Security capacity improvement is always the implementation goal of physical layer security, which can be achieved by deliberate randomization based on differentia and uniqueness of wireless channels through signal processing method. An information-guided randomization secure transmission scheme is proposed combined with a spatial modulation system in which information can be carried by receiving antennas index but actually by channel differentia. Randomization is generated along with channel modulation procedure realized by corresponding preprocessing to transmitting signals. We provide three approaches for designing preprocessing weights under different constraint conditions. The former two can only be used when the number of receiving antennas is less than transmitting and have a tradeoff with varying degrees between receiving performance and security. The third one then relaxes the limits via generalized spatial modulation and can be used for arbitrary antennas configuration but with a receiving performance compromise. Lastly, results of performance analysis and numerical evaluation show that the proposed secure scheme is effective to prohibit the eavesdropper from intercepting information.
Security capacity improvement is always the implementation goal of physical layer security, which can be achieved by deliberate randomization based on differentia and uniqueness of wireless channels through signal processing method. An information-guided randomization secure transmission scheme is proposed combined with a spatial modulation system in which information can be carried by receiving antennas index but actually by channel differentia. Randomization is generated along with channel modulation procedure realized by corresponding preprocessing to transmitting signals. We provide three approaches for designing preprocessing weights under different constraint conditions. The former two can only be used when the number of receiving antennas is less than transmitting and have a tradeoff with varying degrees between receiving performance and security. The third one then relaxes the limits via generalized spatial modulation and can be used for arbitrary antennas configuration but with a receiving performance compromise. Lastly, results of performance analysis and numerical evaluation show that the proposed secure scheme is effective to prohibit the eavesdropper from intercepting information.
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.
Wireless communication security can be enhanced by leveraging the characteristics of the physical (PHY) layer, where discriminatory scrambling can be employed at the symbol level to either improve the signal quality of the legitimate receiver or degrade that of the eavesdroppers. However, in the presence of multiple passive eavesdroppers with more antennas than the transmitter, the transmitted signals can still be reliably separated from random disturbances. To mitigate this challenge, we propose a two-dimensional vectorized secure transmission scheme. Unlike existing transmission schemes (where the same data symbol is sent over each antenna with a predesigned complex weight at a time), in the proposed scheme, a sequence of data symbols in a predefined order (named symbol vector) is first pre-superposed through pre-coding with a random complex matrix prior to been sent as a vector in parallel over each transmitting antenna at a time. As a result, physical randomness of the legitimate channel is introduced into the received signals at passive eavesdroppers in the pre-coding procedure. Moreover, to ensure that transmitted data symbols can be recovered in the right order, each symbol vector is sent repeatedly, according to the principle of maximum entropy. To ensure the intended receiver can recover the transmitted symbol vector, the random pre-coding matrices are selected such that a linear constraint imposed by the CSI of the legitimate channel is satisfied. In addition, an extended maximum likelihood (ML) detection method is developed for the desired receiver while the random pre-coding matrices are not required to be transmitted. We then analyze its security based on the signal detection theory to demonstrate that the intended receiver can recover the transmitted symbol vectors while the eavesdroppers are not capable of doing so. We also evaluate the performance of the proposed scheme to demonstrate its effectiveness.
Linear randomization pre-processing framework was presented to design feasible physical layer secure transmission schemes.The framework show that,based on characteristic differentiae of wireless channels,additive and multiplicative randomization modules with suitable design would create channel advantage for legitimate users.In the view point of information theory security,the optimal distributions of the additive randomization weights and the multiplicative randomization weights to induce the lowest information leakage to the eavesdropper were verified.Finally,A random sub-carrier referencing security scheme was proposed as an instantiation analysis for the optimization design of multiplicative randomization weights.
A physical layer security scheme based on joint antenna and timeslot randomization is proposed which is named Deliberate Symbol Convolution. In this scheme, consecutive phase modulated data symbols are convolved using random weights and the convolved symbols are sent simultaneously over a multi input - single output channel. The legitimate channel is estimated at the transmitter side using pilot symbols transmitted from the legitimate user. It is shown that randomization across timeslots compensates for the constraint on the length of data packets as well as the required number of receive antennas.
In this paper, we propose a novel approach for providing secure wireless communications in transmit-receive diversity systems. In this approach, we precode the information-bearing signal with a uniquely generated randomized eigenvector-based jamming signal to impair the eavesdropper's received signal, while the main channel, the link between the transmitter and the desired receiver, remains unaffected. Unlike existing methods, our approach can be applied to any antenna array configuration, even when the receiver and eavesdropper utilize more antennas than the transmitter, with no benefits to the eavesdropper's information detection capability from employing more antenna elements. Moreover, our proposed approach can provide more degrees of freedom for the jamming signal, significantly increasing the provided level of security. Additionally, our scheme does not assume any knowledge about the eavesdropper or even the number of collaborating eavesdroppers. Our simulation results show a secrecy capacity increase of about 7 bits/s/Hz for a 4 x 4 antenna configuration under typical transmit power constraints, which results in significant improvement in security performance and enables physically secure wireless communications.
A method of using random antenna switching (RAS) is proposed to guarantee the information security during the physical layer transmission. The method uses multiple antennas at the base station and a single antenna at the mobile terminal. The expected mobile terminal (target user) first transmits a training symbol which is used by the base station to estimate the channel. The base station then randomly selects several antennas to transmit each symbol. The weighting coefficients are obtained according to the estimated channel, which is similar to the distributed beamforming except that the magnitudes are random in this paper. Signals from all the selected antennas are finally superimposed in phase at the target user so that the maximum likelihood demodulation can be directly implemented. The RAS makes the channel for an eavesdropper change fast and randomly to prevent the eavesdropper from demodulating the signals. Simulation results show that the target user's bit error rate of RAS is lower with less transmission power than the traditional method of using random weighting coefficients, while the eavesdropper cannot correctly demodulate and hence the low probability of interception is achieved.