Robert Schmidt 633b6de92a Merge remote-tracking branch 'venkatareddy453/ngap-pathswitch-and-ack-for-xnho' into integration_2026_w26
NGAP Procedures for Xn Handover: Path Switch Request Path Switch Request Acknowledge (#194)

This PR adds the following NGAP Path Switch procedures to support Xn
handover in accordance with 3GPP TS 38.413v16.2.0.

NGAP Path Switch Request: add encode and ITTI support

- Add a case in TASK_NGAP to support ITTI message from RRC to NGAP
- Add Path Switch Request message type definitions
- Implement encoder for Path Switch Request (3GPP TS 38.413v16.2.0
  §9.2.3.8)
  * RAN UE NGAP ID (M)
  * Source AMF UE NGAP ID (M)
  * User Location Information (M)
  * UE Security Capabilities (M)
  * PDU Session Resource to be Switched in Downlink List (M)
- Add required ASN.1 header includes for Path Switch Request IEs

NGAP Path Switch Request Acknowledge: add decode and handler

- Add handler at NGAP for Path Switch Request Acknowledge from AMF
- Add Path Switch Request Acknowledge message type definitions
- Implement decoder for Path Switch Request Acknowledge (3GPP TS
  38.413v16.2.0 §9.2.3.9)
  * AMF UE NGAP ID (M)
  * RAN UE NGAP ID (M)
  * Security Context (M)
  * PDU Session Resource Switched List (M)
  * Allowed NSSAI (M)
- Add required ASN.1 header includes for Path Switch Request Acknowledge
  IEs

Notes:

- Added a case NGAP_PATH_SWITCH_REQ in task_ngap to support ITTI message
  from RRC, and this will be allocated at
- RRC when the target gNB receives the RRC complete message from the UE
  during Xn handover.
- OAI CN5G does not support any of the NGAP path switch procedures
  (request, ack, and failure) as of today to test Xn Handover.
- We tested the procedures in an E2E setup at IISc with two gNBs in
  E1+F1+7.2x split containing the Xn handover code and connected to the
  same 5G core (used Open5GS & Aether-OnRamp separately), and also did
  not observe any Path Switch Failure.
- The implementation of Path Switch Failure at OAI RAN will be done
  along with the implementation of Path Switch procedures in OAI CN5G
  once the XNAP integration in OAI RAN is complete.

Acknowledgement:

> This work has been partially carried out as part of Xn Handover
development at the Indian Institute of Science (IISc), Bengaluru.

Reviewed-by: Robert Schmidt <robert.schmidt@openairinterface.org>
Reviewed-By: Guido Casati <guido.casati@openairinterface.org>
2026-06-29 09:17:07 +02:00
2023-08-23 17:15:48 +02:00
2024-10-11 09:12:49 +02:00
2024-03-08 15:53:42 +01:00
2026-04-22 22:34:02 +02:00
2022-10-18 15:24:48 +02:00
2026-06-18 16:38:51 +02:00

Duranta OAI

License Supported OS Ubuntu 22 Supported OS Ubuntu 24 Supported OS Ubuntu 26 Supported OS RHEL9 Supported OS Fedora 44

Docker Pulls Docker Pulls Docker Pulls Docker Pulls Docker Pulls

Duranta - OpenAirInterface

Duranta OpenAirInterface RAN delivers and maintains an open-source cellular wireless software stack for 4G, 5G and future networking technologies. It supports simulation, prototyping, and end-to-end deployments on Commercial-Off-The-Shelf (COTS) hardware. Built for research and experimentation, it provides standard-compliant interfaces and is released under the Collaborative Standards Software License (CSSL).

License

The source code is distributed under CSSL v1.0. Some files, such as for orchestration, are distributed under MIT license. Documentation is distributed under Creative Commons Attribution 4.0 International license.

All the files without an explicit copyright header have an implicit "Copyright of OpenAirInterface Authors".

Please see NOTICE for other licenses which are used in the software.

In the past OAI source code has been re-licensed sometimes, here is the history:

  1. CSSL v1.0 starting tag 2026.w14
  2. OAI Public License v1.1 starting tag v1.0 till af4b0d53
  3. OAI Public License v1.0: starting tag v.04 till v1.0
  4. GPL 3: starting tag v.0 till v.04 (only initial implementation of 4G)

Where to Start

Not all information is available in a central place, and information for specific sub-systems might be available in the corresponding sub-directories. To find all READMEs, this command might be handy:

find . -iname "readme*"

RAN repository structure

The OpenAirInterface (OAI) software is composed of the following parts:

openairinterface5g
├── charts
├── ci-scripts        : Meta-scripts used by the OSA CI process. Contains also configuration files used day-to-day by CI.
├── CMakeLists.txt    : Top-level CMakeLists.txt for building
├── cmake_targets     : Build utilities to compile (simulation, emulation and real-time platforms), and generated build files.
├── common            : Some common OAI utilities, some other tools can be found at openair2/UTILS.
├── doc               : Documentation
├── docker            : Dockerfiles to build for Ubuntu and RHEL
├── executables       : Top-level executable source files (gNB, eNB, ...)
├── maketags          : Script to generate emacs tags.
├── nfapi             : (n)FAPI code for MAC-PHY interface
├── openair1          : Layer 1 (3GPP LTE Rel-10/12 PHY, NR Rel-15 PHY)
├── openair2          : Layer 2 (3GPP LTE Rel-10 MAC/RLC/PDCP/RRC/X2AP, LTE Rel-14 M2AP, NR Rel-15+ MAC/RLC/PDCP/SDAP/RRC/X2AP/F1AP/E1AP), E2AP
├── openair3          : Layer 3 (3GPP LTE Rel-10 S1AP/GTP, NR Rel-15 NGAP/GTP)
├── openshift         : OpenShift helm charts for some deployment options of OAI
├── radio             : Drivers for various radios such as USRP, AW2S, RFsim, 7.2 FHI, ...
├── targets           : Some configuration files; only historical relevance, and might be deleted in the future
└── tools             : Tools for use by the developers/ci machines: code analysis and formatting

How to get support from the Community

You can ask your question on the mailing lists.

Your email should contain below information:

  • A clear subject in your email.
  • For all the queries there should be [Query] in the subject of the email and for problems there should be [Problem].
  • In case of a problem, add a small description.
  • Do not share any photos unless you want to share a diagram.
  • OAI gNB/DU/CU/CU-CP/CU-UP configuration file in .conf format only.
  • Logs of OAI gNB/DU/CU/CU-CP/CU-UP in .log or .txt format only.
  • In case your question is related to performance, include a small description of the machine (Operating System, Kernel version, CPU, RAM and networking card) and diagram of your testing environment.
  • Known/open issues are present on Github, so keep checking.

Always remember a structured email will help us understand your issues quickly.

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