scholarly journals Analysis of an Adaptive Switching Point for LTE TDD by Dynamic System-Level Simulations

2015 ◽  
Vol 61 (2) ◽  
pp. 171-178
Author(s):  
Christian Backfrieder ◽  
Gerald Ostermayer
Keyword(s):  
Dynamic System ◽  
Time Domain ◽  
Switching Point ◽  
System Level ◽  
Inhomogeneous Distribution ◽  
Static Configuration ◽  
The Time Domain ◽  
Performance Gains ◽  
Gains And Losses ◽  
System Level Simulations

Abstract This paper introduces an LTE system level simulator and presents investigations of scenarios with differently balanced traffic emergence between uplink and downlink as well as inhomogeneous distribution of link direction asymmetry. In the TDD mode of LTE, duplexing is implemented via sharing the time domain between uplink and downlink users. This is done by different switching configurations, which offer varying capacity distributions between downlink and uplink, from a downlink-heavy configuration with 90 percent of the capacity in downlink direction to uplink heavy configurations with 60 percent uplink. We utilize the available capacity perfectly by adjusting the link configuration appropriately to traffic emergence. Performance gains when selecting a configuration appropriate to the arising traffic compared to usage of a static configuration with equally distributed capacity are investigated. In case of different configurations, additional interference can occur in neighbored cells due to distinct communication direction at the same time. We clarify the differences between these scenarios and quantify the gains and losses when the switching point between uplink and downlink is variable.

On the Dynamics of Large Systems With Localized Nonlinearities

1988 ◽  
Vol 55 (4) ◽  
pp. 946-951 ◽  
Author(s):  
P. Hagedorn ◽  
W. Schramm
Keyword(s):  
Integral Equation ◽  
Dynamical Systems ◽  
Nonlinear Systems ◽  
Dynamic System ◽  
Frequency Response ◽  
Time Domain ◽  
Numerical Procedure ◽  
Linear Subsystem ◽  
Large Systems ◽  
The Time Domain

In this paper, a certain class of dynamical systems is discussed, which can be decomposed into a large linear subsystem and one or more nonlinear subsystems. For this class of nonlinear systems the dynamic behavior is represented in the time domain by means of an integral equation. A simple numerical procedure for the solution of this integral equation is given. It is also shown how the decomposition of the system can be used in measuring the frequency response of the large linear subsystem, without actually separating it from the nonlinear subsystems. An elastostatic analogy is used to illustrate the ideas and a numerical example is given for a dynamic system.

A SPICE model of an antenna for transmitting

2014 ◽  
Vol 7 (2) ◽  
pp. 173-178 ◽  
Author(s):  
Xiang Gao ◽  
Zhengwei Du
Keyword(s):  
Time Domain ◽  
Electromagnetic Compatibility ◽  
Complete System ◽  
Direct Calculation ◽  
System Level ◽  
Spice Model ◽  
Radiation Fields ◽  
Level Model ◽  
System Level Model ◽  
The Time Domain

A SPICE model of an antenna for transmitting is proposed. This model allows for the calculation of the frequency-domain radiation fields for a range of frequencies in which the model is valid, it also allows for the direct calculation of the time-domain (TD) radiation fields for an arbitrary TD excitation signal, the spectrum of which should be within the modeling range. The model is then verified by two examples, both of them demonstrate its validity. This model can be a part of a complete system-level model for electromagnetic compatibility simulation.

scholarly journals The Choice of Evaluation Vibration Car Security

2019 ◽  
pp. 1-14
Author(s):  
L. F. Zheglov ◽  
A. B. Fominykh
Keyword(s):  
Dynamic System ◽  
Frequency Domain ◽  
Time Domain ◽  
Vibration Isolation ◽  
Frequency Characteristics ◽  
Road Surface ◽  
Statistical Linearization ◽  
Support Surface ◽  
Dirt Road ◽  
The Time Domain

In the presented material of the article the debatable question - a question of a choice of the field of mathematical modeling of system of vibration isolation of the car is considered. It is known that such a problem can be solved in the frequency and time domain. Since the primary vibration isolation system of the car has non-linear elements, the question arises: how does the solution of the linearized dynamic system in the frequency domain correspond to the data of calculations of the accepted indicators in the time domain? The problem is solved with a random kinematic perturbation from the road surface. Therefore, when working in the time domain, it is necessary to pre-select the method of statistical linearization from the known in practice design of automatic control systems.Four methods of statistical linearization, using which calculations were carried out in the frequency domain, are considered. For a similar dynamic system with its initial and statistically linearized nonlinear elements, calculations were carried out in the time domain. It is shown that the first method of statistical linearization is the most adaptive, according to the amplitude-frequency characteristics of the system. Such calculations were carried out for two surfaces corresponding to the cobblestone and dirt road at different speeds of the car.The analysis of the calculated amplitude-frequency characteristics was carried out for the "resonant" speed of motion, at which the greatest manifestation of the system nonlinearity takes place. When driving in this mode, the system significantly increases the probability of losing contact with the tire support surface. This violates the safety of the vehicle and the system is out of the vibration safety analysis area. Especially this phenomenon is observed when driving on a dirt road at a "resonant" speed. The final results of the calculations are separate-frequency and integral parameters. The latter do not give priority in the selection of the area of calculation, provided the safety of the vehicle.Thus, it can be concluded that the adequacy of the calculations in the frequency and time domain under really specified conditions of the vehicle on the corresponding road surface. However, testing of the problem to be solved, for example, by the eigenfrequency vector of a conservative system, is advisable to be carried out in the frequency domain.

