scholarly journals ANALYTICAL MODEL OF PACKET TRANSMISSION OF SPEECH AND DATA IN HF RADIO CHANNELS IN A COMPLEX SIGNAL-INTERFERENCE ENVIRONMENT

2021 ◽  
Vol 1 (67) ◽  
pp. 45-49
Author(s):  
N. Markelov
Keyword(s):  
Mathematical Models ◽  
Analytical Model ◽  
Packet Transmission ◽  
Signal Interference ◽  
Complex Signal ◽  
Radio Channels ◽  
Analytical Simulation ◽  
Hf Channel

The author has carried out an analytical simulation of the process of signal formation and processing in the HF channel during packet transmission of speech and data in a complex signal-interference environment. The totality of the result obtained can be the basis for the development of complex mathematical models of HF channels.

scholarly journals Analytical Models Synthesis of Power Electronic Converters

2017 ◽  
Vol 2 (1) ◽  
Author(s):  
Achour Ales ◽  
Jean-Luc Schanen ◽  
Djelloul Moussaoui ◽  
James Roudet
Keyword(s):  
Mathematical Models ◽  
Analytical Model ◽  
Analytical Models ◽  
Electrical Network ◽  
Equivalent Circuits ◽  
Experimental Measurements ◽  
Power Electronic ◽  
Power Electronic Converters ◽  
Noise Sources ◽  
Harmonic Noise

In this paper we proposes a synthesis of different mathematical models of power electronic converters based on Thevenin/Norton equivalent circuits. Those models, composed by impedances and harmonic noise sources, are helpful to predict the conducted ElectroMagnetic Interferences (EMI) generated by converters connected to the electrical network. Moreover, the extracted impedances are determining for sizing EMC filters. The proposed analytical model is tested with PSpice simulations and validated by experimental measurements, from DC frequency until 30MHz.

scholarly journals MODIFIED PASSIVE AVAILABLE BANDWIDTH ESTIMATION IN IEEE 802.11 WLAN

2020 ◽  
Vol 19 (Number 4) ◽  
pp. 483-511
Author(s):  
Yoanes Bandung ◽  
Joshua Tanuraharja
Keyword(s):  
Mathematical Model ◽  
Mathematical Models ◽  
Ieee 802.11 ◽  
Packet Transmission ◽  
Collision Probability ◽  
Bandwidth Estimation ◽  
Available Bandwidth ◽  
Packet Collision ◽  
Available Bandwidth Estimation ◽  
Successful Packet

Quality of Service provisioning for real-time multimedia applications is largely determined by a network’s available bandwidth. Until now, there is no standard method for estimating bandwidth on wireless networks. Therefore, in this study, a mathematical model called Modified Passive Available Bandwidth Estimation (MPABE) was developed to estimate the available bandwidth passively on a Distributed Coordination Function (DCF) wireless network on the IEEE 802.11 protocol. The mathematical model developed was a modification of three existing mathematical models, namely Available Bandwidth Estimation (ABE), Cognitive Passive Estimation of Available Bandwidth V2 (cPEAB-V2), and Passive Available Bandwidth Estimation (PABE). The proposed mathematical model gave emphasis on what will be faced to estimate available bandwidth and will help in building strategies to estimate available bandwidth on IEEE 802.11. The developed mathematical model consisted of idle period synchronisation between sender and receiver, the overhead probability occurring in the Medium Access Control (MAC) layer, as well as the successful packet transmission probability. Successful packet transmission was influenced by three variables, namely the packet collision probability caused by a number of neighbouring nodes, the packet collision probability caused by traffic from hidden nodes, and the packet error probability. The proposed mathematical model was tested by comparing it with other relevant mathematical models. The performance of the four mathematical models was compared with the actual bandwidth. Using a series of experiments that have been performed, it was found that the proposed mathematical model is approximately 26% more accurate than ABE, 36% more accurate than cPEABV2, and 32% more accurate than PABE.

