Meanwhile, farther north, the Laboratory for Computer Science at the Massachusetts Institute of Technology (MIT) has developed a powerful, multipurpose, handheld computer that combines the functions of a cellular phone, a wireless connection to the Internet, a pager, an AM/FM radio, and a television set. Probably one of the most innovative applications of SDR, the Handy 21 replaces many current communications gadgets with a single portable device. Selecting each function is similar to selecting applications using a mouse and a computer. The hardware is essentially a PC equipped with an antenna and a wideband ADC. The hardware allows the selection of any 10-MHz region of the spectrum, converts it to I-F, and then relays the signal to the main memory of the handheld personal computer.
MIT is also developing a universal logic chip, called a Raw chip, that will deliver excellent performance and energy efficiency at low cost. The chip may be customized to suit a very wide variety of applications. Intended to replace both general-purpose microprocessors and special-purpose ICs, the Raw chip has more than 1000 I/O pins that can be dedicated to data streams–about 10 times more than in today’s microprocessors. The faster data input will yield much better performance and energy efficiency than is possible today.
To sum up, software-defined radio concepts span all types of wireless computing devices, offering the possibilities of enhanced flexibility, easier upgradability, improved performance, and even customizing radio devices to individual needs. The concept will really have a chance to prove its worth when and if it is accepted as a platform for innovative new services that can be downloaded from the network. It will be interesting to see whether incumbent service providers have the foresight to seize this opportunity or whether it will be a flock of as-yet-unheard-of new entrepreneurs who provide the killer applications and reap the killer rewards.
Michael J. Riezenman, Editor
The lead author is grateful to Zoran Zvonar, who reviewed the original version of this article and provided many useful insights.
About the Authors
BENNY BING (M) and NIKIL JAYANT (F) are faculty members at the Georgia Institute of Technology (Atlanta). Bing is a research professor in the electrical and computer engineering department. His publications include 5 books and over 30 technical papers. Jayant is John Pippin Chair and Professor of Electrical and Computer Engineering. He also serves as executive director of the Georgia Centers for Advanced Telecommunication Technology. Before that, at Bell Laboratories, he was involved with signal processing research, audio technology, and multimedia communications.
To Probe Further
A good source of background information on software-defined radio (SDR) is Software Radio Technologies–Selected Readings (IEEE Press, 2001). It is edited by two acknowledged authorities in the field, Joseph Mitola III and Zoran Zvonar.
For more on the Joint Tactical Radio System (JTRS), a U.S. military system that allows software-based transceivers to simultaneously carry voice, video, and data, see Daniel G. Dupont, “Reengineering the Radio,” Scientific American, July 2000.
The Massachusetts Institute of Technology’s Handy 21 device is described by John Guttag in “Communications Chameleons,” Scientific American, August 1999.
The Web site of the SDR Forum is at http://www.sdrforum.org.