RSRP Reporting for multi cell setup (Issue with E2 KPM Style 3)

[Keilwerth11270]

Hi all,

I need to subscribe to RSRP metrics for two cells. I have attached my gNB config file in a zip folder attached at the end of this post.

As far as I know, E2 KPM Style 3 allows for per cell metric reporting. I am attempting to subscribe to RSRP metrics using this function:

    @xAppBase.start_function
    def start(self, e2_node_id, metric_names):
        try:
            print("\n=== Starting Cell RSRP Monitor xApp ===")
    
            matching_conds = [
                {
                    'matchingCondChoice': ('testCondInfo', {
                        'testType': ('ul-rSRP', 'true'),
                        'testExpr': 'lessthan',
                        'testValue': ('valueInt', 1000)
                    })
                },
                {
                    'matchingCondChoice': ('measLabel', {
                        'noLabel': 'true',
                        'sliceID': {'sST': bytes.fromhex('08')},
                        'fiveQI': 64,
                        'qCI': 9
                    })
                }
            ]

# I came to the conclusion of using these values based on the output of the PCAPs 

            # Configure monitoring parameters 
            report_period = 2000
            granul_period = 999
            
            print(f"\nSubscription Configuration:")
            print(f"E2 Node ID: {e2_node_id}")
            print(f"Metrics: {metric_names}")
            print(f"Report Period: {report_period} ms")
            print(f"Granularity Period: {granul_period} ms")
            print(f"Matching Conditions: {matching_conds}")
            
            self.e2sm_kpm.subscribe_report_service_style_3(
                e2_node_id,
                report_period,
                matching_conds,
                metric_names[0],
                granul_period,
                self.my_subscription_callback
            )
            
            print("\nINFO: Successfully subscribed to RSRP measurements")
                
        except Exception as e:
            print(f"\nCRITICAL: Failed to start xApp")
            print(f"ERROR Details: {str(e)}")
            print(traceback.format_exc())
            raise

The output of my xApp (code also available in the zip file) is as follows:

=== Command Line Arguments ===
{
  "config": "",
  "http_server_port": 8091,
  "rmr_port": 4561,
  "e2_node_id": "gnb_001_001_0000019b",
  "ran_func_id": 2
}
1733711404520 7/RMR [INFO] ric message routing library on SI95 p=4561 mv=3 flg=00 id=a (f447e29 4.9.4 built: Dec 13 2023)

INFO: Initializing Cell Monitor xApp
INFO: Cell metrics tracking initialized

=== Starting Cell RSRP Monitor xApp ===

Subscription Configuration:
E2 Node ID: gnb_001_001_0000019b
Metrics: ['RSRP']
Report Period: 2000 ms
Granularity Period: 999 ms
Matching Conditions: [{'matchingCondChoice': ('testCondInfo', {'testType': ('ul-rSRP', 'true'), 'testExpr': 'lessthan', 'testValue': ('valueInt', 1000)})}, {'matchingCondChoice': ('measLabel', {'noLabel': 'true', 'sliceID': {'sST': b'\x08'}, 'fiveQI': 64, 'qCI': 9})}]
Successfully subscribed with Subscription ID:  2pxcwUMtiPRRQevT0hEGUE3xRUo

INFO: Successfully subscribed to RSRP measurements
Received Subscription ID to E2EventInstanceId mapping: 2pxcwUMtiPRRQevT0hEGUE3xRUo -> 1
{'response': 'OK', 'status': 200, 'payload': '{}', 'ctype': 'application/json', 'attachment': None, 'mode': 'plain'}
10.0.2.13 - - [09/Dec/2024 02:30:05] "POST /ric/v1/subscriptions/response HTTP/1.1" 200 -

After that, nothing else would print (where the RSRP metrics should have been printing), so I checked the RIC for any messages but saw that there were no errors:

ric_submgr          | RMR is ready now ...
ric_rtmgr_sim       | 2024/12/09 02:29:47 POST /ric/v1/handles/associate-ran-to-e2t  body: [{"E2TAddress":"10.0.2.10:38000","ranNamelist":["gnb_001_001_0000019b"]}] elapsed: 17.528µs
ric_rtmgr_sim       | 2024/12/09 02:29:47 POST /ric/v1/handles/associate-ran-to-e2t  body: [{"E2TAddress":"10.0.2.10:38000","ranNamelist":["gnb_001_001_0000019b"]}] elapsed: 6.503µs
ric_rtmgr_sim       | 2024/12/09 02:30:05 POST /ric/v1/handles/xapp-subscription-handle  body: {"address":"10.0.2.20","port":4561,"subscription_id":1} elapsed: 11.124µs

Which led me to think there were issues elsewhere.

