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Femtocell access point gives an efficient solution to furnish peak data rates in indoor wireless access systems. Propagation of the signal will get up-shot because of few considerations in advanced communication appliances. The maximum simulation reflection coefficient ( S 11 ) of proposed antenna is 45.12 dB, directivity is 6.54 dBi with the efficiency of 60% and at 60 GHz, and the measurement value of 36.35 is observed which covers the complete RADAR applications which have an unlicensed bandwidth. The proposed tree-shaped unequal slotted antenna is well suited for millimeter-wave applications because of its good bandwidth and less dimension.

Electronic beam steering is an essential feature of state-of-the-art radar systems. Conventional phased array (PA) radars with fixed carrier frequencies are well-known for electronically steering their beam with high directivity. However, the resulting beampattern is angle-dependent but range-independent. Recently, a new electronic beam steering concept, referred to as frequency diverse array (FDA) radar, has attracted increasing attention due to its unique range-angle dependent beampattern. More importantly, the FDA radar employs a small frequency increment across the array elements to achieve beam steering as a function of angle, range, and time. In this paper, we review the development of the FDA radar since its inception in 2006. Since the frequency offset attaches great importance in FDAs to determine the beampattern shape, initially much of the research and development were focused on designing the optimal frequency offsets for improved beampattern synthesis. Specifically, we analyze characteristics of the FDA beampattern synthesis using various frequency offsets. In addition to analyzing the FDA beampattern characteristics, this study also focuses on the neglected propagation process of the transmitted signals in the early FDA literature, and discuss the time-variant perspective of FDA beampatterns. Furthermore, FDA can also play a significant role in wireless communications, owing to its potential advantages over the conventional PAs. Therefore, we highlight its potential applications in wireless communication systems. Numerical simulations are implemented to illustrate the FDA beampattern characteristics with various frequency offset functions.

An ultra-wideband chaotic radar with wireless synchronization command is proposed and experimentally demonstrated for target localization and tracking. This radar uses the wideband chaotic pulse position modulation (CPPM) signal as the probe signal and the radar structure of single-transmitting-dual-receiving. The echo signal scattered from a target is collected by two receivers. The target is located and tracked accurately in two-dimensional space using the signal processing scheme. In particular, the radar receivers can directly generate the CPPM reference signals through a wireless synchronization command, so that the transceivers can be physically separated without cable or optical fiber connection. Experimental results demonstrate the proposed chaotic radar can locate and track the target accurately. A localization error of 11 cm and a detection resolution of 17 cm can be both achieved. Moreover, this radar possesses the excellent immune performance to the external electromagnetic interferences, which makes it suitable in the complex electromagnetic environment caused by the cooperative work of multiple radars.

Coexisting radar and communication (CRC) systems on the same spectrum band have been recently recognized as a promising approach to solve the spectrum scarcity problem. Additionally, with the new requirements of achieving higher energy efficiency and restoring the consumed power, an initiative has been exploited to embed both information and energy within the same signal. Motivated by that, this paper presents a unified model to implement the concept of simultaneous wireless information and power transfer (SWIPT) in the coexistence environment between radar and communication systems. Specifically, we propose a novel energy harvesting based CRC model (CRCEH), in which the signals transmitted from both the communication and radar transmitters are precoded towards their conventional targets, communication receiver and radar targets respectively, as well as to an energy harvesting receiver. This system is capable of solving the spectrum scarcity problem as well as supporting low power devices with their energy requirements from the energy harvested at the energy harvesting receiver. The design problem is formulated as maximizing the radar detection probability subject to communication capacity and energy harvesting constraints. However, directly processing the data from the radar receiver requires high computational complexity and hardware costs. In order to circumvent this issue, this paper also proposes to deploy lens antenna array (LNA) to CRCEH system to sharply direct the signals to the energy harvesting receiver together with their respective destinations. Since LNA is able to focus the signal power on a subset of antennas, we may only deal with the data from the selective antenna subset associated with the maximal power. Numerical results show that the proposed method is able to achieve improved performance in terms of radar detection under communication capacity constraints compared to the conventional approaches besides the great benefit of harvesting the energy to feed some limited energy devices.

In this article, we study the joint communication and sensing (JCAS) paradigm in the context of millimeter-wave (mm-wave) mobile communication networks. We specifically address the JCAS challenges stemming from the full-duplex operation and from the co-existence of multiple simultaneous beams for communications and sensing purposes. To this end, we first formulate and solve beamforming optimization problems for hybrid beamforming based multiuser multiple-input and multiple-output JCAS systems. The cost function to be maximized is the beamformed power at the sensing direction while constraining the beamformed power at the communications directions, suppressing interuser interference and cancelling full-duplexing related self-interference (SI). We then also propose new transmitter and receiver beamforming solutions for purely analog beamforming based JCAS systems that maximize the beamforming gain at the sensing direction while controlling the beamformed power at the communications direction(s), cancelling the SI as well as eliminating the potential reflection from the communication direction and optimizing the combined radar pattern (CRP). Both closed-form and numerical optimization based formulations are provided. We analyze and evaluate the performance through extensive simulations, and show that substantial gains and benefits in terms of radar transmit gain, CRP, and SI suppression can be achieved with the proposed beamforming methods.

