Jon Harmer 2017-08-02 04:42:11
A hybrid location determination methodology improves the accuracy of location information for calls made to 911 and dramatically speeds the delivery of location information to call-takers at emergency operations centers. People make an estimated 240 million calls to the 911 universal emergency telephone number in the United States annually. The current 911 system for mobile phones was designed in 1996, before the devices were as smart or as ubiquitous as they are today. At the time, planners assumed that if you called 911 from indoors, you would use a landline phone. But today, an estimated 49 percent of U.S. households have no landline phone, up from 29.7 percent in 2011. And, 76 percent of all 911 calls in 2014 came from cell phones, up from 70 percent in 2013, according to the 2015 National 911 Progress Report. Today, when you call 911 from a mobile phone, several things happen. Most cell towers have three faces or sectors, each covering a 120-degree area extending from the tower. When a mobile device calls 911, one of the sectors of a nearby cell tower picks up the call. Equipment maps each sector mapped to a particular public safety answering point (PSAP) in a database and routes the call to the designated PSAP. When the call reaches the PSAP, the phone number of the caller and the location (address) of the cell site or sector appears on the call-taker’s screen. This is called the wireless (WRLS) or Phase I address. PSAP managers train the operators to know that this address is not accurate and to ask the caller for the location before asking what the emergency is. It can take a caller anywhere from a few seconds to more than a minute to say the location, according to statistics from California PSAPs. While the call-taker asks for the location, the PSAP computer-aided dispatch (CAD) system can rebid for a more accurate address, either automatically in the case of more advanced CAD systems, or manually by request of the operators. The rebid process then goes back to the cellular network to request a more accurate location, known as wireless Phase II (WPH2). General Approaches This process uses one of two general approaches. One uses radio-location information from the cellular network, such as angle of arrival (AOA) or uplink time difference of arrival (U-TDOA), and the other is to use a GPS receiver in the device itself. Additional hybrid solutions include assisted-GPS (A-GPS). This and other hybrid solutions are covered in detail in “FCC Amended Report to Congress on the Deployment of E-911 Phase II Services by Tier III Service Providers,” available at https://apps.fcc.gov/edocs_public/attachmatch/DOC-257964A1.pdf. It may take as long as 30 seconds for the Phase II address to appear on the call-taker’s screen, if it arrives at all. Frequently, PSAPs don’t receive this information or they receive it too late to be of any use. When they do receive it, it can be in the form of a dispatchable address (such as 123 Main St.), as a set of GPS coordinates, or both. The Phase II location information comes with an uncertainty factor that indicates how accurate it might be. It indicates a radius around the latitude and longitude within which the system determines a 90 percent chance the caller is located. There are several problems with the current state of affairs for 911 location information. The first is what is known as a Phase I misroute. This occurs when the cell sector covers more than one jurisdiction. Because, at present, the system has no way of knowing exactly where in a given cell sector the caller is, and each cell sector can map to only one PSAP, there are many areas of the country where 911 calls end up going to a jurisdiction that cannot dispatch help to their location because they are in an adjacent jurisdiction. Case Study: Shanell Anderson Call misrouting contributed to a delayed response when Shanell Anderson dialed 911 after driving her sport utility vehicle into a lake in Cherokee County, Georgia, and the call went through a tower in nearby Fulton County. “She repeated her location over and over, but it didn’t help,” an article in USA Today reported. “Because Anderson’s call was routed through the nearest cellphone tower to a neighboring county’s 911 system, the dispatcher couldn’t find the streets on her maps. Worse yet, the system couldn’t get a fix on the cellphone’s location before the call ended.” John Kelley and Brendan Keefe, who wrote the article, “911’s Deadly Flaw: Lack of Location Data,” reported that it took 20 minutes for rescuers to get to Anderson and pull her from her submerged car, barely alive. She died a week and a half later in the hospital. To help resolve the misrouting of as many as 5,000 911 calls annually, authorities in Benton and Franklin Counties in Washington state are taking steps to combine 911 dispatch centers at county and city levels. “Police and fire chiefs on both sides of the river agree that having dispatch centers so close but not combined leads to confusion, miscommunication and response delays,” wrote Wendy Culverwell in the Tri-City Herald story, “Pasco, Franklin County Ask to Join 911 Dispatch.” Calls from mobile phones are often routed to the wrong dispatch center. The misroutings cause unnecessary delays, often by as much as 10 minutes, Culverwell reported. The second issue with the current situation is the accuracy and timing of the Phase II address methods. Because the Phase II method determines the address after the call reaches the PSAP, the information cannot be used to affect the routing of the call, which is what contributes to the misrouting. Also, Phase II location methodologies often fail for callers who are indoors, where more and more