Software-defined radio (SDR), software radio (SWR), and cognitive radio (CR) are futuristic concepts that promise to significantly impact wireless communications technologies. Today, however, technology ironically is one of the limiting factors in the production of a true software radio that is capable of dynamically reconfiguring itself to meet user requirements or spectral limitations. Specifically, the lack of analog-to-digital converters and digitalto- analog converters fast enough to implement a software or cognitive radio will delay their deployment. Fortunately, fast-developing ultra-wideband (UWB) technologies might provide the solution to this dilemma. © 2012 River Publishers. All rights reserved.