Software defined radio

At first glance, the idea of a ‘software radio’ doesn’t seem to make much sense. But a closer look reveals that it might be an idea whose time has come.

A software radio is a wireless communications device that uses software to perform its entire signal processing functions. Hence, a single communications device can be built that communicates with many different wireless systems simply by running different software. For example, a device could be re-programmed to be an analog cellular phone, a digital PCS phone, or a cordless home phone. In addition to incorporating multiple communication devices into one, a software radio could also be upgraded to enable new standards and services.

Such a software radio was recently put on display at the 2002 Software Defined Radio (SDR) Technical Conference and Product Exposition last week in San Diego, CA. There, MA-based Vanu demonstrated an end-to-end wireless infrastructure system based on its own software radio technology.

All signal processing functions in the software radio are implemented in high-level code running on top of a standard POSIX operating system, not in low-level code tied to the processor or board on which it runs. As a result, the waveforms and signal processing infrastructure can be ported almost unchanged across Intel Pentium, Intel StrongARM, SuperH/Hitachi SH-4, Compaq Alpha and Motorola PowerPC processors.

The technology can be applied to any wireless device, providing a solution to the interoperability problems that face both military and public safety agencies. By simply dragging and dropping icons on a software radio communications console, public safety officers can instantly connect and disconnect public safety radios that are presently unable to communicate with each other.

‘In a disaster situation, many different public safety agencies such as police, fire, EMS and other federal agencies are called in for support. These agencies and departments cannot communicate with each other because they use different radio standards on different frequencies,’ said Dr. Vanu Bose, CEO of Vanu.

‘This lack of communications interoperability can hamper rescue efforts. A wireless device using a software radio, however, will be able to communicate with many different devices, translate the signals between wireless networks and create communications links between today’s incompatible radios.’

Development work at Vanu grew out of the research of the SpectrumWare software radio project at the Massachusetts Institute of Technology. In 1998, most of the SpectrumWare team left MIT to start Vanu. Since then, the company has built software radio implementations of a variety of commercial and government waveforms, including the cellular telephone standards IS-91 AMPS, IS-136 TDMA, and GSM.

‘We are currently working with Vanu to explore the range of applications that the Vanu software radio will make possible. Our initial reviews of this technology and actions are extremely encouraging,’ said John Brennan, Vice President of Strategy and Corporate Development at HP.

On the web