DOCSLIB.ORG

Post Beam Steering Techniques As a Means to Extract Horizontal Winds from Atmospheric Radars

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Post Beam Steering Techniques As a Means to Extract Horizontal Winds from Atmospheric Radars Post beam steering techniques as a means to extract horizontal winds from atmospheric radars VN Sureshbabu1, VK Anandan1, Toshitaka Tsuda2 1ISTRAC, Indian Space Research Organisation, Bangalore -58, India 2Research Institute for Sustainable Humanosphere (RISH), Kyoto University, JAPAN (Dated: 30 May 2012) (V.N.SURESHBABU) Abstract Postset Beam Steering (PBS) technique has been used to extract horizontal winds from the data collected from multi receiver phased array atmospheric radar (Middle and Upper (MU) atmospheric radar). PBS includes various signal processing algorithms such as beamforming, spectral estimation, moments estimation and etc. Capon beamformer is used for beam synthesizing in the desired direction within the radar beam width. Using the synthesized beam, the power spectrum is obtained through various power spectral estimation methods such as Fourier (non-parametric), Multiple Signal Classification (MUSIC) and Eigenvector (EV) methods. A study has been carried out to analyze the performances of the spectral estimators for better moments computation and thus wind estimations. Results suggest that EV based spectral estimation is a best approach (among three) for complete wind profiling up to the maximum height about 20 km with a temporal resolution about 1.3 min. The analyzed results are in good agreement with other wind observational methods in contiguous time. 1. Introduction Over the past few decades, radar remote sensing of winds is of interest in the tropospheric and upper atmospheric profiling communities. Doppler beam swinging (DBS) is one of the simplest observational methods in which radar antenna main beams are directed in the vertical or near vertical direction to measure the wind components i.e. zonal, meridional and zenith. Zonal and meridian components are generally called as horizontal wind velocities along east-west and north-south directions respectively and zenith component as vertical velocity. In DBS based observations, the wind components are obtained by using line of sight angles and radial velocities of the incoming signals. A minimum of three beams are formed by introducing phases electronically at corresponding antenna elements to derive wind vectors by DBS based method. Also, five beams (one as vertical beam and four as oblique beams) are used for 3-D wind estimation in MST and other wind profiling atmospheric radars. PBS technique was initially demonstrated in wind profiling [6] as a means of software steering using multi receiver data. Since these measurements typically involve reception on minimum three spatially separated arrays, a systematic phase shift can be applied to the signals to produce a two-way beam pattern in any arbitrary direction within the volume illuminated by the transmitted beam. In this article, a comparative study has been carried out using spectral based techniques on data received from middle and upper atmospheric (MU) radar [5] at Shigaraki, Japan. MU radar, mono static pulsed phased array radar, operates at 46.5 MHz with a peak power of 1 MW. The antenna array is also capable of steering the beam electronically using phase shifters in transmit and receive path. The experiment was conducted with full array of transmission (beam width 3.6o) in vertical direction. Signals received from spatially separated antennas are made to interfere constructively by phasing the received signals within the transmit beam width. This technique is used to synthesize the beams in the desired directions and so called as Post Beam Steering Technique (PBS) [3]-[4], [6]-[7], [12]-[14]. As these measurements typically involve reception of signals by minimum three spatially separated arrays, the vertically received signals are steered along the desired line of sight angle by introducing systematic phase shifts in the received signals themselves. The beam steering can be optimized by weighting vectors through beamforming approach like Capon method [2], [9]-[12]. Then the weighted steered signals are combined linearly to produce a two-way beam pattern in the desired line of sight angle within the transmit beam volume. The beams are independently synthesized for an off zenith angle (tilt angle) of 1.5o and equally separated 32 different azimuth angles within the transmit beam width (3.6o). The power spectrum in the desired AOA is obtained by various spectral estimation methods, such as Periodogram (Fourier), MUSIC [1], [9]-[10] and EV, from the synthesized beam in a given direction. As the power spectrum is obtained by various power spectral estimation methods, a comparative study has been carried out to analyze the performances of the spectral estimators for better moments computation [15] and thus wind estimations. Results suggest that EV based spectral estimation is a best approach (among three) for complete wind profiling up to the maximum height about 20 km with a temporal resolution about 1.3 min. The obtained results are compared with other wind observational methods like DBS and GPS sonde in contiguous time. This paper is organized as follows. Mathematical background of the work is given in section-2. System description and data processing are given in section-3. Result analysis with discussion and conclusion are given in the section-4 and section-5 respectively. 