gnbsim is a 5G SA gNB/UE (Rel. 16) simulator for testing 5G System. The project is aimed to understand 5GC more efficiently than just reading 3GPP standard documents.

• Golang environment on a Linux server to run gnbsim.

  • The project is tested on Raspbian GNU/Linux 10 (buster)

• free5gc is running somewhere.

  • free5gc/free5gc v3.0.5 is used for testing the project.
  • Tested subscriber(s) have been provisioned by the free5gc web console.
  • change the free5gc configurations.

    • free5gc/config/amfcfg.conf

      ngapIpList:
        - 192.168.1.17        # external IP address for N2 address.
        # - 127.0.0.1
      

    • free5gc/config/smfcfg.conf

      interfaces:
        - interfaceType:
          endpoints:
            - 192.168.1.18 # external IP address for GTP-U (N3) address.
            # - 127.0.0.8
      

    • free5gc/src/upf/build/config/upfcfg.yaml

      gtpu:
        - addr: 192.168.1.18  # external IP address for GTP-U (N3) address.
        # - addr: 127.0.0.8
      

• Download the related files.

  $ git clone https://github.com/hhorai/gnbsim.git
  $ cd gnbsim
  

• Build the example binary.

  $ make test		# (optional) unit test for each libary.
  $ make
  

• Edit the configuration file (example.json).

  • SUPI(IMSI) is formed by mcc + mnc + msin. (e.g. 208930123456789)
  • NGAPPeerAddr indicates the IP address for N2 used by the AMF side.
  • GTPuIFname indicates the interface name for GTP-U used by gnbsim.
  • GTPuLocalAddr indicates the IP address for GTP-U used by gnbsim.
  • url indicates the destined URL for testing U-plane directly accessed by UEs.
  • wiki page might be helpful to understand the environment.

  $ cd example
  $ vi example.json
  

• Run gnbsim

  • root privilege is required to set an IP address which is dynamically assigned by the SMF.

  $ sudo ./example
  

  • Then you can find the following line in the debug message. In this case, your configuration for OPc and K are both correct.

  ***** Integrity check passed
  

  • And you could also find your UEs in 'subscriber' page in the free5gc web console.