INVESTIGATION OF THE NON-STATIONARY TEMPERATURE FIELD IN A RESERVOIR WITH A HYDRAULIC FRACTURING BASED ON AN ANALYTICAL MODEL

2021 ◽  
Vol 7 (3) ◽  
pp. 8-24
Author(s):  
Filyus F. DAVLETSHIN ◽  
Ramil F. SHARAFUTDINOV
Keyword(s):  
Temperature Field ◽  
Hydraulic Fracturing ◽  
Mathematical Models ◽  
Analytical Model ◽  
Temperature Fields ◽  
Ansys Fluent ◽  
Flowing Liquid ◽  
Fracture Width ◽  
Fracture Parameters ◽  
Capacitive Properties

Currently, well temperature studies are widely used to solve various problems of control and monitoring of hydraulic fracturing. Temperature data measured in production wells during and after hydraulic fracturing provide important information about non-stationary filtration and thermal processes that are sensitive to fracture parameters — position and orientation, geometry and filtration characteristics. Mathematical models developed for calculating non-stationary pressure and temperature fields with known geometry and filtration-capacitive properties of the fracture and reservoir, in the general case, can be numerical and analytical. In the quantitative interpretation of temperature measurements and solving inverse problems for estimating fracture parameters, the speed of calculating the temperature field is important, in this regard, the development of analytical mathematical models of non-isothermal filtration in a reservior with a hydraulic fracturing is relevant. The paper presents the results of a study of a non-stationary formation temperature field in a reservoir with a hydraulic fracture based on an analytical model. The developed analytical model takes into account convective heat transfer, heat and mass transfer between the fracture and the formation, thermodynamic (adiabatic and Joule — Thomson) effects. To control the calculation correctness and adequacy of the temperature field, the analytical solution was compared with numerical calculations in the Ansys Fluent software package. The non-stationary temperature formation features of the fluid flowing into the well in the constant withdrawal mode at various parameters of the fracture (width and permeability) are investigated. It was found that the temperature of the fluid flowing into the well increases in inverse proportion to the width and permeability of the fracture, and in the first hour after putting the well into operation, negative dynamics of the flowing liquid temperature is observed, the duration of which increases with the growth of the fracture width.

CURRENT STATUS AND DEVELOPMENT TRENDS OF RADAR SYSTEMS AIRBORNE BASED WITH TIME-VARYING RELATIVE SPATIAL CONFIGURATION

2019 ◽  
pp. 6-14
Author(s):  
V. Druzhynin ◽  
N. Tsopa ◽  
H. Zhyrov ◽  
I. Chetverikov
Keyword(s):  
Radio Emission ◽  
Spatial Configuration ◽  
Current Status ◽  
Signal Interference ◽  
Complex Signal ◽  
Emission Sources ◽  
Time Varying ◽  
Development Trends ◽  
Radar Images ◽  
Radar Systems

The work is devoted to the review of the current state and development trends of airborne-based radar systems with a time-varying relative spatial configuration. The relevance of consideration of the state and tendencies of development of radar systems of aviation-ground based with time-varying relative spatial configuration due to the practical need to obtain radar images (radars) of objects in the front area of the system review, taking into account the growing requirements for promptness and accuracy of image detection of real-time surveillance in a complex signal-interference environment. The generalized structure of the construction of the systems considered in the work is presented and the main prospects for their practical application in solving the problems of classifying radar objects and monitoring radio emission sources are determined. Estimates are given of the main qualitative characteristics of the images of radar objects when applied when using the systems considered and the accuracy of determining the coordinates of radio emission sources is estimated based on an approved mathematical apparatus. The priority areas of scientific research on the further development of the theory of multi-positional reception of radar information in the conditions of information uncertainty when using systems with a time-variable relative spatial configuration are determined.

