Merge remote-tracking branch 'origin/multipath-testing-ci' into integration_2026_w07 (!3886)

Integrate GPU-Accelerated Channel Simulation + CI Test Pipeline

This MR builds on top of MR !3588 (feat: GPU Accelerated Channel
Simulation Pipeline).

The main portion of the changes is directly taken from MR !3588, and
focuses on integrating the GPU-accelerated channel simulation. On top of
that, this MR adds CI-related configurations to introduce a new channel
simulation testing pipeline into the CI --> RAN-Channel-Simulation

This MR introduces a CUDA-based pipeline to offload the
multipath_channel and add_noise channel simulation functions to the GPU.
This enables large-scale, real-time physical layer simulations not
possible on the CPU.

For full documentation, please see the file at openair1/SIMULATION/TOOLS/DOC/gpu_acceleration.md.

System & Compiler Requirements: An NVIDIA GPU with a compatible driver
and the CUDA Toolkit installed.

This feature was developed and tested on the GH200 server using the GCC
12 toolchain. To ensure reproducibility, building with GCC 12 is highly
recommended.  Build Instructions

The primary flag to enable this feature is -DCUDA_ENABLE=ON. The
following command shows a sample configuration used during development
on the GH200 server:

    ./build_oai --phy_simulators --cmake-opt "\
      -DCUDA_ENABLE=ON \
      -DUSE_UNIFIED_MEMORY=ON \
      -DUSE_ATS_MEMORY=OFF \
      -DCMAKE_C_COMPILER=/usr/bin/gcc-12 \
      -DCMAKE_CXX_COMPILER=/usr/bin/g++-12 \
      -DENABLE_TESTS=ON"

Memory Model Configuration

The pipeline supports multiple CUDA memory management modes, which can
be configured at compile time. ATS Memory (-DUSE_ATS_MEMORY=ON) is
enabled by default. To use another memory model, you must first disable
ATS.

For a detailed explanation of these models, please refer to Section 3 of
the gpu_acceleration.md report.

doc/README.md

@@ -44,6 +44,7 @@ There is some general information in the [OpenAirInterface Gitlab Wiki](https://
 - [How to run a 4G setup using L1 simulator](./L1SIM.md) _Note: we recommend the RFsimulator_
 - [How to use the L2 simulator](./L2NFAPI.md)
 - [How to use the OAI channel simulator](../openair1/SIMULATION/TOOLS/DOC/channel_simulation.md)
+- [How to use GPU-accelerated channel simulation](../openair1/SIMULATION/TOOLS/DOC/gpu_acceleration.md)
 - [How to use multiple BWPs](./RUN_NR_multiple_BWPs.md)
 - [How to run OAI-VNF and OAI-PNF](./nfapi.md): how to run the FAPI/nFAPI split,
   including some general remarks on FAPI/nFAPI.

doc/TESTBenches.md

@@ -234,6 +234,10 @@ information on how the images are built.
   - groot (CU+DU0) + B210, rocket (DU1) + B210, raspix (Quectel RM520N UE), OAI CN5G
   - OpenShift cluster for CN deployment
   - Attenuator (mini circuits RC4DAT-6G-60) - controlled from rocket
+- [RAN-Channel-Simulation](https://jenkins-oai.eurecom.fr/job/RAN-Channel-Simulation/)
+  ~5G-NR
+  - gracehopper1-oai
+  - run channel simulation on CPU and GPU using test_channel_scalability
 
 ### RAN-CI-NSA-Trigger