Vehicular Radar Systems Research Articles

Decoupling Methods in Planar Ultra-Wideband Multiple-Input-Multiple-Output Antennas: A Review of the Design, State-of-the-Art, and Research Challenges

Ultra-wideband (UWB) antennas cover a frequency range of 3.1 to 10.6 GHz and have sparked a lot of research interest as an essential part of wireless communication systems as they provide high data transmission speeds, are less expensive, and consume less power. UWB antennas are widely used in radar imaging, radio frequency identification, public security, and other high-accuracy positioning devices such as altimetry. Some smart applications of UWB antennas are vehicular radar systems, surveillance systems, software-defined radios, spectrum analysis, proximity fuses, etc. Multiple-input-multiple-output (MIMO) is a multiplexing technology that adopts multiple antennas both at the transmitter and receiver, which can enhance the channel capacity. MIMO technology is extensively used in several applications, such as in portable devices, wireless body area networks (WBANs), vehicular communication, and satellite–terrestrial networks. Generally, the MIMO antennas are used to obtain high reliability, high capacity, high throughput, and high security. The UWB MIMO antennas (UMAs) are considered the best choice for wireless communication systems as they offer reliability and wide transmission capacity, in contrast to unit antenna elements (AEs), without increasing system bandwidth or transmission power. The present-day and future communications systems need higher throughput to meet the demands of users. The signal transfer rate can be improved by improving channel bandwidth or increasing the number of receiving antennas. However, the main issue in designing UMAs is to provide high isolation between AEs because mutual coupling interactions between them affect the generated radiation patterns, leading to worse performance and failing to meet the operative constraints and requirements. When introducing decoupling techniques (DTs), researchers experience numerous challenges, including an increase in antenna size, design complexity, and cross-polarization. This article offers an organized review and simulated study of the various DTs in UMAs. The simulated study has been carried out through the implementation of various types of DTs on the same two-port UMA, which consists of two microstrip-fed circular-shaped AEs with open-end slotted partial ground. In contrast with previously reported review articles, this article provides a detailed study of various types of DTs reported so far and a better understanding for selecting appropriate DTs, which help in designing UMAs with better performance.

Echo Signal Enhancement for ESPRIT to Estimate Angles of Arrival by Virtually Overlapped Subarray Decomposition in ADAS Radar Systems

Angle of arrival (AoA) for target echo signal detection is crucial in vehicular radar systems, where the estimation of signal parameters via rotational invariance (ESPRIT) provides a high-resolution estimation. A subarray decomposition strategy is presented in this article to create two ESPRIT antenna arrays with enhanced echo signal strengths, applicable to multi-input–multioutput (MIMO) operations for creating a large virtual array. The concept intends to maximize the echo signal’s strength with minimum signal interferences by increasing the aperture sizes of the two ESPRIT antenna arrays. The decomposition produces two virtually overlapped subarrays to increase the subarray aperture sizes in the spatial or spectral representations. It is applied to the MIMO-based arrays for two-way radiation patterns for ESPRIT estimation of AoA. Numerical simulation examples are shown to validate the feasibility and demonstrate the applications.

Radar Imaging Based on IEEE 802.11ad Waveform in V2I Communications

Since most of vehicular radar systems are already exploiting millimeter-wave (mmWave) spectra, it would become much more feasible to implement a joint radar and communication system by extending communication frequencies into the mmWave band. In this paper, an IEEE 802.11ad waveform-based radar imaging technique is proposed for vehicular settings. A roadside unit (RSU) transmits the IEEE 802.11ad waveform to a vehicle for communications while the RSU also listens to the echoes of transmitted waveform to perform inverse synthetic aperture radar (ISAR) imaging. To obtain high-resolution images of the vehicle, the RSU needs to accurately estimate round-trip delays, Doppler shifts, and velocity of vehicle. The proposed ISAR imaging first estimates the round-trip delays using a good correlation property of Golay complementary sequences in the IEEE 802.11ad preamble. The Doppler shifts are then obtained using least square estimation from the echo signals and refined to compensate phase wrapping caused by phase rotation. The velocity of vehicle is determined using an equation of motion and the estimated Doppler shifts. Simulation results verify that the proposed technique is able to form high-resolution ISAR images from point scatterer models of realistic vehicular settings with different viewpoints. The proposed ISAR imaging technique can be used for various vehicular applications, e.g., traffic condition analyses or advanced collision warning systems.

