[srsran-users] COTS UE does not see the 5G network

[Mehdi jafarizadeh]

Hi srsRAN Team,



As a new srsRAN user, I followed the instructions in *docs.srsran.com
<http://docs.srsran.com>* to setup end-to-end LTE as well as SA/NSA 5G labs
with a COTS UE:

   - Core- Open5Gs v2.4.5
   - Radio- BladeRF xA4
   - O-RAN- srsRAN
   - UE- Samsung Galaxy S21+ 5G (SM-G996W)



Here is the outcome- The end-to-end LTE network works fine. Though some
“GTP Failed” warnings appeared in Open5Gs, the UE found and connected to
the LTE network successfully. However, in either SA or NSA 5G networks, the
UE could not connect to the network. In both cases, the srsRAN successfully
established the connection with MME, but it seems that UE could not find
the network.



Here is our configuration for nr_cell in* rr.conf:*

nr_cell_list =
(
  {
    rf_port = 0;
    cell_id = 1;
    root_seq_idx = 1;
    tac = 7;
    pci = 500;
    dl_arfcn = 526200;
    band = 7;
  }
);

And here is the output from *srsRAN* console:

Active RF plugins: libsrsran_rf_soapy.so libsrsran_rf_blade.so
Inactive RF plugins:
---  Software Radio Systems LTE eNodeB  ---

Reading configuration file enb.conf...
WARNING: cpu0 scaling governor is not set to performance mode. Realtime
processing could be compromised. Consider setting it to performance mode
before running the application.

Built in Release mode using commit f2dff0b7a on branch master.

Opening 1 channels in RF device=default with args=default
Supported RF device list: soapy bladeRF file
Trying to open RF device 'soapy'
NG connection successful
No Soapy devices found.
Unable to open RF device 'soapy'
Trying to open RF device 'bladeRF'
Opening bladeRF...
[INFO @ host/libraries/libbladeRF/src/helpers/version.c:79] Firmware
version (v2.4.0) is newer than entries in libbladeRF's compatibility table.
Please update libbladeRF if problems arise.
Set RX sampling rate 1.92 Mhz, filter BW: 1.92 Mhz
RF device 'bladeRF' successfully opened

==== eNodeB started ===
Type <t> to view trace
Set RX sampling rate 11.52 Mhz, filter BW: 9.22 Mhz
Setting frequency: DL=2631.0 Mhz, UL=2511.0 MHz for cc_idx=0 nof_prb=52
set TX frequency to 2631000000
set RX frequency to 2510999998

And the tail of the *Open5Gs* logs:

05/27 18:44:28.797: [amf] INFO: gNB-N2 accepted[127.0.1.1]:50078 in ng-path
module (../src/amf/ngap-sctp.c:105)
05/27 18:44:28.797: [amf] INFO: gNB-N2 accepted[127.0.1.1] in master_sm
module (../src/amf/amf-sm.c:619)
05/27 18:44:28.797: [amf] INFO: [GNB] max_num_of_ostreams : 30
(../src/amf/context.c:854)
05/27 18:44:28.797: [amf] INFO: [Added] Number of gNBs is now 1
(../src/amf/context.c:869)


Unlike LTE, the logs does NOT reflect that the UE tries to connect. So, I
suspected maybe UE operates in a different band from those that are
supported by srsRAN. *However we tried all the supported bands (nr3, nr7,
and nr20) and none worked.* Any help to find the root cause of this problem
is really appreciated.

Thanks
-- 
Mehdi Jafarizadeh
5G Application Developer @ Shabodi
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