In this paper, a novel transmission scheme based on constellation rotation and weighted fractional Fourier transform (WFRFT) is proposed to enhance the physical-layer security in polarization modulation (PM)-based dual-polarized satellite communications. Typically, by appropriately selecting the WFRFT order, the distribution of the signals processed by WFRFT can be close to Gaussian, which makes them difficult to be detected by eavesdroppers. However, once the signals are captured, it is possible for eavesdroppers to recover the information through the WFRFT order scanning method. To overcome this problem, in the proposed scheme, the constellation points are randomly rotated before the WFRFT operation, making it almost impossible to crack the WFRFT order. In this manner, the constellations are distorted, which is difficult for the eavesdropper to demodulate the signals accurately. Furthermore, a robust nonzero secrecy capacity is guaranteed. In addition, the impairment to the PM from the polarization-dependent loss effect is discussed, and a zero-forcing prefilter is applied at the receiver side to mitigate this adverse effect. Finally, the security performance of the proposed scheme is evaluated in terms of the average secrecy capacity and symbol error rate by numerical simulations in dual-polarized satellite communications.
In this paper, a novel transmission scheme based on constellation rotation and weighted fractional Fourier transform (WFRFT) is proposed to enhance the physical-layer security in polarization modulation (PM)-based dual-polarized satellite communications. Typically, by appropriately selecting the WFRFT order, the distribution of the signals processed by WFRFT can be close to Gaussian, which makes them difficult to be detected by eavesdroppers. However, once the signals are captured, it is possible for eavesdroppers to recover the information through the WFRFT order scanning method. To overcome this problem, in the proposed scheme, the constellation points are randomly rotated before the WFRFT operation, making it almost impossible to crack the WFRFT order. In this manner, the constellations are distorted, which is difficult for the eavesdropper to demodulate the signals accurately. Furthermore, a robust nonzero secrecy capacity is guaranteed. In addition, the impairment to the PM from the polarization-dependent loss effect is discussed, and a zero-forcing prefilter is applied at the receiver side to mitigate this adverse effect. Finally, the security performance of the proposed scheme is evaluated in terms of the average secrecy capacity and symbol error rate by numerical simulations in dual-polarized satellite communications.
Polarization state modulation(PM) It is known that satellite communication signals are easy to eavesdrop and how to realize secure transmission is the key problem. This paper proposes a secure transmission scheme based on the polarized constellation rotation and the weighted fractional Fourier transform. Firstly, the pseudo-random sequence is used to process the phase of the two components of polarization signals to make them change randomly, and the constellation points will randomly rotate around the horizontal polarization axis in the Poincare sphere. Then two polarization signals are processed by WFRFT with different orders separately to further distort the polarization constellation. In this manner, the constellation points will be randomly distributed in, on and outside the sphere improve the transmission security. In addition, with the proposed, it is difficult for the eavesdropper to accurately recover the WFRFT parameters and when there are errors in the cracked WFRFT parameters, self-interferences occur in the recovered signals, which causes a decrease in the SNR of the signals received by the eavesdropper. In this way, it also obtains a positive secrecy capacity to ensure the transmission security. Finally, the performance of the proposed scheme is verified from three aspects: polarization constellation distortion, security capacity and the bit error rate performance.
In this paper, a transmission scheme based on polarization filtering and weighted fractional Fourier transform (PF-WFRFT) is proposed to enhance the transmission security in wireless communications. Indeed, the distribution of the transmit signals processed by WFRFT can be close to Gaussian, which can significantly improve the low detection probability. However, through scanning the WFRFT order with small step size, an eavesdropper can restore a regular constellation and crack the information. To overcome the problem, in the PF-WFRFT scheme, two polarized signals with mutually orthogonal polarization state are utilized to convey the information, which are processed by WFRFT separately and added up linearly before being transmitted by dual-polarized antennas. In this manner, even by scanning the WFRFT order, recovered signals are composite ones, which make the WFRFT order and the signals’ PSs difficult to crack, thus improving the security. In addition, the polarization-dependent loss (PDL) effect on the proposed scheme is discussed and a proprocessing matrix based on the channel information is constructed to eliminate this effect. Finally, numerical results are given to demonstrate the security performance of the proposed scheme in wireless communications.
A weighted fractional Fourier transform (WFRFT) based on channel state information (CSI), aiming to safeguard the physical (PHY) layer security of wireless communication system, is proposed. With the proposed scheme, WFRFT is first applied to satellite communications such that the transmitted signal is distorted and can only be neutralized by inverse‐WFRFT with the same parameter. Moreover, by exploiting the physical properties of wireless channels, the CSI matrix is transformed as a secret key. In addition, by adding phase rotation (PR) factors to each branch of the WFRFT system, a new unitary matrix with the encryption properties is constructed, and hence, the satellite communications secrecy is reliably guaranteed due to the variation in signal characteristics. Finally, the efficacy of the security enhancement is evaluated in terms of the average bit error rate (BER) and the secrecy capacity. Simulation results show that the proposed encryption method can make the detection and demodulation more difficult for the eavesdropper.
In this paper, weighted fractional Fourier transform (WFRFT) is employed to safeguard the physical layer (PHY) security of wireless communications. By leveraging the features of WFRFT, we propose a PHY security modulation scheme, which significantly degrades the equivalent signal-to-noise ratio (SNR) of the unauthorized receiver while imposing no impact on the legitimate receiver. With the proposed scheme, a robust nonzero secrecy capacity can be guaranteed. Moreover, the proposed scheme can conceal the actual modulation paradigms to prevent malicious signal detection, due to the variation in signal characteristics. A higher order statistics (HOS) based classifier is used to investigate the anti- recognition performance. Meanwhile, the secrecy performance of the proposed scheme is evaluated in terms of both secrecy capacity and average bit error rate (BER) by numerical simulations. Finally, as a proof-of-concept, an all-digital field programmable gate array (FPGA) based prototype system is developed to validate the practicability of the proposed scheme.
This paper proposes a Weighted fractional Fourier transform (WFRFT) based cooperation scheme to improve PHY layer security against eavesdropping in wireless communications. Rather than dissipating valuable transmission power to jam the eavesdropper, by leveraging the features of WFRFT, the information bearing signal can create “Artificial Noise” effect at the eavesdropper while imposing no effect on the legitimate receiver. Specifically, the proposed WFRFT based cooperation is performed in a two-phase manner, whereby the source first broadcasts its message to the intermediate nodes which then perform WFRFT operation to relay the message to the destination, with the objective of boosting the secrecy rate of the source-destination pair. Simulation results are provided, which demonstrate that the WFRFT-based user cooperation scheme can acehieve a significant performance gain, in terms of secrecy ergodic capacity, compared with conventional security-oriented user cooperation schemes.
In this paper, a weighted fractional Fourier transform(WFRFT) based cooperative overlay system, aiming to guarantee physical layer(PHY) security, is proposed. The paper elaborates how WFRFT and physical layer properties of the wireless medium are collaborated to guarantee the secrecy of wireless transmissions. In the proposed system, WFRFT is first preform on the secret data, such that the transmitted signal is distorted and can only be neutralized by inverse-WFRFT with the same parameter. And then two streams of the transformed sequences that bearing different messages are cooperatively and simultaneously transmitted to two legitimate receivers via a beamforming-liked method, respectively. In general, both the rapid spatial decorrelation property and the inherent security features of WFRFT are leveraged, such that only the eavesdropper’s is degraded, and hence, the wireless communication secrecy is reliably guaranteed. Numerical simulations are conducted to evaluate the performance of the proposed system in terms of the average bit error rate and the secrecy capacity.