Today's wireless industry is rapidly expanding with multiple standards and devices. New wireless technologies are being introduced at a progressively increasing pace. Software defined radio (SDR) provides a framework to support multiband-multimode radios, global roaming, runtime reconfigurability, and over-the-air-programming, thus potentially alleviating issues arising with the deployment of the new communications standards. SDR has additional benefits such as improving spectrum utilization, which further increases the value of the technology. With all these features, SDR provides the enabling technology for exciting, promising, new communication systems such as those envisioned by the U.S. Department of Defense's Joint Tactical Radio System (JTRS), Defense Advanced Research Projects Agency's (DARPA) neXt Generation (XG) Communications program, and the Federal Communications Commission's (FCC) Cognitive Radio Technology Proceedings.
A SDR is a communications device whose operation from the physical layer through higher-level protocol layers is principally defined in software. SDR provides the flexibility of changing a radio's operational ability simply by changing the software code in the device's processing hardware. The architecture of such a device is built around advanced signal processing subsystems which control analog-to-digital converters (ADC) and digital-to-analog converters (DAC). The ADCs and DACs interface the digital processing hardware and software to the physical layer basedband electronics of the device. The ADCs and DACs also interface to the RF front end of the device.