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      <a href="http://www.openairinterface.org/">
         <img src="./images/oai_final_logo.png" alt="" border=3 height=50 width=150>
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      <b><font size = "5">OAI 5G NR SA tutorial with COTS UE</font></b>
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**Table of Contents**

[[_TOC_]]

#  1. Scenario
In this tutorial we describe how to configure and run a 5G end-to-end setup with OAI CN5G, OAI gNB and COTS UE.

Minimum hardware requirements:
- Laptop/Desktop/Server for OAI CN5G and OAI gNB
    - Operating System: [Ubuntu 22.04 LTS](https://releases.ubuntu.com/22.04/ubuntu-22.04.3-desktop-amd64.iso)
    - CPU: 8 cores x86_64 @ 3.5 GHz
    - RAM: 32 GB
- Laptop for UE
    - Operating System: Microsoft Windows 10 x64
    - CPU: 4 cores x86_64
    - RAM: 8 GB
    - Windows driver for Quectel MUST be equal or higher than version **2.4.6**
- [USRP B210](https://www.ettus.com/all-products/ub210-kit/), [USRP N300](https://www.ettus.com/all-products/USRP-N300/) or [USRP X300](https://www.ettus.com/all-products/x300-kit/)
    - Please identify the network interface(s) on which the USRP is connected and update the gNB configuration file
- Quectel RM500Q
    - Module, M.2 to USB adapter, antennas and SIM card
    - Firmware version of Quectel MUST be equal or higher than **RM500QGLABR11A06M4G**


# 2. OAI CN5G

## 2.1 OAI CN5G pre-requisites

Please install and configure OAI CN5G as described here:
[OAI CN5G](NR_SA_Tutorial_OAI_CN5G.md)


## 2.2  SIM Card
Program UICC/SIM Card with [Open Cells Project](https://open-cells.com/) programming tool [uicc-v3.3](https://open-cells.com/d5138782a8739209ec5760865b1e53b0/uicc-v3.3.tgz).

```bash
sudo ./program_uicc --adm 12345678 --imsi 001010000000001 --isdn 00000001 --acc 0001 --key fec86ba6eb707ed08905757b1bb44b8f --opc C42449363BBAD02B66D16BC975D77CC1 -spn "OpenAirInterface" --authenticate
```


# 3. OAI gNB

## 3.1 OAI gNB pre-requisites

### Build UHD from source
```bash
# https://files.ettus.com/manual/page_build_guide.html
sudo apt install -y autoconf automake build-essential ccache cmake cpufrequtils doxygen ethtool g++ git inetutils-tools libboost-all-dev libncurses5 libncurses5-dev libusb-1.0-0 libusb-1.0-0-dev libusb-dev python3-dev python3-mako python3-numpy python3-requests python3-scipy python3-setuptools python3-ruamel.yaml

git clone https://github.com/EttusResearch/uhd.git ~/uhd
cd ~/uhd
git checkout v4.6.0.0
cd host
mkdir build
cd build
cmake ../
make -j $(nproc)
make test # This step is optional
sudo make install
sudo ldconfig
sudo uhd_images_downloader
```

## 3.2 Build OAI gNB

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

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

# Build OAI gNB
cd ~/openairinterface5g/cmake_targets
./build_oai -w USRP --ninja --gNB -C
```

# 4. Run OAI CN5G and OAI gNB

## 4.1 Run OAI CN5G

```bash
cd ~/oai-cn5g
docker compose up -d
```

## 4.2 Run OAI gNB

### USRP B210
```bash
cd ~/openairinterface5g/cmake_targets/ran_build/build
sudo ./nr-softmodem -O ../../../targets/PROJECTS/GENERIC-NR-5GC/CONF/gnb.sa.band78.fr1.106PRB.usrpb210.conf --sa -E --continuous-tx
```
### USRP N300
```bash
cd ~/openairinterface5g/cmake_targets/ran_build/build
sudo ./nr-softmodem -O ../../../targets/PROJECTS/GENERIC-NR-5GC/CONF/gnb.sa.band77.fr1.273PRB.2x2.usrpn300.conf --sa --usrp-tx-thread-config 1
```

### USRP X300
```bash
cd ~/openairinterface5g/cmake_targets/ran_build/build
sudo ./nr-softmodem -O ../../../targets/PROJECTS/GENERIC-NR-5GC/CONF/gnb.sa.band77.fr1.273PRB.2x2.usrpn300.conf --sa --usrp-tx-thread-config 1 -E --continuous-tx
```

# 5. Run UE
## 5.1 Testing with Quectel RM500Q

### 5.1.1 Setup Quectel
With [PuTTY](https://the.earth.li/~sgtatham/putty/latest/w64/putty.exe), send the following AT commands to the module using a serial interface (ex: COM2) at 115200 bps:
```bash
# MUST be sent at least once everytime there is a firmware upgrade!
AT+CGDCONT=1,"IP","oai"
AT+CGDCONT=2
AT+CGDCONT=3

