scholarly journals A Measurement Based Shadow Fading Model for Vehicle-to-Vehicle Network Simulations

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Taimoor Abbas ◽  
Katrin Sjöberg ◽  
Johan Karedal ◽  
Fredrik Tufvesson
Keyword(s):  
Ad Hoc ◽  
Channel Model ◽  
Measurement Data ◽  
System Level ◽  
Line Of Sight ◽  
Shadow Fading ◽  
Video Information ◽  
Vehicle To Vehicle ◽  
The Difference ◽  
The Impact

The vehicle-to-vehicle (V2V) propagation channel has significant implications on the design and performance of novel communication protocols for vehicularad hocnetworks (VANETs). Extensive research efforts have been made to develop V2V channel models to be implemented in advanced VANET system simulators for performance evaluation. The impact of shadowing caused by other vehicles has, however, largely been neglected in most of the models, as well as in the system simulations. In this paper we present a shadow fading model targeting system simulations based on real measurements performed in urban and highway scenarios. The measurement data is separated into three categories, line-of-sight (LOS), obstructed line-of-sight (OLOS) by vehicles, and non-line-of-sight due to buildings, with the help of video information recorded during the measurements. It is observed that vehicles obstructing the LOS induce an additional average attenuation of about 10 dB in the received signal power. An approach to incorporate the LOS/OLOS model into existing VANET simulators is also provided. Finally, system level VANET simulation results are presented, showing the difference between the LOS/OLOS model and a channel model based on Nakagami-mfading.

scholarly journals Line-of-Sight Obstruction Analysis for Vehicle-to-Vehicle Network Simulations in a Two-Lane Highway Scenario

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Taimoor Abbas ◽  
Fredrik Tufvesson
Keyword(s):  
Vehicular Ad Hoc Networks ◽  
Ad Hoc ◽  
Path Loss ◽  
Mobility Model ◽  
Line Of Sight ◽  
Shadow Fading ◽  
Lane Changing ◽  
Car Following ◽  
Car Following Model ◽  
The Impact

In vehicular ad-hoc networks (VANETs) the impact of vehicles as obstacles has largely been neglected in the past. Recent studies have reported that the vehicles that obstruct the line-of-sight (LOS) path may introduce 10–20 dB additional loss, and as a result reduce the communication range. Most of the traffic mobility models (TMMs) today do not treat other vehicles as obstacles and thus cannot model the impact of LOS obstruction in VANET simulations. In this paper the LOS obstruction caused by other vehicles is studied in a highway scenario. First a car-following model is used to characterize the motion of the vehicles driving in the same direction on a two-lane highway. Vehicles are allowed to change lanes when necessary. The position of each vehicle is updated by using the car-following rules together with the lane-changing rules for the forward motion. Based on the simulated traffic a simple TMM is proposed for VANET simulations, which is capable to identify the vehicles that are in the shadow region of other vehicles. The presented traffic mobility model together with the shadow fading path-loss model can take into account the impact of LOS obstruction on the total received power in the multiple-lane highway scenarios.

scholarly journals A Statistical Modeling Methodology for Long-Term Wind Generation and Power Ramp Simulations in New Generation Locations

Energies ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 2442 ◽  
Author(s):  
Jussi Ekström ◽  
Matti Koivisto ◽  
Ilkka Mellin ◽  
Robert Millar ◽  
Matti Lehtonen
Keyword(s):  
Power Generation ◽  
Wind Power ◽  
Statistical Modeling ◽  
Renewable Energy Sources ◽  
Measurement Data ◽  
Wind Power Generation ◽  
System Level ◽  
Wind Generation ◽  
The Impact

In future power systems, a large share of the energy will be generated with wind power plants (WPPs) and other renewable energy sources. With the increasing wind power penetration, the variability of the net generation in the system increases. Consequently, it is imperative to be able to assess and model the behavior of the WPP generation in detail. This paper presents an improved methodology for the detailed statistical modeling of wind power generation from multiple new WPPs without measurement data. A vector autoregressive based methodology, which can be applied to long-term Monte Carlo simulations of existing and new WPPs, is proposed. The proposed model improves the performance of the existing methodology and can more accurately analyze the temporal correlation structure of aggregated wind generation at the system level. This enables the model to assess the impact of new WPPs on the wind power ramp rates in a power system. To evaluate the performance of the proposed methodology, it is verified against hourly wind speed measurements from six locations in Finland and the aggregated wind power generation from Finland in 2015. Furthermore, a case study analyzing the impact of the geographical distribution of WPPs on wind power ramps is included.

scholarly journals Research on Spatial Channel Model for Vehicle-to-Vehicle Communication Channel in Roadside Scattering Environment

2017 ◽  
Vol 2017 ◽  
pp. 1-12 ◽  
Author(s):  
Xin Chen ◽  
Yong Fang ◽  
Weidong Xiang ◽  
Liang Zhou
Keyword(s):  
Communication Channel ◽  
Channel Model ◽  
Critical Distance ◽  
Traffic Density ◽  
Vehicle Speed ◽  
Angle Of Arrival ◽  
Vehicle To Vehicle ◽  
Proposed Model ◽  
Spatial Channel Model ◽  
The Impact

In this paper, an extension of spatial channel model (SCM) for vehicle-to-vehicle (V2V) communication channel in roadside scattering environment is investigated for the first time theoretically and by simulations. Subsequently, to efficiently describe the roadside scattering environment and reflect the nonstationary properties of V2V channels, the proposed SCM V2V model divides the scattering objects into three categories of clusters according to the location of effective scatterers by introducing critical distance. We derive general expressions for the most important statistical properties of V2V channels, such as channel impulse response, power spectral density, angular power density, autocorrelation function, and Doppler spread of the proposed model. The impact of vehicle speed, traffic density, and angle of departure, angle of arrival, and other statistical performances on the V2V channel model is thoroughly discussed. Numerical simulation results are presented to validate the accuracy and effectiveness of the proposed model.

scholarly journals Empirical Path Loss Channel Characterization Based on Air-to-Air Ground Reflection Channel Modeling for UAV-Enabled Wireless Communications

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Jatuporn Supramongkonset ◽  
Sarun Duangsuwan ◽  
Myo Myint Maw ◽  
Sathaporn Promwong
Keyword(s):  
Wireless Communications ◽  
Wireless Communication ◽  
Channel Model ◽  
Measurement Data ◽  
Path Loss ◽  
Channel Modeling ◽  
Channel Characterization ◽  
Distance Model ◽  
Aerial Vehicle ◽  
The Impact

The purpose of this work was to investigate the air-to-air channel model (A2A-CM) for unmanned aerial vehicle- (UAV-) enabled wireless communications. Specifically, a low-altitude small UAV needs to characterize the propagation mechanisms from ground reflection. In this paper, the empirical path loss channel characterizations of A2A ground reflection CM based on different scenarios were presented by comparing the wireless communication modules for UAVs. Two types of wireless communication modules both WiFi 2.4 GHz and LoRa 868 MHz frequency were deployed to study the path loss channel characterization between Tx-UAV and Rx-UAV. To investigate the path loss, three types of experimental channel models, such as CM1 grass floor, CM2 soil floor, and CM3 rubber floor, were considered under the ground reflection condition. The analytical A2A Two-Ray (A2AT-R) model and the modified Log-Distance model were simulated to compare the correlation with the measurement data. The measurement results in the CM3 rubber floor scenario showed the impact from the ground reflection at 1 m to 3 m Rx-UAV altitudes both 2.4 GHz and 868 MHz which was converged to the A2AT-R model and related to the modified Log-Distance model above 3 m. It clear that there is no ground reflection effect from the CM1 grass floor and CM2 soil floor. This work showed that the analytical A2AT-R model and the modified Log-Distance model can deploy to model the path loss of A2A-CM by using WiFi and LoRa wireless modules.

scholarly journals Statistical Characterization of Novel 3D Cluster-Based MIMO Vehicle-to-Vehicle Models for Urban Street Scattering Environments

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Xin Chen ◽  
Yong Fang ◽  
Yanzan Sun ◽  
Yuntian Pan ◽  
Weidong Xiang
Keyword(s):  
Channel Model ◽  
Reference Model ◽  
Three Dimensional ◽  
Measurement Data ◽  
Time Correlation ◽  
Time Correlation Function ◽  
Statistical Characterization ◽  
Urban Street ◽  
Vehicle To Vehicle ◽  
V2v Communications

