Angle Of Departure Research Articles

On the Capacity and State Estimation Error of “Beam-Pointing” Channels: The Binary Case

Motivated by beamformed millimeter-wave (mmWave) communication, we consider the optimal tradeoff between reliable communication rate and state estimation error for a new state-dependent channel model with in-block memory referred to as the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">binary beam-pointing</i> (BBP) channel. The multiantenna base station (BS) uses a finite beamforming codebook (i.e., discrete beam directions) and associates the target user to the most favorable beam, i.e., the beam directed along the strongest propagation path from BS to the user in 5G and IEEE 802.11ad mmWave communication systems. We model the target user’s Angle-of-Departure (AoD) as the state of a state-dependent channel. Since the AoD remains almost constant over several consecutive time slots, the channel has memory. In addition, we assume the BS receives implicit causal feedback (e.g., modeling a backscatter signal as in radar) and consider a joint communication and sensing (JCAS) problem where the BS is also interested in <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">explicitly</i> estimate the channel state (quantized AoD). We derive a closed-form solution to the capacity of the BBP channel model under the peak input cost constraint. Under the average constraint, we present an implicit capacity result, where the capacity is given as the solution of an optimization problem, and we provide an algorithm for its numerical computation. Finally, for the JCAS problem at hand, we provide the minimum distortion under the peak input constraint and show that this coincides with that obtained by the capacity-achieving strategy. This <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">completely characterizes the capacity-distortion tradeoff</i> for the BBP channel under peak input constraint. For the average constraint case, numerical results show that our capacity-achieving strategy yields a state estimation error very close to the theoretical minimum, showing the near-optimality of the proposed strategy for the JCAS problem under the average cost constraint.

Variance state propagation for uplink channel estimation in LEO satellite systems

AbstractThis paper, considers the channel estimation problem of the uplink low Earth orbit (LEO) satellite orthogonal frequency division multiplexing (OFDM) system. By exploiting the channel structured sparsity in the delay‐Doppler‐angle domain, the channel estimation problem is formulated as a block‐sparse signal recovery problem. The variance state propagation (VSP) framework is extended to solve such a problem. Considering that the delay, Doppler shift, and angle of departure (AoD) of each propagation path may not exactly fall on the presumed discrete grid points, an expectation maximization (EM) based parameter learning scheme in VSP to iteratively update the grid parameters is introduced. Simulation results demonstrate that the proposed approach achieves a substantial performance gain over the existing methods.

Sub-Array-Based Millimeter Wave Massive MIMO Channel Estimation

Combination of millimeter wave (mmWave) and massive multiple input multiple output (MIMO) forms a promising technology for future sixth generation networks. As the number of antennas increases, propagation channel starts yielding spherical wavefronts, for which the traditional channel estimation algorithms are no longer applicable. To overcome this technical gap, a novel MIMO channel estimation scheme based on the assumption of spherical wavefront is proposed in this work. The large antenna array is first divided into several sub-arrays, and then the channel estimation is performed for each sub-array based on the orthogonal matching pursuit algorithm. In addition, the joint estimation of angle of arrivals and departures (AoAs and AoDs) of each uniform planar sub-array is transformed into separate estimation by dimensionality reduction. Next, an iterative estimation is performed using Taylor expansion to continuously approximate the real grid points to recover the AoAs/AoDs. Lastly, the superiority of the proposed algorithm is verified by numerical simulations, where the proposed algorithm exhibits the best NMSE performance, compared with the existing MIMO channel estimation methods.

Flow Field Simulations Over Reentry Modules at High Speed

Reentry capsule configurations significantly differ from each other due to entry conditions and mission requirements. This paper describes numerical simulations of the viscous flow over the Beagle and the OREX (Orbital Reentry EXperiments) configurations for freestream Mach numbers in the range of 1.2 - 5.0. The flow fields over the reentry modules are obtained by solving time-dependent axisymmetric compressible laminar Navier-Stokes equations. The fluid mechanics equations are discretized in spatial coordinates employing a finite volume method, which reduces the governing equations to semi-discretized ordinary differential equations. Temporal integration is carried out using a two-stage Runge-Kutta time-stepping scheme. A local time-stepping is employed to get the steady state solution. The numerical simulation is performed on a single-block structured grid. The flow field features around the reentry capsules such as bow shock wave, sonic line, expansion fan and recirculation flow in the base-shell region are well captured by the present numerical computation. The effects of the geometrical parameters of the module, such as aspect ratio, frontal segment bluntness, fore body cone angle and shoulder rounding radius on the wake throat width, distance from the wake throat to the base of the model, flow departure angle and aerodynamic drag are analyzed using the numerically simulated flow field.

