Co-Sharing Waveform Design for Millimeter-Wave Radar Communication Systems

Millimeter-wave(mmWave)radar communication has emerged as an important technique for future wireless systems.However,the interference between the radar signal and communication data is the main issue that should be considered for the joint radar communication system.In this paper,a co-sharing waveform(CSW)is proposed to achieve communication and radar sensing simultaneously.To eliminate the co-interference between the communication and sensing signal,signal splitting and processing methods for communication data demodulation and radar signal processing are given respectively.Simulation results show that the bit error rate(BER)of CSW is close to that of the pure communication waveform.Moreover,the proposed CSW can achieve better performance than the existing waveforms in terms of range and velocity estimation.

Cognitive J^(2)SAC:Joint Jamming,Sensing,and Communication Under Antagonistic Environment

Integrated sensing and communication(ISAC)is regarded as a recent advanced technology,which is expected to realize the dual functions of sensing and communication simultaneously in one system.Nevertheless,it still faces the challenges of the information security and transmission robustness caused by the openness of wireless channel,especially under antagonistic environment.Hence,this article develops a generalized framework,named cognitive joint jamming,sensing and communication(cognitive J2SAC),to empower the current sensing/communication/jamming system with a“brain”for realizing precise sensing,reliable communication and effective jamming under antagonistic environment.Three kinds of gains can be captured by cognitive J2SAC,including integrated gain,cooperative gain and cognitive gain.Moreover,we highlight the enabling mechanism among jamming,sensing,and communication,as well as illustrating several typical use cases of cognitive J2SAC.Furthermore,several key enabled technologies are analyzed and a typical sensing enhance integrated communication and jamming case study is discussed to verify the effectiveness of the proposed method.Last but not the least,the future directions are listed before concluding this article.Integrated sensing and communication(ISAC)is regarded as a recent advanced technology,which is expected to realize the dual functions of sensing and communication simultaneously in one system.Nevertheless,it still faces the challenges of the information security and transmission robustness caused by the openness of wireless channel,especially under antagonistic environment.Hence,this article develops a generalized framework,named cognitive joint jamming,sensing and communication(cognitive J2SAC),to empower the current sensing/communication/jamming system with a“brain”for realizing precise sensing,reliable communication and effective jamming under antagonistic environment.Three kinds of gains can be captured by cognitive J2SAC,including integrated gain,cooperative gain and cognitive gain.Moreover,we highlight the enabling mechanism among jamming,sensing,and communication,as well as illustrating several typical use cases of cognitive J2SAC.Furthermore,several key enabled technologies are analyzed and a typical sensing enhance integrated communication and jamming case study is discussed to verify the effectiveness of the proposed method.Last but not the least,the future directions are listed before concluding this article.

A Brief Introduction on Joint Radar and Communication Systems

Joint radar and communication(JRC)technology is gradually becoming an essential approach to alleviating spectral congestion.Radar and communications systems were designed with common spectral and hardware resources to reduce size,improve performance,reduce cost,and decongest the spectrum.Various approaches have been proposed to achieve the coexistence of radar and communication systems.This paper mainly focuses on the research directions of radar communication coexistence(RCC)and dual-function radar communication systems(DFRC)in JRC technology.We summarize and analyze the existing research problems in the JRC era.According to the characteristics and advantages of JRC technology,we highlight several potentials in military and commercial applications.

Joint Radar and Communication: A Survey

Joint radar and communication(JRC)technology has become important for civil and military applications for decades.This paper introduces the concepts,characteristics and advantages of JRC technology,presenting the typical applications that have benefited from JRC technology currently and in the future.This paper explores the state-of-the-art of JRC in the levels of coexistence,cooperation,co-design and collaboration.Compared to previous surveys,this paper reviews the entire trends that drive the development of radar sensing and wireless communication using JRC.Specifically,we explore an open research issue on radar and communication operating with mutual benefits based on collaboration,which represents the fourth stage of JRC evolution.This paper provides useful perspectives for future researches of JRC technology.

Towards Converged Millimeter-Wave/Terahertz Wireless Communication and Radar Sensing

Converged communication and radar sensing systems have attained increasing attention in recent years.The development of converged radar-data systems is reviewed,with a special focus on millimeter/terahertz systems as a promising trend.Firstly,we present historical development and convergence technology concept for communication-radar systems,and highlight some emerging technologies in this area.We then provide an updated and comprehensive survey of several converged systems operating in different microwave and millimeter frequency bands,by providing some selective typical communication and radar sensing systems.In this part,we also summarize and compare the system performance in terms of maximum range/range resolution for radar mode and Bit Error Rate(BER)/wireless distance for communication mode.In the last section,the convergence of millimeter/terahertz communication-radar system is concluded by analyzing the prospect of millimeter-wave/terahertz technologies in providing ultrafast data rates and high resolution for our smart future.