Coordinated Cognitive Risk Control for Bridging Vehicular Radar and Communication Systems

As an essential part of the emerging Internet of Things, connected and autonomous vehicles (CAVs) have the potential to reshape future transportation systems and change the commute style in people’s everyday life. Among many vehicular on-board devices, radar system and vehicle-to-vehicle (V2V) communication system are two important pillars for the realization of CAVs. In this paper, the concept of coordinated CRC (C-CRC) is proposed to serve as a cognitive mediator for bridging vehicular radar and communication systems. By establishing a mutual-assistance relationship, C-CRC provides a new safety mechanism that allows one system to learn from and react to the risks that the other system has encountered. Simulation results have shown that the proposed method has desirable performance in face of motion perturbation and/or jamming attack under various scenarios.

Beam splitting of a novel triple-beam slot antenna array based on radial gap waveguide

We present a phenomenon of beam splitting caused by asymmetric boundaries. We design and manufacture a novel triple-beam slot antenna array working at the X-band to verify this phenomenon and show its potential applications. The corporate-feed slot antenna is based on a radial ridge gap waveguide (RGW) power divider, and is excited by a central coaxial connector. To achieve good efficiency, a radial SMA–RGW transition structure is proposed. Six different symmetrical and asymmetrical triple-beam RGW slot antenna arrays are mentioned in this paper. Among them, two symmetrical and one asymmetrical triple-beam RGW slot antenna arrays are fabricated and measured, and the measured results have good agreement with full-wave simulations, demonstrating stable performance of the proposed antenna array. Compared with the traditional slot antenna array, the proposal is capable of generating any number of beams in theory, especially odd beams, and each beam can be individually designed. The proposed shared-aperture radial multi-beam antenna can achieve simultaneous multi-directional coverage. It can meet the needs of multi-target tracking and imaging in blind spot detection and collision warning scenarios of the vehicular radar system. It also has potential value for satisfyimg the need for large-scale users to be connected in the wide-area continuous coverage scenario of the fifth generation communication system.

Embedded Rectangular Dielectric Resonator Antenna for KuBand Applications

In this paper an Embedded Dielectric Resonator Antenna (EDRA) excited by a micro-strip line is designed and investigated. This novel design consists of a 50×50 mm2 substrate with permittivity e_s equals to 4.5 (Roger TMM 4 ™). Main radiating structure is made up of Roger RT Duroid 6010/6010 LM (tm), permittivity e_r= 10.2 and loss tangent of 0.0025 having dimension0.21λ×0.73λ×0.57λ at 12.4 GHz. The proposed antenna has radiation efficiency of 90.51% with peak gain of 6 dB at 11 GHz. This antenna shows maximum return loss of 33.03 dB at 12.48 GHz with stable impedance bandwidth of 12.98%. This proposed antenna is suitable for vehicular radar system, imaging and modern wireless communication system.

