Massive Multiple Input Multiple Output (MIMO) has been considered as an emerging technology to enhance the spectral and energy efficiency for the upcoming wireless communication systems. This paper derives a closed-form approximation for the Ergodic Achievable Secrecy Sum-Rate (EASSR) by considering the joint impact of eavesdroppers and jammers. Two widely used linear precoding techniques, Zero-Forcing (ZF) and Maximum Ratio Transmission (MRT), were used in conjunction with matrix and vector normalization to analyze the secrecy performance. Closed-form expressions are used to explain how the secrecy performance is affected when using the ZF and MRT precoding in the eavesdropping and jamming attack models. We also analyze and compare the performances of different combinations of normalization method and precoding technique in various scenarios. From the analytical expressions and simulation results, we observe that the vector and matrix normalization perform better for the ZF precoding than for the MRT precoding in high Signal-to-Noise Ratio (SNR) scenarios. However, in low SNR, the MRT with matrix normalization outperforms the ZF with vector normalization regardless of the number of users in the system. Further, we observe that the MRT fails to serve more than two users in high SNR scenario. Numerical results obtained from Monte Carlo simulation are used to corroborate the accuracy of the asymptotic secrecy analysis.
Massive Multiple Input Multiple Output (MIMO) has been considered as an emerging technology to enhance the spectral and energy efficiency for the upcoming wireless communication systems. This paper derives a closed-form approximation for the Ergodic Achievable Secrecy Sum-Rate (EASSR) by considering the joint impact of eavesdroppers and jammers. Two widely used linear precoding techniques, Zero-Forcing (ZF) and Maximum Ratio Transmission (MRT), were used in conjunction with matrix and vector normalization to analyze the secrecy performance. Closed-form expressions are used to explain how the secrecy performance is affected when using the ZF and MRT precoding in the eavesdropping and jamming attack models. We also analyze and compare the performances of different combinations of normalization method and precoding technique in various scenarios. From the analytical expressions and simulation results, we observe that the vector and matrix normalization perform better for the ZF precoding than for the MRT precoding in high Signal-to-Noise Ratio (SNR) scenarios. However, in low SNR, the MRT with matrix normalization outperforms the ZF with vector normalization regardless of the number of users in the system. Further, we observe that the MRT fails to serve more than two users in high SNR scenario. Numerical results obtained from Monte Carlo simulation are used to corroborate the accuracy of the asymptotic secrecy analysis.
In this paper, we investigate the secrecy performance of matched-filter (MF) and zero-forcing (ZF) precoding in a multiuser massive multiple-input multiple-output (MIMO) system with a multi-antenna passive eavesdropper. For the two precoding schemes, we find that the equivalent wiretap channels are similar and thus the eavesdropper achieves the approximate same sum-rate. Closed-form expressions of ergodic secrecy sum-rate (ESSR) are derived for the both schemes in the low and high signal-to-noise ratio (SNR) regimes. We show that a positive ESSR of MF scheme may be not achieved when the BS simultaneously serves more than two users with high transmit power, while the ESSR of ZF scheme always grows with the number of the served users. On the contrast, MF scheme is better than ZF scheme in the low SNR regime. Simulation results corroborate the analytic results.
In this paper, we investigate the secrecy performance of matched-filter (MF) and zero-forcing (ZF) precoding in a multiuser massive multiple-input multiple-output (MIMO) system with a multi-antenna passive eavesdropper. For the two precoding schemes, we find that the equivalent wiretap channels are similar and thus the eavesdropper achieves the approximate same sum-rate. Closed-form expressions of ergodic secrecy sum-rate (ESSR) are derived for the both schemes in the low and high signal-to-noise ratio (SNR) regimes. We show that a positive ESSR of MF scheme may be not achieved when the BS simultaneously serves more than two users with high transmit power, while the ESSR of ZF scheme always grows with the number of the served users. On the contrast, MF scheme is better than ZF scheme in the low SNR regime. Simulation results corroborate the analytic results.
