GSM localization is the use of multilateration to determine the location of GSM mobile phones, usually with the intent to locate the user.
Localization-based Systems can be broadly divided into:
- Network based
- Handset based
Network-based techniques utilize the service provider's network infrastructure to identify the location of the handset. The advantage of network-based techniques (from mobile operator's point of view) is that they can be implemented non-intrusively, without affecting the handsets.
The accuracy of network-based techniques varies, with cell identification as the least accurate and triangulation as the most accurate. The accuracy of network-based techniques is closely dependent on the concentration of base station cells, with urban environments achieving the highest possible accuracy.
Handset-based technology requires the installation of client software on the handset to determine its location for E-911 purposes. This technique determines the location of the handset by computing its location by cell identification, signal strengths of the home and neighboring cells, which is continuously sent to the carrier. In addition, if the handset is also equipped with GPS then significantly more precise location information is then sent from the handset to the carrier.
This technology requires the installation of client software on the mobile phone, which acts as its biggest drawback, since it's difficult to install a software on a mobile phone without the user's consent. More importantly, the software has to be compatible with various operating systems. It requires the active cooperation of the mobile subscriber as well as software that must be able to handle the different operating systems of the handsets. Typically, smartphones, such as one based on Symbain, Windows Mobile, iPhone/iPhoneOS or Android would be able to run such software.
Hybrid oositioning systems use a combination of network-based and handset-based technologies for location determination. One example would be Assisted GPS, which uses both GPS and network information to compute the location. Hybrid-based techniques give the best accuracy of the three but inherit the limitations and challenges of network-based and handset-based technologies.
Examples of LBS (Location-Based Service) technologies include:
- Cell Identification - The accuracy of this method can be as good as a few hundred meters in urban areas, but as poor as 35 km in suburban areas and rural zones. The accuracy depends on the known range of the particular network base station serving the handset at the time of positioning.
- Enhanced Cell Identification - With this method, one can get a precision similar to Cell Identification, but for rural areas, with circular sectors of 550 meters.
- U-TDOA -Uplink- Time difference of arrival - The network determines the time difference and therefore the distance from each base station to the mobile phone.
- TOA -Time of arrival - This technology uses the absolute time of arrival at a certain base station rather than the difference between two stations.
- AOA -Angle of Arrival - AOA mechanism locates the mobile phone at the point where the lines along the angles from each base station intersect.
- E-OTD -Enhanced Observed Time Difference is similar to U-TDOA, but the location is estimated using measurements made by the mobile phone, rather than by base station.
- Assisted GPS- A largely GPS-based technology, which uses an operator-maintained ground station to correct for GPS errors caused by the atmosphere/topography. Assisted-GPS positioning technology typically falls back to cell-based positioning methods when indoors or in an urban canyon environment.
- Hybrid - As mentioned above, hybrid-positioning systems use different methods depending on which signals are locally available.
Importance of GPS systems
GPS is important as it helps you to figure out where you are and where you are going when you are traveling from one place to another. Navigation and positioning are important but cumbersome activities, which GPS makes it easier. Once GPS locates your position, and then it starts tracing other factors like speed, bearing, tracks, trip distance, sunrise/sunset time, distance to destination and several other details. GPS uses 'man-made' stars as reference points to calculate positions accurate to a matter of meters. However, with recent forms of GPS you can make measurements much better than centimeter readings. So it is with the aid of GPS that you can give a unique and specified address to every square meter on the planet. So these days GPS finds its way into cars, planes, boats, construction equipments, smartphones, laptop computers and shoes (www.gpsshoe.com) and belts. In addition, GPS tracking system installed in the phone can greatly help an individual to get automated GPS information through their cell phones.
About the Author
Patrick Bertagna is the Chairman, President, CEO and founder of GTX Corp and co-inventor of the patented GPS Footwear technology (US Patent No. 6,788,200). His career spans 27+ years in building companies in both technology and consumer branded products.
In 1993 Mr. Bertagna transitioned into the world of software technology and founded Barcode World, Inc. a supply chain management application company, enabling the accurate tracking of consumer products from design to retail distribution. Within four years the company had over 450 premier branded accounts with a staff of 40 plus in the U.S., Eastern Europe and India. After selling his company Mr. Bertagna then combined his two past careers (consumer products and tracking technology) and founded GTX Corp in 2002.
Mr. Bertagna has formed alliances with Fortune 500 companies such as IBM, AT&T, Sports Authority, Federated Stores, Netscape and GE; and has been a keynote speaker at numerous industry trade shows and conferences.