Dual-Use Signal Design for Radar and Communication via Joint Orthogonal Signal and Phase Modulation

This paper proposes a new information modulation resorting to orthogonal signal and its phase for dual-function radar communication(DFRC)systems.Focusing on the standardized linear frequency modulation(LFM)signal by additional phase,a bank of signals enjoying satisfactory autocorrelation and cross-correlation characteristics,are generated.Then,these signals map the different information as well as their phases are also modulated to increase the communication bit rate,thus yielding a series of dual-use signals.Finally,the radar detection and communication performance of dual-use signals are also provided through numerical simulation and half-physical platform verification,confirming the effectiveness of the designed signals compared with the existing design strategy.

Joint Modulations of Electromagnetic Waves and Digital Signals on a Single Metasurface Platform to Reach Programmable Wireless Communications

In current wireless communication and electronic systems,digital signals and electromagnetic(EM)radiation are processed by different modules.Here,we propose a mechanism to fuse the modulation of digital signals and the manipulation of EM radiation on a single programmable metasurface(PM).The PM consists of massive subwavelength-scale digital coding elements.A set of digital states of all elements forms simultaneous digital information roles for modulation and the wave-control sequence code of the PM.By designing digital coding sequences in the spatial and temporal domains,the digital information and farfield patterns of the PM can be programmed simultaneously and instantly in desired ways.For the experimental demonstration of the mechanism,we present a programmable wireless communication system.The same system can realize transmissions of digital information in single-channel modes with beamsteerable capability and multichannel modes with multiple independent information.The measured results show the excellent performance of the programmable system.This work provides excellent prospects for applications in fifth-or sixth-generation wireless communications and modern intelligent platforms for unmanned aircrafts and vehicles.

Joint Active and Passive Beamforming Design for Hybrid RIS-Aided Integrated Sensing and Communication

Integrated sensing and communication(ISAC) is considered an effective technique to solve spectrum congestion in the future. In this paper, we consider a hybrid reconfigurable intelligent surface(RIS)-assisted downlink ISAC system that simultaneously serves multiple single-antenna communication users and senses multiple targets. Hybrid RIS differs from fully passive RIS in that it is composed of both active and passive elements, with the active elements having the effect of amplifying the signal in addition to phase-shifting. We maximize the achievable sum rate of communication users by collaboratively improving the beamforming matrix at the dual function base station(DFBS) and the phase-shifting matrix of the hybrid RIS, subject to the transmit power constraint at the DFBS, the signal-to-interference-plus-noise-ratio(SINR) constraint of the radar echo signal and the RIS constraint are satisfied at the same time. The builtin RIS-assisted ISAC design problem model is significantly non-convex due to the fractional objective function of this optimization problem and the coupling of the optimization variables in the objective function and constraints. As a result, we provide an effective alternating optimization approach based on fractional programming(FP) with block coordinate descent(BCD)to solve the optimization variables. Results from simulations show that the hybrid RIS-assisted ISAC system outperforms the other benchmark solutions.

Channel estimation in integrated radar and communication systems with power amplifier distortion

To reduce the negative impact of the power amplifier(PA)nonlinear distortion caused by the orthogonal frequency division multiplexing(OFDM)waveform with high peak-to-average power ratio(PAPR)in integrated radar and communication(RadCom)systems is studied,the channel estimation in passive sensing scenarios.Adaptive channel estimation methods are proposed based on different pilot patterns,considering nonlinear distortion and channel sparsity.The proposed methods achieve sparse channel results by manipulating the least squares(LS)frequency-domain channel estimation results to preserve the most significant taps.The decision-aided method is used to optimize the sparse channel results to reduce the effect of nonlinear distortion.Numerical results show that the channel estimation performance of the proposed methods is better than that of the conventional methods under different pilot patterns.In addition,the bit error rate performance in communication and passive radar detection performance show that the proposed methods have good comprehensive performance.

一种幅相联合调制雷达波形设计与处理方法

随着脉内特征识别、信号分选等电子侦察技术的发展,雷达波形设计正面临严峻的挑战。幅度调制作为一种新型脉冲调制方式,能够增加信号时域的复杂性,提升波形的反识别能力。本文提出一种幅相联合编码雷达波形,通过幅度相位联合调制提升雷达波形的复杂度,具有良好的反侦察潜力;利用幅度上的稀疏采样特点,提出匹配滤波与压缩感知相结合的回波信号处理方法处理此信号,有效提升低信噪比条件下的检测概率。最后通过仿真实验证明了所提幅相联合调制雷达波形设计与处理方法的有效性。

