[srslte-users] Issue when receiving long SIB by UE

[Francisco Paisana]

Hi again,

I am not really sure what you are trying to achieve, but looking at the
logs I was able to make the following observations:
- the UE sets the receive window for the SIB3 at win_start=1140 (ue logs):

> 14:29:13.531544 [RRC ] [I] Proc "SI Acquire" - Starting SI Acquisition
> procedure for posSIBs
> 14:29:13.531548 [MAC ] [I] [  970] SCHED: Searching for DL dci for SI-RNTI
> window_st=1140, window_len=20
> 14:29:13.531551 [RRC ] [I] Proc "SI Acquire" - Instructed MAC to search
> for SIB3, win_start=1140, win_len=20, period=16, sched_index=1
>

- the eNB sends the SIB of interest at tti=1155 (enb logs):

> 14:29:13.708292 [MAC ] [D] [ 1155] SCHED: SIB3, rbgs=(0,1), dci=(2,0),
> rv=2, len=223, period=8, mcs=24
>

- the UE detects the SIB and tries to decode it. Unfortunately, the
decoding fails - see ack=KO (ue logs):

> 14:29:13.714318 [PHY0] [D] [ 1159] PDCCH looking for rnti=0xffff
> 14:29:13.714375 [PHY0] [I] [ 1159] PDCCH: cc=0, f=1A, cce= 0, L=3,
> riv=300, pid=0, mcs={24}, ndi={0}, tpc_pucch=0, snr=37.7 dB
> 14:29:13.714388 [MAC ] [D] [ 1159] Set HARQ for retransmission
> 14:29:13.714605 [PHY0] [I] [ 1159] PDSCH: cc=0, rnti=0xffff, nof_prb=4,
> nof_re=600, tbs={225}, mod={2}, rv={2}, crc={KO}, it=4.0, snr=37.7 dB
> 14:29:13.714617 [MAC ] [I] [ 1159] DL 0 (TB 0):  reTX  tbs=225, rv=2,
> ack=KO, ndi=0
>

The eNB tbs=223 (Transport Block Size) and the UE decoded tbs=225 do not
seem to match.

It looks to me that the set tbs=223 in the eNB is not valid and is causing
the mismatch. Can you try to pad it with 2 zeros, to see if it fixes the
problem?

Kind Regards,
Francisco


On Mon, Mar 1, 2021 at 3:12 PM Taillefer Simon <
simon.taillefer at telespazio.com> wrote:

> Hello Francisco Paisana,
>
>
>
> Please find attached the logs of the ENB and UE. I removed some lines in
> the UE logs because the files were too heavy.
>
>
>
> Please also note that the message causing the issue is the message
> containing the posSIBs and the assistance data. It is also called SIB3
> because it is the third SIB message sent to the UE (after the SIB1 and the
> message that contains all the other SIBs like SIB2, SIB3 and etc.).
>
>
>
> Thank you for your help,
>
>
>
> Simon Taillefer
>
>
>
> *De :* Francisco Paisana <francisco.paisana at softwareradiosystems.com>
> *Envoyé :* lundi 1 mars 2021 13:44
> *À :* Taillefer Simon <simon.taillefer at telespazio.com>
> *Cc :* srslte-users at lists.softwareradiosystems.com
> *Objet :* Re: [srslte-users] Issue when receiving long SIB by UE
>
>
>
> Hello Taillefer Simon,
>
>
>
> Can you share the logs of the eNB and UE?
>
>
> Kind Regards,
>
> Francisco
>
>
>
>
>
> On Sun, Feb 28, 2021 at 2:00 PM Taillefer Simon <
> simon.taillefer at telespazio.com> wrote:
>
> Hello srsLTE team,
>
>
>
> We are having trouble with the reception of a long SIB message by the UE.
>
>
>
> More precisely, the UE is not able to connect to the ENB because it
> timeouts if the SIB message with all other SIBs (SIB2, SIB3, …) created on
> the generate_sibs function in the srsenb/src/stack/rrc/rrc.cc file has a
> length of more than 173 bytes.
>
> The UE loops on the si_acquire_proc::init function in the
> *srsLTE/srsue/src/stack/rrc/rrc_procedures.cc.*
>
> The raised error are the following:
>
> -          [RRC ] [I] Proc "SI Acquire" - SI Acquire Retry Timeout for
> SIB2 from *srsLTE/srsue/src/stack/rrc/rrc_procedures.cc* file line 369.
>
> -          [RRC ] [E] Proc "SI Acquire" - Timeout while acquiring SIB2 from
> *srsLTE/srsue/src/stack/rrc/rrc_procedures.cc* file line 376
>
> -          [RRC ] [E] Proc "SI Acquire" - Failed to acquire SIB2 from
> *srsLTE/srsue/src/stack/rrc/rrc_procedures.cc* file line 320
>
>
>
> Do you know if there is a solution to receive longer messages to allow the
> UE to connect with the ENB?
>
>
>
> Thank you in advance for your help,
>
>
>
> *Simon Taillefer*
>
>
>
>
>
>
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