Cellular Safety's 125-Meter Dash

By 2001, wireless companies must locate cellular 911 calls within 125 meters. The technology exists, but so do some formidable problems.

by / July 31, 1998 0
Last year in New Jersey, a 69-year-old woman from out of state was driving to see her friends late one night when her car's alternator broke. Without power to start the car or unlock the electric locks, the woman was trapped. Desperate, she called 911 on her cellular phone without a clue as to where she was located. In another New Jersey town, a 911 dispatcher received a wireless call reporting a car accident on Jacksonville Road, but the caller was unable to tell the dispatcher which of the four Jacksonville roads in the general area was the location of the accident.

In each of these incidents, help was dispatched quickly and to the right place, thanks to technology that can find -- within a few hundred feet -- the location of a wireless 911 call. The responses to these calls for help were just two of several thousand the New Jersey Office of Emergency Telecommunications Services (OETS) were able to identify and locate during a three-month trial of the country's first live wireless enhanced 911 service.

While the trial only covered a 50-mile stretch of the New Jersey Turnpike, it was the first time public safety officials attempted to identify and locate real wireless 911 calls. "We were able to reach and even exceed the FCC mandate," said Robert Miller, OETS executive director.

In 1996, the Federal Communications Commission issued requirements that wireless companies provide 911 dispatchers with information that identifies and locates 911 calls from cellular phones. The two-part phase-in of these requirements began in April this year and gives companies five years to upgrade their cellular networks with technology that tells 911 dispatchers the location of an emergency caller to within 125 meters.

However, if the FCC's goals are clear, how they are going to be reached is another matter. Decisions concerning technology, standards and cost must be hashed out. "How much all of this is going to cost is the issue," said Woody Glover, executive director of the 911 Network in East Texas. Trying to pinpoint the location of a cell call to within a couple hundred feet could become extremely expensive, said Glover and a number of experts.

While the FCC requires states to develop a cost-recovery mechanism, such as a user surcharge, to pay for the technology and upgrades, it's not entirely clear what the money will pay for -- the infrastructure necessary for locating wireless calls or just the equipment for handling 911 emergencies. One person who is not surprised by the intricacies of wireless 911 is Bill Munn, president of the National Emergency Number Association (NENA) and executive director of the Tarrant County, Texas, 911 District. "This whole issue has become a lot more complicated than people thought," he observed.

Explosive Use

It comes as no surprise that the explosion in cellular phones has led to spectacular growth in 911 calls from people on the go. Figures show that 50,000 emergency calls per day -- as much as 25 percent of all 911 calls -- are placed from cell phones. Unfortunately, wireless calls cannot be identified and located the same way as landline 911 calls. As a result, a 911 cell-phone call may be misrouted by hundreds of miles. By the time dispatchers are able to home in on the actual location of the call, precious time may have been lost. Ironically, most people cite personal safety as one of the reasons for using cell phones. Very few consumers are aware of the fact that wireless calls are hard to locate.

When someone dials 911 from a landline phone, the call and the caller's phone number are passed by the carrier to a 911 switch, which uses the phone number to look up the name and address of the caller in a database known as the Master Street Address Guide. The name and address are then used to determine the closest public safety answering point (PSAP) to the caller. The guide also determines which fire, police or medical service is closest to the caller. All this information appears on a PSAP dispatcher's computer screen, allowing the dispatcher to promptly send service to the caller's location.

However, when a caller uses a wireless phone to dial 911, the dispatcher sees a blank screen. Without any information, the dispatcher has to determine the caller's identity and location from the caller, which is not always possible in every emergency. "If we have one accident on our freeway," said Munn, "we'll get as many as 50 wireless emergency calls and many of the callers provide erroneous location information."

As the number of wireless 911 calls has increased in recent years, wireless carriers and public safety groups, such as NENA and the Association of Public Safety Communication Officials (APCO), began pressuring the FCC to establish regulations enabling 911 services to properly handle wireless emergency calls. In 1996, the FCC set two deadlines for identifying and locating wireless 911 calls:

* By April 1, 1998, each wireless carrier must give PSAPs a 10-digit callback number and location data of the specific cell site or cell sector where the call originated.

* By Oct. 1, 2001, wireless carriers must provide more precise location information for each 911 call.

Jack Keating, president-elect of APCO and executive director of West Covina Communications in Southern California, believes these deadlines are overly optimistic. "You have to remember that the service doesn't just happen. The PSAPs have to ask the wireless carriers to provide the 911 service to them, the PSAPs have to have the means of receiving the information from the carriers, and they have to have some sort of cost-recovery system in place."

