Two-dimensional and high-order directional information modulations for secure communications based on programmable...

Area of Science:

• Wireless Communication
• Metasurface Technology
• Physical-Layer Security

Background:

• Conventional wireless schemes transmit data broadly, creating security vulnerabilities.
• Directional Information Modulation (DIM) offers a solution by directing signals, but existing methods are bulky, costly, and limited in modulation support.
• There is a need for efficient, compact, and versatile DIM systems.

Purpose of the Study:

• To propose a novel Directional Information Modulation (DIM) scheme.
• To overcome the limitations of existing DIM technologies, focusing on size, energy, cost, and modulation support.
• To demonstrate the feasibility of multi-directional secure wireless communication.

Main Methods:

• Development of a Directional Information Modulation (DIM) scheme utilizing a 2-bit programmable metasurface (PM).
• Implementation of a fast and efficient discrete optimization algorithm to optimize digital coding sequences for the PM.
• Experimental realization of constellation diagrams for 8 phase shift keying (PSK), 16 quadrature amplitude modulation (QAM), and 64QAM in multi-channel modes.

Main Results:

• The proposed 2-bit programmable metasurface (PM) based DIM scheme successfully overcomes the bulkiness, energy consumption, and cost limitations of prior art.
• The system effectively generates and transmits correct constellation symbols in multi-directional beams.
• Proof-of-concept demonstrations achieved accurate constellation diagrams for 8 PSK, 16 QAM, and 64 QAM.

Conclusions:

• The developed programmable metasurface (PM) based Directional Information Modulation (DIM) scheme offers a practical and efficient solution for secure wireless communications.
• This approach enables multi-directional beamforming with support for high-order modulation, enhancing physical-layer security.
• The work paves the way for endogenous secure communication systems.