Measurements of small-scale fading and path loss for long range RF tags

2003 ◽  
Vol 51 (8) ◽  
pp. 1740-1749 ◽  
Author(s):  
Daeyoung Kim ◽  
M.A. Ingram ◽  
W.W. Smith
Keyword(s):  
Long Range ◽  
Path Loss ◽  
Small Scale ◽  
Rf Tags

scholarly journals Analysis of Propagation Characteristics for Various Subway Tunnel Scenarios at 28 GHz

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Chengjian Wang ◽  
Wenli Ji ◽  
Guoxin Zheng ◽  
Asad Saleem
Keyword(s):  
Ray Tracing ◽  
Root Mean Square ◽  
Millimeter Wave ◽  
Measurement Data ◽  
Path Loss ◽  
Small Scale ◽  
Delay Spread ◽  
Mean Square ◽  
Propagation Characteristics ◽  
Subway Tunnels

In order to meet the higher data transmission rate requirements of subway communication services, the millimeter wave (mmWave) broadband communication is considered as a potential solution in 5G technology. Based on the channel measurement data in subway tunnels, this paper uses ray-tracing (RT) simulation to predict the propagation characteristics of the 28 GHz millimeter wave frequency band in different tunnel scenarios. A large number of simulations based on ray-tracing software have been carried out for tunnel models with different bending radiuses and different slopes, and we further compared the simulation results with the real time measurement data of various subway tunnels. The large-scale and small-scale propagation characteristics of the channel, such as path loss (PL), root mean square delay spread (RMS-DS), and angle spread (AS), for different tunnel scenarios are analyzed, and it was found that the tunnel with a greater slope causes larger path loss and root mean square delay spread. Furthermore, in the curved tunnel, the angle spread of the azimuth angle is larger than that in a straight tunnel. The proposed results can provide a reference for the design of future 5G communication systems in subway tunnels.

scholarly journals Electrostatic forces alter particle size distributions in atmospheric dust

2020 ◽  
Vol 20 (5) ◽  
pp. 3181-3190 ◽  
Author(s):  
Joseph R. Toth III ◽  
Siddharth Rajupet ◽  
Henry Squire ◽  
Blaire Volbers ◽  
Jùn Zhou ◽  
...  
Keyword(s):  
Electric Field ◽  
Size Distribution ◽  
Long Range ◽  
Electric Fields ◽  
Electrostatic Force ◽  
Small Scale ◽  
Size Distributions ◽  
Electrostatic Forces ◽  
Atmospheric Dust ◽  
Airborne Dust

Abstract. Large amounts of dust are lofted into the atmosphere from arid regions of the world before being transported up to thousands of kilometers. This atmospheric dust interacts with solar radiation and causes changes in the climate, with larger-sized particles having a heating effect, and smaller-sized particles having a cooling effect. Previous studies on the long-range transport of dust have found larger particles than expected, without a model to explain their transport. Here, we investigate the effect of electric fields on lofted airborne dust by blowing sand through a vertically oriented electric field, and characterizing the size distribution as a function of height. We also model this system, considering the gravitational, drag, and electrostatic forces on particles, to understand the effects of the electric field. Our results indicate that electric fields keep particles suspended at higher elevations and enrich the concentration of larger particles at higher elevations. We extend our model from the small-scale system to long-range atmospheric dust transport to develop insights into the effects of electric fields on size distributions of lofted dust in the atmosphere. We show that the presence of electric fields and the resulting electrostatic force on charged particles can help explain the transport of unexpectedly large particles and cause the size distribution to become more uniform as a function of elevation. Thus, our experimental and modeling results indicate that electrostatic forces may in some cases be relevant regarding the effect of atmospheric dust on the climate.

scholarly journals Electrostatic forces alter particle size distributions in atmospheric dust

