Lab 3: TDD Reconfiguration rApp

In this lab, you will deploy a 5G Standalone (SA) network using the OpenAirInterface (OAI) RF Simulator for the gNB and the OAI minimal 5G Core (5GC).

In the second phase of the experiment, you will use the BubbleRAN rApp SDK and its oam_services to dynamically reconfigure the TDD pattern of the RAN cell. The configuration is applied through the Non-RT RIC and SMO, and the gNB is automatically restarted to apply the changes. This simulates OAM-based control of the access network using an rApp.

open-ran.yaml

apiVersion: athena.trirematics.io/v1
kind: Network
metadata:
    name: oran
    namespace: trirematics
spec:
    slices:
        - plmn: "00101"
          dnn: internet
          network-mode: IPv4
          service-type: 1
          differentiator: 0x000001 
          ipv4-range: "12.1.1.0/24"
          ipv6-range: "2001:1:2::/64"
    access:
        - name: oai-gnb
          stack: 5g-sa
          model: oai-ran/monolithic-gnb
          radio:
              device: rf-sim
          identity:
              an-id: 10
              tracking-area: 1
          cells:
              - band: n78
                arfcn: 641280
                bandwidth: 40MHz
                subcarrier-spacing: 30kHz
                tdd-config:
                    period: 5ms
                    dl-slots: 7
                    dl-symbols: 6
                    ul-slots: 2
                    ul-symbols: 4
          core-networks:
              - oai-5gc.oran
          controller: ric.oran
    core:
        - name: oai-5gc
          stack: 5g-sa
          model: oai-cn/minimal
          identity:
              region: 0
              cn-group: 4
              cn-id: 5
    edge:
        - name: ric
          stack: 5g-sa
          model: mosaic5g/flexric
        - name: sdl
          stack: 5g-sa
          model: mosaic5g/xapps-sdl
    dns:
        ipv4:
            default: 8.8.8.8
            secondary: 8.8.4.4
---
apiVersion: athena.trirematics.io/v1
kind: Terminal
metadata:
    name: ue1
    namespace: trirematics
spec:
    vendor: oai
    stack: 5g-sa
    model: terminal/nr-rfsim
    preferred-access: oai-gnb.oran
    target-cores:
        - oai-5gc.oran
    identity:
        imsi: "001010000000001"
        pin: "1234"
        opc: "0xc42449363bbad02b66d16bc975d77cc1"
        key: "0xfec86ba6eb707ed08905757b1bb44b8f"
        sqn: "0xff9bb4000001"
    slice:
        dnn: internet
        network-mode: IPv4
        service-type: 1
        differentiator: 0x000001
    radio:
        bands:
            - n78
    readiness-check:
        method: ping
        target: google-ip
        interface-name: oaitun_ue0

Network Deployment

Deploy the file using the command brc install network open-ran.yaml.

The network includes a single access network node with one cell. Initially, the TDD configuration is:

period: "5ms"
dl_slots: 7
dl_symbols: 6
ul_slots: 2
ul_symbols: 4

Check for the status of the deployment using the command brc observe and make sure all the Elements are in the 1/1 Y state.

Please run the following command to check the UE connectivity before updating the TDD configuration:

brc test rtt ue1 gateway -- -c 3

TDD Pattern Change via rApp

tdd-rapp.py

from br_rapp_sdk import OAMServices
from br_rapp_sdk.oam_services.network_types import *

if __name__ == "__main__":

    # Initialize the OAMServices client
    oam_services = OAMServices()

    # Get the list of networks
    net_id = NetworkId("oran")
    result = oam_services.network.get_network(network_id=net_id)
    if result.status == "success":
        net_spec = result.data.get("item", [])
    else:
        print("Failed to retrieve networks: ", result.error)
        exit(1)
        
    # Print the current TDD configuration
    print("TDD Config before change:", net_spec.access[0].cells[0].tdd_config)

    # Change the TDD configuration
    new_tdd_config = TDDConfig(
        period="5ms",
        dl_slots=6,
        dl_symbols=6,
        ul_slots=3,
        ul_symbols=4
    )
    net_spec.access[0].cells[0].tdd_config = new_tdd_config

    # Apply the updated network specification
    result = oam_services.network.apply_network(
        network_name=net_id,
        network_spec=net_spec
    )
    if result.status == 'success':
        network_id = result.data.get('network_id')
        print(f"Access applied successfully: {network_id}")
    else:
        print(f"Error applying access: {result.error}")
    
    # Retrieve the updated network to verify the change
    result = oam_services.network.get_network(network_id=net_id)
    if result.status == "success":
        updated_net_spec = result.data.get('item')
        print("TDD Config after change:", updated_net_spec.access[0].cells[0].tdd_config)
    else:
        print("Failed to retrieve updated network: ", result.error)

You will change this configuration to via tdd-rapp.py:

period: "5ms"
dl_slots: 6
dl_symbols: 6
ul_slots: 3
ul_symbols: 4

Use the following commands to run the rApp within the cluster:

python3 ./tdd-rapp.py

danger

Make sure the BubbleRAN rApp SDK is installed in your environment. You can install it using the command pip3 install br-rapp-sdk.

danger

Run the rApp inside the cluster, and make sure your kubeconfig file is located at ~/.kube/config.

After running the rApp, the RAN will be restarted to apply the new TDD configuration. You can check the status of the deployment using the command brc observe, and make sure all the Elements are in the 1/1 Y state. Please run the following command to check the UE connectivity after updating the TDD configuration:

brc test rtt ue1 gateway -- -c 3

💬 Questions

1. Does this rApp need an xApp to function?
2. What is the role of the TDD pattern in the context of 5G networks? Hint: https://bubbleran.com/docs/user-guide/studio/lessons/tdd
3. How the TDD pattern change can impact the network performance and user experience?
4. Use OAM services to change the bandwidth and frequency of the gNB.