Missed incoming User-Plane PRACH messages

[ehitimum]

Issue Description

After the 2024-03-12T05:36:04.692031 [GNB ] [I] Radio Unit started successfully, I started getting these error untill I stop my gnb.

2024-03-12T05:36:04.706010 [OFH     ] [W] Missed incoming User-Plane PRACH messages for slot '477.17' and sector#0
2024-03-12T05:36:04.707012 [OFH     ] [W] Missed incoming User-Plane PRACH messages for slot '477.19' and sector#0
2024-03-12T05:36:04.711014 [OFH     ] [W] Missed incoming User-Plane PRACH messages for slot '478.7' and sector#0
2024-03-12T05:36:04.712014 [OFH     ] [W] Missed incoming User-Plane PRACH messages for slot '478.9' and sector#0
2024-03-12T05:36:04.716017 [OFH     ] [W] Missed incoming User-Plane PRACH messages for slot '478.17' and sector#0
2024-03-12T05:36:04.717008 [OFH     ] [W] Missed incoming User-Plane PRACH messages for slot '478.19' and sector#0
2024-03-12T05:36:04.721015 [OFH     ] [W] Missed incoming User-Plane PRACH messages for slot '479.7' and sector#0
2024-03-12T05:36:04.722011 [OFH     ] [W] Missed incoming User-Plane PRACH messages for slot '479.9' and sector#0
2024-03-12T05:36:04.726011 [OFH     ] [W] Missed incoming User-Plane PRACH messages for slot '479.17' and sector#0
2024-03-12T05:36:04.727013 [OFH     ] [W] Missed incoming User-Plane PRACH messages for slot '479.19' and sector#0
2024-03-12T05:36:04.731020 [OFH     ] [W] Missed incoming User-Plane PRACH messages for slot '480.7' and sector#0
2024-03-12T05:36:04.732009 [OFH     ] [W] Missed incoming User-Plane PRACH messages for slot '480.9' and sector#0
2024-03-12T05:36:04.736008 [OFH     ] [W] Missed incoming User-Plane PRACH messages for slot '480.17' and sector#0

Setup Details

This is my complete log file, test-gnb.log and this another log where I captured the log with much detail: gnb1.zip (please uzip before reading it.) I have a grand master that is connected with cu/du machine and ru machine with a front haul switch. I have tried many different prach configuration. Currently prach configuration index is 165.

This is the gnb configuration file,

amf:
  addr: 192.168.88.10                                               # The address or hostname of the AMF.
  bind_addr: 192.168.88.233                                            # A local IP that the gNB binds to for traffic from the AMF.

ru_ofh:
  ru_bandwidth_MHz: 100                                           # RU instantaneous bandwidth.
  t1a_max_cp_dl: 500                                              # Maximum T1a on Control-Plane for Downlink in microseconds.
  t1a_min_cp_dl: 250                                              # Minimum T1a on Control-Plane for Downlink in microseconds.
  t1a_max_cp_ul: 465                                              # Maximum T1a on Control-Plane for Uplink in microseconds.
  t1a_min_cp_ul: 250                                              # Minimum T1a on Control-Plane for Uplink in microseconds.
  t1a_max_up: 250                                                 # Maximum T1a on User-Plane in microseconds.
  t1a_min_up: 80                                                  # Minimum T1a on User-Plane in microseconds.
  ta4_max: 500                                                    # Maximum Ta4 on User-Plane in microseconds.
  ta4_min: 25                                                     # Minimum Ta4 on User-Plane in microseconds.
  is_prach_cp_enabled: true                                      # Configures if Control-Plane messages should be used to receive PRACH messages.
  ignore_ecpri_payload_size: true
  compr_method_ul: bfp                                            # Uplink compression method.
  compr_bitwidth_ul: 8                                            # Uplink IQ samples bitwidth after compression.
  compr_method_dl: bfp                                            # Downlink compression method.
  compr_bitwidth_dl: 8                                            # Downlink IQ samples bitwidth after compression.
  compr_method_prach: bfp                                         # PRACH compression method.
  compr_bitwidth_prach: 8                                         # PRACH IQ samples bitwidth after compression.
  enable_ul_static_compr_hdr: true                                # Configures if the compression header is present for uplink User-Plane messages (false) or not present (true).
  enable_dl_static_compr_hdr: true                                # Configures if the compression header is present for downlink User-Plane messages (false) or not present (true).
  iq_scaling: 5.5                                                # IQ samples scaling factor applied before compression, should be a positive value smaller than 10.
  cells:
    - network_interface: enp1s0f1                                 # Ethernet interface name used to communicate with the RU.
      ru_mac_addr: 0C:83:CC:0F:E9:04                              # RU MAC address.
      du_mac_addr: 98:b7:85:1e:e7:f0                              # DU MAC address.
      vlan_tag: 564                                                 # VLAN tag value.
#      prach_port_id: [4]                                          # PRACH eAxC port value.
#      dl_port_id: [0, 1]                                          # Downlink eAxC port values.
#      ul_port_id: [0]                                          # Uplink eAxC port values.
      prach_port_id: [4, 5, 6, 7]                                 # PRACH eAxC port values.
      dl_port_id: [0]                                             # Downlink eAxC port values.
      ul_port_id: [0, 1, 2, 3]                                    # Uplink eAxC port values.

