本文整理自我 2023 年在 HackMD 上的實作筆記，指令與版本以當時環境為準（Ubuntu 22.04、srsRAN 4G / Project、Open5GS）。

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1. System Requirements

要跑起 srsRAN Project 的 gNB，需要：

  • 一台 Linux PC（Ubuntu 20.04 以上；本文用 22.04）
  • 一台 USRP（B210 或 X310），或改用 ZMQ 在同一台機器上模擬射頻
  • srsRAN Project（gNB）
  • 第三方 5G core：本文用 Open5GS
  • 第三方 5G UE：本文用 srsRAN 4G 的 srsUE 經 ZMQ 連接

2. UHD

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From: https://files.ettus.com/manual/page_build_guide.html

2-1 Setting up the dependencies on Ubuntu

sudo apt-get install 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

2-2 Getting the source code

git clone https://github.com/EttusResearch/uhd.git

2-3 Build Instructions

cd <uhd-repo-path>/host
mkdir build
cd build
cmake ../
make
make test # This step is optional
sudo make install

3. ZMQ

3-1 Install development libraries

sudo apt-get install cmake make gcc g++ pkg-config libfftw3-dev libmbedtls-dev libsctp-dev libyaml-cpp-dev libgtest-dev
sudo apt-get install libzmq3-dev

3-2 Install libzmq

git clone https://github.com/zeromq/libzmq.git
cd libzmq
./autogen.sh
./configure
make
sudo make install
sudo ldconfig

3-2 Install czmq

git clone https://github.com/zeromq/czmq.git
cd czmq
./autogen.sh
./configure
make
sudo make install
sudo ldconfig

4. srsRAN 4G

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From: https://docs.srsran.com/projects/4g/en/latest/index.html

4-1 Install required libraries

sudo apt-get install build-essential cmake libfftw3-dev libmbedtls-dev libboost-program-options-dev libconfig++-dev libsctp-dev

4-2 Download and build srsRAN 4G

git clone https://github.com/srsRAN/srsRAN_4G.git
cd srsRAN_4G
mkdir build
cd build
cmake ../
make
make test

4-3 Install srsRAN 4G

sudo make install
srsran_install_configs.sh user

5. srsRAN Project

截圖

From: https://docs.srsran.com/projects/project/en/latest/index.html

5-1 Install required libraries

sudo apt-get install cmake make gcc g++ pkg-config libfftw3-dev libmbedtls-dev libsctp-dev libyaml-cpp-dev libgtest-dev

5-2 RF driver 的選擇

srsRAN Project 支援的 RF 前端

gNB 可以接 USRP B210、X310，或用 ZMQ 不接任何硬體。USRP 需要先裝好第 2 節的 UHD；ZMQ 需要第 3 節的 libzmq 與 czmq。本文的 gNB 與 srsUE 在同一台機器上以 ZMQ 對接，實機測試時換成 B210。

5-3 Download and build srsRAN Project

不用 ZMQ 時：

git clone https://github.com/srsRAN/srsRAN_Project.git
cd srsRAN_Project
mkdir build
cd build
cmake ../
make -j $(nproc)
make test -j $(nproc)

要用 ZMQ 時，cmake 要多帶兩個旗標：

git clone https://github.com/srsran/srsRAN_Project.git
cd srsRAN_Project
mkdir build
cd build
cmake ../ -DENABLE_EXPORT=ON -DENABLE_ZEROMQ=ON
make -j`nproc`

make test 全數通過

5-4 Install srsRAN Project

sudo make install

6. Open5gs

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From: https://open5gs.org/open5gs/docs/guide/01-quickstart/

6-1 Getting MongoDB

sudo apt update
sudo apt install gnupg
curl -fsSL https://pgp.mongodb.com/server-6.0.asc | sudo gpg -o /usr/share/keyrings/mongodb-server-6.0.gpg --dearmor

6-1-2 On ubuntu 22.04 (Jammy)

echo "deb [ arch=amd64,arm64 signed-by=/usr/share/keyrings/mongodb-server-6.0.gpg] https://repo.mongodb.org/apt/ubuntu jammy/mongodb-org/6.0 multiverse" | sudo tee /etc/apt/sources.list.d/mongodb-org-6.0.list

6-1-3 Install the MongoDB packages

sudo apt update
sudo apt install -y mongodb-org
sudo systemctl start mongod (if '/usr/bin/mongod' is not running)
sudo systemctl enable mongod (ensure to automatically start it on system boot)

6-2 Install Open5GS

sudo add-apt-repository ppa:open5gs/latest
sudo apt update
sudo apt install open5gs

6-3 Install the WebUI of Open5GS

6-3-1 Download and import the Nodesource GPG key

sudo apt update
sudo apt install -y ca-certificates curl gnupg
sudo mkdir -p /etc/apt/keyrings
curl -fsSL https://deb.nodesource.com/gpgkey/nodesource-repo.gpg.key | sudo gpg --dearmor -o /etc/apt/keyrings/nodesource.gpg

6-3-2 Create deb repository

NODE_MAJOR=20
echo "deb [signed-by=/etc/apt/keyrings/nodesource.gpg] https://deb.nodesource.com/node_$NODE_MAJOR.x nodistro main" | sudo tee /etc/apt/sources.list.d/nodesource.list

6-3-3 Run Update and Install

sudo apt update
sudo apt install nodejs -y

6-3-3 Install WebUI of Open5GS

curl -fsSL https://open5gs.org/open5gs/assets/webui/install | sudo -E bash -

6-4 Register Subscriber Information

6-4-1 Connect to http://localhost:9999 and login with admin account.