2. Mathematical background A. Signal Model The development of a signal model is based on several assumptions. First, multiple incident sources are assumed to be narrowband sources and located in the field far from the array elements. Second, incident sources are considered as point sources. Third, the propagation medium is homogeneous, and the signal arriving at the array is considered to be as a plane wave. Consider two dimensional arbitrary phased array radar composed of N receivers. For an N- element antenna array of arbitrary geometry, the signals (as a function of time) received by N elements along zenith direction at time t can be represented in a column matrix as T (1) S(t) = [S1 (t) S 2 (t) S 3 (t) SN (t)] where S(t) is the received signal matrix at time t along zenith direction and the superscript T denotes the transpose of the matrix. In this section, bold letters indicate to vector or matrix representation. Now, the signals (as a function of time) steered along the desired direction (,) , within the transmit beam width, at time t can be modeled as [8]- [10] X(t)=( aθ, ) S(t) (2) T where X(t) = [X1 (t) X 2 (t) X 3 (t) XN (t)] is the steered signal matrix at time t along the desired direction (,) using vertically received signal at time t (given in Eqn.1) and a(,) is the steering vector. For an arbitrary array, the steering vector a(,) takes the form as -j(Φ ) -j(Φ )-j(Φ) -j(Φ ) T a(θ, ) = [e12 e e3N e ] (3) -j(Φ ) -j(Φ ) -j(Φ ) where e12 ,e ,...., e N are complex phase shift required at the array elements 1,2….,N respectively to steer the vertically received signals in the desired direction during the beam synthesizing in post processing. For example, the phase angle Φi in the above Eqn.3 can be given as 2π Φ = (D sinθsin +D sinθcos +D cosθ) iλ ix iy iz th where is wavelength of transmitted signal and Dix , D iy , D iz are the components of position vector of i element along x, y, z axes with respect to origin or center of the array. From Eqn.1, the steered signal X(t) along the desired direction (,) results in a scalar product of steering vector a(,) and vertically received signal S(t). In the presence of an additive noise n(t), we now get the model commonly used in array processing as X(t) a(,) S(t) n(t) (4) where n(t) has the same dimension of S(t). The array covariance matrix R in the forward case can be written as HH R= E X(t)X (t) = a (θ, φ) Rs a (θ, φ)+ Q (5) where Rs and Q are the signal (steered) and noise auto covariance matrices with dimension NN, E denotes ∧ statistical expectation and the superscript H represents conjugate transpose of the matrix. A natural estimate R [8] is the sample auto covariance matrix R, which is given as ∧ 1 m H RXX= (k) (k) (6) m k=1 where m is number of points in the time series signal. The auto covariance matrix given above plays an important factor in both parametric and non-parametric spectral estimation methods. For an arbitrary radar array, this beamformer maximizes the power of the beamforming output in the desired direction (within the transmitting beam width) for a given signal X(t) and hence acts as a spatial filter. The spatially filtered signal is obtained as H Y(t) = w X(t) (7) B. Capon Beamformer Capon’s minimum variance method [12] is a AOA estimation technique. It is a beamformer developed to overcome the poor performance of conventional beamformers when multiple narrow band sources present from different AOAs. In this case, the array output power contains a contribution from the desired signal as well as the undesired ones from other AOA estimations. This property will limit the resolution of the conventional beamformer. Capon proposed to minimize the contribution of undesired AOAs by minimizing the total output power while maintaining the gain along the look direction as constant. The weight vector w is given by -1 Ra(,) w s (8) H -1 a(,)(,) Rs a The weight obtained by the above equation is also called the Minimum Variance Distortionless Response (MVDR). Substituting (8) in (7), one can get optimized time series signal in the desired direction within the transmitting beam width. The Capon’s method gives better performance than the conventional beamformer. However, Capon’s method still depends on the number of element array and on the SNR. C. Spectral estimation Frequency estimation is the process of estimating the complex frequency components of a signal in the presence of noise.
