• 한국컴퓨터산업학회논문지
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• 제2권9호
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• pp.1225-1232
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• 2001

본 논문에서는 광역 ATM 망에서 인터넷 서비스를 제공하기 위하여 입력 소스 트래픽의 QoS 등급에 기초한 라우터 시스템에 적용되는 다양한 스케줄링 알고리즘들을 분석하고 서비스 특성에 따라 QoS 요구사항을 보장할 수 있는 새로운 스케줄링 알고리즘을 제안한다. 이를 위하여, 인터넷망에서의 패킷 다중화기의 요구사항을 살펴보고 실시간 서비스제공을 위한 패킷 다중화기의 기능 구조와, 다양한 QoS를 만족시키기 위한 스케줄링 알고리즘을 설계한다. 마지막으로 모의 실험을 통해 평균 지연 시간 및 망 자원 활용의 공평성 측면에서 알고리즘의 성능을 고찰한다.

• 한국경영과학회지
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• 제32권3호
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• pp.1-15
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• 2007

In this paper, the return link of interactive GEO satellite network providing multimedia services is considered. First, we classify data by delay characteristics, and analyze the numbers of expected lost packets and expected delay packets for each data class of each terminal. Next we mathematically formulate optimal rate scheduling model to minimize the weighted sum of the numbers of expected lost packets and expected delay packets considering priority of each data class. We also suggest a dynamic rate scheduling scheme based on Lagrangean relaxation technique and subgradient technique to solve the proposed model in a fast time. Extensive experiments show that the proposed scheme provides encouraging results.

• International Journal of Computer Science & Network Security
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• 제22권8호
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• pp.45-54
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• 2022

In this study, a multi-objective robust job-shop scheduling (JSS) model was developed. The model considered multi-jobs and multi-machines. The model also considered uncertain processing times for all tasks. Each job was assigned a specific due date and a tardiness penalty to be paid if the job was not delivered on time. If any job was completed early, holding expenses would be assigned. In addition, the model added idling penalties to accommodate the idling of machines while waiting for jobs. The problem assigned was to determine the optimal start times for each task that would minimize the expected penalties. A numerical problem was solved to minimize both the makespan and the total penalties, and a comparison was made between the results. Analysis of the results produced a prescription for optimizing penalties that is important to be accounted for in conjunction with uncertainties in the job-shop scheduling problem (JSSP).

• 한국정보통신학회논문지
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• 제4권5호
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• pp.1037-1050
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• 2000

오늘날의 통신서비스들은 음성이나 데이터 서비스와 같은 전통적인 서비스뿐만 아니라 비디오 서비스와 같은 대량의 데이터를 전송해야만 하는 멀티미디어 서비스를 포함한다. 이러한 요구를 수용하기 위해서 BISDN(Broadband Integated Services Digital Network)이 개발되었고 이의 기반 기술로 ATM이 채택되었다. 다양한 멀티미디어 응용들 중에서 VOD(Video On Demand), 화상회의등은 데이터를 동시에 여러 목적지로 보내는 멀티캐스트 특성이 있다. 그러므로 멀티캐스트 능력은 멀티미디어 통신에서 매우 중요하다. 본 논문에서는 링망을 이용한 병렬 멀티캐스트 패킷스위치(Parallel Multicast Packet Switch with Ring Network: PMRN)에서의 분리된 HOL을 이용한 멀티캐스트 셀 스케줄링 기법을 제안한다. 이 기법은 입력버퍼의 앞단 에 멀티캐스트 셀과 유니캐스트 셀을 위한 분리된 HOL을 두고 non-FIFO방식을 사용함으로서 입력버퍼 내에서 전송 가능한 멀티캐스트 셀과 유니캐스트 셀을 동시에 스케줄링할 수 있도록 하여 입력버퍼 내에서의 지연을 감소시키고 링망과 일대일 연결 네트워크의 이용율을 높이며 스위치의 처리율을 높일 수 있다.