Cognitive Risk Control for Transmit-Waveform Selection in Vehicular Radar Systems

Cognitive dynamic system (CDS) is a structured engineering model and research tool inspired by certain features of the human brain. As a special function of CDS, cognitive risk control (CRC) actualizes the concept of predictive adaptation to bring risk under control when encountered with unexpected uncertainty. In this paper, the first experimental demonstration of CRC is presented in the practical application of vehicular radar systems, and an algorithm for transmit-waveform selection in cognitive vehicular radar (CVR) based on CRC is proposed. During each perception–action cycle, the perceptor of CVR processes new environmental inputs and provides the processed information to the executive through feedback channel for the selection of cognitive action. With the mechanism of task-switch control being functional all the time, the CVR will switch to a more capable operation mode in the face of unexpected disturbances or adverse events. In such cases, a new subsystem of executive is brought into play, in which the risk-sensitive cognitive action is finally selected and applied to the environment. Simulation results have shown the robustness and effectiveness of the proposed CVR system, which can make the next-generation vehicular radars more intelligent and play an important role in future self-driving cars.

Compact circular-patch-based bandpass filter for ultra-wideband wireless communication systems

Ultra-wideband (UWB) is a radio technology that enables low-power-level, short-range, and wide-bandwidth communication, and it has been widely applied in personal area networks, precision geolocation, medical, surveillance, and vehicular radar systems. Since Federal Communications Commission released the unlicensed use of the UWB range (3.1–10.6GHz), a significant attention has been paid to the development of UWB devices, particularly UWB bandpass filters. In this paper, we propose a novel UWB bandpass filter based on circular patch resonator that is grounded by via and perturbed by slits and defected ground structures. The resonator’s behaviour is analysed in detail and it is shown that its specific configuration allows a flexible control of the three lowest resonant modes, which are used to form UWB passband. To demonstrate the potential of the resonator, a UWB filter has been designed, fabricated, and measured. The filter is characterized by the insertion loss lower than 1dB and return loss higher than 17dB within the passband, as well as by very small group delay variation of only 0.07ns. Also, the filter exhibits suppression higher than 19dB up to 30GHz, and very small overall dimensions of only 0.31λg×0.31λg, and thus it outperforms other published UWB filters.

ZCZ 부호를 이용한 상호간섭에 강인한 차량용 확산대역 레이더 방식

We propose vehicular spread spectrum (SS) radar robust to mutual interference using zero correlation zone (ZCZ) code. SS radar schemes have been employed for vehicular radar systems due to their outstanding correlation property. However, this superiority is based on a premise that timing among codes is completely synchronized. In the practical driving environment, timing mismatch among radar signals is inevitable because the radar signals of several vehicles are independently transmitted at each different location and each timing and thus each radar signal is received at different timing. This timing offset is the main cause of orthogonality destruction among codes and thus radar signals from other vehicles become mutual interference. In order to solve this problem, we find out the new property of ZCZ code which maintains the complete orthogonality except to timing offset corresponding to chips (pulses) of multiple of 4 and employ ZCZ code to SS radar systems. Simulation results show the proposed scheme achieve better performance compared with the conventional SS radar scheme using pseudo code or gold code.

Millimeter wave band ultra wideband transmitter MMIC

This paper presents a new millimeter-wave (MMW) ultra wideband (UWB) transmitter MMIC which has been developed in an OMMIC 0.1 μm GaAs PHEMT foundry process (ft = 100 GHz) for 22–29 GHz vehicular radar systems. The transmitter is composed of an MMW negative resistance oscillator (NRO), a power amplifier (PA), and two UWB pulse generators (PGs). In order to convert the UWB pulse signal to MMW frequency and reduce the total power consumption, the MMW NRO is driven by one of the UWB pulse generators and the power amplifier is triggered by another UWB pulse generator. The main advantages of this transmitter are: new design, simple architecture, high-precision distance measurements, infinite ON/OFF switch ratio, and low power consumption. The total power consumption of the transmitter MMIC is 218 mW with a peak output power of 5.5 dBm at 27 GHz.

