SIA Asks FCC to Reject MBOA Alliance Request for Waiver
The Satellite Industry Assn. weighed in strongly Wed. against a waiver request filed in Aug. by the Multiband OFDM Alliance (MBOA), one of the 2 main ultra-wideband (UWB) groups. With other comments still coming in, the SIA filing is considered critical since satellite operators are the incumbents that will be most affected by any UWB interference.
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MBOA is led by industry heavyweights Texas Instruments and Intel. Last month, the coalition asked the FCC to waive some of its measurement procedures for frequency-hopping OFDM (orthogonal frequency domain modulation) UWB devices, setting off the latest fight.
The SIA filing will be given considerable weight at the FCC, one regulatory attorney monitoring the UWB wars said. “It’s their spectrum,” he said. “Satellite spectrum starts in the L-band and goes up to the lower Ku- band and that’s where UWB operates.”
“It will be of relevance in that the FCC says it wants to take a cautious approach overall in the UWB context -- if the FCC intends to actually ensure meaning to that statement, it will not grant the waiver,” said a satellite industry source. “If it does proceed, we will be left guessing as to what ‘cautious’ means.”
But Roberto Aiello, CEO of Staccato Communications, an MBOA member, cautioned against giving the SIA filing undue weight. “What I see is negative comments toward UWB in general and not to the waiver and no new technical information offered in regard to the waiver,” Aiello told us: “We have shown through analogies, simulations and field tests that MBOA systems don’t interfere more than other UWB systems currently allowed by the rules.”
A satellite engineer explained the potential interference as “slopes of the ultrawideband spectrum [that overlap] the satellite frequencies and at a higher levels” than it should. While the slopes of the spectrum in a normal transmission can be brought in so they don’t overlap, sending the signals in small pulses doesn’t allow the slopes of the spectrum to “drop off fast enough,” he said. The impact of the interference also depends where the receiver is, he said: “To be fair, it depends on how many of these units there are and how close they are. Obviously, if you listen to the hype, they talk about millions of these units everywhere.”
However, restricting the band would be less helpful than adopting a more-stringent spectrum skirt, the engineer said, whether or not the operator uses frequency hopping: “Then the [operator] would have the option of either controlling the skirts or not using the full band.”
“Even if UWB devices do not, by themselves, cause harmful interference, they nevertheless eat into the margin that satellite operators have set aside,” SIA said in its filing. UWB operations have the “potential to degrade service below what satellite operators have committed to in their agreement with their customers or to disrupt service entirely” because of its uncoordinated nature, the group said. With that in mind, SIA said MBOA shouldn’t receive a waiver of certain measurement procedures simply because the frequency-hopping OFDM (orthogonal frequency domain modulation) methods it plans to use weren’t considered when the measurement procedures were designed. Instead, appropriate techniques need to be developed, and waiving procedures won’t accomplish that, SIA said.
SIA also opposed MBOA’s request to turn gating off when measuring the signals. The current measurement method tests the length of the “gated” quiet period to the periods between repeated pulses. In its filing, MBOA argues its method never uses gating, and using the method that would include a quiet period wouldn’t be applicable to the operation of its devices. But SIA said without the gating function, an average of the pulse levels is taken and “interference effects cannot be assessed by averaging interference power over time.” However, SIA said results of tests indicate the OFMD “systems have the potential for causing more interference than pulsed UWB systems that have been tested including blanking intervals between successive pulses in the train.”
One source who supports controls on UWB said MBOA’s arguments may get a skeptical reception at the FCC. “The MBOA is generating its own test data and saying trust us,” he said: “What they need to do is turn that data over to a reputable 3rd party such as a government agency and let them work through the information.” NASA and the Dept. of Transportation in particular have already done years of testing, the source observed.