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Configuration

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Ali Güngör edited this page Jan 29, 2021 · 50 revisions

Overview

Configuration is the most important part, and almost all of the problems are caused by an incorrect configuration.

nr-ue accepts a UE configuration file as a parameter, and nr-gnb accepts a gNB configuration file as a parameter. The syntax is the following:

nr-ue -c myconfig1.yaml
nr-gnb -c myconfig2.yaml

We also provide some example configuration files located at config folder. You can either edit them, or write your own files. But do not try to use example configurations as is without setting parameters for your own environment.

An example command line for using sample configurations:

cd ~/UERANSIM/build

./nr-gnb -c ../config/open5gs-gnb.yaml
./nr-ue -c ../config/open5gs-ue.yaml

UE Configuration

  • supi: IMSI number of the UE must be written in this field. Note that we only support IMSI as a SUPI, i.e NAI is not supported.
  • mcc: Mobile Country Code value for this UE. This value must be consistent with SUPI.
  • mnc: Mobile Network Code value for this UE. This value must be consistent with SUPI. MNC value can be either 2 digits or 3 digits. Note that 2-digit values are semantically different from 3-digit values. e.g 25 is different from 025. More details can be found on TS 23.501
  • key: This is the permanent subscription key assigned for this specific UE.
  • op: Operator code value (in either OP or OPC) must be written here. You should set opType as OP if you write an OP value here, and you should set opType as OPC if you write an OPC value here. You can either use OP or OPC keys.
  • amf: Authentication Management Field (AMF) must be written here. Note that this is a different thing from core network function AMF (Access and Mobility Management Function)
  • imei: IMEI number of the device. IMEI is used if no SUPI provided and for emergency registration etc. This value is generally not used. And this is the only field that is not much important. All other fields must be set precisely.
  • gnbSearchList: This is the list of IP addresses of gNB for radio link simulation. You can write multiple IP addresses for multiple gNBs. UE will try to pick some gNB from this list. The IP address must match with linkIp parameter in the gNB config file. Otherwise UE cannot connect to the gNB. By default we wrote 127.0.0.1 in the sample configuration files, but change this and linkIp parameter according to your environment if you use UE and gNB in different machines.
  • sessions: This is the list of initial PDU sessions. These sessions are automatically established after the UE successfully registers to the 5G core network. You can add multiple PDU sessions to this list. (No more than 15). If you don't want an initial PDU session, you can completely delete the sessions parameter. Sessions has type, apn and slice parameters. Only IPv4 is supported for now as a PDU session type. apn field specifies the Access Point Name. slice parameter is optional and specifies the S-NSSAI for this specific PDU session. Also sd parameter is optional as well, but sst is always required if the slice parameter is included. You can delete optional parameters or set null to the relevant fields.
  • slices: List of requested NSSAIs by this UE. This field is explained above, except this time slices parameter itself is not optional. (sd is still optional but sst is required.)
  • integrity/ciphering: Here you can set supported integrity and ciphering algorithm for this specific UE. Normally UERANSIM supports all of the algorithms but you can disable some of them manually by this configuration.

gNB Configuration

  • mcc/mnc: This fields are already explained above.
  • nci: This field specifies the NR Cell Identity. Also idLength specifies the bit length of the gNB ID which is a part of this NR Cell Identity. More on TS 38.413
  • tac: Tracking Area Code (TAC) value for this cell.
  • linkIp: Local IP for radio link simulation for this gNB. UE should connect to this IP address for radio simulation. The IP address must match with gnbSearchList parameter in the UE config file. Otherwise UE cannot connect to the gNB. By default we wrote 127.0.0.1 in the sample configuration files, but change this and gnbSearchList parameter according to your environment if you use UE and gNB in different machines.
  • ngapIp: Local IP for N2 interface for this gNB. AMF will send SCTP packets to this IP address, therefore set this IP precisely. Otherwise AMF cannot connect to the gNB and SCTP timeout error occurs. By default we wrote 127.0.0.1 in the sample configuration files, but change this according to your environment if you use gNB and AMF in different machines. (Also our suggestion is always using UERANSIM and core network in different machines.)
  • gtpIp: Local IP for N3 interface for this gNB. UPF will send GTP packets to this IP address, therefore set this IP precisely. Otherwise UPF cannot send datagrams to the gNB and data plane functions cannot work. By default we wrote 127.0.0.1 in the sample configuration files, but change this according to your environment if you use gNB and UPF in different machines. (Also our suggestion is always using UERANSIM and core network in different machines.)
  • amfConfigs: List of AMF IP address and port information for N2 (NGAP) interface. This is the other endpoint of what you set in ngapIp address. This time you should set this value as AMF's IP address. By default we wrote 127.0.0.X in the sample configuration files, but change this according to your environment if you use gNB and AMF in different machines. This value is normally a list, but currently only first specified AMF is used. More complex AMF selection mechanism will be implemented in the future.
  • slices: This field is explained in the UE configurations. And it is the supported list of slices by the gNB.
  • ignoreStreamIds: Some core networks may not handle SCTP stream numbers properly. Set this field to true if you want to ignore such errors. If you are using open5gs or free5gc, you should set this value to true.

Environment

  • Make sure that all of the nodes in your setup (UE, gNB, and core network) can connect to each other over the network, and some firewall rule does not block the 5G traffic between nodes.
  • SCTP protocol with default port number 38412 is used between gNB and AMF. UDP protocol with assigned port number 2152 is used between gNB and UPF. UDP based another protocol with assigned port number 4997 is used between gNB and UE.

Next Steps:

Usage

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