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.

Optimization and Performance Enhancement of Gesture Recognition Algorithm Based on FMCW Millimeter-Wave Radar

Gesture recognition plays an increasingly important role as the requirements of intelligent systems for human-computer interaction methods increase.To improve the accuracy of the millimeter-wave radar gesture detection algorithm with limited computational resources,this study improves the detection performance in terms of optimized features and interference filtering.The accuracy of the algorithm is improved by refining the combination of gesture features using a self-constructed dataset,and biometric filtering is introduced to reduce the interference of inanimate object motion.Finally,experiments demonstrate the effectiveness of the proposed algorithm in both mitigating interference from inanimate objects and accurately recognizing gestures.Results show a notable 93.29%average reduction in false detections achieved through the integration of biometric filtering into the algorithm’s interpretation of target movements.Additionally,the algorithm adeptly identifies the six gestures with an average accuracy of 96.84%on embedded systems.

Automatic Identification of Clear-Air Echoes Based on Millimeter-wave Cloud Radar Measurements

Millimeter-wave cloud radar(MMCR)provides the capability of detecting the features of micro particles inside clouds and describing the internal microphysical structure of the clouds.Therefore,MMCR has been widely applied in cloud observations.However,due to the influence of non-meteorological factors such as insects,the cloud observations are often contaminated by non-meteorological echoes in the clear air,known as clear-air echoes.It is of great significance to automatically identify the clear-air echoes in order to extract effective meteorological information from the complex weather background.The characteristics of clear-air echoes are studied here by combining data from four devices:an MMCR,a laser-ceilometer,an L-band radiosonde,and an all-sky camera.In addition,a new algorithm,which includes feature extraction,feature selection,and classification,is proposed to achieve the automatic identification of clear-air echoes.The results show that the recognition algorithm is fairly satisfied in both simple and complex weather conditions.The recognition accuracy can reach up to 95.86%for the simple cases when cloud echoes and clear-air echoes are separate,and 88.38%for the complicated cases when low cloud echoes and clear-air echoes are mixed.

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.

Millimeter-wave LFMCW radar water surface detection experiment and its imaging algorithm

A millimeter-wave linear frequency modulated continuous wave(LFM CW)radar is applied to water surface detection.This paper presents the experiment and imaging algorithm.In imaging processing,water surface texture can hardly be seen in the results obtained by traditional imaging algorithm.To solve this problem,we propose a millimeter-wave LFMCW radar imaging algorithm for water surface texture.Different from the traditional imaging algorithm,the proposed imaging algorithm includes two improvements as follows:Firstly,the interference from static targets is removed through a frequency domainfilter;Secondly,the multiplicative noises are reduced by the maximum likelihood estimation method,which is used to estimatethe azimuth spectrum parameters to calculate the energy of water surface echo.Final results show that the proposed algorithmcan obtain water surface texture,which means that the proposed algorithm is superior to the traditional imaging algorithm.

Comparison of Liquid Water Content Retrievals for Airborne Millimeter-Wave Radar with Different Particle Parameter Schemes

In the application of the physical iterative method to retrieve millimeter-wave radar liquid water content(LWC)and liquid water path(LWP),particle parameter scheme is the main factor affecting retrieval performance.In this paper,synchronous measurements of an airborne millimeter-wave radar and a hot-wire probe in stratus cloud are used to compare the LWC retrievals of the oceanic and continental particle parameter scheme with diameter less than 50μm and the particle parameter scheme with diameter less than 500μm and 1500μm(scheme 1,scheme 2,scheme 3,and scheme4,respectively).The results show that the particle parameter scheme needs to be selected according to the reflectivity factor when using the physical iterative method to retrieve the LWC and LWP.When the reflectivity factor is less than-30 d BZ,the retrieval error of scheme 1 is the minimum.When the reflectivity factor is greater than-30 d BZ,the retrieval error of scheme 4 is the minimum.Based on the reflectance factor value,the LWP retrievals of scheme 4 are closer to the measurements,the average relative bias is 5.2%,and the minimum relative bias is 4.4%.Compared with other schemes,scheme 4 seems to be more useful for the LWC and LWP retrieval of stratus cloud in China.

Non-LOS target localization via millimeter-wave automotive radar

This paper considers the non-line-of-sight(NLOS)vehicle localization problem by using millimeter-wave(MMW)automotive radar.Several preliminary attempts for NLOS vehicle detection are carried out and achieve good results.Firstly,an electromagnetic(EM)wave NLOS multipath propagation model for vehicle scene is established.Subsequently,with the help of available multipath echoes,a complete NLOS vehicle localiza-tion algorithm is proposed.Finally,simulation and experimental results validate the effectiveness of the established EM wave propagation model and the proposed NLOS vehicle localization algorithm.

