• Title/Summary/Keyword: 상태 상향전송

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Analysis of Data Rate on Optical Communication Links between Geo-Satellite and Earth Station (정지궤도 위성과 지구국간 광통신 링크의 전송속도 해석)

  • Han, Jong-Seok;Jung, Jin-Ho;Kim, Yung-Kwon
    • Journal of IKEEE
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    • v.1 no.1 s.1
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    • pp.120-137
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    • 1997
  • Han's model, which is able to analyze optical communication between earth station and geo-satellite as a function of atmospheric conditions and elevation angles. is presented. In Han's model, atmospheric conditions are roughly classified into six basic types; clear sky, cloud, haze, fog, rain and snow. Data rate satisfying for the BER below $10^{-7}$ is analyzed by Han's model in case of up-link and down-link, respectively. Data rate is more limited by up-link than by down-link because the pointing loss caused by atmosphere on the up-link is greater than the spatial coherence degradation caused by atmosphere on the down-link.

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A Dynamic ACK Regeneration Scheme to Improve TCP Performance over Asymmetric Networks (비대칭 망에서 TCP 성능 향상을 위한 동적 응답 패킷 재생성 기법)

  • Ahn, Joon-Chul;Lee, Ji-Hyun;Lim, Kyung-Shik
    • Proceedings of the Korean Information Science Society Conference
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    • 2005.07a
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    • pp.562-564
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    • 2005
  • 비대칭 율이 높은 비대칭 망에서 동작하는 TCP의 성능은 상향 링크의 혼잡 발생 여부에 좌우된다. 상향 링크에 실리는 응답 패킷 트래픽이 링크의 대역폭을 넘어서게 되면 응답 패킷이 손실되거나 전송 지연이 길어져서 성능을 저하시킨다. 상향 링크의 혼잡 문제를 해결하는 대표적인 방법으로 응답 패킷 필터링/재생성 기법을 들 수 있다. 본 논문에서는 해당 기법의 문제점을 해결한, 송신측 TCP의 상태에 따라 응답 패킷 재생성 작업을 수행하는 동적 패킷 재생성 기법을 제안한다. 이 기법은 정확한 응답 패킷을 재생성하고, 이를 순서 뒤바뀜 없이 송신측에 전송하도록 하여 혼잡 제어 구간에서의 성능을 향상시킨다. 또, TCP가 혼잡 제어 상태에 있는 동안에만 응답 패킷 재생성 작업을 수행하도록 하여 불필요한 응답 패킷 트래픽과 패킷 재생성에 드는 부하를 줄인다.

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Synch. RA-based Uplink Packet Transmission in OFDMA Systems (OFDMA 시스템에서 동기 RA 방식 기반의 상향링크 패킷 전송)

  • Oh, Sang-Kyu;Moon, Jin-Soo;Shin, Seok-Joo
    • Journal of Internet Computing and Services
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    • v.9 no.2
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    • pp.25-33
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    • 2008
  • In this paper we propose uplink packet transmission scheme based on Synchronized RA. The scheme can afford to support diverse QoS required from diverse multimeda traffics. In order to minimze the collision probability occurred in contention based channel access, we assign a reservation access channel additionally to the traffic channels. Access probability function for controlling collisions occurred in the reservation access channel is applied. Through assigning different access probability to each traffic user with respect to priority issued by his required QoS, the proposed scheme guarantees minimum throughput required by higher priority users in the whole range of system load.

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Dynamic Bandwidth Allocation Scheme with Considering Downstream Traffic in EPON (EPON에서 하향 데이터 전송을 고려한 동적 대역폭 할당 방안)

  • Kim Eun-Chul;Lee Kang-Won;Choi Young-Soo;Cho You-Ze
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.42 no.12
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    • pp.37-44
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    • 2005
  • This paper proposes a hybrid scheme for dynamic bandwidth allocation(DBA) in Ethernet passive optical network(EPON), which combines advantages of adaptive cycle and constant cycle-based schemes. The proposed scheme is based on IPACT scheme, but it operates as adaptive cycle or constant cycle mode according to the queue status of optical line terminal(OLT) for downstream transmission. Simulation results showed that the proposed scheme could achieve a similar throughput in downstream transmission to a constant cycle-based DBA scheme, while producing a similar delay performance to the IPACT scheme in upstream transmission.