• 전기학회논문지
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• 제56권12호
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• pp.2262-2264
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• 2007

In this paper, we propose a distributed opportunistic scheduling scheme for wireless LAN network. Proportional fair scheduling is one of the opportunistic scheduling schemes and used for centralized networks, whereas we design distributed proportional fair scheduling (DPFS). In the proposed DPFS scheme, each receiver estimates channel condition and calculates independently its own priority with probabilistic manner, which can reduce excessive probing overhead required to gather the channel conditions of all receivers. We evaluate the proposed DPFS using extensive simulation and simulation results show that DPFS obtains up to 23% higher throughput than conventional scheduling schemes and has a flexibility to control the fairness and throughput by controlling the system parameter.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.60.3-60
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• 2001

Usually the static scheduling algorithms such as DMS(Deadline Monotonic Scheduling) or RMS(Rate Monotonic Scheduling) are used for CAN scheduling due to its ease with implementation. However, due to their inherently low utilization of network media, some dynamic scheduling approaches have been studied to enhance the utilization. In case of dynamic scheduling algorithms, two considerations are needed. The one is a priority inversion due to rough deadline encoding into stricted arbitration fields of CAN. The other is an arbitration delay due to the non-preemptive feature of CAN. In this paper, an extended algorithm is proposed from an existing EDS(Earliest Deadline Scheduling) approach of CAN scheduling algorithm having a solution to the priority inverstion ....

• 한국통신학회논문지
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• 제30권9A호
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• pp.762-771
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• 2005

In this paper, an efficient Adaptive quality-of-service (QoS) traffic control scheme with priority scheduling is proposed for the multimedia traffic transmission over wireless access networks. The objective of the proposed adaptive QoS control (AQC) scheme is to realize end-to-end QoS, to be scalable without the excess signaling process, and to adapt dynamically to the network traffic state according to traffic flow characteristics. Here, the reservation scheme can be used over the wireless access network in order to get the per-flow guarantees necessary for implementation of some kinds of multimedia applications. The AQC model is based on both differentiated service model with different lier hop behaviors and priority scheduling one. It consists of several various routers, access points, and bandwidth broker and adopts the IEEE 802.1 le wireless radio technique for wireless access interface. The AQC scheme includes queue management and packet scheduler to transmit class-based packets with different per hop behaviors (PHBs). Simulation results demonstrate effectiveness of the proposed AQC scheme.

• 전자공학회논문지CI
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• 제37권4호
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• pp.26-36
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• 2000

본 논문은 실시간 멀티프로세서 스케줄링 문제를 효과적으로 해결하는 신경망 알고리즘을 제안한다. 제안된 알고리즘은 대표적인 신경망 모델인 홉 필드 네트워크를 근간으로 태스크의 처리요구에 대해 지정된 시간이내에 처리할 수 있는 실시간 시스템을 신경망의 장점인 병렬처리가 가능하도록 구현하였다. 본 알고리즘의 성능을 비교하기 위하여 기존에 실시간 멀티프로세서 스케줄링을 위해 연구되는 EDA와 LLA의 두 알고리즘과 비교한다. 제안된 알고리즘은 VHDL을 이용하여 하드웨어로 설계한다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 추계학술대회 논문집
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• pp.717-720
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• 2000

Event-driven communication protocols such as CAN(Controller Area Network) have inherent packet delays due to the contention process for the use of network medium. These delays are stochastic in nature because most packets arrive at random time instants. The stochastic property of the delay adversely influences the control system's performance in terms of stability, responsiveness and steady-state error. Another problem for safety-critical application such as brake-by-wire systems is the reliability of the communication modules that can fail abruptly. This paper deals with two methods to overcome the above problems : (i) scheduling method that can maintain packet delays under some acceptable level, and (ii) redundancy management of communication modules that prescribes dual-redundancy modules' behavior when one of them fails.

• Journal of Communications and Networks
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• 제18권6호
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• pp.884-891
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• 2016

The wireless mesh network (WMN) has attracted significant interests as a broadband wireless network to provide ubiquitous wireless access for broadband services. Especially with incorporating multiple orthogonal channels and multiple directional antennas into the WMN, each node can communicate with its neighbor nodes simultaneously without interference between them. However, as we allow more freedom, we need a more sophisticated algorithm to fully utilize it and developing such an algorithm is not easy in general. In this paper, we study a joint channel assignment, link scheduling, routing, and rate control problem for the WMN with multiple orthogonal channels and multiple directional antennas. This problem is inherently hard to solve, since the problem is formulated as a mixed integer nonlinear problem (MINLP). However, despite of its inherent difficulty, we develop an algorithm to solve the problem by using the generalized Benders decomposition approach [2]. The simulation results show the proposed algorithm provides the optimal solution to maximize the network utility, which is defined as the sum of utilities of all sessions.