• Title/Summary/Keyword: Satellite Internet

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A Dynamic ACK Generation Scheme to Improve Web Traffic Performance over Satellite Internet (위성 인터넷에서 웹 트래픽의 성능 향상을 위한 동적 응답 패킷 생성 기법)

  • Park, Hyun-Gyu;Lee, Ji-Hyun;Lim, Kyung-Shik;Jung, Woo-Young
    • IEMEK Journal of Embedded Systems and Applications
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    • v.1 no.2
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    • pp.64-72
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    • 2006
  • The long propagation delay over satellite internet causes degradation of TCP performance in slow start phase. Especially, web traffic performance is greatly reduced by low throughput in slow start phase. To improve web traffic performance, we propose the Dynamic ACK Generation Scheme which generates ACKs and considers sender RTO in PEP (Performance Enhancing Proxy). The Normal ACK generation mechanism improves TCP throughput, and also decreases sender RTO. if PEP stops generating ACKs, TCP performance will be reduced by frequent RTO expiration. To solve this problem, our scheme adjusts RTO using ACK generation interval. And it supports retransmission mechanism for loss recovery in PEP. The results of the performance analysis provide a good evidence to demonstrate the efficiency of our mechanisms over satellite internet.

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A Dual-Band Gap-Filler Antenna Design with a Phi-Shaped Slot

  • Park, Sang Yong;Park, Jong Kweon
    • Journal of electromagnetic engineering and science
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    • v.15 no.2
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    • pp.111-114
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    • 2015
  • In this paper, we have proposed dual-band Phi-shaped slot gap filler antenna for satellite internet service applications. Some properties of the antenna such as return loss, radiation pattern, and gain have been simulated and measured. The proposed antenna has a Phi-shaped slot on the circular patch and is fabricated on the TLX-9 substrate. The radius of the circular patch is 25 mm, and it has a coaxial feeding structure. The dual-band Phi-shaped slot gap filler antenna has high-gain, small-size, simple-structure, and good radiation patterns at each band. The operating frequency band can be tuned by adjusting the length AL and FL of the Phi-shaped slot.

A Dual Band Microstrip Antenna with Two Y-Shaped Slots for Satellite Internet Service (위성 인터넷 서비스를 위한 두 개의 Y 형태 슬롯을 가지는 이중 대역 마이크로스트립 안테나)

  • Kim, Byoung-Chul;Lee, Sang-Un;Han, Sung-Min;Lee, Ho-Jin;Choo, Ho-Sung;Park, Ik-Mo
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.19 no.2
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    • pp.145-151
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    • 2008
  • In this paper, a dual band microstrip antenna with similar radiation pattern for the satellite internet service is proposed. The proposed antenna has two Y-shaped slots on the microstrip patch that is fabricated on RO4003 substrate with a dielectric constant of 3.38 and a thickness of 0.508 mm, and operates in the 2 GHz and 5 GHz bands. The size of the antenna is $50\times47.5\times6.5\;mm^3$, and fed by coaxial cable. The measured bandwidths of the antenna are 2.398$\sim$2.507 GHz and 5.458$\sim$5.972 GHz for VSWR<2. The measured gains are 8.92 dBi and 7.74 dBi, respectively, for the lower and upper bands.

Development of Web-based Telemedicine using Satellite Internet Communication System (위성인터넷통신을 이용한 Web 기반 원격의료시스템 개발)

  • Hwang, Seon-Cheol
    • Journal of Internet Computing and Services
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    • v.1 no.1
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    • pp.95-104
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    • 2000
  • In general cases, the conventionl Internet connected to a terrestrial network is too slow to transmit large medical images. To overcome this low speed problem of the Internet, we have developed asymmetric satellite data communication system (ASDCS) as a fast satellite Internet communication method. The ASDCS uses a receive-only satellite link for dat delivery and a terrestrial network for control communication. The satellite communication link we implemented showed the very high-speed performance compared to the terrestrial link. Using ASDCS, the satellite Internet communication was 10-30 times faster than the conventional terrestrial Internet link. Also we have developed a Web-based Telemedicine system that can access every permitted server of hospital via the Internet. Java programming techniques were used to make our system and it can access and retrieve medical information and images through only public web browser such as Netscape TM without additional specific tools. To increase the transmitting speed of our Telemedicine system, JPEG method was used. In conclusion, we were able to develop a fast and public Telemedicine system using the proposed ASDCS and Web technology. ASDCS technology increased the speed of the conventional Internet and Web technology extended the scope of use for Telemedicine system from intrahospital to public use.