cell_cfg:
  dl_arfcn: 641676                                                # ARFCN of the downlink carrier (center frequency).
  band: 78                                                        # The NR band.
  channel_bandwidth_MHz: 100                                      # Bandwith in MHz. Number of PRBs will be automatically derived.
  common_scs: 30                                                  # Subcarrier spacing in kHz used for data.
  plmn: "31501"                                                   # PLMN broadcasted by the gNB.
  tac: 1                                                          # Tracking area code (needs to match the core configuration).
  pci: 1                                                          # Physical cell ID.
#  nof_antennas_dl: 2                                              # Downlink number of antennas.
#  nof_antennas_ul: 1                                              # Uplink number of anntennas.
  nof_antennas_dl: 1                                              # Number of transmission antennas.
  nof_antennas_ul: 1                                              # Number of reception antennas.
  prach:
#    prach_config_index: 7                                          # PRACH configuration index.
#    prach_root_sequence_index: 1                                  # PRACH root sequence index.
#    zero_correlation_zone: 0                                      # Zero correlation zone.
#    prach_frequency_start: 0                                      # Offset in PRBs of lowest PRACH transmission occasion in frequency domain respective to PRB 0.
    prach_config_index: 159                                       # PRACH configuration index.
    prach_root_sequence_index: 1                                  # PRACH root sequence index.
    zero_correlation_zone: 0                                      # Zero correlation zone.
    prach_frequency_start: 12                                     # Offset in PRBs of lowest PRACH transmission occasion in frequency domain respective to PRB 0.

log:
  filename: /var/log/srsran/gnb.log
#/home/malin/gnb.log                                          # Path of the log file.
  all_level: info                                              # Logging level applied to all layers.

pcap:
  ngap_filename: /tmp/gnb_ngap.pcap     # Optional TEXT (/tmp/gnb_ngap.pcap). Path for NGAP PCAPs. 
  ngap_enable: false                    # Optional BOOL (false). Enable/disable NGAP packet capture.
  e1ap_filename: /tmp/gnb_e1ap.pcap     # Optional TEXT (/tmp/gnb_e1ap.pcap). Path for E1AP PCAPs. 
  e1ap_enable: false                    # Optional BOOL (false). Enable/disable E1AP packet capture.
  f1ap_filename: /tmp/gnb_f1ap.pcap     # Optional TEXT (/tmp/gnb_f1ap.pcap). Path for F1AP PCAPs. 
  f1ap_enable: false                    # Optional BOOL (false). Enable/disable F1AP packet capture.
  rlc_filename: /tmp/gnb_rlc.pcap       # Optional TEXT (tmp/gnb_rlc.pcap). Path for RLC PCAPs. 
  rlc_rb_type: all                      # Optional TEXT. Sets the RLC PCAP RB type. Supported: [all, srb, drb].
  rlc_enable: false                     # Optional BOOL (false). Enable/disable RLC packet capture.  
  mac_filename: /tmp/gnb_mac.pcap       # Optional TEXT (/tmp/gnb_mac.pcap). Path for MAC PCAPs. 
  mac_type: udp                         # Optional TEXT (udp). Sets the MAC PCAP pcap type. Supported: [DLT or UDP].
  mac_enable: false                     # Optional BOOL (false). Enable/disable MAC packet capture.
  e2ap_filename: /tmp/gnb_e2ap.pcap     # Optional TEXT (/tmp/gnb_e2ap.pcap). Path for E2AP PCAPs. 
  e2ap_enable: false                    # Optional BOOL (false). Enable/disable E2AP packet capture.
  gtpu_filename: /tmp/gnb_gtpu.pcap     # Optional TEXT (/tmp/gnb_gtpu.pcap). Path for GTPU PCAPs. 
  gtpu_enable: false                    # Optional BOOL (false). Enable/disable GTPU packet capture.

