scholarly journals Model of Satellite Communication Channel Functioning under Conditions of Disturbances of Service Part of Frames by Unsteady Interference

2020 ◽  
Vol 19 (5) ◽  
pp. 967-990
Author(s):  
Andrey Parshutkin ◽  
Dmitriy Buchinskiy
Keyword(s):  
Communication Systems ◽  
Communication Channel ◽  
Noise Immunity ◽  
Satellite Communication ◽  
Block Diagram ◽  
Satellite Communications ◽  
Frame Synchronization ◽  
Code Structure ◽  
Service Information ◽  
The Impact

The paper describes the main ways of organizing modern satellite communication systems and the methods of synchronization and transmission of service information used in them, the frame synchronization mechanism from the view point of noise immunity. Based on the analysis, a block diagram of a simulation model is proposed for studying the influence of unintentional interference on the channels of modern satellite communication systems. The proposed model of the impact of non-stationary interference on a satellite communication channel takes into account the effect of interference on symbolic, frame synchronization, mechanisms for extracting frame boundaries, as well as the effect of modern error correction codes. The model allows evaluating the impact of non-stationary interference on both the information and the service side of the frame of modern systems of broadband satellite communications. As an indicator of the noise immunity of a satellite communication channel, there was used probability of frame loss, i.e. frame skipping due to a violation in the frame synchronization system, incorrect allocation of frame boundaries, or the presence of errors in the frame that were not repaired by corrective codes. Using this model, we studied the effect of non-stationary interference of various durations on the information and service parts of the frame, compared the results of the impact of non-stationary interferences of various durations with the effect of white Gaussian noise. It is shown that non-stationary interference, which are short noise pulses that do not affect the information part of the frame due to reparation by correction codes, can significantly reduce the reception quality due to disruption of frame synchronization and distortion of service information about the signal-code structure and frame length.

INNOVATIVE METHOD OF SATELLITE COMMUNICATION

2019 ◽  
Author(s):  
Teodor Narytnik ◽  
Vladimir Saiko
Keyword(s):  
Communication Systems ◽  
High Speed ◽  
Satellite Communication ◽  
Radio Channel ◽  
Satellite Communications ◽  
Service Area ◽  
Satellite Systems ◽  
Orbit Satellite ◽  
Geometric Size ◽  
Distributed Satellite

The technical aspects of the main promising projects in the segments of medium and low-orbit satellite communication systems are considered, as well as the project of the domestic low-orbit information and telecommunications system using the terahertz range, which is based on the use of satellite platforms of the micro- and nanosatellite class and the distribution of functional blocks of complex satellite payloads more high-end on multiple functionally related satellites. The proposed system of low-orbit satellite communications represents the groupings of low-orbit spacecraft (LEO-system) with the architecture of a "distributed satellite", which include the groupings of the root (leading) satellites and satellite repeaters (slaves). Root satellites are interconnected in a ring network by high-speed links between the satellites. The geometric size of the “distributed satellite” is the area around the root satellite with a radius of about 1 km. The combination of beams, which are formed by the repeater satellites, make up the service area of the LEO system. The requirements for the integrated service area of the LEO system (geographical service area) determine the requirements for the number of distributed satellites in the system as a whole. In the proposed system to reduce mutual interference between the grouping of the root (leading) satellites and repeater satellites (slaves) and, accordingly, minimizing distortions of the information signal when implementing inter-satellite communication, this line (radio channel) was created in an unlicensed frequency (e.g., in the terahertz 140 GHz) range. In addition, it additionally allows you to minimize the size of the antennas of such a broadband channel and simplify the operation of these satellite systems.

ON-BOARD DIGITAL SWITCHING OPTIONS FOR CIVIL COMMUNICATION SATELLITES

2020 ◽  
Author(s):  
О.В. МЕНТУС ◽  
А.А. АКОПОВ
Keyword(s):  
Communication Systems ◽  
Satellite Communication ◽  
Satellite Communications ◽  
Provision Of Services ◽  
Digital Switching ◽  
Switching Options

Рассматриваются варианты построения полезных нагрузок с цифровой коммутацией для спутниковой связи на примере перспективного космического аппарата «Экспресс-АМУ4». Показано, что использование цифровой коммутации в отечественных спутниках связи позволяет обеспечить гибкость оказания услуг и более успешно конкурировать с зарубежными спутниковыми системами связи. This article considers variants of digital switching payloads for satellite communications on the example of a promising spacecraft Express-AMU4. It is shown that the use of digital switching in domestic communication satellites allows providing flexibility in the provision of services and more successfully competing with foreign satellite communication systems.

scholarly journals Model of forming a spatial-temporary radio frequency portrait of subscriber terminals in satellite communication systems monitoring

