> With SDR (software defined radio) would it not be possible to design / > develop a cheap GSM basestation?
See OpenBTS. It uses the USRP wich brings down to ~1000 eur. Several company are working on custom hardware for OpenBTS, but for a really low price, you need large quantity ... > I am a total noob on hardware development but I suppose there is a large > market for this. You need a license ... so I'd assume the bulk of the market is operators. And for them 2-5k EUR is already dead cheap for a BTS. > Or maybe somebody already working on reverse engineering other base stations > like the nanobts? There are not that many IP based BTS on GSM (not talking 3g here). > Or might something simpler be possible with modifying a router and with a > different antenna on 1800mhz? Not a chance, you need either: - custom hw dedicated to GSM: Doesn't exist cheap yet because of qty. (might happen since some company are working on it using openbts, but no price/data yet). - or something flexible enough like the USRP (but then, it's not a 'consumer' product and so not _that_ cheap).