UE cannot see the 5G SA network

[alvaroalfaro612]

Hello,

I am trying to create a network with srsRAN project and Open5Gs. The connection between both seems to be working looking at the Open5Gs logs:

03/14 16:21:38.801: [amf] INFO: gNB-N2 accepted[127.0.0.1] in master_sm module (../src/amf/amf-sm.c:668)
03/14 16:21:38.801: [amf] INFO: [Added] Number of gNBs is now 1 (../src/amf/context.c:973)
03/14 16:21:38.801: [amf] INFO: gNB-N2[127.0.0.1] max_num_of_ostreams : 30 (../src/amf/amf-sm.c:707)

But the UE (Xiami Redmi Note 5G) is not able to see the network when looking manually for it.

I have the same problem with srsRAN 5G SA, while srsRAN 4G network is working fine.

I have already tried all of the recommendation of this app note :

• Tried with different and even commercial PLMN for the SIM.
• Forcing 5G connection with NSG android app.
• Run the deactivate-5g.script for USIM configuration.

Anyone knows what can be happening?

Thanks in advance!

[gustavobsch]

Are you using a GPSDO on your SDR? you should read notes in #10

[alvaroalfaro612]

Today I am going to try again with an external clock. I will check also the information you provide in the link, thanks!

[alvaroalfaro612]

After trying with a GPSDO, I am still not able to see the network.

Depending of the band configuration I see one or two Late, underflow, overflow messages.

Also, after checking my UE here Xiaomi Redmi Note 10 5G, it seems that it is only to use SA at bands 28 and 41, so I am using these bands. Also tried with Poco F3 and also it is not seeing the network.

I don´t really know what should I try now...

[gustavobsch]

You might need to enable debugging and provide some logs

[alvaroalfaro612]

This is the YAML file for gnb 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.

rf_driver:
  device_driver: uhd                # The RF driver name.
  device_args: type=b200,clock=external            # Optionally pass arguments to the selected RF driver.
  clock:                            # Specify the clock source used by the RF.
  sync:                             # Specify the sync source used by the RF.
  srate: 30.72                    # RF sample rate might need to be adjusted according to selected bandwidth.
  tx_gain: 50                       # 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: 537999                 # ARFCN of the downlink carrier (center frequency).
  band: 41                          # The NR band.
  channel_bandwidth_MHz: 30         # Bandwith in MHz. Number of PRBs will be automatically derived.
  common_scs: 15                    # Subcarrier spacing in kHz used for data.
  plmn: "00102"                     # PLMN broadcasted by the gNB.
  tac: 7                            # Tracking area code (needs to match the core configuration).
  pci: 1                            # Physical cell ID.
      
log:
  filename: ./tmp/gnb.log            # Path of the log file.
  all_level: warning                # Logging level applied to all layers.

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.

Logs from the Open5Gs:

03/15 15:42:44.183: [amf] INFO: gNB-N2 accepted[127.0.0.1]:48263 in ng-path module (../src/amf/ngap-sctp.c:113)
03/15 15:42:44.183: [amf] INFO: gNB-N2 accepted[127.0.0.1] in master_sm module (../src/amf/amf-sm.c:668)
03/15 15:42:44.183: [amf] INFO: [Added] Number of gNBs is now 1 (../src/amf/context.c:973)
03/15 15:42:44.183: [amf] INFO: gNB-N2[127.0.0.1] max_num_of_ostreams : 30 (../src/amf/amf-sm.c:707)

Logs from srsRAN:

2023-03-15T14:49:46.296275 [RF ] [W] Radio realtime event: Type=start-of-burst Source=tx Timestamp=70170411
2023-03-15T14:50:43.940790 [RF ] [W] Radio realtime event: Type=end-of-burst Source=tx Timestamp=na
2023-03-15T14:50:43.941427 [ALL ] [E] Cannot push anymore tasks into the radio worker queue. maximum size is 2048

Stdout from srsRAN:

Available radio types: uhd.

--== srsRAN gNB (commit 0523be6) ==--

[INFO] [UHD] linux; GNU C++ version 9.4.0; Boost_107100; UHD_4.4.0.HEAD-0-g5fac246b
Making USRP object with args 'type=b200,clock=external'
Cell pci=1, bw=30 MHz, dl_arfcn=537999 (n41), dl_freq=2689.995 MHz, dl_ssb_arfcn=536910, ul_freq=2689.995 MHz

==== gNodeB started ===
Type to view trace

Everything seems to be working but I cannot see the network.

[gustavobsch]

Did you try the default Yaml config that comes with srsRAN gNB? maybe you can try to lower the bandwidth. Try different gain settings, increase the TX gain, I noticed 80 works best with my b210. Also did you try specifying the clock and sync on these fields?

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

[alvaroalfaro612]

Yes, but those config files are for n78 and n3, and my UE is not prepared for using these bands.
Also, I have tried in the YAML file with:

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

and

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

but in both case srsGNB is not able to create the radio session (stout):

Available radio types: uhd.

