E9-1-1 Technology Background and Issues

Prepared for the Wireless E9-1-1 Technology Roundtable
September 26, 2002
San Jose, CA

1. Background

"When someone calls 9-1-1 they expect to get help right away. We cannot, and will not, accept a system where these callers cannot be located as quickly as possible."
     - Norman Y. Mineta, Secretary of Transportation, April 8, 2002.

America is increasingly dependent on wireless phones for reporting traffic crashes and other emergencies. However, location identification service for wireless telephone users is not yet available across most of the United States. Wireless Enhanced 9-1-1 (or WE9-1-1) implementation is needed to automatically locate these calls, thereby helping to save lives and improve emergency services.

Many factors complicate the efforts to deploy wireless 9-1-1 services throughout the country. These generally fall into technical, economic, logistical, and institutional categories. All are significant and substantial. The focus of this white paper, and the corresponding Wireless E9-1-1 Technology Roundtable sponsored by the U.S. Department of Transportation (DOT), is on potential technology solutions to 9-1-1 challenges and the implications of emerging technologies and services on the future delivery of emergency response.

1.1 Overview

In the late 1960's the three-digit number "9-1-1" was introduced as the telephone code for citizens to request emergency assistance. During the next two decades, deployment expanded rapidly — today wireline 9-1-1 service is available to about 98 percent of the U.S. population.¹ In 1999, Congress designated 9-1-1 as the universal number for emergency calling in the United States.²

The code 9-1-1 was chosen because it best fit the needs of all parties involved. It meets public requirements because it is brief, easily remembered, and can be dialed quickly. Since 9-1-1 is a unique number, never having been authorized as an office code, area code, or service code, it best meets the long range numbering plans and switching configurations of the telephone industry.³

There are three core operational characteristics of most wireline 9-1-1 services that enable Public Safety Answering Points (PSAPs) to most efficiently and effectively coordinate emergency responses:

• Selectively route the call to the nearest PSAP;
• Identify the caller's telephone number to enable call back and other services; and
• Determine the address of the telephone to speed the emergency response, especially in circumstances where the caller cannot talk or does not know his location.

To facilitate such enhanced 9-1-1 (or E9-1-1) service for wireline phones, the local wireline carrier determines the caller's location through software and databases which identify and associate a caller's phone number with the corresponding customer address. However, the technical solutions used for wireline E9-1-1 are not applicable to wireless emergency calls. New technologies and procedures are necessary.

In a series of orders since 1996, the Federal Communications Commission (FCC) has taken action to improve the quality and reliability of 9-1-1 emergency services for wireless phone users by adopting rules to govern the availability of basic
9-1-1 services and the implementation of E9-1-1 for wireless services.⁴ The wireless E9-1-1 program is divided into two parts - Phase I and Phase II. Phase I requires carriers, upon appropriate request by a local PSAP, to report the telephone number of a wireless 9-1-1 caller and the location of the antenna that received the call. Phase II requires wireless carriers to provide far more precise location information, within 50 to 100 meters in most cases. The deployment of E9-1-1 requires the development of new technologies and upgrades to local 9-1-1 PSAPs, as well as coordination among public safety agencies, wireless carriers, technology vendors, equipment manufacturers, and local wireline carriers. The FCC established a four-year rollout schedule for Phase II, beginning October 1, 2001 and to be completed by December 31, 2005.⁵ See Appendix A for more details.

The effects of wireless phones have rippled through most regions of society - business, family, and public safety, to name a few. Over 25 percent of the 190 million annual 9-1-1 calls are now made on wireless phones.⁶ Although these phones permit emergency access from a wide range of locations, they can also degrade emergency response. It is not unusual for an urban PSAP to receive dozens of calls about a highway fender-bender, which may delay answering calls from other emergencies. Moreover, the lack of automatic location information and the inability of many individuals to describe their location add to the PSAP workload and can constrain effective response.

The most important change may well be in societal expectations. America is a mobile society; we travel with our cell phones and expect to be able to use them in most cities, counties, and states. What is, and remains, a fundamentally local service - a local call to a local emergency responder - now has regional and national implications because of wireless technology. The majority of wireless phone users believe that a cellular 9-1-1 call provides the same capability as a wireline call. And once they do receive wireless E9-1-1 service in their home region, they most likely will expect it from anywhere that they use the same phone.

1.2 Current Roles and Responsibilities for E9-1-1

The key service providers in the current E9-1-1 system are incumbent or competitive local exchange carriers (ILEC/CLECs), the PSAPs, and the wireless carriers. Each of their roles is summarized below.

