In this paper, the physical layer security (PLS) issue is studied for frequency-division duplex (FDD) multiple-input multiple-output (MIMO) media-based modulation (MBM) systems with a multiple-antenna eavesdropper. A more practical scenario is considered that only the statistic channel state information (CSI) of the eavesdropping link is available and the imperfect CSI of the legitimate link is acquired by analog feedback. Based on these imperfect CSI, an artificial-noised-aided precoding scheme is proposed, and an effective achievable ergodic secrecy rate (ESR) is derived when taking into account the feedback overhead. The secrecy performance of the proposed scheme is evaluated through simulations in terms of ESR and bit error rate (BER). The influences of the key parameters such as the power allocation ratio and the feedback duration are also discussed.
In this paper, the physical layer security (PLS) issue is studied for frequency-division duplex (FDD) multiple-input multiple-output (MIMO) media-based modulation (MBM) systems with a multiple-antenna eavesdropper. A more practical scenario is considered that only the statistic channel state information (CSI) of the eavesdropping link is available and the imperfect CSI of the legitimate link is acquired by analog feedback. Based on these imperfect CSI, an artificial-noised-aided precoding scheme is proposed, and an effective achievable ergodic secrecy rate (ESR) is derived when taking into account the feedback overhead. The secrecy performance of the proposed scheme is evaluated through simulations in terms of ESR and bit error rate (BER). The influences of the key parameters such as the power allocation ratio and the feedback duration are also discussed.
This paper proposes a framework for the artificial noise assisted secure transmission in multiple-input, multiple-output, multiple antenna eavesdropper (MIMOME) wiretap channels in frequency-division duplexed (FDD) systems. We focus on a practical scenario that only the eavesdroppers' channel distribution information (CDI) is available and the imperfect channel state information (CSI) of the legitimate receiver is acquired through training and analog feedback. By taking explicitly into account the signaling overhead and training power overhead incurred by channel estimation and feedback, we define the achievable effective ergodic secrecy rate (ESR), and investigate a joint power allocation and training overhead optimization problem for the maximization of effective ESR. We first derive a deterministic approximation for the achievable effective ESR which facilitates the joint optimization. Then, efficient iterative algorithms are proposed to solve the considered nonconvex optimization problem. In particular, in the high-SNR regime, a block coordinate descent method (BCDM) is proposed to handle the joint optimization. In the low-SNR regime, we transform the problem into a sequence of geometric programmings (GPs) and locate its Karush-Kuhn-Tucker (KKT) solution using the successive convex approximation (SCA) method. For the general case of SNR, we maximize the lower bound of the achievable effective ESR. Simulation results corroborate the theoretical analysis and illustrate the secrecy performance of the proposed secure transmission scheme.
Media-based modulation (MBM) has become a promising technology for wireless communications, which offers significant throughput enhancement and superior performance due to the channel diversity gain achieved by RF mirrors. In this paper, the physical-layer security (PLS) issue is investigated for the single-input-multiple-output MBM (SIMO-MBM) system, and a secure SIMO-MBM system is proposed. Especially, by considering time-division duplexing (TDD) mode, based on its channel reciprocity property, both the data symbol bits and the index bits are protected from the eavesdropper by using the amplitude and phase information of the legitimate channel states as the secret key. For performance evaluation, the bit error rate (BER) of the eavesdropper as well as the system secrecy mutual information are investigated, and Monte Carlo simulations are carried out. Simulation results demonstrate that, the proposed secure SIMO-MBM system is capable of efficiently preventing data leakage whilst ensuring reliable data transmission.
