A MAN working in a skyscraper has a heart attack and phones for help, but he fails to tell the emergency operator which floor he鈥檚 on. Paramedics then have to waste precious minutes searching the 40-storey building, and the man dies.
Researchers at the University of Toronto in Canada and chipmaker Intel have developed a system that they say could help prevent such deaths. Called , it can estimate the location of callers inside high-rise buildings to within two floors. If used in New York鈥檚 102-storey Empire State Building, it could cut the floor space that would have to be searched from 204,000 to 2000 square metres.
In a city, cellphones pick up signals from many tens of masts but to make a call they only use the masts sending the strongest signals. Signals can be used to triangulate a phone鈥檚 position using the three nearest masts, but it is only accurate to 50 metres and can鈥檛 distinguish between floors.
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Skyloc exploits the fact that every point in a city is bathed in a unique combination of radio signals from hundreds of masts, each at different strengths and frequencies. Skyloc uses this miasma to generate a 鈥減osition fingerprint鈥� that is unique both to the phone鈥檚 horizontal coordinates and vertical position.
On each floor of three high-rise buildings, a team led by Alex Vershavsky of the University of Toronto recorded the signals received from 29 masts. Specially developed software successfully allowed a phone to transmit these position fingerprints during calls. These were then matched against a database of all fingerprints from the building to pinpoint the caller鈥檚 floor. Vershavsky says lives could be saved if all tall buildings were 鈥渞adio-mapped鈥� and phones were programmed to transmit their position fingerprints.
Amanda Goode, a UK-based expert in cellphone forensics, sees other uses for the technology. 鈥淭he ideas behind this could be useful in kidnap or serious crime investigations,鈥� she says.
鈥淭his system could be very useful in kidnap or serious crime investigations鈥�
