Physical-Layer Key Generation Based on Multipath Channel Diversity Using Dynamic Metasurface Antennas

Physical layer key generation(PKG)technology leverages the reciprocal channel randomness to generate the shared secret keys.The low secret key capacity of the existing PKG schemes is due to the reduction in degree-of-freedom from multipath fading channels to multipath combined channels.To improve the wireless key generation rate,we propose a multipath channel diversity-based PKG scheme.Assisted by dynamic metasurface antennas(DMA),a two-stage multipath channel parameter estimation algorithm is proposed to efficiently realize super-resolution multipath parameter estimation.The proposed algorithm first estimates the angle of arrival(AOA)based on the reconfigurable radiation pattern of DMA,and then utilizes the results to design the training beamforming and receive beamforming to improve the estimation accuracy of the path gain.After multipath separation and parameter estimation,multi-dimensional independent path gains are utilized for generating secret keys.Finally,we analyze the security and complexity of the proposed scheme and give an upper bound on the secret key capacity in the high signal-to-noise ratio(SNR)region.The simulation results demonstrate that the proposed scheme can greatly improve the secret key capacity compared with the existing schemes.

考虑轴向均布载荷时线弹性支承压杆的稳定性计算

为了计算考虑轴向均布载荷时线弹性支承压杆的稳定性,首先用压杆微元段的静力平衡条件,建立了其变形和内力的近似方程;接着由变形边界条件、内力边界条件、内力与外力的关系、外力与变形的关系,确定了一个包含12个初参数的齐次线性方程组,由方程组有非零解的条件,导出了临界载荷的特征方程;最后以6个线弹性支承的压杆为例,进行了稳定性计算,绘制了轴向均布载荷与集中载荷的近似关系曲线,给出了这些曲线在坐标轴上的截距的数值解,发现每条曲线的走势以及它们所代表的压杆的稳定性排序关系,较符合理论预期。

Dual-Threshold Based Secure On-Off Transmission Scheme for Dense HCNs with Imperfect CSI

In this paper, we propose a dual-threshold based secure On-Off transmission scheme, where signals are transmitted only if the channel condition can guarantee secure and reliable communication. First, we present a dynamic access strategy to increase access efficiency, which provides an access region for the intended user. Then, we propose an emission control policy to transmit signals according to the current channel condition, which declines the influence of channel estimation errors and guarantees qualities of communication links. Furthermore, we give a comprehensive performance analysis for the proposed scheme in terms of connection outage probability(COP) and secrecy outage probability(SOP), and present a dual-threshold optimization model to further support the performance. Numerical results verify that the secure On-Off transmission scheme can increase the system secure energy efficiency and guarantee reliable and secure communication.

Physical Layer Security of Multi-hop Aided Downlink MIMO heterogeneous Cellular Networks

This study investigates physical layer security in downlink multipleinput multiple-output(MIMO) multi-hop heterogeneous cellular networks(MHCNs),in which communication between mobile users and base stations(BSs) is established by a single or multiple hops,to address the problem of insufficient security performance of MIMO heterogeneous cellular networks.First,two-dimensional homogeneous Poisson point processes(HPPPs) are utilized to model the locations of K-tier BSs in MIMO MHCNs and receivers,including those of legitimate users and eavesdroppers.Second,based on the channel gain distribution and the statistics property of HPPP,the achievable ergodic rates of the main and eavesdropper channels in direct and ad hoc links are derived,respectively.Third,the secrecy coverage probability and the achievable ergodic secrecy throughput of downlink MIMO MHCNs are explored,and their expressions are derived.Lastly,the correctness of the theoretical derivation is verified through Monte Carlo simulations.

Secure Transmission Scheme Based on Dual-Thresholds for Simultaneous Wireless Information and Power Transfer

This paper studies a simultaneous wireless information and power transfer system with multiple external eavesdroppers and internal curious users.We model the random network by Poisson cluster process in consideration of the case where eavesdroppers hide around certain targets.Focusing on the users that work in harvesting-transmitting mode with time switching receivers,we establish communication model via time division multiple access.On this basis,we propose a lightweight secure transmission scheme based on dual-thresholds for physical-layer security enhancement,which consists of two protocols applied to the downlink(DL) and uplink(UL) transmission respectively.In the DL,we design a dynamic information-power switching transmission protocol based on signal-to-noise ratio threshold,which provides an opportunistic approach to reform the fixed period allocation of information and power transfer;in the UL,an energy threshold is proposed for users to control the transmission,which is called a user-led on-off transmission protocol.Furthermore,we give a comprehensive performance analysis for the proposed scheme in terms of delay,reliability,security and secrecy throughput.Based on the analysis results,we optimize the two thresholds and the DL-UL allocationcoefficient to maximize the secrecy throughput.Simulation results show the proposed scheme can bring about a substantial secrecy gain.

