911 tech pinpoints people in buildings—but could disrupt wireless ISPs

Cell phones replacing landlines are making it difficult to accurately locate people who call 911 from inside buildings. If a person having a heart attack on the 30th floor of a giant building can call for help but is unable to speak their location, actually finding that person from cell phone and GPS location data is a challenge for emergency responders.

Thus, new technologies are being built to accurately locate people inside buildings. But a system that is perhaps the leading candidate for enhanced 911 geolocation is also controversial because it uses the same wireless frequencies as wireless Internet Service Providers, smart meters, toll readers like EZ-Pass, baby monitors, and various other devices.

NextNav, the company that makes the technology, is seeking permission from the Federal Communications Commission to start commercial operations. More than a dozen businesses and industry groups oppose NextNav (which holds FCC licenses through a subsidiary called Progeny), saying the 911 technology will wipe out devices and services used by millions of Americans.

Harold Feld, legal director for Public Knowledge, a public interest advocacy group for copyright, telecom, and Internet issues, provided the best summary of these FCC proceedings in a very long and detailed blog post:

Depending on whom you ask, the Progeny Waiver will either (a) totally wipe out the smart grid industry, annihilate wireless ISP service in urban areas, do untold millions of dollars of damage to the oil and gas industry, and wipe out hundreds of millions (possibly billions) of dollars in wireless products from baby monitors to garage door openers; (b) save thousands of lives annually by providing enhanced 9-1-1 geolocation so that EMTs and other first responders can find people inside apartment buildings and office complexes; (c) screw up EZ-Pass and other automatic toll readers, which use neighboring licensed spectrum; or (d) some combination of all of the above.

That’s not bad for a proceeding you probably never heard about.

All eyes on the FCC

While the Progeny proceeding has flown under the radar, the FCC may be inching toward a decision. The FCC's public meeting next Wednesday will tackle the problem of improving 911 services. Feld says the FCC seems to be close to making a decision, although the FCC itself did not respond to our requests for comment this week. All the public documents related to the proceeding are available on the FCC website.

"The FCC appears poised to completely disregard technical reality."

NextNav's website says the company "was founded in 2007 to solve the indoor positioning problem." But it has no revenue today, and it won't unless the FCC approves its application or it finds another line of business.

The Wireless Internet Service Providers Association (WISPA) is worried that the FCC will rule in Progeny's favor, despite tests that WISPA and others believe prove Progeny service would degrade performance of many existing devices or render them unusable altogether.

"The FCC appears poised to completely disregard technical reality, disregard the record in their own proceeding and give final approval to Progeny to do something that's going to be very disruptive to the band that's been in use for 20 years harmoniously by millions of users," Jack Unger, WISPA's technical consultant, told Ars.

The band in question is 902-928MHz. This band is similar to Wi-Fi in that it permits many unlicensed uses such as the ones mentioned earlier in this article. It also permits a select few licensed uses, including Progeny's M-LMS (Multilateration Location and Monitoring Service), which forms the backbone of its enhanced 911 service.

NextNav has already set up a network of roughly 60 transmitters to cover a 900-square-mile area including San Francisco, Oakland, and San Jose, NextNav CEO Gary Parsons told Ars in a phone interview. NextNav has begun deployments in the rest of the top 40 markets in the country, but the Bay Area is the only one fully built out.

NextNav's marketing pitch.

Credit: NextNav

"We've been actually broadcasting in the San Francisco and Silicon Valley area now, portions of it, for over three years," Parsons said. NextNav has FCC licenses allowing it to transmit, but it needs a further approval in order to begin commercial operations, he said.

Progeny technology may not solve the 911 problem

"If you're trying to send someone to a heart attack victim, you better hope they can tell you where they are."

In order to work, the GPS chips in the next generation of cell phones would need to be slightly modified to allow communication with the Progeny network. That's just a software upgrade, but one that has to be done prior to a phone being built, Parsons said.

Why is this necessary? GPS is good at locating people outside, but not indoors, Parsons said. "What we bring to the party is a location accuracy that is much more precise than that which is currently available, with the ability to identify vertically what floor you're on," Parsons said. "It's one thing knowing what block you're in, but if you're trying to send someone to a heart attack victim on the 89th floor of the Chrysler Building in New York, you better hope they can tell you where they are."

Results for the Progeny system are promising, but perhaps not enough so to declare it a winner. An FCC advisory committee known as CSRIC (Communications Security, Reliability, and Interoperability Council) gave Progeny high marks compared to contenders Qualcomm and Polaris in a report dated February 19, 2013. (Unger provided a copy of this report to Ars.)

Progeny claims horizontal accuracy to within 20 meters and vertical accuracy to within 2 meters. But the CSRIC report said that even today's best technology consistent enough.

"[P]rogress has been made in the ability to achieve significantly improved search rings in both a horizontal and vertical dimension," CSRIC wrote. "However, even the best location technologies tested have not proven the ability to consistently identify the specific building and floor, which represents the required performance to meet Public Safety's expressed needs. This is not likely to change over the next 12-24 months. Various technologies have projected improved performance in the future, but none of those claims have yet been proven through the test bed process."

One set of test results, interpreted in many different ways

NextNav and its opponents collaborated on a series of tests to determine how the Progeny system would interact with WISP signals and smart meters. The test results were released last October. The numbers themselves aren't in dispute, but each side interprets them very differently.