Load more

Recommended publications
  • Agile 3-D Beam-Steering for 60 Ghz Wireless Networks Anfu Zhou∗, Leilei Wu∗, Shaoqing Xu∗, Huadong Ma∗, Teng Wei†, Xinyu Zhang‡ ∗ Beijing Key Lab of Intell
    Following the Shadow: Agile 3-D Beam-Steering for 60 GHz Wireless Networks Anfu Zhou∗, Leilei Wu∗, Shaoqing Xu∗, Huadong Ma∗, Teng Weiy, Xinyu Zhangz ∗ Beijing Key Lab of Intell. Telecomm. Software and Multimedia, Beijing University of Posts and Telecomm. y Department of Electrical and Computer Engineering, University of Wisconsin-Madison z Department of Electrical and Computer Engineering, University of California San Diego Email: fzhouanfu,layla,donggua,[email protected], [email protected], [email protected] Abstract—60 GHz networks, with multi-Gbps bitrate, are Much effort has been devoted to design agile beam-steering, considered as the enabling technology for emerging applications from the hierarchical beam scanning defined in standards [1], such as wireless Virtual Reality (VR) and 4K/8K real-time [9], to heuristic-based shortcuts [10], [11] or sensing-inspired Miracast. However, user motion, and even orientation change, can cause mis-alignment between 60 GHz transceivers’ directional solutions [12], [13]. However, these methods mainly focus on beams, thus causing severe link outage. Within the practical 3D two dimensional (2D) beam-steering, e.g., assuming a phased- spaces, the combination of location and orientation dynamics array that can steer the main beam among different angles leads to exponential growth of beam searching complexity, which within a 2D plane. In practice, the users and radios move in 3D substantially exacerbates the outage and hinders fast recovery. space; and a 60 GHz array can comprise a planar “matrix” of In this paper, we first conduct an extensive measurement to analyze the impact of 3D motion on 60 GHz link performance, antenna elements, steering the beams towards different angles in the context of VR and Miracast applications.
    [Show full text]
  • Integrated Optical Phased Arrays for Beam Forming and Steering
    applied sciences Review Integrated Optical Phased Arrays for Beam Forming and Steering Yongjun Guo 1,2, Yuhao Guo 1,2, Chunshu Li 1,2, Hao Zhang 1,2, Xiaoyan Zhou 1,2 and Lin Zhang 1,2,* 1 Key Laboratory of Opto-Electronics Information Technology of Ministry of Education, School of Precision Instruments and Opto-Electronics Engineering, Tianjin University, Tianjin 300072, China; [email protected] (Y.G.); [email protected] (Y.G.); [email protected] (C.L.); [email protected] (H.Z.); [email protected] (X.Z.) 2 Key Laboratory of Integrated Opto-Electronic Technologies and Devices in Tianjin, School of Precision Instruments and Opto-Electronics Engineering, Tianjin University, Tianjin 300072, China * Correspondence: [email protected] Abstract: Integrated optical phased arrays can be used for beam shaping and steering with a small footprint, lightweight, high mechanical stability, low price, and high-yield, benefiting from the mature CMOS-compatible fabrication. This paper reviews the development of integrated optical phased arrays in recent years. The principles, building blocks, and configurations of integrated optical phased arrays for beam forming and steering are presented. Various material platforms can be used to build integrated optical phased arrays, e.g., silicon photonics platforms, III/V platforms, and III–V/silicon hybrid platforms. Integrated optical phased arrays can be implemented in the visible, near-infrared, and mid-infrared spectral ranges. The main performance parameters, such as field of view, beamwidth, sidelobe suppression, modulation speed, power consumption, scalability, and so on, are discussed in detail. Some of the typical applications of integrated optical phased arrays, such as free-space communication, light detection and ranging, imaging, and biological sensing, are shown, with future perspectives provided at the end.
