[srsran-users] ul_freq is wrong when dl_arfcn is less than 153620 in band n28

[sindi at innovatechtelecom.com]

Hi,

 

I´ve been testing gNB in band n28 with COTS UE for 5MHz channel bandwidth
using Open5GS. The gNB works fine unless when the dl_arfcn is less than
152620. For instance, when dl_arfcn = 153600, it results that the dl_freq <
ul_freq. Below are the outputs for dl_arfcn=153620 and dl_arfcn=153600.
Also, there is the gNB configuration for dl_arfcn = 153600 that results in
dl_freq < ul_freq. Regards, Sindi

 

 

--== srsRAN gNB (commit a09b0008e) ==--

 

Connecting to AMF on 127.0.0.5:38412

Available radio types: uhd.

[INFO] [UHD] linux; GNU C++ version 11.4.0; Boost_107400;
UHD_4.6.0.0-0ubuntu1~jammy1

[INFO] [LOGGING] Fastpath logging disabled at runtime.

Making USRP object with args
'type=b200,num_recv_frames=64,num_send_frames=64'

[INFO] [B200] Detected Device: B200mini

[INFO] [B200] Operating over USB 3.

[INFO] [B200] Initialize CODEC control...

[INFO] [B200] Initialize Radio control...

[INFO] [B200] Performing register loopback test...

[INFO] [B200] Register loopback test passed

[INFO] [B200] Setting master clock rate selection to 'automatic'.

[INFO] [B200] Asking for clock rate 16.000000 MHz...

[INFO] [B200] Actually got clock rate 16.000000 MHz.

[INFO] [MULTI_USRP] Setting master clock rate selection to 'manual'.

[INFO] [B200] Asking for clock rate 23.040000 MHz...

[INFO] [B200] Actually got clock rate 23.040000 MHz.

Cell pci=1, bw=5 MHz, dl_arfcn=153620 (n28), dl_freq=768.1 MHz,
dl_ssb_arfcn=153650, ul_freq=713.1 MHz

 

==== gNodeB started ===

Type <t> to view trace

 

 

--== srsRAN gNB (commit a09b0008e) ==--

 

Connecting to AMF on 127.0.0.5:38412

Available radio types: uhd.

[INFO] [UHD] linux; GNU C++ version 11.4.0; Boost_107400;
UHD_4.6.0.0-0ubuntu1~jammy1

[INFO] [LOGGING] Fastpath logging disabled at runtime.

Making USRP object with args
'type=b200,num_recv_frames=64,num_send_frames=64'

[INFO] [B200] Detected Device: B200mini

[INFO] [B200] Operating over USB 3.

[INFO] [B200] Initialize CODEC control...

[INFO] [B200] Initialize Radio control...

[INFO] [B200] Performing register loopback test...

[INFO] [B200] Register loopback test passed

[INFO] [B200] Setting master clock rate selection to 'automatic'.

[INFO] [B200] Asking for clock rate 16.000000 MHz...

[INFO] [B200] Actually got clock rate 16.000000 MHz.

[INFO] [MULTI_USRP] Setting master clock rate selection to 'manual'.

[INFO] [B200] Asking for clock rate 23.040000 MHz...

[INFO] [B200] Actually got clock rate 23.040000 MHz.

Cell pci=1, bw=5 MHz, dl_arfcn=153600 (n28), dl_freq=768.0 MHz,
dl_ssb_arfcn=153630, ul_freq=798.0 MHz

 

==== gNodeB started ===

Type <t> to view trace

 

 

Configuration:

 

amf:

  addr: 127.0.0.5                                               # 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_sdr:

  device_driver: uhd                                            # The RF
driver name.

  device_args: type=b200,num_recv_frames=64,num_send_frames=64  # Optionally
pass arguments to the selected RF driver.

  clock: external                                               # Specify
the clock source used by the RF.

  sync:                                                         # Specify
the sync source used by the RF.

  srate: 23.04                                                  # RF sample
rate might need to be adjusted according to selected bandwidth.

  otw_format: sc12

  tx_gain: 85                                                   # Transmit
gain of the RF might need to adjusted to the given situation.

  rx_gain: 60                                                   # Receive
gain of the RF might need to adjusted to the given situation.

 

cell_cfg:

  dl_arfcn: 153600                                              # ARFCN of
the downlink carrier (center frequency).

  band: 28                                                      # The NR
band.

  channel_bandwidth_MHz: 5                                      # Bandwith
in MHz. Number of PRBs will be automatically derived.

  common_scs: 15                                                # Subcarrier
spacing in kHz used for data.

  plmn: "99970"                                                 # PLMN
broadcasted by the gNB.

  tac: 1                                                        # Tracking
area code (needs to match the core configuration).

  pci: 1                                                        # Physical
cell ID.

 

pcap:

  mac_enable: false                                             # Set to
true to enable MAC-layer PCAPs.

  mac_filename: /tmp/gnb_mac.pcap                               # Path where
the MAC PCAP is stored.

  ngap_enable: false                                            # Set to
true to enable NGAP PCAPs.

  ngap_filename: /tmp/gnb_ngap.pcap                             # Path where
the NGAP PCAP is stored.

 

 

 

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