Testing protocol stack with OsmocomBB (cheap way)

Sylvain Munaut 246tnt at gmail.com
Sun May 29 23:22:44 UTC 2011


> Now, I understand that osmocon can be used to load layer1 into phones
> RAM, so that this code turns on Calypso and communicate with DSP with
> AT commands.

... there is no AT commands anywhere ...

> What I am most interested in how do we insert pacgaes on the other
> side of the stack, i.e. via telephone air interface (packets that will
> traverse through Rita, Iota, Calypso down to stdout of host). From
> what I understand we need some kind of BTS, and I can see that GNU
> Radio is used for this purpose. But for this, as I understand USPRP

If you want to inject packet towards a phone, yes you need your own BTS.
OpenBTS using a USRP is one possibility.

> (http://en.wikipedia.org/wiki/Universal_Software_Radio_Peripheral)
> FPGA motherboard with both RX and TX doughterboards is needed, which
> can go up to 1k eur (too expensive for a hobbist).

Depends how motivated the hobbyist is ... I know _plenty_ of people
that pay _way_ more for their hobby.

HAM radio amateurs have a lot of pricy gear for instance. And it's not just EE.
I know guys that like riding motorcycle, how much do you think that
cost ? Or recreational shooting ... guns cost a lot and each clip
fired is literally 5$ up in smoke.

People keep saying the USRP is very expensive ... well, not so much really.

> Speaking of this, what would be the price of the cheapest existing
> packet generator that can transmit them via Um (i.e. what is the price
> of the cheapest BTS)?

The USRP is the cheapest widely available option.

Two notes:
 - You can sometime find BTS on ebay (ip.access nanoBTS, google for
it), but those have been very rare lately AFAICT. (by rare, I mean
none at all that I could see)
 - Several other options are actively being developped, but none will
be available in the short term AFAIK.

> Is there some open source FPGA that can be used for this purpose?

The USRP and board schematics can be found ... and the sw is all opensource.
You're free to build one yourself. Of course it's gonna cost you way
more than buying one.

There is no cheaper, currently available, SDR platform that can run



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