• Title/Summary/Keyword: network time-delay

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Analysis of the Traffic Characteristics for MAP Network Management System (MAP 네트워크 관리 시스템의 트래픽 분석)

  • 김중규;이용두;이상배
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.19 no.3
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    • pp.434-441
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    • 1994
  • In this paper, performance of MAP management system traffic is analyzed, to realize the network management function in automated manufacturing network mini-MAP. The network management system, which controls and supervises the network resources in the communication network, is the function that is necessarily required in this network. Since the real time response must be required in the Mini-MAP network, the delay performance of the network needs to be analyzed. By means of both analytical method and simulation for cyclic queueing model, the delay time distributions due to the increasement of transmission data are obtained in the implemented management network where SLAM II package is used for simulation. In addition, the parameters of the management function affecting the transmission delay are considered so that these parameters can be used to implement network management system.

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Tracking Control using Disturbance Observer and ZPETC on LonWorks/IP Virtual Device Network (LonWorks/IP 가상 디바이스 네트워크에서 외란관측기와 ZPETC를 이용한 추종제어)

  • Song, Ki-Won
    • Journal of the Institute of Electronics Engineers of Korea SC
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    • v.44 no.1
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    • pp.33-39
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    • 2007
  • LonWorks over IP (LonWorks/IP) virtual device network (VDN) is an integrated form of LonWorks device network and IP data network. LonWorks/IP VDN can offer ubiquitous access to the information on the factory floor and make it possible for the predictive and preventive maintenance on the factory floor. Timely response is inevitable for predictive and preventive maintenance on the factory floor under the real-time distributed control. The network induced uncertain time delay deteriorates the performance and stability of the real-time distributed control system on LonWorks/IP virtual device network. Therefore, in order to guarantee the stability and to improve the performance of the networked distributed control system the time-varying uncertain time delay needs to be compensated for. In this paper, under the real-time distributed control on LonWorks/IP VDN with uncertain time delay, a control scheme based on disturbance observer and ZPETC(Zero Phase Error Tracking Controller) phase lag compensator is proposed and tested through computer simulation. The result of the proposed control is compared with that of internal model controller (IMC) based on Smith predictor and disturbance observer. It is shown that the proposed control scheme is disturbance and noise tolerant and can significantly improve the stability and the tracking performance of the periodic reference. Therefore, the proposed control scheme is well suited for the distributed servo control for predictive maintenance on LonWorks/IP-based virtual device network with time-varying delay.

Implementation of Networked Control System using a Profibus-DP Network

  • Lee, Kyung-Chang;Lee, Suk
    • International Journal of Precision Engineering and Manufacturing
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    • v.3 no.3
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    • pp.12-20
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    • 2002
  • As numerous sensors and actuators are used in many automated systems, various industrial networks are adopted for real-time distributed control. In order to take advantages of the networking, however, the network implementation should be carefully designed to satisfy real-time requirements considering network induced delays. This paper presents an implementation scheme of a networked control system via Profibus-DP network fur real-time distributed control. More specifically, the effect of the network induced delay on the control performance is evaluated on a Profibus-DP testbed. Also, two conventional PID gain tuning methods are slightly modified fur fouling controllers fur the networked control system. With appropriate choices for gains, it is shown that the networked control system can perform almost as well as the traditional control system.

Handoff Algorithm based on One-way Trip Time for Wireless Mesh Network (Wireless Mesh Network을 위한 OTT 기반 핸드오프 알고리즘)

  • Park, Cha-Hee;Yoo, Myung-Sik
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.44 no.5
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    • pp.16-24
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    • 2007
  • Wireless mesh network extends the limited coverage of conventional wireless service from one-hop access point to wider area. It is recognized as an important issue to provide seamless handoff in the wide coverage of wireless mesh network. A long handoff delay may cause high packet loss and disconnection of service, degrading the network performance. The handoff delay is mainly introduced from the channel scanning process obtaining information to make handoff decision and the unnecessary handoffs due to inaccurate handoff decision. In this paper, we propose the handoff algorithm based on one-way trip time (OTT) to expedite the handoff procedure. As compared to the handoff algorithm based on the receiving signal power, the proposed algorithm takes advantage of OTT to obtain the necessary handoff information in a relatively shorter time and reduce the unnecessary handoffs. The performance of proposed algorithm is evaluated through the simulations. It is verified that the proposed handoff algorithm can effectively enhance the handoff accuracy, and therefore reduce the handoff delay and unnecessary handoffs.

An Efficient Retransmission of Multimedia Packet Using Network Analysis (네트워크 상태 분석을 통한 효율적인 멀티미디어 패킷 재전송)

  • 최정용;윤희돈;이근영
    • Proceedings of the IEEK Conference
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    • 2001.06c
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    • pp.93-96
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    • 2001
  • In this paper, we propose a delay-constrained retransmission method to control packet error or loss in common internet. The Delay Regulator(or Jitter Buffer) which is used to control errors caused by unreliable UDP connection, stores received data packets fDr a small amount of time to prevent network jitter from affecting display quality, which causes constant delay. In this paper, we propose a retransmission method to increase efficiency of ARQ(Automatic Repeat reQuest) by using characteristic of delay regulator.