In this paper, we propose a deep learning-based indoor two-dimensional (2D) localization scheme using a 24 GHz frequency-modulated continuous wave (FMCW) radar. In the proposed scheme, deep neural network and convolutional neural network (CNN) models that use different numbers of FMCW radars were employed to overcome the limitations of the conventional 2D localization scheme that is based on multilateration methods. The performance of the proposed scheme was evaluated experimentally and compared with the conventional scheme under the same conditions. According to the results, the 2D location of the target could be estimated with a proposed single radar scheme, whereas two FMCW radars were required by the conventional scheme. Furthermore, the proposed CNN scheme with two FMCW radars produced an average localization error of 0.23 m, while the error of the conventional scheme with two FMCW radars was 0.53 m.

In recent years, there have been plenty of demands and growth in the autonomous vehicle industry, and thus, challenges of designing highly efficient photonic radars that can detect and range any target with the resolution of a few centimeters have been encountered. The existing radar technology is unable to meet such requirements due to limitations on available bandwidth. Another issue is to consider strong attenuation while working under diverse atmospheric conditions at higher frequencies. The proposed model of photonic radar is developed considering these requirements and challenges using the frequency-modulated direct detection technique and considering a free-space range of 750 m. The result depicts improved range detection in terms of received power and an acceptable signal-to-noise ratio and range under adverse climatic situations.

The demand for dual-functional wireless systems is on the rise as certain resources become more congested and scarce. Joint communication-radar (JCR) is a promising technology that is becoming very critical and growing in popularity, where communication and radar applications are serviced simultaneously sharing the same hardware/software and the frequency band resources. JCR and its alternatives need to be cleverly integrated into certain waveforms such as orthogonal frequency division multiplexing (OFDM) to function properly without degradation in the performance. With the aid of the promising concepts of index modulation (IM) and Golay complementary sequences, a novel JCR waveform is proposed to serve both communication and radar applications with the same resources. It has been shown by extensive computer simulations that the proposed OFDM with an index modulation (OFDM-IM) waveform outperforms the classical OFDM with fixed pilot design both in bit error rate (BER) performance and radar-based applications by introducing diversity among subcarriers and frequency agility over the whole frequency band.

This paper provides an overview of the most recent passive radars based on long-term evolution (LTE). To begin, this paper investigates the various characteristics and requirements of 4 G LTE signals for radar, taking performance aspects such as range, velocity, range resolution, and velocity resolution into account. An ambiguity function analysis is performed on a measured LTE signal using the synchronization and reference signal components to evaluate key performance parameters such as Doppler and range characteristics. We also discuss how LTE passive radar can be used in a variety of applications. The detailed analysis of the LTE downlink signal, its structural overview, and the effect on cross- and self-ambiguity functions are all discussed. The paper investigates related standard development proposals, with a focus on performance evaluation criteria for existing passive radar technologies. As a result, this survey paper serves as a starting point for evaluating the performance of current and future passive radar innovations, including an emerging 5 G radar.

In recent years, multiple functions traditionally realized by hardware components have been replaced by digital-signal processing, making radar and wireless communication technologies more similar. A joint radar and communication system, referred to as a RadCom system, was proposed to overcome the drawbacks of the conventional existent radar techniques while using the same system for intervehicular communication. Consequently, this system enhances used spectral resources. Conventional orthogonal frequency division multiplexing (OFDM) was proposed as a RadCom waveform. However, due to OFDM’s multiple shortcomings, we propose universal filtered multicarrier (UFMC), a new 5G waveform candidate, as a RadCom waveform that offers a good trade-off between performance and complexity. In addition to that, we propose multicarrier code division multiple access (MC-CDMA) as a multiple-access (MA) technique that can offer great performance in terms of multiuser detection and power efficiency. Moreover, we study how UFMC filter length and MC-CDMA spreading sequences can impact overall performance on both radar and communication separately under a multipath channel. Analysis of the bit error rate (BER) of the UFMC waveform was performed in order to confirm the experiment results.

International audience; In this article, we demonstrate the use of general software-defined radio (SDR) hardware for ground-based interferometric radar (GBIR) system development for static target imaging and displacement estimation purposes. First, a system synchronization approach is proposed within the free and open-source framework GNU Radio, followed by a frequency-domain bandwidth synthesis method used to improve the range resolution with three different waveforms. Second, data preprocessing and target imaging methods are proposed to reduce the negative influences of practical nonideal factors and get high-quality target images. Finally, various experiments are conducted to show the performance of the developed SDR-GBIR system and the proposed methods. It is shown that high-resolution target image and high-accuracy displacement measurement can be obtained by our SDR-GBIR systems.

This paper deals with the problem of modeling and detecting extended targets using distributed coherent multi-band multiple-input multiple-output radars enabled by photonics. First, a well-established methodology is applied for modeling the radar cross-section (RCS) of a sample maritime target. Then, the target RCS behavior is studied varying the aspect angle and operating frequency. Finally, different detection strategies, based on the constant false alarm rate criterion, are investigated and compared. Simulations are performed to evaluate the performance of the proposed strategies in close-to-reality maritime surveillance scenarios. The decisive impact of distributed sensors and multiple carrier frequencies is demonstrated compared to a single-band stand-alone radar system.

