Location-detection technologies

Mobile phone networks, like any other network, cannot be operated unless the location of each associated device is known. That cannot be avoided. Current mobile phone networks in the UK record location in terms of cell ID. Cells are defined by base stations, also known as "radio masts" or "antennae". Each base station has an ID and defines a cell. Assuming that an omni-directional antenna is used:

  • In low message traffic areas the cell is a sphere with a radius of several kilometres.
  • In high message traffic areas, where there are more base stations, the radius falls to 150 metres or less.

(In fact, the topology of cells varies. Cells can be divided into sectors. Cells can comprise multiple micro-cells. Omni-directional antennae do not necessarily define spherical cells ...)

When a mobile phone associates with a base station, i.e. when there is at least one blob of signal on the screen, its location can be narrowed down to the given cell and the mobile phone network operators can detect the location of the phone accurately to within several kilometres in the countryside, 150 metres in the city and sometimes better.

The main location-detection technologies being used in the US and Europe are EOTD and AGPS:

While EOTD and AGPS approach greater accuracy in location-detection, other related technologies are overtaking them. 802.11 wireless networks can provide 5ft accuracy, see for example:

Ekahau's RFID products can achieve 50cm accuracy. They provide a useful starting point for comparing the various location-detection technologies. Start with those, and then try Geolocation technologies and applications for third generation wireless.

EOTD looks as though it has problems achieving accurate location-detection, AGPS seems to be well on the way and the possibility of using multi-protocol mobile phones, incorporating 802.11, looks most promising, given the growing prevalence of WiFi hotspots.

WiFi hotspots use 802.11, which operates in the unlicensed, free industrial, scientific and medical bands (ISM), and if hotspots one day achieve the coverage of mobile phone networks, can we look forward then to using voice over IP (VoIP) instead of GSM/GPRS/UMTS/CDMA, with their attendant waveband licence fees, including £22.5bn wasted on 20-year 3G licences in the UK, and saving money as a result?
Location-detection accuracy is set to grow. At the same time, people in the UK remain apparently uninterested in the privacy issues. For example, the London Congestion Charge scheme incorporates Automatic Number Plate Recognition software attached to CCTV cameras. While Ken Livingstone won Worst Public Servant at the 2003 UK Big Brother Awards and Capita won Most Invasive Company, the scheme has been declared a success and is set to be emulated all over the UK and overseas.

(The paragraphs above are adapted from a paper produced in May 2003 (para.4.6). The research has not been updated since then. Many references in the May 2003 paper have been removed, having disappeared from the web in the interim.)

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on behalf of Dematerialised ID Ltd