--== srsRAN gNB (commit 0523be6) ==--

[INFO] [UHD] linux; GNU C++ version 9.4.0; Boost_107100; UHD_4.4.0.HEAD-0-g5fac246b
Making USRP object with args 'type=b200l'
srsGNB ERROR: Unable to create radio session.

It is possible that I am still not using the GPSDO connected to my USRP B200 mini REF connector? Which will be the correct configuration file for use it properly?

Thanks again!

[gustavobsch]

Check the B200 can correctly sync with the external reference

~/uhd/host/build/examples$ ./test_clock_synch

[alvaroalfaro612]

test_clock_synch is not working for me. I think is because internally is doing:

usrp->set_clock_source("gpsdo");
usrp->set_time_source("gpsdo");

And this command is for internally connected gpsdo,and what I have is an external gpsdo providing a 10MHz signal connected to the REF SMA of my USRP b200 mini. I guess it should be use "external" instead for this case. Does this makes sense?

[gustavobsch]

Yes you are correct, it should be external, not gpsdo

[alvaroalfaro612]

Runnning tx_samples_from_file with --ref=external can be used for checking if external clock is being used. However, I will not be able to test the external gpsdo again until Monday. I will update here the result.
Thanks again for the help.

[ToOpenSky]

Hi, @alvaroalfaro612 , did you able to solve your problem (this thread)?

[herlesupreeth]

@alvaroalfaro612 your channel bandwidth is not correct for sampling rate (srate) of 30.72 MHz. Please change your channel bandwidth to 20 MHz

[gmaruzz]

for Xiaomi, Poco, Redmi phones, (at least older ones) you MUST activate SA 5G mode, calling feature code

*#*#726633#*#*

then go to Sim Cards & mobile networks (before choosing which SIM), Advanced Settings, and activate SA mode

https://en.ocworkbench.com/how-to-enable-5g-sa-option-on-xiaomi-redmi-poco-5g-phones/

[tiger762]

Having the exact same problem here. Kali 21 Linux, dual i5 laptop, Ettus B200, external 10MHz GPSDO, iPhone 12 (iOS 16.4.1 with "5G ON" option checked). Latest and greatest srsRAN_Project. This is my config file (n71, 5MHz):

amf:
addr: 192.168.16.254 # The address or hostname of the AMF.
bind_addr: 192.168.16.1 # A local IP that the gNB binds to for traffic from the AMF.

rf_driver:
device_driver: uhd # The RF driver name.
device_args: type=b200,num_recv_frames=64,num_send_frames=64,clock=external # Optionally pass arguments to the selected RF driver.
clock: # Specify the clock source used by the RF.
sync: external # Specify the sync source used by the RF.
srate: 5.76 # RF sample rate might need to be adjusted according to selected bandwidth.
otw_format: sc12
tx_gain: 89 # Transmit gain of the RF might need to adjusted to the given situation.
rx_gain: 50 # Receive gain of the RF might need to adjusted to the given situation.

cell_cfg:
dl_arfcn: 129000 # ARFCN of the downlink carrier (center frequency).
band: 71 # 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: "310690" # PLMN broadcasted by the gNB.
tac: 7 # Tracking area code (needs to match the core configuration).
pci: 1 # Physical cell ID.

log:
filename: /tmp/gnb.log # Path of the log file.
all_level: info # Logging level applied to all layers.

pcap:
mac_enable: true # Set to true to enable MAC-layer PCAPs.
mac_filename: /tmp/gnb_mac.pcap # Path where the MAC PCAP is stored.
ngap_enable: true # Set to true to enable NGAP PCAPs.
ngap_filename: /tmp/gnb_ngap.pcap # Path where the NGAP PCAP is stored.

Here is a spectral analysis of n71 in the lab. That is T-Mobile's 15MHz (622-637) and my 5MHz centered at 645MHz (ARFCN 129000)

[tiger762]

Using a OnePlus Nord N200 5G now, as shown in the list of COTS UE that are known to work.

Does not work in n71 (645 MHz). Does not work in n2 (1945 MHz). Using a hand-held spectrum analyzer to find 'quiet' sections of licensed spectrum to use. Also to confirm that the signal is strong enough, i.e. the antenna has low return loss (S11)

Using the config file I posted above, just tweaking the band and the ARFCN. From OnePlus site:

5GNR: n2,25,41,66,71

What is the magic / secret to getting a UE to see the GNB? 4G/LTE was a pain, but it was not this bad. Thanks in advance.

[herlesupreeth]

Does not work in n71 (645 MHz)

It could be that phone may not be supporting/enabled that band (quite contrary to what they advertise in spec about bands supported)

In order to know the bands supported by the handset please refer to the UERadioCapability information in MAC pcap (can be enabled in config), in there check for supportedBandListNR field.