Openbsc support for new BTS

[Harald Welte]

Hi Jason,

On Tue, Jan 21, 2014 at 12:51:41PM +0000, Jason DSouza wrote:
> > which means that you get lots of false positives from the PHY.  Is
> > that the case?
> 
> I do not think they are false positives from the phy, neither I think
> our CRC is weak. Those are mainly the rach from real commercial phones
> around.

I am not referring to your implementation, but to the general effects /
short-comings / implications of the GSM specification.  As far as I
understand, you typically have lots of false positives as the CRC
_inside_ the RACH burst is so weak, that applying it to random noies
will still give you considerable number of hits.

But yes, if you actually operate with an antenna during R&D, then you
will likely see real RACH bursts of commercial phones.

> > In osmo-bts code itself, you can set a threshold in terms of RxLevel
> > or C/I and drop all requests below a certain level or C/I
> 
> I need to check the support for those messages in our L1.

The L1 just has to report RxLevel and C/I to osmo-bts, the rest is done
in osmo-bts.

> > In the system information, you can play with paramters such as
> > Rx-Access-Level-Min.
> 
> The parameter rxlev access min <0-63> in the openbsc config takes care
> of this?  But again, this is measurement information I guess and need
> to be supported by the phy.

This is a standard GSM radio parameter that will change behavior of the
MS.  No support required in your PHY.

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