Physical Layer Security (PLS) in Multiple Input Multiple Output (MIMO) systems is crucial to achieving reliable communication. Artificial Noise (AN) is a commonly employed technique to provide PLS-based secure communication. This requires perfect knowledge of the channel between transmitter (Alice) and legitimate user (Bob). However, this channel information may be imperfect due to estimation errors. Thus, the claimed performance of AN-based PLS is questionable and requires thorough investigation. In this work, the effect of imperfect channel estimation on the performance of PLS for multiuser Massive (MU-Massive) MIMO system is investigated. The channel estimation error is modeled as a complex Gaussian variable. The performance measure in terms of Bit-error-rate (BER) is evaluated for different levels of channel estimation error. This investigation provides a good illustration of how the performance of AN-based PLS is affected by the channel estimation error in the MU-Massive MIMO system. This work shows the trend in BER increase with the increase in AN mismatch.
Physical Layer Security (PLS) in Multiple Input Multiple Output (MIMO) systems is crucial to achieving reliable communication. Artificial Noise (AN) is a commonly employed technique to provide PLS-based secure communication. This requires perfect knowledge of the channel between transmitter (Alice) and legitimate user (Bob). However, this channel information may be imperfect due to estimation errors. Thus, the claimed performance of AN-based PLS is questionable and requires thorough investigation. In this work, the effect of imperfect channel estimation on the performance of PLS for multiuser Massive (MU-Massive) MIMO system is investigated. The channel estimation error is modeled as a complex Gaussian variable. The performance measure in terms of Bit-error-rate (BER) is evaluated for different levels of channel estimation error. This investigation provides a good illustration of how the performance of AN-based PLS is affected by the channel estimation error in the MU-Massive MIMO system. This work shows the trend in BER increase with the increase in AN mismatch.
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.
In this paper, a secure communication model for cognitive multi-user massive multiple-input multiple-output (MIMO) systems with underlay spectrum sharing is investigated. A secondary (cognitive) multi-user massive MIMO system is operated by using underlay spectrum sharing within a primary (licensed) multi-user massive MIMO system. A passive multi-antenna eavesdropper is assumed to be eavesdropping upon either the primary or secondary confidential transmissions. To this end, a physical layer security strategy is provisioned for the primary and secondary transmissions via artificial noise (AN) generation at the primary base-station (PBS) and zero-forcing precoders. Specifically, the precoders are constructed by using the channel estimates with pilot contamination. In order to degrade the interception of confidential transmissions at the eavesdropper, the AN sequences are transmitted at the PBS by exploiting the excess degrees-of-freedom offered by its massive antenna array and by using random AN shaping matrices. The channel estimates at the PBS and secondary base-station (SBS) are obtained by using non-orthogonal pilot sequences transmitted by the primary user nodes (PUs) and secondary user nodes (SUs), respectively. Hence, these channel estimates are affected by intra-cell pilot contamination. In this context, the detrimental effects of intra-cell pilot contamination and channel estimation errors for physical layer secure communication are investigated. For this system set-up, the average and asymptotic achievable secrecy rate expressions are derived in closed-form. Specifically, these performance metrics are studied for imperfect channel state information (CSI) and for perfect CSI, and thereby, the secrecy rate degradation due to inaccurate channel knowledge and intra-cell pilot contamination is quantified. Our analysis reveals that a physical layer secure communication can be provisioned for both primary and secondary massive MIMO systems even with the channel estimation errors and pilot contamination.
In recent years, physical layer security (PLS) has emerged as a promising concept to complement cryptography solutions. Many PLS schemes require perfect knowledge of the channel state information (CSI) at the transmitter. However, in practical cases, CSI is often imperfect due to channel estimation errors, noisy feedback channels and outdated CSI. In this paper, we study the impact of imperfect CSI on an adaptive PLS scheme that combines diversity with interleaving to provide security. Particularly, we derive the secrecy capacity expressions for the legitimate receiver and the eavesdropper's channels under imperfect CSI conditions. Numerical and theoretical simulations for secrecy capacity and bit error rate (BER) are carried out for the frequency-selective Rayleigh fading wiretap channel model. The results reveal the negative impact of imperfect CSI on the secrecy and BER performance of the single input single output (SISO) orthogonal frequency division multiplexing (OFDM) system. The analysis is done under both frequency division duplex (FDD) and time division duplex (TDD) modes.
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.
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.
In this paper, we investigate a multiuser MIMO downlink with imperfect channel state information (CSI) from the physical-layer security provision. In a classical transmitter (Alice)-legitimate receiver (Bob)-eavesdropper (Eve) model using artificial noise to disturb Eve's reception, we consider a general scenario where all nodes are equipped with multiple antennas, and Bob's CSI is acquired by pilot-assisted channel estimation. For designing the secure transmit beamforming, we utilize random matrix quantization (RMQ) to quantize Bob's channel estimate, and then Bob feeds it back to Alice. Due to the effects of imperfect CSI at Alice, the secrecy performance is upper bounded in the high signal-to-noise ratio (SNR) regions. In order to avoid the interference-limited phenomenon, we present a scaled strategy for the secrecy system utilizing derived upper bound on the secrecy rate loss. Moreover, it is shown that our derived results can be easily extended to a special case where both legitimate and eavesdropping receivers equip a single antenna each, where random vector quantization (RVQ) is utilized instead. By employing our proposed feedback strategy, the secrecy rate increases with transmit power, and the certain secrecy requirement can be guaranteed.