Most public safety officials agree that the first phase of the FCC mandate will be the least costly to implement but hardest in terms of setting standards for technology. Take, for example, standards for viewing information on wireless calls. According to Glover, who heads APCO's committee on wireless standards, most call centers and their dispatchers want the new information for wireless calls to come in on their existing equipment, but one leading solution calls for installing separate phone lines and screens for emergency cell calls.

The second phase presents an even more challenging issue: which technology to use for locating wireless callers to within a few hundred feet of the call. Dispatchers can't depend on textual information as they presently do for landline calls. Those calls come in with a street address, which the dispatcher reads out to the police, fire or medical crews. Location information for wireless calls will come in some form of a latitude and longitude coordinate; since dispatchers can't use that information, their workstations will have to be upgraded to handle electronic mapping.

Wireless carriers are quick to point out that the text vs. graphics display of location information is a Phase II issue only. For Phase I, carriers are telling PSAPs that they will be able to provide basic cell-site information in a text format that will not force a costly equipment upgrade.

However, carriers realize that they will have to settle on one technology for pinpointing the location of a caller, if PSAPs around the country are going to use the service. Right now, there are two competing technologies.

One uses a technique called Time Difference of Arrival (TDOA), which calculates a telephone's location, speed and direction of travel. TDOA works on the physics of radio waves. When a cellular phone makes a transmission, the radio waves travel like water ripples when a pebble is tossed into a pond. Special receivers installed at each cell site pick up the radio wave signals and time-stamp them. Once the signal has been time-stamped by
several receivers, the time differences are calculated and the result is used to triangulate an intersection point at or near the true location of the phone.

In New Jersey's test of location technology, the state used a system from TruePosition of Bala Cynwyd, Pa. [see "Put a Location in Wireless E-911," Government Technology, October 1997]. Test results showed that TDOA can locate about 67 percent of the wireless calls to within 410 feet, which meets the FCC's 125-meter requirement. Results also showed that a greater saturation of receivers on cell-tower sites improved the accuracy of the location information coming into the dispatchers.

Privacy advocates are concerned about a technology that can locate any wireless caller at any time. They would prefer to see carriers adopt a second alternative. This one calls for putting a global positioning system (GPS) receiver in the handset of cell phones. With GPS receivers, carriers wouldn't have to deploy costly receivers on every cell site. More importantly, callers would be able to control when his or her position would be given out.

A GPS solution would also display the coordinates of the phone's location to the person carrying it. A wireless-phone user could call a gas station after running out of gas and tell the tow truck driver where to find the car by reading its position off the phone's screen.

TDOA advocates point out, however, that GPS would not work in the millions of cell phones currently in use, rendering a large segment of the population invisible to location technology. FCC regulations require carriers to locate two-thirds of all cellular calls.

Business Opportunities

In 1997, 10 states passed wireless E-911 bills dealing with cost recovery and indemnification of carriers. This year, legislation is expected to be introduced in 21 states. On average, most legislation will tax wireless customers 75 cents per month for the service.

While all the legislative activity indicates a growing awareness for the need to fund wireless E-911 service, debate is growing over who should pay and for exactly what. While public safety is driving the need for location technology to find cell-phone users, wireless carriers can expect to profit from other business uses for the technology.

For example, wireless carriers can use the technology to locate and detect possible fraud from cell-phone number cloning. Cloning involves stealing phone numbers from legitimate cell-phone customers and then using the numbers to make fraudulent calls. With location technology, carriers could quickly track down perpetrators of this fraud. Another application is billing by location. Wireless carriers could offer to bill customers according to where they use their phone, along with usage rates and time-of-day rates. Carriers could bill one rate for calls made on the road and another for calls made from home. Other possible applications involve fleet management and inventory monitoring.

Since location systems are as much a business opportunity as a public service, most PSAPs believe cost recovery should pay for the necessary modifications to their equipment and dedicated trunks for handling wireless 911 calls. PSAPs believe carriers should recover their own cost for the location systems. However, some carriers are arguing that states should pay for all initial costs and customers should then cover ongoing operational costs.

According to Keating, APCO believes that public funds should not pay for technology that will be used for business purposes. Others concur. In a newsletter published by NENA, OETS' Miller cautioned carriers from assuming that the FCC's requirements are tantamount to a federal mandate and, therefore, public funds should pay for the location technology. "If the public sector were to pay for the location systems," wrote Miller, "they would reserve the right to approve the system design, including the placement of all components, and the system could not be used to generate revenue for commercial carriers."

Instead, Miller argued, let carrier competition build the best location technology. The results will be a system in place much sooner than one built under the direction of the public sector. The FCC rule states the performance requirements for locating wireless 911 calls, explained Miller, "It doesn't tell carriers how to get there."



August Table of Contents