Re: [Discuss-gnuradio] Software mobile phone

[John Gilmore]

> Dear All,
> 
> Do we think it is possible to create a software mobile phone using the  
> USRP, with the OpenBTS code or something else?
> 
> I mean everything would be in software, plus the USRP....?

It is absolutely possible.  So far I don't know anyone who has
tried to do it.  The OpenBTS code would give you a big head start.

I also think it would be interesting to port the resulting code into a
mobile phone.  Generally the GSM protocols in a phone are run in a
"baseband processor" separate from the user interface processor.
Every phone I know of uses secret, proprietary code running in the
baseband processor, even when the user interface is largely free
software.  Once you had working code running in GNU Radio on a Linux
machine, the challenge would be finding a well-documented baseband
chip (in which the manufacturer tells you where to find the radio I/O
gear on the chip, and how it works, etc).  Porting clean GSM code to
run in that chip in realtime would require some adaptation to exploit
unusual on-chip DSP hardware, mastering an embedded debugging
environment, and perhaps shrinking the memory consumption of the GNU
Radio-based code.

I think it's not only doable, but well worth doing.  It should be
worth a couple of PhDs at least.  You would certainly know the GSM
protocols inside and out by the time you were done!

        John