Artificial Noise Scheme Research Articles

Pilot-Based Codebook Non-Orthogonal Artificial Noise Schemes for Physical Layer Security: Secrecy Capacity Optimization Under Unknown Eavesdropper Channels

Pilot-Based Codebook Non-Orthogonal Artificial Noise Schemes for Physical Layer Security: Secrecy Capacity Optimization Under Unknown Eavesdropper Channels

Secure short-packet transmission in uplink massive MU-MIMO assisted URLLC under imperfect CSI

Ultra-reliable and low-latency communication (URLLC) is still in the early stage of research due to its two strict and conflicting requirements, i.e., ultra-low latency and ultra-high reliability, and its impact on security performance is still unclear. Specifically, short-packet communication is expected to meet the delay requirement of URLLC, while the degradation of reliability caused by it makes traditional physical-layer security metrics not applicable. In this paper, we investigate the secure short-packet transmission in uplink massive multiuser multiple-input-multiple-output (MU-MIMO) system under imperfect channel state information (CSI). We propose an artificial noise scheme to improve the security performance of the system and use the system average secrecy throughput (AST) as the analysis metric. We derive the approximate closed-form expression of the system AST and further analyze the system asymptotic performance in two regimes. Furthermore, a one-dimensional search method is used to optimize the maximum system AST for a given pilot length. Numerical results verify the correctness of theoretical analysis, and show that there are some parameters that affect the tradeoff between security and latency. Moreover, appropriately increasing the number of antennas at the base station (BS) and transmission power at user devices (UDs) can increase the system AST to achieve the required threshold.

Secure transmission in wireless ad-hoc networks without CSI at the destination

Due to the openness of wireless communication, the transmission in ad hoc networks is vulnerable to eavesdropping by illegitimate users. The traditional work generally assumes that both the transmitter and the receiver know the channel state information (CSI) of the legitimate channel, but less consideration is given to the scenario where the receiver does not know the CSI. In order to improve the security performance in this scenario, we propose novel transmission schemes by introducing artificial noise or self-interference across time. The artificial noise scheme can improve security significantly but consumes remarkable power, so we instead fuse multiple signals through a Hadamard matrix to actively introduce self-interference. It turns out that the latter scheme has obvious advantages since it improves security and saves power simultaneously. We analyze the achievable secrecy rate of the proposed scheme, and exhibit simulation results to verify the theoretical analysis.

Multi-Antenna Jammer-Assisted Secure Short Packet Communications in IoT Networks

In this work, we exploit a multi-antenna cooperative jammer to enable secure short packet communications in Internet of Things (IoT) networks. Specifically, we propose three jamming schemes to combat eavesdropping, i.e., the zero forcing beamforming (ZFB) scheme, null-space artificial noise (NAN) scheme, and transmit antenna selection (TAS) scheme. Assuming Rayleigh fading, we derive new closed-form approximations for the secrecy throughput with finite blocklength coding. To gain further insights, we also analyze the asymptotic performance of the secrecy throughput in the case of infinite blocklength. Furthermore, we investigate the optimization problem in terms of maximizing the secrecy throughput with the latency and reliability constraints to determine the optimal blocklength. Simulation results validate the accuracy of the approximations and evaluate the impact of key parameters such as the jamming power and the number of antennas at the jammer on the secrecy throughput.

Secure spatial modulation based on two-dimensional generalized weighted fractional Fourier transform encryption

In this paper, a two-dimensional generalized weighted fractional Fourier transform (2DGWFRFT) and constellation scrambling (CS)-based secure spatial modulation (SM) scheme, called 2DGWFRFT-CS-SM, is proposed to enhance the physical layer security (PLS) of the wireless communication system. The proposed scheme is executed by two steps. In the first step, 2DGWFRFT is implemented as the security kernel for PLS provision. In the second step, the parameters of 2DGWFRFT, regarded as the encryption core, control the antenna number rotation to further enhance the security of the SM modulation symbol. Both the 2DGWFRFT signal generation strategy and the SM system including the transfer process have been elaborated to depict the security mechanism of the proposed scheme. Moreover, we give a key extraction algorithm utilized to generate the parameters, which can help scramble the antenna serial number. From the perspective of signal characteristics, the uniqueness of variation in the constellation has been investigated to outperform other cryptography-based encryption algorithms. Finally, the secrecy rates and the energy efficiency of our proposed scheme are theoretically analyzed and evaluated via Monte Carlo simulations, demonstrating that the proposed scheme can achieve a much higher secrecy capacity than artificial noise schemes without requiring additional jamming power consumption and myriad costs of hardware.