Autonomous vehicles are regarded as future transport mechanisms that drive the vehicles without the need of drivers. The photonic-based radar technology is a promising candidate for delivering attractive applications to autonomous vehicles such as self-parking assistance, navigation, recognition of traffic environment, etc. Alternatively, microwave radars are not able to meet the demand of next-generation autonomous vehicles due to its limited bandwidth availability. Moreover, the performance of microwave radars is limited by atmospheric fluctuation which causes severe attenuation at higher frequencies. In this work, we have developed coherent-based frequency-modulated photonic radar to detect target locations with longer distance. Furthermore, the performance of the proposed photonic radar is investigated under the impact of various atmospheric weather conditions, particularly fog and rain. The reported results show the achievement of significant signal to noise ratio (SNR) and received power of reflected echoes from the target for the proposed photonic radar under the influence of bad weather conditions. Moreover, a conventional radar is designed to establish the effectiveness of the proposed photonic radar by considering similar parameters such as frequency and sweep time.

Wireless sensing based on radar devices is used today in various environments to ensure sustainability and protection of natural resources, to save time and energy in industry and agriculture, and in many other applications. Development of radar technology, in particular in millimeter-wave frequency bands, has opened many new applications which are being currently developed. Important aspect of these systems is increased level of system autonomy based on the principles of machine learning or artificial intelligence. In order to exploit these advantages, we need to acquire as much as possible measured information which can be used later in various detection scenarios. Our aim is to perform a polarization sensitivity analysis for a simple S-band FMCW radar system. The acquired measured results demonstrate the differences when scanning the polarization and give us a indication on how this can be exploited in future systems with polarization diversity.

This paper proposes a superposition transmission scheme for the future Radio Frequency (RF) convergence applications. The scheme is discussed under the assumption of a monostatic broadcasting channel topology. Under communications quality-of-service (QoS) constraints, the joint performance region of communications sum rate and radar estimation error variance is studied. Two radar signal waveforms, namely linear FM and parabolic FM, are used to investigate how signal shapes may influence the estimation accuracy. Both waveforms are generated with rectangular envelope. In the end, a numerical analysis is applied, which concludes that a moderate communications QoS promises a good communications fairness while with the limited radar performance degradation. acceptedVersion

This work reports the first realization of a combined radar&lidar system based on silicon-on-insulator photonic integrated circuit (PIC). The software-defined architecture comprises a frequency-flexible and simultaneous multi-band radar operation and an advanced lidar with coherent detection for range and velocity measurements. Both systems are implemented within a single chip, allowing a coherent radar and lidar parallel data acquisition in order to take advantage of their complementary characteristics. This feature potentializes the study of complex environments providing a more complete cognition of the target or scene under observation. Here, we present the first sets of results of the radar and lidar subsystems characterization without any auxiliary frontend that confirms the large frequency flexibility of the radar system and the great potentiality for high resolution range and velocity measurements of the lidar system. These results open the way to an innovative generation of transceivers in the field of microwave photonics, potentially outperforming current systems thanks to its multiband and multifunction capability owing to a unique hybrid radar&lidar coherent architecture. Moreover, by operating in the photonic domain, radar and lidar subsystems are able to share the same optical source and digital electronics unit, allowing for an ultimate reduction of size, weight, and power consumption, thus making the proposed architecture suitable for the most stringent applications.

The in-band full-duplex (IBFD) wirelesscommunication can achieve not only appreciable throughputgain but also is a key technology to enable concurrent radar andcommunication by one hardware. In such a system, an analogself-interference (SI) canceller is essential so that the receivedsignal can be processed digitally to achieve sufficient SNRfor IBFD communication. Unlike the previous similar workswhich rely on a classical matched filter, this paper derives therange-Doppler profile from the state of an adaptive filter, whichprimarily is applied to cancel the residual SI. Using standardIEEE 802.11ac signal, the proposed waveform-independenttechnique in this paper is simulated in a multi-target IBFDscenario. Furthermore, we employed a proof of concept setup tovalidate the proposed approach. The simulation and experimentalresults confirm that our method can render accurate rangeand velocity detection, and potentially satisfies a wide spectrumof opportunistic wireless sensing applications, ranging fromhand/body gesture detection to tracking and localization., info:eu-repo/semantics/published

This paper presents an analysis of a new method of automotive radar self-calibration which uses targets of opportunity. While conventional offline calibration of a phased array antenna requires accurate knowledge of the positions of calibration targets relative to the radar, such information is not available in a dynamic scenario. To compensate for this, we have developed an estimation procedure based on an extended Kalman filter (EKF) to address the challenge of simultaneous localisation, mapping and calibration. The proposed technique makes it possible to compensate for moderate errors of amplitude and phase in the phased array response with just a few measured frames. A significant reduction in the sidelobe rejection of the array response, plus the ability to correct for angular steering errors, are demonstrated via numerical simulations and real data processing.