We develop a novel three-dimensional (3D) cluster-based channel model for vehicle-to-vehicle (V2V) communications under the scenarios of urban street scattering environments. The proposed model combines the flexibility of geometrical channel models with the existing state-of-the-art 3D V2V models. To provide an accurate representation of specific locations and realistic V2V fading environments in a computationally manageable fashion, all clusters are divided into three groups of use cases including “ahead,” “between,” and “behind” clusters according to the relative locations of clusters. Using the proposed V2V model, we first derive the closed-form expressions of the channel impulse response (CIR), including the line-of-sight (LoS) components and cluster components. Subsequently, for three categories of clusters, the corresponding statistical properties of the reference model are studied. We additionally derive the expressions of the 3D space-time correlation function (STCF), the autocorrelation function (ACF), and 2D STCF. Finally, comparisons with on-road measurement data and numerical experiments demonstrate the validity and effectiveness of the proposed 3D cluster-based V2V model.

scholarly journals Quantifying the Impact of the Covid-19 Lockdown Measures on Nitrogen Dioxide Levels throughout Europe

Atmosphere ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 131
Author(s):  
Sverre Solberg ◽  
Sam-Erik Walker ◽  
Philipp Schneider ◽  
Cristina Guerreiro
Keyword(s):  
Nitrogen Dioxide ◽  
Temporal Trends ◽  
Measurement Data ◽  
Additive Model ◽  
Generalised Additive Model ◽  
The Difference ◽  
The One ◽  
The Impact ◽  
Good Agreement ◽  
Model Approach

In this paper, the effect of the lockdown measures on nitrogen dioxide (NO2) in Europe is analysed by a statistical model approach based on a generalised additive model (GAM). The GAM is designed to find relationships between various meteorological parameters and temporal metrics (day of week, season, etc.) on the one hand and the level of pollutants on the other. The model is first trained on measurement data from almost 2000 monitoring stations during 2015–2019 and then applied to the same stations in 2020, providing predictions of expected concentrations in the absence of a lockdown. The difference between the modelled levels and the actual measurements from 2020 is used to calculate the impact of the lockdown measures adjusted for confounding effects, such as meteorology and temporal trends. The study is focused on April 2020, the month with the strongest reductions in NO2, as well as on the gradual recovery until the end of July. Significant differences between the countries are identified, with the largest NO2 reductions in Spain, France, Italy, Great Britain and Portugal and the smallest in eastern countries (Poland and Hungary). The model is found to perform best for urban and suburban sites. A comparison between the found relative changes in urban surface NO2 data during the lockdown and the corresponding changes in tropospheric vertical NO2 column density as observed by the TROPOMI instrument on Sentinel-5P revealed good agreement despite substantial differences in the observing method.

scholarly journals Analytical Nonstationary 3D MIMO Channel Model for Vehicle-to-Vehicle Communication on Slope

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Kaizhen Liu ◽  
Zaixue Wei ◽  
Sibo Chen
Keyword(s):  
Communication Systems ◽  
Channel Model ◽  
Multiple Input Multiple Output ◽  
Measurement Data ◽  
Special Kind ◽  
Mimo Channel ◽  
Future Research ◽  
Vehicle Communication ◽  
Vehicle To Vehicle ◽  
Vehicle To Vehicle Communication

Vehicle-to-vehicle communication plays a strong role in modern wireless communication systems, appropriate channel models are of great importance in future research, and propagation environment with slope is one special kind. In this study, a novel three-dimensional nonstationary multiple-input multiple-output channel model for the sub-6 GHz band is proposed. This model is a regular-shaped multicluster geometry-based analytical model, and it combines the line-of-sight component and multicluster scattering rays as the nonline-of-sight components. Each cluster of scatterers represents the influence of different moving vehicles on or near a slope, and scatterers are, respectively, distributed within two spheres around the transmitter and the receiver. In this model, it is considered that the azimuth and elevation angles of departure and arrival are jointly distributed and conform to the von Mises–Fisher distribution, which can easily control the range and concentration of the scatterers within spheres to mimic the real-world situation well. Moreover, the impulse response and the autocorrelation function of the corresponding channel is derived and proposed; then, the Doppler power spectrum density of the channel is simulated and analyzed. In addition, the nonstationary characteristics of the presented channel model are observed through simulations. Finally, the simulation results are compared with measurement data in order to validate the utility of the proposed model.

scholarly journals The Impact of the COVID-19 Pandemic on User Experience with Online Education Platforms in China

2020 ◽  
Vol 12 (18) ◽  
pp. 7329 ◽  
Author(s):  
Tinggui Chen ◽  
Lijuan Peng ◽  
Bailu Jing ◽  
Chenyue Wu ◽  
Jianjun Yang ◽  
...  
Keyword(s):  
Online Education ◽  
User Experience ◽  
Evaluation Method ◽  
Comprehensive Evaluation ◽  
Relevant Literature ◽  
Evaluation Index System ◽  
Video Information ◽  
Before And After ◽  
The Difference ◽  
The Impact