Username : admin
Password : 1423

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6-4-2 To add subscriber information, you can do WebUI operations in the following order:

1. Go to Subscriber Menu.
2. Click + Button to add a new subscriber.
3. Fill the IMSI, security context(K, OPc, AMF), and APN of the subscriber.
4. Click SAVE Button

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6-5 Adding a route for the UE to have WAN connectivity

To enable forwarding and add the NAT rule, enter

### Enable IPv4/IPv6 Forwarding
sudo sysctl -w net.ipv4.ip_forward=1
sudo sysctl -w net.ipv6.conf.all.forwarding=1

### Add NAT Rule
sudo iptables -t nat -A POSTROUTING -s 10.45.0.0/16 ! -o ogstun -j MASQUERADE
sudo ip6tables -t nat -A POSTROUTING -s 2001:db8:cafe::/48 ! -o ogstun -j MASQUERADE

7. Modify setting file

7-0 系統架構

srsRAN Project gNB 與 Open5GS 的系統架構

gNB 的設定檔都在 srsRAN_Project/configs/，依你的 RF 前端挑一個當底，例如 B210 用 gnb_rf_b200_tdd_n78_20mhz.yml，ZMQ 用 gnb_zmq.yml：

cd srsRAN_Project/configs
ls

configs 目錄

7-1 Modify gnb.conf

cd srsRAN_Project/configs
sudo vim gnb_zmq.yml
amf:
  addr: 127.0.0.5                  
  bind_addr: 127.0.0.5

7-2 Modify amf.yml

cd /etc/open5gs
sudo vim amf.yaml
  guami:
    - plmn_id:
        mcc: 001
        mnc: 01
      amf_id:
        region: 2
        set: 1
  tai:
    - plmn_id:
        mcc: 001
        mnc: 01
      tac: 7
  plmn_support:
    - plmn_id:
        mcc: 001
        mnc: 01

7-3 Modify nrf.yml

sudo vim nrf.yaml
nrf:
  serving:  # 5G roaming requires PLMN in NRF
    - plmn_id:
        mcc: 001
        mnc: 01

8. Turn on open5gs / gNB / UE

8-1 Turn on/off open5gs

## turn on 
sudo systemctl restart open5gs-amfd
or
sudo systemctl restart open5gs-*

## turn off
sudo systemctl stop open5gs-amfd
or
sudo systemctl restart open5gs-*

8-2 Turn on gNB

sudo gnb -c gnb_rf_b200_tdd_n78_10mhz.yml

8-3 Turn on UE

=> If UE, gNB, CN in one VM do network namespace

sudo ip netns add ue1
sudo ip netns list
sudo ip netns exec ue1 ping 172.16.0.1

Turn on UE

sudo srsue ue.conf

9. Adding a route for the UE to have WAN connectivity

=> In order to bridge between the PGWU/UPF and WAN (Internet), must enable IP forwarding and add a NAT rule to your IP Tables.

9-1 To enable forwarding and add the NAT rule

### Enable IPv4/IPv6 Forwarding
sudo sysctl -w net.ipv4.ip_forward=1
sudo sysctl -w net.ipv6.conf.all.forwarding=1

### Add NAT Rule
sudo iptables -t nat -A POSTROUTING -s 10.45.0.0/16 ! -o ogstun -j MASQUERADE
sudo ip6tables -t nat -A POSTROUTING -s 2001:db8:cafe::/48 ! -o ogstun -j MASQUERADE

9-2 Configure the firewall correctly

sudo ufw status
=> Status: active
sudo ufw disable
=> Firewall stopped and disabled on system startup
sudo ufw status
=> Status: inactive

9-3 add a default route for the UE

sudo ip netns exec ue1 ip route add default via 10.45.0.1 dev tun_srsue

Routing table of ue1:

user@user:~$ sudo ip netns exec ue1 route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         10.45.0.1       0.0.0.0         UG    0      0        0 tun_srsue
10.45.0.0       0.0.0.0         255.255.255.0   U     0      0        0 tun_srsue

10. Application

10-1 Using chrome to browse website with srsue

Download chrome

wget -c https://dl.google.com/linux/direct/google-chrome-stable_current_amd64.deb
sudo dpkg -i google-chrome-stable_current_amd64.deb
sudo apt-get install -f
sudo ip netns exec ue1 su -c "DISPLAY=:0 google-chrome --no-sandbox" $USER

10-2 Using tun_srsue to ping

sudo ping -I tun_srsue google.com
sudo traceroute -i tun_srsue google.com

********************* Troubleshooting *********************

Can not connect to network:

sudo vim /etc/resolv.conf
nameserver 8.8.8.8

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