• Title/Summary/Keyword: Satellite Link Simulator

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The link performance analysis of the satellite communications system using satellite network simulator (모의위성망을 활용한 위성통신체계의 링크성능 분석)

  • Jang, Jae-Woong
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.32 no.5A
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    • pp.441-450
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    • 2007
  • In this paper, it is proposed the link performance analysis results using SNRAT(Satellite Network Resource Allocation & Analysis Tool) and verified the anticipated results by satellite communication network simulator. A communication satellite cannot be corrected or fixed for the error in orbit operation after launching unlike the ground operation equipment and has a restricted operation life. So, it is important to make possible to use satellite communications in the proper time. It is expected the link BER(Bit Error Rate), throughput and AJ(Anti-Jamming) performance using SNRAT tool before launching. And it is verified the performance of the repeaters and ground equipment specification using the satellite network simulator and is extracted the optimum operational scenarios through the tests of various network operational plans.

Satellite Link Simulator Development in 100 MHz Bandwidth to Simulate Satellite Communication Environment in the Geostationary Orbit (정지궤도 위성통신 환경모의를 위한 100 MHz 대역폭의 위성링크 시뮬레이터 개발)

  • Lee, Sung-Jae;Kim, Yong-Sun;Han, Tae-Kyun
    • Journal of the Korea Institute of Military Science and Technology
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    • v.14 no.5
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    • pp.842-849
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    • 2011
  • The transponder simulator designed to simulate the transponder of military satellite communication systems in the geostationary orbit is required to have time delay function, because of 250 ms delay time, when a radio wave transmits the distance of 36,000 km in free space. But, it is very difficult to develop 250 ms time delay device in the transponder simulator of 100 MHz bandwidth, due to unstable operation of FPGA, loss of memory data for the high speed rate signal processing. Up to date, bandwidth of the time delay device is limited to 45 MHz bandwidth. To solve this problem, we propose the new time delay techniques up to 100 MHz bandwidth without data loss. Proposed techniques are the low speed down scaling and high speed up scaling methods to read and write the external memory, and the matrix structure design of FPGA memory to treat data as high speed rate. We developed the satellite link simulator in 100 MHz bandwidth using the proposed new time delay techniques, implemented to the transponder simulator and verified the function of 265 ms time delay device in 100 MHz bandwidth.

A simulator for delay-time and bit error generation on geostationary satellite communication link (정지궤도 위성채널 지연과 비트에러 발생 시뮬레이터)

  • Park, Gyeong-Yeol
    • Journal of Satellite, Information and Communications
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    • v.1 no.1
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    • pp.20-25
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    • 2006
  • The link of Geostationary Communication Satellite has transit delay and noise environments by physical distance. This situation exerts an influence on the degradation of baseband performance of Earth Station. Therefore, it is very important that degradation of baseband performance is grasped previously. This paper is presented that developed the simulator which can evaluate the baseband performance of earth station of a military satellite communication system during the current development. The simulator can mock delay on a satellite channel and bit errors without being used actual satellite links.

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A Study on the CDMA-based TT&C Design and Experiment Concept

  • Lee, Ho-Jin;Mo, Hee-Sook
    • 제어로봇시스템학회:학술대회논문집
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    • 1999.10a
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    • pp.37-40
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    • 1999
  • ETRI has successfully completed and delivered to KARI the KOMPSAT Mission Control System. This system was designed to work in the conventional TT&C modulation scheme with the pre-assigned frequencies. As a way to accelerate in catching up with future TT&C technology evolutions, a preliminary study needs to be carried out to prepare for the development of a spread spectrum applicable to TT&C. A brief study was carried out to review some points to be considered in designing and implementing spread spectrum schemes to the ground TT&C system intended for a LEO spacecraft. Also a simulation and link design revisit was performed to see the operational and technical benefits with the KOMPSAT TT&C parameters. An experiment concept is proposed to test as many functions at a time once the prototype is developed. In this configuration, a ground-model TT&C transponder is connected via LAN to the ETRI-developed KOMPSAT S/W simulator and linked to the KOMPSAT TM/TC processing s/w via spread spectrum signals through a GEO satellite bent-pipe link. A satellite data relay link simulation could be carried out in this configuration.

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Performance Simulation of ACM for Compensating Rain Attenuation in Satellite Link (위성시스템 강우 감쇠 보상을 위한 ACM 성능 시뮬레이션)

  • Zhang, Meixiang;Kim, Sooyoung;Pack, Jeong-Ki;Kim, Ihn-Kyum
    • Journal of Satellite, Information and Communications
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    • v.7 no.3
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    • pp.8-15
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    • 2012
  • Adaptive transmission technique is an effective means to counter-measure rain attenation that is one of the most significant factors degrading link quality in satellite communication systems. This paper introduces a simulator for adaptive transmission technique to compensate rain attenuation. In the simulator, a dynamic rain attenuation model is loaded, which was developed to synthesize Korean rain attenuation dynamics at a frequency band of Ka. It is a Markov chain model with rain attenuation parameters extracted from the rain attenuation data measured per second. In addition, various transmission schemes are embedded so that a user defined simulations can be performed. This paper demonstrates simulation results of adaptive schemes in comprison with fixed schemes, and show the efficiency of the adaptive schemes to compensate the rain attenuation.

