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Enhanced 911 (E911) Position Location Info

In 1996, the FCC issued a Report and Order requiring all wireless carriers and cell phone manufacturers to provide the capability for automatically identifying to emergency dispatchers the location from which a wireless call is being made. Timing for implementing the E911 requirements is divided into two phases. Phase I requires wireless carriers to deliver to the emergency dispatcher the telephone number of a wireless handset originating a 911 call, as well as the location of the cell site or base station receiving the 911 call, which provides a rough indication of the caller's location. This phase was implemented by the end of 1998.

Phase II requires carriers to deliver more specific latitude and longitude location information, known as Automatic Location Identification (ALI), to the dispatcher. There are a number of interim milestones for full implementation of this phase, beginning in March 2001 and ending with complete implementation by the end of 2005.

FCC's 1996 rules reflected existing technology at that time. The original rules would only permit network-based solutions. More recent advances in position location technology made it possible to meet the intent of E911 by using handset-based techniques. In September 1999, the Commission adopted a Third Report and Order, which set forth deployment schedules for wireless carriers using either handset- or network-based technology to satisfy the Phase II requirements. This was followed by a Fourth Memorandum Opinion and Order, which addressed several concerns raised in this document.

Under the current implementation plan, The FCC established a four-year rollout schedule for Phase II, beginning October 1, 2001 and to be completed by December 31, 2005. FCC has granted a series of waivers to specific interim requirements that establish individual schedules and required reports for many of the individual service providers. These are outlined in the FCC page listed below under Other E-911 Resources.

Providing the E911 service in a manner that is economically feasible for the carriers has proven to be quite a challenge! The headaches aren't over yet -- for example, many of the location technologies use GPS. This causes lots of concern over the use of UWB (ultra wideband), and possible concerns with interference between UWB devices and GPS. You can read about this issue in depth, and find out more about GPS in our UWB and GPS pages listed under Related Information on SSS Online below.

Take some time to explore the articles, resources, references and links below to learn more about this rapidly evolving subject!

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Related Information on SSS Online

Wireless Glossary

Ultra-Wideband News

GPS Info Page

CDMA Stuff Page

W-CDMA Stuff Page

Third Generation Wireless Info Page

PCS/PCN Info Page

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News Articles on E911

APCO tells President Bush to force VoIP to access 911 — By Heather Forsgren Weaver Feb 16, 2005, RCR Wireless News.
Enhanced 911 calls still far from wide coverage — October 2002 article by Paul Davidson, USA TODAY. Good information on status and problems at that time.
Are police ready for wireless 911 calls? — July 2001 article from C/Net News.Com
E911 - Mandate or Opportunity? — article by Tim Kridel, Wireless Review, November 15, 1998
Interesting information on Cellular Geolocation in this IEEE Forum discussion

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Articles from SSS Online's Technical Briefings Archive

ADOBE Acrobat (.pdf) Files Relating to E911:
e911.pdf Various Authors, Paper -- "Providing Universal Location Services Using a Wireless E911 Location Network" -- (~135K) -- (Thanks IEEE!).	radioloc.pdf Caffery and Stuber's April 1998 Paper (Georga Institute of Technology) -- "Overview of Radiolocation in CDMA Cellular Systems" -- (~88K) -- (Thanks IEEE!).
1cellular.pdf Prof. Randy H. Katz' (UCB) Briefing -- "CS294-7: Cellular Telephony" -- (~489K).	1dsss_intro.pdf Phil Flikkema's (USF) Briefing -- "Introduction to Spread Spectrum" -- (~110K).

Read ICUCOM's ACOLADE IS-95 CDMA Library Description
(with a Great intro to IS-95 in the first few pages).

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OTHER E911 Resources:

FCC's E911 Home Page. This page has press releases, text of the FCC documents, implementation reports from wireless carriers, presentations, and more.
Wireless 911 Information. An excellent, up-to-the minute presentation of the current status of implementation of E911, putting it all in perspective and providing lots of interesting links. This one is a must see!
Wireless Development Network E911 News and Resources page — lots of articles and tutorial info here, too.
CTIA's E911 Page
Web-o-pedia: What is E911 - This page describes the term E911 and lists other pages on the Web where you can find additional information
Disabilities Issues Task Force E911-TTY Compatibility Home Page
National Emergency Number Association
QUALCOMM -- "The Home of CDMA"
Wireless Developer's Network E911 page
MicroDATA GIS - a company that specializes in E911 wireless software
Locate Networks -- this company integrates ReFLEX wireless networks with advanced GPS to enable the signal to reach small, portable devices, even indoors and in urban canyons, where ordinary GPS does not operate. A location request is initiated through a Web site and forwarded onto the wireless network. The device captures and calculates GPS data and sends it to Locate Networks servers via the wireless network. Their Wide Area Reference Network (WARN) data enhances the accuracy of the GPS information. The data is then calculated, translated into a street address range, and mapped.
TruePosition, Inc. -- their products use TDOA location identification technology. They advertise that their U-TDOA technology works with all existing and future wireless phones without modification and accurately locates calls made in all environments, including dense urban and indoor areas.
U.S. Wireless -- Their propietary location pattern-matching technology known as RadioCamera did not require line-of-sight triangulation involving multiple cell sites. The system was one of the first to pass FCC E911 testing in April 2001, but the company went bankrupt in August of that year and all its assets, including the RadioCamera technology, were purchased in December 2001 by TrafficMaster. The TrafficMaster website lists products for vehicle navigation, traffic congestion information, and vehicle tracking. There is no mention of RadioCamera.
Teletrac, Inc. -- Another vendor using proprietary TDOA for location-identification, primarily for vehicle tracking systems. The advertise that their products are also compatible with GPS and CDPD systems. Their principal product is called Fleet Director, and is aimed at commercial fleet management. This company went bankrupt in 2001 and is now a wholly owned subsidiary of TrafficMaster.
Cell-Loc, Inc. -- Another vendor using TDOA for location - see their explanation of this technology written for the layman.
LoJack Corp. -- The stolen car locator company is looking at using their AOA system for E911 applications.
Wireless Link Corp. -- GPS-based vehicle location identification products.
TeleCommunication Systems -- another position location player.
Geometrix -- The E-911 solution from Allen Telecom's Grayson Wireless Division.
Deidra Ritcherson's (UCB) Briefing "The Effects of Forward Error Correction Coding and Hybrid-ARQ on Throughput and Delay in CDMA and W-CDMA Systems"
Wireless Systems Design Article on E911 Technology, "Position-Location - Whose Technology?" March 2000. This article includes lots of information on the various manufacturers involved in developing E911 systems, and an analysis of the revised FCC Phase II requirements.

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