[srslte-users] Attaching a UE to srsENB

Sat Feb 24 18:08:55 UTC 2018

Hi all,

I'm facing a similar issue, but could trick the (commercial) UE to attach. If I understand this correctly, two separate things happen here:

1. UE wants EPS and non-EPS services

srsEPC sends Attach Accept with attach result "EPS only". Therefore UE triggers TAU with "Combined TA/LA update with IMSI attach" to register non-EPS services. I avoid that by setting the attach result from
>  attach_accept.eps_attach_result = LIBLTE_MME_EPS_ATTACH_RESULT_EPS_ONLY;
to
>  attach_accept.eps_attach_result = LIBLTE_MME_EPS_ATTACH_RESULT_COMBINED_EPS_IMSI_ATTACH;
https://github.com/srsLTE/srsLTE/blob/bedd154fb1433ff1bbe2c415d558271b3eff656d/srsepc/src/mme/s1ap_nas_transport.cc#L1096

Of course that's not a solution to the actual problem. Not sure how to handle "TAU with non-EPS services request" correctly. Sending a dummy TAU accept didn't help much.

2. Service Request not handled

I think Service Request is currently not handled by srsEPC, but that's only a problem that occurs when UE re-establishes RRC connection while in ECM-Connected state. It might not occur if you change the attach request to combined IMSI attach and set a high rrc_inactivity_timer in enb.conf.

Another solution is to implement Service Reject with LIBLTE_MME_EMM_CAUSE_IMPLICITLY_DETACHED, which will cause the UE to perform a full re-attach.