2019 ◽  
Author(s):  
Joseph R. Toth III ◽  
Siddharth Rajupet ◽  
Henry Squire ◽  
Blaire Volbers ◽  
Jùn Zhou ◽  
...  
Keyword(s):  
Electric Field ◽  
Size Distribution ◽  
Long Range ◽  
Electric Fields ◽  
Electrostatic Force ◽  
Small Scale ◽  
Size Distributions ◽  
Electrostatic Forces ◽  
Atmospheric Dust ◽  
Airborne Dust

Abstract. Large amounts of dust are lofted into the atmosphere from arid regions of the world before being transported up to thousands of kilometers. This atmospheric dust interacts with solar radiation causing changes in the climate, with larger-sized particles having a heating effect, and smaller-sized particles having a cooling effect. Previous studies on the long-range transport of dust have found larger particles than expected, without a model to explain their transport. Here, we investigate the effect of electric fields on lofted airborne dust by blowing sand through a vertically-oriented electric field, and characterizing the size distribution as a function of height. We also model this system, considering the gravitational, drag, and electrostatic forces on particles, to understand the effects of the electric field. Our results indicate that electric fields keep particles suspended at higher elevations and enrich the concentration of larger particles at higher elevations. We extend our model from the small-scale system to long-range atmospheric dust transport to develop insights on the effects of electric fields on size distributions of lofted dust in the atmosphere. We show that the presence of electric fields and the resulting electrostatic force on particles can help explain the transport of unexpectedly larger particles and cause the size distribution to become more uniform as a function of elevation. Thus, our experimental and modelling results indicate that electrostatic forces should be considered when determining the effect of atmospheric dust on the climate.

scholarly journals Analysis of the Target Detection Performance of Air-to-Air Airborne Radar Using Long-Range Propagation Simulation in Abnormal Atmospheric Conditions

2020 ◽  
Vol 10 (18) ◽  
pp. 6440
Author(s):  
Tea Heung Lim ◽  
Minho Go ◽  
Chulhun Seo ◽  
Hosung Choo
Keyword(s):  
Long Range ◽  
Target Detection ◽  
Path Loss ◽  
Detection Performance ◽  
Airborne Radar ◽  
Atmospheric Conditions ◽  
Propagation Characteristics ◽  
Digital Terrain ◽  
Elevation Data ◽  
Terrain Elevation

In this paper, we propose the analysis of the target detection performance of air-to-air airborne radars using long-range propagation simulations with a novel quad-linear refractivity model under abnormal atmospheric conditions. The radar propagation characteristics and the target detection performance are simulated using the Advanced Refractive Effects Prediction System (AREPS) software, where the refractivity along the altitude, array antenna pattern, and digital terrain elevation data are considered as inputs to obtain the path loss of the wave propagation. The quad-linear model is used to approximate the actual refractivity data, which are compared to the data derived using the conventional trilinear refractivity model. On the basis of the propagation simulations, we propose a detection performance metric in terms of the atmosphere (DPMA) for intuitively examining the long-range propagation characteristics of airborne radars in air-to-air situations. To confirm the feasibility of using the DPMA map in various duct scenarios, we employ two actual refractive indices to observe the DPMA results in relation to the height of the airborne radar.

scholarly journals Experimental Characterization of Ultra-Wideband Channel Parameter Measurements in an Underground Mine

2011 ◽  
Vol 2011 ◽  
pp. 1-7 ◽  
Author(s):  
B. Nkakanou ◽  
G. Y. Delisle ◽  
N. Hakem
Keyword(s):  
Underground Mining ◽  
Path Loss ◽  
Measurement Procedure ◽  
Ultra Wideband ◽  
Small Scale ◽  
Scale Parameters ◽  
Channel Parameter ◽  
Channel Parameters ◽  
Uwb Channel

Experimental results for an ultra-wideband (UWB) channel parameters in an underground mining environment over a frequency range of 3 GHz to 10 GHz are reported. The measurements were taken both in LOS and NLOS cases in two different size mine galleries. In the NLOS case, results were acquired for different corridor obstruction angles. The results were obtained during an extensive measurement campaign in the UWB frequency, and the measurement procedure allows both the large- and small-scale parameters such as the path loss exponent, coherence bandwidth, and so forth, to be quantified. The capacity of the UWB channel as a function of the physical depth of the mine gallery has also been recorded for comparison purposes.

