• Title/Summary/Keyword: Load control protocol

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Performance analysis and comparison of distributed wireless media access control protocols (분산 무선 매체접근제어 프로토콜의 성능 분석 및 비교)

  • 김재현;이종규
    • Journal of the Korean Institute of Telematics and Electronics S
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    • v.34S no.9
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    • pp.1-12
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    • 1997
  • The performance of Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA) protocol adopted as a draft standard of IEEE 802.11 wireless LAN, is analyzed by using mathematical method based on renewal theory. We introdude three kinds of CSMA/CA protocols basic, stop-and-wait and 4-Way handshake CSMA/CA with their mathematical analysis. First, a network of finite population is considered and then expand to infinite population. We model the CSMA/CA protocol as a hybrid protocol of 1-persistent CSMA and p-persistent CSMA protocol, and verify analaytical results by computer simulation. We have found that 4-Way Handshake CAMA/CA shows better performance than those of other two types of CSMA/CA in case of high traffic load.

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A Distributed Conference Architecture with a New Load Control Method (새로운 부하 제어 방식을 사용한 분산형 컨퍼런스 구조)

  • Jang, Choon-Seo
    • Journal of the Korea Society of Computer and Information
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    • v.17 no.6
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    • pp.67-73
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    • 2012
  • A distributed conference architecture with a new load control method has been suggested in this paper. A new event package in this paper enables to control conference load. Some additional elements for exchanging SIP messages between server and participants, and for distributing the load, have been added to new conference information data format. Furthermore to lessen the load, all conference servers share the processing of conference information data which should be transferred periodically to all participants. The suggested load control event package makes each server can get current load status of the overall servers. When load increases in one server SIP client requests are distributed by selecting a server which has the lowest load value, or new server is created to share the load. The performance of the proposed system has been evaluated by experiments. They shows 21.6% increase in average delay time, and 29.2% increase in average SIP message processing time.

A New XMPP/SIP Presence Service System by Multiple Servers Architecture (다중 서버 구조에 의한 새로운 XMPP/SIP 프레즌스 서비스 시스템)

  • Lee, Ky-Soo;Jang, Choonseo
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.19 no.5
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    • pp.1144-1150
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    • 2015
  • Presence information provides various informations about users such as on-line status, current location, network connection method and connection address, and there are two kinds of presence information, SIP(Session Initiation Protocol) based presence information and XMPP(Extensible Massaging and Presence Protocol) based presence information. In this paper, a multiple server architecture that can handle these two kinds of presence information has been proposed. In this architecture, severs are added dynamically according to number of users to provide system scalability, and load of each server can be effectively controlled. In this system, a new XMPP stanza architecture and presence information data format are designed for load control. Furthermore message exchanging procedures between servers and users for dynamic server control has been also suggested. The performance of the proposed system has been analysed by simulation.

Dynamic Clustering for Load-Balancing Routing In Wireless Mesh Network

  • Thai, Pham Ngoc;Hwang, Min-Tae;Hwang, Won-Joo
    • Journal of Korea Multimedia Society
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    • v.10 no.12
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    • pp.1645-1654
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    • 2007
  • In this paper, we study the problem of load balancing routing in clustered-based wireless mesh network in order to enhance the overall network throughput. We first address the problems of cluster allocation in wireless mesh network to achieve load-balancing state. Due to the complexity of the problem, we proposed a simplified algorithm using gradient load-balancing model. This method searches for a localized optimal solution of cluster allocation instead of solving the optimal solution for overall network. To support for load-balancing algorithm and reduce complexity of topology control, we also introduce limited broadcasting between two clusters. This mechanism maintain shortest path between two nodes in adjacent clusters while minimizing the topology broadcasting complexity. The simulation experiments demonstrate that our proposed model achieve performance improvement in terms of network throughput in comparison with other clustering methods.

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XMPP/SIP Presence Service System using Efficient Message Control Method (효율적 메시지 제어방식을 사용한 XMPP/SIP 프레즌스 서비스 시스템)

  • Jang, Choonseo
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.18 no.11
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    • pp.2678-2684
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    • 2014
  • In this paper a new message control method that can reduce server load and network traffic in XMPP/SIP presence service system has been proposed. This presence service system can process both XMPP(Extensible Massaging and Presence Protocol) based presence information and SIP(Session Initiation Protocol) based presence information. A new XMPP stanza architecture with added elements for presence stanza and IQ stanza has been designed, and a new presence information data processing method which can reduce size of SIP notification message and SIP PUBLISH message has been suggested. Furthermore a messages exchanging procedure that can transfer presence information between XMPP domain and SIP domain has been also suggested. The performance of the proposed system has been analysed by simulation.