During the COVID-19 pandemic, social education has shifted from face to face to online in order to avoid large gatherings and crowds for blocking the transmission of the virus. To analyze the impact of virus on user experience and deeply retrieve users’ requirements, this paper constructs a reasonable evaluation index system through obtaining user reviews about seven major online education platforms before and after the outbreak of COVID-19, and by combining the emotional analysis, hot mining technology, as well as relevant literature. At the same time, the variation coefficient method is chosen to weigh each index based on the difference of index values. Furthermore, this paper adopts the comprehensive evaluation method to analyze user experience before and after the outbreak of COVID-19, and finally finds out the change of users’ concerns regarding the online education platform. In terms of access speed, reliability, timely transmission technology of video information, course management, communication and interaction, and learning and technical support, this paper explores the supporting abilities and response levels of online education platforms during COVID-19, and puts forward corresponding measures to improve how these platforms function.

Effect of Driver and Work Cycle on Losses of a Loader

2018 ◽  
Author(s):  
Seppo Tikkanen ◽  
Ville Ahola ◽  
Elias Koskela
Keyword(s):  
Energy Consumption ◽  
Energy Distribution ◽  
Fuel Consumption ◽  
Measurement Data ◽  
Initial State ◽  
Design Work ◽  
Skill Levels ◽  
Work Cycle ◽  
The Difference ◽  
The Impact

Improving the energy efficiency of mobile machines requires information about the initial state of the machine. This information includes knowledge of the systems and their components and of course, measurement data that is acquired during typical operation. Machine manufacturers and research institutes have carried out extensive measurement programs during the last decade. Usually, the published studies concentrated on one work cycle, the machines studied were operated by humans, and it is shown that productivity and fuel consumption are dependent on the machine design, work cycle and operator. This study concentrates on a detailed analysis of the energy consumption of a municipal loader during measured work tasks. The goal was to find out how much the driver and work cycle affect the machine’s energy consumption and energy distribution. To evaluate the real fuel consumption and energy distribution, the measurements consisted of two different work cycles that were driven by two drivers with different skill levels. The first cycle was the classic short wheel loader loading cycle, the Y-cycle. In this task, the loader was equipped with a bucket, and a pile of gravel was moved from pile A to pile B in a Y-pattern. The second cycle was the load and carry cycle in which the driver picked up a load with the forklift attachment and carried the load over a predefined distance. The major finding was that the impact of the driver and the work cycle is considerable in fuel consumption. The difference is also seen in the energy distribution in the hydraulic system and in losses and how the losses are divided. Therefore, it can be stated that test results with one driver or one cycle should not be generalized without concern and judgement of novel concepts requires several tests with different drivers and work cycles.

scholarly journals Morphology Effect of Surface Structures on Microchannel Flow Using Lattice Boltzmann Method

Geofluids ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-14
Author(s):  
Ge Zhang ◽  
Bo Liu ◽  
Aiguo Xu ◽  
Yiming Shan ◽  
Yingjun Li
Keyword(s):  
Fluid Flow ◽  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Channel Model ◽  
Rock Surface ◽  
Microchannel Flow ◽  
Morphology Effect ◽  
The Difference ◽  
Boltzmann Method ◽  
The Impact

Microchannel flow shows a fascinating background on a lot of engineering problems. In order to shed a light on the effect of the surface morphology of microchannels on fluid flow, differently shaped and arranged artificial elements constitute channels with different morphology and numerical simulation based on lattice Boltzmann method is conducted. The impact of micro effect is also stressed by comparing the results considering and not considering it in the same channel model. Analysis of flow details shows the difference of the morphology effect on fluid flow, which differs by the shape and density of the elements’ array. The permeability of channels shows a specific relationship with the density of artificial elements, and differences are found between varied shapes and the existence of micro effects. Further research is carried based on more complex channels with arrays of fractal-character artificial elements. As elements in the channel can be divided into main summits and subsummits, their different roles of the effect on the fluid flow is investigated. The result shows that the permeability will not change if main summits are kept in channels while all subsummits are removed to make a distinct simplification of the morphology. This discovery is furtherly ensured numerically by a test on a channel created with the profile of a rough rock surface. The finding for morphology effect on fluid flow can supply a reference for the prediction of the permeability of complex channels or fractures.

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