Some more thoughts on that old topic:
A custom protocol seems to make more and more sense. Neither original
RSL nor 08.08 seem to be a close match.
Some more specification of the original protocol idea:
On Wed, Apr 14, 2010 at 11:48:22PM +0200, Harald Welte wrote:
> * ESTABLISH REQUEST -- app requests a channel be established to MS (by IMSI)
Parameters:
* mobile identity (tmsi/imsi) (can re-use 04.08 mobile identity IE)
* channel type (sdcch/tch) (can reuse RSL information element)
* which parts of the protocol shall openbsc handle (RR/MM/CC)
* unique reference identifying this 'call/radio channel'
> * ESTABLISH CONFIRM -- network confirms a channel has been established
(confirmation that the radio channel has been established)
Parameters:
* unique reference identifying this call/radio channel
* exact arfcn/timeslot/sub-slot that was established
(can be RSL or 04.08 channel description)
> * ESTABLISH INDICATION -- network tells app connection was made by MS
(confirmation that a LAPDm connection was established)
Parameters:
* unique reference identifying this call/radio channel
* SAPI (RSL Link ID)
> * [UNIT] DATA REQUEST -- app requests data to be sent to MS
> * [UNIT] DATA INDICATION -- network indicates data was received from MS
Parameters:
* unique reference identifying this call/radio channel
* SAPI (RSL Link ID)
> * ERROR INDICATION -- network tells app something went wrong
Parameters:
* unique reference identifying this call/radio channel
* error code / reason
> * RELEASE REQUEST -- app asks network to release channel
Parameters:
* unique reference identifying this call/radio channel
> * RELEASE CONFIRM -- net tells app that channel was released (as rqd)
Parameters:
* unique reference identifying this call/radio channel
> * RELEASE INDICATION -- net tells app that channel was released (by MS)
Parameters:
* unique reference identifying this call/radio channel
--
- Harald Welte <[email protected]> http://laforge.gnumonks.org/
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