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Introduction

Wireless Emergency Services (WES) refers to the use of mobile positioning technology to pinpoint mobile users for purposes of providing enhanced wireless emergency dispatch services (including fire, ambulance, and police) to mobile phone users.

While WES is a type of location-based service (LBS), it is a mandate in the United States where 911 is the official dialing pattern for fixed and mobile network access to emergency services.

US Mandate for WES

In October 1994, the Federal Communications Commission (FCC) issued FCC 94-102, with the order published in July 1996. The original order required:

• By 1^st October, 1997: Phase 0 required all 911 calls to be delivered to Public Safety Answer Points (PSAP), even for unintialized mobile devices
• By 1^st April, 1998: Phase I required mobile operators to provide a call back number and location data to PSAP
• By 1^st October, 2001: Phase II required mobile operator to provide call back number and caller location within 125 meters 67% of the time based on a root mean square (RMS*) average

The FCC later amended the location accuracy/precision requirements for phase II to the following:

• Handset based position determination equipment (PDE): 50 meters 67% of the time, 150 meters 95% of the time
• Network based PDE: 100 meters 67% of the time, 300 meters 95% of the time
• Hybrid PDE: 50 meters 67% of the time, 150 meters 95% of the time

The above requirements provide for the ability to phase in the required technology over a four year period.

The FCC recognized the fact that, generally speaking, handset based PDE (such as A-GPS) is more accurate than network based PDE. The FCC also recognizes that it will take some time for mobile operators to deploy handsets for handset based positioning. Specific accuracy obtained will be dependent on the type of mobile positioning deployed and other factors such as environmental conditions such as user distance from the location measurement units, topography, and atmospheric conditions.

Technology for US WES

In order to deploy WES in the US, mobile operators need the following:

• PDE
• Wireless 911 application
• Location manager middle-ware application
• Coordination with PSAPs regarding locations/routing to emergency service jurisdictions

WES Standards

The TIA Ad Hoc Emergency Services (AHES) committee developed a standard, which would eventually become a joint standard for US ANSI-41 and GSM deployments of WES - the J-STD-036. The J-STD-036 ultimately evolved to incorporate a mobile positioning center (MPC) that would provide the location manager middle-ware function for WES as well as commercial based LBS. Additional Wireless Intelligent Network (WIN) standards are evolving to provide additional capabilities in support of the MPC and commercial LBS.

Europe Initiative for WES

The European Commission established the Coordination Group on Access to Location Information by Emergency Services (CGALIES) with the mission to define requirements for a Pan European common location provisioning mechanism, that can be accessed and used by the European 112 community and emergency service operators. The plan is to have a system in place by 2003.

While Europe will likely use US implementations, network architecture, and standards as guide, it is probable that there will be certain differences. However, the same core technologies such as SS7 and location middle-ware shall be the same.

Additional Resources:

Books about: Location-based Services (LBS)

For more information about the mobile IN technologies behind WES, read the book Wireless Intelligent Networking published by Artech House (www.artechhouse.com).