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Lawmakers Look Into Receiver Standards
11/29/2012

WASHINGTON – There are viable alternatives to federal receiver performance standards, witnesses told lawmakers at a hearing today.

Pierre de Vries, senior adjunct fellow at University of Colorado, Boulder’s Silicon Flatirons Center (pictured), said mandating standards should be a “last resort.” He suggested instead that the Federal Communications Commission set “harm-claim thresholds” that define “the interfering signal levels that must be exceeded before a service can bring a harmful interference claim.”

“If the interference is below this number, you cannot claim harm,” he said. “If it is above this number, you can.”

The House Subcommittee on Communications and Technology held the hearing to explore how increased receiver efficacy could mitigate demand for more wireless spectrum. In many cases, receivers are now protected from co-adjacent interference by guard bands, or null spectrum that otherwise could be deployed for services.

The hearing was also an elemental post mortem of the erstwhile LightSquared LTE network. GPS receivers were not robust enough to reject LightSquared’s proposed terrestrial transmissions in the adjacent band, so its plan was halted. The company, in which investors placed nearly $4 billion, went bankrupt.

“What happened to LightSquared is unfortunate, but it’s not the first time an incumbent has raised the issue of receiver overload,” said Ranking Member Anna Eshoo (D-Calif.) At the same time, she said, people want their tablets and their smartphones, but they don’t want to pay more for them—a possible result of receiver standards.

With regard to guard bands, Eshoo and Subcommittee Chairman Greg Walden, (R-Ore.) asked how much spectrum could be salvaged from them. de Vries said it was a function of where interference rejection levels are set.

“If I have a receiver in this band, if I set the rejection level very low, that’s essentially a guard band. If I set it very high, it’s not,” he said. “Where that number is set influences how much we can squeeze in.”

Eshoo asked Ron Repasi, deputy chief of the FCC Office of Engineering and Technology, if filtering technology could be improved such that it might eliminate the need for guard bands.

“No, not in all cases where you have two adjacent services,” he said. “With current technology, even in the PCS world, you have downlinks in one band, and uplinks in another. One could interfere with the other if you don’t have a sufficient guard band between them.”

Filters are improving, he said, but not in “leaps,” as Eshoo inquired.

Neither members of the subcommittee nor the witnesses seemed eager to direct the FCC to establish receiver standards. There was even general uncertainty about the FCC’s authority to do so.

Rep. Cliff Stearns (R-Fla.) said lawmakers should be wary of government regulations dictating receiver design. Rep. Lee Terry (R-Neb.) said he understood that the FCC favored that approach.

Repasi said the commission has generally focused on transmitters as opposed to receivers. Receiver performance has been left up to the marketplace. He said the commission initiated an inquiry into receiver performance in 2003, but it was terminated in 2007. More recently, FCC Chairman Julius Genachowski has directed the commission’s Technical Advisory Committee to look into receiver standards.

“We’re in a little bit of a wait mode,” he said. “We want to be sure that we don’t curb innovation. We had that in the 2003 NOI that we released…. There was concern in the records that standards could curb innovation.”

The third of the three witnesses was Brian Markwalter, senior vice president of Research and Standards at the Consumer Electronics Association. He argued for industry coordination versus performance mandates.

“Manufacturers have a strong self-interest in developing and deploying devices that are resistant to forms of interference, and devices that create as little interference as possible,” he said.

He held up digital TV receivers as an example of “effective response by industry stakeholders to document the RF environment and the associated tradeoffs made by receivers to operate in the wide range of expected signal levels.”

Walden asks if unlicensed devices should be treated differently from licensed devices.

de Vries said depending on the level of risk accepted. Congress could, for example, require manufacturers to certify that their receivers will work.

Eshoo asked how government users might benefit from establishing harmful interference criteria. Federal users, particularly those in Defense, played a pivotal role in LightSquared’s jeopardy because so many military systems rely on global positioning systems.

de Vries said it would allow them to develop systems that would be more interference tolerant, more jamming tolerant. Doing so, he said, merely involves setting a number. The rest is left up to the industry. He said he could not speak to the defense community’s openness, but that “they may find more clearly defined boundaries more attractive.”

Terry asked Repasi how long it would take for the FCC to establish a harm-claim threshold. Repasi said the Technical Advisor Committee is discussing the option, as is the Government Accountability Office. Both are expected to deliver reports on receiver performance early next year.

If a harm-claim threshold is recommended, Repasi said the FCC would still have to consider it on a case-specific, band-specific basis. A threshold for a receiver looking into space might be much lower than one communicating with a wireless broadband system, he said.

Terry asked what would be necessary to apply a new threshold to incumbent receivers. Markwalter said that right now, it’s a hardware issue.

Markwalter said one thing manufacturers are currently focused on the complexity of band plans, especially as related to cellphones.—things that inhibit phones from being used for different carriers in different bands.

“We conjecture where there’s a time in the future where receivers can be more agile. We’re clearly not there yet,” he said. “What you’d like to do is have receivers that are cost-effective and can be agile in the future.”

Walden asked de Vries what role policymakers should play.

He replied that receiver performance is “a long-term problem. Everybody’s tendency is to punt.” He said lawmakers should “focus on encouraging the FCC to set these clear boundaries., and remove any uncertainty that the FCC has the ability to do that.”

~ Deborah D. McAdams

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