En las últimas décadas los sistemas avanzados de asistencia al conductor (ADAS) han evolucionado hasta estar disponibles en gran parte de los vehículos fabricados hoy en día; mantener actualizada la enseñanza en esta área es de vital importancia. Este artículo presenta un radar de onda continua modulado en frecuencia que trabaja en la banda de 24 GHz ISM. El propósito es evaluar su desempeño e idoneidad para usarse como herramienta didáctica en la enseñanza en las carreras de Ingeniería Automotriz y de Telecomunicaciones con énfasis en las asignaturas de Matemáticas y Telecomunicaciones con escenarios factibles de encontrar en los laboratorios universitarios. Para ello se describe el escenario de medición, así como el hardware, el firmware y un algoritmo genérico implementado en MATLAB basado en transformadas rápidas de Fourier para obtener mapas RangeDoppler que permiten junto con el algoritmo CFAR mejorar la detección de objetos al comparar con la detección a partir de un nivel fijo. Se presentan resultados que demuestran que la exactitud y precisión del radar se encuentran dentro de los parámetros para un radar de corto alcance para vehículos, encontrándose, además, una herramienta con gran potencial didáctico, con la cual los estudiantes pueden comprender las aplicaciones que hoy tienen las matemáticas en el ámbito de las telecomunicaciones, especialmente en radares que sirven a sistemas ADAS.//In recent decades, advanced driver-assistance systems (ADAS) have evolved to be available in much of the vehicles manufactured today; it is very im-portant to keep teaching in this area up-to-date. This paper presents a frequency modulated continuous wave radar that works in the 24 GHz ISM band. The purpose of this work is to evaluate its performance and suitability to be used as a didactic tool in teach-ing in the automotive and telecommunications engi-neering careers with an emphasis on the mathematics and telecommunications subjects, under scenarios feasible to be found in university labs. For this pur-pose, the measurement scenario is described, as well as the hardware, firmware and a generic algorithm implemented in MATLAB based on fast Fourier transforms to obtain Range-Doppler maps that allow, in conjunction with the CFAR algorithm, to improve detection of objects when compared to the detection from a fixed level. The results presented demonstrate that the accuracy and precision of the radar are within the parameters for a short-range radar for vehicles, also finding a tool with great didactic potential with which students can understand today´s applications of mathematics in the field of telecommunications, especially in radars that serve ADAS systems.

Precise detection and monitoring of the frequency spectrum of microwave signals are essential to myriad scientific and technological disciplines, including both civil and defense areas, such as telecommunications, radar, biomedical instrumentation, radio astronomy, etc. Historically, microwave engineering has provided solutions for these tasks. However, current radio-frequency (RF) technologies suffer from inherent shortcomings that limit their capability to provide agile (e.g., real-time) measurements over a large operation bandwidth in energy-efficient and compact (e.g., integrated) formats. Overcoming these limitations is key to fulfilling pressing performance requirements in the above-mentioned application fields, as well as for compatibility with platforms that require chip-scale integration and/or low weight and dimensions, such as satellites and drones. Integrated microwave photonics is an emerging field that leverages the advantages of optical technologies for realization of microwave operations with high bandwidth, low power consumption, and increased agility and flexibility in on-chip platforms, offering an alternative path for integration of advanced RF processing and analysis methods in mature semiconductor technologies. This mini review surveys some of the latest advances in microwave spectral measurement and monitoring techniques realized through photonic approaches, with a special focus on methods suitable for on-chip integration.

In multi user scenarios to prevent interference between users that share the same bandwidth at the same time, each user has to transmit waveforms that are uncorrelated with those of other users. However, due to spectrum limitations, the uncorrelated property cannot always be satisfied meaning that interference is unavoidable. In order to alleviate the interference, a framework for interference mitigation is presented. The performance of the proposed framework is tested on simulated and real signals. The real signal is acquired in a controlled laboratory environment using a Software Defined Radio (SDR). The simulated and experimental results show that the proposed framework is capable of mitigating the interference from other users.

Photonics-enabled coherent MIMO radars have been numerically investigated to evaluate the benefits of coherence and multi-band operation in 2/3D imaging.

The evolution of microwave and mm-wave systems for communication and remote sensing is heading towards a massive deployment of phased-array antennas with beamforming capabilities. 5G wireless access networks are expected to employ beamforming to optimize resources allocation, whereas radars will benefit from precise and fast-scanning antennas. Moreover, in the next future, those systems are expected to widely employ photonic technologies for signal generation, acquisition, and distribution. In this scenario, photonics can allow for the development of high-performance beamforming networks, which can easily be integrated in photonics-assisted RF systems, combining broad operational bandwidth, low signal distortion, and high pointing precision with unprecedented flexibility. In this paper, a phase shift-based beamforming network for microwave applications is presented and its performance analyzed. The Si-photonics integrated phase shifters exhibit large phase shift (>360°) and limited amplitude fluctuations (∼2.5 dB). The packaged beamforming network elements show extremely low signal distortion, low steering error (