地基遥感联合反演大气边界层高度与ERA5再分析资料比对分析

利用北京国家综合气象探测试验基地超大城市观测试验建设的地基垂直遥感设备(激光气溶胶雷达、微波辐射计及风廓线雷达),使用2021年5—8月的观测资料,根据不同设备的探测优势以及边界层的日变化规律,利用激光气溶胶雷达、微波辐射计、风廓线雷达观测资料进行联合反演,得到全天候大气边界层高度。并将联合反演所得的边界层高度与探空资料计算及ERA5再分析资料提供的全天候大气边界层高度进行比较,发现:联合反演边界层高度与ERA5数据提供的大气边界层高度有较好的一致性;激光气溶胶雷达适用于白天对流边界层的观测,微波辐射计适用于夜间稳定边界层的观测,使用微波辐射计与风廓线雷达联合反演大气边界层高度可以改善弱降雨时单设备的反演结果;联合反演的大气边界层高度结果与单设备反演大气边界层高度均符合大气边界层的日变化规律;得到的联合反演边界层高度与探空数据计算得到的大气边界层高度差值的标准偏差为62 m,相较于ERA5数据提供的一定范围内大气边界层高度均值,联合反演边界层高度能更精准地反映更小范围内的大气边界层高度。

多天线正交频分复用的雷达信号处理算法

在实现雷达通信一体化中,正交频分复用信号被广泛使用,多输入多输出天线阵列的引入能定位目标所在的方位角,同时利用多天线也能提高通信的性能。在多输入多输出正交频分复用雷达通信一体化系统中,本文通过构建信号的雷达接收模型,将参数估计问题建模为压缩感知问题并进行求解,提出基于快速迭代收缩阈值算法的参数估计方法。仿真结果显示,在低信噪比情况下,本文所提方法优于基于迭代收缩阈值算法和基于正交匹配追踪的参数估计方法。

基于多通道联合稀疏重建的全极化SAR成像

全极化合成孔径雷达(SAR)可对不同极化通道分别独立进行压缩感知(CS)稀疏重建来增强成像性能,但分别独立处理没有利用极化信息的冗余性与互补性,有可能破坏极化信息的完整性。依据雷达目标在全极化下的散射特性构建联合稀疏度量函数,将全极化SAR高分辨成像转化为多通道联合稀疏约束的最优化重建问题,并用改进的正交匹配追踪算法进行求解。由于有效利用全极化信息,多通道联合CS成像相比于单通道CS成像能够获得更好的成像质量,还能全面准确反映目标全极化散射特性。通过对Backhoe挖掘机电磁仿真数据的处理,验证了算法的有效性,并且在微波暗室搭建了全极化SAR半实物仿真系统,利用其获取的全极化实测数据进一步验证了该方法的工程可行性。

基于DCS的统计MIMO雷达信号模型及参数估计

分布式压缩感知(Distributed Compressed Sensing,DCS)将单信号的压缩采样扩展到信号群的压缩采样,利用信号内相关性和互相关性对多个信号进行联合重构。统计多输入多输出(Multiple-Input Multiple-Output,MIMO)雷达系统通过多发多收配置,在发射机、目标以及接收机之间构成对目标的分布式探测系统。该文将DCS应用到统计MIMO雷达中,通过对该场景中目标回波的延时在距离空间稀疏性的分析,提出联合所有接收信号重构目标场景的设想,建立了接收信号的联合稀疏模型,并实现了目标参数估计的联合重构算法。仿真结果表明与基于压缩感知(Compressed Sensing,CS)的算法相比,基于DCS的算法在进一步降低采样数目的同时提高了参数估计精度,同时也验证了DCS-MIMO雷达可以有效克服目标的雷达散射截面积(Radar Cross Section,RCS)起伏。

二维压缩感知多投影矩阵特征融合的SAR目标识别方法

针对合成孔径雷达(synthetic aperture radar,SAR)目标识别问题,提出联合多层次二维压缩感知投影特征的方法。采用二维压缩感知投影作为基础特征提取算法,具有不依赖训练样本、效率高等显著优势。构建多个二维压缩感知投影矩阵提取原始SAR图像的多层次特征。不同投影矩阵获得的特征具有差异性,从不同方面描述SAR图像的灰度分布特性;同时,这些特征源自相同的输入图像,因此也具有一定的内在关联性。采用联合稀疏表示对提取的多个特征矢量进行表征分析,在内在关联性约束下考察不同特征的独立鉴别能力,从而提升每一类特征的稀疏表示精度。最终,根据求解的稀疏表示系数,分别在各个训练类别上对测试样本的多类特征进行重构,获得重构误差。根据最小误差的准则,判定测试样本所属目标类别。通过综合运用多层次二维压缩感知特征提取和联合稀疏表示分类,提高SAR目标识别的整体性能。利用MSTAR数据集中的多类目标SAR图像对方法进行测试验证,结果反映其在标准操作条件(standard operating condition,SOC)和扩展操作条件(extended operating condition,EOC)均可保持可靠的识别性能。

