In multiple-input–multiple-output (MIMO) wireless communications, spatial modulation (SM) has recently emerged as a new transmission method. This letter explores the physical-layer security in typical SM systems. We present a secrecy rate analysis for multiple antenna destination and eavesdroppers receivers. Targeting against passive eavesdroppers in unknown locations, we study the efficacy of active security measure through joint signal and jamming transmission without the typical requirement of eavesdropper channel information. We demonstrate the secrecy rate and transmission power tradeoff in active source jamming by providing numerical results on achieved secrecy rate and the bit error rate (BER) at different receivers.
In multiple-input–multiple-output (MIMO) wireless communications, spatial modulation (SM) has recently emerged as a new transmission method. This letter explores the physical-layer security in typical SM systems. We present a secrecy rate analysis for multiple antenna destination and eavesdroppers receivers. Targeting against passive eavesdroppers in unknown locations, we study the efficacy of active security measure through joint signal and jamming transmission without the typical requirement of eavesdropper channel information. We demonstrate the secrecy rate and transmission power tradeoff in active source jamming by providing numerical results on achieved secrecy rate and the bit error rate (BER) at different receivers.
In multiple-input-multiple-output (MIMO) wireless communications, Space Shift Keying (SSK), Spatial modulation (SM) and Generalized Space Shift Keying (GSSK) are three novel MIMO modulation techniques, that can greatly reduce the complexity of MIMO systems. This paper investigates the physical-layer security in typical MIMO systems of these three modulations. We present an exhaustive analysis of secrecy rate for multiple antennas destination and eavesdroppers receivers. Without eavesdroppers channel information, both achievable secrecy rate and bit error rate (BER) are studied through joint modulated signal and jamming signal transmission. Our simulation results demonstrate that the proposed proactive source jamming method achieves improvement of secrecy rate and improved BER performance for multi-antenna users.
Addressing the problem of wireless physical layer security transmission for finite alphabet input systems,a spatial modulation secure transmission method is proposed.On the basis of information theory,the method utilizes the receive antenna indices of multiple-input multiple-output (MIMO) system to bear information,and randomizes the eavesdropper’s equivalent channel by switching the receive antennas,which can guarantee physical layer security transmission.First,the different receiving performances of the legitimate user and eavesdropper are analyzed in the spatial modulation secure transmission system.Second,the mutual information and secrecy mutual information of the transmission system are calculated,and two sufficient conditions that ensure positive secrecy mutual information are pointed out.Finally,an estimation algorithm of mutual information is provided.Moreover,the symmetry of finite alphabet set is exploited to decrease the computational complexity.Theoretical analysis and numerical simulation results verify the availability of the security transmission method.
As a low-complexity and energy efficient MIMO technique, spatial modulation (SM) can avoid inter-channel interference and inter-antenna synchronization. Combining SM with cooperative relaying, the performance of SM can be effectively improved. Since wireless communication is vulnerable to be eavesdropped, the destination-based-jamming (DBJ) technique is applied to the cooperative SM system for security enhancement. In the DBJ scheme, the jamming signal is sent from the legitimate receiver (Bob) to interfere the eavesdropper (Eve). Based on the amplify-and-forward (AF) relaying, we investigate the secrecy performance of the AF relay assisted cooperative SM system with DBJ over Rayleigh fading channels. The achievable rates by Bob and Eve and the corresponding lower bounds are respectively derived. With these low bounds, the approximated closed-form ergodic rates by Bob and Eve can be obtained, respectively. Using these results, the theoretical closed-form ergodic secrecy rate (ESR) of the system can be further derived. The simulation results are provided to confirm the validity of our theoretical analysis. The derived theoretical expressions are consistent with the corresponding simulations and the DBJ scheme is well capable of enhancing the secrecy performance of the cooperative SM system over Rayleigh fading channels.
Achieving secure transmission in wireless network is a significantly important research topic. Classic cryptography encrypts a confidential message to an unreadable cipher message. Thus only the authentic receiver with correct secrecy key is able to decrypt the message. However, with the growing computational capability of adversaries, the requirement of secrecy key generation and distribution is getting stringent. Another method to achieve wireless security, which has attracted much attention in recent years, is through physical layer processing, named physical layer security. In a typical wiretap channel model consisting of a transmitter, a legal receiver and an adversary (illegal receiver), early works have proven that it is possible to achieve positive secrecy rate using multiple antenna techniques, such as beamforming, at the transmitter. In this thesis, we focus on two types of malicious behaviors of the adversary: passive eavesdropping and active attack. For the passive eavesdropping, we first consider the multi-input-single-output (MISO) wiretap channel, in which the legitimate transmitter utilizes the artificial noise aided precoding strategy to maximize the achievable secrecy rate of the channel. Both scenarios of known and unknown channel state information (CSI) for the eavesdropper channels are considered. By deriving the closed-form expression of ergodic secrecy rate, we prove that there exists an optimal power ratio between the information signal and the artificial noise. We then extend our study to a four-node fading channel model in a wireless relay network, which includes two single-antenna users, one single-antenna eavesdropper and one relay node equipped with multiple antennas. By studying the decode-and-forward (DF) scheme, cooperative jamming (CJ) scheme and one proposed hybrid relay scheme, relay-and-jamming (RJ), we aims to find the optimal relay scheme with the condition that the transmitter and the relay node are under individual power constraints and the CSI of the illegitimate channel is only statistically known. Our analysis shows that the hybrid RJ scheme is optimal when the transmitter has a relatively small power budget and/or the transmitter is far away from the intended receiver. Besides the passive eavesdropping, the adversary could also choose the active attack. The pilot spoofing attack is one active attack conducted by the adversary during the channel estimation phase of the legitimate transmission. In practical systems, the pilot signals are usually known \textit{a priori} and repeatedly used information. In this attack, an intelligent adversary spoofs the transmitter on the estimation of CSI by sending the identical pilot signal as the legitimate receiver. By doing so, the adversary could obtain a larger channel rate in the data transmission phase, and also drastically weaken the strength of the received signal at the legitimate receiver if the adversary utilizes large enough power. Due to the serious consequences caused by such an attack, we first propose an energy ratio detector (ERD) that explores the asymmetry of received signal power levels at the transmitter and the legitimate receiver when the attack occurs. Our analysis shows that the ERD could provide very high probability of detection with certain requirement on the false alarming probability. Furthermore, we design a two-way training based scheme to provide not only attack detection but also secure transmission. The two-way training based detector (TWTD) exploits the intrusive component created by the adversary, followed by a secure beamforming-assisted data transmission. In addition to the good detection performance, our scheme could estimate both legitimate and illegitimate channels, with which the beamforming could be designed for data transmission.
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.
Emerging from the information-theoretic characterization of secrecy, physical-layer security exploits the physical properties of the wireless channel for security purpose. In recent years, a great deal of attention has been paid to investigating the physical-layer security issues in multiple-input multiple-output (MIMO) wireless communications. This paper analyzes the secrecy performance of transmit-receive diversity system and spatial multiplexing systems with zero-forcing equalization and minimum mean-square-error equalization. Specifically, exact and asymptotic closed-form expressions are derived for the secrecy outage probability of such MIMO systems in a Rayleigh fading environment, and the corresponding secrecy diversity orders and secrecy array gains are determined. Numerical results are presented to corroborate the analytical results and to examine the impact of various system parameters, including the numbers of antennas at the transmitter, the legitimate receiver, and the eavesdropper. These contributions bring about valuable insights into the physical-layer security in MIMO wireless systems.