arbitrary frequencies
- MIMO
- How to run OAI with O-RAN 7.2 FHI
- How to run a 5G-NSA setup
- How to run a 4G setup using L1 simulator Note: we recommend the RFsimulator
- How to use the L2 simulator
- How to use the OAI channel simulator
- How to use multiple BWPs
- How to run OAI-VNF and OAI-PNF: how to run the FAPI/nFAPI split, including some general remarks on FAPI/nFAPI.
- How to use the positioning reference signal (PRS)
- How to use device-to-device communication (D2D, 4G)
- How to run with E2 agent
- How to run the physical simulators
- How to setup OAI with Nvidia Aerial and Foxconn
- How to setup OAI with LDPC accelerators (Xilinx T2/Intel ACCs)
- How to do a handover
- How to setup gNB frequency
Legacy unmaintained files:
L2NFAPI_NOS1.md,L2NFAPI_S1.md: old L2simulator, not valid anymoreSystemX-tutorial-design.md: old, high-level documentationUL_MIMO.txt: UL-MIMO specific notes
Designs
- General software architecture notes: SW_archi.md
- Information on E1
- Information on F1
- Information on how NR nFAPI works
- Flow graph of the L1 in gNB
- L1 threads in NR-UE
- Information on gNB MAC
- Information on gNB RRC
- Information on analog beamforming implementation
- Information on the UE 5G NAS implementation
Building and running from images
- How to build images
- How to run 5G with the RFsimulator from images
- How to run 4G with the RFsimulator from images
- How to run physical simulators in OpenShift
Libraries
General
- The T tracer: a generic tracing tool (VCD, Wireshark, GUI, to save for later, ...)
- OPT: how to trace to wireshark
- The configuration module
- The logging module
- The shared object loader
- The threadpool used in L1
- The LDPC implementation is a shared library
- The time management module
Radios
Some directories under radio contain READMEs:
The other SDRs (AW2S, LimeSDR, ...) have no READMEs.
Special-purpose libraries
- OAI has two scopes: one based on Xforms and one based on imgui, described in this README
- OAI comes with an integrated telnet server to monitor and control
- OAI comes with an integrated web server
Testing
- UnitTests.md explains the unit testing setup
- Component tests are under
tests/. Currently, there is a simple CU-UP tester, see the corresponding README.md. - TESTBenches.md lists the CI setup and links to pipelines
- The CI setup uses a custom framework to run end-to-end tests.
Developer tools
- formatting is a clang-format error detection tool
- iwyu is a tool to detect
#includeerrors - docker-dev-env is a ubuntu24 docker development environment