• Title/Summary/Keyword: satellite network

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Performance Analysis of Target Adapted RED Algorithm on TCP/IP based GEO Satellite Communication Network (TCP/IP 기반의 정지 위성 궤도 통신망에서 TARED 알고리즘 성능 분석)

  • 서진원;김덕년
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.29 no.6A
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    • pp.667-667
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    • 2004
  • We must design the buffer algorithm that protects traffic congestion and decreasing throughput at satellite communication network. It is important that buffer algorithm is satisfied with the good performance of transmission packet, responsibility of many connecting traffic and the QOS for connecting character. Old buffer algorithms are not the suitable algorithms when we have the satellite communication network environment. RED buffer algorithm is proposed by Floyd. It has a better performance than old buffer algorithm. But this algorithm is not well adapted a number of connecting TCP packet and changing network, so this algorithm has a bad performance on satellite communication network that is many of connecting user at same time. This paper propose the TARED(Target Adaptive RED). It has a good performance, adaptation and stability on satellite communication network and has not overflow and underflow of the buffer level.

Development of the Test and Mnitor System for Satellite Communications Payload and Network

  • Kong, Nam-Soo
    • 제어로봇시스템학회:학술대회논문집
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    • 1994.10a
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    • pp.34-37
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    • 1994
  • A satellite communications monitoring and control system(SCMCS) has been developed at ETRI to provide the capabilities of in-orbit test (IOT) for communications payload and communications system monitoring(CSM) for the satellite communications services. The paper discusses the system level design of SCMCS and its tasks.

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CPSN (complex Pi-sigma network) equalizer for the compensation of nonlinearities in satellite communication channels (위성 통신 채널의 비선형성 보상을 위한 CPSN (Complex Pi-sigma Network) 신경회로망 등화기)

  • 진근식;윤병문;신요안
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.22 no.6
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    • pp.1231-1243
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    • 1997
  • Digital satellite communication channels have nonlinearities with memory due to saturation characteristics of traveling wave tube amplifier in the satellite and transmitter/receiver linear filters. In this paper, we propose a network structure and a learning algorithm for complex pi-sigma network (CPSK) and exploit CPSN in the problem of equalization of nonlinear satellite channels. The proposed CPSN is a complex-valued extension of real-valued pi-sigma network that is a higher-order feedforward network with fast learning while greatly reducing network complexity by utilizing efficient form of polynomials for many input variables. The performance of the proposed CPSN is demonstrated by computer simulations on the equalization of complex-valued QPSK input symbols distorted by a nonlinear channel modeled as a Volterra series and additive noise. The results indicate that the CPSN shows good equalization performance, fast convergence, and less computations as compared to conventional higher-order models such as Volterra filters.

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INTRODUCTION OF DATELLITE COMMUNICATION SYSTEM TEST LANGUNGE

  • Ahn, Dong-Hyun;Jung, Won-Chan
    • 제어로봇시스템학회:학술대회논문집
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    • 1994.10a
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    • pp.229-231
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    • 1994
  • For the effective use of satellite communication transponder, tests for the payload system such as IOT(In-Orbit Test), RPM(Routine Payload Monitoring), CSM(Communicatios System Monitoring), and REV(Remote Earth-Station Verification) have to be conducted. Those tests are used in order to verify the condition and generic design of the satellite, to provide a database for operational calculations, and to maintain the quality of communication services. As the satellite communication system gets with wider expansion with higher complexity of operation, tests for the communication system also need more complex operation that usesophisticated computer-controlled measuring system. For and C language based measurement functions, which uses GPIB protocol and SCPI commands. But SICL requires knowledge of BASIC and C language as well as GPIB and SCPL system. This paper introduces a new language called CALSTEP-Control and Access Language for the Systems of Test Equipment and Payload. This language is designed for the operator to perform the tests for the satellite communication system without any special knowledge that is mentioned above. This language has very limited number of commands which are to be used to control the payload system and test equipments to perform IOT and CSM, and those commands are very readable and easy to understand, so an operator without any knowledge of BASIC and C programming language, or SICL and SCPI command can use it.

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Cooperative Transmission Scheme for Mobile Satellite Broadcasting Systems (이동 위성 방송 시스템을 위한 협력적 전송 기법 연구)

  • Ahn, Do-Seob;Park, Dong-Chul
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.20 no.9
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    • pp.890-899
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    • 2009
  • One of major services for the next generation mobile satellite system will be multimedia broadcasting and multi-casting service(MBMS). An integrated satellite and terrestrial network can be considered to provide those services seamlessly and cooperatively. This paper presents efficient cooperative transmission architectures for integrated satellite and terrestrial network. First, an integrated satellite and terrestrial system architectures is introduced, and several cooperative transmission architectures for the integrated system are derived. Extensive performance simulation results reveal that the proposed architectures can improve the system performance and make an efficient transmission.