Best regards,
Merlin Chlosta

On 23.02.2018 10:57, Moncef Nabil Boukhatem wrote:
> Sorry I forgot them. Here they are.
> 
> Thank you for your help,
> 
> BEst regards,
> 
> BOUKHATEM Moncef NAbil
> 
> ----- Mail original -----
> De: "Andre Puschmann" <andre.puschmann at softwareradiosystems.com>
> À: "Moncef Nabil Boukhatem" <moncef.boukhatem at telecom-paristech.fr>, "Ismael Gomez" <ismael.gomez at softwareradiosystems.com>
> Cc: "srslte-users" <srslte-users at lists.softwareradiosystems.com>
> Envoyé: Jeudi 22 Février 2018 20:44:03
> Objet: Re: [srslte-users] Attaching a UE to srsENB
> 
> On 22/02/18 19:10, Moncef Nabil Boukhatem wrote:
>> Hello,
>>
>> After managing to find my network with the different phones (even if I have some time to wait before finding it), I've faced this error :
>>
>> Unhandled feature in RRC function: liblte_rrc_unpack_rrc_connection_setup_complete_msg
> 
> That's just a warning rather than an error. What happens after that?
> 
>>
>> Do you have any idea about it? I join the logs and pcap of the srsenb.
> 
> Yes, please attach the logs and pcap.
> 
> Thanks
> Andre
> 
>>
>> Thank you for your help,
>>
>> Best regards,
>>
>> BOUKHATEM Moncef Nabil
>>
>> ----- Mail original -----
>> De: "Moncef Nabil Boukhatem" <moncef.boukhatem at telecom-paristech.fr>
>> À: "Ismael Gomez" <ismael.gomez at softwareradiosystems.com>
>> Envoyé: Jeudi 22 Février 2018 14:16:04
>> Objet: Re: [srslte-users] Attaching a UE to srsENB
>>
>> Hello,
>>
>> I used a beamforming trick using a box and I can finally see the network on my phone. I can also see the RACH in the trace of the eNB but there is the RRC Connection Release problem when taking a look to the pcap (you'll find it attached with the logs) (I've also filed the db_user.csv)
>>
>> I think that one member did find the solution but I'm not sure, I will look for it.
>>
>> Thank you for your help,
>>
>> Best regards,
>>
>> BOUKHATEM Moncef NAbil
>>
>> ----- Mail original -----
>> De: "Moncef Nabil Boukhatem" <moncef.boukhatem at telecom-paristech.fr>
>> À: "Ismael Gomez" <ismael.gomez at softwareradiosystems.com>
>> Envoyé: Jeudi 22 Février 2018 12:51:35
>> Objet: Re: [srslte-users] Attaching a UE to srsENB
>>
>> I've already tried that too, and still didn't change a thing.
>>
>> ----- Mail original -----
>> De: "Ismael Gomez" <ismael.gomez at softwareradiosystems.com>
>> À: "Moncef Nabil Boukhatem" <moncef.boukhatem at telecom-paristech.fr>
>> Envoyé: Jeudi 22 Février 2018 12:37:47
>> Objet: Re: [srslte-users] Attaching a UE to srsENB
>>
>> just place one antenna vertical and the other horizontal
>>
>> On Thu, 22 Feb 2018 at 12:36 Moncef Nabil Boukhatem <
>> moncef.boukhatem at telecom-paristech.fr> wrote:
>>
>>> Hello Ismael,
>>>
>>> Thank you for your answer,
>>>
>>> I've checked the connectors and the antennas and I'm transmitting on an
>>> empty frequency band that is supported by the phones. But I couldn't check
>>> the cross-polarization, how can I do it and if it's not cross-polarized how
>>> can I modify it, please?
>>>
>>> Thank you again for your help,
>>>
>>> Best regards,
>>>
>>> BOUKHATEM Moncef Nabil
>>>
>>> ----- Mail original -----
>>> De: "Ismael Gomez" <ismael.gomez at softwareradiosystems.com>
>>> À: "Moncef Nabil Boukhatem" <moncef.boukhatem at telecom-paristech.fr>
>>> Cc: "srslte-users" <srslte-users at lists.softwareradiosystems.com>
>>> Envoyé: Jeudi 22 Février 2018 10:13:58
>>> Objet: Re: [srslte-users] Attaching a UE to srsENB
>>>
>>> Make sure your connectors and antennas are correct. Make sure the antennas
>>> are cross-polarized. Make sure you are transmitting on an empty frequency
>>> band and that band is supported by your phones.
>>>
>>> On Tue, 20 Feb 2018 at 22:00 Moncef Nabil Boukhatem <
>>> moncef.boukhatem at telecom-paristech.fr> wrote:
>>>
>>>> Hello,
>>>>
>>>> I would like to attach a UE to my srsENB and I would like to know what
>>> are
>>>> the parameters to change in order to do it.
>>>>
>>>> My srsENB is working good with srsEPC. I've successfuly attached srsUE to
>>>> srsENB (Both USRP B210) but couldn't manage to make my network visible to
>>>> my UE (I've used many UEs : Xiaomi Redmi 4, Samsung Note 5, Iphone 5S and
>>>> SE; none of them could see the network even if they are all compatible
>>> with
>>>> the band I'm using).
>>>>
>>>> I think that the problem might be with the gain, the channel used is
>>>> visible by using a spectrum analyzer, but the power is very weak (less
>>> than
>>>> 1dB, I am using a USRP B210) even by putting the tx gain to 90 or 100 or
>>>> more, but I am not really sure about it.
>>>>
>>>> Thank you for your help,
>>>>
>>>> Best regards,
>>>>
>>>> BOUKHATEM Moncef Nabil
>>>> _______________________________________________
>>>> srslte-users mailing list
>>>> srslte-users at lists.softwareradiosystems.com
>>>> http://www.softwareradiosystems.com/mailman/listinfo/srslte-users
>>>>
>>>
>> _______________________________________________
>> srslte-users mailing list
>> srslte-users at lists.softwareradiosystems.com
>> http://www.softwareradiosystems.com/mailman/listinfo/srslte-users
>>
> 
> 
> 
> _______________________________________________
> srslte-users mailing list
> srslte-users at lists.softwareradiosystems.com
> http://www.softwareradiosystems.com/mailman/listinfo/srslte-users
> 