Massive Multiple-Input Multiple-Output (MIMO) has become a crucial enabling technology for 5G and beyond, providing previously unheard-of increases in energy and spectrum efficiency. It is still difficult to guarantee secure communication in these systems, particularly when it comes to passive eavesdroppers whose base station is unaware of their channel state information. By taking advantage of the inherent randomness of wireless channels, Physical Layer Security (PLS) offers a promising paradigm; however, its efficacy in massive MIMO is heavily reliant on resource allocation and transmission strategies. In this work, the performance of secure transmission schemes, such as Maximum Ratio Transmission (MRT), Zero-Forcing (ZF), and Artificial Noise (AN)-aided beamforming, is examined when passive eavesdroppers are present. This work will use extensive Monte Carlo simulations to assess important performance metrics such as energy efficiency, secrecy outage probability, and secrecy sum rate under different system parameters (e.g., number of antennas, Signal-to-Noise Ratio (SNR), power allocation). The results aim to provide comparative insight into the strengths and limitations of different PLS strategies and to highlight open research directions to design scalable, energy-efficient, and robust secure transmission techniques in future 6G networks.
The secrecy performance of forward link multi-user massive multiple-input multiple-output (MIMO) system is investigated in this paper. The base station (BS) equipped with a large number of transmit antennas sends mutually independent datas to multiple single-antenna legitimate users simultaneously. A passive multi-antenna eavesdropper is placed in the scenario to intercept the signals. We consider the case that the number of legitimate users and eavesdropper antennas increases proportionally with the number of BS antennas. Maximum ratio transmission (MRT) is used as linear precoder at the BS. Lower bounds on the ergodic achievable rate of legitimate users and upper bounds of the eavesdropper are derived. By minimizing the upper bounds on the achievable rates of the eavesdropper while satisfying the rate constraints of legitimate users, we present the corresponding optimal radiated power scaling (RPS) factor. In the limit of an infinite number of BS antennas, we prove that the optimal RPS factor converge to a different constant limit with that of the case in which the number of legitimate users and eavesdropper antennas is finite. We show that when the number of BS antennas grows large, the secrecy performance is mainly determined by the ratios between the number of BS antennas, legitimate users and eavesdropper antennas. A number of simulation results are presented to visualize the analysis.
Transmit beamforming is a diversity technique in multiple-input multiple-output (MIMO) systems. It improves the diversity order and enhances the information security of the MIMO systems. In this paper, we mathematically analyze the secure performance of a MIMO decode-and-forward (DF) relay system under the presence of an eavesdropper and with the imperfect channel state information (CSI) of the eavesdropping channel. To enhance the secrecy performance, we employ multiple antennas at all legitimate nodes and utilize two linear beamforming schemes, i.e., maximal ratio transmission (MRT) and transmission zero-forcing (TZF), at the transmitter and maximal ratio combining (MRC) scheme at the receiver. The probability density function (PDF) of the output SNR for different numbers of antennas at the transmitter and receiver is plotted and discussed. After that, we apply this PDF to derive the closed-form expressions of the secrecy outage probability (SOP) and ergodic secrecy capacity (ESC) of the considered MIMO-DF relay system over Rayleigh fading channels for MRT/MRC and TZF/MRC schemes. In addition, based on the obtained analysis results, we provide the location of the relay that minimizes the system SOPs. All the analysis results are validated by Monte-Carlo simulations. The results show that the TZF/MRC scheme provides better SOP and ESC than the MRT/MRC scheme. Moreover, the number of antennas at the legitimate nodes and the location of the eavesdropper significantly impact the secrecy performance.
In massive multiple-input multiple-output (MIMO) systems, idle users may passively overhear the signal transmitted to the intended user, known as internal eavesdroppers. In order to improve the secrecy performance, artificial noise (AN) is used jointly with maximum ratio transmission (MRT) precoding. Since the idle users can be anywhere in the cell, we investigate the secrecy outage probability for the legitimate user by taking an expectation over the positions of all internal eavesdroppers. Furthermore, according to the secrecy performance of the legitimate user in the given location, we define a new concept Secrecy Area centered on the base station (BS) where all the legitimate users satisfy the secrecy quality-of-service (QoS) requirements i.e. secrecy outage probability. Then, in order to achieve the maximum Secrecy Area under the given secrecy QoS requirements, we derive the optimal power allocation factor for AN, which is irrelevant to the channel state information (CSI) of both the legitimate user and the eavesdropper. The analytical and simulation results show that, by AN-assisted MRT precoding, the secrecy performance is significantly improved and the Secrecy Area can be efficiently enlarged with a modest increase of the transmit power.