High unstable BLER with RAN550 #611
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Hi all, we are facing some problems with Benetel RAN550, Maybe someone can help us troubleshoot/solve the issue. Setup details:
We are using LLS-C3 setup. The GM330 works as a grandmaster clock. A vlan was set with tag 5. Both DU machine and RU were connected to Protempis. PTP is started on the DU: PHC2SYS started on DU: RU rebooted and got PTP lock, as seen below At this stage, we were able to run srsRAN gNB and attemp to connect a COTS UE (used multiple ones, all with same behavior, including OnePlus Nord 5G & OnePlus 10T 5G). BehaviorBasically, highly unstable UL BLER when running UDP (or even TCP) iperf. Even DL BLER is not very stable, as seen below for a stationary UE. The values sometimes go up to 80% and sometimes down to 20%, but never become stable for long periods of time. Also, it seems BLER is very sensitive to UE movement (which is not the case if we compare to a setup with USRP N310 for example).
We can confirm no late or early frames detected by the RU: Configurations, logs, pcapsPlease note that we tried IQ scaling = 10, and dmrs position = 2, as we saw in some suggestions to some other posts, but weren't able to see difference. Also, 100MHz bandwidth is not working for us, even with DPDK. Finally, we tried with and without DPDK, 4x4 and 4x2, but also saw no noticeable difference. amf:
addr: 127.0.1.100 # The address or hostname of the AMF.
bind_addr: 127.0.0.1 # A local IP that the gNB binds to for traffic from the AMF.
ru_ofh:
#ru_bandwidth_MHz: 20 # RU instantaneous bandwidth.
t1a_max_cp_dl: 470 # Maximum T1a on Control-Plane for Downlink in microseconds.
t1a_min_cp_dl: 419 # Minimum T1a on Control-Plane for Downlink in microseconds.
t1a_max_cp_ul: 336 # Maximum T1a on Control-Plane for Uplink in microseconds.
t1a_min_cp_ul: 285 # Minimum T1a on Control-Plane for Uplink in microseconds.
t1a_max_up: 345 # Maximum T1a on User-Plane in microseconds.
t1a_min_up: 294 # Minimum T1a on User-Plane in microseconds.
ta4_max: 200 # Maximum Ta4 on User-Plane in microseconds.
ta4_min: 0 # Minimum Ta4 on User-Plane in microseconds.
is_prach_cp_enabled: true # Configures if Control-Plane messages should be used to receive PRACH messages.
is_dl_broadcast_enabled: false # Optional BOOLEAN (0). Sets downlink broadcast enabled flag. Supported: [0, 1]. (This is a workaround for SISO, set to false or commenct it for mimo)
#ignore_ecpri_payload_size: 1 # Optional BOOLEAN (0). Sets whether or not to ignore eCPRI payload size field value. Supported [0. 1].
compr_method_ul: bfp # Uplink compression method.
compr_bitwidth_ul: 9 # Uplink IQ samples bitwidth after compression.
compr_method_dl: bfp # Downlink compression method.
compr_bitwidth_dl: 9 # Downlink IQ samples bitwidth after compression.
compr_method_prach: bfp # PRACH compression method.
compr_bitwidth_prach: 9 # PRACH IQ samples bitwidth after compression.
enable_ul_static_compr_hdr: false # Configures if the compression header is present for uplink User-Plane messages (false) or not present (true).
enable_dl_static_compr_hdr: false # Configures if the compression header is present for downlink User-Plane messages (false) or not present (true).
iq_scaling: 7 # IQ samples scaling factor applied before compression, should be a positive value smaller than 10.
cells:
#- network_interface: 0000:01:00.1 # Ethernet interface name used to communicate with the RU.
- network_interface: enp1s0f3np3
ru_mac_addr: xx:xx:xx:xx:xx:xx # RU MAC address.
du_mac_addr: xx:xx:xx:xx:xx:xx # DU MAC address.
#vlan_tag: 5 # VLAN tag value.
vlan_tag_cp: 5 # VLAN tag value for C-Plane.
vlan_tag_up: 5 # VLAN tag value for U-Plane.
prach_port_id: [4, 5, 6, 7] # PRACH eAxC port value.
dl_port_id: [0,1,2,3] # Downlink eAxC port values.
ul_port_id: [0,1,2,3] # Uplink eAxC port values.
cell_cfg:
dl_arfcn: 640000 # ARFCN of the downlink carrier (center frequency).
band: 78 # The NR band.
channel_bandwidth_MHz: 20 # Bandwith in MHz. Number of PRBs will be automatically derived.
common_scs: 30 # Subcarrier spacing in kHz used for data.
plmn: "99970" # PLMN broadcasted by the gNB.
tac: 7 # Tracking area code (needs to match the core configuration).
pci: 1 # Physical cell ID.
nof_antennas_dl: 4 # Downlink number of antennas.
nof_antennas_ul: 4 # Downlink number of antennas.
prach:
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: 2
tdd_ul_dl_cfg:
dl_ul_tx_period: 10 # Optional INT (10). Sets the TDD pattern periodicity in slots. The combination of this value and the chosen numerology must lead to a TDD periodicity of 0.5, >
nof_dl_slots: 7 # Optional INT (6). Number of consecutive full Downlink slots. Supported: [0-80].
nof_dl_symbols: 6 # Optional INT (0). Number of Downlink symbols at the beginning of the slot following full Downlink slots. Supported: [0-13].
nof_ul_slots: 2 # Optional INT (3). Number of consecutive full Uplink slots. Supported: [0 - 80].
nof_ul_symbols: 4
ssb:
ssb_period: 20
pdsch:
mcs_table: qam256I uploaded logs and pcaps to drive: RU configs are set to PRACH short format and dynamic compression. Would appreciate the help. |
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Replies: 1 comment 2 replies
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Hi @AzeezEbrahim, Thanks for your report. Unfortunately, we haven't been able to get a stable connection either using 20 MHz. For this RU, the best is to use 100 MHz. Can you share the issues you had with that configuration? With any other BW, the iq scaling might need to be adjusted. Can you run the oru_dpd_stats command in the RU to check that the DPD has no error and the inñut power is less than -13 dB? |
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Regarding DPD stats, I would really appreciate your help in making sense of the output. Which is the "input power" you are referring to? and what's the sweet spot to look for? this output is from a 4x4 20MHz setup (4.5 iq scaling). Regarding the 100MHz bandwidth, it worked for me in a C4 setup only. In that setup, I can clearly see low DL BLER (almost 0). But the uplink is still unstable. |
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Hi @AzeezEbrahim , first of all, at this point you need to check with Benetel. From what I can tell:
If it works with C4 and it doesn't with C3, most likely the issue is on the RU side. |
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Hi @AzeezEbrahim , first of all, at this point you need to check with Benetel. From what I can tell:
dpdErrorCode: 13319is clearly not gooddpdMeanTuPower: -22.084129I think should be closer to -13 when doing full rate, so you can increase the iq_scale maybeIf it works with C4 and it doesn't with C3, most likely the issue is on the RU side.