Cellular Network Infrastructure » Radio Access Network » OsmoBSC

I tested osmo-bsc:

• apply a patch that does TCH/F <-> TCH/H handovers regardless of codec ( http://git.osmocom.org/osmo-bsc/log/?h=neels/hodec2 )
• configuration of two TCH/F and a couple TCH/H lchans, and handover algorithm 2.
• establish voice call on the two TCH/F
• then set 'handover2 min-free-slots tch/f 1'
• the congestion check moves the first TCH/F to a TCH/H lchan.

What should happen?
Marking 'ok:' for things that already work with current osmo-bsc, 'TODO:' for things that don't.

RSL:

• ok: Establish new lchan with HR1 codec
• ok: Perform handover dance

MGCP:

• ok: redirect the BTS-facing endpoint conn to the new lchan's RTP port
• ok: configure the BTS-facing endpoint conn to indicate the change to HR1 codec
• TODO: since osmo-mgw does not transcode, also indicate the codec change on the MSC-facing endpoint conn

BSSAP:

• TODO: After handover, a Handover Performed message should indicate the codec change.
  • the Handover Performed message is sent, but it still indicates FR1 codec being used.

MSC, out of scope for this issue:

• the MSC's MGW endpoint conns should be reconfigured to match the codec change.
• mismatching codecs are only possible for external MNCC, i.e. using a SIP PBX behind osmo-msc.
• the MNCC socket and SIP should be notified of the codec change (by updated SDP info).

attaching patch as file since above link is to a branch which might get lost at some point