Intelligent Reflecting Surfaces for Secure Wireless Communications

Intelligent reflecting surfaces (IRSs) represent an emerging paradigm in the design of secure wireless networks, whereby a planar array of passive elements dynamically adjusts the propagation of electromagnetic waves. By tuning the phase shifts and, in some designs, the amplitude of each meta-surface element, an IRS can reinforce desired links, nullify interference, and degrade the signal quality at unintended recipients. This reconfigurable environment augments conventional cryptographic techniques by embedding physical layer security directly into the propagation medium, thus safeguarding data confidentiality against eavesdroppers. Recent advances have demonstrated the feasibility of integrating IRSs into multiple-input multiple-output (MIMO) and multiple-input single-output (MISO) systems, enabling joint optimisation of transmitter beamforming and IRS phase profiles to maximise secrecy rates. Moreover, the introduction of artificial noise, simultaneous wireless information and power transfer (SWIPT), and machine-learning-driven phase-shift design has broadened the applicability of IRS-aided security to Internet of Things (IoT) networks, millimetre-wave channels and forthcoming 6G deployments. Despite promising performance gains in spectral and energy efficiency, challenges remain in acquiring accurate channel state information, handling discrete control of reflecting elements and solving highly non-convex optimisation problems. Research continues to explore robust and low-complexity algorithms, hardware realisation of large-scale surfaces and integration with advanced modulation and coding schemes. The global significance of IRS-based security is reflected in its capacity to transform legacy infrastructures into programmable, privacy-aware communication platforms without onerous hardware retrofits.

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Intelligent Reflecting Surfaces for Secure Wireless Communications publication trend

The graph below shows the total number of articles in intelligent reflecting surfaces for secure wireless communications across all publications each year (not limited to Nature Index journals).

Technical terms

Intelligent reflecting surface (IRS): A programmable array of passive elements that control phase and amplitude of incident waves to shape wireless propagation.

Physical layer security: Techniques that exploit channel characteristics and signal processing to protect data confidentiality without relying solely on encryption.

Secrecy rate: The maximum data rate at which information can be reliably transmitted to an authorised receiver while remaining confidential from eavesdroppers.

Beamforming: The process of adjusting the amplitudes and phases of transmit signals across multiple antennas to direct energy toward intended users.

Artificial noise: Deliberately injected interference designed to degrade the reception quality at non-intended receivers without affecting legitimate users.

Channel state information (CSI): Knowledge of the propagation characteristics between transmitter, surface and receiver used to optimise signal processing and phase adjustments.

References

1. Intelligent Reflecting Surface: A Programmable Wireless Environment for Physical Layer Security. IEEE Access (2019).
2. Intelligent Reflecting Surface Aided Multigroup Multicast MISO Communication Systems. IEEE Transactions on Signal Processing (2020).
3. Artificial-Noise-Aided Secure MIMO Wireless Communications via Intelligent Reflecting Surface. IEEE Transactions on Communications (2020).
4. Intelligent Reflect Surface Aided Secure Transmission in MIMO Channel With SWIPT. IEEE Access (2020).
5. Phase Shift Design in RIS Empowered Wireless Networks: From Optimization to AI-Based Methods. Network (2022).
6. Physical-Layer Security Improvement with Reconfigurable Intelligent Surfaces for 6G Wireless Communication Systems. Sensors (2021).
7. Wireless Secure Signal Transmission for Distributed Intelligent Surface-Aided Millimeter Wave Systems. IEEE Access (2020).
8. Multitask learning-based secure transmission for reconfigurable intelligent surface-aided wireless communications. ICT Express (2022).