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Comparison of Proxy Server Mechanisms in Satellite Internet (위성 인터넷망에서의 프록시 서버 기법 비교)

  • 김용신;김영한;전경재;안재영
    • Proceedings of the IEEK Conference
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    • pp.106-109
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    • 1999
  • 위성 인터넷망에서의 성능 향상을 위한 프록시의 대표적인 기법인 Snoop과 Spoofing에서의 TCP 성능을 모의실험을 통해 비교하고, 전체 메모리 크기에 따른 TCP 전송 특성 변화를 살펴보았다. Spoofing과 Snoop에서 모두 TCP 전송율이 향상됨을 확인할 수 있었고, Spoofing을 적용했을 경우 Snoop보다 높은 전송율을 얻을 수 있었으나 데이터를 저장하기 위한 버퍼 요구량이 매우 커졌다. 메모리 크기는 제한되어 있으므로 효율적인 메모리 분배 방법이 필요함을 고찰할 수 있었다.

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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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    • 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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A Performance Analysis of FEC Coding Method in Rayleigh Satellite Return Link Channel (레일리 위성 리턴링크 채널에서 FEC 부호 방식 성능분석)

  • Lee Seong Ro;Cho Sung Eui;Oh Deock gil
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.29 no.12C
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    • pp.1633-1641
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    • 2004
  • In satellite digital broadcasting and satellite internet, severe burst errors occur in the high-speed return channel from the satellite to mobiles. In this paper, we analyze the performance of the forward error correction (FEC) coding method in the Rayleigh fading return channel. We first investigate the channel model of Loo, LutB, Vucetic and Corazza. We then compare the performance of the convolutional, Reed-Solomon (RS), convolution-RS concatenation, and Turbo codes in rayleigh fading channel.

Core Technology and Service Trends of Multimedia Service Using Satellite (위성을 이용한 멀티미디어 서비스의 요소 기술과 제공 현황)

  • 김정호
    • Journal of the Korean Professional Engineers Association
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    • v.34 no.4
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    • pp.36-40
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    • 2001
  • Multimedia service via satellite Is supported voice, data, Image and video signals. The representation case model of satellite multimedia are satellite TV. satellite Internet. In the early 1990s, satellite communication and broad casting services successfully expanded form C/Ku band to Ka band. The benefits of operation at Ka-band are greater bandwidth available to accommodate the increased demand for high-speed Information exchange. By the early years of the 21s1 century, millions of households worldwide with dual Ku / Ka-band dishes Satellite multimedia systems receive hundreds of TV channels, originating from around the world, and delivering entertainment, information and education. Many Ku-band satellites have been ordered, but few Ka-band systems are moving into production. So Ka-band systems are characterized that low-cost access to low and high peed, two-way voice, data, and video communications.

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A study on policy of VSAT (Very Small Aperture Terminal) license system (소형위성지구국(VSAT)허가 제도에 관한 정책 연구)

  • Oh, Gab-Kuen;Lee, Sang-Yun;Hong, Wan-Pyo
    • Journal of Advanced Navigation Technology
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    • v.13 no.2
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    • pp.172-177
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    • 2009
  • Mugunghwa Satellite N0.1 is fired after operation was 13 years. The establishment of communication satellites, as well as Internet service backbone network the country, including satellite broadcasting services to provide multimedia services to general users and contribute to have a big role. High-speed Internet Access Network was expanded and satellite Internet subscribers Access Network rapidly decreasing, but it also a difficult situation, satellite communications network is still important as a component is located. Launched the first communication satellite to be launched and operated several commercial communications satellite, but satellite communications services and the pace of the system is in place. In this paper VSAT, satellite communications service to provide a service based on the status and problems of the status of operating system and will present alternative policies to solve.

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Economic Analyses on the Satellite Broadband Internet Services for High Speed Trains (고속철도에서의 위성 광대역 인터넷서비스 경제성 분석)

  • Ahn, Jae-Kyoung;Song, Mi-Ja
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.31 no.11B
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    • pp.997-1004
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    • 2006
  • There is a growing demand to access the broadband internet while on the very fast move. In order to meet these users needs, much research has been made for providing the broadband internet and HDTV services via satellite broadband internet systems even at top train speeds above 200km/h. In this paper, economic analyses on the satellite broadband internet services for KTX are to be reviewed. Broadband internet to trains in Europe are investigated, and Boeing cases for planes are also examined. In the first step, system configuration which is composed of a hub, terminals, satellite, and gap fillers for the tunnel areas has been proposed. A terminal includes a ultra-fast high gain antenna installed on the roof of the train, and APs inside the coaches. Secondly, cost estimation on the capital expenditures as well as operating expenditures has been performed in the proposed configuration. From the european and Boeing cases, demand and tariff are postulated, consequently, service revenues are derived on the scenario basis. Thirdly, estimated costs and derived revenues make up net present value and internal rate of return in each scenario. Finally, conclusions and contribution of this study are presented.