[srslte-users] Problem with decoding SIB2 using cell_measurement example

[ALEJANDRO BLANCO PIZARRO]

Hi Laura,

I do not completely understand your problem, but have you tried to decode
the SIB2 payload by http://www.marben-products.com/decoder-asn1-lte/?

Best!
Alejandro

2018-04-17 13:46 GMT+02:00 Laura Flueratoru <flueratorulaura at gmail.com>:

> Hi everyone,
>
> I am trying to decode SIB2 using the cell_measurement example. I have
> already decoded the information regarding the location of the SI
> messages from SIB1, and the periodicity of SIB2 should be RF8 (same as
> for SIB3) and the SI Window Length is 3.
>
> From this, I compute the subframe number, the periodicity and the
> offset according to 36.331 and try to search for the SIB2 in a loop as
> in the code snippet below:
>
>     if ((srslte_ue_sync_get_sfidx(&ue_sync) == si_loc[0].subframe) &&
>          (sfn % si_loc[0].period) == si_loc[0].mod_sfn) {
>         n = srslte_ue_dl_decode(&ue_dl, data, 0,
>                   sfn*10+srslte_ue_sync_get_sfidx(&ue_sync), acks);
>
> where:
>     - si_loc[0].subframe is SIB2's subframe number and has the value 0
>     - si_loc[0].period is SIB2's periodicity and has the value 8 (RF8)
>     - si_loc[0].mod_sfn is SIB2's offset and has the value 0
>
> It does find something at that location and an example payload is
> [40 48 a0 03 06 50 11 84 60 88 19 31 80 81 84 4c 23 61 23 18 00 00 63
> 9e 9d 00 00 00 00 00 00 00 65 2b 44 7c ef ]
> whereas the payload of SIB1 was
> [40 48 a0 03 06 50 11 84 60 88 19 31 80 81 84 4c 23 61 23 18 00 00 ]
>
> So I find it weird that the first part of the payload I get for SIB2
> would be exactly the same as for SIB1, so I think there's something
> wrong with the way I try to retrieve SIB2's data.
>
> Can you please tell me if there's something wrong with the way I
> search for the SI message? I tried to look in
> rrc::run_si_acquisition_procedure which seems to be computing the same
> location, but it seems to me that I'm doing almost the same thing here
> (minus specifying the window length in which to search for the SI
> message). Any help would be greatly appreciated. Thank you!
>
> Best regards,
> Laura
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