Locating a 911 caller

Jun 2, 2016   

Posted by Dave McHoul

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On a recent episode of “Last Week Tonight with John Oliver” on HBO, John presented a special report on the state of 911 location. While the report is sprinkled with John Oliver’s witty and humorous viewpoint on the subject, the underlying issue is very real and, ironically, has gotten worse as cellular technologies have improved.


Luckily, there is an answer to this problem that’s cost-efficient and can be implemented quickly.  But first the history…

 

The Original E911 Mandate

In the late 1990’s the United States Federal Communications Commission (FCC) issued the First Report and Order (aka the E911 mandate) that compelled U.S. wireless carriers to implement technology to locate people who called 911 from a mobile phone.  The major wireless carriers started to implement this technology in the early 2000s, with the smaller operators following suit shortly thereafter.

 

The FCC mandated a two-phased approach.  In Phase I, carriers were to provide only the lat/long of the Cell Site that served the call.  This was primarily used for routing purposes to ensure that the 911 calls were routed to the appropriate Public Safety Answering Point (PSAP).  In Phase II, the FCC strengthened the accuracy requirements as follows:

  • Handset-based methods: locate callers within 50 meters for 67% of the calls, within 150m for 90% of the calls
  • Network based methods: within 100m for 67%, within 300m for 90%

 

The handset-based method deployed by the major CDMA/IDEN carriers Verizon, Sprint and (at the time) Nextel, used Assisted Global Positioning System (A-GPS) technology.  The network-based method deployed by the TDMA (2G) and GSM (3G) carriers including Cingular (which later acquired AT&T and consolidated under the AT&T brand), AT&T and T-Mobile utilized Uplink Time Difference of Arrival (U-TDOA) technology.

 

Initially, the FCC required the carriers to self-report the accuracy of their selected location technology on a quarterly basis.  However, they did not stipulate the testing methodology and did not require that calls originating from indoor areas be included in the test results.

 

The Indoor Mandate

The illustration at the 4:30 point of the John Oliver report is a good example of the indoor problem.  In the video, the reporter calls 911 from inside the PSAP building but the operator conveys a location that is ¼ mile away. The call could not be located accurately because the A-GPS technology used to locate the caller does not work indoors – particularly not in fortified buildings in the basement where PSAPs are typically located.

 

In early 2013, the California chapter of the National Emergency Number Association (CALNENA) published research that spurred the industry to action. (CALNENA’s letter to the FCC is here).  After examining the data from 87,000 911 calls received in Ventura County, CA over an 18-month period, they found that more than half of the calls were delivering only Phase I (Cell Site ID) location.

 

Subsequent to the CALNENA reports, several other areas performed similar analysis, finding similar results.  After further analysis, the indoor limitations of A-GPS were found to be at the root of the problem.

 

As you can imagine, all of this activity and negative sentiment caught the attention of the FCC.  In early 2014, the FCC issued a notice of their intention to update the E911 mandate to include calls originating from indoor environments.

 

After roughly a year of comments by private and public stakeholders and proposals by industry associations, technology providers, and wireless carriers, the FCC issued the “Fourth Report and Order” (aka the Indoor E911 Mandate) in early 2015.  The requirements contained in the final report include:

  • Horizontal Location:  Nationwide US Carriers must provide either a dispatchable address, or locate calls originating from indoor environments within 50 meters for 40% of all wireless calls by 2017, ramping up to 80% by 2021.
  • Vertical Location: Carriers need to submit Z-Axis (vertical) metrics by 2018 and implement technology to meet those metrics by 2021 in the most populous markets.
  • Location Technology Testbed:  A testbed must be established and administered by a third party in which all proposed technologies will be evaluated and validated prior to deployment.

 

While the mandate represents a positive step, there remain some potential shortcomings in the chosen approach.  For example:

  • The horizontal accuracy requirements include all wireless calls, so outdoor and indoor results can be blended.
  • The vertical requirements do not define the accuracy specifications, but instead reflect a commitment to develop metrics and try to me meet those metrics in the future.
  • Providing a dispatchable address is an elusive requirement that is ambiguous in its interpretation – is it “a” dispatchable address, or “the” dispatchable address?

 

Credit where it’s due

However, while much of the attention received today regarding 911 location is negative, it is worth noting that 911 location technologies have saved many lives throughout its fifteen-plus year history.  In fact, the US is the only country in the world with a real mandate to locate distressed wireless callers.  Europe for example has only a best effort clause.

 

Notable stories exist of 911 location capabilities include rescuing an abducted corrections officer or a kidnapped woman, and even helping to locate the Boston Marathon Bomber.

The PBS show Nova aired a special on May 29, 2013 titled “Manhunt—Boston Bombers.  Which technologies worked—and which didn't—in the race to track down the men behind the marathon attack?”  The Nova special recounts the story of how the driver of the car that was hijacked by the bomber dialed 911 and left the line open, enabling authorities to home in on their position.

 

Skyhook’s Precision Location provides better location accuracy

Fortunately, Skyhook’s Precision Location technology -- which combines GPS, cell and Wi-Fi location measurements -- can help solve the location accuracy problem and meet the FCC’s mandate today.

 

As part of the initial evaluation during the comment period for the Indoor Mandate, the FCC established a working group within the existing Communication, Security, Reliability and Interoperability Council (CSRIC) to evaluate the ability of certain technologies to meet any proposed requirements.  Skyhook’s Precision Location solution was tested as part of this initiative, then subsequently tested in accordance with the CSRIC guidelines.   

To summarize the results, the testing indicates that the Skyhook solution locates 80% of indoor wireless calls within a 50 meter radius in dense urban and urban environments and a hybrid Wi-Fi / Assisted Global Positioning System (A-GPS) solution performs equally well in urban and suburban morphologies. In fact, blending Wi-Fi results with the high-accuracy locations that are typically observed outdoors using A-GPS can provide accuracy below the 50m threshold, even at the 80th percentile.


Many apps, devices, and adtech providers currently use Skyhook to provide the most accurate and precise location services available. It’s essential for E-911 location services to have the same cutting-edge technology available in the moments when it’s needed the most.

 

Download Skyhook Precision Location SDK

Topics: Devices, location