No, OpeBTS does the GSM related DSP. You get a stream of I/Q samples from the USRP, which is more or less just the digitalization of the baseband. OpenBTS carves the time slots and "frames" out of this, does the GMSK de-modulation and similar stuff.
Note that the lower layers of GSM is very different from e.g. ethernet. Once you get past all the very gory stuff up to layer 2, the concepts are pretty much the same though.
Note that the lower layers of GSM is very different from e.g. ethernet. Once you get past all the very gory stuff up to layer 2, the concepts are pretty much the same though.