[srsran-users] RAR scheduling with mbsfn enabled release 2021_10

Mon Nov 15 18:17:37 UTC 2021

Hey Joe,

Nice work on the investigation!

Just to clarify, is this with the HEAD of the release or at the commit I
previously recommended.

In any case, the subframe allocation works as follows:

Subframes 1,2,3 6,7,8 are possible for mbms.

The number provided is a bit mask for these subframes, so 63 is 111 111
meaning all 6 possible subframes are scheduled for mbms.

33 would be 100001 so only 1 and 8 are scheduled for mbms.

It's likley that the RAR is in subframes 2,3 6 or 7 and thats why freeing
them up fixed the issues, try using a prach config that would result in the
RAR landing on a non mbms subframe ie 0, 4, 5 or 9 and try again with 63.

Regards,
Justin

On Mon, 15 Nov 2021, 18:25 J Giovatto, <jgiovatto at adjacentlink.com> wrote:

> Hi Folks,
>
> In our emulation environment I have seen some issue where the ue's can not
> connect. It is random but reproducible
>
> only in our emulation environment and not using zmq, though all of the
> config is essentially the same and in line with what is in the release,
> with 1 excpetion is we use 1 phythread.
>
> With the default sib mbsn subframe allocation default setting of 63, we
> will see illustrated below (log changes attached) where the enb will
> schedule
>
> what I believe is the RAR (rnti 0x2) on an mbsfn subframe.
>
> Below is a 2 ue connect snapshot ...
> 17:00:30.392495 [MAC    ] [I] [  901] SCHED: Added user rnti=0x46
>
> 17:00:30.392501 [MAC    ] [I] [  901] SCHED: rnti=0x46, new lcid
> configuration: [{lcid=0, mode=bi-dir, prio=1, lcg=0}]
> 17:00:30.392502 [MAC    ] [I] [  901] SCHED: Resetting rnti=0x46, cc=0
> HARQs and feedback state
> 17:00:30.392502 [MAC    ] [I] [  901] SCHED: rnti=0x46 PCell is now
> enb_cc_idx=0
> 17:00:30.392549 [RRC    ] [I] Setting RLF timer for rnti=0x46 to 4000ms
> 17:00:30.392559 [RLC    ] [I] Added LTE radio bearer with LCID 0 in
> Transparent Mode
> 17:00:30.392562 [RRC    ] [I] Added new user rnti=0x46
> 17:00:30.392563 [MAC    ] [I] [  902] SCHED: New PRACH tti=901,
> preamble=18, temp_crnti=0x46, ta_cmd=0, msg3_size=7
> 17:00:30.392563 [MAC    ] [I] [  902] RACH:  tti=901, cc=0, preamble=18,
> offset=0, temp_crnti=0x46
> 17:00:30.392570 [MAC    ] [I] [  902] rach_tprof: {mean, max, min}={343.2,
> 343, 343} usec, nof_samples=1
> 17:00:30.393051 [MAC    ] [I] [  903] SCHED: RAR, ra-rnti=2, rbgs=[0, 1),
> dci=(2,0), msg3 grants=[{c-rnti=0x46, rba=103, mcs=0}]
> 17:00:30.393068 [PHY    ] [I] [  904] PDCCH:enb_dl_put_dl_pdcch_i: cc=0,
> cellId 1, rnti 0x2, pdcch_seqnum 1338, type DL
> 17:00:30.393076 [PHY0   ] [I] [  903] PDCCH_DL: cc=0, f=1A, cce= 0, L=2,
> riv=100, pid=0, mcs={1}, ndi={0}, tpc_pucch=0, tti_tx_dl=907
> 17:00:30.393090 [PHY    ] [I] [  904] PDSCH:enb_dl_put_dl_pdsch_i: cc=0,
> cellId 1, rnti 0x2, pdsch_seqnum 1338
> 17:00:30.393093 [PHY0   ] [I] [  903] PDSCH: cc=0, rnti=0x2, nof_prb=3,
> nof_re=450, tbs={11}, mod={2}, rv={0}, tti_tx_dl=907
> 17:00:30.395050 [MAC    ] [I] [  905] SCHED: Msg3 tx rnti=0x46, cc=0,
> pid=1, dci=(0,0), prb=[3, 6), n_rtx=0, cfi=1, tbs=7, bsr=0 (0-7)
>
> ue-02/var/log/ue.log:17:00:30.392178 [PHY0   ] [W] [  902] work_dl_mbsfn
> calling decode_pdcch_dl
> ue-02/var/log/ue.log:17:00:30.393170 [PHY0   ] [W] [  903] work_dl_mbsfn
> calling decode_pdcch_dl