3D geometry‐based UAV to vehicle multiple‐input multiple‐output channel model incorporating Unmanned aerial vehicle heaving motion

AbstractUnmanned aerial vehicles (UAVs) play a vital role in the beyond fifth‐generation (B5G) and sixth‐generation (6G) wireless communication scenarios. This paper proposes a non‐stationary three‐dimensional (3D) geometry‐based multiple‐input multiple‐output channel model for UAV to vehicle (U2V) communications considering UAV heaving motion. The proposed model incorporates the effects of UAV heaving along with the rotation, acceleration, and 3D velocity variation for matching the realistic U2V communication scenarios. The computation methods for time variant channel parameters such as Doppler frequencies, angle of arrival, and angle of departure are given and analysed. The theoretical and statistical properties, including spatial temporal correlation function, TCF, level crossing rate, average fade duration, and Doppler power spectral density are derived and analysed aiming to evaluate the proposed model. Simulation results show that the output statistical characteristics agree with the hypothetical and simulated outcomes, which shows the validity of both the channel model and theoretical derivations.The cover image is based on the Research Article 3D geometry‐based UAV to vehicle multiple‐input multiple‐output channel model incorporating Unmanned aerial vehicle heaving motion by Naeem Ahmed et al., https://doi.org/10.1049/mia2.12393

Deviated Saccadic Trajectory as a Biometric Signature of Glaucoma.

To investigate whether the trajectories of saccadic eye movements (SEMs) significantly differ between glaucoma patients and controls. SEMs were recorded by video-based infrared oculography in 53 patients with glaucoma and 41 age-matched controls. Participants were asked to bilaterally view 24°-horizontal, 14°-vertical, and 20°-diagonal eccentric Goldmann III-sized stimuli. SEMs were evaluated with respect to the saccadic reaction time (SRT), the mean velocity, amplitude, and two novel measures: departure angle (DA) and arrival angle (AA). These parameters were compared between the groups and the associations of SEM parameters with glaucoma parameters and integrated visual field defects were investigated. Glaucoma patients exhibited increased mean SRT, DA, and AA values compared with controls for 14°-vertical visual targets (P = 0.05, P < 0.01, and P < 0.01, respectively). The SRT, DA, and AA were significantly associated with the mean and pattern standard deviations of perimetry and with the mean RNFL thickness by OCT (all P < 0.001). Glaucoma was associated with the AA (P = 0.05) and both the SRT (P = 0.01) and DA (P = 0.04) were associated with integrated visual field defects. The saccadic trajectories of glaucoma patients depart in an erroneous path and compensate the disparity by deviating the trajectory at arrival. The initial deviation that we observed (despite continuous exposure to the stimulus) suggests the disoriented spatial perception of glaucoma patients which may be relevant to difficulties encountered daily.

Features of Forecasting the Operation of Ionospheric Radio Lines in Upper Rays Modes

The frequency dependence of transmitted information qualitative indicators is analyzed on theexample of two meridional radio links: single-hop (~2600 km) and dominant two-hop (~5100 km) for basicmodes of radio wave propagation in the ionosphere. It is shown that the presence of highly efficient receivingtransmittingantennas in a radio communication system leads to the need to take the existence of a priori energeticallyextremely weak modes into account in the problem of radio path specification statement. In thiscase, we consider those formed exclusively by the mechanism of radiation transfer along the upper-angles raytrajectories in the ionospheric propagation of radio waves. If the angles of departure and arrival for suchmodes and the directions of the main lobes of the antenna patterns at the end points of the radio path coincide,the signal-to-noise ratio for the wave field can reach the required threshold value and ensure the successfuloperation of the radio communication system. This may expand the upper frequency limit for the passageof radio waves in the transition regions of jump propagation of radio waves in the ionosphere; it shouldbe taken into account in forecasting the operation of ionospheric radio links.

Intelligent Omni-Surfaces Aided Wireless Communications: Does the Reciprocity Hold?

