Software mobile phone

GNU Radio
1

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…?

Abdalaleem

2

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

3

And leveraging the work from the osmocombb project
(http://bb.osmocom.org/trac/) will get you a far ways towards the goal.

Quoting John G. ([email protected]):

4

Fantastic stuff!

5

Hi,

The OpenBTS code would give you a big head start.

The tranceiver part sure. But you’d still need pretty big modification
to have it act as a TDMA clock slave and not TDMA clock master (that’s
quite different).

Once you have done the L1 inside the USRP somehow, you can re-use the
osmocom-bb code (which is an opensource baseband implementation project)
for the upper layers.

Sylvain M.