DIAGNOSTICS OF THE STOCHASTIC IONOSPHERIC CHANNEL IN THE DECAMETER BAND OF RADIO WAVES

We propose a method for direct diagnostics of a stochastic ionospheric radio channel. This method can recalculate probe signal characteristics into transmitted signal characteristics. We derive analytical equations of second-order statistical moments for trajectory characteristics of the main and probe signals propagating in a three-dimensional randomly inhomogeneous ionosphere. We take into account boundary conditions at signal transmission and reception points. As a model of random irregularities of permittivity of the ionosphere, we utilize the concept of a changing space-time correlation ellipsoid, which is self-consistent with spatial changes in the average ionosphere. Time fluctuations of random irregularities are taken into account by the hypothesis of frozen transfer. We use analytical relationships to calculate the expected statistical characteristics of decameter signals along oblique probing paths of the ionosphere. An operational numerical algorithmization of the formulas derived is proposed. We report results of numerical experiments to determine the expected phase variances, group delay, and Doppler frequency shift of the main signal on a given single-hop path, based on measurements of these characteristics of a probe signal on a secondary path. We demonstrate the efficiency of the proposed method for diagnosing statistical trajectory characteristics of a decameter signal along single-hop paths under conditions when ground points of transmission and reception of the main and probe signals are outside the vicinity of focusing points of the wave field.

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Statistical characteristics of Doppler-frequency background oscillations of short radio waves with periods of from 1 to 200 sec

Radiophysics and Quantum Electronics ◽

10.1007/bf01041790 ◽

1993 ◽

Vol 35 (6-7) ◽

pp. 391-393

Author(s):

�. B. Andabaev ◽

V. M. Krasnov ◽

G. M. Pelenitsyn ◽

O. E. Ryaskov ◽

N. M. Salikhov

Keyword(s):

Doppler Frequency ◽

Statistical Characteristics ◽

Radio Waves

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Analysis of Non-Stationarity for 5.9 GHz Channel in Multiple Vehicle-to-Vehicle Scenarios

Sensors ◽

10.3390/s21113626 ◽

2021 ◽

Vol 21 (11) ◽

pp. 3626

Author(s):

Fang Li ◽

Wei Chen ◽

Yishui Shui

Keyword(s):

Transmission Rate ◽

Radio Channel ◽

Vertical Direction ◽

Statistical Characteristics ◽

Small Scale ◽

Delay Spread ◽

Important Indicator ◽

Power Delay Profile ◽

Channel Characteristics ◽

Vehicle To Vehicle

The vehicle-to-vehicle (V2V) radio channel is non-stationary due to the rapid movement of vehicles. However, the stationarity of the V2V channels is an important indicator of the V2V channel characteristics. Therefore, we analyzed the non-stationarity of V2V radio channels using the local region of stationarity (LRS). We selected seven scenarios, including three directions of travel, i.e., in the same, vertical, and opposite directions, and different speeds and environments in a similar driving direction. The power delay profile (PDP) and LRS were estimated from the measured channel impulse responses. The results show that the most important influences on the stationary times are the direction and the speed of the vehicles. The average stationary times for driving in the same direction range from 0.3207 to 1.9419 s, the average stationary times for driving in the vertical direction are 0.0359–0.1348 s, and those for driving in the opposite direction are 0.0041–0.0103 s. These results are meaningful for the analysis of the statistical characteristics of the V2V channel, such as the delay spread and Doppler spread. Small-scale fading based on the stationary times affects the quality of signals transmitted in the V2V channel, including the information transmission rate and the information error code rate.

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A Field Measurement Based Wind Characteristics Analysis of a Typhoon in Near-Ground Boundary Layer

Atmosphere ◽

10.3390/atmos12070873 ◽

2021 ◽

Vol 12 (7) ◽

pp. 873

Author(s):

Dandan Xia ◽

Liming Dai ◽

Li Lin ◽

Huaifeng Wang ◽

Haitao Hu

Keyword(s):

Turbulence Intensity ◽

Field Measurement ◽

Three Dimensional ◽

Wind Data ◽

Statistical Characteristics ◽

Gust Factor ◽

Characteristics Analysis ◽

Wind Characteristics ◽

The Mean ◽

The Relationship

The field measurement was conducted to observe the wind field data of West Pacific typhoon “Maria” in this research. With the application of ultrasonic anemometers installed in different heights (10 m, 80 m, 100 m) of the tower, the three dimensional wind speed data of typhoon “Maria” was acquired. In addition, vane-type anemometers were installed to validate the accuracy of the wind data from ultrasonic anemometers. Wind characteristics such as the mean wind profile, turbulence intensity, integral length scale, and wind spectrum are studied in detail using the collected wind data. The relationship between the gust factor and turbulence intensity was also studied and compared with the existing literature to demonstrate the characteristics of Maria. The statistical characteristics of the turbulence intensity and gust factor are presented. The corresponding conclusion remarks are expected to provide a useful reference for designing wind-resistant buildings and structures.