Intelligent omni-surfaces (IOS) have attracted great attention recently due to its potential to achieve full-dimensional communications by simultaneously reflecting and refracting signals toward both sides of the surface. However, it still remains an open question whether the reciprocity holds between the uplink and downlink channels in the IOS-aided wireless communications. In this work, we first present a physics-compliant IOS-related channel model, based on which the channel reciprocity is investigated. We then demonstrate the angle-dependent electromagnetic response of the IOS element in terms of both incident and departure angles. This serves as the key feature of IOS that drives our analytical results on beam non-reciprocity. Finally, simulation and experimental results are provided to verify our theoretical analyses.

Utilizing Attitude Information for Efficient Multi-User Millimeter-Wave Communications

Sensing has played an important role in the 5G wireless network. It is well recognized that the energy efficiency of mobile devices can be further improved with the assistance of sensing. As an important sensing resource, attitude information is highly related to the angle of arrivals (AoAs) information when user equipments (UEs) rotate. It provides great potential to improve transceiver designs for multi-user millimeter-wave (mmWave) green communications. In this paper, we propose an attitude information aided block diagonalization receiver design algorithm. We first adopt angle of departure aided block diagonalization (AoD-BD) to eliminate inter-user interference (IUI). Then we compensate the rotation for each UE by only updating the receiver with attitude information from motion sensors. Compared to the joint transceiver design performance, we have theoretically proved that the sum spectral efficiency performance penalty of keeping transmitter unchanged is generally negligible. Furthermore, we consider the effect of imperfect attitude information, and derive a robust receiver by modeling the measurement error as Gaussian. Finally, the simulation results are presented to verify the effectiveness of the proposed design. It is noted that no feedback is required between the base station (BS) and UE during the rotation, which substantially reduces the system overhead.

BLOOD SUPPLING THE TESTICLES IN FERTILE PERIOD OF HUMAN’S LIFE

In work, the sources of blood supply to the testicle on the way to its moving from the abdominal cavity to the scrotum during the fertile period of a person were investigated. A comparative anatomical assessment of the blood supply to the testicles of some mammals in different periods of their sexual development is also provided. The functional disorders in the human endocrine system at the stages of puberty after the determination of blood hormones were described. On the basis of morphological studies carried out on fetus, variants of the departure of the testicular artery and percentage variants of branching of this artery on the trunk were established. As a result of the study, the largest increase in the diameter of the testicular artery up to 0.7 mm was determined from the 5th to the 7th month of the fertile period of a human’s life, as the variability of the angle of departure of the testicular arteria from the main vessel. Options for branching the testicular artery into distributive and mixed groups are also proposed. The detailed morphological study of the intra-organ bed of the testicle, as a tubular organ, as well as the vessels that blood to the organs surrounding the testicles: epididymes, vas deferens, provides results of the work. In the work, the effect of ligation vessels of the testicle, epididimes and vas deferens on the structure and function of the organs that provide blood supply, the author also investigated. In the course of the experiment, it was proven that cutting the testicular arteries in not sexually immature animals lends to greater destruction of the seminiferous tubules than their ligation in sexually mature animals. As a result of the experiment, the author proposed practical recommendations for operations on the testicles. In particular, to determine of the sectional level of the main feeding vessel responsibility to variants and groups of branching testicular arteries.

Statistical channel model for 6G communication networks in Banda Aceh City

Wireless technology is expected to undergo considerable transformation because of the numerous services offered by 6G communication networks, which virtually entirely encompass every part of everyday life and use a variety of devices. Channel modeling is an essential factor in designing 6G communication networks. To meet the channel requirements of future 6G communication networks, it is crucial to measure the channel to consider path loss, multi-band, fading, blocking effect, multipath clustering, transmitter, and receiver moving speed/direction/time. The goal of this paper is to design and evaluate a 6G communication network in Banda Aceh City using a statistical channel model. The channel model is associated with environmental conditions such as rainfall and humidity. The method is then based on computer simulation using the NYUSIM simulator to complete the channel modeling using an operating frequency of 95 GHz with a bandwidth of 800 MHz. In the simulator, the designed 6G channel model is evaluated in both line-of-sight (LOS) and non-line-of-sight (NLOS) network environments. In addition, the designated network parameters, such as the coverage area, angle of arrival (AoA), angle of departure (AoD), and power delay profile (PDP), are simulated. The results, at AoA, the value of received power for LOS conditions ranges from -86 dBm to -101 dBm, while the value for NLOS conditions ranges from -91 dBm to -111 dBm. Under LOS conditions, the received power for AoD ranges from -86 dBm to -101 dBm, whereas under NLOS conditions, it ranges from -91 dBm to -111 dBm. In the omnidirectional PDP, the pathloss value for the LOS condition is 99.8 dB and the delay is 17.9 ns, while the pathloss value for the NLOS condition is 104.2 dB with a delay of 28.1 ns. For the directional PDP, the LOS condition yields a path loss of 106.4 dB and a delay of 2.9 ns, while the NLOS condition yields a path loss of 110.5 dB and a delay of 3 ns. Conclusions. The simulation indicated that the AoA, AoD, and PDP in terms of received power, pathloss, and propagation delay are in acceptable conditions for a 6G network in Banda Aceh City in the two observed environments. Therefore, it is conceivable to establish a 6G network in Banda Aceh City in the future.

