• Title, Summary, Keyword: Real-time Data

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A Dynamic Backoff Adjustment Method of IEEE 802.15.4 Networks for Real-Time Sporadic Data Transmission (비주기적 실시간 데이터 전송을 위한 IEEE 802.15.4 망의 동적 백오프 조정 기법에 대한 연구)

  • Lee, Jung-Il;Kim, Dong-Sung
    • Journal of Institute of Control, Robotics and Systems
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    • v.14 no.3
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    • pp.318-325
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    • 2008
  • In this paper, a dynamic backoff adjustment method of IEEE 802.15.4 is proposed for time-critical sporadic data in a noisy factory environment. For this, a superframe of IEEE 802.15.4 is applied to a real-time mixed data (periodic data, sporadic data, and non real-time message) transmission in factory communication systems. To guarantee a channel access of real-time sporadic(non-periodic) data, a transmission method using the dynamic backoff is applied to wireless control networks. For the real-time property, different initial BE, CW parameters are used for the dynamic backoff adjustment method. The simulat-ion results show an enhancement of the real-time performance of sporadic emergency data. The proposed method provides the channel access of real-time sporadic data efficiently, and guarantee real-time transmission simultaneously within a limite-d timeframe.

A transmit function implementation of wireless LAN MAC with QoS using single transmit FIFO (단일 송신 피포를 이용한 QoS 기능의 무선랜 MAC의 송신 기능 구현)

  • Park, Chan-Won;Kim, Jung-Sik;Kim, Bo-Kwan
    • Proceedings of the KIEE Conference
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    • pp.237-239
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    • 2004
  • Wireless LAN Voice over IP(VoIP) equipment needs Quality-of-Service(QoS) with priority for processing real-time traffic. This paper shows transmit function implementation of wireless LAN(WLANs) media access control(MAC) support VoIP, and it has an advantage of guarantee of QoS and is adaptable to VoIP or mobile wireless equipment. The IEEE 802.11e standard in progress has four queues according to four access categories(AC) for transmit and the MAC transmits the data based on EDCA. The value of AC is from AC0 to AC3 and AC3 has the highest priority. The transmit method implemented at this paper ensure QoS using one transmit FIFO in hardware since real-time traffic data and non real-time traffic data has the different priority. The device driver classifies real-time data and non real-time data and transmit data to hardware with information about data type. The hardware conducts shorter backoff and selects faster AIFS slot for real-time data than it for non real-time data. Therefor It make give the real-time traffic data faster channel access chance than non real-time data and enhances QoS.

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Tramsmission Method of Periodic and Aperiodic Real-Time Data on a Timer-Controlled Network for Distributed Control Systems (분산제어시스템을 위한 타이머 제어형 통신망의 주기 및 실시간 비주기 데이터 전송 방식)

  • Moon, Hong-ju;Park, Hong-Seong
    • Journal of Institute of Control, Robotics and Systems
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    • v.6 no.7
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    • pp.602-610
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    • 2000
  • In communication networks used in safety-critical systems such as control systems in nuclear power plants there exist three types of data traffic : urgent or asynchronous hard real-time data hard real-time periodic data and soft real-time periodic data. it is necessary to allocate a suitable bandwidth to each data traffic in order to meet their real-time constraints. This paper proposes a method to meet the real-time constraints for the three types of data traffic simultaneously under a timer-controlled token bus protocol or the IEEE 802.4 token bus protocol and verifies the validity of the presented method by an example. This paper derives the proper region of the high priority token hold time and the target token rotation time for each station within which the real-time constraints for the three types of data traffic are met, Since the scheduling of the data traffic may reduce the possibility of the abrupt increase of the network load this paper proposes a brief heuristic method to make a scheduling table to satisfy their real-time constraints.

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PROFIBUS에서 대역폭 할당 기법 구현

  • 김지용;홍승호
    • 제어로봇시스템학회:학술대회논문집
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    • pp.97-100
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    • 1997
  • Fieldbuses are used as the lowest level communication network for real-time communication in factory automation and process control systems. Data generated from field devices can be divided into three categories: sporadic real-time, periodic real-time and non real-time data. Since these data share one fieldbus network medium, it needs a method that allocate the limited bandwidth of fieldbus network to the sporadic real-time, periodic real-time and non real-time traffic. This paper introduces an implementation method of bandwidth allocation scheme introduced in [51 on PROFIBUS. Using the modified PROFIBUS FDL(Fieldbus Data Link layer), the bandwidth allocation scheme introduced in [51 is verified by the experiments.

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A Modified DCF Protocol for Real-Time Multimedia Data (Real-Time MultiMedia Data 전송을 위한 새로운 방식의 DCF 프로토콜)

  • 신세영;심승섭;조경익;윤석진
    • Proceedings of the IEEK Conference
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    • pp.157-163
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    • 2003
  • IEEE 802.11a Distributed Coordination Function(DCF) Protocol을 사용하여 Real-Time MultiMedia Data의 전송을 수행할 경우, DCF Protocol의 적합하지 못한 Mechanism에 의하여, Data 전송의 극대화를 이루지 못한다. Retransmission이 반복되는 경우, Binary Slotted Exponential Backoff Mechanism은 거대한 Packet Delay와 Jitter의 원인이 되며 Automatic Repeat Request(ARQ) 방식의 Ack Mechanism은 MultiMedia Data를 전송하기에 적합하지 못하다. 본 논문은 위와 같은 문제점을 해결하기 위하여 Real-Time MultiMedia Data을 주로 전송하는 STA에 따른 Real-Time/Non-Real-Time(RT/NRT) Station(STA)의 구분과 보내고자 하는 Real-Time MultiMedia Data의 Network Traffic Load(The Required Bandwidth)를 고려하여, Modified DCF(mDCF) Protocol의 Modified Backoff(mBackOff), Modified BlockAck(mBlockAck) Mechanism을 제시함으로서, Data 전송의 극대화를 제공하며, 또한 IEEE 802.11a와의 호환성을 제공한다.

