Robust beamforming for physical-layer secrecy

Junwei Zhang, M. Cenk Gursoy

In this paper, collaborative use of relays to form a beamforming system and provide physical-layer security is investigated. In particular, amplify-and-forward (AF) relay beamforming designs under total and individual relay power constraints are studied with the goal of maximizing the secrecy rates when perfect channel state information (CSI) is available. In the AF scheme, not having analytical solutions for the optimal beamforming design under both total and individual power constraints, an iterative algorithm is proposed to numerically obtain the optimal beamforming structure and maximize the secrecy rates. Robust beamforming designs in the presence of imperfect CSI are investigated for decode-and-forward (DF) based relay beamforming, and optimization frameworks are provided.

Chao Zhou, Changsheng You, Cong Zhou +2 more

Ali A. Nasir, Hoang Duong Tuan, Trung Q. Duong +1 more

Jiaxing Wang, Hengyan Xu, Xin Xie +3 more

Uncrewed aerial vehicles (UAVs) are expected to play a crucial role in future sixth-generation systems and low-altitude communication networks owing to their mobility, flexibility, and wide-range coverage capability. However, the predominance of line-of-sight channels makes UAV communications highly susceptible to eavesdropping, posing significant challenges for secure transmission. Distributed collaborative beamforming has emerged as a promising physical layer security technique for the UAV networks, but its performance is fundamentally constrained by the intrinsic jitter of UAV platforms, which is unavoidable in practical systems. In this paper, a physical layer security scheme is proposed for UAV networks based on collaborative beamforming technologies, within which distinct algorithms are designed according to whether the location of the eavesdropper (EAV) is known or unknown. When the location of the EAV is unknown, the theoretical secrecy performance of the proposed method is derived, and a beamforming strategy is constructed based on the properties of the generalized Rayleigh quotient for the situation of known location. Then, the average secrecy rate of the proposed collaborative beamforming scheme is derived under jitter conditions, and a robust beamforming method is further developed for the scenario in which the location of the EAV is known. Simulation results demonstrate that the average secrecy rate is dramatically improved by the proposed collaborative beamforming scheme compared to the conventional approaches, and a substantial secrecy performance gain is maintained in the presence of UAV jitter.

Jiaxing Cui, Zhengmin Kong, Jing Song +2 more

In this paper, we investigate the physical layer security of a full-duplex decode-and-forward relay-aided system in the worst case, where all channel state informations are realistic imperfect. For the sake of confidentiality of signals transmitted from source to destination, a robust artificial noise (AN)-aided beamforming scheme is proposed. Explicitly, our objective function is that of maximizing the worst-case secrecy rate under the transmit power constraints, by jointly optimizing the beamforming matrix and AN at the source and the relay. To overcome the non-convexity of the robust AN-aided secure beamforming problem, we transform it into multi-block convex problems, where the semi-infinite linear matrix inequality is applied to eliminate the channel uncertainties. As a benefit, our proposed robust AN -aided secure beamforming scheme obtains substantial secrecy performance gains, which verifies the efficiency of the proposed scheme.

Y.-W. Peter Hong, Pang-Chang Lan, C.‐C. Jay Kuo