Residual loop-interference(LI)poses a significant challenge for the full-duplex(FD)unmanned aerial vehicle(UAV).To address the issue of residual LI,this paper proposes an amplify-and-forward(AaF)FD-UAV relay system ba...Residual loop-interference(LI)poses a significant challenge for the full-duplex(FD)unmanned aerial vehicle(UAV).To address the issue of residual LI,this paper proposes an amplify-and-forward(AaF)FD-UAV relay system based on a novel orthogonal frequency division multiplexing(OFDM)technique,in which a signal model of infinite impulse response(IIR)is established,instead of the classical finite impulse response(FIR).In the proposed scheme,the residual LI is considered a useful signal and can be combined with the novel OFDM to establish the IIR signal model.Meanwhile,the guard interval(GI)is designed to maintain the circular convolution structure,which differs from the cyclic prefix(CP)applied by the classical OFDM.At the receiver,the IIR signals are influenced only by Gaussian white noise.The proposed FD-UAV relay system can maintain a satisfactory bit error rate(BER)even in the presence of significant residual LI,compared to conventional solutions for suppressing LI on FD-UAV relay.Numerical simulations validate that our proposed scheme offers a fresh solution to the residual LI problem in FD-UAV communication.展开更多
针对正交频分复用(Orthogonal Frequency Division Multiplex,OFDM)通信感知一体化(Integrated Sensing and Communication,ISAC)系统在高动态场景下存在的载波间干扰(Inter-Carrier Interference,ICI)问题,提出一种两步式ICI抑制方法,...针对正交频分复用(Orthogonal Frequency Division Multiplex,OFDM)通信感知一体化(Integrated Sensing and Communication,ISAC)系统在高动态场景下存在的载波间干扰(Inter-Carrier Interference,ICI)问题,提出一种两步式ICI抑制方法,解决现有方法在高动态场景中ICI抑制性能不足、通信速率受限的难题。所提方法设定合适的模糊数取值,通过模糊数遍历的多普勒补偿和目标峰值对比,实现目标速度的无模糊精确估计;基于估计结果重构无ICI的目标信号。仿真结果表明,相较于现有方法,所提方法在不牺牲通信速率的前提下,对不同多普勒效应具有优良的抗ICI和速度估计性能,为高动态场景下的OFDM-ISAC实现提供了一种技术方案。展开更多
The radio frequency(RF)fingerprint technique is a robust method for security enhancement of the physical layer by leveraging the unique RF imperfections inherent in various wireless devices.Among these imperfections,t...The radio frequency(RF)fingerprint technique is a robust method for security enhancement of the physical layer by leveraging the unique RF imperfections inherent in various wireless devices.Among these imperfections,the carrier frequency offset(CFO)stands out as a primary RF fingerprint(RFF)of the transmitter,offering the potential to distinguish among different transmitters.However,accurately estimating CFO in time-varying channels poses significant challenges due to multipath effects and Doppler shifts.In this paper,we focus on estimating CFO for wireless device identification in the orthogonal frequency division multiplexing(OFDM)communication system.To achieve precise CFO estimation under time-varying channels,we propose a frequency domain correlation and spline interpolation(FCSI)algorithm.This approach utilizes pilots distributed across different subcarriers to correlate with prior local sequences,facilitating accurate CFO estimation.Classification is then performed based on the Euclidean distance between the prior RFF and the tested RFF dataset.Simulation results demonstrate that the proposed Mconsecutive average method effectively reduces the classification error rate in the challenging high-frequency(HF)skywave channel environment.展开更多