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Obstacle Avoidance Algorithm for a Network-based Autonomous Mobile Robot

  • Sohn, Sook-Yung;Kim, Hong-Ryeol;Kim, Dae-Won;Kim, Hong-Seok;Lee, Ho-Gil
    • 제어로봇시스템학회:학술대회논문집
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    • 2004.08a
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    • pp.831-833
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    • 2004
  • In this paper, an obstacle avoidance algorithm is proposed for a network-based robot considering network delay by distribution. The proposed algorithm is based on the VFH(Vector Field Histogram) algorithm, and for the network-based robot system, in which it is assumed robot localization information is transmitted through network communication. In this paper, target vector for the VFH algorithm is estimated through the robot localization information and the measurement of its delay by distribution. The delay measurement is performed by time-stamp method. To synchronize all local clocks of the nodes distributed on the network, a global clock synchronization method is adopted. With the delay measurement, the robot localization estimation is performed by calculating the kinematics of the robot. The validation of the proposed algorithm is performed through the performance comparison of the obstacle avoidance between the proposed algorithm and the existing VFH algorithm on the network-based autonomous mobile robot.

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Development of an Extended EDS(Earliest Deadline Scheduling) Algorithm for the CAN-Based Real-Time System (CAN기반 실시간 시스템을 위한 확장된 EDS 알고리즘 개발)

  • Lee, Byong-Hoon;Kim, Hong-Ryeol;Kim , Dae-Won
    • The Transactions of the Korean Institute of Electrical Engineers D
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    • v.51 no.7
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    • pp.294-301
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    • 2002
  • A new dynamic scheduling algorithm is proposed for CAN-based real-time system in this paper. The proposed algorithm is extended from an existing EDS(Earliest Deadline Scheduling) approach having a solution to the priority inversion. Using the proposed algorithm, the available bandwidth of network media can be checked dynamically, and consequently arbitration delay causing the miss of deadline can be avoided. Also, non-real time messages can be processed with their bandwidth allocation. Full network utilization and real-time transmission feasibility can be achieved through the algorithm. To evaluate the performance of algorithm, two simulation tests are performed. The first one is transmission data measurement per minute for periodic messages and the second one is feasibility in the system with both periodic messages and non-real time message.

Latency Analysis of AVB Network and Optimization Design for Automotive

  • An, Byoungman;Kim, YoungSeop
    • Journal of the Semiconductor & Display Technology
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    • v.18 no.3
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    • pp.127-132
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    • 2019
  • This paper presents an overview of automotive communication technologies, including related technology developments. We describe the latency of Audio Video Bridge (AVB) network as well as purpose the optimized design of the Ethernet network system for automotive. Our design plays a significant role in reducing the delay between components. The proposed approach on realistic test cases showed that there was a delay reduction, approximately 49.4%. It is expected that the optimization method for the actual automotive environment can greatly shorten the time period in the design and development process. The results obtained from the experiments on the delay time present in each function are reliable because average values are obtained through repeated actual tests for several months. It will greatly benefit the industry since analyzing the latency between each function in a short period of time is very important.

Speech Recognition Method under Noisy Environments using Time-Delay Neural Network (시간지연신경회로망을 사용한 잡음 중의 음성인식 수법)

  • Choi, Jae Seung
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2009.05a
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    • pp.711-714
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    • 2009
  • 잡음환경 하의 회화에서 잡음량을 줄이고 신호처리 시스템의 성능을 향상시키기 위해서는 잡음량에 따라서 적응적으로 처리되는 신호처리 시스템이 필요하다. 또한 잡음이 중첩된 음성으로부터 잡음을 제거하기 위해서는 잡음의 크기에 따라서 음성 처리 시스템의 파라미터를 변경하는 것이 양호한 음질의 음성을 재생하는데 바람직하다. 따라서 본 논문에서는 음성 속에 포함되는 잡음량을 인식하는 방법으로 선형예측계수를 구하여 시간지연신경회로망(Time-delay neural network: TDNN)의 입력으로 사용하여 학습시키는 잡음량을 인식하는 방법을 제안한다. 본 잡음량 인식은 다양한 배경잡음에 의하여 열화된 3종류의 음성이 TDNN에 의하여 학습되어진다. 본 실험에서는 Aurora2 데이터베이스를 사용하여 여러 잡음에 대하여 양호한 인식결과를 확인할 수 있었다.

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A study on the fairness ring protocol for high-speed networks (고속 통신망을 위한 공정성 링 프로토콜에 관한 연구)

  • 김동윤;송명렬;장민석
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.22 no.1
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    • pp.139-150
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    • 1997
  • For high-speed networks, a new ring protocal is proposed in this paper. A ring network combined with destination removal can achieve much higher network throughput than the channel transmission rate. However, such a network exhibits fairness problems. Over a past few years, global fairness algorithms such as ATMR and Metaring have been proposed to solve such problems. But the ring access time delay and fairness in such networks are sensitive to the network parameters such as network size and traffic distribution. In addition to guaranteeing fair ring access to all nodes, there are several other important performance aspects in such networks. The one is that fairness is enforced while node throughputs are kept as high as possible. And another performance measure is access delay and more specifically Head-Of-Line(HOL) delay, i.e., the amount of time the first cell in the transmission buffer of a node has to wait before it accesses the ring. HOL delay is a mijor component in the transmission jitter of the synchronous traffic transmission. A key idea of the proposed ring protocol is to find the nodes that have much more chances to access the ring than any other nodes in the independently distributed node architecture. Since destined by many cells need to share a part of the bandwidths with the next node for the fairness in as much as performance degradation does not become critical. To investigate the performance behavior of the proposed ring protocol for various network condition,s several performance parameters wuch as ring access time delay, and throughput are compared with those of the ATMR and Metaring protocols using simulation package, SIMAN.

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