https://osmocom.org/https://osmocom.org/favicon.ico?16647414092021-07-12T18:13:31ZOpen Source Mobile CommunicationsOsmoMSC - Bug #5197: msc_i Unimplemented msg type: HANDOVER PERFORMEDhttps://osmocom.org/issues/5197?journal_id=223892021-07-12T18:13:31Zneelsnhofmeyr@sysmocom.de
<ul></ul><p>If the BSC decides to handover within the BSS for improved reception, it does<br />the entire handover procedure on its own, and when that succeeded tells the MSC<br />about a possible change in LAC and codec.</p>
<p>So apparently osmo-msc so far doesn't care about that.</p>
<p>However I remember that we had patches related to storing the correct LAC in<br />the VLR, so in that way it may be good to actually decode the HANDOVER<br />PERFORMED, store the new LAC.</p>
<p>...and forward the LAC change to the HLR? Oh wait, checking GSUP and the HLR,<br />we apparently do not store the LAC in the HLR at all. Where did I get that<br />from?</p>
<p>So only update the serving cell in the VLR then, i.e. vlr_subscr->cgi from the<br />received struct gsm0808_handover_performed->cell_id.</p>
<p>We need a decoder of this message in libosmocore/src/gsm/gsm0808.c, so far we<br />only have the encoder (gsm0808_create_handover_performed()).</p>
<p>Possibly the BSC could also signal a codec change; theoretically we might need<br />to tell the MGW or MNCC about that? Could also be that it must be one of the<br />permitted codecs and only the RTP payload number changes in the RTP stream --<br />but for that we'd have to put all possible codecs in the MGCP which we don't.<br />We are still miles away from using that info properly, first step there would<br />be to merge these long standing osmo-msc codec patches (that code bomb that<br />negotiates SDP over MNCC and properly overlays all codec limitations from MS,<br />BSC, CN and remote call leg).</p> OsmoMSC - Bug #5197: msc_i Unimplemented msg type: HANDOVER PERFORMEDhttps://osmocom.org/issues/5197?journal_id=247172022-08-23T16:05:35Zneelsnhofmeyr@sysmocom.de
<ul></ul><p>quick update, looking at gsm0808.h, the situation is still unchanged.<br />osmo-msc does still not care about Handover Performed.</p>