Could Satellite Messaging Startup Higher Ground Bring Down the 911 System?

A smart phone with Higher Ground's satellite attachment Satpaq on the back.
Illustration: IEEE Spectrum, Photo: Higher Ground

Higher Ground might be the only Silicon Valley startup promising not to disrupt its entire industry. This small satellite messaging business is battling claims by telecoms companies that its SatPaq device could interfere with their services, interrupt life-saving emergency calls and even cause major outages across the United States.

IEEE Spectrum can reveal that for the past several years, Higher Ground has been quietly developing SatPaq, a smartphone case with a flip-up antenna that communicates with geostationary satellites. Connecting to a smartphone messaging app via Bluetooth, SatPaq can send and receive text messages and email almost anywhere in the United States, including the wilds of Alaska.

The problem is that SatPaq works in the same C-band microwave frequencies used by CenturyLink and other companies for voice and data communications in rural areas and as part of their national networks. They fear that the widespread use of SatPaqs could result in catastrophic interference.

“[This] is not just potential interference to one or two specific links in a particular location but… potential interference to each and every such link of the network throughout the country,” wrote CenturyLink in a submission to the Federal Communications Commission (FCC). “This seems to be a recipe for disaster.”

Higher Ground, which appears to be operating from a private home and co-working office space in Palo Alto, Calif., denies that SatPaqs pose any threat to existing microwave stations. The devices have a self-contained interference protection system that the company says will mean zero possibility of interference.

Even though Higher Ground is currently in stealth mode, Rob Reis, the company’s CEO, agreed to an off-the-record interview with IEEE Spectrum to discuss its dynamic frequency sharing system. Spectrum pieced together further information about SatPaq’s capabilities from documents filed with the FCC.

Higher Ground first received permission from the FCC to test the SatPaq in June 2014. Unlike today’s satellite messaging devices, which connect to the Iridium constellation orbiting at an altitude of 780 kilometers, Satpaq uses Intelsat’s geostationary Galaxy satellites—another 35,000 km out.

That distance means the SatPaq needs to pack quite a punch. Its microwave signal is (just) below the legal maximum power density for consumer mobile devices at a distance of 20 centimeters from the quad patch antenna. If anything gets closer, an infrared sensor turns off the transmit beam immediately.

Also, Satpaq has to be oriented fairly precisely. Higher Ground’s app uses the smartphone’s GPS and compass to activate the SatPaq’s antenna only when it is pointing in the right direction, deactivating it in a tenth of a second if the phone swings more than 15 degrees off-target.

“This process is fast enough to permit mobile operation of the SatPaq for many recreation activities, such as hiking, boating, and horse-back riding,” wrote Higher Ground to the FCC. The company did not specify data rates in its communications with the FCC but admitted that the service is only suited to “light” email.

Despite its limitations, Higher Ground told the FCC: “Outside of cellular network coverage areas, SatPaqs will be the only truly ubiquitous, affordable, consumer-priced two-way communications option available.” It called existing mobile satellite services “bulky, distinct devices that are too costly to serve the consumer market” and promised that “SatPaqs [will be] less costly to produce and operate, and offer greater convenience.” Reis would not reveal a launch date or pricing for the device. However, a half-finished website accessible on some mobile devices suggests that SatPaq devices will sell for $139, with texts and emails priced pay-as-you-go, no subscription required. The device should also be able to recharge the smartphone with its built-in battery.

Higher Ground also envisages SatPaqs being used for internet of things (IoT) applications, such as  communicating soil conditions, detecting agricultural pests, and monitoring livestock far from cellular networks. “Someday we hope to have one million SatPaqs in use,” says a document filed with the FCC.

Initial trials of the SatPaq took place in Redwood City, Calif. They presumably went well because last June Higher Ground asked the FCC for permission to expand testing to Anchorage, Alaska; Las Vegas; and Washington D.C. Looking forward to a commercial launch, the company also applied for a blanket license from the FCC to operate up to 50,000 SatPaq devices nationwide.

But for all its proximity to Silicon Valley’s tech giants, as a test site Redwood City is lacking. It’s more than 200 kilometers from the nearest thing SatPaq could potentially interfered with:“point to point” microwave stations for beaming data or voice calls. Higher Ground was now asking for permission to activate thousands of portable microwave transmitters under the noses of licensed users of the same spectrum. And they weren’t happy about it.

