This paper investigates the physical layer security in wireless communication networks, focusing on the scenario where a base station sends confidential messages to a legitimate node while facing potential eavesdropping. The study assumes that the channel state information for both authorized and unauthorized nodes is not available. To assess both security and reliability, the paper introduces the use of bit error rate (BER) as a quantifiable security metric. The objective of the research is to evaluate the security performance improvement of the system through BER. Specifically, the impact of artificial noise (AN) power allocation ratio, and the number of transceiver antennas on BER performance is characterized. The numerical results demonstrate that artificial noise is effective against unknown passive eavesdropping attacks and leads to significant performance gains. For instance, by transmitting artificial noise power at approximately 50% of the total power to deliberately impair the eavesdropper’s reception, the BER gap between intended and unauthorized users can reach 0.4.
This paper investigates the physical layer security in wireless communication networks, focusing on the scenario where a base station sends confidential messages to a legitimate node while facing potential eavesdropping. The study assumes that the channel state information for both authorized and unauthorized nodes is not available. To assess both security and reliability, the paper introduces the use of bit error rate (BER) as a quantifiable security metric. The objective of the research is to evaluate the security performance improvement of the system through BER. Specifically, the impact of artificial noise (AN) power allocation ratio, and the number of transceiver antennas on BER performance is characterized. The numerical results demonstrate that artificial noise is effective against unknown passive eavesdropping attacks and leads to significant performance gains. For instance, by transmitting artificial noise power at approximately 50% of the total power to deliberately impair the eavesdropper’s reception, the BER gap between intended and unauthorized users can reach 0.4.
In this paper, we address the issue of incorporating physical layer security (PLS). This scenario involves a base station transmitting confidential messages to a legitimate node, all while contending with the presence of a potential eavesdropper. Our assumption is that we lack access to the channel state information pertaining to both the authorized and unauthorized nodes. Moreover, bit error rate (BER) is introduced as an easily quantifiable security metric, which can assess not only the system’s security but also its reliability. The goal of this paper is to evaluate the system’s security performance gain through the BER. Specifically, we characterize the impact of the allocation ratio of artificial noise (AN) power, the number of transceiver antennas and the communication distance on the BER performance. Numerical results reveal that the AN is robust against the unknown passive eavesdropping attack and achieves significant performance gains. For example, the BER gap between intended and illegal users can reach 0.4 by transmitting AN power at approximately 50% of the total power to deliberately impair the eavesdropper’s reception.
Physical layer security (PLS) has grown in popularity as it guarantees secure and reliable communication between wireless devices without restricting the ability of data analysts to eavesdrop. PLS benefits from the randomization property of the wireless channel, which improves immunity and protects against many dangers of information breaches from eavesdroppers. MIMO and Massive MIMO, which use numerous antennas at the transmitter and receiver ends, are fundamental technologies for improving efficiency in 5G and future network systems. The PLS still requires a significant amount of work before it can be employed in practical systems. The interception of eavesdroppers can be made difficult by adding artificial noise. This paper focuses on the physical layer security considering maximal ratio combining, and artificial noise with beamforming techniques to further enhance the secrecy rate. The proposed work demonstrates that the use of transmitter beamforming with artificial noise can significantly improve the degree of confidentiality of information being transmitted between a transmitter and an intended receiver while making it more difficult for eavesdroppers to intercept. The simulation results in terms of bit error rate show that the proposed method has a significant impact on the error rate performance of the eavesdropper.
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.
Security is one of the major issues in wireless communication system. In a wireless communication system as the transmission of information signal is over the air, eavesdroppers may have easy access to the transmitted data. The conventional network security mainly depends on cryptographic schemes. But as the security level increases, computational complexity will be high and cause complex key management problems. In this paper, the problem of secret communication between two nodes in the presence of a passive eavesdropper is considered. In general, nodes with multiple transmit antenna elements can ensure secure communication using directional antenna. In this paper, MIMO channel with multiple transmit antenna elements utilize fraction of the available power to produce „artificial noise‟ for the improvement of secure communication. The artificial noise is generated by the transmitter in such away that it degrades only the eavesdropper‟s channel. The various performance metrics such as bit error rate, channel capacity, optimal power allocation and secrecy rate were analyzed in the presence of non-colluding and colluding eavesdroppers. The obtained simulation results are compared with the existing work that does not use artificial noise. It is inferred from the results that the proposed work achieves improved secrecy rate than the existing work.
