Wireless Carriers Want Phased-In 3-Meter Z-Axis Accuracy, No Floor-Level Data
Friday, June 28, 2019 | Comments

Wireless carriers voiced concerns with providing floor-level data for 9-1-1 calls from indoor multistory locations and urged the FCC to adopt a phased approach for 3-meter Z-axis location accuracy requirements.

The concerns were part of reply comments filed in response to the FCC’s proposed March rules that side with public safety and would require a vertical (Z-axis) location accuracy metric of ±3 meters relative to the handset for 80 percent of indoor wireless 9-1-1 calls. The new rules will help first responders more accurately locate people who make wireless 9-1-1 calls from multistory buildings.

AT&T argued against requiring floor-level data and agreed with Google that the FCC use a timetable for increasingly demanding Z-axis call coverage and/or geographic coverage requirements. “Given the variances in building structural characteristics and terrain, AT&T continues to believe that imposition of a floor level data requirement is infeasible at this time,” AT&T said.

In its earlier comments, AT&T supported establishing a 3-meter Z-axis location metric. However in its reply comments, the carrier said: “Proven solutions that meet this metric are not currently available, and thus the commission should consider a phased-in approach for implementation, which will allow market innovation to continue while also providing first responders with actionable information in the near term. … Device-based solutions show promise in advancing the evolution to dispatchable location. AT&T anticipates leveraging these technologies, but additional development is needed.”

T-Mobile USA’s reply comments said a phased-in approach based on PSAP readiness would allow carriers to focus their Z-axis development efforts in those areas where PSAPs are able to accept and use Z-axis information.

T-Mobile USA’s reply comments also agreed with Verizon’s comments on geographic areas. “Verizon suggests that the commission should focus its compliance benchmarks on those areas with the most critical need for Z-axis information with 9-1-1 calls — specifically, urban and dense urban morphologies,” T-Mobile said in its reply comments. “T-Mobile encourages the commission to explore this proposal …”

CTIA said in reply comments that “the commission should recognize that there was broad support for setting a ± 3-meter Z-axis metric as an important target, but the record demonstrates that validating whether this metric is achievable in the near-term requires further testing.” The group also said the FCC should require providers to deliver Z-axis vertical location data as an altitude level and not as floor level information at this time.

“Finally, contrary to the arguments made by the Boulder Emergency Telephone Service Authority (BRETSA), the Texas 9-1-1 Alliance, the Texas Commission on State Emergency Communications, the Municipal Emergency Communication Districts Association, and others, a more targeted metric than 3 meters is not feasible at this time,” CTIA said.

Alternatively, public-safety groups that included the International Association of Chiefs of Police (IACP), National Association of State EMS Officials (NASEMSO) and the National Sheriffs’ Association (NSA) urged the FCC to adopt the 3-meter vertical metric and narrow the metric in five years.

“… The commission has no choice but to immediately adopt a 3-meter metric for vertical location accuracy and require wireless carriers to implement this requirement, or a dispatchable location solution, in the largest 25 cellular market areas (CMAs) by April 2021 and in the top 50 CMAs by April 2023,” the International Association of Fire Fighters (IAFF) said in its comments.

NextNav and Polaris Wireless, two providers of location accuracy technology that participated in testing with CTIA, agreed a 3-meter Z-axis metric should be adopted right away.

In its reply comments, BRETSA, a 9-1-1 authority in Colorado, said the FCC should adopt a vertical location accuracy standard of 2 meters in urbanized markets and 3 meters in the rest of the country, which vertical location providers have demonstrated is achievable.

The Association of Public-Safety Communications Officials (APCO) International did not file reply comments. However, in its May comments, APCO called on the FCC to refrain from adopting a Z-axis metric and mandate instead that wireless providers deploy dispatchable location solutions only. APCO said that if the FCC retains the Z-axis approach, any metric adopted should include floor-level information.

For its part, Precision Broadband agreed with APCO that the proposed Z-axis metric of 3 meters must include a floor number. The company said the definition of dispatchable location should be changed from the current National Emergency Address Database (NEAD) to encompass other location databases.

Charley Simon, founder of Precision Broadband, said the company has demonstrated connecting its technology through interfaces with a rural internet service provider (ISP). When a mobile phone is connected to a broadband network with the Precision Broadband technology at the time a 9-1-1 call is made, the PSAP system would receive a dispatchable location — civic address, floor and unit — just like with a landline telephone, as well as a Z-axis barometric pressure provided altitude from another source such as Polaris Wireless, and an assisted-global navigation satellite system (GNSS) location point from a wireless carrier’s network. The 9-1-1 telecommunicator would have access to all readings, and either the PSAP technology or the PSAP telecommunicator would determine the best starting point for location.

The National Emergency Number Association (NENA) walked back some points of its original comments, saying its concerns about the NEAD should not be interpreted as a call for abandoning the program. In addition, NENA said it didn’t mean to suggest that a first responder should not be dispatched to a dispatchable location if that is best for operational needs. The association stood by its assertion that mobile providers deliver a location object (LO), formatted to be compatible with prevailing standards, to public-safety answering points (PSAPs).

Comments on the NEAD from NCTA, the Internet and Television Association, said resources may be better spent on alternative solutions that better boost location accuracy for 9-1-1 callers than the NEAD. NCTA said its members have challenges in working with CTIA to engage in testing of the database.

NCTA members have significant concerns about the NEAD’s effectiveness generally compared with more recent promising technologies, the cable industry’s ability to populate the NEAD with meaningful data, and the potential unintended negative effects on NCTA members’ customers, the group said in its reply comments.

All the reply comments are available here.

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On 7/25/19, Arthur Miller said:
Media keeps mentioning Polaris in the same league as NextNav for location-based service, which is not the case. Anyone who reviewed the FCC 2D and Z-axis test beds know that NextNav dominated the results, and Polaris just uses a software smoke-and-mirrors solution that would fail miserably if used at scale. Hopefully the media gets wise to this.


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