Wireless communication system limits the security and privacy because of its broad cast nature. Physical layer security gives secure correspondence and having legitimate user to effectively get secure data. Among the physical layer security techniques, an artificial fast fading (AFF) technique dtrait’s the received signal quality of eavesdroppers by causing pseudo fast fading to the transmitting signals. This is realized by multiplying the signals to be transmitted by random weights every symbol interval. However, the AFF technique often increases the power of the weighted signals. In such cases, the weighted signals must be normalized before transmission. This causes energy loss in the legitimate receiver. Therefore, we consider minimizing the norm of the weight vector to prevent the power of the weighted signals from being increased. In this, we propose and achieve Physical layer secrecy rate in MISO system using artificial fading plus information theory.
Wireless communication system limits the security and privacy because of its broad cast nature. Physical layer security gives secure correspondence and having legitimate user to effectively get secure data. Among the physical layer security techniques, an artificial fast fading (AFF) technique dtrait’s the received signal quality of eavesdroppers by causing pseudo fast fading to the transmitting signals. This is realized by multiplying the signals to be transmitted by random weights every symbol interval. However, the AFF technique often increases the power of the weighted signals. In such cases, the weighted signals must be normalized before transmission. This causes energy loss in the legitimate receiver. Therefore, we consider minimizing the norm of the weight vector to prevent the power of the weighted signals from being increased. In this, we propose and achieve Physical layer secrecy rate in MISO system using artificial fading plus information theory.
For secure wireless communications, physical layer security techniques, which degrade the received signal quality of the eavesdropper, are useful. Among the physical layer security techniques, an artificial fast fading (AFF) technique degrades the received signal quality of eavesdroppers by causing pseudo fast fading to the transmitting signals. This is realized by multiplying the signals to be transmitted by random weights every symbol interval. However, the AFF technique often increases the power of the weighted signals. In such cases, the weighted signals must be normalized before transmission. This causes energy loss in the legitimate receiver. Therefore, we consider minimizing the norm of the weight vector to prevent the power of the weighted signals from being increased. In this paper, we propose three energy efficient AFF generation schemes. In the first scheme, the phases of random weights are adjusted to minimize the norm of the non-random weight which is required to cancel AFF out at the legitimate receiver. In the second scheme, two or more non-random weights are used for minimizing the norm of the weight vector. The third proposed scheme is the combination of these two schemes. Simulation results show that the proposed schemes achieve higher ergodic mutual information as compared with the conventional AFF generation scheme.
For secure wireless communications, physical layer security techniques, which degrade the received signal quality of the eavesdropper, are useful. Among the physical layer security techniques, an artificial fast fading (AFF) technique degrades the received signal quality of eavesdroppers by causing pseudo fast fading to the transmitting signals. This is realized by multiplying the signals to be transmitted by random weights every symbol interval. However, the AFF technique often increases the power of the weighted signals. In such cases, the weighted signals must be normalized before transmission. This causes energy loss in the legitimate receiver. Therefore, we consider minimizing the norm of the weight vector to prevent the power of the weighted signals from being increased. In this paper, we propose three energy efficient AFF generation schemes. In the first scheme, the phases of random weights are adjusted to minimize the norm of the non-random weight which is required to cancel AFF out at the legitimate receiver. In the second scheme, two or more non-random weights are used for minimizing the norm of the weight vector. The third proposed scheme is the combination of these two schemes. Simulation results show that the proposed schemes achieve higher ergodic mutual information as compared with the conventional AFF generation scheme.
Artificial fast fading (AFF) is one of the physical layer security schemes that achieve secure communications. In the AFF scheme, the signal to be transmitted is multiplied by a random weight which is called the AFF weight. As a result, the effect like fast fading is added to the transmitting signal, and the demodulation performance of an eavesdropper is degraded. In contrast, since the AFF weight is generated to be canceled out by the effect of channel between a transmitter and a legitimate receiver, it does not degrade the demodulation performance of the legitimate receiver. In the existing AFF scheme, only single-stream transmission is considered. However, recent wireless communications systems mostly adopt multiple-stream transmission. In this paper, we propose an AFF generation scheme for multiple-input multiple-output (MIMO) systems employing orthogonal frequency division multiplexing (OFDM). Simulation results show that the AFF produced by our AFF generation scheme is successfully canceled out at the legitimate receiver, and the mutual information of the legitimate receiver is increased along with the number of transmitted streams.