ILEC/CLECs. These wireline providers own and operate the physical infrastructure to connect the phone customer with the corresponding PSAP. In the case of 9-1-1 calls, the ILEC/CLEC determines a fixed location (address) for the caller using a Master Street Address Guide (MSAG), determines the proper Public Safety entity (jurisdictional boundaries) through use of a 9-1-1 database, and extracts the caller's phone number for the PSAP. The call is forwarded to the PSAP through a selective router, along with the caller address and call-back information. In many instances the tasks of associating a telephone number with an address and identifying the appropriate PSAP servicing that address are supported by third party service providers.

PSAPs. There currently are more than 5000 PSAPs in the United States. PSAPs are responsible for answering initial 9-1-1 calls and, based upon the nature of the call, overseeing the dispatch of the appropriate emergency services (i.e., fire and rescue, EMS, police, or others). Their operations are influenced by many factors including legislative mandates, complex dispatch boundaries for emergency service providers, agreements for providing backups to adjacent jurisdictions, and the emergency responder resources they can call upon. Technologies used by the more advanced PSAPs include dedicated communications lines to the 9-1-1 database and the selective router, computer-aided dispatch (CAD) terminals, and map database systems for locating 9-1-1 calls within their jurisdiction.

Wireless carriers. There are 6 major wireless carriers and approximately 100 small independent carriers providing wireless mobile phone services in the United States. The major carriers have adopted different technologies for their air interface and also have selected different handset location technologies to support implementation of Phase II WE9-1-1. The three air interface technologies are GSM, IDEN, and CDMA; however some carriers still support an analog network. In general, the smaller carriers intend to follow the lead of the major carriers in the implementation of handset location technologies. The particular air interface has consequences on the available position determination techniques and accuracy. With the increase in wireless services and Phase II, PSAPs may need to have an indication of the caller position accuracy to assist in the dispatch of emergency response assets.

1.3 Major Factors Affecting Implementation

The groundwork for national implementation of WE9-1-1 has been laid. An FCC rule established a compliance schedule for wireless carriers and defined the needs for preparing the PSAPs. What remains is to enable the public safety community, the wireless industry, and State and local governments to collaborate on implementation approaches and to provide technical support for PSAP preparation. The primary barriers to effective implementation are primarily non-technical, such as funding, public safety readiness, and jurisdictional coordination. The DOT and other organizations are sponsoring activities to overcome these barriers. Appendix B summarizes a few of these initiatives.

A DOT-sponsored Expert Working Group developed a comprehensive set of wireless E9-1-1 implementation barriers. This document is provided in Appendix C.

2 Current Technical Challenges

2.1 Caller Location

There are several different techniques that can be used to locate a wireless handset. The key challenges are accuracy, response time, and signal penetration in buildings.

Network-based solutions will work with existing handsets by locating them based on characteristics of their transmission. Handset-based solutions mostly rely on GPS, although modified handsets can be made capable of computing location based on time of signal arrival. Network-based techniques generally lack sufficient accuracy, while GPS handset solutions must address slow position determination. Network-assisted GPS provides the most accurate solution for the most common location techniques under consideration.

In addition, there are several other approaches identified for caller location; techniques ranging from use of digital television (DTV) signals to the application of Wi-Fi systems in buildings or campuses. Both techniques have attractive features; a predominant one is the ability of the signals to reach callers within large buildings or structures which is a problem for unassisted GPS. A brief description of some of the location techniques can be found in Appendix D.

Response time is an issue for GPS-handsets. When a caller places a 9-1-1 call via a wireline phone, the telephone address and call-back number are displayed on the PSAP call-taker's console within seconds (the address may even be displayed before call pickup). For GPS capable cell phones, there is a potential problem in processing caller location in time to display this information at the PSAP in an effective manner. GPS receivers require an initialization period after they are activated, in which case the actual location would not be available for up to 45 seconds.⁷ To address this potential delay, wireless carriers using GPS location solutions are adopting an assisted GPS system in which the cell towers provide ephemeris and other receiver-generated information for a rapid initialization for the GPS handset. This solution may be adequate to support the timely provision of caller location to the PSAP.

2.2 Safety Telematics

Telematics service providers such as OnStar, ATX, and Cross Country communicate with PSAPs on behalf of clients who are involved in accidents or other emergency situations. The key challenges are linking to a local 9-1-1 network from long distance and transferring data into the PSAP's system.

