scholarly journals Modeling and Performance Optimization of Unmanned Aerial Vehicle Channels in Urban Emergency Management

2021 ◽  
Vol 10 (7) ◽  
pp. 478
Author(s):  
Bing Han ◽  
Danyang Qin ◽  
Ping Zheng ◽  
Lin Ma ◽  
Merhawit Berhane Teklu
Keyword(s):  
Emergency Management ◽  
Bit Error Rate ◽  
Error Rate ◽  
Performance Optimization ◽  
Information Exchange ◽  
Channel Model ◽  
Single Channel ◽  
Smart Cities ◽  
Small Scale ◽  
Low Altitude

With the development of smart cities, the use of unmanned aerial vehicles (UAVs) for interactive information exchange between air and ground can provide effective support for the deployment of emergency work. However, the existing UAV air-to-ground channels often use a single channel model. Considering that the density and distribution of obstructions on information transmission paths at different heights are different, only using a single channel model greatly affects the reliability of communications. Aiming at addressing the different channel characteristics of air-to-ground channels at different heights, a height-based adaptive SUUL-SULA channel model is proposed in this paper. Firstly, in the ultra-low altitude environment, the influence of large-scale fading and small-scale fading on the envelope of the received signal is discussed based on the classic LOO model, and the probability density function and bit error rate model of the received signal are derived. Secondly, a SULA channel model based on Jakes’ model is proposed in the low-altitude environment. The uniform circular array beamforming technology is adopted to realize the design of the Doppler frequency shift compensation algorithm. Finally, the simulation results show that the SUUL-SULA model effectively reduces the bit error rate of the system and improves the reliability of communication. Therefore, this model can provide effective physical support for the application of UAV in smart city emergency management.

scholarly journals Bit Error Rate Analysis of Different Modulation Schemes in Free Space Optics Link using Gamma-Gamma Turbulence Model

2019 ◽  
Vol 8 (4) ◽  
pp. 8292-8295
Keyword(s):  
Phase Shift ◽  
Gamma Distribution ◽  
Bit Error Rate ◽  
Error Rate ◽  
Free Space ◽  
Channel Model ◽  
Distribution Model ◽  
Phase Shift Keying ◽  
Free Space Optical ◽  
Shift Keying

Free Space Optical (FSO) link using gamma-gamma channel model has been studied in this paper. Comparison of the probability density function of gamma-gamma distribution under weak and strong turbulence regime has been performed. Performance of Bit error rate (BER) using different subcarrier-intensity modulation (SIM) schemes such as binary phase shift keying (BPSK), M-ary phase shift keying (M-PSK) and quadrature amplitude modulation (QAM) have been also investigated. Using MATLAB software, the BER is plotted with respect to normalized signal to noise ratio (SNR) and the link distance. All the analysis has been done using the Gamma-Gamma distribution model. In this work we found that the effectiveness of each modulation technique depends on the environment.

Modified DP-Q and MGF BER

2015 ◽  
pp. 285-296
Keyword(s):  
Bit Error Rate ◽  
Error Rate ◽  
Single Channel ◽  
Qualitative Behavior ◽  
Differential Phase Shift ◽  
Wavelength Division ◽  
Differential Phase ◽  
Wavelength Division Multiplexed ◽  
Shift Keying ◽  
Point To Point

The optical return-to-zero differential phase shift keying system is analyzed in this chapter to determine the accuracy of the recently proposed differential phase Q method in estimating the bit error rate. It is found that this method consistently underestimates the bit error rate though it successfully predicts the qualitative behavior of single channel and wavelength division multiplexed systems for back-to-back and point-to-point configurations. A simple modification reduced the underestimation and produced highly accurate estimation.

scholarly journals A Time-Varying Filter for Doppler Compensation Applied to Underwater Acoustic OFDM

Sensors ◽  
2018 ◽  
Vol 19 (1) ◽  
pp. 105 ◽  
Author(s):  
Habib Roudsari Mirhedayati ◽  
Jean-François Bousquet
Keyword(s):  
Bit Error Rate ◽  
Error Rate ◽  
Doppler Effect ◽  
Orthogonal Frequency Division Multiplexing ◽  
Channel Model ◽  
Time Varying ◽  
Ofdm Symbol ◽  
Low Snr ◽  
Time Scaling ◽  
Doppler Compensation

This paper describes a Doppler compensation algorithm to improve the reliability of orthogonal frequency division multiplexing (OFDM). To compensate for the time-varying Doppler effect in a mobile deployment scenario, first the time-scaling factor over a wideband channel is estimated using pilot tones inserted in each OFDM symbol. Then, using a time-varying resampling technique, the Doppler effect is compensated during the reception of each OFDM symbol in the frame. To predict the performance of the system in relatively shallow waters, a software channel model is developed that is able to simulate a wide variety of dynamic shallow water deployment scenario. The performance of the algorithm was tested for two extreme frequency ranges during sea trials, the first at 2 kHz for a long-range application, and the second at 125 kHz for a short range telemetry link. For the 2-kHz system, a 16-bps mobile link in which the platform was moving at 1 m/s was demonstrated to have a bit error rate on the order of 10 − 3 , while, for the 125-kHz telemetry application, a 2000-bps link was enabled with a bit error rate of 0.03 at a low SNR equal to 5.5 dB.

Performance Analysis of 10Gbps Optical Communication System by Simulation

2013 ◽  
Vol 765-767 ◽  
pp. 2691-2695
Author(s):  
Yu Ma ◽  
Li Ying Liu ◽  
Xiao Fei Wang ◽  
Jiu Ru Yang
Keyword(s):  
Performance Analysis ◽  
Optical Communication ◽  
Bit Error Rate ◽  
Error Rate ◽  
Communication System ◽  
High Speed ◽  
Single Channel ◽  
Optical Communication System

It is difficult to study the characteristics of high speed optical communication system due to the complexity and high-cost in configuration. In this paper, aiming to overcome the weakness above, the performance of a 10Gbps optical communication system with single channel is investigated by simulation. Then, based on the outputs of RZ and NRZ codes modulated, an extensive comparison is developed in terms of spectrums, noises, eye diagrams and bit error rate.

scholarly journals Identification of the acoustic signal models of audio exchange systems under conditions of interference and acoustic feedback

2020 ◽  
Vol 44 (3) ◽  
pp. 454-465
Author(s):  
V.A. Ermolaev ◽  
Y.A. Kropotov ◽  
A.Y. Proskuryakov
Keyword(s):  
Information Exchange ◽  
Channel Model ◽  
Transfer Functions ◽  
Single Channel ◽  
Distributed Delay ◽  
Delayed Feedback ◽  
Practical Significance ◽  
Closed Space ◽  
Frequency Method ◽  
Analysis Of Stability

In this paper questions of building models of information exchange systems with discrete and distributed delay and with delayed feedback by methods of the theory of linear functional differential equations are investigated. When solving the said equations, it is necessary to consider restrictions caused by the uncertainties in the system under modeling, such as the absence of the exact data on the parameters of the model elements, their natural spread and temporal variations, thus requiring the solution of an identification problem. The models with continuous aftereffect introduced in this work take a fuller account of reflected signal characteristics in closed space, which increases the reliability of modeling results in comparison with the known differential models. At the same time, there is a problem of finding functions that characterize the value distribution of the echo delay. In this work, these functions (kernels) are approximated by a number of exponents, which simplifies the equations and allows the assumption that the aftereffect can be concentrated on both final and infinite intervals. The echo components caused by closed-space resonances are modeled by transfer functions of the corresponding linear links. In numerical modeling, a single-channel model represented by a second-order resonance link and a pulse-shaped kernel described by a sum of two decreasing exponents is considered. The analysis of stability of the models of systems with delayed feedback is conducted by a frequency method. In the paper an approach to estimating the correlation and spectral functions of signals and noise components based on the parametric representation of the latter is considered. The paper also considers issues relating to the practical significance of the research results.

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