[srslte-users] srsenb disconnection problem

Sat Oct 28 22:30:13 UTC 2017

Thanks. Please let me know if I can help in any way.

Nicola

On Oct 28, 2017 18:28, "Ismael Gomez" <ismael.gomez at softwareradiosystems.com>
wrote:

> Let me look into it and get back to you. We havent seen that issue in our
> lab. We've done very high loads for hours without any random access or
> losing the connection.
>
> El sáb., 28 oct. 2017 15:21, Nicola Bui <n.bui at northeastern.edu> escribió:
>
>> CFI is always set to 3 and I already tried with 50 rb, with the same
>> result: during high load the mobile performs a random access which succeeds
>> and cause the misalignment between epc and enb.
>> How can I get the cause of the "DCI can't be scheduled"?
>>
>> Thanks,
>> Nicola
>>
>>
>> On Oct 28, 2017 18:17, "Ismael Gomez" <ismael.gomez@
>> softwareradiosystems.com> wrote:
>>
>> Hi Nicola,
>>
>> I see you are using 25 PRB, what value you have for nof_ctrl_symbols in
>> enb.conf? Can you try setting it to 3 if you haven't already? If you have,
>> can you try with 50 PRB?
>>
>> In the logs it looks like the DCIs can't be scheduled. You can see log
>> messages like this:
>>
>> 13:54:15.964584 [MAC ] Warning [05901] SCHED: Could not schedule DL DCI
>> for rnti=0x46, pid=0
>>
>> You can also see that the eNodeB receives no PUCCH in messages like this:
>>
>> 13:54:15.965262 [PHY0] Info    [05898] PUCCH: rnti=0x46, corr=0.02,
>> n_pucch=20, n_prb=1, ack=0
>>
>> Look at corr value, it must be at least >0.8. This is because the UE
>> didn't receive the PDCCH grant and therefore is not sending the PUCCH ACK
>> signal.
>>
>> We use a quite conservative scheduler for PDCCH and it might try to use
>> highest aggregation level and it can't fit. I'll look into it, in the
>> meantime, can you try with 50 PRB and send me the log again if you see the
>> same issue?
>>
>> thanks
>>
>> On Fri, 27 Oct 2017 at 12:32 Nicola Bui <n.bui at northeastern.edu> wrote:
>>
>>> Another thing I just noticed is that the sequence of operations in the
>>> phone is as follows:
>>> - the phone is connected
>>> unknown trigger
>>> - the phone attempts a new random access
>>> - the random access succeeds and the phone gets a new c-RNTI from the
>>> eNB together with a new IP address
>>> - the eNB disconnects the old c-RNTI
>>> It looks to me that at this point the mobile phone is connected to the
>>> eNB on a TEID that mismatch the one it is using in the EPC.
>>> Is there a way to understand if a new random access procedure is
>>> perfomed by a terminal considered already connected to the eNB?
>>> Maybe I am just wrong.
>>>
>>> Looking forward to your interpretation.
>>> Best,
>>>
>>>
>>> Nicola Bui
>>> Senior Research Scientist
>>> College of Computer and Information Science
>>> 655E Interdisciplinary Science and Engineering Complex
>>> Boston, MA 02115
>>>
>>> On Fri, Oct 27, 2017 at 2:08 PM, Nicola Bui <n.bui at northeastern.edu>
>>> wrote:
>>>
>>>> Hi Ismael,
>>>>
>>>> attached you can find the log. To get the error I did the following:
>>>> - start the epc (OAI - hss, mme, spgw)
>>>> - start srsenb
>>>> - turn on the off
>>>> - some pings to 172.16.0.1 to check the connectivity
>>>> - speedtest (in the middle of the download test) the C-RNTI got
>>>> released
>>>> 13:54:16.034525 <0345%2025> [RRC ] Info    Disconnecting rnti=0x46.
>>>> Before this, in the log you can find that there is another RRC
>>>> connection request, which should not be there to the best of my knowledge.
>>>> After the disconnection the mobile phone continue using the new C-RNTI
>>>> obtained with the strange connection request, but, apparently, only the
>>>> uplink is working.
>>>>
>>>> Please, let me know should you need other tests and thank you for the
>>>> support.
>>>> Best regards,
>>>>
>>>>
>>>> Nicola Bui
>>>> Senior Research Scientist
>>>> College of Computer and Information Science
>>>> 655E Interdisciplinary Science and Engineering Complex
>>>> Boston, MA 02115
>>>>
>>>> On Fri, Oct 27, 2017 at 11:28 AM, Ismael Gomez <ismael.gomez@
>>>> softwareradiosystems.com> wrote:
>>>>
>>>>> Hi nicola, can you send the enb.log?
>>>>>
>>>>> El vie., 27 oct. 2017 3:52, Nicola Bui <n.bui at northeastern.edu>
>>>>> escribió:
>>>>>
