There are an ever-increasing number of wireless mobile devices transmitting and receiving data, even though there's only a limited amount of bandwidth available to them. In order to keep their signals from jamming one another, scientists have replicated a system used by a cave fish.
The glass knifefish, more formally known as Eigenmannia, lives its entire life in complete darkness. In order to find its way around, and to communicate with other knifefish, it emits an electrical signal. If two fish generate signals that are of a similar frequency, however, those signals will interfere with one another, causing both to jam.
In order to keep that from happening, Eigenmannia utilizes a "neural algorithm" known as a jamming avoidance response (JAR). Using this, each fish detects the electrical signals of other individuals nearby, and if the frequency of any of those signals is too close to its own, the fish will automatically adjust its signal frequency so that they don't interfere.
Led by assistant professor Mable P. Fok, a team at the University of Georgia has replicated that system using an existing optical component called a semiconductor optical amplifier (SOA).
It identifies the properties of the signal that it's emitting, then checks to see if another detected signal has the potential to jam it. If it does have that potential, then the SOA changes the frequency of its own signal, to avoid interference. It even determines if the detected signal is of a higher or lower frequency than its own, then moves its signal in the opposite direction, so that it doesn't cross the frequency of the detected signal along the way.
The scientists have successfully tested the system using jamming signals in the microwave region of the electromagnetic spectrum, typically used for local area wireless networks such as Bluetooth. They're now working on making the SOA more portable, and allowing it to respond to more than one other signal simultaneously.
"Eventually, this approach could be used to achieve effective use of the wireless spectrum by allowing wireless devices to automatically move to a frequency that doesn't interfere with other signals nearby," says Fok. "This could bring down the cost of using the wireless spectrum because service providers would not have to pay to reserve large amounts of bandwidth. This, in turn, could make it more affordable to bring mobile technology to developing countries, where it could be used to support important services such as telemedicine or distance learning."
A paper on the research was recently published in the journal Optics Express.
Source: The Optical Society
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