Improving Physical Layer Security in Vehicles and Pedestrians Networks With Ambient Backscatter Communication

Autonomous driving is considered one of the killer technologies in the intelligent era. The information transmission between autonomous vehicles and pedestrians (V2P) is very important to reduce the number of road accidents. Ambient backscatter communication (AmBC) technology can be used to increase the vehicle (or driver) awareness regarding the presence of pedestrians in a crosswalk to realize short-distance transmission of emergency messages. On the other hand, highly secure transmission in V2P networks is required to assure the broadcasting of emergency messages. However, the artificial noise scheme by an additional noise source to improve the physical layer security (PLS) is not suitable due to the dynamic vehicles. Therefore, in this paper, we propose a source-noise assisted AmBC transmission scheme in the V2P system, in which the noise is created by the ambient radio frequency (RF) source to improve the PLS performance. The closed-form expressions for the outage probability of the legitimate user and the intercept probability of eavesdropper are derived. Finally, the diversity gain performance of the system is studied by analyzing the asymptotic behaviors. The theoretical and simulation results show that the proposed scheme improves the system security performance at the expense of system reliability by utilizing the proposed source-noise aided scheme in the V2P network. Besides, the optimal reflection coefficient is related to the power allocation ratio for the signal of the reader and interference noise. The different reflection coefficient is required for achieving the best system performance under different power allocation ratios. Moreover, the results also show that there are error floors for the outage probability, depending on the reflection coefficient. Furthermore, the performance results show that the intercept probability will significantly decrease when the outage probability is fixed in the proposed scheme.

Artificial Noise Aided Secure Communications for Cooperative NOMA Networks

Non-orthogonal multiple access (NOMA) has been envisioned as a promising multiple access technique to improve spectral efficiency and provide massive connectivity in future wireless networks. However, the inherited security issues with NOMA should be carefully addressed to further exploit its potential benefits in NOMA enabled wireless networks. As such, we consider a cooperative NOMA network, where a source uses the NOMA to simultaneously communicate with a multi-antenna near-user and a far-user. While directly communicating with the near-user, the source employs multiple full-duplex (FD) decode-and forward (DF) relays to establish communication with the far-user in the presence of a passive eavesdropper. To address the eavesdropping in this cooperative NOMA network, we propose a new two-phase FD-based artificial noise (AN) scheme with different relay selection techniques. In the first phase, the selected FD relay emits AN to confuse the eavesdropper while receiving the superimposed signal from the source. In the second phase, the selected relay performs exclusive OR (XOR) operation on both the message intended to the far-user and the AN before broadcasting the resulting mixed signal. By utilizing null-space beamforming, self-interference cancellation techniques and DF-XOR cooperative protocol, the AN in the proposed scheme can be efficiently eliminated at the near-user and far-user as well as at the selected relay. However, the AN cannot be suppressed at the eavesdropper which serves the purpose of AN through degrading the decoding capability of the eavesdropper. We evaluate the performance of the proposed scheme in terms of security-reliability trade-off (SRT). For the AN-aided scheme with max-min and partial relay selection techniques, we theoretically derive the exact and asymptotic closed-form expressions of the outage probability and intercept probability. Numerical results have been provided to validate the derivations. In addition, the results reveal that the SRT of the near-user and far-user can be improved by increasing the number of antennas at the near-user and the number of relays.

DNN-Powered SIC-Free Receiver Artificial Noise Aided Terahertz Secure Communications With Randomly Distributed Eavesdroppers

Despite the narrowbeam nature of Terahertz (THz) communications, the physical layer security in the THz band is challenging when eavesdroppers are inside the beam radiation sector. In this paper, a deep neural network (DNN)-based self-interference cancellation (SIC)-free receiver artificial noise (AN) assisted mechanism is proposed to address the in-beam security challenge, by considering randomly distributed eavesdroppers in THz secure communications. By exploiting the different temporal broadening effects of the AN signals at distinct distances, the SIC can be saved with a proper signal detection design rather than using conventional high-complexity cancellation techniques. To combat the non-linearity and non-convexity of the optimization problem, the system parameters including carrier frequency, power of transmission signal and AN signal power, and frame time are designed by an efficient deep neural network (DNN) algorithm to minimize the secrecy outage probability. Numerical results demonstrate that the maximum secrecy rate of our proposed DNN-powered SIC-free receiver AN scheme is up to 3.3 bps/Hz over 10 m transmission when the eavesdropper is in close proximity. Moreover, the secrecy outage probability is less than 0.5% when the eavesdropper density is 0.001 per square meter, which is approximately 33% lower than that of conventional transmitter AN schemes.