Secure Spectral-Energy Efficiency Tradeoff in RandomCognitive Relay Networks

Spectral efficiency(SE) and energy efficiency(EE) in secure communications is of primary importance due to the fact that 5 G wireless networks aim to achieve high throughput,low power consumption and high level of security.Nevertheless,maximizing SE and EE are not achievable simultaneously.In this paper,we investigate the SE and EE tradeoff for secure transmission in cognitive relay networks where all nodes are randomly distributed.We first introduce the opportunistic relay selection policy,where each primary transmitter communicates with the primary receiver with the help of a secondary user as a relay.Then,we evaluate the secure SE and secure EE of the primary network based on the outage probabilities analysis.Thirdly,by applying a unified SE-EE tradeoff metric,the secure SE and EE tradeoff problem is formulated as the joint secure SE and EE maximization problem.Considering the non-concave feature of the objective function,an iterative algorithm is proposed to improve secure SE and EE tradeoff.Numerical results show that the opportunistic relay selection policy is always superior to random relay selection policy.Furthermore,the opportunistic relay selection policy outperforms conventional direct transmission policy when faced with small security threat(i.e.,for smaller eavesdropper density).

A Physical Layer Authentication Mechanism for IoT Devices

When Internet of Things(IoT)nodes access the network through wireless channels,the network is vulnerable to spoofing attacks and the Sybil attack.However,the connection of massive devices in IoT makes it difficult to manage and distribute keys,thus limiting the application of traditional high-level authentication schemes.Compared with the high-level authentication scheme,the physical layer authentication scheme realizes the lightweight authentication of users by comparing the wireless channel characteristics of adjacent packets.However,traditional physical layer authentication schemes still adopt the one-to-one authentication method,which will consume numerous network resources in the face of large-scale IoT node access authentication.In order to realize the secure access authentication of IoT nodes and regional intrusion detection with low resource consumption,we propose a physical layer authentication mechanism based on convolution neural network(CNN),which uses the deep characteristics of channel state information(CSI)to identify sending nodes in different locations.Specifically,we obtain the instantaneous CSI data of IoT sending nodes at different locations in the pre-set area,and then feed them into CNN for training to procure a model for IoT node authentication.With its powerful ability of data analysis and feature extraction,CNN can extract deep Spatio-temporal environment features of CSI data and bind them with node identities.Accordingly,an authentication mechanism which can distinguish the identity types of IoT nodes located in different positions is established to authenticate the identity of unknown nodes when they break into the pre-set area.Experimental results show that this authentication mechanism can still achieve 94.7%authentication accuracy in the case of a low signalto-noise ratio(SNR)of 0 dB,which means a significant improvement in authentication accuracy and robustness.

5G ENTERING INTO A NEW ERA

The ever increasing wireless data services, such asimaging, video, audio, multimedia, etc., have de-mands for the very high speed wireless communicationsand network, which are unfortunately a bottleneck whencombining with the wireline core network. Users＇ arenow expecting high quality of experience with low-costdevices, ubiquitous connectivity, energy efficiency, highreliability, or even ultra-low latency if a vehicle terminalis applied.

6G无线内生安全理念与构想

6G开放融合、异构共存、智能互联的网络特点将引发更多未知复杂安全威胁,目前安全滞后于通信发展的格局必然难以应对,6G时代必须打破思维定势,催生真正具有代际效应的标志性技术.内生安全从无线网络内源性缺陷产生的共性和本源安全问题出发,通过结构导向的解决方法,具有抵御未知安全威胁的能力和通信/安全/服务内源性融合的能力.本文对6G无线网络内生安全问题、理念进行了探讨,并提出内生安全在6G超高速宽带通信、超大连接超低时延、天地一体化全域覆盖等典型场景中的应用构想,给出了若干潜在关键技术和解决方案.

Pattern-reconfigurable antenna-assisted secret key generation from multipath fading channels

Physical layer key generation(PKG)technology leverages reciprocal channel randomness to generate shared secret keys.However,multipath fading at the receiver may degrade the correlation between legitimate uplink and downlink channels,resulting in a low key generation rate(KGR).In this paper,we propose a PKG scheme based on the pattern-reconfigurable antenna(PRA)to boost the secret key capacity.First,we propose a reconfigurable intelligent surface(RIS)based PRA architecture with the capability of flexible and reconfigurable antenna patterns.Then,we present the PRA-based PKG protocol to improve the KGR via mitigation of the effects of multipath fading.Specifically,a novel algorithm for estimation of the multipath channel parameters is proposed based on atomic norm minimization.Thereafter,a novel optimization method for the matching reception of multipath signals is formulated based on the improved binary particle swarm optimization(BPSO)algorithm.Finally,simulation results show that the proposed scheme can resist multipath fading and achieve a high KGR compared to existing schemes.Moreover,our findings indicate that the increased degree of freedom of the antenna patterns can significantly increase the secret key capacity.

