9-1-1 Location: We Need to Do Better for Public Safety
By Andrew M. Seybold
Monday, December 02, 2019 | Comments
“Location, location, location” applies to the world of public safety as well as the real-estate industry. Location plays a vital role in many aspects of public safety’s daily responsibilities. It is important to know both the location of a 9-1-1 caller and the location of the incident being reported. When dispatched, first responders need to know the location of the incident, and when on the scene, they need to locate citizens who might be trapped in a building or otherwise need to be guided to safety. Finally, while first responders search for people and pets, the incident commander, at minimum, needs to be able to track locations of the responders.

This last point is critical to the safety of the first responders. In the open at an automobile accident, responders are probably in sight of the incident commander. However, inside a building, especially one with multiple floors, there is no way to know exactly where they are unless they verbally communicate their location. Add in smoke, flames and not knowing the building layout and it is easy to imagine delays in reaching citizens and first responders needing assistance.

I have been tracking the progress of location-based services for many years, and in November 2015, I wrote a white paper for NextNav, a location services vendor. NextNav uses one of the FCC-specified ways to determine height above street level (the Z-axis). When added to X and Y location coordinates, knowing the Z-axis will help locate citizens and first responders in a building.

In 2015, the FCC published a set of guidelines for location services. Under those rules, all cellular providers must provide a dispatchable location or X,Y locations within 50 meters, for the following percentages of wireless 9-1-1 calls within the following timeframes, measured from the effective date of the order:
• Within two years: 40% of all wireless 9-1-1 calls
• Within three years: 50% of all wireless 9-1-1 calls
• Within five years: 70% of all wireless 9-1-1 calls
• Within six years: 80% of all wireless 9-1-1 calls

Under the rules, all commercial providers must also meet the following requirements for provision of vertical location information with wireless 9-1-1 calls, within the following timeframes measured from the effective date:
• Within three years: All providers must make uncompensated barometric data available to public-safety answering points (PSAPs) from any handset that has the capability to deliver barometric sensor data.
• Within three years: Nationwide providers must use an independently administered and transparent test bed process to develop a proposed Z-axis accuracy metric and must submit the proposed metric to the FCC for approval.
• Within six years: Nationwide providers must deploy either dispatchable location or Z-axis technology that achieves the FCC-approved Z-axis metric, in each of the top 25 cellular market areas (CMAs). In areas where dispatchable location is used, the National Emergency Address Database (NEAD) must be populated with a total number of dispatchable location reference points in the CMA equal to 25% of the CMA population, and where Z-axis technology is used, commercial radio service (CMRS) providers must deploy Z-axis technology to cover 80% of the CMA population.
• Within eight years: Nationwide commercial 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.

Since then, both official and unofficial tests have been run, and vendors have set out to address these requirements in a variety of ways, including the NEAD, crowdsourced Wi-Fi, dedicated or managed Wi-Fi locations, observed time difference of arrival (OTDOA) based on Long Term Evolution (LTE), and metropolitan beacon system (MBS).

The FCC set up test beds for validating the approved methods for providing location, and vendors set up their own evaluations. Except in some urban cores, GPS is fairly accurate in reporting outdoor X and Y coordinates used to determine location. Some cellular operators use other types of location calculations including OTDOA, which works well as long as a minimum of three cell sites receive a cellphone’s signal. After the signal is received by the sites, it is triangulated, and the resultant location is also fairly accurate. Adding OTDOA to GPS results in an even more accurate outdoor location.

There are limitations to all the specified methods of calculating location. Providing the best possible location information both in the open and inside a building uses a blend of solutions from several vendors. For example, with OTDOA, if a caller is on an interstate where there are cell sites along the road, the odds of three sites being within range of the phone are much less than when the caller is in a suburban or urban area. Adding GPS to OTDOA results in more accurate location information being sent to the emergency communications center (ECC).

