About 80% of the 240 million phone calls received by 911 public safety answering points (PSAPs) come from wireless callers. The goal of regulators is that technology automatically identify the location of callers even if callers don’t know where they are or are unable to speak the information because of injury or constraint by an attacker. The idea is to convey a “dispatchable location,” enabling first responders to figure out “which door to kick in” when they arrive on the scene of an emergency. The Federal Communications Commission (“FCC”) has now adopted rules to help locate callers in terms of not only the street address but also the vertical location within a multi-story building.
The FCC has rules in place for automatic transmission of the street address where a call originates; but in the case of a multi-story building, street address is not enough to locate the caller. You also need to know on which floor to look for the caller. The height is called the “z-axis,” based on the traditional “x-y-z-axis” labelling of a three-dimensional graph.
Technology for determining z-axis information has improved, and the FCC has now adopted rules mandating an accuracy of plus or minus 3 meters in reporting vertical location. That is not enough accuracy to be sure of pinpointing the exact floor on which a caller is located, and some have argued that being one floor too high or too low is simply not good enough for first responders. Others have argued that we have to start somewhere, and we should start with a level of accuracy that has a good chance of being achievable in practice.
Think a minute about the complexity of determining height above ground. Should the determination be handset-based or network-based? It is mostly handset-based today, because a network-based system would require sensing equipment of some kind installed on almost every floor of every building. A handset most often determines height with a built-in barometer. But what if the building has a mezzanine, and the “first floor” is one or two floors above ground? What if 13 is skipped in numbering the floors of a building, which is true in some buildings but not others?
The tentative solution is to report “height above ellipsoid” (HAE). Maybe you know what that is, but maybe your mathematical knowledge isn’t so good. HAE is close to, but not exactly the same as, height above ground or above sea level. An ellipsoid is a mathematical model of the shape of the earth. HAE information has the strong virtue of being determinable by today’s devices – it’s the result you get from a GPS receiver, for example. However, raw HAE information is not going to pinpoint an exact vertical location of without refining it with information about the specific building, such as the height of each story (are the ceilings high or low?) and the way floors are named or numbered (the top floor of the FCC’s building, which has 11 floors, is still called the “8th Floor” for nostalgic reasons, because Commissioners’ offices were on the “8th Floor” of their previous two office buildings). In other words, to make the information really useful, you need a database that tells you something about the design of every multi-story building in town. Some cities have that, but a lot of places don’t. The FCC has left it to the PSAPs to figure out how to use raw HAE; the phone carriers only have to report the information. Among the things PSAPs can do is to compile databases of buildings, not an inexpensive proposition; but there may also be devices that can be carried by first responders that, upon arrival at the scene of an emergency, will mimic the data reported by the caller and thus enable responders to go up into the building until their devices match what the caller is reporting.
So the deal is that existing rules which have required wireless carriers to meet phased-in horizontal location accuracy requirements since 2012 will be expanded to require z-axis information for 80% of wireless calls by April of 2021 in the top 25 markets and 2023 in the next 25 markets. The z-axis requirement will apply to all handsets that can support the requirement without a hardware upgrade and will not be limited to devices with barometers or to new devices. It seems that most handsets in use today will work with a software upgrade, which will have to be provided, and the cost of which the FCC finds to be nominal.
Just to make sure that the data miners of the world don’t find a new way to make a bundle off of this information, the FCC’s rules will forbid the use of E911 call data for any purpose except public safety.
The new z-axis requirements are subject to approval by the Office of Management and Budget (OMB), a process which takes an uncertain amount of time but should be completed well before the 2021 initial compliance deadline. Further comments are invited (deadline not set yet) on when and to what extent the 3-meter accuracy requirement can be tightened. The FCC also wants to hear what people think about how location determination will work during electric power failures if it becomes dependent on externally powered mini-cell sites and Wi-Fi access points. If you can find a caller in a burning building only if the power stays on, the effectiveness of the system might be considered by some people to be a bit impaired.
The FCC’s new rules are an attempt to address the conflicting views among those who say that technology is still evolving, and it doesn’t work all that well yet; public safety officials who strongly desire more help right now in locating callers in distress; and people who ask who will pay the cost of creating new databases and developing techniques for translating raw HAE information into usable information to pin down which door to kick in at the scene of a crisis.
Petitions for reconsideration are likely. Hopefully, progress will be made in developing and implementing achievable rules, and lives will be saved.