Theoretical substantiation of the design parameters of the rotating reflective cone of the sprinkler nozzle, providing increased wind resistance of rain

The article deals with the theoretical question of substantiating the design parameters of a rotating deflector cone providing the creation of a rain cloud with increased wind resistance. The optimal geometric parameters of the rotating deflector cone are determined. The results of laboratory studies are presented, during which the effect of changing the angle of departure of a raindrop descending from a rotating deflector cone on the amount of rain loss on evaporation and wind drift, as well as the irrigation radius, was investigated. It has been found that the use of sprinkler nozzles with a rotating deflector cone can increase the wind resistance of the rain created while maintaining the irrigation radius and reduce water loss by evaporation up to 9.8% compared with rain nozzles with a non-rotating smooth deflector cone.

Beam-Tracking Technique for IRS-Assisted mmWave Cellular Systems With Uniform Planar Array

In this paper, a beam-tracking technique is proposed for millimeter-wave (mmWave) cellular systems with an intelligent reflective surface (IRS). A preamble design technique for IRS-assisted cellular systems is proposed using the complex conjugate property of the Zadoff-Chu sequence and reflecting nature of IRS. Moreover, a beam-tracking technique for mmWave cellular systems with a uniform planar array (UPA) is also proposed to track the variation in the angle of departure (AoD) using subpanel structures of the UPA. Through simulation, it is demonstrated that the beam tracking technique with the proposed preamble can successfully track 2-D AoD trajectories of the base station and IRS.

Radio Channel Measurements and Characterization in Substation Scenarios for Power Grid Internet of Things

Wireless communication technologies play a key role to support the implementation of power grid Internet of Things (PIoT). An in-depth knowledge of the radio channel is vital to the application of wireless communication technologies in PIoT. This paper investigates the radio channel measurements and characterization for PIoT substation scenarios. A novel channel sounder is designed for achieving omnidirectional measurements and phased array antennas based directional measurements, and a directional multipath components extraction algorithm is proposed. The channel sounding system is verified and is used to perform a series of 3.35 GHz omnidirectional and directional channel measurements in four substation scenarios, involving a 10 kV switch room, a 110 kV GIS room, a semi-indoor 110 kV substation and an outdoor 220 kV substation. Based on the measured channel impulse responses data, both large-scale and small-scale fading characteristics of substation channels are extracted and analyzed. Empirical models of path loss, shadow fading, Ricean K-factor and root-mean-square (RMS) delay spread are proposed. In addition, results of RMS angle spread of departure and RMS angle spread of arrival are presented. These results will provide useful reference for the deployment and optimization of wireless communication networks in PIoT substation scenarios.

High-Performance Channel Estimation for mmWave Wideband Systems With Hybrid Structures

In this paper, a channel estimation problem for millimeter-wave (mmWave) multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) systems with hybrid structures is studied. Firstly, a beamspace multiple signal classification (MUSIC) algorithm for mmWave wideband channels is proposed to simultaneously estimate the angles of arrival (AOAs), angles of departure (AODs) and transmission delays. Since the traditional spectral peak search method has high complexity, a multi-spectral peak search method is skillfully designed to search for multiple spectral peaks on the MUSIC spatial spectrum more quickly and accurately. Then, the proposed channel estimator is extended to more actual systems equipped with uniform planar arrays (UPAs). Finally, the Cramér–Rao bound (CRB) results of these channel parameters are derived for evaluating the performance of the proposed channel parameter estimator. Simulation results demonstrate that the proposed channel estimator has greatly high channel estimation accuracy.