Study on Tuning Methodologies of Passive Vibration Absorbers

2013 ◽  
Vol 589-590 ◽  
pp. 665-669
Author(s):  
Xin Yue Li ◽  
Dong Chen ◽  
Bin Lin
Keyword(s):  
Dynamic System ◽  
Time Domain ◽  
Vibration Absorbers ◽  
Optimal Parameters ◽  
The Time Domain

This paper introduces two tuning methodologies of passive vibration absorbers named equal peaks method and equal troughs method respectively. By studying on the model of dynamic system, the optimal parameters are obtained. Furthermore, the results obtained by one method are compared to another one, and vice versa. The results show that the tuning methodologies have their own advantages and should be selected according to the industrial requirement. In the end, the responses of two methods to the excited force are compared in the time domain with Matlab.

Vehicle Vibration Safety Evaluation in the Time Domain

2018 ◽  
pp. 1-15 ◽  
Author(s):  
L. F. Zheglov ◽  
A. B. Fominykh
Keyword(s):  
Dynamic System ◽  
Frequency Domain ◽  
Time Domain ◽  
Vibration Isolation ◽  
Natural Frequencies ◽  
Spectral Characteristics ◽  
Isolation System ◽  
Vibration Isolation System ◽  
Calculation Results ◽  
The Time Domain

The article is a sequel to studies of the nonlinear vibration isolation systems of a vehicle. The first published papers considered an application of the known methods of statistical linearization when determining the vibration safety performance in the frequency domain. The frequency domain is the most adaptive in the context of analysis of the obtained calculation results and evaluation of the initial dynamic system features. Therefore, a problem to determine the adequacy range of such calculations in the frequency and time domain is relevant.The paper deals with the problem of creating a technique to determine and analyze the spectral characteristics of the vehicle vibration isolation system when modeling in the time domain. Considers as an object, a nonlinear dynamic system equivalent to the nonlinear vibration isolation system of a vehicle under its spatial vibrations. In formulating a system of equations-of-motion of the adopted system a module-based method was used. As an example, the power unit is given. Modeling of input random perturbations, provided that the solutions obtained are adequate, is based on the recurrent difference equations. The subsequent transformation of the calculation results into the frequency domain is based on the finite Fourier transforms.To determine the final parameters which characterise the effectiveness of the vibration isolation system, at the first stage of calculations the dynamic system was tested in a linear setting.The vector of natural frequencies of a conservative system defined in the frequency domain was compared with the spectrum of natural frequencies (the frequency response) calculated in the time domain. Besides, the article has carried out a conformity evaluation of the amplitude-frequency characteristics obtained in the frequency and time domain and their determining accuracy. The obtained positive results made it possible to compare and analyze the spectral characteristics of vibration signals and dynamic system in its nonlinear and linearized formulation. The coherence function, the amplitude-frequency characteristic, the spectral density of perturbation and output vibration signal, the vehicle suspension and tyre load characteristics are considered as the analyzed ones. The article compares the output characteristics of the dynamic system under consideration for the case in linear, linearized, and nonlinear formulation of the problem.

scholarly journals Visual P2–N2 Complex and Arousal at the Time of Encoding Predict the Time Domain Characteristics of Amnesia for Multiple Intravenous Anesthetic Drugs in Humans

2010 ◽  
Vol 113 (2) ◽  
pp. 313-326 ◽  
Author(s):  
Kane O. Pryor ◽  
Ruth A. Reinsel ◽  
Meghana Mehta ◽  
Yuelin Li ◽  
John T. Wixted ◽  
...  
Keyword(s):  
Power Function ◽  
Time Domain ◽  
Memory Function ◽  
Recognition Task ◽  
System Level ◽  
Negative Power ◽  
Intravenous Anesthetic ◽  
Subsequent Decay ◽  
Anesthetic Drugs ◽  
The Time Domain

Background Intravenous anesthetics have marked effects on memory function, even at subclinical concentrations. Fundamental questions remain in characterizing anesthetic amnesia and identifying affected system-level processes. The authors applied a mathematical model to evaluate time-domain components of anesthetic amnesia in human subjects. Methods Sixty-one volunteers were randomized to receive propofol (n = 12), thiopental (n = 13), midazolam (n = 12), dexmedetomidine (n = 12), or placebo (n = 12). With drug present, subjects encoded pictures into memory using a 375-item continuous recognition task, with subsequent recognition later probed with drug absent. Memory function was sampled at up to 163 time points and modeled over the time domain using a two-parameter, first-order negative power function. The parietal event-related P2-N2 complex was derived from electroencephalography, and arousal was repeatedly sampled. Each drug was evaluated at two concentrations. Results The negative power function consistently described the course of amnesia (mean R = 0.854), but there were marked differences between drugs in the modulation of individual components (P < 0.0001). Initial memory strength was a function of arousal (P = 0.005), whereas subsequent decay was related to the reaction time (P < 0.0001) and the P2-N2 complex (P = 0.007/0.002 for discrete components). Conclusions In humans, the amnesia caused by multiple intravenous anesthetic drugs is characterized by arousal-related effects on initial trace strength, and a subsequent decay predicted by attenuation of the P2-N2 complex at encoding. The authors propose that the failure of normal memory consolidation follows drug-induced disruption of interregional synchrony critical for neuronal plasticity and discuss their findings in the framework of memory systems theory.

Apodisation in the time domain

1992 ◽  
Vol 2 (4) ◽  
pp. 615-620
Author(s):  
G. W. Series
Keyword(s):  
Time Domain ◽  
The Time Domain
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