LightSquared’s plan for a nationwide wholesale high-speed mobile broadband network that leverages Long-Term Evolution technology increasingly has come under fire because of the network’s potential to interfere with GPS signals across the United States. It’s a situation that may very well turn into a bitter fight in Washington as the Federal Communications Commission looks to fulfill some major policy goals that center on broadband availability.

In January, LightSquared received conditional approval from the FCC to launch services using L-band satellite spectrum, which sits next to GPS spectrum. However, LightSquared must adhere to certain restrictions, which include keeping signals within their assigned frequencies in the L-band. The company also must work with the GPS sector to test existing GPS-enabled devices to determine what type of interference its transmissions might cause. (The company is owned by private-equity firm Harbinger Capital Partners, which purchased SkyTerra — the former Mobile Satellite Ventures — about a year ago and then folded it into LightSquared.)

The FCC also mandated that LightSquared and the U.S. Global Positioning System Industry Council (USGIC) establish a technical working group (TWG) to investigate the issues. A final report is due on June 15 of this year.

While LightSquared reports that this effort is moving along amicably, outrage from GPS vendors is growing. In addition, big industries — such as aviation, trucking and agriculture — and federal agencies — including the National Telecommunications and Information Administration (NTIA), the Department of Defense (DOD) and the Department of Transportation (DOT) — are worried. They are concerned that the FCC moved too fast in granting a waiver to LightSquared, especially because the commission has decided to let resellers of LightSquared’s services offer terrestrial-only devices. Past FCC rules have required satellite operators to offer combination satellite/terrestrial phones, but they continue to have a difficult time finding a business case for the more expensive dual-mode devices.

“We’ve always been playing by the rules, but LightSquared has come in and changed the rules,” said Ted Gartner, a spokesman with Garmin, which has set up a group called, which represents numerous industries that rely on GPS for operations. “All we are trying to do is slow down the process so we can do adequate testing. … We feel this is a real issue for public safety.”

Policy implications

In response, the FCC and LightSquared both point out that ground-based services in the L band have been allowed since 2003 and argue that the GPS sector did not prepare itself adequately for this development. Indeed, the sector didn’t sound the alarm over the potential interference issue until September 2010, even though a public notice made the rounds in 2009 regarding SkyTerra’s request to increase power levels from 1.6 kW to 15 kW, said Jeff Carlisle, LightSquared’s executive vice president for regulatory affairs and public policy. Garmin’s Gartner countered by saying that it is unreasonable to ask the GPS sector to “plan for the unknown.”

Bickering aside, it should be noted that the FCC has made it clear that it won’t allow LightSquared — which already has announced publicly wholesale deals with Leap Wireless, Best Buy and Open Range Communications — to operate without proof its operations don’t interfere with GPS. However, it’s also clear that the commission wants the testing process to move along rather quickly, given that the GPS task force must issue a final report next month.

Should LightSquared’s operations pass muster, it would move the FCC toward fulfilling some large policy goals, such as covering rural areas with broadband services and bringing more spectrum to market. LightSquared has promised to cover 92% of the U.S. population with its satellite/terrestrial combo. A section of the FCC’s LightSquared waiver details how the operator’s service would make terrestrial mobile wireless broadband available to a wider variety of users and that public-safety and homeland-security agencies would benefit from having broadband services when they are operating in — or transitioning between — urban, suburban or rural areas.

Assuming it receives FCC’s approval, LightSquared has an aggressive rollout plan. First, it would launch initial trials in Baltimore, Denver, Las Vegas and Phoenix before the third quarter 2011. Then LightSquared plans to cover 100 million people by the end of 2012; 145 million people by the end of 2013; and at least 260 million people by the end of 2015.

“Everyone knows the way the FCC is leaning. The question is whether other political forces will put a stop to it,” said Tim Farrar, principal analyst with TMF Associates, who has been watching the satellite sector for a long time. “It is a becoming a big political fight, and the president has gone on record talking about how critical it is to free up spectrum for more broadband. But then there are two policies in conflict if the DOD and the [Federal Aviation Administration] persuade the president to overrule the FCC. … LightSquared may very well get caught in the crossfire.”

Jeffrey Silva, senior policy director for telecommunications, media and technology with Medley Global Advisors in Washington, D.C., agreed. “In this post-9/11 world, whenever the DoD gets involved, along with the Department of Transportation, that carries a heck of a lot of weight in the political arena. It’s going to be a challenge for LightSquared to get into operational mode.”

Recently, the two agencies sent a letter to the FCC urging the commission to force a more comprehensive study of the potential interference problems with GPS.

“First, DoD and DOT were not sufficiently included in the development of the LightSquared initial work plan and its key milestones,” stated John Porcari, DOT deputy secretary and William Lynn, DOD deputy secretary, in the letter.”We are concerned with this lack of inclusiveness regarding input from federal stakeholders. In particular, active engagement with DOD and DOT, the national stewards and global providers of [GPS], is essential to protect this ubiquitous defense, transportation and economic utility as the [work group] proceeds.”