Today, the advent of radar sensing in applications requiring ever higher precision, such as automotive and industrial monitoring, needs the development of systems with superior resolution, stability and accuracy on 2D/3D spaces. Multiple-input–multiple-output (MIMO) radar systems have been studied for more than twenty years, proving to achieve excellent resolutions by merging simultaneous observations from sparse multiple radars. In addition, long-term frequency/phase coherence among distributed signals to and from remote and widely distributed radar frontends, enables a centralized architecture where, in a common base station (BS) site, all the received signals can be coherently processed in synergy, allowing to further improve detection, localization, and imaging capabilities. Radio-over-fiber (RoF) solutions represent an enabling technology for guaranteeing coherence among all radar signals coherently generated in the BS and distributed/collected to/from the radar heads by means of optical fiber links. Despite the unprecedented frequency-agility provided by photonics-based radiofrequency (RF) up-/down-conversion in the optical domain, for applications requiring massive low-cost production and power efficiency, such as advanced driver-assistance systems, it might be convenient to transmit and receive conventionally generated RF signals, and to limit the use of photonics, as in RoF, to RF signal distribution through cheap high-capacity optical links, in order to avoid EM interference, minimize loss, signal distortion and link encumbrance, still keeping the coherence among distributed signals. In this work, we present a MIMO radar-over-fiber (RaoF) network, where a common BS transmits and receives RF signals through optical standard single-mode fiber (SSMF), to and from two remote radar transmitters (TXs) and four receivers (RXs), all remote with respect to the BS and distributed on a 3 m-long baseline, and employing cheap patch antennas. Electro-optic conversion is achieved through direct modulation (DM) of low-cost, power-effective, and high-speed vertical-cavity surface-emitting lasers (VCSELs) working in the 1.3 µm-wavelength regime. Such a wavelength ensures propagation over SSMF with negligible distortions up to the km-range. The system is tested in a down-scaled indoor scenario and an RF carrier of 8.5 GHz is used, due to the limited frequency response of the employed VCSELs. System performance is evaluated with 1.4 GHz-bandwidth signals, comparing non-coherent and coherent signal elaboration. In addition, dual-band operation in the same RF region is tested, confirming that VCSEL-based optical links are a viable way to guarantee phase coherence among the distributed signals and among multiple frequency bands. Coherent MIMO processing also confirm the potential to achieve superior range and cross-range resolution than non-coherent data fusion.

The modulated wideband converter (MWC) is well-known for a sub-Nyquist wideband sampling capability based on compressed sensing (CS) theory. In this paper, our goal is to use the MWC as a base to design a sub-Nyquist radar electronic surveillance (ES) system. Our focus is then to extend the capabilities of the previous MWC system in order to meet the challenges, i.e., a very long acquisition time, a much larger simultaneous monitoring bandwidth, and a faster digital signal processing receiver. To this end, we present a new performance analysis framework and then a new digital domain receiver. The proposed performance analysis framework will be useful in comparing signal-acquisition performance of the proposed ES system with those of other sub-Nyquist receivers, including those of the classical Nyquist rate receivers, without resorting to extensive simulations. This framework can also be used to study the complex interplays of important system parameters of MWC, such as the sampling rate, the number of parallel channels, the period of Pseudo random sequence, and thus guides us in selecting the right system dimensions and parameters for desired performance. Radar surveillance application has its inherent needs for very long acquisition time and simultaneous monitoring of very large frequency range. To meet this challenge, a fast signal recovery system needs to be developed, so that radar signal logistics can be retained and recovered from compressed samples. We have proposed a split and synthesis process in which the radar signal recovery problem over a long signal acquisition time can be divided into many small CS signal recovery problems, and the solutions for small pieces are put together later on at the end. In addition, a sub-sampling method is proposed to have the multiple measurement vector problem complete signal recovery faster without noticeable performance loss.

Wireless local positioning systems are based on measurements of signal time of flights and/or bearing angles to determine the position of an active transmitter in 3-D space. Traditional time-of-flight and angle measurements with such positioning systems require many data samples at high rates to fulfill the Nyquist criterion. Moreover, in multipath channels the ability of classical signal processing methods to resolve the delay and bearing vectors of the multiple transmission paths is strictly limited by the radio frequency bandwidth and aperture size. In this paper, we show that the wireless channel is ideally suited for the application of compressed sensing. We can thus reduce the number of samples without major losses in localization performance, or we can improve the resolution. After introducing a general model of a localization task with multipath propagation, and following the definition of key parameters of existing systems, we review the necessary data processing stages with compressed sensing and verify its excellent applicability. Finally, measurements are presented to verify the theoretical predictions experimentally.

The millimeter-wave (mmWave) antenna array plays an important role in the excellent performance of wireless sensors networks (WSN) or unmanned aerial vehicle (UAV) clusters. However, the array elements are easily damaged in its harsh working environment but hard to be repaired or exchanged timely, resulting in a serious decline in the beamforming performance. Thus, accurate self-diagnosis of the failed elements is of great importance. In previous studies, there are still significant difficulties for large-scale arrays under extremely low SNR. In this paper, a diagnosis algorithm with low complexity and high reliability for the failed elements is proposed, which is based on a joint decision of communication signal and sensing echoes. Compared with the previous studies, the complexity of the algorithm is reduced by the construction of low-dimensional feature vectors for classification, the decoupling of the degree of arrival (DOA) estimation and the failed pattern diagnosis, with the help of the sub-array division. Simulation results show that, under an ultra-low SNR of &minus, 12.5 dB for communication signals and &minus, 16 dB for sensing echoes, an accurate self-diagnosis with a block error rate lower than 8% can be realized. The study in this paper will effectively promote the long-term and reliable operation of the mmWave antenna array in WSN, UAV clusters and other similar fields.