Simulator Design and Performance Analysis of Link-K Based Relative Navigation System (한국형전술데이터링크(Link-K) 기반 상대항법 시스템의 시뮬레이터 설계 및 성능분석)

  • Lee, Ju Hyun;Lee, Jin Hyuk;Choi, Heon Ho;Choi, Hyogi;Park, Chansik;Lee, Sang Jeong;Lee, Seung Chan
    • Journal of Advanced Navigation Technology
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    • v.20 no.6
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    • pp.528-538
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    • 2016
  • In this paper, an extend kalman filter based relative navigation algorithm is proposed for Link-K based relative navigation. Link-K is a tactical data link system for joint operation capability upgrade of ROK forces. Link-K is inter-operable with Link-16 and transmit and received information of operations and target. In Link-K communication channel, PPLI message including transmitter position and TOA measurement can be used for relative navigation. Therefore Link-K based relative navigation system can be operated. In this paper, software based simulations were carried out for operational feasibility test and performance verification as error factors of proposed Link-K based relative navigation system.

Constructing Virtual Environment for Flight Simulators based on Digital Map (지리정보를 이용한 비행 시뮬레이터의 가상환경 구축)

  • 유병헌;한순흥
    • Korean Journal of Computational Design and Engineering
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    • v.9 no.2
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    • pp.148-157
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    • 2004
  • Interactive simulators that simulate mechanical systems are being developed for the purpose of performance evaluation of product design, replacement of physical training, and entertainment game. Use of flight simulator is increasing to reduce risk and cost of physical training, and we need virtual environment which covers large area terrain. We need a method that can reduce development cost and construction time of virtual environment that simulate the real environment. There have been attempts to link GIS or remote sensing field with virtual reality. This paper examines a method that helps to construct virtual environment, and attempts to link geographic information with virtual reality. A construction method of virtual environment based on digital map and satellite image has been studied.

A Study on the High Performance TCP over Various Communication Links (다양한 통신 링크에서 고성능 TCP에 관한 연구)

  • Kim, Sang-Mi;Choe, Seon-Wan;Han, Seon-Yeong
    • The KIPS Transactions:PartC
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    • v.9C no.2
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    • pp.197-212
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    • 2002
  • Transmission Control Protocol (TCP) [1] has been tuned as a reliable transfer protocol for traditional networks comprising wired links and stationary hosts with same link characteristics. TCP assumes that congestion in the network be a primary cause for packet losses and unusual delays. TCP performs welt over such networks adapting to end-to-end delays and congestion losses, by standard congestion control mechanisms, such as slow-start, congestion avoidance, fast retransmit and recovery. However, networks with wireless and other lossy links suffer from significant losses due to bit errors and handoffs. An asymmetry network such as ADSL has different bandwidth for both directions. As a result, TCP's standard mechanisms incur end-to-end performance degradation in various links. In this paper, we analyze the TCP problems in wireless, satellite, and asymmetry links, and measure the new TCP mechanisms that are recommended by IETF Performance Implications of Link Characteristics (PILC) WG[2], by using Network Simulator 2 (NS-2).

UAV SAR Target Detection Modeling Using STK (STK를 이용한 UAV SAR 목표물 탐지기법)

  • Hwang, Sung-Uk;Kim, Ah-Leum;Song, Jung-Hwan;Lee, Woo-Kyung
    • Journal of Satellite, Information and Communications
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    • v.4 no.2
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    • pp.12-19
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    • 2009
  • In the modern UAV systems, the role of radar payload has been increasing with its unique performance of day-and-night operation and see-through capability over hidden obstacles. Contrary to the satellite reconnaissance, UAV is expected to provide high resolution target detection and recognition capability while frequent flight missions would deliver enhanced SAR image and local information over the target area. STK(Satellite Tool Kit) is a professional space-analysis software widely used in all phases of a space system's life cycle. The simulation of STK is efficient and accurate relatively. In this paper, the author attempt to model the UAV operation and measure the expected SAR image quality. STK(Satellite Tool Kit) is employed to analyze UAV operation and produce SAR raw data. A SAR simulator is developed to produce high resolution SAR image for various ground targets.

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Heterogeneous Network Gateway Architecture and Simulation for Tactical MANET (전술 에드혹 환경에서 이종망 게이트웨이 구조 및 시뮬레이션 연구)

  • Roh, Bong Soo;Han, Myoung Hun;Kwon, Dae Hoon;Ham, Jae Hyun;Yun, Seon Hui;Ha, Jae Kyoung;Kim, Ki Il
    • Journal of the Korea Society for Simulation
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    • v.28 no.2
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    • pp.97-105
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    • 2019
  • The tactical mobile ad-hoc network(MANET) consists of distributed autonomous networks between individual ground nodes, which is effective in terms of network survivability and flexibility. However, due to constraints such as limited power, terrain, and mobility, frequent link disconnection and shadow area may occur in communication. On the other hand, the satellite network has the advantage of providing a wide-area wireless link overcoming terrain and mobility, but has limited bandwidth and high-latency characteristic. In the future battlefield, an integrated network architecture for interworking multi-layer networks through a heterogeneous network gateway (HNG) is required to overcome the limitations of the existing individual networks and increase reliability and efficiency of communication. In this paper, we propose a new HNG architecture and detailed algorithm that integrates satellite network and the tactical MANET and enables reliable data transfer based on flow characteristics of traffic. The simulations validated the proposed architecture using Riverbed Modeler, a network-level simulator.