Differential Bandwidth Allocation Method using Upstream Bandwidth Wavelength Division of EPON (상향트래픽 파장분할 EPON에서 우선순위 큐를 고려한 차등대역폭 할당방법)

  • Seo, Chang-Jin;Jang, Yong-Suk
    • Journal of Digital Convergence
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    • v.10 no.4
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    • pp.265-270
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    • 2012
  • The subscriber access network is cause of the bottleneck phenomenon because equipment and infrastructure were not originally designed for busty high-bandwidth traffic between MAN(Metro Area Network) and LAN(Local Area Network). Whether riding on shorter copper drops or optical fiber, Ethernet is emerging as the future broadband protocol of choice, offering plug and play simplicity, and low cost. EPON(Ethernet Passive Optical Network) combines point-to-multipoint optical infrastructure with low-cost high-bandwidth Ethernet. The future broadband access network will be a combination of point-to-point and point-to-multipoint Ethernet, optimized for transporting IP data, as well as time critical voice and video. EPON is being considered as a novel communications infrastructure for next-generation broadband access network for the convergence of low-cost Ethernet equipment and low-cost fiber infrastructure. But, EPON has a problem with duplex multimedia services. It is the insufficiency of bandwidth for upstream. Because all ONUs use a shared transmission media for upstream. In this paper, we addressed the problem of upstream bandwidth in EPONs. We presented a wavelength division EPON supporting QoS in the differentiated services framework.

Efficient Uplink Resource Allocation for Power Saving in IEEE 802.16 OFDMA Systems (파워 절약을 위한 IEEE 802.16 OFDMA 시스템의 효율적 상향링크 자원 할당 알고리즘)

  • Yoon, Jong-Pil;Kim, Woo-Jae;Baek, Joo-Young;Suh, Young-Joo
    • Proceedings of the Korean Information Science Society Conference
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    • 2007.10d
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    • pp.407-412
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    • 2007
  • 본 논문에서는 IEEE 802.16 OFDMA 시스템에서 단말들의 에너지 절약을 위한 효율적인 상향 링크 자원 할당 알고리즘을 제시한다. 기지국은 각각의 단말들이 상향링크로 데이터를 전송할 수 있도록 상향링크 부프레임에 연속적인 형태의 자원을 할당해 줘야 한다. 이렇게 각 단말들의 에너지 소비를 고려하여 효율적으로 자원을 할당하는 방식은 최적화 문제의 형태로 접근할 수 있다. 본 논문에서는 전체 에너지소비가 최소가 되는 자원 할당 문제를 Multiple Choice Knapsack 문제로 정의하고, 이를 효율적으로 풀 수 있는 준최적화 알고리즘을 제시한다. 준최적화 알고리즘은 전체 에너지 소비가 최소가 되는 각 단말들의 최적의 변조로 부호화 기법을 찾는다. 그리고 성능평가를 통해 준최적화 알고리즘이 채널 상태만을 고려하여 변조로 부호화 레벨을 결정하는 기법에 비해 최대 53%의 성능 이득을 보이는 것을 제시한다.

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Uplink Congestion Control over Asymmetric Networks Using Segment Size Control (비대칭 망에서 세그먼트 크기 조정을 통한 상향 링크의 혼잡 제어)

  • Park Hyungyu;Je Jungkwang;Ahn Joonchul;Lim Kyungshik
    • Proceedings of the Korean Information Science Society Conference
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    • 2005.07a
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    • pp.565-567
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    • 2005
  • 상향 링크와 하향 링크의 대역폭이 다른 비대칭 망 환경에서 범용 TCP를 사용하는 경우, 상향 링크의 혼잡으로 인해 TCP의 성능이 저하되는 문제점이 있다. 본 논문에서는 이러한 문제점을 개선하기 위하여 하향 링크에서 데이터 세그먼트의 크기를 조정하여 상향 링크의 혼잡을 완화시키는 방법을 제안한다. 이 방법은 단대단 의미구조를 유지하면서 망의 상태에 따라 세그먼트의 크기를 최적으로 조절하여 응답 패킷을 최소한으로 생성하도록 하는 특징을 가지고 있다. 특히, 조정된 크기를 갖는 세그먼트가 전송 도중에 오류가 발생하는 경우에 빠른 복구를 위해 SACK를 사용한다. 또한, 혼잡 제어 구간에서는 세그먼트의 크기를 조절하지 않도록 하여 줄어든 응답 패킷의 수로 인한 성능 감소를 방지한다.