Cooperative Beamforming and Jamming for Secure VLC System in the Presence of Active and Passive Eavesdroppers

This paper proposes a novel cooperative beamforming and jamming scheme to deal with passive and active eavesdroppers (EDs) in indoor visible light communication (VLC) networks. An ED in VLC systems can augment its front-end receiver by implementing possible device modifications; thus, jamming is very useful for curbing such an enhanced ED since it would be impossible to distinguish between the information and jamming signals. In contrast to the traditional artificial noise strategies for VLC that can only deal with either passive or active EDs, we propose a combined scheme of beamforming and jamming that significantly improves secrecy performance when both types of EDs exist. The proposed scheme is designed to maximize the signal-to-interference-plus-noise ratio (SINR) of the legitimate receiver, entirely suppress the SINRs of the active EDs, and restrict the average SINR of the passive EDs. We apply an inverse free preconditioned Krylov subspace projection method and the convex-concave procedure to obtain the suboptimal beamforming weight and jamming intensity vectors. Also, an optimal power splitter coefficient is found through the golden section search method. The numerical results verify that the proposed scheme shows superior performance compared to the three benchmarks: 1) zero-forcing beamforming; 2) artificial noise scheme; and 3) enhanced zero-forcing beamforming.

Security-Reliability Trade-Off Analysis of AN-Aided Relay Selection for Full-Duplex Relay Networks

This paper proposes a new artificial noise (AN) scheme that combines with the relay selection techniques to improve the physical layer security for a wiretap full-duplex decode-and-forward cooperative network. The communication consists of two phases. In the first phase, the source transmits a message to the selected full-duplex relay, which simultaneously injects AN to mitigate eavesdropping attacks. In the second phase, the selected relay decodes the source message, XORs the source message and AN, and then broadcasts the mixed-signal to the destination. Different form existing schemes, the proposed AN scheme makes the eavesdropper fail in obtaining any information about the source message directly in the second phase. We take into account the correlation of the channel coefficients for the same link during different phases in the performance analysis of AN-aided max-min (MM) and partial (Par) relay selection schemes, and characterize the security-reliability trade-off (SRT) of the proposed schemes by the closed-form expressions of outage probability and intercept probability. Numerical results show that the proposed AN-aided MM/Par relay selection achieves a better SRT performance than the corresponding full-duplex mode assisted AN-aided relay selection scheme in existing literature. Furthermore, the MM scheme outperforms the Par scheme in terms of the SRT, and the SRT of the MM scheme can be substantially improved by increasing the number of relays, while the improvement of the Par scheme is limited.

Physical Layer Security Assisted Computation Offloading in Intelligently Connected Vehicle Networks

In this paper, we propose a secure computationoffloading scheme (SCOS) in intelligently connected vehicle (ICV) networks, aiming to minimize overall latency of computing via offloading part of computational tasks to nearby servers in small cell base stations (SBSs), while securing the information delivered during offloading and feedback phases via physical layer security. Existing computation offloading schemes usually neglected time-varying characteristics of channels and their corresponding secrecy rates, resulting in an inappropriate task partition ratio and a large secrecy outage probability. To address these issues, we utilize an ergodic secrecy rate to determine how many tasks are offloaded to the edge, where ergodic secrecy rate represents the average secrecy rate over all realizations in a time-varying wireless channel. Adaptive wiretap code rates are proposed with a secrecy outage constraint to match time-varying wireless channels. In addition, the proposed secure beamforming and artificial noise (AN) schemes can improve the ergodic secrecy rates of uplink and downlink channels even without eavesdropper channel state information (CSI). Numerical results demonstrate that the proposed schemes have a shorter system delay than the strategies neglecting time-varying characteristics.

Achieving Reliable and Secure Communications in Wireless-Powered NOMA Systems

This article studies the reliable and secure communications for a wireless-powered non-orthogonal multiple access (NOMA) system in the presence of multiple eavesdroppers. A joint artificial noise and power allocation (JAP) scheme is proposed to ensure the reliability and security for the system. Based on the JAP scheme, analytical closed-form expressions for connection outage probability (COP), secrecy outage probability (SOP) and effective secrecy throughput (EST) are derived, respectively, to evaluate the performance of the security-required user. Also, the asymptotic SOP and EST are analyzed to gain further insights. The numerical results demonstrate the correctness of the theoretic analysis and indicate that the proposed JAP scheme can achieve a better performance than the benchmark schemes.

