Pushing E911, locating VoIP

GPS World, May, 2006

Cell phone users will make an estimated 82 million wireless 911 calls this year. In many cases, emergency responders will not know how to reach them unless the callers are conscious, cogent, and capable of precisely communicating their location.

Wireless carriers and public safety answering points (PSAPs) have logged significant progress towards implementing wireless E911 since 2003, according to a March 2006 report from the General Accounting Office (GAO). Although the Federal Communication Commission's (FCC's) mandate for wireless phone locatability has laid the foundation for location-based services (LBS) and vastly increased GPS market potential in the United States, lagging capability has stalled widespread LBS deployment and restrained GPS/wireless market growth.

Deployment of wireless E911 usually takes two phases: Phase I provides general location information by identifying the cell tower or site receiving the wireless call. Phase II provides more precise caller-location information. Under Phase II, E911 callers on networks with handset-based solutions--assisted GPS (AGPS)--will be located down to 50-meter levels, while callers using network-based solutions such as time difference of arrival (TDOA) will only be located within 100 meters.

Nearly 80 percent of PSAPs (was 65 percent in 2003) of the more than 6,000 PSAPs nationwide have Phase I capability, and 57 percent (18 percent in 2003) have Phase II for at least one wireless carrier. The GAO says full implementation is several years away in many states, and may never be reached in five others.

Use of Funds. The GAO says that nearly all states require wireless carriers to collect surcharges from their subscribers to cover the costs associated with implementing wireless E911, with per-subscriber surcharges from $0.20 to $3.00 per month. States have the discretion to determine how they will manage and distribute the funds, and the GAO found the management of the funds and methods of disbursement varied widely. Although the GAO report does not so state, other observers have claimed that states' use of these funds for other purposes has slowed E911 implementation. The emergency response function has traditionally fallen under state or local jurisdiction. The FCC has no authority to set deadlines for PSAP readiness.

VoIP Calling. Now a new player has entered the emergency fray. Voice over Internet Protocol (VoIP) technology enables placing local and long-distance phone calls over the Internet, and is expected to account for more than 1 million 911 calls this year. Tabbed to grow rapidly in the next few years, VoIP's main attraction is low price. It also allows the consumer to take the phone from one location to another, plugging it in wherever Internet access is available--or accessing the Internet wirelessly. All calls to the VoIP phone route directly, regardless of its physical location.

"VoIP does not present anything new in the way of location challenges over wireless," stated Gregory L. Rohde, executive director of the E911 Institute. "And wireless will certainly move into an IP-based platform, so the location technologies will be the same. For examples of new technologies, TCS is working on a system that maps city locations by listening to Wi-Fi networks, and Rosum Technology has a similar solution using TV signals."

CARRIER CHOICES BY AIR INTERFACE

               TDMA      GSM       iDEN           CDMA

Handset-based                      AGPS           AGPS
                                   Sprint Nextel  Sprint Nextel
                                                  Verizon
Network-based  TDOA/AOA  TDOA/AOA
               Cingular  Cingular
                         T-Mobile
Hybrid         RFS                                AFLT
                                                  Sprint Nextel
                                                  Verizon

Some carriers have multiple interfaces across their networks.
AGPS: assisted GPS
TDOA/AOA: time difference of arrival/angle of arrival
RFS: radio frequency signature
AFLT: advanced forward link trilateration
Source: TechnoCom Corporation