ASSESSMENT OF THE STABILITY OF MOTION OF A WHEEL SEMI-TRACK UNIT

The paper analyzes the influence of the geometric parameters of the semi-trailer unit on the stability of its movement. A mathematical model of the dynamics of the cultivator unit under the influence of disturbing forces is developed. The analysis of research results shows that in the process of movement, the wheeled semi-trailer unit is subjected to transverse forces, which arise as a result of the unevenness of the traction resistance of the side and rear beams. The main vector and the main moment cause the unit to deviate from the rectilinear movement. The differential equations obtained in the work make it possible to determine the values of the lead angles, their components, and the speed at which the lead of the unit will be the smallest. Based on the dependence of the angle of departure of the unit on the disturbing forces and speed of movement, the optimal location of the side bars of the semi-trailer unit on the tractor frame was found.

Spatial Signal Design for Positioning via End-to-End Learning

This letter considers the problem of end-to-end (E2E) learning for joint optimization of transmitter precoding and receiver processing for mmWave downlink positioning. Considering a multiple-input single-output (MISO) scenario, we propose a novel autoencoder (AE) architecture to estimate user equipment (UE) position with multiple base stations (BSs) and demonstrate that E2E learning can match model-based design, both for angle-of-departure (AoD) and position estimation, under ideal conditions without model deficits and outperform it in the presence of hardware impairments.

The impact of particular exercises according to the fluidity of kinetic transfer for some variables Biomechanics for the moment of upgrading and the achievement of a long jump of the talented

The research contained introduction, problem, hypotheses and objectives, as it touched upon the impact of particular exercises according to the fluidity of kinetic transfer on some biomechanical variables at the moment of upgrading for the research sample from the talented long-jumpers . As the research touched on the stages of the smooth transport motion the penultimate step and the last step of the speed. And the starting speed of the body, the angle of departure, the fluidity of motion, the kinetic transfer and the achievement of the sample members. Where the results for the control and experimental groups and the relationship that took place according to the kinetic transfer fluidity of the particular exercises that the researchers used in the study variables. The researchers also reached the results of the control and experimental groups in the variables of the study in the achievement of the sample members in the impact of these particular exercises and what they reached in the pre and posttest of the sample members. The research concluded that the use of such exercises operatively affected according to the fluidity of the kinetic transfer of the biomechanical variables and the achievement of the sample members.

Double-Layer Precoder and Cluster-Based Power Allocation Design for LEO Satellite Communication With Massive MIMO

In this work, we propose a double-layer precoder and cluster-based power allocation design for low earth orbit (LEO) satellite communication with massive multiple input multiple output (MIMO). Specifically, spectral efficiency (SE) is chosen as the evaluation metric with hardware complexity, transmit power, instantaneous channel state information (iCSI) and statistical channel state information (sCSI) considered. We simplify the three-dimension (3D) air-to-ground MIMO channel under satellite environment with the angular spread model. Then, a double-layer precoder is proposed to reduce the hardware complexity and eliminate the inter-user interference (IUI) among each user cluster. With angle of departure (AoD) information, the user clustering criteria to maximize the SE and eliminate inter-cluster interference (ICI) is derived. After that, a cluster-based power allocation scheme is proposed by dividing the total transmit power into two parts, one to meet the user’s minimum service requirement and the other to get optimal SE performance by waterfilling algorithm. Simulation results show that the proposed scheme achieves better SE performance compared with other feasible approaches.

Channel Reconstruction-Aided MUSIC Algorithms for Joint AoA&amp;AoD Estimation in MIMO Systems

This letter discusses the issue of joint angle-of-arrival (AoA) and angle-of-departure (AoD) estimation for multi-input multi-output (MIMO) arrays, so as to conceive a novel one-snapshot multiple signal classification (MUSIC)-derived algorithm based on channel reconstruction therein. Compared to conventional two-dimensional MUSIC (2D-MUSIC), not only does the proposed algorithm avoid the problem of matrix rank deficit, but it also brings a prominent complexity reduction yet achieving satisfactory accuracy. Simulation results verify the utility and advancement of our algorithm, especially in the scheme with high real-time requirements.