A novel signaling design for secure transmission over two-user multiple-input
multiple-output non-orthogonal multiple access channel using deep neural
networks (DNNs) is proposed. The goal of the DNN is to form the covariance
matrix of users' signals such that the message of each user is transmitted
reliably while being confidential from its counterpart. The proposed DNN
linearly precodes each user's signal before superimposing them and achieves
near-optimal performance with significantly lower run time. Simulation results
show that the proposed models reach about 98% of the secrecy capacity rates.
The spectral efficiency of the DNN precoder is much higher than that of
existing analytical linear precoders--e.g., generalized singular value
decomposition--and its on-the-fly complexity is several times less than the
existing iterative methods.

提出了一种新的信令设计，利用深度神经网络在多用户多输入多输出非正交多址信道上实现安全传输，并通过模拟结果表明该模型的信道极限接近于 98% 的机密容量率。

MIMO-NOMA 中的安全预编码：一种深度学习方法

Secure Precoding in MIMO-NOMA: A Deep Learning Approach

This letter focuses on the secure transmission for an intelligent reflecting
surface (IRS)-assisted millimeter-wave (mmWave) and terahertz (THz) systems, in
which a base station (BS) communicates with its destination via an IRS, in the
presence of a passive eavesdropper. To maximize the system secrecy rate, the
transmit beamforming at the BS and the reflecting matrix at the IRS are jointly
optimized with transmit power and discrete phase-shift constraints. It is first
proved that the beamforming design is independent of the phase shift design
under the rank-one channel assumption. The formulated non-convex problem is
then converted into two subproblems, which are solved alternatively.
Specifically, the closed-form solution of transmit beamforming at the BS is
derived, and the semidefinite programming (SDP)-based method and element-wise
block coordinate descent (BCD)-based method are proposed to design the
reflecting matrix. The complexity of our proposed methods is analyzed
theoretically. Simulation results reveal that the proposed IRS-assisted secure
strategy can significantly boost the secrecy rate performance, regardless of
eavesdropper's locations (near or blocking the confidential beam).

针对利用智能反射面辅助的毫米波和太赫兹系统的安全传输，通过联合优化基站和反射面的发射波束和反射矩阵，最大化系统保密率。

智能反射面辅助毫米波和太赫兹系统的安全传输

Secure Transmission for Intelligent Reflecting Surface-Assisted mmWave  and Terahertz Systems

This paper investigates a multiple unmanned aerial vehicles (UAVs) enabled
cooperative secure transmission scheme in the presence of multiple potential
eavesdroppers. Specifically, multiple source UAVs (SUAVs) send confidential
information to multiple legitimate ground users and in the meantime multiple
jamming UAVs (JUAVs) cooperatively transmit interference signals to multiple
eavesdroppers in order to improve the legitimate users' achievable secrecy
rate. By taking into account the limited energy budget of UAV, our goal is to
maximize the system secrecy energy efficiency (SEE), namely the achievable
secrecy rate per energy consumption unit, by jointly optimizing the UAV
trajectory, transmit power and user scheduling under the constraints of UAV
mobility as well as the maximum transmit power. The resulting optimization
problem is shown to be a non-convex and mixed-integer fractional optimization
problem, which is challenging to solve. We decompose the original problem into
three sub-problems, and then an efficient iterative algorithm is proposed by
leveraging the block coordinate descent and Dinkelbach method in combination
with successive convex approximation techniques. Simulation results show that
the proposed scheme outperforms the other benchmarks significantly in terms of
the system SEE.

本文提出了一种基于多个无人机的协作安全传输方案，其中多个源无人机发送机密信息给多个合法的地面用户，同时多个干扰无人机协同向多个窃听者发射干扰信号以提高合法用户的可实现保密性，通过共同优化无人机的轨迹、传输功率和用户调度以及无人机的移动性和最大传输功率的约束条件，最大化系统保密能量效率。通过分解问题和提出高效的迭代算法，模拟结果表明，所提出的方案在系统保密能量效率方面明显优于其他基准。

多无人机无线网络中能量高效的合作安全传输

Energy-Efficient Cooperative Secure Transmission in Multi-UAV Enabled  Wireless Networks

Providing secure communications over the physical layer with the objective of
achieving perfect secrecy without requiring a secret key has been receiving
growing attention within the past decade. The vast majority of the existing
studies in the area of physical layer security focus exclusively on the
scenarios where the channel inputs are Gaussian distributed. However, in
practice, the signals employed for transmission are drawn from discrete signal
constellations such as phase shift keying and quadrature amplitude modulation.
Hence, understanding the impact of the finite-alphabet input constraints and
designing secure transmission schemes under this assumption is a mandatory step
towards a practical implementation of physical layer security. With this
motivation, this article reviews recent developments on physical layer security
with finite-alphabet inputs. We explore transmit signal design algorithms for
single-antenna as well as multi-antenna wiretap channels under different
assumptions on the channel state information at the transmitter. Moreover, we
present a review of the recent results on secure transmission with discrete
signaling for various scenarios including multi-carrier transmission systems,
broadcast channels with confidential messages, cognitive multiple access and
relay networks. Throughout the article, we stress the important behavioral
differences of discrete versus Gaussian inputs in the context of the physical
layer security. We also present an overview of practical code construction over
Gaussian and fading wiretap channels, and we discuss some open problems and
directions for future research.

本文评估了近期对于有限字母输入条件下物理层安全的最新进展，并探讨了各种场景下的安全传输技术，最后提出了未来研究方向和存在的问题。