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Carriers lock on to soft radio

Posted: 01 Feb 2006 ?? ?Print Version ?Bookmark and Share

Keywords:patrick mannion? ee times? sdr? sdr technology? sdr tool?

Software radio is here. Long sought after for its economics, the technology has been stymied by engineers' inability to make it consistent, reliable and cost-effective. Now, with deployments afoot among carriers worldwide, the technology is winding its way from the lab to the street, even though a number of knotty technical issues remain unsolved. From the antenna and the baseband processing required for each waveform to the development environment needed for rapid deployment, complexities continue to fuel intense innovation.

"SDR is no longer a concept!it's real-world," Toney Prather, a partner in MidTex Cellular, said at the SDR conference in Anaheim, California. 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 SDR.

Cheap upgrades
The cost argument is hard to refute. Instead of large base stations 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.

Programmable angle
Meanwhile, the traditional FPGA/DSP/ASIC paradigm continues to evolve. In a keynote speech at the SDR conference, Misha Burich, senior VP 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.

"Programmable means we can invest once in a technology that can be applied to many industries," he said. However, designing with combinations of FPGAs, GPPs and structured ASICs remains problematic.

"We need to use higher levels of abstraction," Burich said, pointing to C and C++. Although he questioned the suitability of such languages for the "rich, distributed-computing paradigm," Burich found hope in what he termed "C-to-gates" companies and their tools, such as Celoxica and its SystemC, and Mentor Graphics with its own variation, Catapult C.

While baseband processing continues to develop rapidly, the RF front-end chain needed to make agile jumps among the various bands lags behind. So important is this technology that almost to a man, a panel of venture capitalists at the conference cited an appropriate RF technology as a major must-have for successful SDR rollouts.

"Frequency agility is very important for the front-end," said Jim Smith of InQTel, a company backed by the intelligence community, including the CIA and FBI. For Smith, "800MHz to 2.45GHz covers most bands of interest."

Aside from innovative baseband architectures, the panelists pointed to a number of other key technologies that will be needed to make SDR mainstream. They include displays, batteries, smart antennas, UWB and the concept of spectrum sharing through cognitive radio.

But for startups intent on getting funding for development in these areas, Quinn Li of Qualcomm Inc. laid out the ground rules. "It's the three M's!market, management team and money," he said. "We need to see a return on investment."

"We look for a return and a company that fits with our strategy," said Dan Docter, senior manager of strategic investments for Intel Capital. "We also look for passion and a belief in what they're doing."

Startup BitWave Semiconductor Inc. is among those attacking the RF front-end problem. Focused on the development of an agile RF front-end that can run the gamut from Wi-Fi to high-speed downlink packet access, the company announced that it developed a digitally-tunable architecture that accommodates all those standards without sacrificing power, cost or space.

Where are the tools?
While the hardware is developing rapidly, the tools required to enable the true portability of waveforms from platform to platform lag. Many pin their hopes on the software communications architecture, or SCA, which is currently at the ver 2.2 stage. Developed under the auspices of the Defense Advanced Research Projects Agency's Joint Tactical Radio System (JTRS, or "jitters") program and pushed as the platform of choice for future radios, SCA has fallen into limbo. "Version 3.0 is on strategic pause," Mark Turner, director of Harris Corp.'s RF communications software and security products engineering organization, said. According to those close to the technology, the pause is mainly due to a reorganization of JTRS.

The result is that vers 2.2 lacks the APIs needed to allow rapid development across multiple platforms and systems. "We need a unified path to the adoption of APIs," said Turner. In addition, he said, standardized hooks to enable development of SDR waveforms on conventional DSP or FPGA architectures are missing.

To accelerate SCA's pace, Steve Bernier, project leader for SDR at Canada's Communications Research Centre (CRC), said that the SDR Forum will propose to the JTRS that it take over SCA's development.

While SCA is being pushed as the end game for SDR development, it's not perfect. Jeff Reed, a professor of electrical and computer engineering at Virginia Tech, cited SCA's reliance on what he maintains is the processing-intensive Corba core as a weakness. But, according to CRC's Bernier, that supposed flaw is overrated; Corba-based designs can be optimized so as to make the initial connection between SCA components and then get out of the way. "We can switch between components in 10s," he said, vs. the standard 100s.

CRC has partnered with Green Hills Software Inc. and Object Interface Systems to provide what Green Hills announced as a complete development environment for SDR. "Designers wanted someone to come up with all the pieces. And we have," said Dan Mender, director of business development for Green Hills.

- Patrick Mannion
EE Times

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