Report Says More Work Needed on Dispatchable Location Database, Public Safety Voices Concerns
Tuesday, May 07, 2019 | Comments

Only 38.7% of valid test calls conducted during recent dispatchable location testing for 9-1-1 calls produced a result that meets the requirements for actionable dispatchable location as defined by Alliance for Telecommunications Industry Solutions (ATIS) standards. Dispatchable location testing in the E9-1-1 Location Technologies Test Bed was conducted during the second half of 2018.

The reference point density in the National Emergency Address Database (NEAD) database is not yet at sufficient levels to assure optimum performance, according to conclusions in a report on the testing filed by CTIA with the FCC.

Low reference point density was found to cause instances where erroneous civic address details were reported, incorrect street addresses of neighboring buildings were reported, or no civic addresses were reported at all, which are reflected in the metrics.

However, the testing also showed that higher NEAD database density can likely significantly improve performance. Analysis based on the data gathered suggests that a NEAD database provisioning density higher than 50%, possibly in the 50% to 75% range, would likely translate into significantly improved overall performance in medium and large structures. A target provisioning density of 100% would be more appropriate for single family homes and stand-alone structures, unless assisted-GPS (A-GPS) geodetic fixes — not hybrid fixes relying on Wi-Fi — can be used as an effective cross-check to avoid dispatchable location results with erroneous civic addresses, the report said.

The report, titled “E911 Location Test Bed Dispatchable Location Summary Report,” uses two definitions for dispatchable location, a process public-safety groups have roundly criticized.

In the report, dispatchable location level 1 (DL1) refers to “medium-level performance. DL1 indicates that the reported dispatchable location is known to the quadrant or zone of the building on the correct floor or on the floor immediately above or below the correct floor.” Dispatchable location level 2 (DL2) refers to “the highest level of performance. DL2 indicated that the report dispatchable location is known to the specific unit number.”

“DL Level 1 is not consistent with the definition in the commission’s rules and is unacceptable from a public-safety standpoint,” the National Public Safety Telecommunications Council (NPSTC) said last year. “Furthermore, having these two definitions is likely to create confusion. NPSTC therefore urges the commission to maintain its current definition of dispatchable location, regardless of any apparent attempts by carriers to dilute that definition.”

“We support the distinctions of DL1 and DL2 for purposes of testing and developing new classes of service for emergency communications centers," said Jeffrey Cohen, chief counsel and director of government relations for the Association of Public Safety Communications Officials (APCO) International. "However, our position continues to be that only DL2 would qualify for purposes of compliance with FCC requirements. Dispatchable location is the gold standard for 9-1-1 indoor location accuracy, meaning the door to kick down.”

Jim Goldstein, director of government relations for NPSTC, agreed with Cohen that DL2 meets public safety's requirement to provide "the door to knock down to find the caller," but reporting "DL1 to the FCC was unacceptable as meeting DL. CTIA and the carriers heard us and then proceeded to have ATIS do it the way they have with two levels of DL. We do not agree that doing this meets the FCC order," he said.

Roger Hixson, 9-1-1 services senior consultant for the National Emergency Number Association (NENA), said he has a bit of a problem with the wording of the DL1 definition but didn’t provide specifics.

Only five Google Android mobile device models were tested because they are the only devices so far that support the necessary reporting and signaling needed to enable dispatchable location. iOS devices do not support the necessary functionality, and thus could not be used in the tests.

Testing occurred in two regions of the country – in and around Atlanta and San Francisco – in 25 buildings within four morphologies, from 230 test points, following the guidelines established in the ATIS- 0500035 standard. And 30,090 simulated 9-1-1 calls were made from 24 test devices.

The report said 82.6% of valid test calls resulted in some kind of civic address delivered, be it correct or incorrect. This metric is somewhat analogous to yield in geodetic positioning systems. Inversely, 17.4% of valid test calls produced no civic address. In addition, 74% of valid test calls produced a correct street address and 8.6% of valid test calls produced an incorrect street address — an address of a neighboring building.

Walt Magnussen Jr., who runs the Internet2 Technology Evaluation Center (ITEC) lab at Texas A&M University, said that with the ultimate goal being an X, Y and Z coordinate location with an accuracy level of 1 meter, the concept of defining accuracy in terms of unit, building quadrant or building seems to add to the confusion, rather than clearing anything up.

"Overall the report tells me that while the NEAD concept is valid, it has a ways to go," he said. "The report seems to indicate that the most pressing issue is that the density of reported access points is nowhere close to being sufficient. Since only service providers are required to register,  I doubt that we can ever get where we need to be. Since the FCC does not regulate the enterprise and since the enterprise owns the lion’s share of access points, there is no way to regulate the increase. On the other hand, were the FCC to facilitate a voluntary opt-in process, that would increase the safety of enterprise constituents, and it would be my guess that there would be a high take rate."

"Back in 2014 – 2015, public safety had concerns of how successful the NEAD would be, and this report does not do anything to alleviate those concerns," NPSTC's Goldstein said. "While the report does not say it directly, it seems that the carriers want more testing. It has been four years since the order and DL was promised as the gold standard, which replaced many of the more stringent requirements proposed by the FCC but not included in the final order based on the promise of DL.

"This makes it even more important to have the Z-axis. The carriers are relying on commercially available technologies such as Wi-Fi. It appears there are other technologies that are available be used to supplement Wi-Fi, but those may only provide the location of a caller and will cost the carriers addtional funds."

The full report is here.

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