Mobile positioning, which includes location based service that discloses the actual coordinates of a mobile phone bearer, is a technology used by telecommunication companies to approximate where a mobile phone, and thereby also its user (bearer), temporarily resides. The more properly applied term locating refers to the purpose rather than apositioning process. Such service is offered as an option of the class of location-based services (LBS)
Technology
The technology of locating is based on measuring power levels and antenna patterns and uses the concept that a powered mobile phone always communicates wirelessly with one of the closest base stations, so knowledge of the location of the base station implies the cell phone is nearby.
Advanced systems determine the sector in which the mobile phone resides and roughly estimate also the distance to the base station. Further approximation can be done by interpolating signals between adjacent antenna towers. Qualified services may achieve a precision of down to 50 meters[citation needed] in urban areas where mobile traffic and density of antenna towers (base stations) is sufficiently high. Rural and desolate areas may see miles between base stations and therefore determine locations less precisely.
GSM localization is the use of multilateration to determine the location of GSM mobile phones, or dedicated trackers,usually with the intent to locate the user.
Localization-Based Systems can be broadly divided into:
Network-based
Handset-based
SIM-based
Hybrid
Network-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 a mobile operator's point of view) is that they can be implemented non-intrusively, without affecting the handsets.
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One of the key challenges of network-based techniques is the requirement to work closely with the service provider, as it entails the installation of hardware and software within the operator's infrastructure. Often, a legislative framework, such as E911, would need to be in place to compel the cooperation of the service provider as well as to safeguard the privacy of the information.
Handset-based
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The key disadvantage of this technique (from mobile operator's point of view) is the necessity of installing software on the handset. 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 Symbian, Windows Mobile, Windows Phone, BlackBerry OS, iPhone, or Android, would be able to run such software.
One proposed work-around is the installation of embedded hardware or software on the handset by the manufacturers, e.g. E-OTD. This avenue has not made significant headway, due to the difficulty of convincing different manufacturers to cooperate on a common mechanism and to address the cost issue. Another difficulty would be to address the issue of foreign handsets that are roaming in the network.
SIM-based
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Hybrid
Hybrid positioning systems use a combination of network-based and handset-based technologies for location determination. One example would be some modes of Assisted GPS, which can both use GPS and network information to compute the location. Both types of data are thus used by the telephone to make the location more accurate (i.e. A-GPS). Alternatively tracking with both systems can also occur by having the phone attain his GPS-location directly from the satellites, and then having the information sent via the network to the person that is trying to locate the telephone. Services allowing such cellphone include Google Latitude. Other examples would be LTE'sOTDOA and E-CellID.
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