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A comparison of the results of a numerical simulation and an approximate calculation of the statistical characteristics of radio waves in a layer with random inhomogeneities of dielectric permittivity

Waves in Random Media ◽

10.1088/0959-7174/11/4/301 ◽

2001 ◽

Vol 11 (4) ◽

pp. 363-376 ◽

Cited By ~ 2

Author(s):

N T Afanasiev ◽

S N Kolesnik ◽

M V Tinin

Keyword(s):

Numerical Simulation ◽

Dielectric Permittivity ◽

Approximate Calculation ◽

Statistical Characteristics ◽

Radio Waves ◽

Comparison Of The Results

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Statistical characteristics of scattered waves in three-dimensional random media: comparison of the finite difference simulation and statistical methods

Geophysical Journal International ◽

10.1093/gji/ggy298 ◽

2018 ◽

Vol 215 (1) ◽

pp. 585-599 ◽

Cited By ~ 2

Author(s):

Kentaro Emoto ◽

Haruo Sato

Keyword(s):

Finite Difference ◽

Statistical Methods ◽

Random Media ◽

Three Dimensional ◽

Statistical Characteristics ◽

Media Comparison

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Invisible Encryption Communication Method based on WFRFT

10.21203/rs.3.rs-173299/v1 ◽

2021 ◽

Author(s):

Fang Liu ◽

Lizhi Chen ◽

Yongxin Feng

Keyword(s):

Fractional Fourier Transform ◽

Signal Transmission ◽

Single Parameter ◽

Communication Process ◽

Statistical Characteristics ◽

Control Rules ◽

Communication Method ◽

Micro Features ◽

Encryption Method ◽

Technical Basis

Abstract Considering that the open signal transmission mode can lead to the potential risk of interception, identification, decoding, and interference, high confidentiality is imperative for wireless communication. The security of communication process is typically ensured by encrypting and concealing transmitted information. The weighted fractional Fourier transform (WFRFT) technology can substantially change the signal characteristics, and the statistical characteristics of the signal diversify to effectively hide the communication information. In this paper, considering a single parameter-WFRFT as the breakthrough point, the in-depth investigation of the mechanism of a single-parameter fractional domain and the analysis of its potential micro-features and dark features are presented; accordingly, an invisible encryption method with vector jumping is proposed. The relationship between modulation order and constellation diagram is utilized, the jumping matrix and vector are thereafter established, and the control rules are formulated accordingly; furthermore, the dynamic modulation order is obtained by the jumping vector control. The new method can improve the security performance of the system and provide a technical basis for securing communication with anti-jamming, anti-interception, and anti-deception capability.

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A Statistical Channel Model for Stochastic Antenna Inclination Angles

International Journal of Antennas and Propagation ◽

10.1155/2019/3487149 ◽

2019 ◽

Vol 2019 ◽

pp. 1-12

Author(s):

Gang Liu ◽

Ming Zhang ◽

Yaming Bo

Keyword(s):

Indoor Environment ◽

Channel Model ◽

Three Dimensional ◽

Statistical Characteristics ◽

Line Of Sight ◽

Static State ◽

Inclination Angles ◽

Short Time ◽

Tracing Method ◽

Non Line Of Sight

The actions of a person holding a mobile device are not a static state but can be considered as a stochastic process since users can change the way they hold the device very frequently in a short time. The change in antenna inclination angles with the random actions will result in varied received signal intensity. However, very few studies and conventional channel models have been performed to capture the features. In this paper, the relationships between the statistical characteristics of the electric field and the antenna inclination angles are investigated and modeled based on a three-dimensional (3D) fast ray-tracing method considering both the diffraction and reflections, and the radiation patterns of an antenna with arbitrary inclination angles are deducted and included in the method. Two different conditions of the line-of-sight (LOS) and non-line-of-sight (NLOS) in the indoor environment are discussed. Furthermore, based on the statistical analysis, a semiempirical probability density function of antenna inclination angles is presented. Finally, a novel statistical channel model for stochastic antenna inclination angles is proposed, and the ergodic channel capacity is analyzed.

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Time-Frequency Characteristics of In-Home Radio Channels Influenced by Activities of the Home Occupant

Sensors ◽

10.3390/s19163557 ◽

2019 ◽

Vol 19 (16) ◽

pp. 3557

Author(s):

Alireza Borhani ◽

Matthias Pätzold ◽

Kun Yang

Keyword(s):

Radio Channel ◽

Wearable Sensors ◽

Fall Detection ◽

The Body ◽

Home Healthcare ◽

Radio Waves ◽

Time Frequency ◽

Daily Life Activities ◽

Data Files ◽

The Impact

While aging is a serious global concern, in-home healthcare monitoring solutions are limited to context-aware systems and wearable sensors, which may easily be forgotten or ignored for privacy and comfort reasons. An emerging non-wearable fall detection approach is based on processing radio waves reflected off the body, who has no active interaction with the system. This paper reports on an indoor radio channel measurement campaign at 5.9 GHz, which has been conducted to study the impact of fall incidents and some daily life activities on the temporal and spectral properties of the indoor channel under both line-of-sight (LOS) and obstructed-LOS (OLOS) propagation conditions. The time-frequency characteristic of the channel has been thoroughly investigated by spectrogram analysis. Studying the instantaneous Doppler characteristics shows that the Doppler spread ignores small variations of the channel (especially under OLOS conditions), but highlights coarse ones caused by falls. The channel properties studied in this paper can be considered to be new useful metrics for the design of reliable fall detection algorithms. We share all measured data files with the community through Code Ocean. The data can be used for validating a new class of channel models aiming at the design of smart activity recognition systems via a software-based approach.

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