CenturyLink, which has approximately 850 fixed microwave stations using frequencies in SatPaq’s 5925 to 6425 MHz uplink band, was the first to complain. “These facilities support E911 circuits that enable life-saving emergency communications,” the company wrote to the FCC in early September. “They may also provide links that aid the Federal Aviation Administration in airport operations [and] serve as diverse circuits that can be critical … if a primary circuit goes down.”

CenturyLink was concerned that sporadic interference from passing SatPaqs would be difficult to identify and troubleshoot: “This could include interference that is so disruptive that it terminates communications through that facility and thus bring down communications on the network, possibly even causing a major outage.”

Two industry bodies, the National Spectrum Management Association (NMSA) and the Fixed Wireless Communications Coalition (FWCC), representing licensees, regulators, providers, users, and manufacturers of microwave communications equipment, also urged the FCC to deny Higher Ground’s application. “It is extremely dubious that the public interest would call for potentially jeopardizing tens of thousands of established microwave facilities in favor of providing messaging… for tourists and recreationalists. Simply put, this is a bad trade,” wrote the FWCC.

Interference is always a worry for services operating in the same frequency bands, and the FCC has a well-established procedure for coordinating users so that the risk of interference is minimized. Anyone planning a new satellite earth station usually has to give the FCC highly detailed maps, interference analyses and technical plans, and submit to a 30-day notice period for nearby licensees to respond.

This would obviously be impossible for SatPaq owners wanting to just flip up their antennas and send a text. Higher Ground’s solution is for each SatPaq-equipped smartphone to check its GPS location against on-board databases of the locations and frequencies of fixed microwave stations, before transmitting anything. In the unlikely event that a non-interfering frequency could not be found, the app would instruct the user to move and try again.

Higher Ground claims that its geo-fences around fixed stations like CenturyLink’s are 25 times larger than they need to be. It also says that even if the system failed, and its dream of a million active SatPaqs came true, their transmissions would likely overlap with a fixed receiver only around once every 13 months, for just two seconds. Furthermore, Higher Ground plans to retain remote control over every SatPaq, with the ability to disable individual devices instantly following a report of interference.

Steve Crowley, a consulting wireless engineer, could find nothing to disagree with in an independent technical review of Higher Ground’s technology that confirmed its feasibility. “I am not persuaded SatPaq will be a significant problem for CenturyLink,” says Crowley. “It’s not perfect, but is there no risk of CenturyLink’s equipment failing itself?”

However, the microwave industry is worried that SatPaq’s databases could be inaccurate or out of date, that signals from multiple devices could combine dangerously, and that fixed stations would not even realize what was causing any resulting interference. “The transient nature of the mobile device makes the task of tracking down and confirming the source almost impossible,” wrote the FWCC. “Higher Ground could simply claim its protection mechanism operated flawlessly because there would be absolutely no way for a fixed station licensee to identify or locate the interference.”

On 23 February, Rob Reis met with CenturyLink engineers at their Denver office to try to reach a compromise. Although CenturyLink described the meeting as “friendly and productive”, the company came out of it still opposing a blanket license for SatPaq. “The system should be more fully vetted before it is implemented nationally,” it wrote in early March. “Higher Ground should perform testing to demonstrate the reliability of the interference protection scheme and … that the system effectively prevents interference when multiple SatPaqs are in use.”

Over the winter, Higher Ground tested around 20 SatPaqs in California and Washington DC. In March, it also received permission to test in New York City. It is now up to the FCC to decide whether or not to grant Higher Ground a blanket waiver to operate tens of thousands of SatPaqs commercially.

Steve Crowley thinks the prospects for Higher Ground are good: “The FCC sees spectrum sharing as increasingly the future, with the benefits of sharing outweighing the low risk of interference.”

CenturyLink even hinted that it might remove its objection—if Higher Ground shouldered all the risk. “The application should not be granted unless Higher Ground accepts liability for any harm to CenturyLink, its network, and any users of its network resulting from interference caused by SatPaq devices,” it wrote to the FCC in March. “If Higher Ground wants to launch a novel interference protection system and new devices in this band, Higher Ground should be willing to accept responsibility.”

If Higher Ground’s application is successful, SatPaqs could pave the way for other ground-breaking spectrum-sharing technologies. The battle for America’s microwaves could soon be heating up.

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