Deborah D. McAdams /
11.29.2012 02:53 PM
Lawmakers Look Into Receiver Standards
‘Harm-claim threshold’ suggested as an alternative
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
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
Walden asks if unlicensed devices should be treated differently from licensed
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