Among Progeny's opposition is the Part 15 Coalition (Part 15 of the FCC rules regulate the operation of low power devices on unlicensed spectrum). Besides those already mentioned, Part 15 technology includes devices that monitor safety of gas and oil pipelines, hearing aids, Plantronics headsets, and emergency response devices made by Inovonics, said Henry Goldberg, counsel for the Part 15 Coalition.

Goldberg told Ars that the Progeny system has an 80 percent duty cycle (meaning it operates 80 percent of the time), and that Progeny's 30-watt transmissions would overwhelm the 1-watt transmissions used by numerous Part 15 devices.

This is one example of where the two sides interpret the same results differently. Parsons said each Progeny transmitter operates only 10 percent of the time, explaining that the 80 percent figure is true only when you add up the transmissions of devices within range of each other.

"What [Progeny opponents] generally fail to note is the ones they are seeing that are far away have a very weak signal coming in," Parsons said. "They might see one or two strong ones and six more that are miles away and at a much lower intensity level."

Progeny operates on a total of 4MHz in the 902-928MHz band, roughly within 920-922 and 926-928, he said. Smart meters that periodically report statistics to utilities could occasionally miss one transmission due to interference from Progeny but get the data through the next time by hopping frequencies, Parsons said.

Smart meter maker Itron said in a recent filing that "Any radio receiver mounted outdoors is subject to multiple beacons, experiencing the effect of cumulative duty cycles which, as Itron has shown, would be 80-90% in densely deployed areas… testing shows that unlicensed devices cannot co-exist with the Progeny system on its frequencies, which means that, at the very least, Progeny’s operations will take away 4 MHz of spectrum from unlicensed use, that the compression effect will further degrade use of the remaining spectrum, and that some users will experience greater loss of the spectrum."

Unger believes the wireless Internet Service Providers are at the greatest risk of interference from Progeny systems. WISPs serve more than 3 million users nationwide, with perhaps a quarter of them on the 900MHz band, he said.

This service is primarily for rural areas where customers have no other options. WISP speed is already low, from 500Kbps to 3 or 4 Mbps, and at its worst, interference from Progeny could reduce download speeds by 47.9 percent and upload speeds by 41.5 percent, Unger said. Besides lower speeds, interference could result in lost connections, he said.

The interference isn't really that bad, Progeny says

Progeny put a more positive spin on those numbers in a filing. "In two of the co-frequency tests the BWA [broadband wireless access] throughput reduction did reach 47.9 and 49 percent," Progeny said. "Most of the co-frequency tests documented much lower levels of BWA throughput reduction, however, with two co-frequency tests documenting reductions of just 2.5 and 8.3 percent. In fact, when the two worst case outliers are excluded from the results, the average throughput reduction for even the co-frequency tests drops to 16.33 percent."

Unger said the WISPs 4-watt transmissions would be wiped out by Progeny's much stronger ones. The 30 watts used by Progeny is measured in ERP (Effective Radiated Power) whereas the WISP's 4 watts is measured in EIRP (Effective Isotropic Radiated Power). Ultimately, this means the WISPs use 4 watts compared to Progeny's 49.2 watts when measured on the same scale, Unger said.

Although Progeny uses just 4MHz of spectrum, it's placed in such a way as to wipe out two of the three usable channels in the 902-928MHz band, WISPA argued in its most recent filing:

Credit: Wireless Internet Service Providers Association

Progeny further counters that WISP equipment already has to avoid interference from other unlicensed devices, and that their networks could be designed to avoid interference from Progeny. "What the joint tests do show is that the impact of Progeny’s M-LMS network on BWA equipment is highly variable and can be affected significantly by the configuration of the BWA link, the choice and placement of antennas, and the proximity and direction toward Progeny’s M-LMS beacons," Progeny wrote. "The test results also demonstrate that the impact of Progeny’s M-LMS network on BWA equipment is only a small fraction of the degradation that BWA networks already routinely experience from other users of the 902-928 MHz band."

Parsons argued that the existence of Progeny's network in the Bay Area without any complaints proves that it can co-exist with unlicensed devices. "It's not like we're asking to light up a network," he said. "All of this interference potential that some of these parties are making political points about are not there in practical impact, because we've been operating for years."

Unger counters that while Progeny has operated, there could be interference that wasn't detected because Progeny didn't actually test for interference with existing devices except for when the FCC demanded it. Of course, Progeny's opponents believe those tests prove the network would disrupt devices in the band, and the opponents are numerous.

One Progeny, many opponents

Businesses and organizations filing opposition against Progeny or at least demanding further testing include Plantronics, Google, the Utilities Telecom Council, the Maryland Transportation Authority, National Association of Regulatory Utility Commissioners, smart grid company Landis & Gyr, Inovonics, the New America Foundation, the American Petroleum Institute., the Alarm Industry Communications Committee, several individual utilities, EZ-Pass, and others.

A few members of Congress have weighed in. US Rep. Anna Eshoo (D-CA) wrote favorably of Progeny's ability to improve 911 services but acknowledged that more work may be required to prevent interference with "other important spectrum users."

US. Sen. Maria Cantwell (D-WA) and Sen. Amy Klobuchar (D-MN) opposed Progeny's request for a waiver.

"There are like 60 companies saying to the FCC there is a real problem and Progeny is the only one saying there's no problem," Unger said. "I've never seen this kind of an unbalanced record before."

Goldberg said the Progeny proceeding reminds him of LightSquared, which wanted to build a nationwide LTE network but failed to gain FCC approval because of interference with GPS devices. Goldberg, who was counsel to Lightsquared in that case, believes the Progeny one could have a more favorable outcome for both sides if Progeny is willing to compromise.