# (Optional, debug only, AT commands) Activate PDP context, retrieve IP address and test with ping
AT+CGACT=1,1
AT+CGPADDR=1
AT+QPING=1,"openairinterface.org"
```

### 5.1.2 Ping test
- UE host
```bash
ping 192.168.70.135 -t -S 12.1.1.2
```
- CN5G host
```bash
docker exec -it oai-ext-dn ping 12.1.1.2
```

### 5.1.3 Downlink iPerf test
- UE host
    - Download iPerf for Microsoft Windows from [here](https://iperf.fr/download/windows/iperf-2.0.9-win64.zip).
    - Extract to Desktop and run with Command Prompt:
```bash
cd C:\Users\User\Desktop\iPerf\iperf-2.0.9-win64\iperf-2.0.9-win64
iperf -s -u -i 1 -B 12.1.1.2
```

- CN5G host
```bash
docker exec -it oai-ext-dn iperf -u -t 86400 -i 1 -fk -B 192.168.70.135 -b 100M -c 12.1.1.2
```

# 6. Advanced configurations (optional)

## 6.1 USRP N300 and X300 Ethernet Tuning

Please also refer to the official [USRP Host Performance Tuning Tips and Tricks](https://kb.ettus.com/USRP_Host_Performance_Tuning_Tips_and_Tricks) tuning guide.

The following steps are recommended. Please change the network interface(s) as required. Also, you should have 10Gbps interface(s): if you use two cables, you should have the XG interface. Refer to the [N300 Getting Started Guide](https://kb.ettus.com/USRP_N300/N310/N320/N321_Getting_Started_Guide) for more information.

* Use an MTU of 9000: how to change this depends on the network management tool. In the case of Network Manager, this can be done from the GUI.
* Increase the kernel socket buffer (also done by the USRP driver in OAI)
* Increase Ethernet Ring Buffers: `sudo ethtool -G <ifname> rx 4096 tx 4096`
* Disable hyper-threading in the BIOS (This step is optional)
* Optional: Disable KPTI Protections for Spectre/Meltdown for more performance. **This is a security risk.** Add `mitigations=off nosmt` in your grub config and update grub. (This step is optional)

Example code to run:
```
for ((i=0;i<$(nproc);i++)); do sudo cpufreq-set -c $i -r -g performance; done
sudo sysctl -w net.core.wmem_max=62500000
sudo sysctl -w net.core.rmem_max=62500000
sudo sysctl -w net.core.wmem_default=62500000
sudo sysctl -w net.core.rmem_default=62500000
sudo ethtool -G enp1s0f0 tx 4096 rx 4096
```

## 6.2 Real-time performance workarounds
- Enable Performance Mode `sudo cpupower idle-set -D 0`
- If you get real-time problems on heavy UL traffic, reduce the maximum UL MCS using an additional command-line switch: `--MACRLCs.[0].ul_max_mcs 14`.
- You can also reduce the number of LDPC decoder iterations, which will make the LDPC decoder take less time: `--L1s.[0].max_ldpc_iterations 4`.

## 6.3 Uplink issues related with noise on the DC carriers
- There is noise on the DC carriers on N300 and especially the X300 in UL. To avoid their use or shift them away from the center to use more UL spectrum, use the `--tune-offset <Hz>` command line switch, where `<Hz>` is ideally half the bandwidth, or possibly less.

## 6.4 Lower latency on user plane
- To lower latency on the user plane, you can force the UE to be scheduled constantly in uplink: `--MACRLCs.[0].ulsch_max_frame_inactivity 0` .