基于空域对称加扰和安全极化编码的无协商密钥生成方法

针对现有密钥生成方法流程繁琐的问题,本文利用空域对称加扰和安全极化编码提出了一种无协商的密钥生成方法,仅需安全传输和隐私放大两步即可生成密钥.首先,空域对称加扰以类信号噪声代替传统的Gauss噪声具有更高的安全性并为合法信道提供了信道优势,保证了安全容量的存在性;然后,基于该信道优势和系统性能需求提出了基于Gauss近似和遗传算法的安全极化码构造算法,确保了传输比特的安全性;最后,利用安全极化编码和空域对称加扰实现了私密比特的安全传输,并对其进行隐私放大生成密钥.仿真结果验证了空域对称加扰和安全极化编码的有效性,并进一步说明了所提密钥生成方法能够满足系统性能的需求. NIST测试结果表明了生成的密钥具有很强的随机性.

5G安全技术研究与标准进展

随着第五代移动通信系统(5th generation wireless systems,5G)及其演进系统的商用和其在物联网、车联网等垂直领域的融合发展,其安全问题越来越受到关注.本文从潜在威胁、安全架构和安全技术3个方面阐述了相关研究进展.首先,根据攻击者对系统有效性、信息完整性、身份认证、隐私和机密性保护的不同安全目标,将5G潜在的安全威胁进行了分类,分析了各个层次可能面临的威胁与攻击手段.其次,简述了相关标准中的5G安全架构,讨论了5G及其演进系统潜在的物理层、网络层和应用层安全技术.最后,本文指出了未来继续提升5G及B5G安全的潜在研究方向.

基于3D波束成形的隐蔽无线通信威胁区域构建

为了实时且直观地评估当前隐蔽无线通信系统所面临的未知非法检测威胁,本文首次定义了隐蔽威胁区域并设计了相应轻量级算法.首先,在莱斯衰落信道和噪声不确定条件下构建了基于3D波束成形的下行隐蔽无线通信系统模型,分析了敌方最优检测性能,推导了系统最小平均隐蔽概率;然后,给出了通信速率及连接中断概率闭式表达式,求解了给定敌方位置时的系统最大化隐蔽吞吐量优化问题;最后,针对实际通信场景中无法获知敌方位置或分布规律的情形,定义了系统隐蔽威胁区域这一新的性能指标,并设计了相应轻量级算法.仿真结果验证了系统的隐蔽性能、总体性能,以及所提算法性能,揭示了背景噪声、信道环境、天线构造和系统要求等主要参数对隐蔽威胁区域的影响.

静态场景下基于RIS天线的物理层密钥生成方案

针对静态环境下密钥容量低的问题,首次将RIS天线配置在基站设备端用于密钥生成,通过捷变控制RIS单元相移变化,生成随机快变波束,并与原通信信道合并构成新的等价通信信道,从而使密钥容量不受制于自然信道变化速度.然后推导了该方案下密钥容量闭式解,理论分析及仿真表明使用有限单元即可达到与快变信道环境下同等性能,相较于RIS作为反射面部署的方案,在密钥容量增益和防信息泄露等方面具有明显优势.为进一步发挥RIS增益,提出将部分单元用于密钥生成,部分单元用于波束赋形的联合设计方案,推导了该方案下闭式解.最后,在满足密钥容量和通信性能的基础上,给出了最优资源分配策略,仿真表明可以实现密钥容量与通信性能联合提升.

Discussion on a new paradigm of endogenous security towards 6G networks

The sixth-generation mobile communication(6G)networks will face more complex endogenous security problems,and it is urgent to propose new universal security theories and establish new practice norms to deal with theªunknown unknownºsecurity threats in cyberspace.This paper first expounds the new paradigm of cyberspace endogenous security and introduces the vision of 6G cyberspace security.Then,it analyzes the security problems faced by the 6G core network,wireless access network,and emerging associated technologies in detail,as well as the corresponding security technology development status and the integrated development of endogenous security and traditional security.Furthermore,this paper describes the relevant security theories and technical concepts under the guidance of the new paradigm of endogenous security.