2020 ◽  
Vol 100 (4) ◽  
pp. 78-86
Author(s):  
M. Baldychev ◽  
◽  
A. Bosyy ◽  
O. Galtseva ◽  
Keyword(s):  
Radio Frequency ◽  
Software Defined Radio ◽  
Communication Systems ◽  
Satellite Communication ◽  
A Priori ◽  
Complex Structure ◽  
Satellite Communications ◽  
Physical Parameters ◽  
Time Frequency ◽  
Spatio Temporal

Currently, the development of satellite communications systems (SCS) is associated with the development of signals of complex structure. The popularization and distribution of software-defined radio systems (Software-defined radio, SDR) are noted, which leads to a decrease of quality of functioning of the SCS. Promising areas of countering the unauthorized use of the time-frequency resource of the KA repeater are methods aimed at determining the location of subscriber terminals (ST) and analyzing the service and semantic parts of the transmitted message. Accounting for changes of physical parameters requires the use of a large amount of heterogeneous a priori data; it is not achievable task in practice. According to the theory of mathematical statistics, the approximation is used at solving problems of sample analysis. The result of the approximation is a spatio-temporal radio-frequency portrait (STRFP) of an ST participating in the formation of a group signal. Thus, the aim of the research is to develop a model of changing the physical parameters of a radio signal and to study the possibility of approximating physical parameters in order to form a spatio-temporal radiofrequency portrait of an ST SCS.

Joint Selection of OFDM Parameters in Mobile Satellite Communications

2013 ◽  
Vol 385-386 ◽  
pp. 1586-1590
Author(s):  
Jia Jia Wang ◽  
Cheng Mei Li ◽  
Bin Li ◽  
Hao Chang ◽  
Jian Jun Wu
Keyword(s):  
Satellite Communication ◽  
Doppler Frequency ◽  
Satellite Communications ◽  
System Capacity ◽  
Delay Spread ◽  
Numeric Calculation ◽  
Mobile Satellite ◽  
The Impact ◽  
Mobile Satellite Communication ◽  
Selection Of

In mobile satellite communication based on OFDM technology, the system performance can’t be optimal if the cyclic prefix (CP) length and subcarrier interval of LTE specification are transplanted into mobile satellite communication directly. In this paper, we analyze the impact of inter symbol interference (ISI) and inter carrier interference (ICI) which are caused by multipath delay spread and Doppler frequency shift separately on system capacity, and derive the optimal CP length and subcarrier interval for GEO, MEO and LEO mobile satellite communication by numeric calculation. Finally, the simulation results show that the OFDM parameters of LTE specification can be used in GEO mobile satellite communications, but cannot in MEO and LEO.

Forced-Retransmission Based Hybrid HARQ Scheme for GEO Satellite Communications

2013 ◽  
Vol 846-847 ◽  
pp. 651-654
Author(s):  
Ya Dan Zheng ◽  
Jian Bo Li ◽  
Yong Luo ◽  
Ming Ke Dong ◽  
Jian Jun Wu
Keyword(s):  
Communication System ◽  
Communication Systems ◽  
Satellite Communication ◽  
Satellite Communications ◽  
Hybrid Scheme ◽  
Satellite Communication System ◽  
Geo Satellite ◽  
Simulation Results

In this paper, a hybrid HARQ scheme was proposed by combing forced retransmission and traditional HARQ together, after analyzing the characteristics of satellite channel and the problem encountered when utilizing HARQ scheme in GEO satellite communication system. The forced retransmission can make a packet be correctly decoded more quickly and shorten the waiting delay. Meanwhile, to balance the delay and throughput, the proper parameters were given for the proposed hybrid scheme. Simulation results show that the proposed scheme performs well at decreasing the waiting delay, especially when SNR is low. The conclusion can be drawn that the proposed scheme can improve the HARQ performance in GEO satellite communication systems.

scholarly journals INNOVATIVE SOLUTION FOR LEO-SYSTEM WITH DISTRIBUTED SATELLITE ARCHITECTURE

2020 ◽  
pp. 77-83
Author(s):  
Volodymyr Saiko ◽  
Teodor Narytnyk ◽  
Valeriy Gladkykh ◽  
Natalia Sivkova
Keyword(s):  
Communication Systems ◽  
High Speed ◽  
Satellite Communication ◽  
Fog Computing ◽  
Satellite Communications ◽  
Access Time ◽  
Artificial Satellites ◽  
Practical Implementation ◽  
Innovative Solution ◽  
Distributed Satellite