We investigate the physical layer security of a multiple-input single-output (MISO) channel in the presence of a multi-antenna passive eavesdropper. Traditionally, artificial noise (AN) scheme is an efficient security strategy without the channel state information (CSI) of the eavesdropper. In this paper, we propose and analyze an efficient security scheme called the artificial fast fading (AFF) scheme. The basic idea is to randomly weight the information symbols at different transmit antennas in a special manner so that the channel of the intended receiver is an AWGN channel while that of the eavesdropper is a fast fading channel. This prevents the eavesdropper obtaining the CSI using the blind channel estimation techniques so that it can only detect the information symbols in a non-coherent way, which greatly reduces the amount of information intercepted. More importantly, we derive the achievable secrecy rate of the sheme and provide a low bound of it, which can be numerically calculated. Compared with the exact secrecy rate of the AN scheme, even the low bound of the AFF scheme is larger, when the eavesdropper has more antennas than the transmitter.
Artificial noise (AN) is an efficient way to enhance physical layer security of multiantenna wiretap channels with a passive eavesdropper (ED) whose channel state information is unavailable. However, the AN is known to be vulnerable to the eavesdropping attack with a large antenna array. To tackle the problem, the artificial fast fading (AFF) scheme has been developed to deliberately randomize the ED's effective channel so as to disrupt its channel estimation. Some recent progress has been made for the secrecy-rate performance of the AFF scheme in the multi-input single-output wiretap channels. However, it turns out that the performance is over-estimated. In this correspondence, we provide a comprehensive analysis on the secrecy-rate of the AFF scheme in general multi-input multi-output wiretap channels. Unfortunately, our analysis reveals a negative result that the conventional AFF is no better than the AN methods, without some pre-shared information among the legitimate parties. This is in fact in stark contrast to the previous observations. Motivated by our analysis, we propose a novel cross layer design by combining the AFF in the physical layer with the secret-keys in the upper layer crypto systems. Then, we mathematically prove that our method asymptotically nullifies the information leakage to the ED in the physical layer for any number of ED antennas even without the aid of the wiretap codes, while further enhancing the upper layer security, and thus provides an enhanced security over the layers. Finally, numerical results demonstrate the accuracy of our analysis and the efficiency of the proposed scheme.
The artificial noise (AN) scheme is an efficient strategy for enhancing the secrecy rate of a multiple-input-single-output channel in the presence of a passive eavesdropper, whose channel state information is unavailable. Recently, a randomized beamforming scheme has been proposed for deteriorating the eavesdropper's bit-error-rate performance via corrupting its receiving signal by time-varying multiplicative noise. However, the secrecy rate of such a scheme has not been well addressed yet. In this paper, we name it the artificial fast fading (AFF) scheme and provide a comprehensive secrecy rate analysis for it. We show that with this scheme, the eavesdropper will face a noncoherent Ricean fading single-input-multiple-output channel. Although the closed-form secrecy rate is difficult to obtain, we derive an exact expression for the single-antenna-eavesdropper case and a lower bound for the multiantenna-eavesdropper case, both of which can be numerically calculated conveniently. Furthermore, we compare the AFF scheme with the AN scheme and show that their respective superiorities to each other depend on the number of antennas that the transmitter and the eavesdropper possessed, i.e., when the eavesdropper has more antennas than the transmitter does, the AFF scheme achieves a larger secrecy rate; otherwise, the AN scheme outperforms. Motivated by this observation, we propose a hybrid AN-AFF scheme and investigate the power allocation problem, which achieves better secrecy performance further.