The Evolution of Emergency Calling: Next-Generation 911 and High-Accuracy Location
Oct 31, 2012
The first 911 call in the United States was made in 1968 in Haleyville, Ala., on an old-fashioned rotary-dial telephone similar to that in Figure 1. Since then, massive advances in the way people communicate have forced the once-pioneering 911 system to evolve. These changes can be categorized as follows:
- Technological. A major change over the past two decades has been the penetration of wireless technology so much that mobile phones now are ubiquitous. The other major technological change is the availability of high-accuracy location technologies to assist in locating mobile emergency callers.
- Societal. Perhaps the most impactful changes are the ways in which people communicate, the devices they use and the environments in which they use these devices.
- Regulatory. Mandates and other regulations enforced by the Federal Communications Commission (FCC) impacted telecommunications providers, technology vendors and, ultimately, end users.
These three factors have combined to create 911 scenarios that the first emergency callers in Alabama in 1968 could hardly imagine.
Technological: All Location Methods Not Equal
The mobile geo-location industry emerged in the late 1990s, following the first FCC E911 mandate. A variety of low-, medium- and high-accuracy performance location technologies emerged as a result of the mandate. However, only the high-accuracy solutions were deployed by operators for meeting the FCC mandate. Location-accuracy performance and reliability requirements vary by the type of application they serve, driving the selection of the appropriate location solution from the following:
- GPS solutions have several benefits and limitations. GPS-based location methods require GPS receiver chipsets to be included in the caller's mobile device. Although the number of GPS-enabled devices is increasing due to widespread adoption of smartphones, the technology isn't ubiquitous from a global perspective. And even if a phone is GPS-capable, many users shut off the GPS feature to avoid battery drain.
- GPS solutions take relatively longer to locate a target, resulting in possible life-threatening situations for emergency callers. GPS solutions work well in direct line-of-sight conditions with the satellites (open-sky conditions), such as suburban and rural areas, but are challenged in dense urban (urban canyons) and especially indoor environments where most calls originate from.
- A standards-based alternative location method is RF Pattern Matching (RFPM). This network-based positioning method is based on radio-link measurements collected from the network and/or device, and it relies on predictions or models of the radio environment against which it performs an algorithmic comparison of the measurements to determine a best-match estimation of the device location.
In short, it uses the device's own radio signals to identify its location, eliminating any dependency on satellites or other network hardware. RFPM can locate all callers across any air interface and in any environment, eliminating limitations related to phone type or network technology. RFPM works well in non-line-of-sight conditions such as dense urban and indoor environments, complementing GPS, and is highly reliable for mission-critical public-safety applications.
Societal: Changing Habits
The explosion of smartphones led to changing habits among U.S. mobile users. Beyond being a simple voice instrument, phones now are used for text messaging, taking and distributing photos, recording videos, etc.
E911 infrastructure and Public Safety Answering Points (PSAPs) have struggled to keep up with these changes, when not ignoring them altogether. Nowhere was this better illustrated than during the 2007 Virginia Tech mass shootings, where students hiding from the gunman were unable to silently text 911 call takers and thus avoid giving away their whereabouts by talking on their phones.
Stemming from that, the FCC will require that callers have the ability to text to PSAPs. In addition, there's also great interest within the public-safety community to be able to receive actionable information on emergency situations (e.g., images from fires, etc.) as part of the 911 call process.
High-accuracy location, already part of the public-safety infrastructure, could be better integrated to provide detailed intelligence for first responders and emergency callers. For example, when texting 911, similar emergency calls in a given radius could be identified to alert authorities to larger emergencies, such as a terrorist attack or natural disaster.
Transmitting a geo-tagged photo could help emergency responders locate someone in a crowded sports stadium or shopping mall. And indoor location, which RFPM uniquely enables in a software-only solution, is vital in the example of a school shooting, where students are huddled under desks or in closets, away from GPS signals.
