Trial seeks to provide hard data to answer FCC's indoor-location questions

Nov 27, 2012

Trial seeks to provide hard data to answer FCC's indoor-location questions

A trial is underway in the San Francisco Bay Area that an FCC advisory committee hopes will provide definitive data regarding the optimal approach for locating emergency callers using wireless handsets inside buildings. The trial — which began on Nov. 15 and runs through Dec. 31 — was organized by the commission's Communications Security, Reliability and Interoperability Council (CSRIC).

Four organizations are participating in the trial: Polaris Wireless, Qualcomm, Boeing and NextNav. The San Francisco Bay Area was chosen for the trial because it provides all of the environments in which wireless phone subscribers typically operate: dense urban, urban, suburban and rural, according to Norm Shaw, Polaris's executive director of government affairs and business development. Shaw also is a CSRIC general delegate and co-chair of the group that is developing a report on indoor wireless E-911 location capabilities.

Speaking of that report, it originally was due to be submitted to the FCC in September, but a speed bump soon became obvious, Shaw said.

"The FCC is asking a lot of questions about indoor location … but we can't realistically tell them about indoor," Shaw said. "All of the vendors have their own claims and PowerPoint presentations on what they can and cannot do, but there is no data on location technology performance indoors upon which we can base any kind of recommendation to the FCC."

The trial is intended to overcome that hurdle by providing an objective test bed for evaluating various technologies under similar circumstances. Shaw believes that any recommendation will be a hybrid solution with Assisted GPS (AGPS) as the primary technology and something else as a backup, which is needed because AGPS doesn't perform well in complicated RF environments, Shaw said.

"AGPS is the premier location technology for open sky and more rural types of environments," he said. "But you run into problems with AGPS even before you go into a building when you're in a dense urban environment, such as an urban canyon environment like in Manhattan, because of all the multipath and non-line-of-site issues you have."

The big question is: what will be the secondary technology that will cover the areas where AGPS stumbles? According to Shaw, Qualcomm — which manufactures AGPS chips — will test its Advanced Forward Link Trilateration (AFLT) technology during the trial. While he believes that AFLT — a handset-based technology that does not rely on GPS satellites to determine location — will be compatible with AGPS, Shaw said that the technology will not work with asynchronous networks, such as those deployed by AT&T and T-Mobile, which is a limiting factor.

Meanwhile, Boeing, which has been operating and maintaining Iridium's constellation of low-Earth-orbiting satellites under a long-term contract, will test whether LEO-satellites — which operate at considerably higher power than other GPS satellites — will solve the indoor-location conundrum.

"What Boeing wants to show is that the added power from the low-earth-orbit satellites gives you a lot more punch in terms of what you can do with a GPS-like system, and that it will be better than AGPS," Shaw said. "But they're going to need to marry to some terrestrial technology, because they're not going to cover deep into buildings no matter what they do. Power is not going to overcome basic physics."

NextNav likely has a similar issue, according to Shaw. The principles of the company founded XM/Sirius satellite radio, and ultimately discovered that this network had quite a few coverage holes for the reasons cited above. To solve this problem, they deployed terrestrial radio towers that served as repeaters for the satellite radio signals. Shaw said that NextNav plans to demonstrate that by leveraging its existing satellite and terrestrial infrastructure it can create an indoor-location solution that will work in all environments. However, whether it will work will depend largely on the robustness of its terrestrial component. If it's not as robust as the cellular networks, NextNav is "going to have a hill to climb," Shaw said.

Shaw's company, Polaris Wireless, is relying on its RF pattern-matching technology, which is a network-centric approach that collects radio link measurements from the network and/or device, and then uses sophisticated algorithms to estimate the location of the user. According to Shaw, it works well in non-LOS environments, which makes it "almost perfectly symbiotic" with AGPS.

"Our particular interest in this test is that it will show in an independent way that this technology, when married to AGPS, provides sort of a global solution, something that works everywhere."

Regardless of how the trial turns out, Shaw is confident that it will provide the FCC with the answers it seeks.

"All of us at CSRIC are excited to see how this thing comes out," said Shaw, who added that the final report is expected to be delivered to the FCC in March.

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