• Title/Summary/Keyword: ACK기반

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Implementation & Analysis of SAN based on UDP for Cluster Web Server (클러스터 웹서버를 위한 UDP/IP기반 SAM의 구현 및 성능 분석)

  • 이주평;박규호
    • Proceedings of the Korean Information Science Society Conference
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    • 2002.10e
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    • pp.532-534
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    • 2002
  • 본 논문에서는 UDP/IP기반 SAN의 구현을 소개하였고 TCP/IP기반 SAN 및 로컬디스크와의 성능 비교를 통해 UDP/IP기반 SAN이 클러스터 웹서버에서 사용될 수 있는 가능성을 보였다. 실험결과 UDP/IP기반 SAN은 TCP/IP기반 SAN의 경우보다 약 20%정도 성능이 우수함을 볼 수 있다. 이는 UDP의 경우 TCP의 프로토콜 오버헤드가 없고 slow start의 영향을 받지 않으며 ACK를 기다릴 필요가 없기 때문이다.

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Efficient and Scalable Overlay Multicast Mechanism for Real-time Tree Construction (효율적이고 확장성 있는 실시간 트리 구성을 위한 오버레이 멀티캐스트 메커니즘)

  • Nam, Yun-Seung;Im, Dong-Gee;Yang, Hyun-Jong;Nam, Ji-Seung
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.34 no.12B
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    • pp.1399-1406
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    • 2009
  • In the internet broadcast, efficient and scalable mechanism of multicast is needed for the communication between groups. Furthermore, Optimization of the multicast tree is required to improve the performance of overlay multicast. This optimization is well-known as NP-complete. If a node in the tree has limited out-degree, a user who wants to join the group has to find parent user who has already joined. In this paper, the users who want to join the group need to setup their level using delay test from source node. And then new users can find candidate parent nodes effectively using ACK-SEND approach and take proper position by comparing level. The closer node of the user to root node should be located in lower level. Also, even if a barrier is caused, fast recovery will be guaranteed using ACK-SEND approach. Through this, the newcomer node can fine their location in the multicast tree and join the group fast and effectively.

Adaptive Error Control Based on Traffic Type and Channel Error Rate in Wireless ATM (무선 ATM에서의 트래픽 형태 및 채널 오율에 기반한 적응 오류 제어)

  • 김영웅;조동호
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.24 no.10A
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    • pp.1532-1538
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    • 1999
  • In general, because error rate of wireless link is higher than that of wired link, DLC layer protocol for wired network with low error rate is not proper for wireless environments. In addition, the conventional DLC layer protocol for wireless network is optimized for the low-speed data service, so it is difficult to use conventional DLC protocol in the current mobile communication environments handing high-speed and multimedia services. Therefore, a DLC layer protocol that is suitable to current wireless communication environments is required. In this paper, we propose a novel error control scheme that supports a variety of traffic attribute and is applicable to high-speed and multimedia data service in WATM. The proposed scheme provides enhanced throughput performance for real-time traffic by using modified ASR ARQ without ACK and reduces loss rate by using FEC in the case of high error condition. Also, for non real-time traffic, the use of ASR ARQ without ACK enhances throughput performance and delay time is decreased by using FEC in the case of high error rate channel. As a result of simulation, the proposed scheme has better performance than conventional ASR ARQ protocol in view of delay and throughput.

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Performance Evaluation of Common Feedback Channels for Multicast Transmission and Optimization of System Parameters (멀티캐스트 전송을 위한 공용 피드백 채널의 성능 분석 및 파라미터 최적화 설계 방법)

  • Jung, Young-Ho;Kim, Byung-Gun
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.34 no.5B
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    • pp.489-497
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    • 2009
  • In the 3GPP LTE and IEEE 802.16m standardizations for IMT-Advanced, the efficient transmission of multicast and broadcast data is one of the important issues to improve system performance. Especially, to guarantee each user's QoS in the multicast group, H-ARQ or adaptive modulation are considered to be adoption, however, reduction of feedback overhead is one of the most important issues. In this paper, performance of the previously proposed OOK (On-Off Keying) based common ACK/NACK feedback channel is analyzed through theoretical analysis and simulation. Based on the results, system parameter optimization methods for common feedback channel are proposed. In addition, through computer simulation, it is shown that the common feedback method according to the proposed feedback parameter optimization can feedback ACK/NACK information for multicast H-ARQ transmission, more reliably than the conventional user dedicated feedback method in 3GPP LTE systems, and can reduce the feedback overhead as well.

A Design of Hop-by-Hop based Reliable Congestion Control Protocol for WSNs (무선 센서 네트워크를 위한 Hop-by-Hop 기반의 신뢰성 있는 혼잡제어 기법 설계)

  • Heo Kwan;Kim Hyun-Tae;Yang Hae-Kwon;Ra In-Ho
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2006.05a
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    • pp.442-445
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    • 2006
  • In Wireless Sensor Networks(WSNs), a sensor node broadcasts an acquisited data to neighboring other nodes and it makes serious data duplication problem that increases network traffic loads and data loss. This problem is concerned with the conflict condition for supporting both the reliability of data transfer and avoidance of network congestion. To solve the problem, a reliable congestion control protocol is necessary that considers critical factors affecting on data transfer reliability such as reliable data transmission, wireless loss, and congestion loss for supporting effective congestion control in WSNs. In this paper, we proposes a reliable congestion protocol, ratted HRCCP, based on hop-hop sequence number, and DSbACK by minimizing useless data transfers as an energy-saved congestion control method.