    [Show full text]
  • Planar Pattern Reconfigurable Antenna Integrated with a Wifi System for Multipath Mitigation and Sustained High Definition Video
    Planar Pattern Reconfigurable Antenna Integrated With a WiFi System for Multipath Mitigation and Sustained High Definition Video Networking in a Complex EM Environment Amit Mehta1, Shivam Gautam1, Hasanga Goonesinghe1, Arpan Pal1, Rob Lewis2 and Nathan Clow3 1College of Engineering, Swansea University, Swansea, U.K. [email protected] 2BAE Systems, Chelmsford, UK 3DSTL, Fort Halstead, UK Abstract—A planer pattern reconfigurable square loop antenna integrated in a complete wireless system is presented. II. ANTENNA CONFIGURATION The antenna is designed to operate at 5 GHz WiFi band of Fig. 1 shows the top and side view of the SLA designed IEEE 802.11 ac. The antenna under electronic switching for 5 GHz WiFi band. The Antenna structure is inspired generates four tilted beams in the four space quadrants. These four beams are moved intelligently and automatically in space from [4]. The SLA has four conducting arms, each of length using a C# program for achieving and sustaining maximum 32 mm and a track width of 1.5 mm. The square loop is possible throughput. This auto beam steering is advantageous etched on top of a Rogers 4350B (ɛr=3.66, tanδ=0.009) for scenarios where a mobile user suffers from multipath substrate having a thickness of 9.6 mm and an area of 60 fading in a complex electromagnetic environment. mm × 60 mm. The entire structure is backed by a metal ground plane. The SLA is excited at the center point of each I. INTRODUCTION arm (A, B, C and D) by four vertical probes of diameter 1.3 Indoor wireless communication in 5 the GHz WiFi band of mm which are connected to the four SMA ports (A0, B0, C0 IEEE 802.11 ac is becoming popular today due to the and D0) at the bottom of the antenna.
    [Show full text]
  • Error Analysis of Programmable Metasurfaces for Beam Steering Hamidreza Taghvaee, Albert Cabellos-Aparicio, Julius Georgiou, and Sergi Abadal
    1 Error Analysis of Programmable Metasurfaces for Beam Steering Hamidreza Taghvaee, Albert Cabellos-Aparicio, Julius Georgiou, and Sergi Abadal Abstract—Recent years have seen the emergence of pro- global or local reconfigurability [16]. Further, recent years grammable metasurfaces, where the user can modify the EM re- have seen the emergence of programmable metasurfaces, this sponse of the device via software. Adding reconfigurability to the is, metasurfaces that incorporate local tunability and digital already powerful EM capabilities of metasurfaces opens the door to novel cyber-physical systems with exciting applications in do- logic to easily reconfigure the EM behavior from the outside. mains such as holography, cloaking, or wireless communications. Two main approaches have been proposed for the im- This paradigm shift, however, comes with a non-trivial increase of plementation of programmable metasurfaces, namely, (i) by the complexity of the metasurfaces that will pose new reliability interfacing the tunable elements through an external Field- challenges stemming from the need to integrate tuning, control, Programmable Gate Array (FPGA) [17], [18], or (ii) by and communication resources to implement the programmability. While metasurfaces will become prone to failures, little is known integrating sensors, control units, and actuators within the about their tolerance to errors. To bridge this gap, this paper metasurface structure [19]–[22]. examines the reliability problem in programmable metamaterials Programmable metasurfaces have opened the door to dis- by proposing an error model and a general methodology for error ruptive paradigms such as Software-Defined Metamaterials analysis. To derive the error model, the causes and potential (SDMs) and Reconfigurable Intelligent Surfaces (RISs), lead- impact of faults are identified and discussed qualitatively.
    [Show full text]
  • A Design Approach of Optical Phased Array with Low Side Lobe Level and Wide Angle Steering Range
    hv photonics Article A Design Approach of Optical Phased Array with Low Side Lobe Level and Wide Angle Steering Range Xinyu He, Tao Dong *, Jingwen He and Yue Xu State Key Laboratory of Space-Ground Integrated Information Technology, Beijing Institute of Satellite Information Engineering, Beijing 100095, China; [email protected] (X.H.); [email protected] (J.H.); [email protected] (Y.X.) * Correspondence: [email protected] Abstract: In this paper, a new design approach of optical phased array (OPA) with low side lobe level (SLL) and wide angle steering range is proposed. This approach consists of two steps. Firstly, a nonuniform antenna array is designed by optimizing the antenna spacing distribution with particle swarm optimization (PSO). Secondly, on the basis of the optimized antenna spacing distribution, PSO is further used to optimize the phase distribution of the optical antennas when the beam steers for realizing lower SLL. Based on the approach we mentioned, we design a nonuniform OPA which has 1024 optical antennas to achieve the steering range of ±60◦. When the beam steering angle is 0◦, 20◦, 30◦, 45◦ and 60◦, the SLL obtained by optimizing phase distribution is −21.35, −18.79, −17.91, −18.46 and −18.51 dB, respectively. This kind of OPA with low SLL and wide angle steering range has broad application prospects in laser communication and lidar system. Keywords: optical phased array; antenna array; low side lobe; wide angle steering range 1. Introduction Citation: He, X.; Dong, T.; He, J.; Xu, Optical phased array (OPA) is an array operating at optical frequency that achieves Y.
