We propose an artificial noise (AN) injection strategy for securing communication over finite-input intersymbol interference (lSI) channels. The technique relies on injection of colored noise whose power spectral density has the least match with the spectrum of the main channel in a certain sense. By evaluation of an achievable secrecy rate, we demonstrate that the proposed AN injection based solution results in a considerable improvement over the existing approaches, especially when the eavesdropper works at high signal-to-noise ratios (SNRs).
We propose an artificial noise (AN) injection strategy for securing communication over finite-input intersymbol interference (lSI) channels. The technique relies on injection of colored noise whose power spectral density has the least match with the spectrum of the main channel in a certain sense. By evaluation of an achievable secrecy rate, we demonstrate that the proposed AN injection based solution results in a considerable improvement over the existing approaches, especially when the eavesdropper works at high signal-to-noise ratios (SNRs).
Secure communication over a wireless channel in the presence of a passive eavesdropper is considered. We present a method to exploit the eavesdropper's inherent receiver vulnerabilities to obtain everlasting secrecy. An ephemeral cryptographic key is pre-shared between the transmitter and the legitimate receiver and is utilized to induce intentional intersymbol interference (ISI). The legitimate receiver uses the key to cancel the ISI while the eavesdropper, since it does not have the key, cannot do such. It is shown that although ISI reduces the capacity of the main channel, it can lead to a net gain in secrecy rate. The achievable secrecy rates for different ISI filter settings are evaluated and the proposed method is compared with other information-theoretic security schemes.
This paper introduces a revolutionary physical layer security paradigm: Artificial Signal Injection and Superposition (ASIS), a novel framework that actively injects carefully designed artificial signals into the communication channel, creating a superposition with legitimate user data to achieve unprecedented security guarantees. Unlike traditional physical layer security methods that rely on passive channel characteristics, ASIS actively engineers the signal space to create controlled interference that benefits legitimate receivers while confounding eavesdroppers. Our approach leverages multi-dimensional signal processing, game-theoretic optimization, and information-theoretic principles to design injection signals that are: (1) decodable by intended receivers using advanced signal separation techniques, (2) indistinguishable from noise or interference to unauthorized listeners, and (3) adaptive to channel conditions and eavesdropper capabilities. The ASIS framework provides provable security against both passive and active attacks, achieves informationtheoretic secrecy rates, and can be implemented using existing wireless hardware with firmware upgrades. Experimental results from our software-defined radio testbed demonstrate 40 dB SNR advantage for legitimate receivers over eavesdroppers, bit error rates below 10 −6 for legitimate users versus > 0.4 for eavesdroppers, and throughput improvements of 15-30% compared to conventional cryptographic approaches due to reduced overhead. The proposed system represents a paradigm shift in secure communications, moving from passive protection to active signal-space engineering for security.
This paper considers a massive MIMO network that includes one multiple-antenna base station, one multiple-antenna eavesdropper, and K single-antenna users. The eavesdropper operates in passive mode and tries to overhear the confidential information from one of the users in the down-link transmission. In order to secure the confidential information, two artificial noise (AN)-aiding schemes are proposed. In the first scheme, AN is injected into the downlink training signals to prevent the eavesdropper from obtaining the correct channel state information of the eavesdropping link. In the second scheme, AN is deployed in both downlink training phase and payload data transmission phase to further degrade the eavesdropping channel. Analytical expressions and tight approximations of the achievable secrecy rate of the considered systems are derived with taking imperfect channel estimation and two types of precoding, i.e., maximum-ratio-transmission and zero-forcing, into consideration. Optimization algorithms for power allocation are proposed to enhance the secrecy performance of the proposed AN-aiding schemes. The results reveal that deploying AN in the downlink training phase of massive MIMO networks does not affect the downlink channel estimation process at users while enabling the system to suppress the downlink channel estimation process at eavesdropper. As a consequence, the proposed AN-aided schemes improve the system performance significantly. Furthermore, implementing AN in both phases allows the considered system having a flexible solution to maximize its secrecy performance at the price of higher complexity.
We consider the problem of secure communication with multiantenna transmission in fading channels. The transmitter simultaneously transmits an information-bearing signal to the intended receiver and artificial noise to the eavesdroppers. We obtain an analytical closed-form expression of an achievable secrecy rate and use it as the objective function to optimize the transmit power allocation between the information signal and the artificial noise. Our analytical and numerical results show that equal power allocation is a simple yet near-optimal strategy for the case of noncolluding eavesdroppers. When the number of colluding eavesdroppers increases, more power should be used to generate the artificial noise. We also provide an upper bound on the SNR, above which, the achievable secrecy rate is positive and shows that the bound is tight at low SNR. Furthermore, we consider the impact of imperfect channel state information (CSI) at both the transmitter and the receiver and find that it is wise to create more artificial noise to confuse the eavesdroppers than to increase the signal strength for the intended receiver if the CSI is not accurately obtained.
For large-scale multiple-input multiple-output (MIMO) systems, antenna selection (AS) schemes are usually used to reduce hardware cost and energy consumption, in which only the antennas with low correlation each other and high gain are activated. However, such existing AS schemes may not necessarily ensure the security of information transmission when eavesdroppers are involved as the channels between legitimate users and eavesdroppers may correlate each other due to the inadequate scattering conditions in the propagation. To this end, a novel AS and artificial noise (AN) injection strategy is proposed to enhance system security. Specifically, integrating the correlation between the paths of the legitimate user (LU) and the eavesdropper with channel gains, a comprehensive metric is defined, based on which the optimal antennas used to transmit signals are obtained. Then, based on a deep Q-network (DQN), the subspaces for precoding confidential messages and injecting AN are alternately optimized to maximize the system secrecy rate. Simulation results illustrate that the proposed scheme can obtain much higher secrecy rate compared to the existing ones.
Due to the openness of wireless communication, information transmitted in the multiple access channel is vulnerable to eavesdropping by illegitimate users. Classic artificial noise-assisted schemes can improve security but are not suitable for power-constrained users. To address this problem, we propose a cross-time interference injection scheme in this paper, which improves security by introducing cross-time self-interference and inter-user interference, and does not require artificial noise. The proposed scheme exploits the properties of the Hadamard matrix and the wireless channels, so that the eavesdropping channel suffers from stronger interference than the legitimate channel. We analyze the security performance when both the legitimate receiver and the eavesdropper exploit the successive interference cancellation (SIC) scheme, including the secrecy sum rate, the secrecy capacity, and the secrecy outage probability. We further investigate the effect of the number of eavesdropper’s antennas, the number of legitimate users, and the number of time slots used by the scheme on the security performance, and obtain the corresponding relationship between these parameters when achieving a positive secrecy rate. Finally, simulation results corroborate our theoretical analysis.