A MULTIPATH CONGESTION CONTROL SCHEME FOR HIGH-QUALITY MULTIMEDIA STREAMING

  • Lee, Sunghee;Chung, Kwangsue
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.11 no.1
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    • pp.414-435
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    • 2017
  • As network adaptive streaming technology becomes increasingly common, transport protocol also becomes important in guaranteeing the quality of multimedia streaming. At the same time, because of the appearance of high-quality video such as Ultra High Definition (UHD), preventing buffering as well as preserving high quality while deploying a streaming service becomes important. The Internet Engineering Task Force recently published Multipath TCP (MPTCP). MPTCP improves the maximum transmission rate by simultaneously transmitting data over different paths with multiple TCP subflows. However, MPTCP cannot preserve high quality, because the MPTCP subflows slowly increase the transmission rate, and upon detecting a packet loss, drastically halve the transmission rate. In this paper, we propose a new multipath congestion control scheme for high-quality multimedia streaming. The proposed scheme preserves high quality of video by adaptively adjusting the increasing parameter of subflows according to the network status. The proposed scheme also increases network efficiency by providing load balancing and stability, and by supporting fairness with single-flow congestion control schemes.

MPMTP-AR: Multipath Message Transport Protocol Based on Application-Level Relay

  • Liu, Shaowei;Lei, Weimin;Zhang, Wei;Song, Xiaoshi
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.11 no.3
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    • pp.1406-1424
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    • 2017
  • Recent advancements in network infrastructures provide increased opportunities to support data delivery over multiple paths. Compared with multi-homing scenario, overlay network is regarded as an effective way to construct multiple paths between end devices without any change on the underlying network. Exploiting multipath characteristics has been explored for TCP with multi-homing device, but the corresponding exploration with overlay network has not been studied in detail yet. Motivated by improving quality of experience (QoE) for reliable data delivery, we propose a multipath message transport protocol based on application level relay (MPMTP-AR). MPMTP-AR proposes mechanisms and algorithms to support basic operations of multipath transmission. Dynamic feedback provides a foundation to distribute reasonable load to each path. Common source decrease (CSD) takes the load weight of the path with congestion into consideration to adjust congestion window. MPMTP-AR uses two-level sending buffer to ensure independence between paths and utilizes two-level receiving buffer to improve queuing performance. Finally, the MPMTP-AR is implemented on the Linux platform and evaluated by comprehensive experiments.

Performance Analysis of An Optimal Access Control Protocol (고속 통신을 위한 최적 액세스제어 프로토콜의 성능 분석)

  • 강문식;이상헌;이상배
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.19 no.10
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    • pp.1945-1956
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    • 1994
  • In this paper, a multiaccess network protocol for high-speed communication is proposed, which enables multimedia sevices with integrating the existing networks. We examine the traffic control mechanisms and configurations for the network architecture and compare with various protocols which are suitable to high speed LAN/MAN and propose an adaptive access control mechanism. ATMR has low channel utilization due to window size reset time, and that MetaRing is very sensitive over the change of traffic load. This suggested protocol, however, has quite a good performance for that situation by adding adaptive parameter condition. This mechanism may introduce a model of small-scaled Broadband Integrated Service Network and be used as an internetworking system for the ATM network.

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Implementation of a Fieldbus System Based on Profibus-DP Protocol (Profibus-DP 프로토콜을 이용한 필드버스 시스템 구현)

  • Bae, Gyu-Sung;Kim, Jong-Bae;Park, Byoung-Wook;Lim, Kye-Young
    • Journal of Institute of Control, Robotics and Systems
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    • v.6 no.10
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    • pp.903-910
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    • 2000
  • In this paper, we describe a slave chip based on the Profibus-DP protocol and a system board to verify the developed slave chip. The Profibus-DP protocol is designed using VHDL and implemented on FPGA. The system board adopting the developed FPGA is designed FPGA is designed in which the firmware is implemented on Intel 8051 by using C language. Among the Profibus-DP protocols, low level layers from the physical layer to the data link layer is implemented in the form of hardware that we are able to greatly reduce the CPU load in processing protocols, and then higher layers could be processed by software. These technologies result in an IP to make terminal devices in the distributed control systems. Therefore, many digital logics as well as communication logics can be implemented onto SOC(System On a Chip) and it could be applied to various fieldbus-related areas.

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Exploring the Effect of Mental Demand in Web Searches: A Pilot Study

  • Na, Kyoungsik
    • Journal of the Korean Society for Library and Information Science
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    • v.48 no.2
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    • pp.379-398
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    • 2014
  • This pilot study explored the effect of mental demand on a Web searcher's thoughts, emotions, efforts, and performance in Web searches in order to address whether or not there is any difference between searchers exposed to mental demand manipulation and searchers not exposed. Research data were collected via think-aloud protocol (TAP) with a dual-task in experiments and interviews with 10 subjects who participated in this study. For the searcher's thoughts, relevance judgment was found to be hindered by mental demand. For the searcher's emotions, the experimental group was more frustrated than the control group. With respect to the searcher's efforts, searchers for the experimental group with mental demand manipulation were more likely to spend more time, make fewer queries, and visit fewer pages but work harder to find more relevant information that they needed. Lastly, with regard to the searcher's performance, it is likely that performance was highly dependent upon the completion of the search tasks for both groups. The NASA-TLX six components and cognitive load scores of searchers did not make a significant difference in the outcome. The findings support the use of a dual-task methodology as a promising approach for the assessment of cognitive load induced by complex Web searches.