Hardware Impaired Ambient Backscatter NOMA Systems: Reliability and Security

Non-orthogonal multiple access (NOMA) and ambient backscatter communication have been envisioned as two promising technologies for the Internet-of-things due to their high spectral efficiency and energy efficiency. Motivated by this fact, we consider an ambient backscatter NOMA system in the presence of a malicious eavesdropper. Under the realistic assumptions of residual hardware impairments (RHIs), channel estimation errors (CEEs) and imperfect successive interference cancellation (ipSIC), we investigate the physical layer security (PLS) of the ambient backscatter NOMA systems with emphasis on reliability and security. In order to further improve the security of the considered system, an artificial noise scheme is proposed where the radio frequency (RF) source acts as a jammer that transmits interference signals to the legitimate receivers and eavesdropper. On this basis, the analytical expressions for the outage probability (OP) and the intercept probability (IP) are derived. To gain more insights, the asymptotic analysis and corresponding diversity orders for the OP in the high signal-to-noise ratio (SNR) regime are carried out, and the asymptotic behaviors of the IP in the high main-to-eavesdropper ratio (MER) region are explored as well. Finally, the correctness of the theoretical analysis is verified by the Monte Carlo simulation results. These results show that compared with the non-ideal conditions, the reliability of the considered system is high under ideal conditions, but the security is low.

Secure Content Delivery in Two-Tier Cache-Enabled mmWave Heterogeneous Networks

In this paper, we investigate secure content delivery in a two-tier cache-enabled millimeter wave (mmWave) heterogeneous network composed of a macro base station (MBS) and K small base stations (SBSs) with caching capabilities. We allocate finite cache units at the SBSs and MBS to pre-store files with high popularities, where the SBSs store the most popular files, and the MBS stores the less popular ones. To deliver the file requested by a legitimate user securely, two secure transmission schemes, namely, distributed beamforming and direct transmission, are employed at the SBSs and MBS, respectively. Moreover, artificial noise (AN) is combined with the above two transmission schemes to further improve transmission security. The connection outage probability, secrecy outage probability, and secrecy throughput for the proposed mmWave transmission schemes are obtained. Based on these results, we jointly design the transmission rates and the cache resource allocation between the SBSs and MBS to maximize the overall secrecy throughput. We also provide insights into how the overall secrecy throughput is influenced by various parameters, including transmission rates, power allocation ratio of the AN scheme, and cache allocation factor. Numerical results are eventually presented to validate our theoretical analysis and demonstrate the effectiveness of the proposed transmission schemes and cache resource allocation strategy.

Performance Analysis and Optimization of Secure Generalized Spatial Modulation

Artificial noise (AN) is considered as a new physical layer technology to improve the security of wireless systems. In this paper, we investigate secure transmission of AN-aided generalized spatial modulation (GSM), which maintains the same hardware requirements at the transmitter as the conventional GSM. In order to further improve the jamming intensity of conventional AN scheme, we propose an Euclidean distance optimized AN (ED-AN) scheme by minimizing the Euclidean distance between the transmit signal and the jamming signal, which also avoids the power waste of conventional AN scheme. The secrecy capacities of both the AN-GSM and EDAN-GSM schemes are analyzed, and the optimal power allocation of AN-GSM is further investigated by maximizing the secrecy capacity. Furthermore, the upper bounds of the theoretical bit error rates (BERs) of both the legitimate receiver and the illegal eavesdropper over the Rayleigh fading channel are derived. Simulation results validate our derived analysis and demonstrate that the ED-AN scheme offers better secrecy and BER performance.

Deep Artificial Noise: Deep Learning-Based Precoding Optimization for Artificial Noise Scheme

In this work, we consider a secure precoding optimization problem for the artificial noise (AN) scheme in multiple-input single-output (MISO) wiretap channels. In previous researches (Lin et al., 2013), it was proved that the generalized AN scheme which allows some portion of AN signal to be injected to the legitimate receiver's channel is the optimal precoding scheme for MISO wiretap channels. However, the optimality is valid only under some ideal assumptions such as perfect channel estimation and spatially uncorrelated channels. To break through this limitation, in this paper, we propose a novel deep neural network (DNN)-based secure precoding scheme, called the deep AN scheme. To the best of the authors' knowledge, the deep AN scheme is the first secure precoding scheme which exploits a DNN to jointly design and optimize the precoders for the information signal and the AN signal. From the numerical experiments, it is demonstrated that the proposed deep AN scheme outperforms the generalized AN scheme under various practical wireless environments.