    [Show full text]
  • Mm-Wave Beam Steering Without In-Band Measurement
    Steering with Eyes Closed: mm-Wave Beam Steering without In-Band Measurement Thomas Nitscheyz, Adriana B. Flores∗, Edward W. Knightly∗, and Joerg Widmery yIMDEA Networks Institute, Madrid, Spain ∗ECE Department, Rice University, Houston, USA zUniv. Carlos III, Madrid, Spain Abstract—Millimeter-wave communication achieves multi- found that a mere misalignment of 18 degree reduces the link Gbps data rates via highly directional beamforming to overcome budget by around 17 dB. According to IEEE 802.11ad coding pathloss and provide the desired SNR. Unfortunately, establishing sensitivities [3], this drop can reduce the maximum throughput communication with sufficiently narrow beamwidth to obtain the necessary link budget is a high overhead procedure in which by up to 6 Gbps or break the link entirely. This misalignment is the search space scales with device mobility and the product of easily reached multiple times per second by a user holding the the sender-receiver beam resolution. In this paper, we design, device, causing substantial beam training overhead to enable implement, and experimentally evaluate Blind Beam Steering multi-Gbps throughput for mm-Wave WiFi. (BBS) a novel architecture and algorithm that removes in-band In this paper, we design, implement, and experimentally overhead for directional mm-Wave link establishment. Our sys- tem architecture couples mm-Wave and legacy 2.4/5 GHz bands evaluate Blind Beam Steering (BBS), a system to steer mm- using out-of-band direction inference to establish (overhead-free) Wave beams by replacing in-band trial-and-error testing of multi-Gbps mm-Wave communication. Further, BBS evaluates virtual sector pairs with “blind” out-of-band direction acqui- direction estimates retrieved from passively overheard 2.4/5 GHz sition.
    [Show full text]
  • High Planar Arrays and Array Feeds for Satellite Communications
    High Efficiency Planar Arrays and Array Feeds for Satellite Communications Zhenchao Yang, Kyle Browning, and Karl Warnick Department of Electrical and Computer Engineering Brigham Young University, Provo, Utah, USA [email protected], [email protected] Abstract—Limited scan range beamsteering can serve as a mechanical steered dishes. From a technical point of view, cost-effective solution for three application scenarios in satellite precisely beam steering in limited scan range plus coarse communications. Two feasible technical paths to realize the mechanical steering opens the third option for full beam steer- function are discussed in this paper. The first one is to utilize a electronically steered array feed with a conventional parabolic ing with potential lower cost and higher tracking speed and reflector. By feeding the reflector with different weights across accuracy than current barely mechanical steering, particularly the array feed, the phase distribution on the dish aperture is for multi-feed systems. There are also three common scenarios continuously shifted leading to a steered beam. Acquisition and that conventional fixed-mount dishes can not serve well. First, tracking functions can be realized economically by integrating a current dish installation demands accurate pointing. Lowering power detector based feedback system. A necessary calibration process is provided to ensure a correct indicator of signal- the accuracy requirement would increase the productivity of to-noise ratio. One dimensional bemsteering was demonstrated dish installation. Second, mount degradations caused by sag- experimentally and an improved two dimensional system is shown ging roof and weather disasters require dish re-pointing, which as well. The second path is to use a tile array with each tile costs millions of dollars in the Satcom industry.