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Early Rate Adaptation Protocol in DiffServ for Multimedia Applications (멀티미디어 서비스를 위한 DiffServ 망에서의 빠른 혼잡 제어 알고리즘)

  • Park Jonghun;Yoo Myungsik
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.30 no.1B
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    • pp.39-46
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    • 2005
  • As the multimedia application traffic takes more portion in the internet traffic, it is necessary to control the network congestion through the congestion control protocol. In addition, the QoS-enabled networks such as DiffServ become an indispensable technology when running the multimedia applications. However, the previously proposed end-to-end congestion control algorithms take the round trip time to react the network congestion. Thus, as the RTT becomes larger, the reaction against the congestion gets delayed further, while the network congestion gets worse. In addition the performance of end-to-end congestion control algorithm is degraded if the QoS-enabled network runs the congestion control mechanism in the network level without any coordination between them. In this paper, we propose the early rate adaptation protocol for the DiffServ network which effectively linke the congestion control algorithm at the host and the congestion mechanism in the network together. By taking advantage of early congestion notification from the network it is possible to react the network congestion more quickly and effectively.

The network efficiency improvement which uses the Snoop and Received signal strengths over wired-wireless networks (유무선 혼합 망에서 Snoop과 수신신호(received signal strengths)의 상호관계를 통한 네트워크 성능 개선)

  • Kim Jin-Hee;Kwon Kyung-Hee
    • Proceedings of the Korea Information Processing Society Conference
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    • 2006.05a
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    • pp.1151-1154
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    • 2006
  • 다양한 무선 네트워킹의 출현은 유무선 혼합형태의 네트워크 망으로 변화되면서 기존의 유선 중심의 네트워크 기반으로 구현된 TCP에 많은 문제점을 가져왔다. 높은 비트오류율, 낮은 대역폭 그리고 높은 지연 등은 TCP/IP 통신을 효율적으로 지원하지 못하는 원인이 된다. 또한 BS(Base Station:기지국)에서 보낸 패킷이 MH(Mobile Node : 이동성을 갖는 노드)가 수신범위 밖으로 벗어나면서 손실로 이어질 경우 성능 저하의 원인이 되기도 한다. 본 논문에서는 MN의 ACK에 수신신호 관련 flag bit를 추가하면서 BS에서 추가된 ACK의 flag bit를 이용해서 패킷손실을 최소화하는 기법을 제안한다.

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Distributed Real-time Simulation for the performance analysis of Fault Detector (고장 탐지 방법의 성능 분석을 위한 분산 실시간 시뮬레이션)

  • 노진홍;홍영식
    • Proceedings of the Korean Information Science Society Conference
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    • 2002.04a
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    • pp.82-84
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    • 2002
  • 신뢰성이 높은 분산 시스템은 고장 발생 시 고장을 탐지하고, 다른 관련된 노드들에게 고장을 알려주어서 적절한 처리를 할 수 있어야 한다. 기존의 act 와 time-out 을 사용한 고장 탐지방법은 수신되지 않는 ack 에 대한 부하가 높은 단점을 가지고 있다. 높은 신뢰성을 요구하는 분산 실시간 시스템에서는 데드라인을 준수하기 위해 고장처리에 대한 time-bound 를 결정할 수 있어야 하므로, 기존의 ack 와 time-out 에 기반한 고장방법을 사용하기에 부적절하다. 따라서 본 논문에서는 신뢰성 있는 분산 실시간 멀티캐스트 프로토착에 결합된 고장 탐지 기법으로서 사용될 기존의 고장 탐지 방법을 대상으로 고장 탐지 방법을 실험하고, 그 결과를 분석하여 고장탐지 및 고장처리 지연시간이 데드라인을 보장할 수 있는지 검사한다.

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Traffic Performance Analysis using Asymmetry Wireless Link Network in Transmission Rate Controlled Channels (전송률 제어 채널에서 비대칭 무선 링크 네트워크를 이용한 트래픽 성능 분석)

  • Jeong, You-Sun;Youn, Young-Ji;Shin, Bo-Kyoung;Kim, Hye-Min;Park, Dong-Suk;Ra, Sang-Dong
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.12 no.8
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    • pp.1434-1440
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    • 2008
  • Performance of TCP/IP is studied on the wireless network using flow control and congestion control mechanism based on transmission rate. We discuss the elimination or the reduction of various phenomena of burst by flow controlling on transmission rate and verify that there are TCP ACK compression promblems on the queue by burst reaction while executing transmission rate controlled channels. Analyzing periodic burst reaction on the queue of source IP, the maximum value of queue is expected, which represents the applible expectation of throughput reduce and shows the improvement of performance by the reduce of throughput due to hi-directional traffic.

A Design of Hop-by-Hop based Reliable Congestion Control Protocol for WSNs (무선 센서 네트워크를 위한 Hop-by-Hop 기반의 신뢰성 있는 혼잡제어 기법 설계)

  • Heo Kwan;Kim Hyun-Tae;Ra In-Ho
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.10 no.6
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    • pp.1055-1059
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    • 2006
  • In Wireless Sensor Networks(WSNs), a sensor node broadcasts the acquisited sensing data to neighboring other nodes and it makes serious data duplication problem that increases network traffic loads and data loss. This problem is concerned with the conflict condition for supporting both the reliability of data transfer and avoidance of network congestion. To solve the problem, a reliable congestion control protocol is necessary that considers critical factors affecting on data transfer reliability such as reliable data transmission, wireless loss, and congestion loss for supporting effective congestion control in WSNs. In his paper, we proposes a reliable congestion protocol, called HRCCP, based on hop-hop sequence number, and DSbACK by minimizing useless data transfers as an energy-saved congestion control method.