SoftMAC - Flexible Wireless Research Platform

Discontent with the traditional network protocol stack ar- chitecture has been steadily increasing as new network tech- nologies and applications demand a greater degree of flexi- bility and "end to end" information than a strictly layered structure permits. Software-defined radio (SDR) systems have prompted some rethinking of the network stack, and schemes have been presented that attempt to take advan- tage of the opportunities afforded by these flexible radio systems. However, evaluation of these schemes has largely taken place only in simulation or on small testbeds. In or- der to seriously evaluate the utility and efficacy of archite c- tures and heuristics that take advantage of SDR systems it is essential to construct and test these systems "in the wild ," i.e. in environments outside of simulators and the labora- tory. Unfortunately the SDR platforms currently available are not generally suitable for such deployments. We argue that network researchers should begin to de- sign for software defined radio systems and move from sim- ulation to prototypes. To this end, we have developed a software system that allows researchers to use inexpensive , commodity wireless networking cards to experiment with new MAC layer protocols. Individual radios still use the common 802.11a/b/g RF modulations, but by judicious con- trol of the interface we are able to completely supplant the standard 802.11 MAC. On top of this radio subsystem, we have created a software architecture that permits research ers to easily construct and deploy experimental dynamic MAC layers on systems running Linux. We argue by example that such simple software defined radios provide robust, capable platforms for research. Using such inexpensive tools will allow wireless network research to address a number of the opportunities of software defined radio.