Societal: Reliance on Mobile Devices Indoors
Sources ranging from the Environmental Protection Agency to Centers for Disease Control and Prevention to J.D. Power cite a drumbeat of statistics to illustrate the fact that society depends on mobile devices to operate in all environments:
- More than 25 percent of U.S. households use only a mobile device for daily communications, and 15 percent of U.S. households retain a wireline phone but primarily rely on a mobile device for daily communications.
- Americans spend an average of 80 percent of their time indoors, whether at home, work or in a shopping mall, theater, restaurant, etc.
- As a result, approximately 60 percent of all calls on wireless networks originate indoors.
The logical outcome of all this indoor calling from mobile devices is that the percentage of 911 calls placed from mobile devices indoors is increasing. Although PSAPs don't track this statistic, the FCC states that 70 percent of all 911 calls are made from a mobile device, so a significant amount of those calls are assumed to originate from mobile devices indoors.
In addition, there's a difference between an "indoor" location in sight of a window and better able to receive external signals vs. "deep indoors" (e.g., in the center of an office building or shopping mall), where external signals are unlikely to penetrate. In the case of "deep indoors," alternate technologies may be required.
Regulatory: Evolution of the U.S. Location Mandate
With widespread adoption of mobile phones and the need to accurately locate callers not tethered to a fixed address, the FCC first adopted an Enhanced 911 (E911) location mandate (Phase I) in 1995 (see Figure 3). This stipulated that wireless network operators must identify the phone number and cell-phone tower used by emergency callers, following a request by a PSAP.
E911 is paid for by the imposition of a monthly surcharge on subscriber mobile phone bills. At the time, wireless operators used various location methods to comply with the mandate. However, as the accuracy of location technologies improved, emergency responders and consumer-advocacy groups called for FCC to strengthen its mandate to reflect improved accuracy capabilities.
The Phase II updated mandate, issued in September 2010, outlines a gradual strengthening of accuracy thresholds and compliance areas across handset-based technologies, such as GPS, and network-based technologies, such as RFPM and U-TDOA, where the location capability is driven by software or hardware respectively in the wireless operator's network.
This new mandate has been embraced by the U.S. public-safety community and wireless industry as the best way to ensure a robust public-safety infrastructure. In the next five years, FCC guidelines will again evolve by expanding the methods available to emergency callers to dial 911, including text, e-mail and video.
Technological: Pinpointing Location with High Accuracy
The United States provides a test case to disprove objections that high-accuracy location solutions require expensive up-front investment that doesn't justify the commensurate increase in accuracy. Besides the obvious response that it's impossible to put a price tag on technology that saves human lives, Figure 4 illustrates that an investment in high accuracy can produce cost savings for public-safety agencies.
Consider two location solutions: Solution A is accurate to within 50 meters, and Solution B is accurate to within 150 meters. To locate the same emergency caller, authorities using Solution B need to cover an area nine times larger than those using Solution A. The Solution B authorities need to deploy nine times the number of resources or take nine times as long to locate the emergency caller. Both outcomes result in increased expense, and taking longer to locate an emergency caller could mean the difference between life and death.
Current State of 911
Although technological, societal and regulatory changes will continue to occur, the U.S. 911 system is in a state of digesting recent changes and implementing solutions. The current updated FCC mandate is less than two years old, and, although its regulations impose significant change on local PSAPs, these changes are designed to phase in over a period of years, with ample extensions and exclusions.
Technology is always evolving, but the market has spoken, and GPS, RFPM or, more likely, a hybrid combination of the two is positioned to dominate 911 location-technology choices going forward. Societal changes may occur more slowly than other types, but when they take place, they often spread rapidly, such as the use of social media. They're also often generational, with young people typically more likely to adopt new ways of communicating.
Whatever happens, emergency callers can be assured that their calls will be answered and help will be dispatched quickly to them, just like the callers on that old rotary phone in Alabama four decades ago.