nanoBTS multi-TRX setup

historical

On Wed, Apr 13, 2011 at 01:10:54PM +0200, Konrad Meier wrote:
> Hi all,
> 
> I was just reading the wiki page about the nanoBTS multi-TRX setup.
> Two things are not clear to me.
> 
> 1. What is the purpose of the "RF cable"?

that is unclear, we don't have documentation on it..

The TIB (timing interface bus) cable is obvious: to synchronize timing.
The OML gets routed via the ethernet ports.  So I don't really know why
they need an extra RF cable...

> Is the TX port of the master BTS looped through the second BTS? Or
> hase every nanoBTS his own TRX/RX?

NO !!! my god, you don't want to kill your BTSs.  Tx / Rx is separate
like before.

> I am asking because I would like to use a nanoBTS-Booster with the
> multi-TRX setup and therefore require a combined RF signal.

the best idea is to use independent boosters.  If you want to run two
TRX nanoBTS throguh one amplifier, you need high-grade RF combiner, make
sure the amplifier doesn't produce intermodulation, etc.  Definitely not
something you want to be doing without somebody who has a clue about proper
RF setups at those frequencies.

> 2. The example example "openbsc.cfg" configures the trx 1 as follows:
> 
>   timeslot 0
>     phys_chan_config CCCH+SDCCH4
>   timeslot 1
>     phys_chan_config SDCCH8
> 
> Is this really needed? My first idea was to configure the second trx
> to TCH/F only.

That depends on your network requirements, you can of course have all TCH/F.

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