FCC Open Minded on the Need for Agency-Imposed Receiver Standards

"The sentiment is against do nothing,” said Dale Hatfield, former OET chief, who has long urged the FCC to take on receiver standards. “I think we're finally at a stage that we recognize that we really do need to do something about receivers. Now we can have big battles about exactly what that should be.” One choice policymakers must make is whether to specify the environment within which a receiver must operate, complete with receiver interference limits, or impose actual receiver standards. “The sentiment seems to be in the direction of giving manufacturers, system designers … flexibility in how they deal with the interference environment,” Hatfield said.

Another key choice for policymakers is whether multi-stakeholder groups like 3GPP are best positioned to set the rules of the road or the FCC and NTIA need to play a larger role, Hatfield said. “It seems the sentiment is toward the multi-stakeholder solution.” But industry-led efforts might not work when conflicts arise between military radar and commercial operations. “Then you have different cultures,” he said. “It’s hard to know who to negotiate with. … I think we have to be a little bit cautious.” Hatfield cited the “good fences make good neighbors” analogy from Monday’s discussions (CD March 13 p1). “It’s one thing if you have two farmers on each side. … They're sort of in the same business, they sort of understand each other,” he said. “What happens if there’s a farmer on one side and there’s a gravel pit operator on the other? Then it gets a little harder.”

"The time to act is now on receivers,” said Dennis Roberson, vice provost at the Illinois Institute of Technology, who built a case for regulation. “We have moved as we invented new wireless technologies to a position of an ever more complex set of standards-based sharing,” he said. “Transmitters don’t interfere with one another. … The only place that there’s any interference is at the receiver. We need to recognize that and, therefore, put the focus on the receivers.” Any system that’s based only on putting filters on transmitters “can’t work,” Roberson said. Cellular and other systems already have receiver standards in place, but they remain largely invisible, he said. “We need to make those standards fully visible and even require adherence to those standards through regulation.”

During a second presentation Tuesday, Evan Kwerel, an FCC senior economist, suggested one alternative would be to protect licensees based on the highest use of the spectrum, rather than the current “first in time, first in rights” approach, which safeguards incumbents from newcomers as its bedrock principle. “What’s wrong with this system? Well, yesterday was a full day of saying what’s wrong with this system,” Kwerel said. “The bottom line is it wastes a large amount of spectrum. … The existing uses aren’t necessarily the highest value uses.”

Under the proposal, legacy systems would be protected for a limited amount of time, when spectrum in an adjacent band was reallocated for a higher use, such as broadband, Kwerel said. “This would be sort of like GPS and LightSquared,” he said. “GPS was the legacy system. We're not going to flashcut. … We would give the legacy system a certain amount of time based on the replacement cycle of their receivers.” The plan would regulate power levels, a key question, at the transmitter level, Kwerel said. “It makes life for the people operating transmitters simple,” he said. “They know what they've got to do. … It deals with the most difficult cases of interference, like mobile to mobile."

With an increasingly diverse group of players offering wireless products and services the number of fights over spectrum will only grow, said Pierre de Vries, a fellow at the Silicon Flatiron Center at the University of Colorado. “It’s clear that the FCC is already struggling to resolve disputes,” he said. “It takes a long time even with the situation we have now. So that’s not tenable going forward.” Another issue that must be worked through is the lack of clarity on definitions, de Vries said. “There’s a lack of a definition of what harmful interference means and there’s a lack of a definition of what the signaling environment is.”

The FCC also needs to address the “asymmetry” in how transmitters and receivers are treated under current regulation, de Vries said. “It takes two to tango.” The answer might prove to be clearer operating rights, including receiver interference limits, he said. “It delegates more of these optimizations … to the players,” he said. “It’s not always going to work. There are always going to be hard cases that the FCC will have to deal with, but try to offload as many as possible of the more mundane ones, the way that the cellular players already solve almost all their problems amongst themselves.” When looking at power limits, the FCC must consider both transmitters and receivers, de Vries said. Looking at power limits at transmitters is like looking for lost keys under a lamppost, he said. “The light is very bright there, but that’s not where your problem is. The problem is, we all know, that interference is out there in the world. It’s not at the antenna.”

The time is “ripe” for the FCC to take on receiver issues, agreed Steve Sharkey, chief of engineering and technology policy at T-Mobile. “In fact, I think it’s overripe for action,” he said. “This has been heating up as we've seen issue after issue where there’s been interference and some of the cause of that has been receiver interference.” Defining the interference environment, as the commission did when it addressed 800 MHz interference issues, is critical, Sharkey said. The agency’s message as it addressed 800 MHz problems was “'Public safety, you've got to design your system to live with a certain power-flux density [PFD],'” he said. “If you receive interference at a lower PFD than that, then it’s your problem. You've got to resolve that.'"

"I think it is time to move forward,” said Sprint Nextel Vice President Larry Krevor. “A carrier at the end of the day is looking to set up its system to provide the best possible experience for the customer. … That means using the spectrum more and more intensively. I think there’s no question that going down this path and dealing with receiver standards and not just transmitter performance is certainly what needs to happen going forward.”