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.

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.

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.

Design of integrated radar and communication system based on MIMO-OFDM waveform

Orthogonal frequency division multiplexing (OFDM) waveform enables radar and communication functions simultaneously, which encounters low angle resolution and poor data rate for traditional single input single output (SISO) systems. To solve these problems, an integrated radar and communication system (IRCS) with multiple input multiple output (MIMO) OFDM waveform is proposed. The different limitations of radar and communication in designing such a system are investigated. Then, an optimization problem is devised to obtain suitable system parameters, including the number of subcarriers, subcarrier spacing, number of symbols, pulse repetition frequency (PRF) and length of cyclic prefix (CP). Finally, to satisfy the requirements of both radar and communication, the IRCS parameters are derived in three typical cases. Several numerical results are presented to illustrate the demands of radar and communication, inconsistent or consistent, for the IRCS parameters and the superiority of the proposed system.

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.

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.

A robust joint frequency spectrum and power allocation strategy in a coexisting radar and communication system

The resource allocation technique is of great significance in achieving frequency spectrum coexistence in Joint Radar-Communication(JRC)systems,by which the problem of radio frequency spectrum congestion can be well alleviated.A Robust Joint Frequency Spectrum and Power Allocation(RJFSPA)strategy is proposed for the Coexisting Radar and Communication(CRC)system.Specifically,we consider the uncertainty of target Radar Cross Section(RCS)and communication channel gain to formulate a bi-objective optimization model.The joint probabilities that the Crame´r-Rao Lower Bound(CRLB)of each target satisfying the localization accuracy threshold and the Communication Data Ratio(CDR)of each user satisfying the communication threshold are simultaneously maximized,under the constraint of the total power budget.A Three-Stage Alternating Optimization Method(TSAOM)is proposed to obtain the Best-Known Pareto Subset(BKPS)of this problem,where the frequency spectrum,radar power,and communicator power are allocated using the greedy search and standard convex optimization methods,respectively.Simulation results confirm the effectiveness of the proposed RJFSPA strategy,compared with the resource allocation methods in a uniform manner and that ignores the uncertainties.The efficiency of the TSAOM is also verified by the comparison with the exhaustive search-based method.

Target parameter estimation for OTFS-integrated radar and communications based on sparse reconstruction preprocessing

Orthogonal time-frequency space(OTFS)is a new modulation technique proposed in recent years for high Doppler wireless scenes.To solve the parameter estimation problem of the OTFS-integrated radar and communications system,we propose a parameter estimation method based on sparse reconstruction preprocessing to reduce the computational effort of the traditional weighted subspace fitting(WSF)algorithm.First,an OTFS-integrated echo signal model is constructed.Then,the echo signal is transformed to the time domain to separate the target angle from the range,and the range and angle of the detected target are coarsely estimated by using the sparse reconstruction algorithm.Finally,the WSF algorithm is used to refine the search with the coarse estimate at the center to obtain an accurate estimate.The simulations demonstrate the effectiveness and superiority of the proposed parameterestimation algorithm.

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.

Statistical Investigation and Mapping of Monthly Modified Refractivity Gradient over Pakistan at the 700 Hectopascal Level

This study is an effort to investigate the spatial-temporal variability of the modified refractivity gradient at the 700 hPa pressure level over Pakistan and its neighbouring regions of Afghanistan, India, Iran and the Arabian Sea using the remote sensing data of the AQUA (AIRX3STM) satellite from 2008 to 2012. Trapping conditions only found in December were spread over Khyber Pakhtunkhwa (Gilgit-Baltistan, Pakistan) with an average value of -182.042 M/Km and showing Leptokurtic distributions. The lowest monthly average value super-refractive conditions existed in the autumn season with a strong monthly correlation (>0.91 M/Km). A very high monthly correlation (0.9 M/Km) was found for the super-refractive conditions over the whole time period. The largest spatial and temporal normal conditions appeared in January with the average value for normal conditions being 132.72 M/Km (found over Zabul, Afghanistan) with Leptokurtic distributions. During May normal conditions were the smallest in spatial extent over Pakistan, India and Afghanistan, showing Platykurtic distributions. Sub-refractive conditions mostly prevailed at all times. The probability for extreme sub-refractive conditions was very high in 2008-2012. The highest average sub-refractive conditions appeared in the winter and autumn seasons (spread around Quetta and Kalam, Pakistan). The highest monthly average sub-refractive conditions with a value of 1,265,188 M/Km were found in January and spread around the Sarbaz River Iran. Correlations for the existence of sub-refractive conditions varied from 0.8 M/Km (moderate strong) to 0.4 M/Km during the autumn to winter season. Permanent super-refractive conditions existed over Baluchistan from February to September.