Location Pattern Matching (LPM)

The wireless phone’s signal is received at various antenna sites equipped with special gear. The receivers send the caller’s voice call to the mobile switch, where sophisticated equipment analyzes the acoustic radio signal, and then compares it to a database of standard signal characteristics. These characteristics include signal reflections (multipath), echoes and other signal “anomalies”. According to U.S. Wireless, the only supplier of gear for this technique, when a computerized match is made, the location of the caller can be determined within the FCC’s requirements. The technique is effective in urban environments that include tall buildings and other obstructions, where other techniques might not succeed. The caller’s voice call and the latitude and longitude are then sent to the PSAP for use by the dispatcher. LPM works with any phone – digital, analog, TDMA, GSM, CDMA, etc.




Source: http://www.911dispatch.com/911/lpm.gif

Wireless Location Signatures

These methods compare the radio signal received to a database of standard signal characteristics, such as reflections and echoes. Using this information from several cell site receivers, the caller location can be computed and sent to the PSAP. This technique works best in urban environments where lots of structures exist to provide the needed reflections. It works with any phone – digital, analog, TDMA, GSM, CDMA, etc.

A key player in the field of Wireless Location Signatures (WLS) is Polaris Wireless. To learn more about their WLS offerings, check out http://www.polariswireless.com/our-technology

Uplink Time Difference of Arrival (U-TDOA)

This is sometimes referred to simply as Time Difference of Arrival (TDOA). Time Difference of Arrival relies on the fact that each cell site is generally a different distance from the caller and that signals travel with constant velocity. Therefore, each signal arrives at the cell site at slightly different times. Using these properties, a signal defines a locus of points on a circle around a base station on which a mobile could be located. Then, using synchronized receivers, the times can be compared and a latitude and longitude can be computed and sent to the PSAP. At least three different receivers are needed for TDOA to work. TDOA works with any handset – digital, analog, TDMA, GSM, CDMA, etc.

Source: http://www.iwi.uni-hannover.de/lv/ucc_ws04_05/riemer/pic/tdoa.gif

Location Technologies (Angle of Arrival)

Location Technologies (Angle of Arrival): Known as AOA, Angle of Arrival technology measures the direction of arrival of the caller’s signal (generally at least three measurements are needed) at different cell sites. Each cell site receiver sends this direction information to the mobile switch where the angles are compared and the latitude and longitude of the caller is computed and sent to the Public Safety Answering Point (PSAP).

PSAP: Public Safety Access Points are customarily segmented as “primary”, “secondary”, and so on. The primary PSAP is the first contact a 911 caller will get. Here, the PSAP operator verifies or obtains the caller’s whereabouts (called locational information), determines the nature of the emergency and decides which emergency response teams should be notified. Automatic Location Information (ALI) contained in a database, provides supplemental information for purposes of locating the caller, determining if hazardous materials are located at the subject, and so on. In some instances, the primary PSAP may dispatch aid. In most cases, the caller is then conference or transferred to a secondary PSAP from which help will be dispatched. Secondary PSAPs might be located at fire dispatch areas, municipal police force headquarters or ambulance dispatch centers. Often the primary PSAP will answer for an entire region.

Source: http://www.911dispatch.com/911/aoa.gif

Location Services

Cellphone carriers will soon be able to figure out, within 100 meters where you, a cellphone user, are. The first application of this technology is called Emergency Location Services (or E911). What this means is that if you dial 911 in the United States on your cellphone, the operator will know where you are and be able to send help. There are two basic technologies currently being adopted; E-OTD (Enhanced Observed Time Difference) uses a software-enabled cellphone handset and cell sites to calculate your location. GPS (Global Positioning Systems) relies on a chip being installed in the cellular phone and orbiting satellites to determine position. From October 1, 2001, the FCC mandated 50% of all the new cellphone activations in the United States should be equipped with location services.

Within the two broad categories of cellphone location technology, there are a number of technologies available for determining a caller’s location after initiating a 911 call from a mobile handset, but the state of their development differs. We will explore a partial list of these in the next few days. Stay tuned!

Location Tracking

Vehicle Location Tracking Devices (VLD) are products targeted at the mobile fleet/vehicle management space. Weighing less than eight ounces, they can be installed in almost any vehicle including: automobiles; construction equipment; trucks; buses; motorcycles or even boats. When used with a carrier-grade server, it allows users to track the locations of specific vehicles equipped with these devices, via the Internet. A company called Paradigm Advanced Technologies, Inc. has licensing rights to a wireless location patent covering apparatus and method of transmitting position information from satellite navigational signals (like GPS) over cellular systems to a base unit, and displaying the location of a person object so equipped. Paradigm owns PowerLOC Technologies, Inc. which anticipates providing a comprehensive range of L-Commerce and L-Business products and services including a family of proprietary wireless-location devices for this industry and for location-based service providers (LSPs) in particular.

Location Based Services (LBS)

Location Based Services enable personalized (customized) services to be offered based on a person’s (or item’s) location. Services include areas of security, fleet and resource management, location based information, vehicle tracking, person-to-person location and messaging applications. To enable these services, there are a number of different technology layers that need to be coordinated on a network. These technologies include Applications, Middleware, Determination technologies and associated Silicon and Intellectual Property (IP).

Some examples of location-based services are:

• Requesting the nearest business or service, such as an ATM or restaurant
  
• Turn by turn navigation to any address
  
• Locating people on a map displayed on the mobile phone
  
• Receiving alerts, such as notification of a sale on gas or warning of a traffic jam
  
• Location-based mobile advertising
  
• Asset recovery combined with active RF to find, for example, stolen assets in containers where GPS wouldn't work
  

Source: http://en.wikipedia.org/wiki/Location-based_service

Source: http://www.watblog.com/wp-content/uploads/2008/04/a-gps-944.jpg