Artificial Noise Versus Artificial Noise Elimination: Redefining Scaling Laws of Physical Layer Security
This work addresses the problem of maintaining secure wireless communications against advanced eavesdropper countermeasures, though it is incremental as it builds on existing AN and ANE strategies.
The paper investigates how artificial noise elimination (ANE) affects secrecy rates in wireless physical-layer security, establishing scaling laws that reveal constraints on antenna configurations and showing that secure communication may fail if the eavesdropper has over twice as many antennas as the transmitter.
Artificial noise (AN) is a key physical-layer security scheme for wireless communications over multiple-input multiple-output wiretap channels. Recently, artificial noise elimination (ANE) has emerged as a strategy to mitigate the impact of AN on eavesdroppers. However, the influence of ANE on the secrecy rate when counteracting AN has not been investigated. In this paper, we address this issue by establishing scaling laws for both average and instantaneous secrecy rates in the presence of AN and ANE. Based on the scaling laws, several derived corollaries provide insights into the mutual constraints between the number of transmit antennas, receive antennas, and antennas at eavesdroppers, revealing the interplay between these factors. A key corollary reveals that when the eavesdropper possesses more than twice as many antennas as the transmitter, secure communication may no longer be guaranteed. Additionally, by comparing scenarios where ANE counteracts AN with those where AN is not employed, this study identifies sufficient conditions under which AN remains effective. Finally, the derived secrecy rates provide guidelines for system design, even in the presence of advanced ANE countermeasures implemented by the eavesdropper.