Other FCC-approved methods — for testing purposes, at least — include crowdsourced Wi-Fi. This is described in the NextNav white paper as follows: “Crowdsourced Wi-Fi, a solution used in commercial wireless services to provide ‘best efforts’ location, is expected to be a relatively inexpensive solution. Although its performance in urban areas is not yet fully known, it is well known that in poorer communities with high crime or elderly residents, where a large percentage of 9-1-1 calls are expected to originate, broadband/Wi-Fi penetration is so low that it is not expected to perform well, if at all, especially in cities such as Chicago and New York. Further, it will not work in times of natural disasters such as hurricanes and storms when the power goes out and 9-1-1 call volume is expected to surge. This system does not deliver accurate vertical information either. Despite the attractive initial cost factor and presence in some venues, crowdsourced Wi-Fi is not expected to consistently deliver required performance levels across the country and completely fails the ‘reliability’ and ‘continuity of service’ performance requirements across an entire metropolitan market. Therefore, it will likely be the more expensive long-term option both from a cost and a public relations perspective.”

The national database of Wi-Fi access points does not, by itself, meet FCC requirements. The NEAD is a national database of Wi-Fi access points and their corresponding street addresses that can return a dispatchable location for the caller. Due to the voluntary nature of the database, privacy and cybersecurity concerns, and lack of broadband penetration in poorer communities (only 50 percent of the population is served by Wi-Fi), only a small percentage of calls are expected to be supported using this solution. Regardless, due to the carrier commitment during the formulation of the rules, this solution will be built.

This brings us to MBS, the technology offered by NextNav. MBS is a complex technology that requires a series of beacon transmitters spread around urban areas and a receiver chip in every phone using the service. In tests I witnessed, Z-axis accuracy was much improved over the 3 meters required by the FCC. The issues are that in addition to beacon signals and the required receiver chip in every phone, it also depends on barometric pressure. Barometric pressure sensors are available in some phones today. However, the fire service is skeptical of using this type of Z-axis location because as the temperature rises in a burning building, the barometric pressure changes to a point of no longer being reliable.

NextNav and a few others understand that location accuracy in rural, suburban, metro and in-building situations will need to be achieved using different technologies for different locations. This is not about a single, one-size-fits-all solution; it is about sets of location technologies that can be stitched together for a better, more reliable outcome. The FCC seems to be giving the industry a list of technologies and saying, “Here, use one of these.” It would be more beneficial to say, “Here is a starting point, build on this and make it better over time.”

The FCC Ruling
I was, frankly, shocked by the FCC’s most recent Z-axis ruling. The FCC is requiring a height or Z-axis location that is only within 3 meters of the actual location. Three meters (10 feet) equates to a floor in most buildings. If the accuracy is within 3 meters and the caller is on the fifth floor, this location information could send responders to the fourth, fifth or sixth floor. Where buildings are built close together and there is a 10-foot variance, first responders could find themselves in the wrong building and on the wrong floor.

Even so, 3-meter accuracy is better than what we have today. With all the technology on the market and all the talented engineers, we should be able to solve this accuracy problem to a higher degree by knowing the Z-axis. While the FCC accepted what it was told is achievable today, its latest ruling requires the use of additional technologies to improve location accuracy over time.

At this juncture I have to ask why the Z-axis ruling is 3 meters with no incentive to tighten over time. There is, of course, a cost involved with location services. It costs money for cellular operators to set up their location systems and enable location reporting. I believe it is worth the cost to determine more accurate locations if it will help save lives of citizens and first responders. Network operators are in business to make money, but they are also in business to serve the public and the public-safety community, especially since the advent of the First Responder Network Authority (FirstNet).

I would like to see the FCC amend its ruling to require tighter Z-axis location criteria over time. While many rules have been met with “wow, we can’t do that,” or “wow that will cost more money,” when the auto industry faced miles-per-gallon standards, it not only figured out how to meet the new requirements, it beat them. I would expect nothing less from a wireless industry on the cutting-edge of technology. LTE, 5G and Wi-Fi 6 all can be used as ways to improve on the stated FCC requirements. When those in power believe we already provide the best possible location accuracy, there is little incentive for the industry to do better. However, we know we need to do better for public safety, and we will.

This story is part of a two-part point-counterpoint series about the FCC's 9-1-1 indoor location metric. Click here to read the other viewpoint.

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Andrew M. Seybold Sr. has been providing consulting services to the public-safety industry for more than 50 years. Seybold writes a weekly column known as The Public Safety Advocate, posted on allthingsfirstnet.com.

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