https://osmocom.org/https://osmocom.org/favicon.ico?16647414092018-03-14T13:09:09ZOpen Source Mobile CommunicationsOsmoBTS - Bug #3055: osmo-bts-trx: slow TA loop feedbackhttps://osmocom.org/issues/3055?journal_id=82262018-03-14T13:09:09Zlaforge
<ul><li><strong>Related to</strong> <i><a class="issue tracker-2 status-3 priority-2 priority-default closed" href="/issues/1851">Feature #1851</a>: generalize power control and TA loop code</i> added</li></ul> OsmoBTS - Bug #3055: osmo-bts-trx: slow TA loop feedbackhttps://osmocom.org/issues/3055?journal_id=83212018-03-17T23:37:27Zlaforge
<ul><li><strong>Assignee</strong> set to <i>4368</i></li></ul> OsmoBTS - Bug #3055: osmo-bts-trx: slow TA loop feedbackhttps://osmocom.org/issues/3055?journal_id=84472018-03-22T17:28:32Zfixeria
<ul><li><strong>Related to</strong> <i><a class="issue tracker-1 status-3 priority-3 priority-high3 closed" href="/issues/2988">Bug #2988</a>: unexpected bit errors when using trxcon and osmo-bts-trx</i> added</li></ul> OsmoBTS - Bug #3055: osmo-bts-trx: slow TA loop feedbackhttps://osmocom.org/issues/3055?journal_id=97742018-06-06T21:52:42Zlaforge
<ul></ul><p>We now have a wiki page about timing advance: <a class="wiki-page" href="https://osmocom.org/projects/osmobts/wiki/Timing_Advance">Timing_Advance</a></p> OsmoBTS - Bug #3055: osmo-bts-trx: slow TA loop feedbackhttps://osmocom.org/issues/3055?journal_id=122962018-10-20T19:35:31Zlaforge
<ul><li><strong>Assignee</strong> changed from <i>4368</i> to <i>tnt</i></li></ul> OsmoBTS - Bug #3055: osmo-bts-trx: slow TA loop feedbackhttps://osmocom.org/issues/3055?journal_id=131012019-01-21T15:36:45Ztnt
<ul></ul><p>Yes, it's slow. But OTOH it can cope with at least 1 TA value every 2 second, so that's a MS moving at ~ 1000 km/h. The way it's implemented now, it's basically heavily dampened which means it should also be very stable.</p>
<p>An alternative is to make the step proportional to the toa difference, basically reducing the time to adapt.</p>
<p>Instead of doing +1 we'd do + (toa * alpha) alpha being the damped factor. The closer alpha is, the faster it's going to react but also the more it can oscillate in case of measurement noise.</p>
<p>Thoughts ? Is this really an issue ?</p> OsmoBTS - Bug #3055: osmo-bts-trx: slow TA loop feedbackhttps://osmocom.org/issues/3055?journal_id=131052019-01-21T16:58:24Zfixeria
<ul><li><strong>Priority</strong> changed from <i>Normal</i> to <i>Low</i></li></ul><blockquote>
<p>Yes, it's slow. But OTOH it can cope with at least 1 TA value every 2 second, so that's a MS moving at ~ 1000 km/h.</p>
</blockquote>
<p>Hmm, you're right. GSM TS 05.10 says: "The control loop for the timing advance shall be implemented in such a way that it will cope with MSs moving at a speed up to 500 km/h", so the current implementation is compliant.</p>
<blockquote>
<p>An alternative is to make the step proportional to the toa difference, basically reducing the time to adapt.<br />Thoughts ? Is this really an issue ?</p>
</blockquote>
<p>Are there any other cases when the TA value rapidly changes and we need to react quickly?<br />If no, feel free to close this issue. Changing priority to low for now.</p> OsmoBTS - Bug #3055: osmo-bts-trx: slow TA loop feedbackhttps://osmocom.org/issues/3055?journal_id=131102019-01-22T15:50:07Zlaforge
<ul></ul><p>Hi Sylvain,</p>
<p>On Mon, Jan 21, 2019 at 03:36:46PM +0000, tnt [REDMINE] wrote:</p>
<blockquote>
<p>Yes, it's slow. But OTOH it can cope with at least 1 TA value every 2 second, so that's a MS moving at ~ 1000 km/h. The way it's implemented now, it's basically heavily dampened which means it should also be very stable.</p>
</blockquote>
<p>Indeed, you're making a very valid point. I don't think we need to react too quickly to large changes,<br />because something fishy is going on in such cases.</p>
<blockquote>
<p>Thoughts ? Is this really an issue ?</p>
</blockquote>
<p>I wouldn't think so.</p> OsmoBTS - Bug #3055: osmo-bts-trx: slow TA loop feedbackhttps://osmocom.org/issues/3055?journal_id=131122019-01-23T04:12:25Zfixeria
<ul><li><strong>Status</strong> changed from <i>New</i> to <i>Closed</i></li></ul><p>Ok, closing. Thank you Sylvain!</p>