Where’s public-safety’s interest in SDR
Recently I spoke with Fred Frantz and Allan Margulies from the Software Defined Radio Forum, who brought me up to date on the results from a request for information that the Forum’s Public-Safety Special Interest Group issued in November.
The PSSIG was seeking specific ideas regarding how SDR technology can meet public-safety interoperability requirements. Among the things the Forum hoped to learn is how to leverage the investment the military has made in its Joint Tactical Radio Systems (JTRS) program, which was created to help the armed forces migrate from their current radio systems to SDR. While many of the military’s requirements are shared by public safety, many others aren’t needed and would result in form factors and price points that could keep SDR beyond public safety’s reach.
According to Frantz and Margulies, analysis of the responses resulted in the identification of issues that need to be resolved, as well as areas of consensus. One point of agreement concerns the need to better understand the economics of deploying SDR technologies in the public-safety environment. “What it comes down to is, can something be implemented at a price point that can be afforded by public safety?” Frantz said.
A key issue concerns the role of standards in SDR development. According to Frantz, there are two schools of thought. The JTRS program developed the Software Communications Architecture to ensure that SDRs manufactured by different companies could communicate with each other. “The SCA essentially gives you an inter-device interface standard,” Frantz said. “That’s a different way of approaching standards than what you typically find in public safety.”
An example of that model is the Association of Public-Safety Communications Officials’ Project 25, which focuses on standardizing the interface between subscriber equipment and the underlying infrastructure, or between infrastructures, Frantz said. “But it doesn’t get down inside the radio to create an interface between the waveform and the operating platform of the radio,” he said. “The case for the JTRS model is that it reduces the cost of porting the waveform from one operating platform to another.”
Another advantage is that the SCA would let vendors specialize in hardware or software platforms. But Frantz predicted that public-safety wouldn’t adopt the JTRS model in its entirety. “Public-safety vendors always have been fully responsible for the integration of equipment and ensuring reliability,” Frantz said. “That goes away when you allow the loading of different waveforms on a single device. Who’s at fault if something goes wrong?”
After listening to Frantz a while more, I asked a standard question: how many responses did the PSSIG receive? The answer startled me — eight, and none were from a public-safety entity. The organization that came closest was the Texas Department of Transportation.
When I asked how the PSSIG could draw any meaningful conclusions from such a small number of responses, Margulies said, “this is not a market survey or focus group where you need [hundreds of] responses” to achieve statistical verity. He said the RFI is just part of a larger effort that has gathered input from about 20 additional agencies, including radio vendors, public-safety agencies, regulatory agencies and software vendors. In addition, the PSSIG itself is heavily involved in the standards effort, Frantz said. “In this group are the people who have the best understanding of technology and the public-safety environment.”
It’s difficult to argue with Frantz on that point. Nevertheless, it seems odd that the RFI didn’t produce even one response from a public-safety entity, especially considering that the PSSIG extended the deadline for submissions at least once. It makes one wonder just how interested public safety really is these days in SDR technology.
It also makes me think of the following adage: if you’re not part of the solution, then you’re part of the problem. Unless public safety does a better job of weighing in on SDR, it will have a difficult time justifying criticism of any SDR standard developed.
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