"Software-defined radio [SDR] is no longer a concept — it's real world," Toney Prather, a partner in MidTex Cellular, said at the Software Defined Radio conference here last week. Citing the company's newfound ability to compete against big-name carriers thanks to equipment from Vanu, Hewlett-Packard and ADC, Prather contended that SDR technology made it possible to deploy new services more effectively and at lower cost.

"The biggest savings is in upgrade and maintenance," he said, underlining the long-held argument for software-defined radio. "We have 2,800 customers on it, or 20 percent of our customer base." Combined, those customers account for 30 percent of the carrier's traffic.

Prather made it clear that SDR means little to those users, who may not know or care how their cellular service is delivered. However, for MidTex and the many carriers — small and large alike — embarking on SDR rollouts, the ability to cover any and all local bands with a single, relatively low-cost basestation that lends itself to remote upgrades represents the holy grail the wireless industry has long been chasing.

Cheap upgrades
The cost argument is hard to refute. Instead of large basestations that sell for hundreds of thousands of dollars apiece and need constant upgrading and replacement, Prather described a system from ADC, Vanu and HP priced at a small fraction of that amount, and which can be upgraded two years hence "for a few hundred dollars."

SDR has been long in gestation and fraught with false starts. The technology — which requires high-end processing for baseband signals, agile RF front ends to accommodate each and every potential band, and a development environment upon which academics, researchers and designers can innovate — has long been considered a military-only proposition.

That said, the barriers to SDR are rapidly disintegrating. Moore's Law and innovative software have combined to provide the processing horsepower needed on the basestation side, in order to switch among standards such as GSM, CDMA, Edge, wideband CDMA and its derivatives, such as high-speed downlink (and uplink) packet access. While combinations of FPGAs, ASICs and general-purpose processors continue to form the vanguard, companies such as picoChip (Bath, England) have developed innovative reconfigurable processing architectures — and the development tools to go with them — to accommodate the requisite processing requirements.

Such architectures rely on advanced designs centered on multiple cores or processing elements. However, SDR can be approached more simply: In recognition of its development efforts predicated upon the idea that SDR can be accomplished using conventional, general-purpose processors, Vanu Inc. (Cambridge, Mass.) last week won the SDR Forum's industry achievement award. CTO John Capin accepted the prize for Vanu.

Programmble angle
Meanwhile, the traditional FPGA/DSP/ASIC paradigm continues to evolve. In a keynote speech last week at the SDR conference, Misha Burich, senior vice president for system engineering at Altera Corp., said that with ASIC development costs growing exponentially and the cost and power consumption of programmable devices falling, the industry is knee-deep in programmable technologies.