[srslte-users] Some commercial UEs can't detect the enb

[Yi Chu]

Dear community,

I have been testing srslte with a few different commercial UEs, some worked
perfectly and some couldn't find the enb after network search. I found
several similar issues such as this one
http://www.softwareradiosystems.com/pipermail/srslte
-users/2019-November/003153.html
but none of these really reached a conclusion. Here is my setup:

A Ubuntu 18.04 laptop, srsenb and srsepc on the physical machine. I have
been testing VoLTE as well so I have Open5GS (nextepc) running on a virtual
machine, and I switch between the two EPC frequently. I have tested Band 7
DL=2.65GHz and UL=2.53GHz, also Band 1 DL=2.16GHz and UL=1.97GHz. The radio
is a USRP B205mini (main USRP) and a USRP X300. PRB is 25. The USIM is from
opencells. One the same laptop I have a working OAI (enb+epc) as well so I
also run this setup to test the UEs.

I have tested 6 commercial smartphones and here are the results.
1. Huawei P30 with stock Android 10 (unroot): so far the most favourable UE.
It works with srsenb+srsepc, srsenb+open5gs, and OAI enb+epc, both Bands 1
and 7, and two mcc/mnc combinations 00101 and 20892.

2. IPhone 7 with IOS 12: it starts to get odd from here. It works with OAI
enb+epc on both LTE bands, with mcc/mnc 20892. Once I switch to srsenb+
srsepc, the UE can't find the enb in network search.

3. Samsung S5: I first tested it when it had the stock Android 4 (unroot
and yes it's old), it worked fine with srsenb+srsepc and OAI enb+epc, mcc/
mnc=20892, band 7. The I flashed Lineage 16 (Android 9, unroot) on it and
updated the firmware, the UE stops seeing either srsenb or OAI enb.

4. There are three UEs that can't find either srsenb or OAI enb on either
LTE bands in network search. MI Mix2 (Android 8, unroot), Samsung A10
(Android 9, unroot) and Samsung A20e (Android 10, root). The Samsung UEs
don't seem to support mcc=001 so I have tested 20892 and but no luck. I'm
using the same USIM which just worked on the Huawei UE. I have also tested
these with USRP X300 but the results are the same.

I have no clue what could cause the inconsistency of the IPhone 7, the
results of the Samsung S5 is very strange as well, it looks like updating
the firmware has made some impact.

Anyone has any ideas of further tests/debug I can do, please let me know,
many thanks!

Best regards
Yi
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