Expected Behavior

I don't exactly know what is the expected behavior but we have tested it with zmq base architecture and this is suppose to be expected behavior:

2024-03-06T07:15:11.053244 [DU-F1   ] [I] F1 Setup: Sending F1 Setup Request to CU-CP...
2024-03-06T07:15:11.053330 [DU-F1   ] [I] F1 Setup: Procedure completed successfully.
2024-03-06T07:15:11.053399 [SCHED   ] [I] [     0.0] cell=0: Cell configured successfully.
2024-03-06T07:15:11.067794 [DU-MNG  ] [I] DU manager started successfully.
2024-03-06T07:15:11.067797 [DU      ] [I] DU-High started successfully
2024-03-06T07:15:11.067800 [DU      ] [I] DU started successfully
2024-03-06T07:15:11.067800 [GNB     ] [I] Starting Radio Unit...
2024-03-06T07:15:11.067820 [GNB     ] [I] Radio Unit started successfully
2024-03-06T07:15:12.067812 [zmq:tx:0:0] [I] Waiting for request.
2024-03-06T07:15:12.067849 [zmq:rx:0:0] [I] Waiting for data.
2024-03-06T07:15:12.067897 [zmq:rx:0:0] [I] Waiting for reading samples. Completed 0 of 11520 samples.
2024-03-06T07:15:13.067814 [zmq:tx:0:0] [I] Waiting for request.
2024-03-06T07:15:13.067850 [zmq:rx:0:0] [I] Waiting for data.
2024-03-06T07:15:13.067903 [zmq:rx:0:0] [I] Waiting for reading samples. Completed 0 of 11520 samples.
2024-03-06T07:15:13.769620 [GNB     ] [I] Stopping Radio Unit...

Actual Behaviour

Instead what I am getting is this:

2024-03-12T05:36:04.706010 [OFH     ] [W] Missed incoming User-Plane PRACH messages for slot '477.17' and sector#0
2024-03-12T05:36:04.707012 [OFH     ] [W] Missed incoming User-Plane PRACH messages for slot '477.19' and sector#0
2024-03-12T05:36:04.711014 [OFH     ] [W] Missed incoming User-Plane PRACH messages for slot '478.7' and sector#0
2024-03-12T05:36:04.712014 [OFH     ] [W] Missed incoming User-Plane PRACH messages for slot '478.9' and sector#0

Additional Information

Basically I tested with a 5g device with a 5g sim. But my device couldn't find the network and this is appearing. What is the meaning of this message?? And what is the usual solution of this?

Thank you.

[aibtw]

I am no expert but I have an addition that might help someone else to understand the problem better. I noticed that even when I was able to get time sync and connected UE to RU successfully, I still got Missed incoming User-Plane PRACH very frequently.

So this makes me think it might be something else other than timing?

[ehitimum]

I am no expert but I have an addition that might help someone else to understand the problem better. I noticed that even when I was able to get time sync and connected UE to RU successfully, I still got Missed incoming User-Plane PRACH very frequently.

So this makes me think it might be something else other than timing?

Is it possible for you to provide your .log result and also srsran config file so that I can compare it with mine. Also I myself wanted to connect UE with RU so it will be helpful. This is my email: [email protected]

Thank You for your feedback.

[andrepuschmann]

What RU are you using?

[merimdzaferagic]

I am no expert but I have an addition that might help someone else to understand the problem better. I noticed that even when I was able to get time sync and connected UE to RU successfully, I still got Missed incoming User-Plane PRACH very frequently. So this makes me think it might be something else other than timing?

Is it possible for you to provide your .log result and also srsran config file so that I can compare it with mine. Also I myself wanted to connect UE with RU so it will be helpful. This is my email: [email protected]

Thank You for your feedback.

What RU are you using and what are you using to sync the DU and RU? Did you mange to connect your UE to the RU at any point in time?