FCC Urged to Adopt Indoor 911 Z-Axis Accuracy Standard

A technology vendor and a locality have urged the FCC to adopt a 911 Z-Axis indoor location accuracy standard that is more precise than one proposed by national wireless carriers.

The comments were filed in PS docket 07-114 in response to an industry proposal for a z-axis, or vertical, standard submitted in August.

In the industry proposal, which was submitted by an FCC-mandated deadline that was set in a 2015 order (TR Daily, Jan. 29, 2015), the carriers recommended a z-axis metric “of +/- 5 meters for 80% of fixes from mobile devices capable of delivering barometric pressure sensor-based altitude estimates” (TR Daily, Aug. 7).

The industry proposal was included in a cover letter to a report on the results of indoor location accuracy testing conducted by a test bed established by CTIA on behalf of the industry. The report recommended additional testing.

Yesterday, as TR Daily reported (TR Daily, Oct. 1), public safety entities filed comments expressing their opposition to the z-axis standard proposed by the carriers and pushing for a more precise metric. In its comments, CTIA said the Commission should not adopt the standard and should instead allow the industry to conduct further testing.

In its comments yesterday, NextNav LLC, one of two vendors whose technology was tested in the test bed established by CTIA, said that “The Stage Z test bed provided the fourth opportunity for NextNav to demonstrate that its Metropolitan Beacon System (‘MBS’) technology provides vertical location accuracy of within 3 meters for at least 80 percent of wireless calls to E911 emergency services. Specifically, the Stage Z Report indicates that NextNav’s MBS technology was accurate within 1.8 meters across all three morphologies tested.”

“Given the demonstrated capabilities of NextNav’s MBS technology, combined with the test results of another vertical location technology vendor [Polaris Wireless, Inc.], the Commission should immediately address the critical public safety concern identified by the first responder community by adopting a vertical location metric that truly reflects ‘floor level’ accuracy, i.e., +/-3 meters for 80 percent of wireless calls to E911,” NextNav added. “The Commission should reject the request of the major wireless carriers for a vertical location metric of +/-5 meters. Such a metric is not necessitated by the Stage Z test data and would not provide the floor level accuracy that both the wireless carriers and the Commission committed to achieving in the carriers’ Roadmap and in the Commission’s 2015 Fourth Report and Order.”

NextNav continued, “The Stage Z test process provided sufficient information for the Commission to adopt a z-axis metric of +/-3 meters. As the Stage Z Report acknowledges, the vertical location tests were conducted in a ‘reasonably comprehensive’ selection of regions, buildings, test points and weather conditions and no material variations in performance were identified. The test set up reflected real world conditions, using a variety of handsets and operating systems, including both older and newer devices. The barometric pressure sensors contained within those handsets are commercially available and widely used by manufacturers, having been installed in the handsets by the device manufacturers and therefore were never touched by any entity involved in the test process.

“No further vertical location testing is needed before the Commission adopts its z-axis metric,” the vendor added. “In fact, any significant delay in the adoption of the metric could harm public safety by placing into question the ability of the major wireless carriers to implement vertical location solutions in the top 25 and 50 census metropolitan areas by the respective 2021 and 2023 deadlines.

“This said, NextNav agrees with the carriers that further z-axis testing should be conducted, particularly to assess the capabilities of new vertical location technologies as they are made available by other vendors,” the filing said. “Such z-axis testing will need to consider the specific variables and uncertainties that are presented by such location technologies. Thus, just as the testing of barometric sensor technologies considered variations in outdoor and indoor air pressure, the testing of location technologies that rely on registered databases of consumer devices (such as Wi-Fi and Bluetooth) will have to consider variations in the density and transmission characteristics of such devices in different types of buildings and socioeconomic conditions.”

In its comments, Boulder, Colo., Emergency Telephone Service Authority (BRETSA) said, “NextNav has demonstrated in the Test-Bed that it can reliably achieve z-axis accuracy of +/- 2-meters for 80 percent of calls (‘two-meter accuracy’).”

“The two-meter accuracy metric should thus apply only in markets in which a Location Provider’s infrastructure has been deployed and a proof-of-performance completed showing that the technology is capable of meeting that level of accuracy,” BRETSA added. “If modification of the infrastructure is required to achieve two-meter accuracy, Carriers should (i) only be required to comply with the actual level of accuracy achieved in proof-of-performance testing until the Location Provider is able to meet the two-meter accuracy requirement, and (ii) advise affected PSAPs of the actual level of accuracy provided so that First Responder operating procedures can be adjusted as appropriate. A time-limit for compliance with the two-meter standard should be adopted.

“There may be markets where Location Providers will be unable to deploy their location technology (due to a lack of radiofrequency licenses, for example), or the number of multi-story buildings, population and related characteristics of a market are such that deployment of a location technology is unnecessary or uneconomic,” the filing added. “PSAPs serving suburban or rural areas adjacent to densely urbanized areas, and located outside of the area in which location technology is deployed, may nevertheless receive z-axis data which is less accurate than that provided within the densely urbanized area, and which First Responders find useful. The metric applicable to the areas served by these PSAPs should be that actually achieved in proof-of-performance testing, without penalty, unless a PSAP is able to demonstrate a need for more accurate data justifying the investment in deployment of additional location infrastructure.”

BRETSA also said that “Carriers and Location Providers should be required to publish procedures for PSAPs or other public safety entities to test vertical location accuracy within the PSAP’s or entity’s jurisdiction, or even with respect to specific buildings within such jurisdictions as part of preparation of Emergency Response pre-plans. These published procedures should include a description of any actions or cooperation required of the Carrier and Location Provider to complete the tests, the manner in such action or cooperation is to be requested, and the commitment of the Carrier and Location Provider to take such action or provide such cooperation.”

It also said that “[a] Location Provider and the Carriers should be granted a waiver in any instance in which the Location Provider is unable to achieve two-meter z-axis location accuracy within a market area (densely urbanized area) after reasonable effort and investment. The grant of such waiver(s) should be considered in assessing whether the Location Provider should remain on the list of Location Providers which have demonstrated in the Test-Bed that they are capable of meeting the two-meter accuracy metric. Where a Location Provider and Carriers have been granted a waiver, the required accuracy should be that demonstrated through proof-of-performance in the market.” —Paul Kirby,paul.kirby@wolterskluwer.com

Courtesy TRDaily