Panel Examines E9-1-1 Phase II Location Accuracy, Delivery Issues
Monday, November 25, 2013 | Comments

Photo courtesy Find Me 911

A disconnect between wireless carriers and the public-safety community could be partially responsible for declines in the number of wireless 9-1-1 calls delivered to public-safety answering points (PSAPs) with Phase II location information.

The FCC hosted a discussion on E9-1-1 location accuracy Nov. 18 featuring representatives from wireless carriers, the public-safety community and location product vendors to discuss Phase II E9-1-1 location accuracy.

Much of the conversation centered on a report released in August by CalNENA, the California chapter of the National Emergency Number Association (NENA), that showed more than half of all wireless 9-1-1 calls in five geographic areas were delivered to PSAPs without location information. This represents a decline in the number of E9-1-1 calls delivered with Phase II location data from previous years.

California handles 19.7 million calls each year, 14.4 million of which originate from a wireless phone. In 2009, 60 percent of wireless calls were delivered with Phase II locations, but only 45 percent of calls came in with Phase II locations in 2012, said Karen Wong, assistant director of public-safety communications for the state of California.

San Francisco, which processes 1.2 million 9-1-1 calls annually, reported similar declines in delivery of Phase II locations. In 2008, 80 percent of calls were delivered with a Phase II location, compared with 20 percent this year, said Lisa Hoffman, deputy director for the San Francisco Department of Emergency Management.

Other states, including Utah and Texas, recently reported similar declines in accurate location data.

The FCC provides Phase II call tracking data here.


The Problem

Public-safety representatives participating in the FCC panel expressed frustration with the apparent backward slide in the delivery of location information with 9-1-1 calls.

Several factors were offered as potential reasons for this trend. The sheer volume of 9-1-1 calls originating from wireless devices is one potential cause.

The commission has monitored issues with E9-1-1 location during the past year. About 60 percent of 9-1-1 calls originated from wireless phones in 2011, and today some jurisdictions currently report that up to 75 percent of 9-1-1 calls come from wireless devices. A large percentage of those calls originate indoors, said Nicole McGinnis, deputy chief in the policy and licensing division of the FCC’s Public Safety and Homeland Security Bureau (PSHSB) during a Nov. 21 “State of 911” Webinar hosted by the National 911 Program.

More than 38 percent of households use wireless exclusively for their communications needs, and only 8 percent of U.S. households are wireline only, said Brian Fontes, CEO of NENA.

Another potential cause is the growing percentage of calls originating indoors or in urban canyons where location fixes are more difficult to obtain quickly. In addition, increasingly faster call setup times mean calls are often connecting to PSAPs before a Phase II location can be determined.

“When a call is received at the PSAP, the location is still being determined,” said John Snapp, vice president and senior technical officer at 9-1-1 system provider Intrado. “When a call comes into a PSAP, the system will typically do an initial bid to the carrier network for the location of the call and the callback number. What they receive back is Phase I information.”

As call setup times shorten, PSAPs will see Phase I information delivered more often, and the problem will only get worse as networks move toward faster IP and i3 networks, said Snapp.

Location technologies have inherent limitations, and delivering location information has always come with tradeoffs, said Ryan Jensen, director of technology and compliance for T-Mobile.

“Public safety has historically said that high accuracy is the top priority,” said Jensen. “They don’t want a bad location quickly. They want an accurate location even if it takes a little while.”


The Importance of Rebidding

The interval of time it takes for an accurate Phase II location to be delivered seems to be the cause of a disconnect between public safety, which is noticing the decline in location-information delivery, and the wireless industry, which says the information eventually is there but PSAPs must pull it.

Manual rebidding is just another step a dispatcher has to take during a sometimes stressful call, and many dispatchers prefer to spend time getting location information from their caller rather than rebidding for information from the network, Hoffman said.

Wireless industry representatives stressed the need for PSAPs to implement automatic rebidding procedures that would prompt the system to ask the network for updated location information at a predetermined interval so call-takers don’t have to do it.

Jeanna Green, network development engineer at Sprint, said nothing has changed about the technology or the delivery process to cause the declines in delivery of locations. Voice calls typically take between four and eight seconds to arrive at a PSAP, she said.

“Generally, this is not enough time for the satellites to calculate the position of a handset. A rebid must be done,” said Green.