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Design of an effective real-time data acquisition system (효율적인 실시간 데이터 수집시스템의 설계)

  • 김동욱;염재명;김대원;박용식
    • 제어로봇시스템학회:학술대회논문집
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    • pp.1036-1039
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    • 1996
  • The performance of real-time systems depends upon how well the tasks are scheduled within a cycle time and how fastly the response is made according to the occurrence of an external event. This paper presents the design of an effective real-time data acquisition system in order to gather the data from an automobile engine. This paper investigates an estimation and a restriction method of execution for aperiodic data. Also, the guarantee problem of real-time constraint is presented for periodic data. Through the experiments, the hard real-time guarantee problem of periodic data is studied and the damage problem of periodic data according to the increase of aperiodic tasks is analyzed.

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Real-Time Transmission Method of Wireless Control Network using IEEE 802.15.4 Protocol (IEEE 802.15.4 기반의 무선 제어 망을 위한 실시간 전송기법에 대한 연구)

  • Lee, Jung-Il;Chol, Dong-Hyuck;Kim, Dong-Sung
    • Proceedings of the KIEE Conference
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    • pp.178-180
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    • 2007
  • In this paper, a real-time transmission algorithm based on IEEE 802.15.4 is proposed. The superframe of IEEE 802.15.4 is applied to the transmission method of real-time mixed data (periodic data, sporadic data, and non real-time message). The simulation results show the real-time performance of sporadic data is improved by using the proposed transmission algorithm.

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Squall: A Real-time Big Data Processing Framework based on TMO Model for Real-time Events and Micro-batch Processing (Squall: 실시간 이벤트와 마이크로-배치의 동시 처리 지원을 위한 TMO 모델 기반의 실시간 빅데이터 처리 프레임워크)

  • Son, Jae Gi;Kim, Jung Guk
    • Journal of KIISE
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    • v.44 no.1
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    • pp.84-94
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    • 2017
  • Recently, the importance of velocity, one of the characteristics of big data (5V: Volume, Variety, Velocity, Veracity, and Value), has been emphasized in the data processing, which has led to several studies on the real-time stream processing, a technology for quick and accurate processing and analyses of big data. In this paper, we propose a Squall framework using Time-triggered Message-triggered Object (TMO) technology, a model that is widely used for processing real-time big data. Moreover, we provide a description of Squall framework and its operations under a single node. TMO is an object model that supports the non-regular real-time processing method for certain conditions as well as regular periodic processing for certain amount of time. A Squall framework can support the real-time event stream of big data and micro-batch processing with outstanding performances, as compared to Apache storm and Spark Streaming. However, additional development for processing real-time stream under multiple nodes that is common under most frameworks is needed. In conclusion, the advantages of a TMO model can overcome the drawbacks of Apache storm or Spark Streaming in the processing of real-time big data. The TMO model has potential as a useful model in real-time big data processing.

Management and control of fieldbus network traffic by bandwidth allocation scheme (대역폭 할당 기법에 의한 필드버스 네트워크의 트래픽 관리 및 제어)

  • Hong, Seung-Ho
    • Journal of Institute of Control, Robotics and Systems
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    • v.3 no.1
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    • pp.77-88
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    • 1997
  • Fieldbus is the lowest level communication network in factory automation and process control systems. Performance of factory automation and process control systems is directly affected by the data delay induced by network traffic. Data generated from several distributed field devices can be largely divided into three categories: sporadic real-time, periodic real-time and non real-time data. Since these data share one fieldbus network medium, the limited bandwidth of a fieldbus network must be appropriately allocated to the sporadic real-time, periodic real-time and non real-time traffic. This paper introduces a new fieldbus design scheme which allocates the limited bandwidth of fieldbus network to several different kinds of traffic. The design scheme introduced in this study not only satisfies the performance requirements of application systems interconnected into the fieldbus but also fully utilizes the network resources. The design scheme introduced in this study can be applicable to cyclic service protocols operated under single-service discipline. The bandwidth allocation scheme introduced in this study is verified using a discrete-event/continuous-time simulation experiment.

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Real-Time Sink Node Architecture for a Service Robot Based on Active Healthcare/Living-support USN (능동 건강/생활지원 USN 기반 서비스 로봇 시스템의 실시간 싱크 노드 구조)

  • Shin, Dong-Gwan;Yi, Soo-Yeong;Choi, Byoung-Wook
    • Journal of Institute of Control, Robotics and Systems
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    • v.14 no.7
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    • pp.720-725
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    • 2008
  • This paper proposes a system architecture for USN with a service robot to provide more active assisted living services for elderly persons by monitoring their mental and physical well-being with USN environments at home, hospital, or silver town. Sensors embedded in USN are used to detect preventive measures for chronic disease. Logged data are transferred to main controller of a service robot via wireless channel in which the analysis of data is performed. For the purpose of handling emergency situations, it needs real-time processing on gathering variety sensor data, routing algorithms for sensor nodes to a moving sink node and processing of logged data. This paper realized multi-hop sensor network to detect user movements with biometric data transmission and performed algorithms on Xenomai, a real-time embedded Linux. To leverage active sensing, a mobile robot is used of which task was implemented with a priority to process urgent data came from the sink-node. This software architecture is anticipated to integrate sensing, communication and computing with real-time manner. In order to verify the usefulness of a proposed system, the performance of data transferring and processing on a real-time OS with non real-time OS is also evaluated.