All four nationwide wireless carriers—AT&T, Verizon, T-Mobile and Sprint—will add device-based hybrid (DBH) location technologies that are designed to improve wireless emergency-caller location information, even within buildings, but public-safety officials expressed concerns about efforts surrounding vertical-location data.

“Dialing 911 is likely the most important call you ever make, and the wireless industry’s adoption of DBH technologies will make it easier for first responders to find you indoors more quickly and accurately,” said Tom Sawanobori, senior vice president and CTO for CTIA, a key trade association for commercial wireless providers.

DBH solutions leverage a combination of available technologies—from satellite GPS to sensor data and crowd-source Wi-Fi—to determine a 911 caller’s location. This approach is similar to the one used by popular commercial ride-sharing and navigation applications, which typically provide much better location data than carriers provide to 911 centers today, particularly when a wireless caller is inside a building, where GPS signals may not reach.

Improving location accuracy for wireless 911 callers is a priority for public safety, as about 80% of 911 calls are made from wireless devices, according to statistics from the National Emergency Number Association (NENA). Without accurate and reliable location information, public safety’s response often is delayed or requires the utilization of more valuable resources than would be needed if the accurate location of an incident were provided.

“With nearly 200 million 911 callers per year relying on wireless devices, it’s essential that 911 professionals are able to quickly and accurately locate these mobile callers,” said NENA’s CEO Brian Fontes. “We applaud the wireless industry, device manufactures, and software engineers for coming together to enable these life-saving advances in location technology.”

In 2015, the FCC approved rules designed to improve indoor wireless location accuracy and establish a test bed to evaluate technologies that could be used to enhance location information. In addition to having carriers provide XY-axis coordinates with location data for indoor 911 calls, the FCC rules call for the development of technologies to determine a caller’s vertical location, or Z-axis information.

“DBH solutions have produced a reliable and accurate horizontal location in various types of buildings and across all morphologies during testing in the [911 Location Test Bed],” according to a CTIA press release.

But several public-safety officials on the governing board of the National Public Safety Telecommunications Council (NPSTC) expressed concerns about the accuracy goals included in an FCC filing about the test results of vertical-location technologies from NextNav and Polaris Wireless, the only two vendors that submitted Z-axis solutions for the test bed.

In a letter to the FCC dated Aug. 3, representatives from CTIA and all four nationwide wireless carriers stated that the vertical testing results “provide support for a metric of [plus or minus] 5 meters for 80% of fixes, [but] additional testing may yield results that validate adoption of a more accurate metric,” and asked the FCC to support further vertical-location tests during 2019.  The letter also noted that neither NextNav’s technology was not tested in rural environments or one of the urban cities, and the Polaris Wireless solution was not tested with Apple phones, so further testing would be needed.

NPSTC Executive Director Marilyn Ward said that vertical location with a potential error of plus or minus 5 meters would establish a range of about 32 feet, which would cover at least three floors of a high-rise building.