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 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/√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.
In this thesis, we study the physical layer security in downlink multi-user wireless networks. Traditionally, security has been addressed by cryptography at the higher layers of the communication stack. Security at the physical layer has been a major research topic in recent years. We study two different precoder designs alongside artificial noise (AN) to mitigate multi-user interference and deteriorate reception at the eavesdropper (Eve). We study the large scale analysis to calculate the secrecy sum-rate for these two cases and analyze the effect of AN on the system. First, we consider the worst case scenario, when eavesdropper's (Eve's) rate is not deteriorated by the interference caused by the legitimate users. Later, we investigate how interference from legitimate users would affect the large scale security sum rate. At the end, we assume more practical situation where the channel state information at the transmitter is not perfect due to feedback limitation and estimation error. We first study block diagonalization (BD) precoding. We derive the asymptotic secrecy sum-rate of BD for physical layer security in downlink multi-user wireless networks using artificial noise (AN). We first derive the secrecy sum-rate assuming that the channel of the eavesdropper is not known at the transmitter and derive the asymptotic secrecy sum-rate. Then we derive the optimum power allocation for asymptotic secrecy sum-rate. We design the system based on large scale analysis for different special cases. Simulation results show that the proposed precoders outperform channel inversion (CI) and regularized channel inversion (RCI) schemes at all SNRs. We also show that as the number of receive antennas of each user increases, the sum-rate gap between the proposed scheme and existing methods increases. We, then, study two methods of regularized block diagonalization (RBD) precoding using artificial noise (AN) for physical layer security in downlink multi-user MIMO wireless networks. We compare the complexity analysis of these two methods in terms of floating point operations per second (FLOPS). We derive the secrecy and asymptotic secrecy sum-rates for these schemes. We also derive closed form expressions for the asymptotic optimal power allocation to the AN signal and legitimate users. Simulations show RBD precoding outperform regularized channel inversion (RCI) in terms of secrecy sum-rate with a margin of 0.5 bits/s/Hz. Also, simulation results show our closed-form asymptotic secrecy sum-rates matches closely with the simulations for perfect and imperfect CSIT. We also study the effect of interference on BD precoding scheme. In the first two studies the worst case scenarios was considered and the effect of interference was not considered at the eavesdropper. We first derive the closed-form secrecy and asymptotic secrecy sum-rates for this scheme. Then, we derive the optimum power allocation. Using the derived optimum power allocation, we determine the conditions under which adding AN helps. We also investigate the optimum number of users, number of antennas at the eavesdropper, and the number of transmit antennas to fully study the conditions where using AN improves performance. We show that as the number of users increases or the number of receive antennas at the eavesdropper decreases, improved performance is achieved by allocating a smaller fraction of the total power to transmit the AN. The closed form expressions for the secrecy sum rate (SSR) and optimum power allocation closely match our simulation results. In Chapter 5, we study the effect of imperfect channel state information at the transmitter (CSIT) for each case studied in earlier chapters. We first study the effect of imperfect CSIT for BD precoding in both scenarios when interference does and does not exist at eavesdropper. We show that the imperfect CSI play the same role as interference for the desired users. Then, we study the effect of imperfect CSIT for RBD precoding when interference does not exist at eavesdropper. We show as channel estimation error increases, the secrecy sum-rate decreases. This is due to the fact that channel estimation error just affects the desired users' rate and has no effect on eavesdropper's performance. Finally, in the last chapter, we conclude our thesis and provide some road map for future--Author's abstract