Estimation and Prediction-Based Connection Admission Control in Broadband Satellite Systems

  • Jang, Yeong-Min
    • ETRI Journal
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    • v.22 no.4
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    • pp.40-50
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    • 2000
  • We apply a "sliding-window" Maximum Likelihood(ML) estimator to estimate traffic parameters On-Off source and develop a method for estimating stochastic predicted individual cell arrival rates. Based on these results, we propose a simple Connection Admission Control(CAC)scheme for delay sensitive services in broadband onboard packet switching satellite systems. The algorithms are motivated by the limited onboard satellite buffer, the large propagation delay, and low computational capabilities inherent in satellite communication systems. We develop an algorithm using the predicted individual cell loss ratio instead of using steady state cell loss ratios. We demonstrate the CAC benefits of this approach over using steady state cell loss ratios as well as predicted total cell loss ratios. We also derive the predictive saturation probability and the predictive cell loss ratio and use them to control the total number of connections. Predictive congestion control mechanisms allow a satellite network to operate in the optimum region of low delay and high throughput. This is different from the traditional reactive congestion control mechanism that allows the network to recover from the congested state. Numerical and simulation results obtained suggest that the proposed predictive scheme is a promising approach for real time CAC.

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An Implementation of the Real Time Transport Protocol for Satellite Internet Access Networks (위성 인터넷 액세스망 적용을 위한 실시간 전달 프로토콜의 구현 및 성능분석)

  • 이계상;진광자;안재영;오덕길
    • Proceedings of the IEEK Conference
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    • 2000.11a
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    • pp.13-16
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    • 2000
  • Recently, with the advent of satellite communication technologies, the network access service through satellites has emerged as an alternative to existing ones. Of satellite access services including multimedia services, the high speed internet access service will be one of the important services. Particularly, the efficient transportation of real time internet traffic seems very essential. The aim of this research is to examine the applicability of the IETF RTP protocol in the satellite access network. The RTP has been developed for the QoS-met transportation protocol of real time traffic over the existing best-effort internet. This paper summarizes the RTP protocol, and describes the architecture of the implementation of the RTP. And also, the compressed RTP header protocol is discussed for the applicability to the satellite link.

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QPSK Modem Design of Satellite Air-defence Warning System (위성 전군방공경보체계 QPSK 모뎀 설계)

  • Kim, Younghun
    • Journal of the Korea Institute of Military Science and Technology
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    • v.18 no.6
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    • pp.755-761
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    • 2015
  • Satellite Air-defence Warning System receives the aircraft/ballistic track information and air defense control command obtained from Master Control & Reporting Center (MCRC) and Air Missile Defence Cell (AMD Cell) Systems. It consists of terminal and control system to propagate track information and air defense control command control via the military satellite communications. In this paper, there were described track information, air defense control command, the frame structure of modem to transmit a voice information and modulation/demodulator design, network synchronization methods via the satellite network.

A Study on the Marathon Program Production using LTE Network (LTE망을 이용한 마라톤 생방송 프로그램 제작에 관한 연구)

  • Cho, Yong-Suck;Moon, Myung-Sok;Choi, Seong-Jhin
    • Journal of Satellite, Information and Communications
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    • v.12 no.2
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    • pp.15-20
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    • 2017
  • A conventional TV relay broadcast is a method of transmitting a program by means of a microwave, a leased wire, or a satellite. With the latest advances in LTE network, a relay approach using LTE mobile communications network has become increasingly competing with the traditional TV relay broadcast method. Since 2012, TV Chosun has been using the LTE network for marathon production, and channel A has also broadcast a marathon production broadcast using the LTE network. Therefore in this paper, we investigated the marathon relay method using LTE mobile communications network and compared with the traditional TV marathon relay method, and then suggested the optimum method for the marathon relay.

Bias Correction of Satellite-Based Precipitation Using Convolutional Neural Network

  • Le, Xuan-Hien;Lee, Gi Ha
    • Proceedings of the Korea Water Resources Association Conference
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    • 2020.06a
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    • pp.120-120
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    • 2020
  • Spatial precipitation data is one of the essential components in modeling hydrological problems. The estimation of these data has achieved significant achievements own to the recent advances in remote sensing technology. However, there are still gaps between the satellite-derived rainfall data and observed data due to the significant dependence of rainfall on spatial and temporal characteristics. An effective approach based on the Convolutional Neural Network (CNN) model to correct the satellite-derived rainfall data is proposed in this study. The Mekong River basin, one of the largest river system in the world, was selected as a case study. The two gridded precipitation data sets with a spatial resolution of 0.25 degrees used in the CNN model are APHRODITE (Asian Precipitation - Highly-Resolved Observational Data Integration Towards Evaluation) and PERSIANN-CDR (Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks). In particular, PERSIANN-CDR data is exploited as satellite-based precipitation data and APHRODITE data is considered as observed rainfall data. In addition to developing a CNN model to correct the satellite-based rain data, another statistical method based on standard deviations for precipitation bias correction was also mentioned in this study. Estimated results indicate that the CNN model illustrates better performance both in spatial and temporal correlation when compared to the standard deviation method. The finding of this study indicated that the CNN model could produce reliable estimates for the gridded precipitation bias correction problem.

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