Software Radio

NSF funded research at Vanu, Inc., has produced a Linux-based PC software system which works as a cell phone base station. When Vanu founder Vanu Bose was at MIT’s Lab for Computer Science (now part of the new MIT Computer Science and Artificial Intelligence Laboratory) he slightly modified a regular Linux kernel, attached a little piece of analog circuitry that pulled out a 10Mhz chunk of the radio spectrum and fed it through an analog to digital converter into the PC’s memory. Then he used software to do everything else that a radio receiver would normally do in analog–even a 1998 PC was fast enough. It was just a few hundred lines of C code to build an FM radio receiver, less than a thousand lines for a TV receiver, and I recall that even then he had a cell phone receiver written.

The implications? Ultimately we won’t need to buy new cell phones to use different protocols, even ones developed after our phone was built; the Japanese PHS system should run on our GSM phone just fine–all it will take is a new software download. And our phone should be able to run 802.11b, or 802.11g, or 802.11w, or whatever is developed, since it will just grab an enormous chunk of spectrum and do everything else in software. The universal radio device of the future will be all software.