Millimetre-wave frequency-modulated continuous wave (FMCW) radar is expected to be widely deployed for advanced driver assistance systems (ADAS) and self-driving cars. Considering that automotive radars will be deployed in a huge number of cars in future, inter-radar interference will be a significant problem since inter-radar interference can cause miss-detection and/or false detection of the target. As millimetre-wave automotive radar is not standardised at this moment, it is required to evaluate inter-radar interference among FMCW radars with various chirp-rates and chirp durations. This study describes inter-radar interference analysis in FMCW radars with different chirp rates and simulation results of inter-radar interference to confirm the validity of the interference analysis.

Modern radar applications, such as automotive, integration of radar and communications, have become an important requirement. Systems able to provide joint radar and communications would exploit the same hardware while providing enhanced capabilities to the carrying platform, such as road situation awareness and content sharing. In this article, a novel framework for automotive radars based on the fractional Fourier transform (FrFT) is introduced. The aim of the proposed approach is to preserve radar performance while integrating a communication link. Simulation results demonstrate the potential of the proposed framework for automotive applications.

In automotive environment, it is preferable to have a joint radar and communication system as it is able to use the same hardware and band of the spectrum for both systems. In this paper a joint radar communication system for automotive radar based on the Fractional Fourier Transform (FrFT) is presented. The performance of the system is analysed in the presence of interference arising from other users. In addition, the communication performance in terms of Bit Error Rate (BER), is analysed for different scenarios. Simulation results demonstrate the potential of the proposed system in multi-user scenarios and in different types of communication channels.

In automotive systems, a radar is a key component of autonomous driving. Using transmit and reflected radar signal by a target, we can capture the target range and velocity. However, when interference signals exist, noise floor increases and it severely affects the detectability of target objects. For these reasons, previous studies have been proposed to cancel interference or reconstruct original signals. However, the conventional signal processing methods for canceling the interference or reconstructing the transmit signals are difficult tasks, and also have many restrictions. In this work, we propose a novel approach to mitigate interference using deep learning. The proposed method provides high performance in various interference conditions and has low processing time. Moreover, we show that our proposed method achieves better performance compared to existing signal processing methods., Accepted in 2018 VTC workshop

This paper reviews linear cell radar systems, which are radar systems consisting of many antenna units connected by radio-over-fiber to monitor linear-shaped areas. A linear cell system using a millimeter-wave band can provide high-resolution imaging for foreign object detection on runways. Electro-optic devices play important roles in linear cell systems to provide a conversion between optical and electric signals. This paper describes overviews of such devices including light sources, photodetectors, and optical modulators, etc.

The last two decades were marked by increasing of interest in problems of application of the MIMO systems in a radar and wireless communication. Use of the principles of creation of MIMO systems in communication complexes allows increasing the capacity of channels and speed of information transfer due to increase in number of the transferring and reception antennas. In the report questions of modernization of antennas of the wearable mobile communication devices allowing to reduce correlation of channels and to increase spectral system effectiveness of communication are considered. Results of a research of mutual correlation reduction between two antennas of MIMO system are given. Using method of numerical modelling influence of several options of the decoupling structures on interconnection size between radiators and on their directional patterns were investigated. Comparative results of a pilot study of the model of antennas with the outcome device having the best characteristics and without the decoupling device are presented.

This paper investigates the target detection and localization capabilities of a coherent multiple input multiple output (MIMO) radar network designed and implemented using photonic technology. The benefit offered by photonics is twofold: it guarantees long-time phase stability and frequency/phase coherence between the transmitted and received radio frequency signals; secondly, it allows remoting the antennas by exploiting optical fibers. The proposed radar network demonstrator, which is composed of two transmitting and two receiving antennas in the X-band with 100 MHz signal bandwidth, operates in a real down-scaled outdoor scenario for detecting two collaborative closely-spaced moving targets. The preliminary results demonstrate the effective impact of photonics applied to coherent centralized radar networks and provide some guidelines for the development of more complex and application-tailored radar networks.

In the automotive sector, both radars and wireless communication are susceptible to interference. However, combining the radar and communication systems, i.e., radio frequency (RF) communications and sensing convergence, has the potential to mitigate interference in both systems. This article analyses the mutual interference of spectrally coexistent frequency modulated continuous wave (FMCW) radar and communication systems in terms of occurrence probability and impact, and introduces RadChat, a distributed networking protocol for mitigation of interference among FMCW based automotive radars, including self-interference, using radar communications. The results show that RadChat can significantly reduce radar mutual interference in single-hop vehicular networks in less than 80 ms., 14 pages, 17 figures, 1 table, published in IEEE Transactions on Intelligent Transportation Systems

