Watching brief for Wi-Fi

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Research into using Wi-Fi transmissions as an alternative radar technology could lead to low-cost tracking and surveillance systems, according to engineers at University College, London.

Research into using Wi-Fi transmissions as an alternative radar technology could lead to low-cost tracking and surveillance systems, according to engineers at University College, London.

The UCL team claimed technical similarities between radar and Wi-Fi signals could open the way for new uses for the increasingly ubiquitous wireless networking standard.

The popularity of Wi-Fi local area networks (LANs) that allow wireless high-speed connection to the internet has meant that a growing number of buildings and public areas are being equipped with Wi-Fi access points.

According to Dr Ingemar Cox of UCL’s department of electronic and electrical engineering, this proliferation of Wi-Fi ‘hotspots’ could allow the radio system to be used for other purposes.

‘This has the potential to be very low cost, because many indoor areas, such as airports, already have Wi-Fi,’ he said. ‘What the radar will do is just piggy-back the Wi-Fi signal.’

The UCL research is at a very early stage, but Cox said that the technical obstacles should prove possible to overcome.

‘What we have realised is that the signature of a Wi-Fi signal and a standard radar signature are very similar.’

Existing radar tracking systems send a pulse towards an object, then calculate distance based on the time it takes for the pulse to be received back at its starting point. Using Wi-Fi transmissions would work in the same way, but the signal would be coming from a number of sources.

According to Cox, this might complicate the processing, but with the use of a simple receiver system the basic principles should still apply.

The Wi-Fi radar system would be used in conjunction with video surveillance cameras, detecting someone entering a room and triggering the operation of the cameras. It could also track goods and people.

A feasibility study will investigate the concept’s compatibility with the new wave of Wi-Fi 802.15 and 802.16 technologies as part of the EPSRC-funded research. If successful, a full-scale research project should follow.