A progression to assisted GPS (A-GPS) technology necessary to calculate Phase II locations has impacted delivery of location information, said T-Mobile’s Jensen.

 “There has always been the expectation that you would need to rebid to get a Phase II result,” said Jensen. “We had no choice but to implement A-GPS to meet requirements on a county level, and going along with that is increased latency. If all you are looking at is class of service at the end of a call, you are going to see degradation because you are not taking into account rebids.

“Introduction of automatic rebids is crucial,” said Jensen, who noted T-Mobile’s data shows that only 8 percent of 9-1-1 calls are rebid for location information. Sprint’s data shows PSAPs are rebidding only 15 – 35 percent of the time, said Green.

In some cases, miscommunication or lack of awareness is causing the rebidding numbers to be low. At one point Hoffman’s PSAPs were instructed to turn off auto rebidding because of technical issues. Word never got back to the PSAPs to resume auto-rebidding. She said it would be beneficial if wireless carrier representatives reached out to PSAPs when they notice trends like low rebid rates so issues can be resolved quickly.

Hoffman also noted that sometimes waiting for location accuracy information is not acceptable. A typical call in San Francisco lasts 90 seconds, and sometimes that is not enough to get location information, she said.

But Terry Hall, past president of the Association of Public-Safety Communications Officials (APCO) International said a late-arriving location is better than no location at all. Even if a location comes in at the end of a call, dispatchers have an additional opportunity to revalidate the location where they are sending responders, he said.


Tracking vs. 9-1-1

Many panelists referred to the public’s perception that dispatchers will always know exactly where they are when they make a 9-1-1 call. Panelists joked that the TV  show “CSI,” along with commercial applications that deliver coupons based on consumers’ specific locations, are creating misconceptions that their location is just as available to 9-1-1 dispatchers. But that isn’t the case, they said.

The reason commercial applications can readily find users is that consumers willingly give up their privacy and allow these applications to track them, said Susan Sherwood of Verizon. The network pings their phone every few minutes to ensure it always has a general idea of where that wireless phone is.

With 9-1-1 location, the industry wanted 9-1-1 callers to be able to be pinpointed without any prior knowledge of their location, she said. That cold start means that finding a location fix is going to inherently take longer.

“It starts another query as if it never knew where you were,” said Sherwood. “As long as a 9-1-1 call is live, we can rebid every 20 – 30 seconds, but we don’t track everyone just so we know where they are in case they call 9-1-1.”


Indoor Location

Another point of discussion was the importance of indoor location accuracy, especially in urban areas, following the FCC’s Communications, Security, Reliability and Interoperability Council (CSRIC) testbed. Current location accuracy rules only apply to outdoor location fixes, but the CSRIC testbed provides an independent means to validate vendor claims about indoor location technologies, which carriers say is crucial.

“We need a way to evaluate technologies independent of vendor claims of how technology works,” said Sherwood.

Representatives from NextNav, Qualcomm, TruePosition, TeleCommunication Systems (TCS), TRX Systems and Polaris participated in the panel discussion about indoor location accuracy.

Panelists noted the increasing use of small cells, microcells, femtocells and distributed antenna system (DAS) technology could eventually help with fixing indoor locations. Pre-planning and pre-mapping of new buildings with altitude information by floor could also help alleviate problems with locating callers in the vertical, or Z-plane.

Location technologies could allow for relative positioning, which would tell responders where they are in meters above the ground vs. where the caller is above the ground, allowing them to more easily find their target, said Ganesh Pattabiraman, founder and president of indoor positioning technology company NextNav.

Location accuracy is attracting attention throughout the public-safety community. Several law enforcement, public safety and emergency response organizations gathered for a press event outside the commission during the roundtable. The Find Me 911 coalition displayed a banner urging the commission to quickly establish location accuracy rules for wireless emergency calls.

The Congressional Fire Services Institute (CFSI) submitted a letter to the FCC supporting development of effective and accurate indoor location technology to assist with fire and emergency services response. Congressman Peter T. King, chairman of the House Homeland Security Subcommittee on Counterterrorism and Intelligence and co-chair of the Congressional Fire Services Caucus, submitted a letter to FCC Chairman Tom Wheeler, urging the commission to create rules requiring carriers to collect and share indoor location data with law enforcement.

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