• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권4호
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• pp.1324-1343
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• 2014

In recent years, the problem of spectrum mobility in Cognitive Radio (CR) Networks has been widely investigated. In order to utilize spectrum resources completely, many spectrum handoff techniques based on game theory have been proposed, but most studies only concern that users how to achieve better payoffs, without much attention to the diverse needs of users. In this paper, we propose a new channel-switching model based on game theory, using a prioritized approach to meet the diverse needs of users in two different modes (CQ and PS). At the same time, this paper proposes some acceleration techniques to reach the Nash equilibrium more efficiently. We evaluate the performance of the proposed schemes depending on priority using real channel availability measurements, and conclude that the channel quality function (CQ) mode provide better service for priority user but the plan-sorting (PS) mode can be more suitable in multiple priority users exist scene.

• 산업경영시스템학회지
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• 제35권4호
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• pp.162-170
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• 2012

We propose a new priority discipline called the strict T-preemptive priority discipline, and derive the waiting time distributions of each class in the strict T-preemptive priority M/G/1 queue. Using this queueing analysis, we evaluate the performance of an opportunistic spectrum access in cognitive radio networks, where a communication channel is divided into time slots, a licensed primary user is assigned to one channel, and multiple unlicensed secondary users may opportunistically exploit time slots unused by the primary user. We also present a numerical example of the analysis of the opportunistic spectrum access where the arrival rates and service times distributions of each users are identical.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -3
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• pp.1831-1834
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• 2002

In this paper, we present results of a study of congestion control for real-time communication based on ATM networks. In ATM networks, congestion usually results in cell loss. Based on the time limit and priority, the cells that compete for the same output line could be lined according to the character of real-time service. We adopt priority control algorithm for providing different QoS bearer services that can be implemented by using threshold methods at the ATM switching nodes, the cells of different deadline and priority could be deal with according to the necessity. Experiments show the proposed algorithm is effective in the congestion control of ATM real-time networks

• 인터넷정보학회논문지
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• 제18권6호
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• pp.65-73
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• 2017

Congestion occurring at wireless sensor networks(WSNs) causes packet delay and packet drop, which directly affects overall QoS(Quality of Service) parameters of network. Network congestion is critical when important data is to be transmitted through network. Thus, it is significantly important to effectively control the congestion. In this paper, new mechanism to guarantee reliable transmission for the important data is proposed by considering the importance of packet, configuring packet priority and utilizing the settings in routing process. Using this mechanism, network condition can be maintained without congestion in a way of making packet routed through various routes. Additionally, congestion control using packet service time, packet inter-arrival time and buffer utilization enables to reduce packet delay and prevent packet drop. Performance for the proposed mechanism was evaluated by simulation. The simulation results indicate that the proposed mechanism results to reduction of packet delay and produces positive influence in terms of packet loss rate and network lifetime. It implies that the proposed mechanism contributes to maintaining the network condition to be efficient.

• 한국통신학회논문지
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• 제19권2호
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• pp.381-389
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• 1994

고품질 음성, 고속의 데이터 및 영상 등과 같은 멀티미디어 서비스는 통신망에서 기존에 제공하는 서비스에 부가될 것이다. 이와같은 서비스는 통신망에 대해서 새로운 요구를 발생시킨다. 우선순위 제어 메카니즘은 많은 통신 시스템에서 발생된 멀티미디어 서비스를 제어하는데 사용될 수 있다. 우선순위 메카니즘은 서비스 품질에 따라 발생된 정보에 우선순위를 부여하는 트래픽 제어 방식중의 하나로서 우선순위의 할당은 손실 민감도와 지연 민감도등과 같은 트래픽 특성에 대한 우선순위 기준에 의해서 나누어질 수 있다. 본 논문에서는 손실을 줄이는 트래픽 제어로서 부분버퍼 공유(PBS:Partial Buffer Sharing)방식을 이용하고 Markov Chain을 이용한 해석 방법을 제안한다. 제안한 해석 방법을 검증하기 위해서 시뮬레이션 전용 언어인 SIMSCRIPT 11.5를 이용해서 시뮬레이션을 수행하였다. 시뮬레이션 결과 제안한 해석방법이 타당함을 검증하였다. 또한 ATM 망에 결과를 적용했을때 ATM 망의 셀(CELL) 손실 확률을 구하였다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국내학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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• pp.1000-1005
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• 1993

