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Secure space–time-modulated millimetre-wave wireless links that are resilient to distributed eavesdropper attacks


As wireless networks move to millimetre-wave (mm-wave) and terahertz (THz) frequencies for 5G communications and beyond, ensuring security and resilience to eavesdropper attacks has become increasingly important. Traditional encryption methods are challenging to scale for high-bandwidth, ultralow-latency applications. An alternative approach is to use physical-layer techniques that rely on the physics of signal propagation to incorporate security features without the need for an explicit key exchange. Ensuring security through the use of directional, narrow-beam-like features of mm-wave/THz signals has proven to be vulnerable to passive eavesdroppers. Here we report a space-time modulation approach that ensures security by enforcing loss of information through selective spectral aliasing towards the direction of eavesdroppers, even though the channel can be physically static. This is achieved by using custom-designed spatio-temporal transmitter arrays realized in silicon chips with packaged antennas operating in the 71–76 GHz range. We also analytically and experimentally demonstrate the resilience of our links against distributed and synchronized eavesdropper attacks in the mm-wave band.

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Fig. 1: Physical-layer security approach to enforce intentional spectral aliasing and loss of information in the Alice-to-Eve channel by imparting it with a time-varying nature (even though it can be physically static).
Fig. 2: Measured constellation and spectrum across all the spatial angles, and security aspects of the STMA compared with a phased array.
Fig. 3: Measured constellation and spectrum across all the spatial angles, and security aspects of the STMA when modulated with a linearly time-varying frequency waveform or a chirp signal.
Fig. 4: Measured resilience against a distributed and colluding eavesdropper attack with known channel (channel inversion attack) on the presented STMA in the 71–76 GHz range.
Fig. 5: Measured resilience against a distributed and colluding eavesdropper attack in the 71–76 GHz range on the presented STMA for ML-based attacks.

Data availability

The data that support the findings of this study are available from the corresponding authors upon reasonable request.


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We would like to thank the Army Research Office, the Air Force Office of Scientific Research (AFOSR), the Office of Naval Research (ONR) and Defense Advanced Research Projects Agency (DARPA) for funding support and all the members of IMRL for technical discussions.

Author information




S.V. and X.L. conceived the experiments and design. X.L., S.V. and B.T. performed the circuit simulations, layout design and chip assembly, as well as conducted the measurements and analysed the results. K.S. supervised the experiments. S.V., X.L. and K.S. wrote the manuscript, and all the authors reviewed the manuscript.

Corresponding authors

Correspondence to Suresh Venkatesh or Xuyang Lu.

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The authors declare no competing interests.

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Peer review information Nature Electronics thanks Stepan Lucyszyn and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Venkatesh, S., Lu, X., Tang, B. et al. Secure space–time-modulated millimetre-wave wireless links that are resilient to distributed eavesdropper attacks. Nat Electron 4, 827–836 (2021).

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