Two changes on top of the initial MU-MIMO patch (commit 766d0a4):
1. CSI-parse fix in evaluate_cqi_report path: when maxMIMO_layers=1
(and thus ri_Restriction has only one bit set, ri_bitlen=0),
evaluate_ri_report was being skipped, leaving r_index=-1 which
trips the DevAssert(ri>=0) inside evaluate_cqi_report. Fix: when
ri_bitlen=0, pick the single allowed RI directly from the
restriction bitmap. Affects all three reportQuantity branches
(cri_RI_PMI_CQI, cri_RI_LI_PMI_CQI, cri_RI_CQI).
2. MU-MIMO scheduler: relaxed-orthogonality flag and broader
partner search:
- OAI_MU_MIMO_RELAXED=1 bypasses the strict (same-x1, x2-diff-2)
orthogonality test for testbed validation on rfsim where the
symmetric channel makes all UEs report identical PMI.
- Partner search now scans the full UE_sched (skipping leader and
already-paired entries) instead of only iterator+1; this finds
candidates regardless of PF position.
- Diagnostic LOG_W messages on partner-search entry and per-skip
reason (capped to 20 events to avoid log flood).
Findings on this w17 build with 6 UEs at 5Mbps DL each:
- Patch compiles, deploys, gNB does not crash, scheduler reaches
partner-search block on a fraction of slots.
- However eligible_others=0 in every observed partner-search entry:
PF puts only one UE in UE_sched per pf_dl call almost always,
even at cell saturation. The other attached UEs are skipped
earlier (likely HARQ pids pending feedback). So the partner
search has nothing to pair.
- Architectural conclusion: forcing concurrent multi-UE scheduling
on OAI's PF + finite-HARQ scheduler likely needs scanning
connected_ue_list (not just UE_sched), and may need broader
refactoring to pre-allocate slot resources for MU-MIMO pairs.
OpenAirInterface License
The source code is distributed under CSSL v1.0. Some files, such as for orchestration, are distributed under MIT license(MIT.txt). 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:
- CSSL v1.0 starting tag 2026.w14
- OAI Public License v1.1 starting tag v1.0 till
af4b0d53 - OAI Public License v1.0: starting tag v.04 till v1.0
- GPL 3: starting tag v.0 till v.04 (only initial implementation of 4G)
Where to Start
- General overview of documentation
- The implemented features
- System Requirements for Using OAI Stack
- How to build
- How to run the modems
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 OAI 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
.confformat only. - Logs of OAI gNB/DU/CU/CU-CP/CU-UP in
.logor.txtformat 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 GitLab, so keep checking.
Always remember a structured email will help us understand your issues quickly.