In this paper asymptotic formulate for performance characteristics throughput, delay) of large scale token-passing networks with priorities and limited service are given. In particular, adaptive control procedures for obtaining optimal buffer capacity with respect to each priority and optimal limited service are shown. All results obtained are supported by simulations.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제7권1호
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• pp.15-23
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• 2003

ATM networks provide the various kinds of service which require the different Quality of Services(QoS) such as loss and delay. By statistically multiplexing of traffics and the uncertainty and fluctuation of source traffic pattern, the congestion may occur. The leaky bucket scheme is a representative policing mechanism for preventive congestion control. In this paper, we analyze the HOL(Head-of-Line) priority leaky bucket scheme. That is, traffics are classified into real-time and nonreal-time traffic. The real-time traffic has priority over nonreal-time traffic for transmission. For proposed mechanism, we obtain the system state distribution, finally the loss probability and the mean waiting time of real-time and nonreal-time traffic. The simple numerical examples also are presented.

• Journal of Communications and Networks
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• 제13권2호
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• pp.132-141
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• 2011

IEEE 802.15.4 networks are a feasible platform candidate for connecting all health-care-related equipment dispersed across a hospital room to collect critical time-sensitive data about patient health state, such as the heart rate and blood pressure. To meet the quality of service requirements of health-care systems, this paper proposes a multi-priority queue system that differentiates between various types of frames. The effect of the proposed system on the average delay and throughput is explored herein. By employing different contention window parameters, as in IEEE 802.11e, this multi-queue system prioritizes frames on the basis of priority classes. Performance under both saturated and unsaturated traffic conditions was evaluated using a novel analytical model that comprehensively integrates two legacy models for 802.15.4 and 802.11e. To improve the accuracy, our model also accommodates the transmission retries and deferment algorithms that significantly affect the performance of IEEE 802.15.4. The multi-queue scheme is predicted to separate the average delay and throughput of two different classes by up to 48.4% and 46%, respectively, without wasting bandwidth. These outcomes imply that the multi-queue system should be employed in health-care systems for prompt allocation of synchronous channels and faster delivery of urgent information. The simulation results validate these model's predictions with a maximum deviation of 7.6%.

• 대한전자공학회논문지SD
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• 제44권10호
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• pp.55-60
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• 2007

본 논문에서는 QoS를 보장하면서 빠른 네트워크 속도를 지원해 줄 수 있는 우선순위 큐의 구조를 제안한다. 제안한 큐의 구조는 하나의 큐로 여러 개의 출력부에 출력을 보낼 수 있어 면적을 줄일 수 있고, 제어 블록을 추가함으로써 기존의 multiple systolic way 우선순위 큐보다 더 빠른 속도로 동작할 수 있기 때문에 높은 패킷 처리 속도를 요구하는 패킷 스케줄러 등에 적합한 구조이다. 또한, 이 구조는 높은 확장성을 지원한다.

• ETRI Journal
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• 제40권3호
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• pp.347-354
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• 2018

Using various offset times to separate differential services is the most common form of service differentiation in optical burst switching networks. In this approach, a larger offset time is given to a higher priority burst, but it causes this burst to have a longer delay. One solution to this problem is to adjust the burst assembly time so that the buffering delay of the higher priority burst is always shorter than that of the lower priority burst. However, this adjustment causes another problem, called delay unfairness, for bursts with differential priorities that share the same path to their destination. This article proposes a new solution for delay fairness using the burst assembly.