Cell of origin


Cell of origin is a mobile-positioning technique for finding a caller's cell location.

Overview

Crude COO positioning considers the location of the base station to be the location of the caller. This is not very accurate, as the majority of mobile network cells are projected from an antenna with a spread of 120° giving a signal coverage area with the base station at one corner, rather than the centre. Omnidirectional cells may be used in rural locations and in cities. The underlying issue is that mobile phone networks are optimised for capacity and call handling rather than locating phones.
Most commercially implemented systems rely on 'enhanced' COO. In the GSM system this relies on the fact that the phones constantly measure the signal strength from the closest 6 base stations and lock on to the strongest signal.
All networks generate 'splash maps' predicting signal coverage when planning and managing their networks. These maps can be processed to analyse the area which will be dominated by each base station and to approximate each area by a circle.
In practice a network offering location services to third parties will present an API to which queries can be sent by validated users, to which a reply will be sent comprising the centre of a circle and a radius representing the expected error.
For this reason, when precision is important COO is often used in conjunction with some other technology, such as the Global Positioning System or Time of Arrival.
COO is the only positioning technique that is widely used in wireless networks and is used for Phase 1 of 911 service in the United States.
Location service using COO have been adopted by the emergency services in many countries. Commercial services have been slower to take off than many in the industry expected. One of the first services to make widespread use of COO based mobile location was the Zingo taxi hailing system, launched in London in 2003