>>>>>> Thanks Ishmael, Kewin,
>>>>>>
>>>>>> that's not my issue: the problem happens while the phone is active,
>>>>>> in particular when the last is high.
>>>>>> I already tried increasing the inactivity timer and the error count
>>>>>> in the configuration file.
>>>>>> The stranger thing is, as soon as the phone is disconnected (I
>>>>>> believe it is the enb starting the disconnection) it gets a new rnti and,
>>>>>> from the phone perspectives, the network is visible and connected. However,
>>>>>> nothing works anymore like the new rnti is not linked anymore to the proper
>>>>>> device in the epc.
>>>>>> Instead, if I toggle the network from the phone, everything is
>>>>>> resumed properly.
>>>>>> I cannot send a log right now but I'll try to generate one containing
>>>>>> the issue and send it to you.
>>>>>>
>>>>>> Best,
>>>>>>
>>>>>> Nicola
>>>>>>
>>>>>> On Oct 27, 2017 04:00, "Kewin Rausch" <krausch at fbk.eu> wrote:
>>>>>>
>>>>>>> Hi everyone,
>>>>>>>
>>>>>>> I had a similar issue (dunno if it's really the same), and I
>>>>>>> partially resolved it by following Ismael answer and increasing the
>>>>>>> inactivity timeout period (now I set it at 60 seconds).
>>>>>>> Basically If i leave the UE connected to 4G but I do not generate
>>>>>>> traffic (for about the time the inactivity timeout value), it get
>>>>>>> disconnected by the eNB.
>>>>>>>
>>>>>>> This is not happening while I'm connected to a commercial base
>>>>>>> station, which means that something nasty is happening, and maybe paging is
>>>>>>> not correctly handled.
>>>>>>>
>>>>>>> I've tried the configuration with a Nexus 5, and once it get
>>>>>>> disconnected I need to reset everything by switching on and off the
>>>>>>> Airplane mode.
>>>>>>>
>>>>>>> Cheers,
>>>>>>> Kewin
>>>>>>>
>>>>>>> On Fri, Oct 27, 2017 at 8:35 AM, Ismael Gomez <ismael.gomez@
>>>>>>> softwareradiosystems.com> wrote:
>>>>>>>
>>>>>>>> Hi nicola, can you send us the enb.log? It is normal behavior to
>>>>>>>> release the connection after inactivity. You can extend the timeout in the
>>>>>>>> enb.conf file, expert section.
>>>>>>>>
>>>>>>>> However the UE should reconnect when paging is received when you
>>>>>>>> ping it for instance. If you send me the log I can check it.
>>>>>>>>
>>>>>>>> Regards
>>>>>>>>
>>>>>>>> El jue., 26 oct. 2017 17:27, Nicola Bui <n.bui at northeastern.edu>
>>>>>>>> escribió:
>>>>>>>>
>>>>>>>>> Dear all,
>>>>>>>>>
>>>>>>>>> I am running srsenb using oai as EPC. My mobile phone (moto g5+)
>>>>>>>>> connects to the network and for a while behave normally (ping is ok,
>>>>>>>>> surfing is ok, speedtest is fine). However, after some time everything
>>>>>>>>> stops working even though the phone still has an IP address the enb says
>>>>>>>>> the UE is attached (c-RNTI assigned properly).
>>>>>>>>> Actually, in the enb log I can see the c-RNTI got released and a
>>>>>>>>> new one got assigned to the UE, but the new connection is not working
>>>>>>>>> anymore. The only way for recovering the connectivity is from the mobile
>>>>>>>>> toggling on and off the airplane mode.
>>>>>>>>> The only error message I can see is: Unhandled feature in RRC
>>>>>>>>> function: liblte_rrc_unpck_rrc_connection_setup_complete
>>>>>>>>> However this appears even when the connection has been properly
>>>>>>>>> setup.
>>>>>>>>>
>>>>>>>>> It will be great if I can get a more stable connection or if the
>>>>>>>>> connection can be automatically reestablished.
>>>>>>>>> Any suggestion on how to debug this?
>>>>>>>>>
>>>>>>>>> Thanks,
>>>>>>>>> Nicola Bui
>>>>>>>>> Senior Research Scientist
>>>>>>>>> College of Computer and Information Science
>>>>>>>>> 655E Interdisciplinary Science and Engineering Complex
>>>>>>>>> Boston, MA 02115
>>>>>>>>> _______________________________________________
>>>>>>>>> srslte-users mailing list
>>>>>>>>> srslte-users at lists.softwareradiosystems.com
>>>>>>>>> http://www.softwareradiosystems.com/mailman/listinfo/srslte-users
>>>>>>>>>
>>>>>>>>
>>>>>>>> _______________________________________________
>>>>>>>> srslte-users mailing list
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>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>
>>
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