https://projects.osmocom.org/https://projects.osmocom.org/favicon.ico?16647414092018-07-27T20:24:04ZOpen Source Mobile CommunicationsOsmocomBB SDR PHY - Feature #3423: Receiver: hard-coded GSM 05.02 channel configurationhttps://projects.osmocom.org/issues/3423?journal_id=105072018-07-27T20:24:04Zptrkrysik
<ul></ul><p>Just a note that in my opinion we more need to be able to configure what<br />is configuration of burst types in given timeslot. We don't need to<br />inform it what exact logical channel types are bound to given timeslot.</p> OsmocomBB SDR PHY - Feature #3423: Receiver: hard-coded GSM 05.02 channel configurationhttps://projects.osmocom.org/issues/3423?journal_id=105102018-07-28T10:51:36Zfixeria
<ul></ul><p>Well, I think e.g. this 'FCCH+SCH+CCCH+BCCH' combination clearly defines<br />which types of bursts we would expect on a given timeslot...</p>
<p>This is already implemented in <a class="wiki-page" href="https://projects.osmocom.org/projects/osmotrx/wiki">OsmoTRX</a>, have a look:</p>
<p><a class="external" href="https://git.osmocom.org/osmo-trx/tree/Transceiver52M/Transceiver.h#n131">https://git.osmocom.org/osmo-trx/tree/Transceiver52M/Transceiver.h#n131</a><br /><a class="external" href="https://git.osmocom.org/osmo-trx/tree/Transceiver52M/Transceiver.cpp#n411">https://git.osmocom.org/osmo-trx/tree/Transceiver52M/Transceiver.cpp#n411</a></p>
<p>Also, trxcon is capable to send 'SETSLOT <TS> <TYPE>' command, which<br />AFAIR contains exactly a channel combination number...</p> OsmocomBB SDR PHY - Feature #3423: Receiver: hard-coded GSM 05.02 channel configurationhttps://projects.osmocom.org/issues/3423?journal_id=105112018-07-28T10:53:34Zfixeria
<ul></ul><p>For sure, we may also implement an advanced channel combination option, which<br />would allow to specify required burst types manually, e.g. 'sb,fb,nb'...</p> OsmocomBB SDR PHY - Feature #3423: Receiver: hard-coded GSM 05.02 channel configurationhttps://projects.osmocom.org/issues/3423?journal_id=105122018-07-28T11:04:45Zptrkrysik
<ul></ul><p>In my opinion all the receiver should care is if it should expect in a<br />given timeslot:<br />-normal burst<br />-normal burst or dummy burst,<br />-normal burst or nothing,<br />-FCCH,<br />-SCH.</p>
<p>We can use the combinations as a set of predefined configurations of<br />burst types, but I wouldn't limit the receiver to those.</p> OsmocomBB SDR PHY - Feature #3423: Receiver: hard-coded GSM 05.02 channel configurationhttps://projects.osmocom.org/issues/3423?journal_id=130962019-01-19T12:27:54Zfixeria
<ul><li><strong>Tracker</strong> changed from <i>Bug</i> to <i>Feature</i></li><li><strong>Status</strong> changed from <i>New</i> to <i>Stalled</i></li><li><strong>% Done</strong> changed from <i>0</i> to <i>20</i></li></ul><p>Initial work can be found in a separate branch: <a class="external" href="https://git.osmocom.org/gr-gsm/log/?h=fixeria/mf_config">https://git.osmocom.org/gr-gsm/log/?h=fixeria/mf_config</a></p>
<p>As it turns out, indicating a channel combination alone is not enough, because unlike the BTS, we don't<br />need to detect and demodulate bursts on all logical channels of a given timeslot configuration.<br />So, I am not sure if the current API is exactly what we need, it's too low level...</p>
<p>A possible solution is to define the most useful channel combinations from GSM 05.02 in Receiver,<br />either as it's done in trxcon and osmo-bts, or as it's done in the firmware of OsmocomBB:</p>
<p><a class="external" href="https://git.osmocom.org/osmocom-bb/tree/src/host/trxcon/sched_mframe.c">https://git.osmocom.org/osmocom-bb/tree/src/host/trxcon/sched_mframe.c</a><br /><a class="external" href="https://git.osmocom.org/osmocom-bb/tree/src/target/firmware/layer1/mframe_sched.c">https://git.osmocom.org/osmocom-bb/tree/src/target/firmware/layer1/mframe_sched.c</a></p>
<p>and introduce a new TRXC command, that will be used to activate or deactivate particular<br />logical channels, e.g.:</p>
<pre>
SETLCHAN <TS> <LCHAN> <STATE>
SETLCHAN 0 FCCH 1
SETLCHAN 0 SCH 1
SETLCHAN 0 CCCH 1
SETLCHAN 1 TRXC_SACCH4_3 0
SETLCHAN 1 TRXC_SDCCH4_3 1
</pre> OsmocomBB SDR PHY - Feature #3423: Receiver: hard-coded GSM 05.02 channel configurationhttps://projects.osmocom.org/issues/3423?journal_id=132412019-02-06T09:56:09Zptrkrysik
<ul></ul><p>Receiver is a low level creature and it will have low level interface.<br />The entity that controls it will know about combinations that make sense<br />in current GSM networks.</p>
<p>However current API needs extension with ability to tell when (for which<br />frame number) change should take place.</p> OsmocomBB SDR PHY - Feature #3423: Receiver: hard-coded GSM 05.02 channel configurationhttps://projects.osmocom.org/issues/3423?journal_id=132422019-02-06T10:00:43Zfixeria
<ul></ul><p>Ok, I am agree with you. There is no need to overload the Receiver with GSM 05.02 channel combinations, we can offload this to grgsm_trx or even to trxcon. Please see my initial (hackish and draft) attempt: <a class="external" href="https://git.osmocom.org/gr-gsm/log/?h=fixeria/mf_config">https://git.osmocom.org/gr-gsm/log/?h=fixeria/mf_config</a>.</p> OsmocomBB SDR PHY - Feature #3423: Receiver: hard-coded GSM 05.02 channel configurationhttps://projects.osmocom.org/issues/3423?journal_id=272582023-07-05T08:59:42Zptrkrysik
<ul><li><strong>Status</strong> changed from <i>Stalled</i> to <i>Closed</i></li></ul> OsmocomBB SDR PHY - Feature #3423: Receiver: hard-coded GSM 05.02 channel configurationhttps://projects.osmocom.org/issues/3423?journal_id=272922023-07-09T19:45:57Zfixeria
<ul><li><strong>Project</strong> changed from <i>gr-gsm</i> to <i>OsmocomBB SDR PHY</i></li><li><strong>Status</strong> changed from <i>Closed</i> to <i>Stalled</i></li><li><strong>Assignee</strong> deleted (<del><i>ptrkrysik</i></del>)</li></ul>