Addressing the wireless digital communication system,a sufficient condition to ensure the physical-layer security transmission is derived from the viewpoint of information theory,and a space hopping secure transmission method is proposed,which can mask the characteristic of finite alphabets. First,since the multi-antenna eavesdropper in the finite-alphabetinput system possesses the architecture of Discrete Noisy Lossless Channel( DNLC),it can reconstruct the secret signal and invalidate the artificial noise method. As a result,destroying the eavesdropper's DNLC architecture becomes a sufficient condition for ensuring the security of system transmission. Then,utilizing the diversity and uniqueness of wireless channel characteristics,a space hopping secure transmission method based on the Multiple Input Multiple Output( MIMO) system is proposed.It switches receiver / transmitter antennas and transmits spatial scrambling during the information transmission,which can mask the finite alphabet characteristic of the secret signal and destroy the eavesdropper's DNLC architecture. Finally,theoretical analysis and simulation results demonstrate the efficacy of the secure method.
Addressing the wireless digital communication system,a sufficient condition to ensure the physical-layer security transmission is derived from the viewpoint of information theory,and a space hopping secure transmission method is proposed,which can mask the characteristic of finite alphabets. First,since the multi-antenna eavesdropper in the finite-alphabetinput system possesses the architecture of Discrete Noisy Lossless Channel( DNLC),it can reconstruct the secret signal and invalidate the artificial noise method. As a result,destroying the eavesdropper's DNLC architecture becomes a sufficient condition for ensuring the security of system transmission. Then,utilizing the diversity and uniqueness of wireless channel characteristics,a space hopping secure transmission method based on the Multiple Input Multiple Output( MIMO) system is proposed.It switches receiver / transmitter antennas and transmits spatial scrambling during the information transmission,which can mask the finite alphabet characteristic of the secret signal and destroy the eavesdropper's DNLC architecture. Finally,theoretical analysis and simulation results demonstrate the efficacy of the secure method.
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.
The spatial scrambling based secure wireless transmission methods, such as artificial noise and antenna array weighted randomly, can secure wireless transmission at the physical layer. They have a common physical essence, that is, the private message is transmitted in the desired direction while deliberate interference is transmitted in other orthogonal directions. Unfortunately, the interference is not white in spatial domain due to the limitation of the transmit antenna number. A eavesdropper can eliminate the directional interferences by the aid of multiple antennas. In this paper, a unified mathematical model for the above physical-layer methods is established, based on which, a MUSIC-like wiretap algorithm is proposed by exploiting the finite alphabet property of communication symbols. Simulation results show that if the eavesdropper has more antennas than that of the transmitter, the proposed algorithm can intercept information effectively.
Recently, MIMO (multiple-input-multiple-output) physical layer secure transmission has attracted great attentions. However, current schemes cannot defend against the passive eavesdroppers with arbitrary number of antennas. To address this problem, in this work, we propose a practical physical layer MIMO secure communication scheme (PLSC) to defend against such an eavesdropper with arbitrary number of antennas. In the proposed scheme, the transmitter first independently generates a random binary sequence as the “key bits (KB)” to “encrypt” (XOR) the confidential information. After that, the transmitter sends the “encrypted information” over the wireless channel, along with mapping key bits to the legitimate receiver simultaneously. The key principle lies in that the KB information is coded in the indexes of the activated/non-activated antennas combination of the legitimate user. Then, the legitimate receiver first observes his/her activated antenna indexes to obtain the corresponding key bits. After that, he/she demodulates the “encrypted information” at the activated antennas, and finally “decrypts” (XOR) the confidential information by using the observed key bits. However, due to the uniqueness and independence of MIMO wireless channel, for any other eavesdroppers who suffer an independent channel from legitimate users, we prove that it cannot observe any information about KB from the received signals, regardless of how many antennas it has used. Consequently, without knowledge of KB, it cannot decrypt any information about the confidential information, too. The reliability and security of PLSC are theoretically demonstrated. The simulation and numerical results fully verified the validity and effectiveness of the proposed scheme.
A scheme based on projection operator is proposed to guarantee the information theoretical security in MIMO physical layer transmission.The transmitter has multiple antennas and is able to simultaneously transmit separately information bearing signal to the intended receiver and randomized interference to the eavesdropper in the projection space.An iterative algorithm of power allocation between them is given according to the secret channel capacity criteria.Based on the special statistical distributions of the adversary’s received signal,the indeterminacy of its blind deconvolution is proved.Numerical results indicate that the secret channel capacity of this scheme is enhanced with reduced bit error rate at the target user,while the eavesdropper can not demodulate correctly.
Secure wireless communication has always been a hot research topic due to the vulnerabilities associated with wireless channel. Physical layer aspects to secure wireless communication, based on the information-theoretic security and signal processing methods have gained much recognition over the last decade. Specifically, artificial noise (AN) methods are assumed to be good means for providing security against potential eavesdroppers in multi-input multi-output (MIMO) systems and/or relay systems. However, there are still a large number of nodes which do not have multi-antennas or support sophisticated protocols in wireless networks. In this paper, a novel AN-aided method is proposed to secure wireless communications between the legitimate users (not equipped with multiple antennas) in the presence of an eavesdropper. In this proposed method frequency selective property of wireless channel is exploited. The basic principle is same in which transmitter generate random AN signal utilizing some of the transmission power to confuse eavesdropper. However artificial noise is generated in such a way that it appears to be zero at the sampling time, only for the legitimate receiver while degrading eavesdropper's channel. Artificial noise is specified using the channel state information (CSI) of the legitimate users' link. However, the secrecy of proposed scheme doesn't depend on the secrecy of CSI. Extensive simulation suggests that the proposed scheme can effectively utilized for securing wireless transmissions.
Broadband wireless communication is implemented primarily in a complicated environment. The complex environment with time-varying multi-path propagation characteristics will seriously affect the performance of communication. To solve the problem of insecurity in information transmission in wireless channels, in this paper a system is modeled by using the multi-input single output eavesdropping channel model and the security of information transmission through time reversal technology is ensured. Another problem is that the information focuses on the receiving point. Owing to the temporal and spatial focusing characteristics of the time reversal technology the information near the receiving point can be eavesdropped easily. To solve this problem, a secure transmission scheme based on time reversal technology with artificial noise interference on the transmitter side is proposed. One of the core technologies to solve this problem is to introduce the environment adaptive technique–time reversal in the wireless link. Further, the problem of a wiretap channel in physical layer security research has become a popular research topic in recent years. To solve the problems about the physical layer wiretap channel and multi-path fading in wireless channels, a novel concept combining time reversal technology with physical layer security technology is proposed. In this paper, a physical layer secure transmission scheme based on the joint time reversal technique and artificial noise at the sending end is proposed for the wireless multi-path channel. First, in a typical wiretap channel model the time reversal technique is used to improve the security of the information transmission process by using the properties of spatial and temporal focusing. It refers to the fact that information can be focused at a given moment and in space. Second, as the information is easily eavesdropped near the focus point, artificial noise is added to the sending end to disrupt the ability of the eavesdropper to eavesdrop. The artificial noise has no effect on legitimate user due to the use of null-space artificial noise in legitimate user. Based on this scheme, a closed expression, such as secure signal-to-interference and signal-to-noise ratio, an achievable secrecy rate and bit error rate are obtained, and the influences of the number of antennas, signal-to-noise ratio, and artificial noise are analyzed. The theoretical analysis and simulation results show that the proposed scheme has a higher secrecy signal-to-noise ratio, a higher rate of secrecy, and a lower bit error rate of the legitimate user than the the existing physical layer security schemes.