物理层安全专栏序言(中英文)

胡爱群

东南大学信息科学与工程学院,南京210096

物理层安全技术特别是无线物理层安全技术,利用通信系统物理层的信息为通信提供安全保护,在网络安全、电子对抗中有着广泛的应用.它利设备指纹对设备身份进行识别,进而实施接入控制;利用信道特征为通信双方建立对称密钥,进而保护传输数据的安全;或者通过加大合法信道与窃听信道的差异,使得敌手的窃听变得更加困难.

近十年来,无线物理层安全技术的研究主要集中在:(1)无线发射机的设备指纹(又称射频指纹,RFF)的提取与识别方法研究;(2)基于无线信道互易性的密钥生成方法研究;(3)与认知无线电网络相结合时带来的用户服务质量(QoS)问题研究;(4)与波束赋形相结合的物理层安全技术研究等.更多的研究集中在前面两点.

在射频指纹的研究方面,重点需要解决的问题是如何提高射频指纹提取的稳定性.发射机发射的信号到达接收机后,在接收机中提取发射机的射频指纹.对射频指纹稳定性影响最大的是无线信道的多径效应,尤其对于宽带发射机而言更是如此.另外,如何增加射频指纹可区分性的研究也在积极开展中.

在基于无线信道互易性的密钥生成方面,如何增强信道互易性、提高密钥生成速率是研究的重点.其中的困难在于存在不同情况的信道,包括静态信道、缓慢移动信道和移动信道.充分研究在不同情况下的信道互易性和随机性,有助于改善密钥生成的性能.目前已有开展主动信道研究的报导,即利用发射机和接收机的多天线配置,在静态和缓慢移动的信道情况下,模仿高速移动通信信道,生成快速变化的信道特性.

本专栏组织了4篇论文,包括1篇综述性论文和3篇不同技术方向的论文.

第一篇是综述性论文《基于设备与信道特征的物理层安全方法》,全面总结了无线物理层安全技术的研究进展和主要应用.阐述了设备指纹的特点、关键技术、研究进展以及可以进一步研究的若干问题;阐述了基于信道特征的密钥生成方法,保障密钥的一致性、随机性、防窃听性等关键技术,以及若干难点研究问题等,指出了无线物理层安全技术的四个未来应用方向.

第二篇论文是《多径传输环境下的射频指纹估计方法》,重点研究了射频指纹与无线信道特征的分离问题.论文基于多天线和多载波现代通信技术,提出了基于主路径分解的射频指纹估计方法,通过重构信号子空间来获取主路径中包含的发射机射频指纹,通过仿真实验验证了方法的有效性,并给出了多径环境下接收机天线数量的建议.

第三篇论文是《不同环境下无线信道密钥生成性能研究》,呈现了三种无线环境下信道互易性的实验结果和密钥生成情况,满足读者了解无线物理层密钥生成的实际性能和可应用性.

第四篇论文是《联合考虑主用户QoS和安全约束下认知NOMA安全传输》,从另一个角度看待无线物理层安全技术.分析了该技术运用到认知无线电网络等多用户环境时,从功率分配的角度,如何分析主用户与次用户之间的服务质量QoS的相互影响,为我们部署无线通信设施提供了有益的参考.

由于篇幅的原因,本专栏组织的内容未能完全覆盖无线物理层安全的所有方面,欢迎从事本方向研究的学者更多地向本刊投稿,进行更多的学术交流.

The physical layer security technology,especially in the wireless field,exploits the inherent physical-layer information of the communication system to provide security protection for communication.It has been widely used in network security and electronic countermeasures.Based on the physical layer security,the device fingerprints are used to identify the device for access control,the channel characteristics are used to establish a pair of symmetric key for both parties to protect the security of transmitted data,or the noise is used to enlarge the channel condition gap to make the eavesdropping more difficult.

In the past ten years,research on wireless physical layer security technologies has mainly focused on the following topics,including

(1)Research on extraction and identification of device fingerprints(also known as radio frequency fingerprints,RFF)of wireless transmitters;

(2)Research on key generation based on the reciprocity of wireless channels;

(3)Research on user quality of service(QoS)issues when combined with cognitive radio networks;

(4)Physical layer security technology research combined with beamforming,etc.

More research has focused on the first two points.

In the research of RF fingerprints,the key problem is how to improve the stability of the extracted RFF features.After the signal transmitted by the transmitter reaches the receiver,the RFF of the transmitter is extracted from the received signal.The major impact on the stability of RF fingerprints is the multipath e ff ect of wireless channels,especially for broadband cases.In addition,some active e ff orts have been made to increase the distinguishability of RFF.

In terms of key generation based on wireless channel reciprocity,the focus of research is how to enhance channel reciprocity and increase key generation rate.The difficulty lies in the existence of different channels,including static channels,slow-moving channels,and mobile channels.Fully studying the channel reciprocity and randomness in different situations will help improve the performance of key generation.At present,there has been some reports of active channel research,which uses the multiple antenna con figurations of the transmitter and receiver to imitate high-speed mobile communication channels under static and slow-moving channel conditions to generate rapidly changing channel characteristics.

This column organizes 4 papers,including 1 review paper and 3 research papers with different technical directions.

In particular,the first one is a review paper“Research on Physical-layer Security Based on Device and Channel Characteristics”,which comprehensively summarizes the research progress and main applications of wireless physical layer security technologies. In the part of device fingerprints,it summarizes key technologies,research progress,and several issues worth studying in the future.For key generation methods based on channel characteristics,it illustrates some key technologies such as guaranteeing key consistency,randomness,and anti-eavesdropping properties,as well as several difficult problems for further study.The authors also point out four future application directions of wireless physical layer security technology.

The second paper is the“Radio Frequency Fingerprint Estimation in Multi-path Transmission Environment”,which focuses on the separation of RF fingerprints from the wireless channel.Based on the multi-antenna and multi-carrier modern communication technology,this paper proposes a method of RF fingerprint estimation based on the decomposition of the main path.The reconstructed signal subspace is used to obtain the RF fingerprint of the transmitter contained in the main path.The validity of the method is verified by simulation experiments and the results provide suggestions for the number of receiver antennas in a multipath environment.

The third paper is“On Key Generation Performance of Wireless Channel in Different Environments”,which presents the experimental results of channel reciprocity and key generation in three wireless environments,which satisfies the reader’s understanding of the performance and applicability of wireless physical layer key generation in real environments.

The fourth paper is“Secure Transmission in Cognitive NOMA Networks under QoS and Security Constraints of Primary User”,which studies wireless physical layer security technology from another perspective.When the technology is applied to multi-user environments such as cognitive radio networks,this paper analyzes the interaction of the quality of service(QoS)between the primary and secondary users from the perspective of power allocation.It provides a useful reference for the deployment of wireless communication facilities.

Due to the space limitation,the content of this column does not fully cover all aspects of wireless physical layer security.Scholars who are engaged in research in this direction are welcome to submit more papers to this journal for more academic exchanges.