基于失配处理的OFDM雷达通信一体化共享信号旁瓣抑制技术

现代电子信息系统的应用领域在不断拓展,导致雷达和通信的带宽需求日益增长、工作频段不断重合,引发了电磁频谱竞争激烈、电磁干扰严重和电磁资源利用率低下等诸多问题。鉴于此,国内外专家学者提出了雷达通信一体化共享信号的解决思路。其中,OFDM信号被视为最有潜力的一体化共享信号。然而,受通信信息的高随机性和OFDM帧结构的周期性影响,该信号的雷达点扩展函数旁瓣较高,且存在大量伪峰。为此,本文围绕OFDM雷达通信一体化共享信号,从模糊函数的角度剖析了该信号的本质缺陷,并提出了一种利用失配滤波将旁瓣和伪峰外推至雷达观测窗口外的处理算法。通过理论分析和仿真可知,该算法可使OFDM一体化共享信号兼备高速通信和高性能雷达探测性能。

CS与GPR联合反演目标成像

压缩传感(CS)理论是在已知信号具有稀疏性或可压缩性的条件下对信号数据进行采集、编解码的新理论。压缩传感采用非自适应线性投影来保持信号的原始结构,能通过数值最优化问题准确重构原始信号。压缩传感以远低于奈奎斯特频率进行采样,在高分辨压缩成像系统、视频图像采集系统、雷达成像以及MRI医疗成像等领域有着广阔的应用前景。阐述了压缩传感理论框架以及信号稀疏表示、CS编解码模型,并进行了压缩传感与探地雷达联合反演目标成像。反演结果表明,随机孔径压缩传感成像算法比递归反向投影算法和最小二乘法所需数据量少,成像效果好,目标旁瓣小,对噪声的鲁棒性更好。

基于一体化波形的W波段光子辅助通信感知系统

提出并演示了一个光子辅助的集成雷达和通信系统,该系统利用光子辅助拍频在W波段产生毫米波信号。通过将正交相移键控(QPSK)信号编码到线性调频连续波(LFMCW)雷达信号上,实现了传感和通信波形的集成。一体化波形可以通过去啁啾分离通信信号与雷达感知信号,并通过脉冲压缩实现高分辨率感知。实验结果表明,在91 GHz频段内可实现单目标和双目标检测,感知精度约为2.0 cm。此外,成功实现了W波段下2 m、10 m和50 m传输距离的20 Gbit/s高质量无线通信。该系统还适用于各种成分的一体化波形,为高速通信和高分辨率雷达感知融合提供了有效参考。

基于FMCW的新型多域联合调制双功能雷达通信技术

在频谱稀缺现状与6G万物互联需求形势之下,雷达通信一体化得以催生,引起了学术界广泛的关注和研究兴趣.一体化的相关技术研究中,如何在有限的硬件资源条件下平衡好通信与感知性能是一个难题.为解决这个问题,本文提出了一种基于多域联合传输的通感一体化系统方案,利用空域、频域、时域和能量域4种资源进行信息传输,可有效提高数据传输准确率,提升系统性能.构建的自适应偏移索引调频连续波雷达通信系统(offset FMCW-based radar-communications system,OFRaC),有效挖掘了偏移索引调制与原调频连续波雷达通信系统(FMCW-based radar-communications system,FRaC)的优势特性,减少了射频切换时间,提升了传输速率.为降低通信接收端的误比特率(bit error rate,BER),文中还提出了一种基于最短信道距离的天线选择OFRaC(antenna selection-based OFRaC,AOFRaC),可以在OFRaC基础上对BER性能做进一步改善.最后,通过仿真实验,本文分析了AOFRaC,OFRaC与原FRaC系统在通信和感知方面的性能变化,对比了所使用目标检测方法与传统方法的性能优点.得出的结论是,所提出的多域联合调制方案在通信与感知性能中能取得更好的折中与平衡,尤其在需要更轻负载的车联网、无人机等应用场景中,简易的雷达和通信接收端架构将给系统带来优势.

基于分布式压缩感知的联合检测与跟踪算法

多基雷达系统对隐身目标的检测与跟踪具有良好的效果,但是在集中式融合框架下应用于多基雷达的检测与跟踪算法具有计算复杂、计算量大的缺点.对此,提出一种应用于多基雷达系统的基于分布式压缩感知的联合检测与跟踪算法.首先,应用分布式紧凑感知矩阵追踪算法直接重构出表征目标状态空间信息的稀疏网格反射向量;然后,应用检测前跟踪算法得到精确的目标运动状态和轨迹.仿真实验表明了所提出算法的有效性.