More than 2.5 million vehicles equipped with automatic crash notification (ACN) systems are operating in the United States, a figure expected to grow to 10 million by 2005. Today, when an ACN-equipped vehicle crashes, vehicle identification, location and crash severity are automatically relayed to the service provider's response center. At that point, the response center calls the PSAP closest to the emergency via a non-9-1-1 administrative line and reads information from the display monitor for the other to re-enter at a remote location. This sort of alarm notification has, by default, followed the time-honored methods followed by the alarm industry. Even though the originating equipment may be quite sophisticated, and the response center might be highly automated, the actual alarm notification to the PSAP would work quite well over the primitive telephone systems of the 1920's. That weak link is prone to the same problems of any verbal relay system, namely misinterpretation, misrouting, and mistakes of omission. Although the delay in communicating from the response center to the PSAP is generally brief, any delays can be crucial for severely injured persons.

A new generation of ACN systems will be introduced in some 2004 automobiles. While current systems are activated upon deployment of the airbag, the new systems will have sensors capable of measuring the direction and magnitude of impact, and will be able to provide more information about the crash dynamics-a critical set of information for the emergency responders. Efforts are underway to enable response centers to directly call into the appropriate PSAP's 9-1-1 network and automatically transfer crash data directly to the 9-1-1 call taker's computer screen.⁸

2.3 Internet and Other Non-Traditional Access

The increasing public mobility and reliance on wireless devices will usher in more and more third party intermediary services, such as safety telematics described above. The challenge is to effectively integrate these services into the 9-1-1 infrastructure while retaining the unique features of 9-1-1 services. Traditional 9-1-1 network components such as selective routers and database management hardware/software platforms may require new standards to accommodate these non-traditional 9-1-1 voice and data elements.⁹

IP telephony¹⁰ (transmission of voice over a packet network) is a growing service that raises a number of 9-1-1 issues. Since the usual Public Switched Telephone Network (PSTN) resources are bypassed when using IP, location identification is a key problem with this mode of operation. The term "voice over IP" (VoIP) derives from the VoIP Forum, an effort by major equipment providers, including Cisco, VocalTec, 3Com, and Netspeak to promote the use of ITU-T H.323, the standard for sending voice and video using IP on the public Internet and within intranets.¹¹ Currently, unlike traditional phone service, IP telephony service is relatively unregulated by government. FCC has indicated that it does not plan to regulate connections between a PSTN and an IP telephony service provider.¹²

3 Future Technologies and 9-1-1 Implications

3.1 New Automatic Alerting Devices

A growing number of security and alarm services provide support to homeowners, the elderly, and persons with medical conditions, to name a few. In the future, alerts will likely be generated by PDAs, wearable computers and even-implanted devices. PSAPs are well-situated to receive alarm notifications from telephone callers, and are becoming adept at utilizing enhanced information about callers gleaned from telephone billing databases and handset tracking systems. However, they are not well equipped to apply similar technology to calls that originate from non-traditional sources. There is a general concern about the increasing demands that will be placed upon the call takers and responder community, as well as the reliability of the alarm systems which trigger the call.

The current technical challenges are similar to the ones noted above for safety telematics. Future challenges may stem from the proliferation of these wireless devices, the diverse types and formats for data such as images and video, and the corresponding expectations for the public emergency communications system.

3.2 Pace of Change in Commercial and Public Communications Technologies

Wireless carriers are in a continuing process of expanding coverage and upgrading the types of services provided. An important issue is the economic and technical implications for public 9-1-1 network and emergency service delivery, as PSAP infrastructure is generally expected to have a longer life cycle than commercial systems. The challenges are to continue to deliver 9-1-1 services to all callers, while retaining appropriate previous capabilities and reliability. Service parity remains a basic objective-every potential 9-1-1 caller should have the same likelihood of a successful 9-1-1 call connection, regardless of the source of the call, whether from an ILEC, an ISP, or a wireless carrier.¹³

If planned appropriately, future 9-1-1 networks should be able to provide enhanced services enabled by commercial networks and services. For example, migration of the current circuit-switched telecommunications network to a broadband packet-switched network may resolve some of the telematics and alert device access issues.

4 Summary

One of the great strengths of our Nation is its technological expertise. A fundamental reexamination of the technological approach to E9-1-1 may reap large rewards as our public emergency network struggles to accommodate the challenges of wireless E9-1-1 along with new security concerns. Some new concepts may provide solutions to near-term issues; others may lay a foundation for longer-term progress.

As we decide upon our future path, we must strive to ensure that these innovative technologies will enhance the effectiveness of the 9-1-1 system and reduce the complexity, expense, and time required for future service deployments. And we must guarantee that future 9-1-1 system designs are sufficiently versatile to accommodate both individual emergency access and response to mass casualty events

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