telneto1.md

[[TOC]]

The telnet O1 module (telnetsrv_o1.c) can be used to perform some O1-related actions (reading data, starting and stopping the nr-softmodem, reconfigurating frequency and bandwidth).

General usage

The usage is similar to the general telnet usage, but in short:

./build_oai --ninja -c --gNB --nrUE --build-lib telnetsrv

to build everything including the telnet library. Then, run the nr-softmodem by activating telnet and loading the o1 module:

./nr-softmodem -O <config> --telnetsrv --telnetsrv.shrmod o1

Afterwards, it should be possible to connect via telnet on localhost, port 9090. Use help to get help on the different command sections, and type e.g. o1 stats to get statistics (more information further below):

$ telnet 127.0.0.1 9090
Trying 127.0.0.1...
Connected to 127.0.0.1.
Escape character is '^]'.

softmodem_gnb> help
[...]
   module 4 = o1:
      o1 stats
      o1 config ?
      o1 stop_modem
      o1 start_modem
[...]
softmodem_gnb> o1 stats
[...]
softmodem_gnb> exit
Connection closed by foreign host.

It also possible to send a command "directly from the command line", by piping the command into netcat:

echo o1 stats | nc -N 127.0.0.1 9090

Note that only one telnet client can be connected at a time.

Get statistics

Use the o1 stats command. The output is in JSON format:

{
  "o1-config": {
    "BWP": {
      "dl": [
        {
          "bwp3gpp:isInitialBwp": true,
          "bwp3gpp:numberOfRBs": 106,
          "bwp3gpp:startRB": 0,
          "bwp3gpp:subCarrierSpacing": 30
        }
      ],
      "ul": [
        {
          "bwp3gpp:isInitialBwp": true,
          "bwp3gpp:numberOfRBs": 106,
          "bwp3gpp:startRB": 0,
          "bwp3gpp:subCarrierSpacing": 30
        }
      ]
    },
    "NRCELLDU": {
      "nrcelldu3gpp:ssbFrequency": 641280,
      "nrcelldu3gpp:arfcnDL": 640008,
      "nrcelldu3gpp:bSChannelBwDL": 40,
      "nrcelldu3gpp:arfcnUL": 640008,
      "nrcelldu3gpp:bSChannelBwUL": 40,
      "nrcelldu3gpp:nRPCI": 0,
      "nrcelldu3gpp:nRTAC": 1,
      "nrcelldu3gpp:mcc": "208",
      "nrcelldu3gpp:mnc": "95",
      "nrcelldu3gpp:sd": 16777215,
      "nrcelldu3gpp:sst": 1
    },
    "device": {
      "gnbId": 1,
      "gnbName": "gNB-Eurecom-5GNRBox",
      "vendor": "OpenAirInterface"
    }
  },
  "O1-Operational": {
    "frame-type": "tdd",
    "band-number": 78,
    "num-ues": 1,
    "ues": [
      6876
    ],
    "load": 9,
    "ues-thp": [
      {
        "rnti": 6876,
        "dl": 3279,
        "ul": 2725
      }
    ]
  }
}

Note that no actual JSON engine is used, so no actual verification is done; it is for convenience of the consumer. To verify, you can employ jq:

echo o1 stats | nc -N 127.0.0.1 9090 | awk '/^{$/, /^}$/' | jq .

(awk's pattern matching makes that only everything between the first { and its corresponding } is printed).

There are two sections:

1. .o1-config show some stats that map directly to the O1 Netconf model. Note that only one MCC/MNC/SD/SST (each) are supported right now. Also, note that as per 3GPP specifications, SD of value 0xffffff (16777215 in decimal) means "no SD". bSChannelBwDL/UL is reported in MHz.
2. .O1-operational output some statistics that do not map yet to any netconf parameters, but that might be useful nevertheless for a consumer.

Write a new configuration

Use o1 config to write a configuration:

echo o1 config nrcelldu3gpp:ssbFrequency 620736 nrcelldu3gpp:arfcnDL 620020 nrcelldu3gpp:bSChannelBwDL 51 bwp3gpp:numberOfRBs 51 bwp3gpp:startRB 0 | nc -N 127.0.0.1 9090

You have to pass the above parameters in exactly this order. The softmodem needs to be stopped; it will pick up the new configuration when starting the softmodem again.

Note that you cannot switch three-quarter sampling for this as of now.

For values of the configuration, refer to the next section.

Use hardcoded configuration

Use o1 bwconfig to write a hard-coded configuration for 20 or 40 MHz cells:

echo o1 bwconfig 20 | nc -N 127.0.0.1 9090
echo o1 bwconfig 40 | nc -N 127.0.0.1 9090

The softmodem needs to be stopped; it will pick up the new configuration when starting the softmodem again.

Use o1 stats to see which configurations are set by these commands for the parameters nrcelldu3gpp:ssbFrequency, nrcelldu3gpp:arfcnDL, nrcelldu3gpp:arfcnUL, nrcelldu3gpp:bSChannelBwDL, nrcelldu3gpp:bSChannelBwUL, and bwp3gpp:numberOfRBsbwp3gpp:startRB. Furthermore, for 20MHz, it disables three-quarter sampling, whereas it enables three-quarter sampling for 40MHz.

Restart the softmodem

Use o1 stop_modem to stop the nr-softmodem. To restart the softmodem, use o1 start_modem:

echo o1 stop_modem | nc -N 127.0.0.1 9090
echo o1 start_modem | nc -N 127.0.0.1 9090

In fact, stopping terminates all L1 threads. It will be as if the softmodem "freezes", and no periodical output of statistics will occur (the O1 telnet interface will still work, though). Starting again will "defreeze" the softmodem.

Upon restart, the DU sends a gNB-DU configuration update to the CU to inform it about the updated configuration. Therefore, this also works in F1.