As the demand for automatic location identification for cell phones grows, mostly due to legislation throughout North America that requires a system for emergency responders to easily locate distressed callers, the technologies for these location determination methods continue to evolve.

 

The idea that the world’s communications networks increasingly are going mobile –  a ubiquitous, anytime, wireless connected world where no one needs to be tethered to a desk – has become a reality through emerging WiFi (News - Alert) and WiMax networks that enable anywhere, anytime voice services and network connectivity.

 

And in this developing brave new world where just about anyone is a click away, a complication has arisen: How can we locate users of these devices? Because, wherever someone has the ability to connect to the Internet, they also have the ability to place an emergency call.

 

The key to any emerging location determination methods is Wired and Wireless IPT Endpoints. This conclusion has become even clearer as more legislation has popped up throughout North America mandating the implementation of such a system across the country.

 

In fact, VoIP clients from Microsoft, Cisco and others that employ Session Initiation Protocol (News - Alert) (SIP) have already brought universal, standards-based IP telephony to handhelds and laptops.

 

“Location determination and conveyance has to keep pace with these rapid advances in real-time voice communications,” said Bill Mertka, vice president of Product Development at RedSky (News - Alert).

That is because providing accurate, seamless and transparent endpoint location data will be required if Emergency Calling Services (ECS) and other location-based services (LBSs) are to keep pace with network and telephony advancements, according to a recent whitepaper from RedSky.

 

The Chicago-based company’s whitepaper also discusses Emergency Calling Services as a location-based service and explains current and emerging technologies used to track IPT endpoint location.

 

Currently, location determination for IPT clients operating on wired Ethernet networks is relatively straightforward and companies such as RedSky already have solutions that address the location issues surrounding the movement of these IPT endpoints. On the immediate horizon, said Mertka, is the introduction of solutions that track the location of users connected to wireless LANs or WLANs in these environments.

 

These future capabilities include the “serving up” of location information from a network-attached location information server (LIS), operated by the access provider or the enterprise. Wired and Wireless IPT endpoints will be a focal point.

 

 

The E911 system developed in the 1970s was designed and optimized to provide caller location information for police, fire and medical emergency services. In this sense, E911 was the first location-based service.

 

For nearly 25 years, the system functioned effectively for several reasons including the fact that telephone endpoints did not move. Residential callers were connected to telephone company central offices through wires that were routed through a circuit switch. This made it relatively easy for emergency services units to pinpoint a caller’s location through the use of a unique telephone number assigned by the phone company.

 

The advent of mobility – cell phones, PDAs, laptop computers, Voice over IP (VoIP) –challenged this system and necessitated an upgrade to ensure 9-1-1 calls were able to be located.

  

“As telephony systems enable endpoints that can operate from anywhere, at anytime, it drives the requirement for real-time endpoint location determination (LD) systems that can support both emergency calling and other location-based services,” said Mertka.

 

And those endpoints include both wireless and wired.

 

Location Determination for Wired IPT Endpoints

 

For wired IPT endpoints connected to wired Ethernet networks, location determination can be handled by straightforward network location mapping methods.

 

For example, RedSky cites, when an IP phone plugs into the network it registers with the call processing server (or with a SIP proxy server in the case of SIP-enabled endpoints). A LIS connected to the enterprise network can use this registration event to trigger a network switch query to find the new switch port to which the phone is connected.

 

This process uses an SNMP query of a Local Area Network (LAN) switch Management Information Base (MIB) table to determine the connecting port.. Once the location of the phone is known, RedSky software ensures that the phone will send out the appropriate emergency location identification number (essentially a 10-digit number used to identify and call back the phone for emergency calling purposes) in case it dials 911.

”Development of an accurate and up-to-date wiremap of the enterprise network is a prerequisite to the sound functioning of the system, but once this has been developed, IPT endpoints can move anywhere on the network and their location can be determined within seconds,” said Mertka.

 

Location Determination for Wireless IPT Endpoints

 

Location information for IPT endpoints that connect to enterprise resources via WiFi LAN networks can be determined in a similar manner. Registration events that occur when a wireless endpoint connects to a WiFi network, can be detected by monitoring the wireless access point or its controller or through a notification from IP call servers or SIP proxies.

 

Mertka says the registration event is designed to trigger a query of the relevant network elements to determine what devices are connected to which access point(s). If the location of the access points are known, systems like RedSky’s can ensure that the call server sends out the appropriate emergency location identification number.

“The only additional consideration here is that the endpoint location is essentially that of the location of the access point even though the wireless IPT endpoint can be anywhere within the transmission radius of the access point, which is typically 60 – 150 feet,” said Mertka. “More precise location, down to 3 meters, can be achieved by deploying sensor networks that work in conjunction with the wireless access points.”

 

According to the company’s whitepaper, having the ability to accurately locate an IPT endpoint on a WiFi network is important to users for several reasons:

 

• Dual-use phones that connect seamlessly to either cellular or WiFi networks are starting to be deployed. Automatic location determination is needed when a phone transfers to a WiFi network from a cellular network so that its location can be identified and the user provided with ECS/E911 service.

• The technology that would be used to automatically determine endpoint locations on campus WiFi networks also enables location determination of IPT clients using metro-wide WiFi or WiMax networks. Client applications from companies like RedSky can leverage signal strength and triangulation measurements of WiFi signals and WiFi access point location databases to determine the precise location of these endpoints. This technology allows the IPT endpoint to be location-aware at all times. With this type of technology in place, a variety of LBS-type applications, including E911 service, can be offered by service providers to IPT endpoints.