Hello, I'm currently working on a proof of concept for a foreign customer. We have a Fairwaves UmTRX board and we would like to send Cell Broadcast message (SMS-CB). I have a full working osmocom chain (trx, bts-trx, bsc, stp, msc, hlr) that woks fine for SMS sending by example.
I have made a fix in rsl.c because all SMSCB commands where rejected (see at bottom of this message).
I have dig into the code and found the place where the SMS CB are queued (rsl.c : bts_process_smscb_cmd) and the code to extract them as MAC blocks (rsl.c : bts_cbch_get).
I have also found the handler of the scheduler (scheduler_trx.c : tx_data_fn) where to put the block data.
I have read articles about the superframe mechanism but I do not figure out how to advertise the CBCH functionality on the BCCH, nor how to adapt the scheduler to enable the CB channel.
Is it someone also interrested in this and/or working on the Bug 1617? Or is it someone that can me give a track to start the implementation?
Have a nice day, Antony
----------------------------------------------------------------------------------------------------------- Fix in rsl.c : ----------------------------------------------------------------------------------------------------------- replaced : if (chan_nr_is_dchan(cch->chan_nr)) return rsl_reject_unknown_lchan(msg);
msg->lchan = lchan_lookup(trx, cch->chan_nr, "RSL rx CCHAN: "); if (!msg->lchan) { LOGP(DRSL, LOGL_ERROR, "Rx RSL %s for unknown lchan\n", rsl_msg_name(cch->c.msg_type)); return rsl_reject_unknown_lchan(msg); }
----------------------------------------------------------------------------------------------------------- by: if (chan_nr_is_dchan(cch->chan_nr)) { printf("Message NOT for DCHAN\n"); //return rsl_reject_unknown_lchan(msg); } else { printf("Message for DCHAN\n");
// Only check channel validity if it is a dedicated channel call. msg->lchan = lchan_lookup(trx, cch->chan_nr, "RSL rx CCHAN: "); if (!msg->lchan) { LOGP(DRSL, LOGL_ERROR, "Rx RSL %s for unknown lchan\n", rsl_msg_name(cch->c.msg_type)); return rsl_reject_unknown_lchan(msg); } }
Hi Antony,
On Fri, Apr 06, 2018 at 10:36:06AM +0200, Antony Lemmens wrote:
I have read articles about the superframe mechanism but I do not figure out how to advertise the CBCH functionality on the BCCH,
The Osmocom stack should take care of this "automatically" if the osmo-bts-trx low-level code gets the required support.
As you may have seen, CBCH operation is already supported with several other BTS back-ends inside osmo-bts. Unfortunately, for osmo-bts-trx nobody has been contributing the related code so far.
nor how to adapt the scheduler to enable the CB channel.
This boils down to the tables in osmo-bts/src/scheduler_mframe.c where you can e.g. find "static const struct trx_sched_frame frame_bcch[51]" which defines the 51-multiframe for the non-combined BCCH and "static const struct trx_sched_frame frame_bcch_sdcch4[102]" for the combined BCCH, as well as "static const struct trx_sched_frame frame_sdcch8"
AFAIR, the BCCH can be on a combined BCCH or on a SDCCH/8. You would have to create copies of "frame_bcch_sdcch4" and "frame_sdcch8" and edit those copies to confirm with the way how the respective multiframe is specified when CBCH is enabled. As far as I remember from memory, it's always the second sub-channel that's replaced with CBCH instead of SDCCH. See the related specs, I think mostly 3GPP TS 45.002
Is it someone also interrested in this and/or working on the Bug 1617?
I'm interested but seriously have no time to work on this. At sysmocm we could work on it as a development project under contract, but we also have quite a backlog so it might be best if somebody else works on this.
Or is it someone that can me give a track to start the implementation?
My notes above should help with implementing it.
Hello Harald, thanks for you quick answer, I'll take a look on that.
Have a nice day, Antony
On Fri, Apr 6, 2018 at 10:59 AM, Harald Welte laforge@gnumonks.org wrote:
Hi Antony,
On Fri, Apr 06, 2018 at 10:36:06AM +0200, Antony Lemmens wrote:
I have read articles about the superframe mechanism but I do not figure
out
how to advertise the CBCH functionality on the BCCH,
The Osmocom stack should take care of this "automatically" if the osmo-bts-trx low-level code gets the required support.
As you may have seen, CBCH operation is already supported with several other BTS back-ends inside osmo-bts. Unfortunately, for osmo-bts-trx nobody has been contributing the related code so far.
nor how to adapt the scheduler to enable the CB channel.
This boils down to the tables in osmo-bts/src/scheduler_mframe.c where you can e.g. find "static const struct trx_sched_frame frame_bcch[51]" which defines the 51-multiframe for the non-combined BCCH and "static const struct trx_sched_frame frame_bcch_sdcch4[102]" for the combined BCCH, as well as "static const struct trx_sched_frame frame_sdcch8"
AFAIR, the BCCH can be on a combined BCCH or on a SDCCH/8. You would have to create copies of "frame_bcch_sdcch4" and "frame_sdcch8" and edit those copies to confirm with the way how the respective multiframe is specified when CBCH is enabled. As far as I remember from memory, it's always the second sub-channel that's replaced with CBCH instead of SDCCH. See the related specs, I think mostly 3GPP TS 45.002
Is it someone also interrested in this and/or working on the Bug 1617?
I'm interested but seriously have no time to work on this. At sysmocm we could work on it as a development project under contract, but we also have quite a backlog so it might be best if somebody else works on this.
Or is it someone that can me give a track to start the implementation?
My notes above should help with implementing it.
--
- Harald Welte laforge@gnumonks.org
http://laforge.gnumonks.org/
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Antony Lemmens -
Harald Welte