[srslte-users] srsenb disconnection problem

Sun Oct 29 04:02:33 UTC 2017

Also, make sure you have the TX and RX antennas in cross polarization, e.g.
one vertical and the other horizontal to avoid tx/rx cross-talk.

On Sat, 28 Oct 2017 at 16:52 Nicola Bui <n.bui at northeastern.edu> wrote:

> Sure, as soon I'm back in the lab on Monday
>
>
> Nicola
>
> On Oct 28, 2017 19:50, "Ismael Gomez" <
> ismael.gomez at softwareradiosystems.com> wrote:
>
>> Yes, could you send me the log for 50 PRB please?
>> thanks
>>
>> El sáb., 28 oct. 2017 15:30, Nicola Bui <n.bui at northeastern.edu>
>> escribió:
>>
>>> 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 at 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 at 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 at 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
>>>>>>>>>>>> _______________________________________________
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>>>>>>>>>>>> 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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