• Proceedings of the Korean Information Science Society Conference
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• 2000.10c
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• pp.473-475
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• 2000

무선 네트워크의 급격한 성장으로 기존의 전자우편, 멀티미디어 등의 응용을 이동 컴퓨팅 환경에서 보다 효과적으로 지원해야 할 필요성이 증대되었다. 기존 유선 네트워크 환경에서 사용자의 독립적 서비스 보장과 요구 비율에 따른 자원의 공정한 배분을 위해서 Fair Queueing 기법이 제안되었다. 이 Fair Queueing 기법을 무선 네트워크에 적용하려는 연구가 진행되고 있으나 무선 미디어 자원의 빈약성과 사용자 이동에 따른 오류 발생 가능성 등으로 인해 아직까지 체계적인 기술은 미비한 형편이다. 본 논문에서는 기존 Fair Queueing 기법에서 각 세션의 가중치를 조절하여 무선 네트워크 환경에서 사용자의 다양한 서비스 품질(QoS; Queueing of Service)을 지원하고 오류 발생시 급격한 서비스 품질 저하를 방지하는 패킷 서비스 기법을 제시하고 그 성능을 분석한다.

• Journal of Communications and Networks
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• v.7 no.1
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• pp.87-92
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• 2005

This paper presents basic queueing analysis contributing to teletraffc theory, with commonly accessible mathematical tools. This paper studies queueing systems with bulk arrivals. It is assumed that the number of arrivals and the expected number of arrivals in each bulk are bounded by some constraints B and (equation omitted), respectively. Subject to these constraints, convexity argument is used to show that the bulk-size probability distribution that results in the worst mean queue performance is an extremal distribution with support {1, B} and mean equal to A. Furthermore, from the viewpoint of security against denial-of-service attacks, this distribution remains the worst even if an adversary were allowed to choose the bulk-size distribution at each arrival instant as a function of past queue lengths; that is, the adversary can produce as bad queueing performance with an open-loop strategy as with any closed-loop strategy. These results are proven for an arbitrary arrival process with bulk arrivals and a general service model.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.4C
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• pp.343-355
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• 2003

Fair bandwidth allocations at routers protect adaptive flows from non-adaptive ones and may simplify end-to end congestion control. However, traditional fair bandwidth allocation mechanisms, like Weighted Fair Queueing and Flow Random Early Drop, maintain state, manage buffera and perform packet scheduling on a per-flow basis. These mechanisms are more complex and less scalable than simple FIFO queueing when they are used in the interi or of a high-speed network. Recently, to overcome the implementation complexity problem and address the scalability and robustness, several fair bandwidth allocation mechanisms without per-flow state in the interior routers are proposed. Core-Stateless Fair Queueing and Rainbow Fair Queuing are approximates fair queueing in the core-stateless networks. In this paper, we proposed simple Layered Fair Queueing (SLFQ), another core-stateless mechanism to approximate fair bandwidth allocation without per-flow state. SLFQ use simple layered scheme for packet labeling and has simpler packet dropping algorithm than other core-stateless fair bandwidth allocation mechanisms. We presente simulations and evaluated the performance of SLFQ in comparison to other schemes. We also discussed other are as to which SLFQ is applicable.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1994.04a
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• pp.514-514
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• 1994

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1996.04a
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• pp.548-548
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• 1996

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1988.10a
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• pp.14-14
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• 1988

• Journal of applied mathematics & informatics
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• v.8 no.3
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• pp.1035-1045
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• 2001

We present two decomposition approximations for the mean sojourn times in open single class queing networks. If there is a single bottleneck station, the approximations are asymptotically exact in both light and heavy traffic. When applied to a Jackson network or an M/G/1 queue, these approximations are exact for all values of the traffic intensity.

• Journal of the Korean Operations Research and Management Science Society
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• v.14 no.2
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• pp.87-96
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• 1989

We develop an algorithm to determine the optimal loading policy, which minimizes the congestion in general queueing networks with variable stations. Under more specified condition, majorization and arrangement ordering are established to compare, respectivity, various loading and assignment policies. Implications of results are also discussed.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.28 no.1
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• pp.114-120
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• 2005

This paper studies procedures for bottleneck detection in closed queueing networks(CQN's) with multiple job classes. Bottlenecks refer to servers operating at $100\%$ utilization. For CQN's, this can occur as the population sizes approach infinity. Bottleneck detection reduces to a non-linear complementary problem which in important special cases may be interpreted as a Kuhn-Tucker set. Efficient computational procedures are provided.

• Journal of Korean Institute of Industrial Engineers
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• v.21 no.2
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• pp.289-298
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• 1995

We consider a general queueing network with multi-server stations. The stations are under heavy traffics or moderate variable conditions. We develope an algorithm to determine the optimal loading policy, which minimizes the congestion in a network. Under more specified condition, majorization and arrangement orderings are established to compare, respectively, various loading and assignment policies. Implications of results are also discussed.