Efficient and Secure Access to Spectrum up to THz

          Collaborative Research

Edward Knightly, Rice University and Dan Mittleman, Brown University

NSF-1923782 and NSF-1923733



Since the days of Marconi, critics complained that wireless transmission lacked security and was so slow that a boy on a pony would be a faster way to transmit a message, as Lord Byron famously quipped in 1898. Over a century later, terabit-per-second links in terahertz (THz) scale spectrum are around the corner and highly directional beams have been decreed secure by design. However, even THz links can become “too slow” if they suffer from outages while repeatedly re-aligning beams for mobile clients. Likewise, while 60 GHz bands have been lauded for their improved security, unfortunately, even pencil-beam THz-scale links can be vulnerable to agile eavesdroppers. Consequently, this project targets to design, implement, and experimentally explore proof-of-concept systems to realize a WLAN architecture with efficient and secure access to spectrum from 100 GHz up to 1 THz and WLAN-scale range up to 120 meters. This project will build on fundamental new transmission capabilities enabled by THz-scale devices and spectrum.

Intellectual Merit:

The first project thrust will realize Leaky X-Agon, a first-of-its-kind multi-face leaky waveguide WLAN architecture. This architecture couples frequency and steering angle to provide frequency-selective adaptive beam steering enabling unprecedented spatial density of links. Moreover, a new foundation for beam steering and frequency selection is realized via transmission of a wideband “THz rainbow” on each face: by emitting different frequencies at different angles, the receiver can identify all propagation paths and their steering angles simultaneously, as opposed to time-consuming and inefficient trial-and-error testing that is commonly employed today. The second project thrust addresses security and provides experimental analysis and counter-measures for securing spectrum access from 100 GHz to 1 THz. Under a strong adversary threat model, this project thrust will develop methods using THz backscatter and THz rainbow distortion to detect and avoid objects that an eavesdropper may be using to aid interception of a transmission. Moreover, a novel absorption tuning method is proposed to tune the transmission range so that interception beyond the location of the intended receiver is not viable. Using accurate empirical models, the method will tune the carrier frequency to be close to that of a water vapor absorption resonance, yielding exquisite control of the atmospheric propagation loss, and therefore of the transmission range. All project components feature an extensive implementation and experimental plan for over-the-air experiments and validation.