SDR (systems defined radio): how do we get there from here?

The SDR, which normally means software defined radio, is a major change from earlier radios. Functionality is predominantly realized in software (SW). SDR hardware (HW) is predominantly computers and data buses rather than RF/IF elements. SDRs are complex "do everything" radios. Object oriented analysis/object oriented design (OOA/OOD) has become a mainstream SW methodology over the past decade. These changes make definition of radio requirements, translation of these requirements into radio architecture and design, and description of SDR functionality more difficult. The modern radio is in fact a complex system and needs to be treated as such if these challenges are to be successfully met. An approach to achieving this is presented that marries conventional top-down functional decomposition with OOA/OOD.