    [Show full text]
  • Wideband Beam Steering Concept for Terahertz Time-Domain Spectroscopy: Theoretical Considerations
    sensors Article Wideband Beam Steering Concept for Terahertz Time-Domain Spectroscopy: Theoretical Considerations Xuan Liu *,† , Kevin Kolpatzeck *,† , Lars Häring, Jan C. Balzer and Andreas Czylwik Chair of Communication Systems (NTS), Faculty of Engineering, University of Duisburg-Essen (UDE), 47057 Duisburg, Germany; [email protected] (L.H.); [email protected] (J.C.B.); [email protected] (A.C.) * Correspondence: [email protected] (X.L.); [email protected] (K.K.) † These authors contributed equally to this work. Received: 3 August 2020; Accepted: 26 September 2020; Published: 28 September 2020 Abstract: Photonic true time delay beam steering on the transmitter side of terahertz time-domain spectroscopy (THz TDS) systems requires many wideband variable optical delay elements and an array of coherently driven emitters operating over a huge bandwidth. We propose driving the THz TDS system with a monolithic mode-locked laser diode (MLLD). This allows us to use integrated optical ring resonators (ORRs) whose periodic group delay spectra are aligned with the spectrum of the MLLD as variable optical delay elements. We show by simulation that a tuning range equal to one round-trip time of the MLLD is sufficient for beam steering to any elevation angle and that the loss introduced by the ORR is less than 0.1 dB. We find that the free spectral ranges (FSRs) of the ORR and the MLLD need to be matched to 0.01% so that the pulse is not significantly broadened by third-order dispersion. Furthermore, the MLLD needs to be frequency-stabilized to about 100 MHz to prevent significant phase errors in the terahertz signal.
    [Show full text]
  • The Development of Phased-Array Radar Technology the Development of Phased-Array Radar Technology
    • FENN, TEMME, DELANEY, AND COURTNEY The Development of Phased-Array Radar Technology The Development of Phased-Array Radar Technology Alan J. Fenn, Donald H. Temme, William P. Delaney, and William E. Courtney I Lincoln Laboratory has been involved in the development of phased-array radar technology since the late 1950s. Radar research activities have included theoretical analysis, application studies, hardware design, device fabrication, and system testing. Early phased-array research was centered on improving the national capability in phased-array radars. The Laboratory has developed several test-bed phased arrays, which have been used to demonstrate and evaluate components, beamforming techniques, calibration, and testing methodologies. The Laboratory has also contributed significantly in the area of phased-array antenna radiating elements, phase-shifter technology, solid-state transmit-and- receive modules, and monolithic microwave integrated circuit (MMIC) technology. A number of developmental phased-array radar systems have resulted from this research, as discussed in other articles in this issue. A wide variety of processing techniques and system components have also been developed. This article provides an overview of more than forty years of this phased-array radar research activity. was certainly affordable array radar with thousands of array ele- not new when Lincoln Laboratory’s phased- ments, all working in tightly orchestrated phase co- Tarray radar development began around 1958. herence, would not be built for a very long time. In Early radio transmitters and the early World War II retrospect, both the enthusiasts and the skeptics were radars used multiple radiating elements to achieve de- right. The dream of electronic beam movement was sired antenna radiation patterns.
    [Show full text]
  • Beam-Forecast: Facilitating Mobile 60 Ghz Networks Via Model-Driven Beam Steering Anfu Zhou∗ Xinyu Zhang† Huadong Ma∗ ∗ Beijing Key Lab of Intell
    IEEE INFOCOM 2017 - IEEE Conference on Computer Communications Beam-forecast: Facilitating Mobile 60 GHz Networks via Model-driven Beam Steering Anfu Zhou∗ Xinyu Zhang† Huadong Ma∗ ∗ Beijing Key Lab of Intell. Telecomm. Software and Multimedia, Beijing University of Posts and Telecomm. † University of Wisconsin-Madison Email: [email protected], [email protected], [email protected] Abstract—Low robustness under mobility is the Achilles’ heel of 60 GHz radios: (i) High directionality. 60 GHz radios of the emerging 60 GHz networking technology. Instead of using face much stronger attenuation than existing Wi-Fi (26dB and omni-directional antennas as in existing Wi-Fi/cellular networks, 21.6dB worse when compared with 2.4 GHz and 5 GHz WiFi, 60 GHz radios communicate via highly-directional links formed by phased-array beam-forming, so as to upgrade wireless link respectively [10]). To remedy such strong attenuation, 60 GHz throughput to multi-Gbps. However, user motion causes misalign- radios employ phased-array antennas to form highly directional ment between the Tx’s and Rx’s beam directions, and often leads beams. But high directionality results in high vulnerability to to link outage. Legacy 60 GHz protocols realign the beams by mobility — whenever the Tx/Rx moves, their beam directions scanning alternative Tx/Rx beams. But unfortunately this tedious may become misaligned, causing high risk of link outage. (ii) process can easily overwhelm the useful channel time, leaving the Tx/Rx in misalignment most of the time during mobility. In this Channel sparsity. As reported widely by existing work [11]– paper, we propose Beam-forecast, a novel model-driven beam [14], the 60 GHz spatial channel profile (SCP) is extremely steering approach that can sustain high performance for mobile sparse, i.e., the Tx can reach the Rx only through a small 60 GHz links.
