A software radio is a wireless communications device that performs all of its signal processing in portable, application level software. By simply running a different program, a software radio can become a cell phone, wireless LAN, cordless phones, garage door opener or walkie-talkie. The flexibility enabled by software radio also enables faster technology tracking, since standards upgrade are simply software downloads. Software radio is a multi-disciplinary systems effort, bringing together research in digital signal processing, communications, operating systems, software engineering and algorithms. This talk highlights the research challenges in each of these areas and then describes some features that would be useful in a software radio domain specific processor. From the Series:CSE Colloquia - 2001