scholarly journals Ultra-small scale-free geometric networks

2006 ◽  
Vol 43 (3) ◽  
pp. 665-677 ◽  
Author(s):  
J. E. Yukich
Keyword(s):  
Long Range ◽  
Power Law ◽  
Degree Distribution ◽  
Small Scale ◽  
Graph Distance ◽  
Power Law Distribution ◽  
Scale Free

We consider a family of long-range percolation models (Gp)p>0on ℤdthat allow dependence between edges and have the following connectivity properties forp∈ (1/d, ∞): (i) the degree distribution of vertices inGphas a power-law distribution; (ii) the graph distance between pointsxandyis bounded by a multiple of logpdlogpd|x-y| with probability 1 -o(1); and (iii) an adversary can delete a relatively small number of nodes fromGp(ℤd∩ [0,n]d), resulting in two large, disconnected subgraphs.

scholarly journals Multi-Dimensional Sparse-Coded Ambient Backscatter Communication for Massive IoT Networks

Energies ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2855
Author(s):  
Tae Kim ◽  
Dong Kim
Keyword(s):  
Long Range ◽  
Orthogonal Frequency Division Multiplexing ◽  
High Rate ◽  
Huge Number ◽  
Duty Cycling ◽  
Backscatter Communication ◽  
Sufficient Energy ◽  
Backscatter Modulation ◽  
Rf Tags ◽  
Ambient Backscatter

In this paper, we propose a multi-dimensional sparse-coded ambient backscatter communication (MSC-AmBC) system for long-range and high-rate massive Internet of things (IoT) networks. We utilize the characteristics of the ambient sources employing orthogonal frequency division multiplexing (OFDM) modulation to mitigate strong direct-link interference and improve signal detection of AmBC at the reader. Also, utilization of the sparsity originated from the duty-cycling operation of batteryless RF tags is proposed to increase the dimension of signal space of backscatter signals to achieve either diversity or multiplexing gains in AmBC. We propose optimal constellation mapping and reflection coefficient projection and expansion methods to effectively construct multi-dimensional constellation for high-order backscatter modulation while guaranteeing sufficient energy harvesting opportunities at these tags. Simulation results confirm the feasibility of the long-range and high-rate AmBC in massive IoT networks where a huge number of active ambient sources and passive RF tags coexist.

Small-Scale Fading Characteristics in Cellular Networks in Ghana

2013 ◽  
Vol 5 (3) ◽  
pp. 23-33
Author(s):  
K. A. Bonsu ◽  
K. O. Boateng ◽  
J.K. Oppong ◽  
K.A. Dotche
Keyword(s):  
Communication Systems ◽  
Path Loss ◽  
Measured Data ◽  
Small Scale ◽  
Distribution Fitting ◽  
Test Technique ◽  
Received Power ◽  
Rician Distribution ◽  
Radio Signals ◽  
Correlation Properties

Fading is the most observed and frustrating problem in transmitting and receiving radio signals. A Study in correlation properties of fading helps to design proper communication systems that are robust to it. In this work, received power signal was obtained by drive-test technique. The analysis was determined using distribution fitting tool in Matlab software 7.5.0 (R2007b). The following fading distributions were used, Rayleigh, Rician, Nakagami-m, Lognormal and Weibull. Weibull fading distribution was found to give the best description of fading experienced in Ghana.On the other hand, Rician distribution, Nakagami-m distribution and lognormal distribution have less agreement with the measured data while Rayleigh fading distribution has much less agreement with measured data. The obtained mean scale parameter and the mean shape parameter in the Weibull distribution for the environment considered were 133.76 and 15.93, respectively. Furthermore, the path loss exponents in the near and far fields were also calculated; and the standard deviation of shadowing fell in the range of 4.368dB to 6.180dB.

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