Georgia researchers propose better spectrum sharing based on electric fish system

While more sharing of spectrum will be part of the future for wireless technology, plenty of concerns remain about interference and jamming. Researchers at the University of Georgia in Athens, Ga., are turning to nature to find a solution for more efficient spectrum sharing.

In a paper published in the IEEE Photonics Society Newsletter, researchers Mable Fok and Ryan Toole note the level of strain on RF networks and the susceptibility to radio interference and jamming, suggesting that nature may present a solution to the problem. The South American fish Eigenmannia uses active electrolocation to locate objects by generating an electric field and detecting distortions in the field. Naturally, the fish don't have to get a license from the FCC for their spectrum usage, nor do they rely on a centralized approach for using unlicensed spectrum.

"Instead, they have a physical neural circuit that can effectively sense the frequency of neighboring Eigenmannia and use this sense to regulate their own emitting frequency to a spectral hole that is not being used by any other nearby Eigenmannia," the researchers write. "This jamming avoidance response (JAR) in Eigenmannia makes the 'uncoordinated communication systems' among the fish possible."

Borrowing the JAR circuitry system from the Eigenmmania, the researchers say they can facilitate an uncoordinated communication system that allows automated interference mitigation while at the same time avoiding complicated changes in existing communication protocol. In nature, the fish have developed a natural system that prevents them from jamming each other's signals.

Using the example of a first responder rescue helicopter, the researchers explain that if the JAR circuitry from the Eigenmannia can be replicated, so to speak, they can facilitate an uncoordinated communication system that allows automated interference mitigation while avoiding complicated changes in existing communication protocol.

A challenge lies in the fact that the Eigenmannia has a discharge frequency of hundreds of Hz and is only capable of operating in that frequency range; however, "in our communication system, a much wider frequency band from MHz to tens of GHz is required," the researchers said. "Here is where photonics plays an important role in a practical JAR system."

The JAR algorithm in Eigenmannia is best suited for small-scale systems where the frequency channels are not pre-allocated or systems where frequencies must be hopped dynamically over time. "The JAR suggests a fundamental change in how the detection and transmission in spectral holes in uncoordinated communication systems could be performed," the researchers said. "Rather than working at the protocol level or network management level, dealing with the problem at the physical layer by mimicking the JAR design that already exists in nature could be an effective and practical solution."

According to UGA Today, the next steps in the project include building a physical prototype of the JAR circuit. The researchers also need to evaluate the best way to handle a large number of competing wireless devices in the system.

For more:
- see this UGA Today article
- see this IEEE Photonics Society newsletter

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