In this paper, a physical layer security scheme is proposed for index modulation aided orthogonal time frequency space (IM-OTFS) modulation systems working in Frequency Division Duplex (FDD) mode. In FDD systems, the channel reciprocity, which is the basic assumption for most physical layer security (PLS) techniques, is not applicable. To deal with the security challenge in FDD IM-OTFS systems, Chaos sequence is generated by exploiting the angular reciprocity of the legitimate link to construct the secure mapping rule between the information bits and the modulation symbols as well as the symbol indices. A PLS scheme based on the proposed secure mapping is introduced. The secrecy performance of the proposed PLS scheme is analyzed in terms of Bit Error Rate (BER) and the ergodic secrecy rate. Furthermore, a close-form approximated ergodic secrecy rate is derived to reduce the computational complexity. A truncation method is proposed to obtain robust secure transmissions when the angles of the uplink and downlink legitimate channels are estimated with errors. Simulation results show that the theoretical BER curve approaches the simulated BER curve closely for medium and high signal to noise ratio (SNR) regions, and the eavesdropper’s BER is always around 0.5 for all SNRs. The closed-form approximated ergodic secrecy rate fits the ergodic secrecy rate exactly in low and high SNR regions, and can work as a lower bound of the ergodic secrecy rate in medium SNR region. The secure mapping at the legitimate users is not affected by the angle estimation errors by using the truncation method, while the eavesdropper’s BER is influenced and the influence is analyzed.
At present, there has been a large amount of research on secrecy rate optimization. However, the reliability analysis of secure transmission is equally important although relatively less attention has been dedicated to. Therefore, this paper proposes a secure transmission method with artificial noise for the physical layer security issues in the transmission process of Multiple Input Multiple Output (MIMO) wireless communication systems. Firstly, we establish an artificial noise assisted MIMO systems model. Then, the channel state information (CSI) matrix is subjected to singular value decomposition to obtain the reasonable precoding and artificial noise matrices. Finally, the impact of artificial noise on the bit error rate performance of potential eavesdropper is analyzed, and based on the analysis, the problem of maximizing the system secrecy rate is established. The concave-convex procedure (CCCP) method is used to obtain the optimal power allocation, which significantly improves the security of MIMO systems. The simulation results show that using the null space of CSI matrix and artificial noise for signal encryption effectively improves the bit error rate of potential eavesdropping nodes. In addition, the secrecy rate obtained by the CCCP algorithm is consistent with the performance obtained by the particle swarm optimization algorithm, which verifies the effectiveness of the proposed algorithm.
In this paper, a physical layer security (PLS) scheme based on quadrature channel modulation (QCM) called secure QCM (SQCM) is proposed for time division duplex (TDD) multi-input multi-output (MIMO) media based modulation (MBM) systems to resist eavesdropping. By exploiting the abundant legitimate channel realizations generated by the radio frequency (RF) mirrors, secure mappings between the original information bits and the transmit patterns are designed, where the transmit patterns include the transmit antenna activation pattern (AAP), mirror activation pattern (MAP) and symbol modulation pattern. The secure mappings used by the transmitter change for each transmission and are unavailable at the eavesdropper due to the independent fading of the legitimate link and the eavesdropping link. Based on the secure mappings, the proposed SQCM conveys the source information bits securely through the complex modulation symbol and instantaneous channel realizations by using a single RF chain. The ergodic secrecy rate is analyzed and a closed-form approximation is derived. Simulation results show that the closed-form approximation coincides with the experimental ergodic secrecy rate, and the achievable ergodic secrecy rate is not influenced by the number of eavesdropping antennas or the channel advantage of the eavesdropping link. Compared to the secure MBM scheme using the traditional artificial noise (AN) technique, the proposed SQCM scheme shows significant performance gain without consuming jamming power when the eavesdropper has more antennas than the legitimate receiver. Compared to the precoded MBM and probabilistic optimized MBM schemes exploiting the eavesdropper's CSI, the proposed SQCM scheme has better secrecy performance in all SNR region and medium-to-high SNR regions respectively without requiring the eavesdropper's CSI.
Physical layer security (PLS) is an emerging paradigm that makes use of wireless channel characteristics to provide security. Many PLS schemes require knowledge of the channel state information (CSI). However, CSI is usually imperfect due to factors such as noisy feedback channels, channel estimation errors and outdated CSI. In this paper, we investigate the impact of imperfect CSI on the secrecy and error rate performances of a PLS scheme that combines adaptive matched-filter (MF) precoding and diversity in orthogonal frequency division multiplexing (OFDM). Particularly, we derive the secrecy capacity and error rate expressions for the legitimate and eavesdropper's channels under imperfect CSI assumption. The impact of the imperfect CSI is studied via theoretical as well as numerical techniques in frequency-selective Rayleigh fading wiretap channel. The analysis is done in both frequency division duplex (FDD) and time division duplex (TDD) modes.