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Improved ErtPS Scheduling Algorithm for AMR Speech Codec with CNG Mode in IEEE 802.16e Systems (IEEE 802.16e 시스템에서의 CNG 모드 AMR 음성 코덱을 위한 개선된 ErtPS 스케줄링 알고리즘)

  • Woo, Hyun-Je;Kim, Joo-Young;Lee, Mee-Jeong
    • The KIPS Transactions:PartC
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    • v.16C no.5
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    • pp.661-668
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    • 2009
  • The Extended real-time Polling Service (ErtPS) is proposed tosupport QoS of VoIP service with silence suppression which generates variable size data packets in IEEE 802.16e systems. If the silence is suppressed, VoIP should support Comfort Noise Generation (CNG) which generates comfort noise for receiver's auditory sense to notify the status of connection to the user. CNG mode in silent-period generates a data with lower bit rate at long packet transmission intervals in comparison with talk-spurt. Therefore, if the ErtPS, which is designed to support service flows that generate data packets on a periodic basis, is applied to silent-period, resources of the uplink are used inefficiently. In this paper, we proposed the Improved ErtPS algorithm for efficient resource utilization of the silent-period in VoIP traffic supporting CNG. In the proposed algorithm, the base station allocates bandwidth depending on the status of voice at the appropriate interval by havingthe user inform the changes of voice status. The Improved ErtPS utilizes the Cannel Quality Information Channel (CQICH) which is an uplink subchannel for delivering quality information of channel to the base station on a periodic basis in 802.16e systems. We evaluated the performance of proposed algorithm using OPNET simulator. We validated that proposed algorithm improves the bandwidth utilization of the uplink and packet transmission latency

Improvement and Performance Evaluation of Uplink Scheduling Method for the High-speed Portable Internet System (휴대인터넷에서 상향링크 스케줄링 방법의 개선 및 성능 평가)

  • Kim, Kyung-Hee;Baek, Jang-Hyun
    • Journal of the Korea Society for Simulation
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    • v.15 no.2
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    • pp.41-50
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    • 2006
  • The high-speed portable internet service will be served in Korea sooner or later. However, the scheduling method for the packets of various service classes has not been determined clearly yet. An effective packet scheduling for various service classes requiring different QoS is necessary to increase the efficiency of radio channels that are the limiting resource. This paper proposes an improved uplink scheduling method to accommodate more calls and enhance channel efficiency. Suggested scheduling method reflects different channel conditions considering terminal's location within a cell to increase the transmission rate and utility of the channels. According to our simulation results, our proposed scheduling method shows a good performance in the aspect of throughput and capacity of uplink channels.

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Method of DNC System Communication for FMS Construction (FMS 구축을 위한 DNC 시스템 통신기법)

  • 이석희;배용환
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.18 no.4
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    • pp.805-815
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    • 1994
  • The development of automatic production systems has a trend toward Computer Integrated Manufacturing System(CIMS) in recent years. In hardware configuration, CIMS are composed of intelligent CAD/CAM work stations, multifunction CNC machining centers including material handling systems. The DNC systems present the key element of automation hierarchy in a FMS. A DNC system is one which connects a number of numerically-controlled machines to a common memory in a digital computer for part program storage with provision for on-demand distribution of part program data to machines using communication in hierarchical structure of central computer, control computer and cell controller. This paper describes the development of Behind-the-Tape-Reader(BTR) type DNC system using CYBER 180-830 as a central computer and IBM PC-386 cell control computer and NC lathe with FANUC 5T NC controller. In this system, the connection between central computer and cell control computer is done via RS-232C serial interface board, and the connection between cell control computer and FANUC 5T controller is done via parallel interface board. The software consists of two module, central computer communication module for NC program downloading and status uploading, NC machine running module for NC operating.