• Title/Summary/Keyword: Two Priority

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Two Priority Class Polling Systems with Batch Poisson Arrivals

  • Ryu, Won;Kim, Dae-Ung;Lee, Bok-Lai;Park, Byeong-U;Chung, Jin-Wook
    • Communications for Statistical Applications and Methods
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    • v.6 no.3
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    • pp.881-892
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    • 1999
  • In this paper we consider a polling system with two classes of stations; high priority and low priority. High priority stations are polled more frequently than low priority stations. We derive an exact and explicit formula for computing the mean waiting times for a message when the arrival processes are batch Poisson. In general the formula requires to solve two sets of simultaneous equations By specializing them to the case of two priority classes we greatly reduce the number equations and provide a simple formula for mean waiting times. We apply the results to a data communication processing system and show that the overall mean waiting time can be reduced by using priority polling.

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STABILITY CONDITION OF DISCRETE-TIME $GEO^x$/G/1 QUEUE WITH PREEMPTIVE REPEAT PRIORITY

  • Lee, Yutae
    • Journal of applied mathematics & informatics
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    • v.12 no.1_2
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    • pp.291-297
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    • 2003
  • This paper considers discrete-time two-class Ge $o^{X/}$G/1 queues with preemptive repeat priority. Service times of messages of each priority class are i.i.d. according to a general discrete distribution function that may differ between two classes. Completion times are derived for the preemptive repeat identical and different priority disciplines. By using the completion time, the stability condition for our system is investigated.d.

ANALYSIS OF QUEUEING MODEL WITH PRIORITY SCHEDULING BY SUPPLEMENTARY VARIABLE METHOD

  • Choi, Doo Il
    • Journal of applied mathematics & informatics
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    • v.31 no.1_2
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    • pp.147-154
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    • 2013
  • We analyze queueing model with priority scheduling by supplementary variable method. Customers are classified into two types (type-1 and type-2 ) according to their characteristics. Customers of each type arrive by independent Poisson processes, and all customers regardless of type have same general service time. The service order of each type is determined by the queue length of type-1 buffer. If the queue length of type-1 customer exceeds a threshold L, the service priority is given to the type-1 customer. Otherwise, the service priority is given to type-2 customer. Method of supplementary variable by remaining service time gives us information for queue length of two buffers. That is, we derive the differential difference equations for our queueing system. We obtain joint probability generating function for two queue lengths and the remaining service time. Also, the mean queue length of each buffer is derived.

An Application of the Cross-impact Hierarchy Process to Evaluate Aeronautics Technologies: A Case Study (상호영향계층분석방법을 이용한 항공기술의 평가에 관한 연구)

  • Kwon, Cheol-Shin;Cho, Keun-Tae
    • Proceedings of the Korean Operations and Management Science Society Conference
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    • 2000.10a
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    • pp.259-262
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    • 2000
  • The Cross-impact Hierarchy Process (CHP), an extended model of the Analytic Hierarchy Process(AHP) which is linked to Cross Impact Analysis(CIA), is a powerful decision making tool to assist in the ranking of large number of dependent technological alternatives. In this paper, we will describe an application of the CHP to the aerospace industry. We here conducted a questionnaire survey for S company that is one of the representative aerospace companies in Korea. A questionnaire was designed to obtain both the priority with dependence (the CHP priority) and the priority with independence (the AHP priority) in order to compare the priority derived by each of two methods. The hierarchy in this case study is concerned with priority setting for R&D area to ensure dependent aerospace design technology of the company, The result shows that there exists the difference hard to neglect between the final priorities gained by two methods.

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A Priority Scheme for IEEE 802.11 Wireless LAN

  • Jang, Yeong-Min
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.25 no.12B
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    • pp.1996-2002
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    • 2000
  • This paper investigates a priority scheme for IEEE 802.11 Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA) protocol in order to provide short access times for priority frames (e.g. time-deadline traffic) even when the overall traffic on the wireless channel is heavy. Under the compatibility constraint for the IEEE 802.11 wireless LANs, two priority systems are simulated: no priority (current IEEE 802.11 standard) for time-deadline traffics and dynamic time-deadline priority. We evaluate algorithms to improve the time-deadline traffic performance using discrete event simulation (DES)

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A Study on PBS Mechanism with Two-Threshold in ATM Networks (ATM망에서 두 개의 임계값을 갖는 PBS 기법에 관한 연구)

  • 정현숙;신효영;박호균;류황빈
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.19 no.1
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    • pp.56-65
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    • 1994
  • As a method to control the congestion, priority mechanism which gives two-level priority to various traffics using CLP bit in cell haeder is carried in ATM network. In this paper, we proposed PBS(partial buffer sharing) mechanism with two threshold for provide three-level priority using CLP bit and Res. bit. By performance analysis proposed mechanism, we knew that provides flexibility to satisfy requirements of various quality of service, compare to existing mechanism with two-level priority.