The performance of the wavelength division multiplexing (WDM) photonic analogue-to-digital converter (ADC) used for digitization of high-resolution radar systems is evaluated numerically by using the peak signal-to-noise ratio (SNR) metric. Two different WDM photonic ADC architectures are considered for the digitization of radar signals with 5 GHz of bandwidth (spatial resolution of 3 cm), in order to provide a comprehensive study of the compromises present when deploying radar signals with high-resolution: 1) a four-channel architecture with each channel employing an ADC with 5 GSamples/s, and 2) an eight-channel architecture with each channel employing an ADC with 2.5 GSamples/s. For peak powers of the pulsed source between 10 and 20 dBm and a distance between the radar antenna and the sensing object of 2.4 meters, peak SNR levels between 29 and 39 dB are achieved with the eight-channel architecture, which shows higher peak SNR levels when compared with the four-channel architecture. For the eight-channel architecture and for the same peak powers of the pulsed source, peak SNR levels between 11 and 16 dB are obtained when the distance increases to 13.5 meters. With this evaluation using the peak SNR, it is possible to assess the performance limits when choosing a specific radar range, while keeping the same resolution. info:eu-repo/semantics/publishedVersion

In this paper, we propose a new architecture and provide performance analysis for frequency diverse array (FDA) Radar combined with the index modulation (IM) techniques. Here, the IM concept is applied upon frequency offsets in an FDA. Information is transmitted by a dynamically selected subset of antenna element indices applying predefined carrier frequency offsets, which generate different radiation patterns. It is shown that this enables the capability for simultaneous wireless communication and FDA Radar that has the range-angle coupling issue resolved.

This paper presents a novel resonator that can switch and create three important behaviors within the same antenna using miniaturized capacitors. The resonator was integrated into conventional Ultra-Wide Band (UWB) antenna to achieve UWB and Single/Dual continuously tunable-notch behaviors. The Single/Dual notched was continuously tuned to our desired frequency band by changing the value of the capacitors. The antenna designed and fabricated to validate these behaviors had a compact size of 24 ? 30.5 mm2, including the ground plane. The radiation patterns were very clean due to the placement of the proposed resonator in the special ground plane. Moreover, the presented novel resonator and switching technique was compared with the recently proposed resonators and their switching techniques. The prototype for the antenna was also developed in order to validate its performance in wireless vital signs monitoring. The presented miniaturized resonator based antenna was utilized for tumor sensing and simulations were provided in this regard. Moreover, the deployment of the proposed resonator based UWB antenna sensor in Pipeline Integrity Monitoring system was also investigated and discussed. ? 2018 by the authors. Licensee MDPI, Basel, Switzerland. Scopus

The article describes the results related to development of microwave transistors, which are to be used in electronic components for satellite systems. The advantages of facilitation of nitride and gallium technologies in receiving and transmitting modules of the radar with space purposes AFAR have been investigated

Multiple factors have to be taken into account when mobile telecommunication network providers make decisions about radio transmitter placement. Generally, area coverage and the average signal level provided are of prime importance in these decisions. These criteria give rise to a bi-objective problem of facility location, with the goal of achieving an acceptable trade-off between maximising the total area coverage and maximising the average signal level provided to the demand region by a network of radio transmitters. This paper establishes a mathematical modelling framework, based on these two placement criteria, for evaluating the effectiveness of a given set of radio transmitter locations. In the framework, coverage is measured according to the degree of obstruction of the so-called ‘Fresnel zone’ that is formed between handset and base station, while signal strength is modelled taking radio wave propagation loss into account. This framework is used to formulate a novel bi-objective facility location model that may form the basis for decision support aimed at identifying high-quality transmitter location trade-off solutions for mobile telecommunication network providers. But it may also find application in various other contexts (such as radar, watchtower, or surveillance camera placement optimisation).

Multiple-input–multiple-output (MIMO) radar has received much attention in recent years for its great ability in imaging. However, the essence of MIMO radar has not been fully implemented due to the lack of proper transmission waveforms. In MIMO radar, the transmission waveform of each channel has to be uncorrelated with one another to avoid cross-interference between channels. To achieve this, we investigate the generation of uncorrelated multichannel chaos using electrical heterodyning for MIMO chaos radar (MIMO CRADAR) application. By electrically heterodyning a seed chaos source with multiple single-frequency local oscillators, chaos with different heterodyned spectra can be extracted and converted into multiple chaos channels. In this paper, the correlations between different channels of chaos generated are analyzed both numerically and experimentally. The minimal frequency spacing of the local oscillators for generating the largest amount of uncorrelated chaos channels is discussed. In our analysis, thousands of uncorrelated chaos channels can be simultaneously generated with a correlation time of several microseconds. Moreover, compared with those conventional waveform-designing methods that require complicated optimization and digital-to-analog conversion (DAC), the proposed heterodyned technique shows, for the first time, that multiple uncorrelated channels can be generated in real-time while breaking the bandwidth limitation of the DAC devices. A proof-of-concept experiment is successfully demonstrated to show the feasibility of using multichannel heterodyned chaos in the MIMO CRADAR application.

International audience; In this paper, we deal with a frequency modulated continuous wave (FMCW) radar used for localizing and tracking targets by frequency evaluation of the received radar beat signal. The radar system achieved with a primary radar (reader) and a secondary radar (transponder) is addressed as super high frequency (SHF) radio frequency identification (RFID). Consequently, considering the transponder as an active target, we achieve an identification application thanks to the shift frequency induced by the transponder. Moreover, the impact of the non-linearity behavior of this transponder on the localization performance, is investigated and a solution is proposed for cancelling non-linear effects.