New method for passive radar seeker to antagonize non-coherent radar decoy

Using super resolution direction of arrival（DOA） estimation algorithm to reduce the resolution angle is an effective method for passive radar seeker（PRS） to antagonize non-coherent radar decoy.Considering the power and correlation property between radar and non-coherent decoy,an improved subspace DOA estimation method based on traditional subspace algorithm is proposed.Because this new method uses the invariance property of noise subspace,compared with traditional MUSIC algorithm,it shows not only better resolution in condition of closely spaced sources,but also superior performance in case of different power or partially correlated sources.Using this new method,PRS can distinguish radar and non-coherent decoy with good performance.Both the simulation result and the experimental data confirm the performance of the method.

The Echo Modelling and Simulation of the Semi-Active Radar Seeker against a Sea Skimming Target

This paper has proposed a new modelling and simulating technique for the echo of the semi-active radar seeker against the sea skimming target. The echo modelling is based on the electromagnetic scattering mechanisms. A modified Four-path model based on the radar detection scene is used to describe the multipath scattering between the target and rough sea surface. A Facet-based Small Slope Approximation (FBSSA) method is employed to calculate the scattering from the sea surface. The Physical Optics (PO) and the Equivalent Edge Current (EEC) Method is used to calculate the target scattering. In the echo simulations. The results present the original echo and the echo processed by the signal processing procedures, where the clutter and multipath effect can be observed.

Signal processing method of a novel polarized array radar seeker

This paper proposes a novel polarized radar seeker based on the polarized antenna array. A fully polarized signal processing method for the proposed radar seeker is studied under the environments with electromagnetic interferences. A dual polarized antenna array is employed to transmit and receive the radar signals. The instantaneous polarization signal processing technique is used to detect and recognize the targets. The direction of arrival （DOA） of the target is measured through the spatial spectrum with high resolution for the polarized array radar seeker system. The fully polarized signal model of the polarized array radar seeker is formulated and a specific signal processing algorithm is expounded. The theoretical research and numerical simulation results demonstrate that the proposed radar seeker has good performances in target detection and electronic warfare. The research results can provide an effective technical approach to develop and research the new generation radar seeker.

A Survey of Gesture Recognition Using Frequency Modulated Continuous Wave Radar

With technology advances and human requirements increasing, human-computer interaction plays an important role in our daily lives. Among these interactions, gesture-based recognition offers a natural and intuitive user experience that does not require physical contact and is becoming increasingly prevalent across various fields. Gesture recognition systems based on Frequency Modulated Continuous Wave (FMCW) millimeter-wave radar are receiving widespread attention due to their ability to operate without wearable sensors, their robustness to environmental factors, and the excellent penetrative ability of radar signals. This paper first reviews the current main gesture recognition applications. Subsequently, we introduce the system of gesture recognition based on FMCW radar and provide a general framework for gesture recognition, including gesture data acquisition, data preprocessing, and classification methods. We then discuss typical applications of gesture recognition systems and summarize the performance of these systems in terms of experimental environment, signal acquisition, signal processing, and classification methods. Specifically, we focus our study on four typical gesture recognition systems, including air-writing recognition, gesture command recognition, sign language recognition, and text input recognition. Finally, this paper addresses the challenges and unresolved problems in FMCW radar-based gesture recognition and provides insights into potential future research directions.

Multiscale Feature Fusion for Gesture Recognition Using Commodity Millimeter-Wave Radar

Gestures are one of the most natural and intuitive approach for human-computer interaction.Compared with traditional camera-based or wearable sensors-based solutions,gesture recognition using the millimeter wave radar has attracted growing attention for its characteristics of contact-free,privacy-preserving and less environmentdependence.Although there have been many recent studies on hand gesture recognition,the existing hand gesture recognition methods still have recognition accuracy and generalization ability shortcomings in shortrange applications.In this paper,we present a hand gesture recognition method named multiscale feature fusion(MSFF)to accurately identify micro hand gestures.In MSFF,not only the overall action recognition of the palm but also the subtle movements of the fingers are taken into account.Specifically,we adopt hand gesture multiangle Doppler-time and gesture trajectory range-angle map multi-feature fusion to comprehensively extract hand gesture features and fuse high-level deep neural networks to make it pay more attention to subtle finger movements.We evaluate the proposed method using data collected from 10 users and our proposed solution achieves an average recognition accuracy of 99.7%.Extensive experiments on a public mmWave gesture dataset demonstrate the superior effectiveness of the proposed system.

Single-pixel 3D imaging based on fusion temporal data of single-photon detector and millimeter-wave radar

Recently,there has been increased attention toward 3D imaging using single-pixel single-photon detection(also known as temporal data)due to its potential advantages in terms of cost and power efficiency.However,to eliminate the symmetry blur in the reconstructed images,a fixed background is required.This paper proposes a fusion-data-based 3D imaging method that utilizes a single-pixel single-photon detector and millimeter-wave radar to capture temporal histograms of a scene from multiple perspectives.Subsequently,the 3D information can be reconstructed from the one-dimensional fusion temporal data by using an artificial neural network.Both the simulation and experimental results demonstrate that our fusion method effectively eliminates symmetry blur and improves the quality of the reconstructed images.