An innovative solution for practical implementation in a LEO system with a "distributed satellite" architecture that can be used to provide low-orbital spacecraft communications with ground stations and users of 5G / IoT satellite services is proposed. The essence of the proposed development in the system of low-orbital satellite communication with FC-architecture is that to reduce the delay in signaling to consumers and the probability of overloading the network into a prospective system of low-orbital satellite communication, which contains artificial Earth satellites, each of which functions in Earth orbit and equipped with onboard repeaters, inter-satellite communications, a network of ground-based communication and control systems for artificial satellites of the Earth, a grouping of low-orbiting space their devices (LEO-system), which includes the grouping of root (leading) satellites and satellites-repeaters (slave), around each root satellite is formed micro-grouping of satellites-repeaters, and functions of the root satellite in the selected orbital phase of the orbital -or micro-satellites that are connected to the annular network by communication lines between satellites, and - functions of satellites-repeaters - kubsat, new is the introduction of a multilevel boundary cloud system, which is a heterogeneity distributed computing cloud structure. At the same time, the boundary clouds of the multilevel system are connected by ultra-high-speed wireless terahertz radio lines and wireless optical communication systems. The technique of estimation of access time in the proposed structure of "fog computing" on the basis of the model of access in "fog computing" with the resolution of collisions of data sources implementing the survey mode is presented.

scholarly journals Study of the corrective ability of sync codes for the matched processing decoder

2018 ◽  
pp. 17-23
Author(s):  
A. V. Sadchenko ◽  
O. A. Kushnirenko ◽  
A. G. Yurkevych ◽  
V. S. Sevastianov
Keyword(s):  
Communication Systems ◽  
Information Transfer ◽  
Noise Immunity ◽  
Side Lobe ◽  
Binary Sequences ◽  
Main Peak ◽  
Side Lobe Level ◽  
Frame Synchronization ◽  
Minimax Criterion ◽  
Periodic Autocorrelation Function

Increase of the operation reliability of the frame synchronization schemes of communication systems affected by interferences might be achieved by using sync sequences optimal according to the minimax criterion and having the best ratio of the maximum side-lobe level to the main peak of the non-periodic autocorrelation function. Obviously, the longer the minimax sequence, the higher its correction ability. However, with the increase in the length of the sync code, a conflict arises between the corrective ability and the speed of data transfer. This is caused by the decrease in the duration of the information section of the frame. At the same time, as the length of the code increases, the complexity of the technical implementation of the decoder synchronization scheme increases as well. This means that when developing an information transmission system, it is necessary to find a compromise between the complexity of the technical implementation of the decoder and the required noise immunity. To solve this problem, it is necessary to study the correcting ability of binary sync codes. The purpose of this work was to study the correcting ability of binary sequences with good non-periodic auto-correlation properties using a reception scheme with matched processing. This article discusses the possibility of using Barker sequences of lengths 7, 11, and 13 and M-sequences as corrective sync codes. The authors carry out an analysis of the correcting ability of the decoder model with matched processing for Barker codes of different lengths under the conditions of a one, two, and threefold error. Analytical expressions have been obtained to determine the decoding error probability of a binary minimax code depending on the length of the sync code. The dependence of the corrective ability of the code and the maximum level of the side lobe on the length of the sync code in the range from 4 to 128 with the best nonperiodic autocorrelation functions (NPAF) is obtained. It has been established that there are length ranges for minimax sequences within which their correction ability remains constant, that is, a sync code of shorter length has the same correction ability as a longer code. Thus, the research results allow us to optimize the complexity of the technical implementation of a sync signal decoder depending on the requirements for general noise immunity and information transfer rate in a communication system. The proposed approach can be successfully used to modify the existing synchronization schemes of communication systems with code division of channels.

scholarly journals A Hybrid Beamforming Design for Massive MIMO LEO Satellite Communications

2021 ◽  
Vol 2 ◽  
Author(s):  
Joan Palacios ◽  
Nuria González-Prelcic ◽  
Carlos Mosquera ◽  
Takayuki Shimizu ◽  
Chang-Heng Wang
Keyword(s):  
Communication Systems ◽  
Satellite Communication ◽  
Channel Model ◽  
Satellite Communications ◽  
Mobile Terminal ◽  
Low Earth Orbit ◽  
Special Focus ◽  
Codebook Design ◽  
Hybrid Beamforming ◽  
Leo Satellite

5G and future cellular networks intend to incorporate low earth orbit (LEO) satellite communication systems (SatCom) to solve the coverage and availability problems that cannot be addressed by satellite-based or ground-based infrastructure alone. This integration of terrestrial and non terrestrial networks poses many technical challenges which need to be identified and addressed. To this aim, we design and simulate the downlink of a LEO SatCom compatible with 5G NR, with a special focus on the design of the beamforming codebook at the satellite side. The performance of this approach is evaluated for the link between a LEO satellite and a mobile terminal in the Ku band, assuming a realistic channel model and commercial antenna array designs, both at the satellite and the terminal. Simulation results provide insights on open research challenges related to analog codebook design and hybrid beamforming strategies, requirements of the antenna terminals to provide a given SNR, or required beam reconfiguration capabilities among others.

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