LightSquared will be using part of the L-band downlink frequencies in the 1525–1559 MHz band, while GPS (and GLONASS) operates within the 1559–1610 MHz band. Carlisle said that the company’s base stations will be fitted with filters that cut off the signal at the top of the L-band to keep its signals from leaking into the GPS band. The issue, however, is that most GPS devices don’t have strict filtering at the bottom of the GPS band and therefore could be overwhelmed by the high-power transmissions coming from LightSquared’s terrestrial transmissions.

“We originally handled interference in 2003 after the FCC issued its [ancillary terrestrial component] rules,” Carlisle said. “We placed a filter on the base stations that allows the elimination of noise going into GPS. We built to the specs 1,000 times stricter than what the FCC’s rules require. That is what the GPS community needed, and we abided by that. We spent $9 million on the base-station filters.”

Now, according to Carlisle, the FCC is requiring LightSquared to look at receivers that are sensitive to the L band. “Even when we are doing everything we were required to do in 2003, we could still potentially overload some subset of GPS receivers,” he said. “If there are receivers in the embedded base that are impacted by interference, then we’ve got to collectively figure out how to solve it if we are going to deploy our service.”

Third-party testers

In addition to working with the GPS task force, LightSquared also is contributing equipment and personnel to help the DOD, NASA and the FAA to conduct their own tests, Carlisle said. For the purpose of developing test plans, the task force has identified seven GPS receiver categories, covering non-military applications: aviation, cellular, general location/navigation, high precision, timing, space-based receivers and networks.

The users of high-precision GPS equipment are the most concerned about LightSquared’s operations.

“We have received some requests for new custom filters to protect GPS,” said one semiconductor representative who asked to speak on background given that the company’s customers are on both sides of the issue. “When we looked at the filtering requirements for a front-end receiver of a GPS [device] we concluded that there really isn’t a filter at the moment that can provide any additional rejection at 1559 MHz.”

However, Carlisle said that LightSquared believes the problem is solvable, and that the company is still on track to begin its field trials in the second quarter to meet its strict rollout requirements.

“There are many things we can do in terms of zoning and getting base stations set up before anything goes live,” Carlisle said."

Another important aspect is that this is going to be a gradual buildout over time and over the spectrum. It will be a gradual rollout so we can figure out any mitigation work that’s needed. … We can co-exist, and it is possible to have standards going forward.”

Practice til perfect

But the GPS sector doesn’t want LightSquared to roll out services at all until results show inconclusively that users of the technology won’t be impacted by interference. Initial tests from Garmin show that the distant, low-powered GPS signals would receive substantial interference from LightSquared’s network of ground stations. The tests were done using standards that LightSquared has provided, Gartner said.

Carlisle countered that Garmin’s studies weren’t based on equipment that LightSquared plans to deploy in the field. “It’s extremely important to have as high as degree of agreement as we can get around a sound testing methodology,” he said.
Spirent Communications is supplying GPS simulators that will be used to test most of the receiver categories. But while the company is a contributor to the task force’s testing methodology, it is not carrying out any of the tests. Nevertheless, the company said in a statement that the signal generators that will be used to simulate LightSquared’s L-Band (Band 24) signal have the capability to output modulated LTE signals that have the precise characteristics — e.g., frequency, bandwidth and power level — of those in LightSquared’s deployment. Consequently, the tests should provide a clear picture of what will happen once the network is fully deployed.

“Since LightSquared has already published the detailed specifications of their signals, it is possible to ensure that simulated signals very accurately model those that will be seen in the live network,” Spirent said.

So the big question then becomes: If the testing indicates that a fix is needed, how long will it take and what will it cost?

“There is no question in my mind that it is going to cost $1 billion a year for all upgrades and testing,” said TMF Associates’ Farrar “The FCC seems perfectly inclined to place that burden on the GPS community.”

Farrar’s number takes into account dramatically increased costs for testing, safety approvals and retrofits of existing equipment, to name a few. Then there are the increased costs associated with the filter components. At least one semiconductor vendor estimates filter costs for vendors could increase from 10 cents a device to anywhere from 30 cents to 60 cents per device. The cost also will depend on which devices need to be retrofitted with a filter. Mobile phones may not require better filters since they don’t rely just on GPS for to identify location.

“Someone is going to have to pay for this, and we don’t believe it is incumbent on us to pay,” Garmin’s Gartner said. “The person who ultimately pays is the consumer.”

Hence the reason for the rather large public outcry.

While LightSquared has access to a total of 59 MHz of spectrum, the 1525–1559 MHz band is what is available now. The company is paying Inmarsat to transition parts of its spectrum so that LightSquared has a contiguous block of spectrum.

Industry analysts believe that LightSquared very well may have to use just the lower portion of its spectrum — up to 1545 MHz — for terrestrial base stations to avoid interference with GPS. It would be a compromise that could have a significant impact how fast the network will transmit data and how much capacity it will have. But it may be a better solution than being grounded should LightSquared’s transmissions in fact overpower GPS signals.

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