A revolution in wireless security

PhD student Ghaffer Iqbal Kiani.

Wireless systems are increasingly becoming the telecommunications standard worldwide. But according to a Macquarie University postgraduate student, they’re still not safe enough.

Ghaffer Iqbal Kiani began his PhD research on wireless systems security in Macquarie’s Department of Electronics earlier this year. He says the problem with many current systems, such as mobile phone and wireless Internet Local Area Network (LAN) computer networks, is that they are vulnerable to eavesdropping.

In his article published in Pakistan’s leading English language newspaper, the Daily Dawn earlier this month, Kiani points to a revolutionary technology called Frequency Selective Surface (FSS), as one answer to creating a secure wireless system for indoor environments. Currently, mobile communication and wireless Internet LAN systems are being designed on the basis of a detailed analysis of radio frequency coverage and capacity requirements.

Tune in or tune out

The FSS concept was first observed toward the end of the 18th century when an American physicist noticed that some colors of the light spectrum were suppressed when a street lamp was viewed through a silk handkerchief. It was the first proof that non-continuous surfaces can exhibit different transmission properties for different frequencies.

Using geometric metallic shapes (like crosses, circles, hexagons and squares) as filters to pass certain frequencies and stop others, Kiani envisions manufactured panels mounted on walls of a building or pasted onto a window, either internally or externally, in the same way that household microwaves currently have hexagons or circles on the front glass to prevent harmful microwave frequencies coming out of the oven.

Many potential applications

FSS has potentially many engineering applications other than wireless network security. Uses range from radio frequency identification tags to collision avoidance systems and robotic-guided paths.

But in the day-to-day world of incessantly ringing mobile phones, the technology would be most useful to create silent zones in hospitals, theatres and other public facilities where people frequently forget to turn off their mobiles. Another timely application of FSS technology would be using it to prevent mobile phone-triggered detonations of explosive material.

Design challenges

Kiani says that one of the challenges in perfecting the use of FSS will be coming up with a design that responds to different frequencies occurring at different angles, while still allowing the electronic components (capacitors, diodes etc) within the panels to remain tunable.

Kiani has recently designed and simulated a stop band filter FSS structure for 5 GHz wireless LAN that absorbs signals rather than just reflecting them. This in turn which eliminates problems of signal overlapping and multi-path fading of the radio frequency waves. Kiani says that while the practical fabrication of this design, and verifying the simulated results, would be a real challenge, it would add knowledge to the research arena.

To read more about FSS, view Ghaffer Iqbal Kiani’s newspaper article at http://www.dawn.com/weekly/science/archive/050702/science5.htm. His PhD supervisor is Associate Professor Karu Eselle, who can be contacted at karu.esselle@mq.edu.au The Department of Electronics website is at http://www.elec.mq.edu.au

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