Issue Triggering Handover Between Two gNBs (5G SA with B210) Using tx_gain Command

[vlsmcin]

Hello everyone,

I'm trying to test the handover trigger between two gNBs in 5G SA mode.
My setup uses two USRP B210/N310 devices, both gNBs are successfully connected to the AMF.
When I disable airplane mode on the phone, it connects to 5G and has data connectivity, so the base setup is working.

To trigger the handover, I tried reducing the tx_gain to a low value (as per the documentation below):
srsRAN gNB Handover

I'm using the same gNB config for both nodes, except for the bind_addr, which is 172.22.0.1 on gNB1 and 172.22.0.100 on gNB2, both bridges are correctly configured and each gNB can communicate with the AMF:

# transmitting in band 78, with 20 MHz bandwidth and 30 kHz sub-carrier-spacing. A USRP B200 is configured
# as the RF frontend using split 8. Note in this example an external clock source is not used, so the sync
# is not defined and the default is used.

cu_cp:
  amf:
    addr: 172.22.0.10
    port: 38412
    bind_addr: 172.22.0.1
    supported_tracking_areas:
      - tac: 1
        plmn_list:
          - plmn: "00101"
            tai_slice_support_list:
              - sst: 1

ru_sdr:
  device_driver: uhd
  device_args: type=b200,num_recv_frames=64,num_send_frames=64
  srate: 23.04
  otw_format: sc12
  tx_gain: 80
  rx_gain: 40

cell_cfg:
  dl_arfcn: 632628
  band: 78
  channel_bandwidth_MHz: 20
  common_scs: 30
  plmn: "00101"
  tac: 1
  pci: 1

log:
  filename: /tmp/gnb.log
  all_level: warning

pcap:
  mac_enable: false
  mac_filename: /tmp/gnb_mac.pcap
  ngap_enable: false
  ngap_filename: /tmp/gnb_ngap.pcap

However, when I run the command:
tx_gain 0 10
I get the following error

Questions:

• What is the cause of this error?
• Is this a known issue in a specific version?
• If this is a old feature, there is a new feature with similar function?
• There is another way of triggering a handover based on signal intensity?