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

[Cedric Roux]

Hi,

maybe also some phones are "locked" and will only
accept certain PLMNs. 20892 may not be one of them.

For the list of PLMNs, see eg.
https://www.mcc-mnc.com/

On 2020-08-06 10:39, Paul Sutton wrote:
> Hi Yi,
> 
> Here are a few generic things to check:
> 
> 1) Make sure the entire signal bw is inside the band of use
>      - the DL/UL frequencies you're using should be fine
> 2) Check that there are no interfering signals on the frequencies of use
>      - B1 and B7 are fully allocated in the UK 
> (https://www.spectrummonitoring.com/frequencies/#UK) so use a Faraday 
> cage or check for existing carriers
> 3) use a GPSDO or external clock source, or make sure carrier frequency 
> offset is small enough
>      - Are you using an external clock source or do you have access to 
> equipment to check the frequency accuracy?
> 4) Enable logs on the eNodeB and check if PRACH is detected
> 5) Try adjusting tx_gain, reducing it or increasing. If the UE sees low 
> power (<pmax threshold), it won't PRACH
> 
> For the iPhone 7 case, you could compare PRACH, SIB1 and SIB2 
> configurations for differences between srsENB and OAI. You could also 
> add SIB3 configuration in case the UEs require it.
> 
> Are you using the default config files for everything except EARFCN? If 
> not, could you share your config files?
> 
> Best regards,
> Paul
> 
> On 05/08/2020 17:08, Yi Chu wrote:
>> 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 
>> <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
>>
>>
>> _______________________________________________
>> srslte-users mailing list
>> srslte-users at lists.softwareradiosystems.com
>> http://www.softwareradiosystems.com/mailman/listinfo/srslte-users
> 
> -- 
> ________________________________________________________________
> Paul Sutton Ph.D.
> 
> Software Radio Systems (SRS)
> http://www.softwareradiosystems.com
> paul at softwareradiosystems.com
> 
> PGP Key ID: 3B4A5292
> Fingerprint: B0AC 19C9 B228 A6EB 86E1 82B2 90C7 EC95 3B4A 5292
> ________________________________________________________________
> 
> 
> _______________________________________________
> srslte-users mailing list
> srslte-users at lists.softwareradiosystems.com
> http://www.softwareradiosystems.com/mailman/listinfo/srslte-users
>