Ergodic Secrecy Rate of $K$-User MISO Broadcast Channel With Improved Random Beamforming

In this paper, we study the secrecy performance of a $K$ -user multi-input single-output (MISO) broadcast channel with random beamforming (RB), where the transmitter is equipped with $N$ antennas, and the eavesdropper has $N_e$ antennas. We first propose a signal-splitting random beamforming (SSRB) scheme for a single-user MISO wiretap channel, and then improve the SSRB scheme with power-minimizing (PM), which is called a PM-SSRB scheme. To improve the spectral efficiency of a multiuser network, we combine PM with non-orthogonal multiple access (NOMA), and propose a hybrid NOMA (H-NOMA) scheme and a signal-splitting NOMA (SS-NOMA) scheme for the $K$ -user MISO wiretap channel, respectively. The sum ergodic secrecy rate of the $K$ -user scenario is analyzed comprehensively, and a closed-form expression for the lower bound on the ergodic secrecy rate is also derived for the single-user case. Simulation results show that, compared with the traditional hybrid artificial fast-fading scheme (AFF) and artificial noise (AN) scheme, the proposed SSRB scheme and PM-SSRB scheme perform much better in terms of the ergodic secrecy rate in all power regimes. More importantly, when the eavesdropper has more antennas than the transmitter, our schemes always outperform the AFF and AN schemes. The PM-SSRB scheme is also shown to be superior to the secret-key AFF scheme. For the multiuser case, the SS-NOMA scheme can achieve higher ergodic secrecy rate than the H-NOMA scheme.

Downlink Secrecy Rate of One-Bit Massive MIMO System With Active Eavesdropping

In this study, we consider the physical layer security in the downlink of a Massive MIMO system employing one-bit quantization at the base station (BS). We assume an active eavesdropper that attempts to spoiling the channel estimation acquisition at the BS for a legitimate user, whereas overhearing on downlink transmission. We consider the two most widespread methods for degrading the eavesdropper's channel, the nullspace artificial noise (NS-AN) and random artificial noise (R-AN). Then, we present a lower bound on the secrecy rate and asymptotic performance, considering zero-forcing beamforming (ZF-BF) and maximum-ratio transmission beamforming (MRT-BF). Our results reveal that even when the eavesdropper is close enough to the intercepted user, a positive secrecy rate --which tends to saturation with increasing the number of BS antennas $N$---is possible, as long as the transmit power of eavesdropper is less than that of the legitimate user during channel training. We show that ZF-BF with NS-AN provides the best performance. It is found that MRT-BF and ZF-BF are equivalent in the asymptotic limit of $N$ and hence the artificial noise technique is the performance indicator. Moreover, we study the impact of \emph{power-scaling law} on the secrecy rate. When the transmit power of BS is reduced proportional to $1/N$, the performance is independent of artificial noise asymptotically and hence the beamforming technique is the performance indicator. In addition, when the BS's power is reduced proportional to $1/\sqrt{N}$, all combinations of beamforming and artificial noise schemes are equally likely asymptotically, independent of quantization noise. We present various numerical results to corroborate our analysis.

Artificial Noise Scheme for Correlated MISO Wiretap Channels

This correspondence paper studies how correlation of the wiretap channel affects the secrecy rate of the artificial noise (AN) scheme. To this end, we first develop a simple but tight lower bound on the ergodic secrecy rate of the AN scheme on correlated multiple-input single-output wiretap channels. Then, utilizing the derived bound, we investigate the influence of correlation on the secrecy rate, which explicitly manifests how the channel correlation affects the optimal power allocation. Ultimately, this paper answers two fundamental questions: when is the AN signal beneficial? and how much power should be allocated for the AN signal to achieve a higher ergodic secrecy rate? in terms of channel correlation.

Artificial Noisy MIMO Systems Under Correlated Scattering Rayleigh Fading—A Physical Layer Security Approach

The existing investigations on artificial noise (AN) security systems assumed that only null spaces is used to send AN signals, and all eigen-subchannels should be used to transmit messages. Our previous work proposed an AN scheme that allocates some of eigen-subchannels to transmit AN signals for improving secrecy rates. Nevertheless, our previous work considered only uncorrelated MIMO Rayleigh fading channels. In fact, the correlations among antennas exist in realistic scattering channel environments. In this paper, we extend our previous AN scheme to spatially correlated Rayleigh fading channels at both legitimate receiver- and eavesdropper-sides and derive an exact theoretical expression for the ergodic secrecy rate of the AN scheme, along with an approximate analysis. Both numerical and simulation results show that the proposed AN scheme offers a higher ergodic secrecy rate than the existing schemes, revealing a fact that the correlation among eavesdropper's antennas can potentially improve the secrecy rate of an MIMO system.