随着数字化技术和雷达系统的发展,针对合成孔径雷达(Synthetic Aperture Radar,SAR)的干扰对抗技术不断进步,尤其是基于数字射频存储技术(Digital Radio Frequency Memory,DRFM)产生的有源欺骗干扰为SAR成像系统带来了前所未有的考验。...随着数字化技术和雷达系统的发展,针对合成孔径雷达(Synthetic Aperture Radar,SAR)的干扰对抗技术不断进步,尤其是基于数字射频存储技术(Digital Radio Frequency Memory,DRFM)产生的有源欺骗干扰为SAR成像系统带来了前所未有的考验。针对欺骗干扰开展SAR成像抗干扰方法研究,本文基于相位编码波形与带有循环前缀的正交频分复用(Cyclic Prefix Orthogonal Frequency Division Multiplexing,CP-OFDM)波形进行正交波形设计,提出了相位编码CP-OFDM正交波形。基于CP-OFDM波形的循环前缀(Cyclic Prefix,CP)特征,引入基于线性模型的脉冲压缩方法对相位编码CP-OFDM正交波形的SAR成像回波进行距离向处理,能够实现无旁瓣干扰的自相关脉冲压缩。通过对相位编码CP-OFDM波形的时域相位进行编码优化设计,可以实现不同相位编码CP-OFDM波形之间良好的互相关性能。基于线性模型脉冲压缩方法改善了一种p范数多波形加权循环(p-norm Weighted Cyclic Algorithm,p-WeCAN)波形优化算法,采用该算法对相位编码CP-OFDM波形集的相位编码序列进行优化设计,优化后波形的互相关脉冲压缩结果的峰值水平(Peak Sidelobe Level,PSL)相比于随机相位编码CP-OFDM波形的互相关PSL改善了2 dB左右。CP特性赋予了相位编码CP-OFDM波形良好的自相关脉冲压缩结果,相位编码优化设计提供了良好的互相关脉冲压缩结果,采用该正交波形集进行SAR成像,能够实现对欺骗干扰的抑制。进行了点目标、面目标和基于GF-3回波数据反演的半实测数据的抗欺骗干扰SAR成像仿真,与基于线性调频(Linear Frequency Modulation,LFM)波形的欺骗干扰条件下的成像结果进行对比,验证了相位编码CP-OFDM对欺骗干扰的抑制能力。展开更多
电力线通信是构建电力物联网的一种可靠、有效的通信技术,然而电力线信道的广播特性使得其极易成为被窃听对象。为解决电力线信道的安全隐患,文章基于正交频分复用(orthogonal frequency division multiplexing,OFDM)的演进技术即正交...电力线通信是构建电力物联网的一种可靠、有效的通信技术,然而电力线信道的广播特性使得其极易成为被窃听对象。为解决电力线信道的安全隐患,文章基于正交频分复用(orthogonal frequency division multiplexing,OFDM)的演进技术即正交频分复用索引调制(OFDM with index modulation,OFDM-IM)及人工噪声(artificial noise,AN)技术研究了一种OFDM-IM-AN-PLC方案。在多径衰落的电力线信道下,研究了收发两端获得不完整信道状态信息(channel state information,CSI)情形下该方案的误码率性能及安全性能。实验结果证明,即使在收发双方获得不完整CSI情况下,OFDM-IM-AN-PLC方案仍能为电力线信道传输带来安全性。展开更多
在室内可见光通信中符号间干扰和噪声会严重影响系统性能,K均值(K-means)均衡方法可以抑制光无线信道的影响,但其复杂度较高,且在聚类边界处易出现误判。提出了改进聚类中心点的K-means(Improved Center K-means,IC-Kmeans)算法,通过随...在室内可见光通信中符号间干扰和噪声会严重影响系统性能,K均值(K-means)均衡方法可以抑制光无线信道的影响,但其复杂度较高,且在聚类边界处易出现误判。提出了改进聚类中心点的K-means(Improved Center K-means,IC-Kmeans)算法,通过随机生成足够长的训练序列,然后将训练序列每一簇的均值作为K-means聚类中心,避免了传统K-means反复迭代寻找聚类中心。进一步,提出了基于神经网络的IC-Kmeans(Neural Network Based IC-Kmeans,NNIC-Kmeans)算法,使用反向传播神经网络将接收端二维数据映射至三维空间,以增加不同簇之间混合数据的距离,提高了分类准确性。蒙特卡罗误码率仿真表明,IC-Kmeans均衡和传统K-means算法的误码率性能相当,但可以显著降低复杂度,特别是在信噪比较小时。同时,在室内多径信道模型下,与IC-Kmeans和传统Kmeans均衡相比,NNIC-Kmeans均衡的光正交频分复用系统误码率性能最好。展开更多
基金the National Natural Science Foundation of China(No.62001333,No.52207167)the Scientific Research Project of Education Department of Hubei Province(No.D20221702)Hunan Provincial Natural Science Foundation(No.2022JJ50181)。
