LDPC offload with the XDMA driver

• LDPC offload with the XDMA driver
  • XDMA Driver Build & Install
  • OAI Build
  • 5G PHY simulators
    • nr_ulsim test
  • Run
    • gNB
    • UE

This documentation aims to provide a tutorial for using Xilinx PCIe-XDMA based FPGA LDPC decoding within OAI. LDPC decoding is offloaded to FPGA.

XDMA Driver Build & Install

• Get XDMA driver source

  git clone https://github.com/Xilinx/dma_ip_drivers.git
  cd dma_ip_drivers/XDMA/linux-kernel
  

  The xdma_driver directory contains the following:

dma_ip_drivers/XDMA/linux-kernel/
├── COPYING
├── include
├── LICENSE
├── readme.txt
├── RELEASE
├── tests
├── tools
└── xdma

Before building the driver, ensure that your system recognizes the Xilinx device. You can check this using the lspci command:

$ lspci | grep Xilinx
01:00.0 Serial controller: Xilinx Corporation Device 8038

Building and Installing the Driver

cd ~/dma_ip_drivers/XDMA/linux-kernel/xdma
make clean
make
# install to make the driver loading automatically at system startup
sudo make install

Load the Driver

cd ~/dma_ip_drivers/XDMA/linux-kernel/tests
sudo ./load_driver.sh

OAI Build

# Get openairinterface5g source code
git clone https://gitlab.eurecom.fr/oai/openairinterface5g.git ~/openairinterface5g
cd ~/openairinterface5g

# Install OAI dependencies
cd ~/openairinterface5g/cmake_targets
./build_oai -I

# Build OAI gNB & UE
cd ~/openairinterface5g
source oaienv
cd cmake_targets
./build_oai --ninja -w SIMU --gNB --nrUE -P --build-lib "ldpc_xdma" -C -c

Shared object file libldpc_xdma.so is created during the compilation. This object is conditionally compiled. Selection of the library to compile is done using --build-lib ldpc_xdma.

5G PHY simulators

The simulated test uses the option --loader.ldpc.shlibversion _xdma to select the XDMA version for loading into the LDPC interface. Additionally, the option --nrLDPC_coding_xdma.num_threads_prepare is used to specify the number of threads for preparing data before the LDPC processing, specifically for the deinterleaving and rate matching parts.

Another way to activate the feature is to add the xdma.conf file with the following content:

nrLDPC_coding_xdma : {
  num_threads_prepare : 2;
};

loader : {
  ldpc : {
    shlibversion : "_xdma";
  };
};

and use option -O xdma.conf.

nr_ulsim test

Example command for running nr_ulsim with LDPC decoding offload to the FPGA:

cd ~/openairinterface5g/cmake_targets/ran_build/build
sudo ./nr_ulsim -n100 -m28 -r273 -R273 -s22 -I10 -C8 -P --loader.ldpc.shlibversion _xdma --nrLDPC_coding_xdma.num_threads_prepare 2

or

sudo ./nr_ulsim -n100 -m28 -r273 -R273 -s22 -I10 -C8 -P -O xdma.conf

Run

Both gNB and nrUE use the option --loader.ldpc.shlibversion _xdma to select the XDMA version for loading into the LDPC interface and --nrLDPC_coding_xdma.num_threads_prepare to specify the number of threads for preparing data before the LDPC processing, specifically for the deinterleaving and rate matching parts.

Another way to activate the feature is to add the following content to the .conf file you want to use:

nrLDPC_coding_xdma : {
  num_threads_prepare : 2;
};

loader : {
  ldpc : {
    shlibversion : "_xdma";
  };
};

and use option -O *.conf.

gNB

Example command using rfsim:

cd ~/openairinterface5g/cmake_targets/ran_build/build
sudo ./nr-softmodem --rfsim --log_config.global_log_options level,nocolor,time -O ../../../ci-scripts/conf_files/gnb.sa.band78.106prb.rfsim.conf --loader.ldpc.shlibversion _xdma --nrLDPC_coding_xdma.num_threads_prepare 2

or

sudo ./nr-softmodem --rfsim --log_config.global_log_options level,nocolor,time -O ../../../ci-scripts/conf_files/gnb.sa.band78.106prb.rfsim.conf

if you have added the configuration to the .conf file.

UE

Example command using rfsim:

cd ~/openairinterface5g/cmake_targets/ran_build/build
sudo ./nr-uesoftmodem --rfsim -r 106 --numerology 1 --band 78 -C 3319680000 --ue-nb-ant-tx 1 --ue-nb-ant-rx 1 -O ../../../ci-scripts/conf_files/nrue1.uicc.cluCN.conf --rfsimulator.serveraddr 10.201.1.100 --loader.ldpc.shlibversion _xdma --nrLDPC_coding_xdma.num_threads_prepare 2

or

sudo ./nr-uesoftmodem --rfsim -r 106 --numerology 1 --band 78 -C 3319680000 --ue-nb-ant-tx 1 --ue-nb-ant-rx 1 -O ../../../ci-scripts/conf_files/nrue1.uicc.cluCN.conf --rfsimulator.serveraddr 10.201.1.100

if you have added the configuration to the .conf file.