There are errors in the E2 PCAP file. I have been struggling with getting the E2 message right for a while now, I am not sure any more how to fix my matching_conds to fulfill what the E2 interface wants of me... any help is appreciated, please let me know if more information is needed.

Here I have attached a zip file containing my NGAP/E2AP PCAPs, gNB config file, and xApp python file.

[pgawlowicz]

The matching conditions in Report Style 3 are not supported on the srsRAN side. Also, filtering measurements by cell ID is not implemented.

[pgawlowicz]

you have to update your config as there were some changes.

[Keilwerth11270]

you have to update your config as there were some changes.

Is there any documentation for how to set up handover for the latest release?

Here is where I am at now:

gnb_id: 411
gnb_id_bit_length: 32

ru_sdr:
  device_driver: uhd
  device_args: type=x300
  srate: 30.72
  lo_offset: 30.72
  clock: internal
  sync: internal
  tx_gain: 15
  rx_gain: 15

cell_cfg:
  dl_arfcn: 640000
  band: 78
  channel_bandwidth_MHz: 20
  common_scs: 30
  plmn: "00101"
  tac: 7
  nof_antennas_dl: 1
  nof_antennas_ul: 1

cells:
  - pci: 1
    prach:
      prach_root_sequence_index: 0
  - pci: 2
    prach:
      prach_root_sequence_index: 64

cu_cp:
  amf:
    addr: 127.0.0.5
    bind_addr: 127.0.0.1
  mobility:
    trigger_handover_from_measurements: true
    cells:
      - nr_cell_id: 0x19B0
        periodic_report_cfg_id: 1
        ncells:
          - nr_cell_id: 0x19B1
            report_configs: [ 1, 2 ]
      - nr_cell_id: 0x19B1
        periodic_report_cfg_id: 1
        ncells:
          - nr_cell_id: 0x19B0
            report_configs: [ 1, 2 ]
    report_configs:
      - report_cfg_id: 1
        report_type: periodical
        report_interval_ms: 480
      - report_cfg_id: 2
        report_type: event_triggered
        event_triggered_report_type: a3
        a3_offset_db: 3
        a3_hysteresis_db: 0
        a3_time_to_trigger_ms: 100

metrics:
  enable_json_metrics: true
  addr: 38.68.232.68
  port: 55555

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

pcap:
  mac_enable: true
  mac_filename: /tmp/gnb_mac.pcap
  ngap_enable: true
  ngap_filename: /tmp/gnb_ngap.pcap
  e2ap_du_filename: /tmp/du_e2ap.pcap
  e2ap_enable: true

e2:
  enable_du_e2: true
  addr: 10.0.2.10
  port: 36421
  bind_addr: 0.0.0.0
  e2sm_kpm_enabled: true

The issue has to do with these three configurations as of now:

        a3_offset_db: 3
        a3_hysteresis_db: 0
        a3_time_to_trigger_ms: 100

Commenting out all three of those configurations results in this:

--== srsRAN gNB (commit e5d5b44b9) ==--

Invalid event A3/A6 measurement report configuration.
srsRAN ERROR: Invalid configuration detected.

I am changing the names in different ways by removing a3_ but there should be some documentation available. The current handover_x310.yml found at this link is not updated to the latest version.

When I try to run it to test, I get the same issue:

--== srsRAN gNB (commit e5d5b44b9) ==--

INI was not able to parse a3_report_type
Run with --help for more information.

The configuration reference is also not updated. I was also unable to find much commentary on the latest release of srsRAN for handover configurations. Any guidance on fixing the configuration would be greatly appreciated.

[pgawlowicz]

@brendan-mcauliffe could you check?

[Keilwerth11270]

Any update on this?

[pgawlowicz]

check the new config parameters here https://github.com/srsran/srsRAN_Project/blob/main/apps/units/o_cu_cp/cu_cp/cu_cp_unit_config_cli11_schema.cpp#L168