Roam-eo, Roam-eo, Wherefore Art Thou? Locating E911 Callers to Become Easier

With widespread cooperation, Commission looks to improve accuracy, reliability of E911 location capability

Back in the day, when landline phones ruled, emergency responders could locate 911 callers with relative ease. After all, each landline phone was tied to a specific, readily identifiable address (and often a specific office at that address), so when a call came in, it was easy to pinpoint the originating address.

Then came wireless phones, and locating the emergency caller got trickier: an E911 message originating from a wireless phone could be coming from just about anywhere. Initially, the FCC mandated that carriers be able to provide Public Safety Answering Points (PSAPs) the location of an E911 caller to within 50 to 300 meters (depending on the technology used). But that requirement applied only to calls originating outdoors, and it mandated provision of only horizontal locations determined by geographic coordinates (i.e., latitude and longitude). What about wireless 911 callers who happened to be indoors or, worse, on an upper story in a high-rise?

As we reported, last year the FCC launched a proceeding looking to improve E911 location capability for just such circumstances. And now, in the wake of an impressively cooperative response to the Commission's proposals, the FCC has adopted a Fourth Report and Order (4th R&O) establishing a new set of E911 location standards. Set to take effect gradually over a period of several years, the new standards reflect the seemingly universal acknowledgement that the ability of emergency responders to locate E911 callers quickly is a matter of utmost importance.

Historically, the FCC's location requirements have been based on the determination of the wireless phone's geographic coordinates (i.e., latitude and longitude, a/k/a the x- and y-axes). Last year's proposal stuck with that approach, but included a third-dimension (the so-called z-axis) to reflect the caller's vertical location, an essential datum for locating callers in a multi-story structure. The Commission recognized that reliance on a system that could generate a "dispatchable address" directing responders to a specific location would be preferable to the less specific x/y (or x/y/z) approach, but it viewed such a system as more of "long-term objective". What a difference a year makes!

As it turns out, the proliferation of various in-building technologies - small cells, Wi-Fi and Bluetooth beacons - has given rise to the possibility that an extensive, reliable database of dispatchable addresses can be compiled and integrated into the E911 system. (For these purposes, a "dispatchable address" includes street address and additional information - floor, suite number, apartment number, etc. - necessary to identify the calling party's location.) So the new rules include as one alternative the provision of dispatchable addresses, as that capability develops. Reliance on x-, y- and z-axis determinations remains another alternative.

As to that latter alternative, more work still needs to be done with respect to vertical, or z-axis, determinations. The information that permits such determinations comes from barometric sensors included with an increasing number of handsets. The changes in barometric pressure registered by those sensors can be used to calculate how high above ground the sensor is. But the raw data from the handset may need to be calibrated to some degree to assure its accuracy. As a result, the new rules afford carriers additional time to come up with an appropriate metric for z-axis accuracy and then to satisfy that standard.

The new rules provide two sets of implementation schedules, one applicable to horizontal locations (x- and y-axis), the second to vertical (z-axis) determinations. As to horizontal locations, all CMRS providers will have to provide to PSAPs either the (1) dispatchable location, or (2) the x/y location within 50 meters, for the following percentages of wireless 911 calls within the following timeframes:

• Within two years of the rules' effective date: 40%;
• Within three years: 50%;
• Within five years: 70%;
• Within six years: 80%.

Non-nationwide CMRS providers (regional, small, and rural carriers) can extend the five- and six-year deadlines based on the timing of Voice over Long Term Evolution (VoLTE) deployment in their networks.

As for vertical (z-axis) determinations, CMRS providers must meet the following requirements with respect to wireless 911 calls (all timeframes start as of the rules' effective date):

• Within three years: All CMRS providers must make available to PSAPs uncompensated barometric data from any handset that has the capability to deliver barometric sensor data;
• Within 3 years: Nationwide CMRS providers must use an independently administered and transparent test bed process to develop a proposed z-axis accuracy metric, which must be submitted to the Commission for approval;
• Within 6 years: Nationwide CMRS providers must deploy either (1) dispatchable location, or (2) z-axis technology that achieves the Commission-approved z-axis metric, in each of the top 25 Cellular Market Areas (CMAs);
• Within 8 years: Nationwide CMRS providers must deploy dispatchable location or z-axis technology in accordance with the above benchmarks in each of the top 50 CMAs.

Non-nationwide carriers that serve any of the top 25 or 50 CMAs will have an additional year to meet these benchmarks.

Compliance will be determined by reference to quarterly live 911 call data reported by CMRS providers in six cities (San Francisco, Chicago, Atlanta, Denver/Front Range, Philadelphia, and Manhattan Borough, New York City) and their surrounding areas. (According to the Commission, these cities are representative of dense urban, urban, suburban, and rural areas nationally.) For purposes of determining compliance, carriers must generate a location fix within 30 seconds for a 911 call to be counted towards compliance with existing location accuracy requirements.

The quarterly reporting in those six cities will begin no later than 18 months from when the rules takes effect. Within that same timeframe, CMRS providers in those cities will also start providing more "granular" quarterly data for evaluation of the performance of particular location technologies within different morphologies (e.g., dense urban, urban, suburban, rural). These more granular data will be used solely for evaluation, not for compliance determinations. Nationwide CMRS providers will also have to report on their initial plans for implementing improved indoor location accuracy and on the progress of that implementation.

The Commission has also decided to tweak the "confidence and uncertainty" (C/U) data requirements. The rules have previously required carriers to provide PSAPs with C/U data at the request of the PSAP. C/U data reflect "the degree of certainty that a 911 caller is within a specified radius of the location provided by the CMRS provider". For example, a C/U "score" or 90%/35 meters means that there is 90% confidence that the caller is within 35 meters of the estimated location. The scoring provides PSAP call-takers the ability to gauge the reliability of any incoming location designation.

Because carriers' reports have historically relied on varying certainty percentages, the utility of their data has been reduced. To correct that, the Commission has decided to require that C/U data be provided on a per call basis (at the request of the PSAP) with a uniform confidence level of 90%. The Commission is also beefing up CMRS providers' data collection and retention obligations as well as their obligations to provide those data to PSAPs at the PSAPs' request.

The 4th R&O contains considerable detail that should be considered by CMRS providers and PSAPs alike. Viewed from 30,000-foot level, it reflects a consensus among all interested parties that the accuracy and reliability of E911 information is of overriding importance. Indeed, the approach adopted by the FCC has been shaped in large measure by two separate initiatives undertaken in response to last year's Notice of Proposed Rulemaking. On the one hand, the Association of Public-Safety Communications Officials, the National Emergency Number Association and the four national wireless CMRS providers joined together to produce a "Roadmap for Improving E911 Location Accuracy". On the other, the Competitive Carriers Association submitted its own "Parallel Path for Competitive Carriers' Improvement of E911 Location Accuracy Standards". While the two varied in a number of respects, together they formed the "essential foundation" for the 4th R&O.

The new E911 location accuracy rules are set to take 30 days after publication in the Federal Register, which will start the implementation schedules described above. Also, some of the new rules are "information collections" that will have to be run past the Office of Management and Budget for Paperwork Reduction Act purposes; we'll have to look for further notices announcing their effectiveness. Check back here for updates.