文摘Residual loop-interference(LI)poses a significant challenge for the full-duplex(FD)unmanned aerial vehicle(UAV).To address the issue of residual LI,this paper proposes an amplify-and-forward(AaF)FD-UAV relay system based on a novel orthogonal frequency division multiplexing(OFDM)technique,in which a signal model of infinite impulse response(IIR)is established,instead of the classical finite impulse response(FIR).In the proposed scheme,the residual LI is considered a useful signal and can be combined with the novel OFDM to establish the IIR signal model.Meanwhile,the guard interval(GI)is designed to maintain the circular convolution structure,which differs from the cyclic prefix(CP)applied by the classical OFDM.At the receiver,the IIR signals are influenced only by Gaussian white noise.The proposed FD-UAV relay system can maintain a satisfactory bit error rate(BER)even in the presence of significant residual LI,compared to conventional solutions for suppressing LI on FD-UAV relay.Numerical simulations validate that our proposed scheme offers a fresh solution to the residual LI problem in FD-UAV communication.
文摘针对正交频分复用(Orthogonal Frequency Division Multiplex,OFDM)通信感知一体化(Integrated Sensing and Communication,ISAC)系统在高动态场景下存在的载波间干扰(Inter-Carrier Interference,ICI)问题,提出一种两步式ICI抑制方法,解决现有方法在高动态场景中ICI抑制性能不足、通信速率受限的难题。所提方法设定合适的模糊数取值,通过模糊数遍历的多普勒补偿和目标峰值对比,实现目标速度的无模糊精确估计;基于估计结果重构无ICI的目标信号。仿真结果表明,相较于现有方法,所提方法在不牺牲通信速率的前提下,对不同多普勒效应具有优良的抗ICI和速度估计性能,为高动态场景下的OFDM-ISAC实现提供了一种技术方案。
基金supported by ZTE Industry-University-Institute Cooperation Funds under Grant No.IA20240723011National Natural Science Foundation of China under Grant No.62371123+1 种基金Young Elite Scientists Sponsorship Program of the Beijing High Innovation Plan under Grant No.20251077Research Fund of National Mobile Communications Research Laboratory,Southeast University under Grant No.2023A03。
文摘The radio frequency(RF)fingerprint technique is a robust method for security enhancement of the physical layer by leveraging the unique RF imperfections inherent in various wireless devices.Among these imperfections,the carrier frequency offset(CFO)stands out as a primary RF fingerprint(RFF)of the transmitter,offering the potential to distinguish among different transmitters.However,accurately estimating CFO in time-varying channels poses significant challenges due to multipath effects and Doppler shifts.In this paper,we focus on estimating CFO for wireless device identification in the orthogonal frequency division multiplexing(OFDM)communication system.To achieve precise CFO estimation under time-varying channels,we propose a frequency domain correlation and spline interpolation(FCSI)algorithm.This approach utilizes pilots distributed across different subcarriers to correlate with prior local sequences,facilitating accurate CFO estimation.Classification is then performed based on the Euclidean distance between the prior RFF and the tested RFF dataset.Simulation results demonstrate that the proposed Mconsecutive average method effectively reduces the classification error rate in the challenging high-frequency(HF)skywave channel environment.