    [Show full text]
  • Using Steerable Beam Directional Antenna for Vehicular Network Access
    MobiSteer: Using Steerable Beam Directional Antenna for Vehicular Network Access Vishnu Navda1, Anand Prabhu Subramanian1 , Kannan Dhanasekaran1 , Andreas Timm-Giel2, Samir R. Das1 1 Computer Science Department, Stony Brook University, Stony Brook, NY 11794, U.S.A. 2 University of Bremen, TZI, Communication Networks, 28334 Bremen, Germany ABSTRACT In this work, we investigate the use of directional anten- nas and beam steering techniques to improve performance of 802.11 links in the context of communication between a moving vehicle and roadside APs. To this end, we develop a framework called MobiSteer that provides practical ap- proaches to perform beam steering. MobiSteer can operate in two modes { cached mode { where it uses prior radio survey data collected during \idle" drives, and online mode, where it uses probing. The goal is to select the best AP and beam combination at each point along the drive given the available information, so that the throughput can be maxi- mized. For the cached mode, an optimal algorithm for AP and beam selection is developed that factors in all overheads. We provide extensive experimental results using a com- mercially available eight element phased-array antenna. In the experiments, we use controlled scenarios with our own APs, in two different multipath environments, as well as in Figure 1: Beam steering and AP selection to im- situ scenarios, where we use APs already deployed in an ur- prove connectivity. ban region { to demonstrate the performance advantage of using MobiSteer over using an equivalent omni-directional antenna. We show that MobiSteer improves the connec- Keywords tivity duration as well as PHY-layer data rate due to bet- Steerable Beam, Phased-array Antenna, Vehicular Internet ter SNR provisioning.
    [Show full text]
  • Antenna Beam Steering and Beam Forming at Mm-Wave and Thz Frequencies
    Antenna beam steering and beam forming at mm-Wave and THz frequencies Master Thesis submitted to the Faculty of the Escola T`ecnicad'Enginyeria de Telecomunicaci´ode Barcelona Universitat Polit`ecnicade Catalunya by Sara Vega Pi~na In partial fulfillment of the requirements for the master in TELECOMMUNICATIONS ENGINEERING Advisor: Mar´ıaConcepci´onSantos Co-Advisor: Daniel Nu~no Barcelona, January 20th, 2021 Contents List of Figures4 List of Tables6 1 Introduction8 2 Photonic Antenna Control 10 2.1 Phased Array Antennas Beam forming...................... 10 2.2 Photoconductive Antennas for THz Radiation.................. 11 3 Optical TTD Network 14 3.1 Multiwavelength Beam Steering Network.................... 14 3.1.1 Effect of compensating delays...................... 15 3.1.2 Geometrical Delays............................ 16 3.1.3 Dispersive Delays............................ 18 3.1.4 Maximum beam steered angle...................... 19 3.2 CD-fading control................................. 20 3.3 OTTDN Simulations............................... 23 4 TeraHertz Systems 26 4.1 Definition of THz systems simulation methodology............... 26 4.1.1 Time-Domain simulation of PCAs (Primary fields)........... 26 4.1.2 Time-Domain simulation of Lens-coupled PCAs (Secondary fields).. 32 4.2 Validation of THz Simulation Methodology................... 35 4.2.1 PCAs modeling.............................. 35 4.2.2 Lens approach.............................. 36 4.2.3 Primary fields............................... 38 4.2.4 Secondary fields............................. 38 4.3 Simulation and measurement of THz systems.................. 40 4.3.1 Fractal structures characteristics..................... 40 4.3.2 Modeling of Sierpinski Fractal structures for THz radiation....... 40 4.3.3 Simulation of THz Far Fields with Sierpinski structures......... 44 4.4 Terahertz Beam Steering............................. 49 5 Conclusions and future development 52 References 54 Appendices 59 A Matlab Codes 59 A.1 VPI Radiation Pattern .mat file.........................
    [Show full text]