Software radio is a new way to build wireless communications devices with the potential to radically reshape the communications industry. A software radio implements all the signal processing functions of a communications device in a user-level process, written in a high- level language and running on a commodity processor and operating system. Nearly all of the custom hardware traditionally associated with communications devices is thereby converted into software which is portable across generations of commodity platforms. The resulting systems improve in performance, price, and other metrics along the Moore's Law curve of the computing industry, while providing significantly more flexibility than current communications devices. In this talk I will introduce the software radio rationale, implementation architecture and markets. The technical focus will be on achieving reliability and scalability through using workstation clusters as the execution platform. Software radio has substantially different characteristics from previous cluster applications, requiring novel systems software solutions.