文摘随着数字化技术和雷达系统的发展,针对合成孔径雷达(Synthetic Aperture Radar,SAR)的干扰对抗技术不断进步,尤其是基于数字射频存储技术(Digital Radio Frequency Memory,DRFM)产生的有源欺骗干扰为SAR成像系统带来了前所未有的考验。针对欺骗干扰开展SAR成像抗干扰方法研究,本文基于相位编码波形与带有循环前缀的正交频分复用(Cyclic Prefix Orthogonal Frequency Division Multiplexing,CP-OFDM)波形进行正交波形设计,提出了相位编码CP-OFDM正交波形。基于CP-OFDM波形的循环前缀(Cyclic Prefix,CP)特征,引入基于线性模型的脉冲压缩方法对相位编码CP-OFDM正交波形的SAR成像回波进行距离向处理,能够实现无旁瓣干扰的自相关脉冲压缩。通过对相位编码CP-OFDM波形的时域相位进行编码优化设计,可以实现不同相位编码CP-OFDM波形之间良好的互相关性能。基于线性模型脉冲压缩方法改善了一种p范数多波形加权循环(p-norm Weighted Cyclic Algorithm,p-WeCAN)波形优化算法,采用该算法对相位编码CP-OFDM波形集的相位编码序列进行优化设计,优化后波形的互相关脉冲压缩结果的峰值水平(Peak Sidelobe Level,PSL)相比于随机相位编码CP-OFDM波形的互相关PSL改善了2 dB左右。CP特性赋予了相位编码CP-OFDM波形良好的自相关脉冲压缩结果,相位编码优化设计提供了良好的互相关脉冲压缩结果,采用该正交波形集进行SAR成像,能够实现对欺骗干扰的抑制。进行了点目标、面目标和基于GF-3回波数据反演的半实测数据的抗欺骗干扰SAR成像仿真,与基于线性调频(Linear Frequency Modulation,LFM)波形的欺骗干扰条件下的成像结果进行对比,验证了相位编码CP-OFDM对欺骗干扰的抑制能力。
文摘电力线通信是构建电力物联网的一种可靠、有效的通信技术,然而电力线信道的广播特性使得其极易成为被窃听对象。为解决电力线信道的安全隐患,文章基于正交频分复用(orthogonal frequency division multiplexing,OFDM)的演进技术即正交频分复用索引调制(OFDM with index modulation,OFDM-IM)及人工噪声(artificial noise,AN)技术研究了一种OFDM-IM-AN-PLC方案。在多径衰落的电力线信道下,研究了收发两端获得不完整信道状态信息(channel state information,CSI)情形下该方案的误码率性能及安全性能。实验结果证明,即使在收发双方获得不完整CSI情况下,OFDM-IM-AN-PLC方案仍能为电力线信道传输带来安全性。
文摘在室内可见光通信中符号间干扰和噪声会严重影响系统性能,K均值(K-means)均衡方法可以抑制光无线信道的影响,但其复杂度较高,且在聚类边界处易出现误判。提出了改进聚类中心点的K-means(Improved Center K-means,IC-Kmeans)算法,通过随机生成足够长的训练序列,然后将训练序列每一簇的均值作为K-means聚类中心,避免了传统K-means反复迭代寻找聚类中心。进一步,提出了基于神经网络的IC-Kmeans(Neural Network Based IC-Kmeans,NNIC-Kmeans)算法,使用反向传播神经网络将接收端二维数据映射至三维空间,以增加不同簇之间混合数据的距离,提高了分类准确性。蒙特卡罗误码率仿真表明,IC-Kmeans均衡和传统K-means算法的误码率性能相当,但可以显著降低复杂度,特别是在信噪比较小时。同时,在室内多径信道模型下,与IC-Kmeans和传统Kmeans均衡相比,NNIC-Kmeans均衡的光正交频分复用系统误码率性能最好。