> ue-02/var/log/ue.log:17:00:30.396182 [PHY0   ] [W] [  906] work_dl_mbsfn
> calling decode_pdcch_dl
> ue-02/var/log/ue.log:17:00:30.397505 [PHY0   ] [W] [  907] work_dl_mbsfn
> calling decode_pdcch_dl
> ue-02/var/log/ue.log:17:00:30.398182 [PHY0   ] [W] [  908] work_dl_mbsfn
> calling decode_pdcch_dl
> ue-02/var/log/ue.log:17:00:30.401166 [PHY0   ] [W] [  911] work_dl_mbsfn
> calling decode_pdcch_dl
> ue-02/var/log/ue.log:17:00:30.402172 [PHY0   ] [W] [  912] work_dl_mbsfn
> calling decode_pdcch_dl
> ue-02/var/log/ue.log:17:00:30.403175 [PHY0   ] [W] [  913] work_dl_mbsfn
> calling decode_pdcch_dl
>
>
>
> 17:00:30.411465 [MAC    ] [I] [  921] SCHED: Added user rnti=0x47
> 17:00:30.411471 [MAC    ] [I] [  921] SCHED: rnti=0x47, new lcid
> configuration: [{lcid=0, mode=bi-dir, prio=1, lcg=0}]
> 17:00:30.411472 [MAC    ] [I] [  921] SCHED: Resetting rnti=0x47, cc=0
> HARQs and feedback state
> 17:00:30.411472 [MAC    ] [I] [  921] SCHED: rnti=0x47 PCell is now
> enb_cc_idx=0
> 17:00:30.411496 [RRC    ] [I] Setting RLF timer for rnti=0x47 to 4000ms
> 17:00:30.411505 [RLC    ] [I] Added LTE radio bearer with LCID 0 in
> Transparent Mode
> 17:00:30.411508 [RRC    ] [I] Added new user rnti=0x47
> 17:00:30.411509 [MAC    ] [I] [  921] SCHED: New PRACH tti=921,
> preamble=21, temp_crnti=0x47, ta_cmd=0, msg3_size=7
> 17:00:30.411509 [MAC    ] [I] [  921] RACH:  tti=921, cc=0, preamble=21,
> offset=0, temp_crnti=0x47
> 17:00:30.411514 [MAC    ] [I] [  921] rach_tprof: {mean, max, min}={282.2,
> 343, 221} usec, nof_samples=2
> 17:00:30.412053 [MAC    ] [I] [  922] SCHED: RAR, ra-rnti=2, rbgs=[0, 1),
> dci=(2,0), msg3 grants=[{c-rnti=0x47, rba=103, mcs=0}]
> 17:00:30.412072 [PHY    ] [I] [  923] PDCCH:enb_dl_put_dl_pdcch_i: cc=0,
> cellId 1, rnti 0x2, pdcch_seqnum 1341, type DL
> 17:00:30.412076 [PHY0   ] [I] [  922] PDCCH_DL: cc=0, f=1A, cce= 0, L=2,
> riv=100, pid=0, mcs={1}, ndi={0}, tpc_pucch=0, tti_tx_dl=926
> 17:00:30.412086 [PHY    ] [I] [  923] PDSCH:enb_dl_put_dl_pdsch_i: cc=0,
> cellId 1, rnti 0x2, pdsch_seqnum 1340
> 17:00:30.412088 [PHY0   ] [I] [  922] PDSCH: cc=0, rnti=0x2, nof_prb=3,
> nof_re=450, tbs={11}, mod={2}, rv={0}, tti_tx_dl=926
> 17:00:30.414046 [MAC    ] [I] [  924] SCHED: Msg3 tx rnti=0x47, cc=0,
> pid=4, dci=(0,0), prb=[3, 6), n_rtx=0, cfi=1, tbs=7, bsr=0 (0-7)
>
>
> ue-02/var/log/ue.log:17:00:30.408188 [PHY0   ] [W] [  918] work_dl_mbsfn
> calling decode_pdcch_dl
> ue-02/var/log/ue.log:17:00:30.411181 [PHY0   ] [W] [  921] work_dl_mbsfn
> calling decode_pdcch_dl
> ue-02/var/log/ue.log:17:00:30.412181 [PHY0   ] [W] [  922] work_dl_mbsfn
> calling decode_pdcch_dl
> ue-02/var/log/ue.log:17:00:30.413166 [PHY0   ] [W] [  923] work_dl_mbsfn
> calling decode_pdcch_dl
> ue-02/var/log/ue.log:17:00:30.416494 [PHY0   ] [W] [  926] work_dl_mbsfn
> calling decode_pdcch_dl
> ue-02/var/log/ue.log:17:00:30.417181 [PHY0   ] [W] [  927] work_dl_mbsfn
> calling decode_pdcch_dl
> ue-02/var/log/ue.log:17:00:30.418170 [PHY0   ] [W] [  928] work_dl_mbsfn
> calling decode_pdcch_dl
> ue-02/var/log/ue.log:17:00:30.421175 [PHY0   ] [W] [  931] work_dl_mbsfn
> calling decode_pdcch_dl
>
> If I change the subframe allocation to say (33) the problem goes away as
> far as I can tell.
>
> Can you guide to where the decision of the subframe is done and/or provide
> some suggestions ?
>
> Thanks
>
> Joe
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