Photonics-assisted joint radar jamming and secure communication in the millimeter-wave band based on CE-LFM-OFDM

This paper reports a photonics-assisted millimeter-wave (mm-wave) joint radar jamming and secure communication system constructed through a photonic upconversion technique. In the experiments, a 30 GHz constant envelope linear frequency-modulated orthogonal frequency division modulation(CE-LFM-OFDM) signal with an instantaneous bandwidth of 1 GHz is synthesized by encoding 1 GBaud encrypted 16-quadrature amplitude modulation(16-QAM) OFDM signal. The velocity deception jamming is achieved with a spurious suppression ratio over 30 dB. Furthermore, we efficiently execute range deception jamming with a time shift of 10 ns. Simultaneously, the encrypted 16-QAM OFDM signal is successfully transmitted over a 1.2 m wireless link, with a data rate of 4 Gbit/s.

A DETECTION METHOD OF HIGH RESOLUTION RADAR TARGETS BASED ON POSITION CORRELATION

This paper studies a detection method of targets of high resolution radar operating at the band of millimeter-wave(32-38GHz) under the background of the clutters, and proposes a new nonparametric detection method, which not only does less computation, but also is able to detect multiple extended targets radially distributed along distance "corridor", based on the position (range) correlation information of one-dimensional range images(or called range profiles) of high resolution radar targets. The experimental results, on the real echo data of tank illuminated by the millimeter-wave stepped frequency high resolution radar, have certified that such a method presented in this paper is a very effective detection method for multiple extended targets.

Vital Sign Signal Extraction Based on mmWave Radar

This research develops an algorithm for health monitoring and uses the Infineon BGT60TR13C shield 60GHz radar to build a set of software and hardware demonstration platforms for algorithm verification. The algorithm can monitor the position, breathing, heartbeat and other information of the elderly in real time, which is used to judge the health status of the elderly and improve the convenience for early warning and rescue of abnormal situations in time. However, limited by the transmission power of this radar and the number of transmitting and receiving antennas, the current detection range of the algorithm is relatively small, and the ability to distinguish between multiple persons is limited. This problem can be optimized by replacing other types of radars in the future.

基于空间网格划分的地杂波建模新方法

雷达型空空导弹具有全天候、全空域作战能力,具有较强的低空下视能力。在导弹下视攻击时,地面多普勒杂波会影响导引头对真实目标的检测。针对高重频脉冲多普勒雷达导引头,提出了一种基于空间网格划分建立地杂波模型的新方法,以天线波束指向为中心,围绕天线主瓣在三维空间划分网格,之后计算投影到地面的网格面积,根据雷达方程建立回波信号模型。通过理论推导,给出了影响地杂波强度的主要因素,包括导弹距地面高度、导引头波束擦地角和地面反射率等。最后通过建立数字仿真模型验证了方法的正确性。该方法可以在保证杂波形态一样的同时减少仿真时间。

大掠射角对海雷达导引头实测回波特性分析

大掠射角下,对海雷达导引头观测到的海杂波强度激增,舰船目标检测困难。本文结合全极化雷达导引头挂飞实测数据,分析了回波幅度和相位特性。首先,采用典型分布对回波幅度分布进行拟合,并利用拟合优度对拟合效果作出评估;然后,分析了平均相位变化量。结果表明:在大掠射角条件下,雷达导引头各极化通道海杂波幅度服从K分布;海杂波与舰船回波幅度在同极化通道服从K分布,在交叉极化通道服从对数正态分布;交叉极化通道回波信杂比高于同极化通道;海杂波与舰船回波相位平均变化量小于海杂波。

基于极化与距离像特征融合的雷达导引头角反射器鉴别方法

角反射器形成的强假目标干扰给反舰导弹雷达导引头目标识别带来了严峻的挑战。为提高反舰导弹雷达导引头抗冲淡式角反射器干扰能力,提出一种基于极化与高分辨距离像(high resolution range profile,HRRP)多特征融合的角反射器鉴别方法。结合3种场景下的实验数据,首先从海杂波中提取雷达导引头目标回波信号;其次,分析了角反和舰船回波的峰值个数、径向尺寸等5个距离像特征,以及极化相关系数均值等3个极化特征。实验数据处理结果表明,舰船与单个角反特征差异明显,与阵列角反特征差异减小;然后利用支持向量机(support vector machine,SVM)方法,基于实验数据设计5组测试,分别检验了单特征和多特征融合的鉴别性能。测试结果表明,单特征鉴别方法性能不稳定,而所提出的三特征融合鉴别方法更具稳健性,在5组测试中鉴别准确率均达到92.86%以上。

基于主被动复合导引头的干扰态势构建

在导引头主被动信息融合过程中,存在多装备与多目标平台关联困难、无法有效提取目标特征信息,难以有效融合构建态势的问题。因此,本文提出一种将导引头主动雷达信息和被动侦察信息融合的数据关联方法。该方法先提取导引头干扰态势表征要素,然后以目标方位为中心,将平台与装备关联,构建干扰态势。本文通过主被动信息融合构建的态势,在原先分离的平台和设备间建立空间位置与搭载的关系,可以有效地消除欺骗式干扰和多径散射假目标,提高态势认知效率。