• Title/Summary/Keyword: 무선 ATM

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MAC Protocol for Packet Data Service in Slotted CDMA Environment (슬롯 CDMA 환경에서 패킷 데이터 서비스를 위한 MAC 프로토콜)

  • 임인택
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.7 no.7
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    • pp.1399-1405
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    • 2003
  • This paper proposes an MAC protocol for fair packet data services in stoned CDMA system. In slotted CDMA system, the packets transmitted in the same slot act as multiple access interference, so that unsuccessful packet transmissions are entirely caused by multiple access interference. Therefore, in order to get the optimal system throughput, the number of simultaneously transmitted Packets should be kept at a proper level. In the proposed protocol, the base station calculates the new and retransmitted packet transmission probability of mobile stations according to the offered load and then broadcasts these probabilities. Mobile stations, which have a packet, attempt to transmit packet with the received probabilities. Simulation results show that the proposed scheme can offer better system throughput than the conventional scheme, and guarantee a good fairness among all mobile stations regardless of the offered load.

Performance Analysis of WATM-OFDM/l6QAM System in Frequency Selective Rayleigh Fading Channel (주파수 선택성 레일리 페이텅 통신로에서 WATM-OFDM/16QAM 시스템의 성능 분석)

  • 박기식;이영춘;강영흥;김언곤;조성언
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.4 no.3
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    • pp.635-642
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    • 2000
  • We have been derived theoretically the SER's and CLP's of Wireless ATM (WATM) cells employing an OFDM/16QAM modulation scheme in wireless channel modeled as a frequency selective Rayleigh fading channel. The amount of the performance improvement of WATM- OFDM/16QAM systems adopting various coding techniques has been evaluated. In frequency selective Rayleigh fading channel, considering CLP : $10^{-3}$ as a criterion, it is observed that the performance improvement of about 14 dB is obtained in terms of $E_b/N_o$ by employing an OFDM scheme. It is also confirmed that convolutional coding technique gives better performance than the other coding techniques. Especially, when the convolutional codes are adopted to WATM-OFDM/16QAM systems, voice transmission services are sufficiently available with 5 dB of $E_b/N_o$.

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Measure to Introduction of Performance-Based Communication and Surveillance (PBCS) in Korea (국내 성능기반항공통신 및 감시(PBCS) 도입 방안)

  • Hong, Seung-Boem;Choi, Won-Hyuck
    • Journal of Advanced Navigation Technology
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    • v.20 no.4
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    • pp.336-343
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    • 2016
  • Future air navigation system (FANS) Committee overcomes the limitations of traditional systems, the development of worldwide new system that allows the development of air traffic management have been determined to be necessary. In order to accommodate the rapid increase in aircraft traffic and maximize the safe air navigation efficiency, ICAO is recommending a new performance-based communications and surveillance (PBCS) system. However, although utilizing wireless data link in the case of korea currently, the introduction of the PBCS is not performed normally. In this paper, we review the concept of PBCS, and aviation developed countries look to the applied case of PBCS. It also analyzes trends and status and problems of Korea and introduce future policy directions for CNS/ATM system improvement.

A Study on the Performance Improvements of Congestion Control of Multiple Time Scale Under in TCP-MT network (TCP-MT네트워크에서 다중 시간 간격을 이용한 혼잡제어 성능 개선에 관한 연구)

  • Cho, Hyun-Seob;Oh, Myoung-Kwan
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.9 no.1
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    • pp.75-80
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    • 2008
  • Measurement of network traffic have shown that the self-similarity is a ubiquitous phenomenon spanning across diverse network environments. In previous work, we have explored the feasibility of exploiting the long-range correlation structure in a self-similar traffic for the congestion control. We have advanced the framework of the multiple time scale congestion control and showed its effectiveness at enhancing performance for the rate-based feedback control. Our contribution is threefold. First, we define a modular extension of the TCP-a function called with a simple interface-that applies to various flavours of the TCP-e.g., Tahoe, Reno, Vegas and show that it significantly improves performance. Second, we show that a multiple time scale TCP endows the underlying feedback control with proactivity by bridging the uncertainty gap associated with reactive controls which is exacerbated by the high delay-bandwidth product in broadband wide area networks. Third, we investigate the influence of the three traffic control dimensions-tracking ability, connection duration, and fairness-on performance.

A Design and Implementation of an ADS-B Monitoring System Capable of Displaying Air Traffic Situation (항공 교통 상황 종합 현시 기능을 갖는 ADS-B 모니터링 시스템 설계 및 구현)

  • Song, Inseong;Jang, Eunmee;Yoon, Wanoh;Choi, Sangbang
    • Journal of Advanced Navigation Technology
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    • v.18 no.4
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    • pp.278-287
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    • 2014
  • ADS-B is a newly developed air surveillance technology to address the consistently increasing air traffic needs. ADS-B attracts attention for replacing or complementing a conventional radar since ADS-B can provide more accurate position information with a shorter interval when compared to the radar. However, as ADS-B uses wireless data links on exchanging information between an aircraft and a ground ADS-B system, and uses protocols without integrity support on exchanging information within the ground ADS-B system, a system which can monitor the operational status of an ADS-B system is essential. In this work, we design and implement an ADS-B monitoring system capable of displaying air traffic situation that can show the comprehensive air traffic situation while monitoring the operational status of the ADS-B system. The implemented ADS-B monitoring system has been verified with a configured ADS-B ground system by displaying ADS-B surveillance data, radar surveillance data, and flight information after receiving live surveillance data of in flight aircrafts, and virtual flight information data.

Open Services Environment capabilities for NGN Application (NGN 응용을 위한 개방형 서비스 환경 기능)

  • Lee, Won-Suk;Lee, Seung-Yun
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2008.10a
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    • pp.685-688
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    • 2008
  • A Next Generation Network (NGN) is a packet-based network able to provide services including Telecommunication Services and able to make use of multiple broadband, QoS-enabled transport technologies and in which service-related functions are independent from underlying transport-related technologies. It offers unrestricted access by users to different service providers. It supports generalized mobility which will allow consistent and ubiquitous provision of services to users in this paper. we describe the trend of standardization activity related with open services environment capabilities which had been finally approved at September 2008 in ITU-T. ITU-T SG13 is responsible for studies relating to the architecture, evolution and convergence of next generation networks including frameworks and functional architectures, signalling requirements for NGN.

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The Standardization Trend of Open Services in NGN Environment (NGN 환경에서의 개방형 서비스 표준화 동향)

  • Lee Won-Suk;Lee Kang-Chan;Lee Seung-Yun
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2006.05a
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    • pp.978-980
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    • 2006
  • A Next Generation Network (NGN) is a packet-based network able to provide services including Telecommunication Services and able to make use of multiple broadband, QoS-enabled transport technologies and in which service-related functions are independent from underlying transport-related technologies. It offers unrestricted access by users to different service providers. It supports generalized mobility which will allow consistent and ubiquitous provision of services to users In this paper, we explain the trend of standardization activity related with open services in ITU-T SG13(Study Group 13). ITU-T SG13 is responsible for studies .elating to the architecture, evolution and convergence of next generation networks including frameworks and functional architectures, signalling requirements for NGN.

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