[srslte-users] srsUE does not receive posSIBs

[Taillefer Simon]

Hello srsLTE team,

We want to send positioning information to the UE through the LTE network emulated with srsLTE. This type of information is part of the 3GPP Release 15 which is not yet implemented in this software.

Thus, the idea is to send posSIBs (System Information Block Pos) from the ENB to the UE. We have already added all the necessary functions to add the posSIB types in the SIB1 as it is done for the other SIBs. Then we create the posSIB structure, fill it and pack it in the SI message after the SIB2 that is sent to the UE.
See in the enb.log file attached an example of the SIB1 and posSIB structures at the beginning of the file.

Then, regarding the transmission, each of the three structures are periodically sent to the UE. As shown in the enb_pcap.png screenshot and in the enb.log file, the posSIB structure (called SIB3 with a size of 28 bytes) is correctly sent exactly like the SIB1 and SIB2 (and others SIBs packed in SIB2).

Example of the posSIBs correctly sent:
11:16:24.940564 [PHY0] [D] [   24] Setting TTI=25, tx_mutex=2, tx_time=2:0.224425 to worker 1
11:16:24.940614 [PHY1] [D] [   25] Worker 1 running
11:16:24.940660 [MAC ] [D] [   25] ra_tbs=144/224, tbs_bytes=28, tbs=224, mcs=5
11:16:24.940664 [MAC ] [D] [   25] SCHED: SIB3, rbgs=(0,2), dci=(2,0), rv=0, len=28, period=8, mcs=5
11:16:24.940709 [PHY1] [D] [   25] Sending to radio

The issue is that this 28 bytes from the posSIBs message are never received in the UE (see the ue.log file and ue_pcap.png screenshot). However, the SIB1 is correctly received with the posSIB types inside such as the SIB2. We complete the parse_pdu_bcch_dlsch function to be able to decode the posSIBs from this channel and the UE knows that posSIBs are awaited (see example below). We also tried to check all the messages, their size and all the bytes received in the PHY and MAC layers by adding prints and logs but the posSIBs completely disappear. We though it is not an issue caused by the size of the messages (like SI message length or periodicity) because we tried different configurations.

Example of posSIB types decoded from SIB1:
09:56:52.612265 [RRC ] [I] SIB1 received, CellID=2817, si_window=20, sib2_period=16, posSIB_period=16
09:56:52.612268 [RRC ] [D] SIB scheduling info, sib_type=3, si_periodicity=16
09:56:52.612270 [RRC ] [D] SIB scheduling info, sib_type=7, si_periodicity=16
09:56:52.612273 [RRC ] [D] posSIB scheduling info, posSibType1-5, si_periodicity=16
09:56:52.612276 [RRC ] [D] posSIB scheduling info, posSibType2-3, si_periodicity=16

So, the questions are: Do you have any idea of what could go wrong to do not receive the posSIB message (even the bytes) on the UE side? Or if there are any blocking points that could remove our message from the lower layers ? Or whatever we missed to do ?

Thank you for your help,

Kind regards,

Simon Taillefer





-WARNING: This message contains confidential and/or proprietary information which may be subject to privilege or immunity and which is intended for the use of its addressee only.
Should you receive this message in error, you are kindly requested to inform the sender and to definitively remove it from any paper or electronic format.
Any other use of this e-mail is strictly forbidden. Thank you in advance for your cooperation.

Please consider the environment before printing this e-mail.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.srsran.com/pipermail/srsran-users/attachments/20200819/c819724f/attachment.htm>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: enb.log
Type: application/octet-stream
Size: 1204540 bytes
Desc: enb.log
URL: <https://lists.srsran.com/pipermail/srsran-users/attachments/20200819/c819724f/attachment.obj>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: enb_pcap.png
Type: image/png
Size: 233772 bytes
Desc: enb_pcap.png
URL: <https://lists.srsran.com/pipermail/srsran-users/attachments/20200819/c819724f/attachment.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: ue.log
Type: application/octet-stream
Size: 5268023 bytes
Desc: ue.log
URL: <https://lists.srsran.com/pipermail/srsran-users/attachments/20200819/c819724f/attachment-0001.obj>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: ue_pcap.png
Type: image/png
Size: 222236 bytes
Desc: ue_pcap.png
URL: <https://lists.srsran.com/pipermail/srsran-users/attachments/20200819/c819724f/attachment-0001.png>