callers are initiating wireless calls. Saving 10,000 People The FCC estimates that more than 10,000 people every year could be saved with a one-minute reduction in 911 response times, which average 11 minutes nationally, as Carl Bialik wrote in 2013 in his Wall Street Journal blog, “Giving No Time to Misleading Police Stats.” On Jan. 29, 2015, the FCC adopted a new set of indoor accuracy benchmarks requiring carriers to provide a caller’s location within 50 meters for 40 percent of all wireless 911 calls by 2017 and 80 percent of all wireless calls by 2021. The FCC set out the requirements in its Fourth Report and Order issued in PS Docket No. 07-114. The assumption at the time of the ruling was that the system was not capable of solving the problem on a shorter timeline. The Solution: Hybrid Methodology LaaSer Critical Communications of Atlanta has developed a patented device based on hybrid location determination methodology to address this problem. Instead of relying on the tower network to determine the location of the device, LaaSer’s system uses sensor information resident on today’s smart devices as well as network- based elements. This new devicebased system uses cloud computing technology both to enhance accuracy when determining location and to increase the speed at which the location is delivered to the existing infrastructure so that it can make its routing decision faster than is currently possible. LaaSer works within the existing infrastructure and addresses many of the issues present in the current location determination methodology. LaaSer calculates the user’s location based on the most accurate data available to that user’s mobile device, the same device originating the emergency services phone call. The multiple sensors on the caller’s device that LaaSer uses to determine a caller’s location include: ● Most recent location fix from operating system services ● GPS ● Wi-Fi ● Bluetooth low-energy beacons ● Near-field communication radio technology ● Accelerometer ● Barometer The LaaSer hybrid methodology collects this telemetry on the device as the user places the call to emergency services. At the moment the user hits send, the device sends the raw telemetry data to the location information server for processing. The location information server calculates the user’s location based on the most accurate information available to the mobile device. For example, if Bluetooth (or other) beacons that have a high accuracy are available, those are weighted more heavily than other methods. If Wi-Fi indoor positioning system (WIPoS) data is available and is deemed to be accurate based on the logic and algorithms contained in the location information server, then that information is used. If GPS data is available and is deemed to be accurate to within a predefined radius, then this information is used. Accuracy The location information server verifies the accuracy of the results determined using GPS, Wi-Fi and other telemetry data by cross-checking those results against the location of cell towers in range for the device. These cross-checks are configurable so that the location information server may fine-tune thresholds for accepting or rejecting telemetry data to produce the most accurate results possible when determining a user’s location. The location information server provides the determined location (X/Y/Z, uncertainty and civic address) to the existing mobile positioning center (MPC) to affect the routing of the call. This information is then sent in the form of X/Y/Z, uncertainty and civic address to the existing automatic location information (ALI) infrastructure so that the location information is available to the PSAP operator at the instant the call rings into the PSAP. Extensive testing has been performed following industry guidelines, across multiple states, in varying kinds of geography, and with an assortment of real-world scenarios simulated. The results of the tests show a marked improvement over the current system (see Figure 1). Research has shown that the value of accurate location decreases as time goes by on the call, largely because the 911 professional determines the caller’s location manually. Simply put, getting an accurate location earlier in the call dramatically improves outcomes. The testing shows that the LaaSer location information server provides a much faster and more accurate location regardless of the conditions of the call. Additionally, this more accurate (an average uncertainty of about 20 meters) location fix is achieved in time to be used to help determine the routing of the call to the correct PSAP (within 2 to 3 seconds of the call being placed) in the majority of cases. Compared with the existing system, the LaaSer hybrid methodology provides a much smaller uncertainty radius and the actual location is always within that uncertainty ring, which is not always the case with the current system (see Figure 2). Potentially most important, the LaaSer device and cloud-based system significantly reduces misrouting issues, so that no time is wasted by the caller talking to someone who cannot dispatch help to their location. Frequently, these misroutings result in much worse outcomes for the caller, so reducing them is of the utmost importance (see Figures 3 and 4). This entire solution has the potential to affect the current system in positive ways without having to replace significant portions of it, as the LaaSer hybrid methodology enhances and improves the current system by working within the existing infrastructure, instead of replacing it. Jon Harmer is chief marketing officer at LaaSer Critical Communications. Visit www.laaser911.com.
Published by AGL Media Group LLC. View All Articles.