Johnson-Nyquist Noise for Passive Data Transmission
UW ECE alumna Zerina Kapetanovic (Ph.D. ‘22), adjusting test equipment on the UW campus. Photo by Ryan Hoover | UW ECE

Johnson-Nyquist Noise for Passive Data Transmission

Johnson-Nyquist Noise Defined

Imagine a world where the very chaos of nature becomes a conduit for information. This is the promise of Johnson-Nyquist noise, a phenomenon that's been known to scientists for nearly a century but is now finding new purpose in the realm of data transmission.

At its core, Johnson-Nyquist noise, also known as thermal noise, is the electronic noise generated by the thermal agitation of charge carriers (usually electrons) inside an electrical conductor at equilibrium. It's present in all electrical circuits and is often considered a nuisance in sensitive electronic equipment. However, this ubiquitous "hiss" of the electronic world is now being seen in a new light.

The noise is characterized by a voltage that varies randomly over time, with its power spectral density being nearly constant throughout the frequency spectrum. This "white noise" property makes it particularly interesting for certain applications, as we'll soon discover.

Some History

The story of Johnson-Nyquist noise begins in the roaring twenties, not with flappers and jazz, but in the quiet laboratories of Bell Telephone. In 1926, John B. Johnson, an American physicist, first observed and measured this random fluctuation of electric potential across a conductor.

Two years later, his colleague Harry Nyquist provided the theoretical framework to explain Johnson's observations. Nyquist's work, published in his 1928 paper "Thermal Agitation of Electric Charge in Conductors," laid the groundwork for understanding this fundamental aspect of electrical systems.

For decades, engineers and scientists viewed Johnson-Nyquist noise primarily as a limitation to be overcome. It set the lower bounds for signal detection in communication systems and influenced the design of low-noise amplifiers. But as often happens in science, what was once seen as a problem is now being explored as a potential solution.

Who is Researching Using Johnson-Nyquist Noise as a Means of Passive Data Transmission?

UW ECE alumna Zerina Kapetanovic (Ph.D. ‘22), adjusting test equipment on the UW campus. Unlike existing passive wireless and backscatter communication systems, The research team’s prototype does not depend on externally generated or ambient radio frequency signals to send and receive information. Instead, the device uses a byproduct of electrical resistance in its circuitry called “Johnson noise” to enhance energy-efficiency and transmit a wireless signal. Photo by Ryan Hoover | UW ECE

In recent years, a team of innovative researchers at the University of Washington has been leading the charge in repurposing Johnson-Nyquist noise for data transmission. Their work represents a significant shift in how we think about noise in electronic systems.

The UW team has developed a prototype wireless communication system that uses Johnson noise to transmit data without relying on conventional radio frequency signals. Their system works by modulating the microwave frequency Johnson noise emitted by an antenna, allowing them to encode bits of information.

This research is particularly exciting because it demonstrates the possibility of wireless communication without the need for active signal generation. The system operates by selectively connecting and disconnecting an impedance-matched resistor, effectively "shaping" the natural noise to carry information.

Possible Real-World Applications

The potential applications of this technology are vast and varied. Here are a few areas where Johnson-Nyquist noise-based communication could make a significant impact:

  • Medical Implants: For devices like pacemakers or neural implants, a low-power, biocompatible communication method is crucial. Johnson noise transmission could provide a way to communicate with these devices without the need for batteries or external power sources.
  • Internet of Things (IoT): As we move towards a world with billions of connected devices, energy efficiency becomes paramount. Passive communication systems based on Johnson noise could allow for ultra-low-power sensors and devices.
  • Secure Communications: Because the system doesn't generate a traditional radio signal, it could be useful for covert or secure communications where detectability needs to be minimized.
  • Space Exploration: In the harsh environment of space, where power is at a premium and radiation can interfere with traditional communication methods, a Johnson noise-based system could provide a robust alternative.
  • Environmental Monitoring: Battery-free sensors using this technology could be deployed in remote or hazardous environments for long-term monitoring without the need for maintenance.

Five Related Technologies

  • Backscatter Communication: This technique, which reflects and modulates existing radio signals, shares similarities with Johnson noise communication in its passive nature.

Courtesy of

  • Quantum Key Distribution: While operating on different principles, both this and Johnson noise communication offer potential advantages in secure communication.
  • Molecular Communication: Another novel approach to data transmission, using chemical signals instead of electromagnetic waves.
  • Acoustic Underwater Communication: Like Johnson noise communication, this technology seeks alternatives to traditional radio waves for specific environments.
  • Li-Fi (Light Fidelity): While active rather than passive, this technology similarly explores using unconventional phenomena (in this case, light) for data transmission.

Future Development & Challenges

The road ahead for Johnson-Nyquist noise-based communication is both exciting and challenging. Current prototypes have achieved data rates of up to 26 bits per second over distances of 7.3 meters at room temperature. While this is a remarkable achievement, significant improvements in data rate and range will be necessary for many practical applications.

One of the primary challenges is increasing the signal-to-noise ratio. Since the system is working with noise itself, distinguishing the intentional modulations from the background randomness requires sophisticated signal processing techniques.

Another area of development is in optimizing the frequency range of operation. The current system works in the microwave range, but exploring other parts of the spectrum could yield improvements in performance or open up new applications.

Energy harvesting is another exciting avenue for research. Since the system is already dealing with thermal energy, finding ways to capture and use this energy could lead to truly self-powered communication devices.

Lastly, as with any new communication technology, standardization and integration with existing systems will be crucial for widespread adoption. This will require collaboration between researchers, industry, and regulatory bodies.

Conclusion

The exploration of Johnson-Nyquist noise for passive data transmission represents a fascinating convergence of fundamental physics and cutting-edge engineering.

As we continue to push the boundaries of what's possible in communication technology, approaches like this – which work with nature rather than against it – may become increasingly important.

While there are certainly challenges ahead, the potential benefits in terms of energy efficiency, security, and novel applications make this an area of research well worth watching. As we move into an increasingly connected world, the quiet hiss of Johnson-Nyquist noise might just become the sound of the future.

About the co-author:

John has authored tech content for MICROSOFT, GOOGLE (Taiwan), INTEL, HITACHI, and YAHOO! His recent work includes Research and Technical Writing for Zscale Labs?, covering highly advanced Neuro-Symbolic AI (NSAI) and Hyperdimensional Computing (HDC). John speaks intermediate Mandarin after living for 10 years in Taiwan, Singapore and China.

John now advances his knowledge through research covering AI fused with Quantum tech - with a keen interest in Toroid electromagnetic (EM) field topology for Computational Value Assignment, Adaptive Neuromorphic / Neuro-Symbolic Computing, and Hyper-Dimensional Computing (HDC) on Abstract Geometric Constructs.

https://www.dhirubhai.net/in/john-melendez-quantum/

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