The integrated radar and communication system is promising in the next generation wireless communication networks. However, its performance is confined by the limited energy. In order to overcome it, a wireless powered integrated radar and communication system is proposed. An energy minimization problem is formulated subject to constraints on the radar and communication performances. The energy beamforming and radar-communication waveform are jointly optimized to minimize the consumption energy. The challenging non-convex problem is solved by using semidefinite relaxation and auxiliary variable methods. It is proved that the optimal solution can be obtained. Simulation results demonstrate that our proposed optimal design outperforms the benchmark scheme., This paper was accepted by IEEE Wireless Communications Letters

International audience; The multi-antenna receiver has many usecases in wireless communications and Radar but it facessome major drawbacks such as high cost of hardware andhigh power consumption. Recent developments on narrowband systems have led to an alternative solution calledCode-Division Multiplexing (CDM), using a single RFreceiver front-end to receive signals from multi-antenna.For this purpose signals from the antennas are mixedwith high speed spreading codes and then are combinedat the RF stage. However, the use of high speed codesincreases the signal bandwidth. Applying this solution onUltra-Wide Band (UWB) systems is questionable because ofthe bandwidth increase. This paper discusses the principlesand implementation of CDM technique on an ImpulseRadio (IR) UWB system showing interesting insights. Anexperiment is performed to estimate the Angle-Of-Arrival(AOA) on the recovered signals in a basic indoor positioningscenario.

This study presents experimental analysis of range error of modular FMCW (frequency modulated continuous wave) radar operating at C-band. As FMCW utilizes frequency modulation, it can measure both range and speed of targets. One of the problems arising in the design of modular FMCW radar is error due to time delays in components and/or modules (Modular Component Delay-MCD). Then, MCD is taken into account to improve the accuracy of range measurement, and range error is quantized. This form of time delay causes frequency offset in measured beat frequency resulting in range error. Therefore, the resulting frequency offset of the radar is estimated and quantized experimentally. In this way, a mean error of about 11cm was achieved within 9m range measurements for C Band modular FMCW radar.

Millimetre wave radar is an essential part of automotive safety functions. A high interference tolerance, especially with other radar sensors, is vital. This paper gives an overview of the motivation, the boundary conditions and related activities in the MOSARIM project funded by the European Union and concerned with interference mitigation in automotive radars. Current and planned activities considering Digital Beamforming (DBF) as a method for interference mitigation are presented.

In this paper we propose one possible approach how to apply the concept of multiple-input multiple-output (MIMO) to monostatic Frequency Modulated Continuous Wave (FMCW) High-Frequency Surface Wave Radar (HFSWR) in a maritime environment. Common tasks for a HFSWR are sea-state monitoring and ship detection, where our focus is on ship detection. A limiting factor in HFSWR is the available bandwidth, which is inversely proportional to the range resolution capability of the radar and typical below 100 kHz. The question is how to extend or combine a conventional single-input multiple-output (SIMO) FMCW phased-array type radar with stretch processing and the colocated MIMO concept to "reuse" the very limited HF radar band resources. Another important question to answer is how MIMO FMCW waveforms can be separated at the receiver.

International audience; In the single-input multiple-output radar, the system transmits scaled (coherent) versions of a single waveform. The multiple-input multiple-output (MIMO) radar uses multiple antennas to simultaneously transmit several non-coherent waveforms and exploits multiple antennas to receive the reflected signals (echoes). This diversity in term of waveform coding allows to transmit orthogonal waveforms which enables the MIMO radar superiority in several fundamental aspects, including: improved parameter identifiability and estimation and much enhanced flexibility for transmit beam-pattern design. The context of this work is the co-located MIMO radar where the transmit and the receive arrays are close in space. In this paper, we provide a theoretical performance analysis to compare two configurations of MIMO radar: Conventional configuration and Time Reversal (TR) configuration in term of Statistical Resolution Limit (SRL). This study provides new insights on the performance gain of the TR scheme which is discussed and illustrated by appropriate simulation results depending on the receive noise level.

Increasing resolution is an attractive goal for all types of radar sensor applications. Obtaining high radar resolution is strongly related to the signal bandwidth which can be used. The currently available frequency bands however, restrict the available bandwidth and consequently the achievable range resolution. As nowadays more sensors become available e.g. on automotive platforms, methods of combining sensor information stemming from sensors operating in different and not necessarily overlapping frequency bands are of concern. It will be shown that it is possible to derive benefit from perceiving the same radar scenery with two or more sensors in distinct frequency bands. Beyond ordinary sensor fusion methods, radar information can be combined more effectively if one compensates for the lack of mutual coherence, thus taking advantage of phase information. At high frequencies, complex scatterers can be approximately modeled as a group of single scattering centers with constant delay and slowly varying amplitude, i.e. a set of complex exponentials buried in noise. The eigenanalysis algorithms are well known for their capability to better resolve complex exponentials as compared to the classical spectral analysis methods. These methods exploit the statistical properties of those signals to estimate their frequencies. Here, two main approaches to extend the statistical analysis for the case of data collected at two different subbands are presented. One method relies on the use of the band gap information (and therefore, coherent data collection is needed) and achieves an increased resolution capability compared with the single-band case. On the other hand, the second approach does not use the band gap information and represents a robust way to process radar data collected with incoherent sensors. Combining the information obtained with these two approaches a robust estimator of the target locations with increased resolution can be built.