1. Field of the Invention
This invention relates to a system for monitoring the movement of mobile communication devices, and to a method of monitoring the movement of mobile communication devices.
2. Discussion of Related Art
Currently in areas where large numbers of people congregate it may be advantageous to know the paths people take through the area. However, the mobile telephone network operators can only calculate the position of a mobile device to within several hundred meters unless the people being tracked carry extra equipment. This path information can currently only be accurately gathered manually, which is time consuming, expensive and error prone.
Numerous prior publications address mobile device tracking or monitoring, but all of them require the use of special hardware or software on the mobile device. In the field of shopping, U.S. Pat. No. 5,295,064 outlines a method to track shoppers by adding geolocation hardware to shopping carts, which not only makes the trolleys much more expensive but would be unable to track the shoppers who do not use a shopping cart.
In the more general field of mobile device tracking there are also a number of prior publications, but again they all require some interaction with the mobile device. In U.S. Pat. No. 6,716,101, a paging signal is sent out to a mobile device and its response is used to calculate its position. This not only has the disadvantage of working only with devices that offer such paging facilities, but it also requires the transmitting of the paging signal, which could interfere with other communications. In U.S. Pat. No. 6,246,882, a method of using specialised mobile devices which transmit a position signal is suggested. This will only give a useful indication of the movement of a group of people if significant numbers of people within that group have such specialised devices.
In conclusion no monitoring device previously suggested allows the passive monitoring of peoples' movement, without the defect of requiring the people being monitored to carry specialised or adapted hardware.