Carrier-Based Cmos Impulse Generator for Ultrawideband Vehicular Radar Application

This article presents a CMOS ultrawideband (UWB) impulse generator using a 0.13-μm CMOS technology for the application of UWB 22–29-GHz vehicular radar. The proposed impulse generator has a pulse-modulated carrier-based architecture. The proposed design is power efficient and spectrum controllable with a frequency tuning range of 800 MHz. The output impulse has a pulse width less than 0.55 ns providing a high range resolution for the UWB vehicular radar systems. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1881–1887, 2013 10.1002/mop.27715

Robust adaptive controller with disturbance observer for vehicular radar servo system

In vehicular radar servo system, parameter variations of the executive motor and external disturbance uncertainties have great effects on the position tracking precision of the system. In this paper, a robust adaptive controller with disturbance observer is designed for vehicular radar servo system, which combines the merits of disturbance observer, adaptive backstepping method and sliding mode control. The system is modeled, and a disturbance observer is employed to observe and compensate for the unknown uncertainties. Adaptive backstepping method is used to design the sliding model controller to guarantee the global stability of the overall system. Simulation results show that the proposed robust adaptive controller has good performance in position tracking and enhances the robustness of vehicular radar servo system while observing the uncertainties precisely and quickly.

ICUWB 2009 to Focus on Microvave and Millimeter Wave Band Technology, IEEE International Conference on Ultra-Wideband will Meet on 9–11 September 2009 in Vancouver

IEEE International Conference on Ultra-Wideband Will Meet on 9 - 11 September 2009 in Vancouver In Vancouver on 9-11 September, the 2009 IEEE International Conference on Ultra-Wideband will center around the topic of UWB transmission in micro-wave and millimeter wave bands and over power lines. It will focus on the latest advances in UWB technology, current and future applications ranging from UWB communication for personal area and sensor networks to UWB-based localization and positioning systems to UWB vehicular radar and imaging systems, and standardization and regulation for UWB transmission

A compact and low‐loss sub‐millimeter‐wave ultra‐wideband bandpass filter

AbstractThis paper presents a new compact, low‐loss sub‐millimeter‐wave ultra‐wideband (UWB) bandpass filter (BPF) designed for vehicular radar systems. A dual‐mode ring resonator loaded with two 3λ0/4 open stubs is used in the filter to realize a passband width of about 30%. In order to widen the stopbands of the filter significantly, a multiple‐mode parallel‐coupled line structure is introduced at the output of the ring resonator. Due to the transmission zeros in the lower and upper stopbands of the filter produced by the dual‐mode ring resonator and the multiple‐mode parallel‐coupled line structure, the filter exhibits good performance including sharp attenuations near the passband, and an extremely wide stopband, together with low insertion and return losses in the passband. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 481–484, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22149

Ultra-Wideband and Its Capabilities

Ultra-wideband (UWB) can be seen as a disruptive technology for business and home wireless networking. Research into UWB systems can be dated back to the early 1960s, but until recently the main focus has been on radar-based, military secure radio and intrusion detection systems, as the short pulses of the signal results in very accurate timing information. However, recent improvements in device capability, and the demand for fast and high-capacity wireless connections means that UWB is becoming increasingly attractive in the consumer market. Specifically, advances in application-specific integrated circuits and complementary metal oxide semiconductors have reduced chip costs, and improvements in micro-electrical mechanical systems make UWB easier to manufacture in RF chips. Further, recent regulatory rulings in the USA by the Federal Communications Commission permit applications of UWB in the areas of vehicular radar systems, imaging systems and communications and measurement systems. The new regulation provides great opportunities for UWB companies to develop and release their products in a vast array of new applications. Further, the FCC regulation has stimulated a new approach to UWB: multi-band UWB, which may be of direct relevance to multi-user communications systems. However, UWB approval is not straightforward due to several important factors including the impact on existing radio services. And while UWB can offer many advantages, there are many technical challenges in the design of UWB systems. A team in BT Exact has been investigating these issues, along with the technology movement and types of new service that could be carried by UWB systems. The objective of this paper is to provide an understanding of UWB technology by firstly examining fundamentals of how it works, followed by possible applications.