cell re-selection

Harald Welte laforge at gnumonks.org
Sat Mar 5 06:49:38 UTC 2016


Hi Asghar,

On Mon, Feb 29, 2016 at 12:16:59AM -0700, Patrick wrote:
> I am working on the implementation of call handover (in dedicated mode) to
> the osmocom-bb code. Any progress from your side or any insights that you
> feel are necessary for this implementation would be highly appreciated.

I think we had this didscussion several times in the past.  Maybe it was
at physical meetings of developers only and not on the list yet, sorry.

The necessary code on the Layer2/3 side should all be implemented.  The
remainder is the wokr required in the layer 1 on the phone, where the
problem of synchronizing to the neighbor cells has to be solved.

The various BTSs all have their own clock, and they are not synchronized
to one another.  In order to do hand-over, the MS involved needs to send
regular measurement reports of neighbor cells.  In order to do so, it
needs to switch to the neighbor cell ARFCN and perform both a power
measurement as well as a Sync Burst detection to obtain the BSIC.

So the L1 needs to
* be able to maintain synchronization parameters not only for the
  serving cell but also for neighbor cells
* be able to switch + re-sync to a neighbor cell in the idle slot of the
  26-multiframe.  Iterate over all neighbor cells in successive idle
  slots.
* provide rx level + BSIC readings for those neighbors to l2/l3 on
  the PC

Regards,
	Harald
-- 
- Harald Welte <laforge at gnumonks.org>           http://laforge.gnumonks.org/
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