The biggest challenge cellular mobile phones introduce for 911 is location accuracy—especially during an emergency call. The problem is a global one, inherited with any wireless technology. Getting the location wrong directly impacts the level of safety provided to citizens, as routing the call to the most appropriate Public Safety Answer Position (PSAP) specifically relies on this critical piece of data.
Can you find me now?
Many of us don't stop and think how our mobile devices determine where we are on the planet, and most of us will assume GPS plays a significant role in providing that answer. While GPS remains an important piece of the location puzzle, quite often it is not the answer by itself. Fundamentally, there are three sources for location information used by cellular phones.
First, there is the tower identifier where the device is connected to the public switched telephone network. This information by itself may provide some insight, but it provides little granularity to actual device location within a reasonable area.
Second, slightly more accurate but still having many caveats, is the signal coming from GPS satellites. While these can be precise when devices are outside "in the clear," many times tall buildings that form urban canyons can play havoc with these radio signals, causing them to be inaccurate.
The third, and likely the most accurate location method, uses Wi-Fi fingerprinting. The sheer number of Wi-Fi access points, both public and private, and the fact that each device has a unique base service set identifier (BSS ID), prove they are excellent beacons when logged into a database with location. With enough data points in the database, no matter where you are on the planet, the visible BSS IDs and measured signal strength can be used to calculate where you are.
想到这way: You are inside your favorite mall. You look around and see Sunglass Hut, McDonald's and Banana Republic. Any database that contained the location of each of those stores could then tell you where you were inside the mall, including the exact floor information, critical in a multi-story building. But who has all of this data for the entire planet?
Google, Apple and the Skyhook database
For years, by your clicking "agree" on the End User License Agreement (EULA), applications have been granted access to your location information and have been given the right to share that information. In the background, these apps have been quietly contributing to ginormous location databases managed by Google, Apple and Skyhook.
In a recent conversation with the folks at Skyhook, they said the contributions to their database alone now exceed 2 billion entries. Even more impressive is the fact that this enormous cache of BSS IDs and locations has become somewhat autonomous. As devices report themselves to the database, any new visible BSS IDs are added. As more and more devices see these IDs, the proprietary mathematical calculations gradually zero in on their location. The more reports, the more accurate the database becomes.
The EU solution for emergency services
According to U.K. public safety specialistAdrian Brookes, “BT (British Telecom) handled as many as 40,000 incidents a year where they were unable to establish a location for the caller, consequently forcing emergency services to search for the event.”
While BT knew how to extract location information from mobile phones, doing so would require support from both the handset manufacturers and the operating systems in the devices.
According to Brookes, “Under existing location determination methods being used, not only was the location information incredibly inaccurate, [but] in some member states across the EU, the location was being delivered 10 minutes after the fact—and in a few cases, such as Greece, by FAX.”
With the support of theEuropean Emergency Number Association(EENA), BT reached out to EE—a European mobile network operator (MNO) that includes carriers Orange UK and T-Mobile UK—and equipment manufacturer HTC with a request to see if this new architecture could be developed.
“Both EE and HTC accepted the challenge, and within a very short period they were able to show a [proof of concept] that delivered highly accurate location information provided by way of SMS" that was both invisible to the handset owner and free, Brookes said.
What level of accuracy did this achieve? Since the new service can determine if GPS (GNSS) or W-iFi fingerprinting is more accurate at the time of the request, the best possible data is used. During testing, the reported level of accuracy obtained was touted to be 4,000 times more accurate than the current system. The new service has been given the nameAdvanced Mobile Location(AML).
For AML to be successful, the ultimate cost would certainly be an issue. Fortunately, no significant capital investment was needed by the carrier, the handset manufacturer or the emergency services agencies—or even the citizens who used it.
Getting AML implemented
How does this new technology get implemented? Quite simply, producers will need to add functionality to their code platform. When a user makes an emergency call, the geodetic (GPS/GNSS) and Wi-Fi information must be collected and then passed to public safety officials so that they can use the data in their existing systems. Getting the data to them can be via SMS, text message or even an HTTP post.
While nothing has officially been announced by the obvious candidates, it's not a hard stretch to imagine this construct is being worked on.
What about the 911 app?
We are taught to dial 911 for emergency services, not fire off an app. For this reason, using an app to collect and send this critical data set along to public safety is a bit of a stretch. But with AML solving the problem of getting data to emergency responders, the operating system providers need to provide just an API that triggers that communication link when a user makes a call. As for my crystal ball, I see that right around the corner, as this problem is now widely known and large companies that typically show good corporate responsibility will act quickly.
Microsoft, Google and Apple, the ball is clearly in your court. You can show the world that public safety is important to you and your customers. As for the FCC, as well as Canada’s CRTC, those agencies need to monitor these developments closely and account for inclusion in their future legislative agendas. Lives depend on it.