Possible to control the radio strength of a nanoBTS?

historical

On Wed, Jun 03, 2009 at 10:40:18PM +0200, Nordin Bouchtaoui wrote:
> Well I guess you're right. I modified the source as suggested and tried it
> out. But there was no difference.
> 
> The reason I want to boost up its transmitpower, is because I wanted to test
> the handover. 

There is certainly no way to 'boost' the power from the nanoBTS, since it
is specified to something like 250mW max output power.  The BS-11 has 3W
max output.

> Even when I switch off and on, while I'm just a meter away of our bts, my
> mobile somehow keeps registering to the real provider (I tested by simply
> calling someone).

That's quite obvious if you understand the details of the cell selection
algorithm.  If you've been registered to an actual cell of the operator before,
then that ARFCN/LAC is stored on the SIM card even when you shut off the phone.

So the phone will first try to register to that cell again before scanning the
entire band.

> Another interesting thing is, if I simulate a total different provider,
> which doesn't exist here, I can easely find our bts, with manual search.

of course.

> Also the MS seems to have its own database of all the country codes,
> networkcodes and its belonging providernames. I thought the BSC sends these
> information to the MS and the MS checks it with SIM data. (But that;s
> off-topic).

The BTS only sends numeric ID's in the BCCH.  Only _after_ you register, the
BTS (well, actually the BSC) sends a MM INFO message with the string-name of
the network.

So yes, typically the translation of mcc/mnc happens in a table on the SIM
card, and if that fails in a table that is included at compile time into the
GSM firmware of the handset.

-- 
- Harald Welte <laforge at gnumonks.org>           http://laforge.gnumonks.org/
============================================================================
"Privacy in residential applications is a desirable marketing option."
                                                  (ETSI EN 300 175-7 Ch. A6)
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