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A Study on Data Transmission Using Dual Frequency (Dual 주파수를 이용한 Data 전송에 관한 연구)

  • Lee, Jin;Park, Sung Soo
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.31 no.6
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    • pp.398-402
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    • 2018
  • The following conclusions were obtained after analyzing the data transmission characteristics using two frequencies and studying a system that selects data with a good reception frequency as a priority data. Data transmission and reception using two frequencies were measured at -41 to -51 dBm when the frequency was normal, and data transmitted at 900 MHz was selected as priority data. When priority frequency failure occurred, the frequency reception data of the next rank was automatically adopted, and when the frequency of the next rank was disturbed, the priority frequency search was performed again. The above results show that the use of two frequencies enables more stable data transmission and transmission, and further studies should be continued to expand the transmission and reception distances.

Performance Analysis of ATM Switch Using Priority Control by Cell Transfer Ratio (셀 전송비율에 의한 우선순위 제어방식을 사용한 ATM 스위치의 성능 분석)

  • 박원기;김영선;최형진
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.32A no.12
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    • pp.9-24
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    • 1995
  • In this paper, we proposed and analysed two kinds of priority control mechanism to archive the cell loss rate requirement and the delay requirement of each class. The service classes of our concern are the high time priority class(class 1) and the high loss priority class(class 2). Two kinds of priority control mechanism is divided by the method of storing the arriving class 2 cell in buffer on case of buffer full. The first one is the method which discarding the arriving class 2 cell, the second one is the mothod which storing the arriving class 2 cell on behalf of pushing out the class 1 cell in buffer. In the proposed priority schemes, one cell of the class 1 is transmitted whenever the maximum K cells of the class 2 is transmitted on case of transmitting the class 1 cell and the class 2 cell sequentially. In this paper, we analysed the cell loss rate and the mean cell delay for each class of the proposed priority scheme by using the Markov chain. The analytical results show that the characteristic of the mean cell delay becomes better for the class 1 cell and that of the cell loss rate becomes better for the class 2 cell by selecting properly the cell transfer ratio according to the condition of input traffic.

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Aggregation of Multiple Evaluator's Weights in Applying the AHP to Evaluate Technology Alternatives (기술대안의 전략적 평가를 위한 AHP적용에 있어서 평가자 신뢰성을 고려한 가중치 통합)

  • 조근태
    • Korean Management Science Review
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    • v.19 no.2
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    • pp.139-153
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    • 2002
  • The Analytic Hierarchy Process (AHP) is known as a very useful decision-making model developed for obtaining the relative weights of alternatives through pairwise comparison in the context of hierarchical structure. In this paper, we propose a method to reflect the reliability of evaluators in the process of pairwise comparison. This method is applied to the evaluation of aerospace technology alternatives. We have conducted a questionnaire survey for S company that is one of the representative aerospace companies in Korea. A questionnaire was designed for obtaining both the priority with considering the reliability of evaluators' importance weights (the modified AHP priority) and the priority with assuming equally reliable evaluators' importance weights (the AHP priority) in order to compare the priority derived by each of two methods. The result shows that there exists the difference hard to neglect between the final priorities gained by two methods.

A Study on the Queueing with Dynamic Priority in Communication Network (통신망에서의 동적우선도큐잉에 관한 연구)

  • 이재호;송영재
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.12 no.2
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    • pp.92-101
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    • 1987
  • Messages which are entered into communication networks are processed according to the priorities manipulated by serveral queueing disciplines. This study is concerned with one of those disciplines, dynamic priority. We analyzed the everage waiting time for the messages be processed by dynamic priority in queue. The priority is variated by the message's waiting time in queue. The dynamic priority discipline can be classified according as messaged have initial priority or not. Difference of above two discriplines were considered.

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