HF channel modeling for real-time packet transmission

2003 ◽  
Author(s):  
Mehdi Rostami ◽  
Joao Angeja ◽  
Joao Tavares ◽  
Antonio Navarro
Keyword(s):  
Real Time ◽  
Channel Modeling ◽  
Packet Transmission ◽  
Hf Channel

scholarly journals Digital Radio Networks Centralized Elements Synchronization Model with Random Multiple Access to the CSMA/CA Type Medium

2020 ◽  
pp. 128-154
Author(s):  
Maksim Peregudov ◽  
Anatoliy Steshkovoy
Keyword(s):  
Communication Networks ◽  
Analytical Model ◽  
Multiple Access ◽  
Radio Networks ◽  
Packet Transmission ◽  
Theoretical Research ◽  
Radio Network ◽  
Radio Communication ◽  
Digital Radio ◽  
Research Results

Currently, there is a great interest in digital radio network centralized elements synchronization with random multiple access to the CSMA/CA type , the effectiveness of which determines the process of establishing a communication session. At the same time, there was no assessment effectiveness digital radio communication network centralized elements synchronization with random multiple access to the CSMA/CA type. Also, there was no assessment made the contribution of potential destructive actions by the attacker to the reduction in the effectiveness of such synchronization. This paper presents digital radio networks centralized elements synchronization analytical model with random multiple access to the CSMA/CA type medium. In this model the theoretical resulting indicator is the probability of successful delivery of a synchronization package, and a package frequency of successful delivery is used in experimental indicator evaluation . The model takes into account the potential destructive effects of the attacker in analytical expressions for known probabilistic indicators. An digital radio network  centralized elements synchronization with random multiple access to a CSMA/CA type experimental study an environment is also presented. The most common network of digital radio standard IEEE 802.11 (Wi-Fi) is considered as such network. The experimental research results differ from the theoretical research results slightly, which indicates the adequacy of the developed analytical model. It was established, firstly, that the successful delivery probability of a synchronization packet does not depend on number of subscriber terminals in digital radio communication networks, secondly, with an average duration of a data packet transmission by such terminal less than 0.85 ms, it is advisable to use non-random, and the reserved multiple access to the environment, and, thirdly, centralized synchronization is resistant to destructive influences. The model is applicable in the design of digital radio networks with random multiple access to the medium such as CSMA/CA, as well as in optimizing the operation of such networks.

scholarly journals Digital Radio Networks Centralized Elements Synchronization Model with Random Multiple Access to the CSMA/CA Type Medium

2020 ◽  
Vol 19 (1) ◽  
pp. 128-154 ◽  
Author(s):  
Maksim Peregudov ◽  
Anatoliy Steshkovoy
Keyword(s):  
Communication Networks ◽  
Analytical Model ◽  
Multiple Access ◽  
Radio Networks ◽  
Packet Transmission ◽  
Theoretical Research ◽  
Radio Network ◽  
Radio Communication ◽  
Digital Radio ◽  
Research Results

Currently, there is a great interest in digital radio network centralized elements synchronization with random multiple access to the CSMA/CA type , the effectiveness of which determines the process of establishing a communication session. At the same time, there was no assessment effectiveness digital radio communication network centralized elements synchronization with random multiple access to the CSMA/CA type. Also, there was no assessment made the contribution of potential destructive actions by the attacker to the reduction in the effectiveness of such synchronization. This paper presents digital radio networks centralized elements synchronization analytical model with random multiple access to the CSMA/CA type medium. In this model the theoretical resulting indicator is the probability of successful delivery of a synchronization package, and a package frequency of successful delivery is used in experimental indicator evaluation . The model takes into account the potential destructive effects of the attacker in analytical expressions for known probabilistic indicators. An digital radio network  centralized elements synchronization with random multiple access to a CSMA/CA type experimental study an environment is also presented. The most common network of digital radio standard IEEE 802.11 (Wi-Fi) is considered as such network. The experimental research results differ from the theoretical research results slightly, which indicates the adequacy of the developed analytical model. It was established, firstly, that the successful delivery probability of a synchronization packet does not depend on number of subscriber terminals in digital radio communication networks, secondly, with an average duration of a data packet transmission by such terminal less than 0.85 ms, it is advisable to use non-random, and the reserved multiple access to the environment, and, thirdly, centralized synchronization is resistant to destructive influences. The model is applicable in the design of digital radio networks with random multiple access to the medium such as CSMA/CA, as well as in optimizing the operation of such networks.

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