• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.05a
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• pp.289-293
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• 2011

In our previous research, we proposed a MOST GATEWAY system for organically connected to the network MOST150 and MOST 25 and we proposed a simulation design method for performance analysis of Scheduling Algorithm in MOST GATEWAY system. Therefore in this paper, after comparing the performance among the existing scheduling algorithm methods in MOST25 and MOST150 Networks, we use NS-2 simulator in order to analyze the performance. Finally, we present an improvement scheme of the efficiency and scalability.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.5
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• pp.462-466
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• 2008

This paper proposes a stable gain scheduling method of linear time invariant controllers for tracking servo system. In order to read and write the data on the optical disc, the pick-up head should be moved to the exact track quickly and follow the track immediately. Two different controllers are used for each moving and track-following. In pull-in period, a transition period from moving to track-following, the head might slip and miss the target track. This brings on another searching process and increases the total time. One way to avoid slipping is to extend the bandwidth of the track-following controller. But, extending the bandwidth could degrade the following performance. More prevalent way is to use one more controller in this pull-in period and switch to the following controller. In general, however, switching or scheduling of stable controllers cannot guarantee the stability. This paper suggests an scheduling method guaranteeing the overall stability not only in a generalized form but also in special form for SISO system. The sufficient condition is derived from the fact that Q factor of a stable controller should be stay in $RH_{\infty}$ space. In the experiment, the proposed method shows better performance than the switching method such as shorter time and lower current consumption.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.5
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• pp.783-791
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• 2006

In e-Trade, Real-Time System(RTS) plays a very important role. Each task is set with limited time, and appointed regulations must be followed because it can be greatly damaged if it cannot be executed in limited time. In e-Trade, the scheduling possibility techniques generally use periodical tasks; however, it is necessary to study more stable prediction scheduling possibility algorithm by using other task timing conditions and non-periodical task scheduling tasks. This study proposed an algorithm to increase the prediction possibility using individual task utilization rate, and presented scheduling possibility conditions using existing whole task utilization rate and the proposed algorithm.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.11
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• pp.4419-4435
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• 2015

The use of an efficient packet scheduling scheme for a forward link in satellite communication networks is very important to support fairness for each return channel satellite terminal (RCST) and the service differentiations for user traffics. To support fairness and QoS for each RCST with service-level agreement (SLA), the Adaptive Coding and Modulation (ACM) system in a satellite hub has to process packets with considering modulation and coding (MODCOD) and packet types. Although a DVB-S2 system with ACM scheme has higher transmission efficiency, it cannot offer fairness or quality of service (QoS) to RCSTs. Because the data are transmitted with high MODCOD in regions with clear skies, while data are transmitted using low MODCOD in regions experiencing rain events. In this paper, we propose a two-step scheduling scheme offering fairness and QoS to RCSTs, while minimizing a decrease in throughput. The proposed scheme is carried out performance evaluations using a computer simulation. As results of this simulation, the proposed scheduler was shown to support bandwidth fairness to an individual RCST, and provide a level of QoS differentiation for user traffics.

• Journal of the Korea Society of Computer and Information
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• v.7 no.2
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• pp.1-8
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• 2002

By now, Schedulers for RMS and EDF are implemented for real-time Linux Scheduler. These Schedulers are used for do not consider there's characteristics. Missing Schedulability-test cause result that increase deadline miss rate. Also The present real-time Linux causes system halt Because of scheduling for unschedulable tasks . These appearances are very fatal for real-time system. Therefor, In this paper The peaceful schedulability-test use scheduler which is proper characteristics of RMS and EDF scheduling methods. This scheduler keeps deadline and eliminates system halt from scheduling unschedulable tasks. In this paper, we propose the schedulability-test algorithm and scheduler select algorithm for the effective management of tasks sets.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.10a
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• pp.441-444
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• 2010

In our previous research, we proposed a MOST GATEWAY system for organically connected to the network MOST150 and MOST 25 and a simulation design method for performance analysis of Scheduling Algorithm in MOST GATEWAY system. Therefore in this paper, we use CANoe.MOST simulator in order to analyze the performance and propose a algorithm design method for Performance analysis according to number of queues by applying existing scheduling algorithms. Finally, we present an improvement scheme of the efficiency and scalability.

• The Journal of Engineering Research
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• v.6 no.1
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• pp.5-14
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• 2004

Finding a solution to a constraint satisfaction problem requires choosing values for variables so as to satisfy the constraints of the problem. A constraint is simply a logical relation among several unknowns (or variables), each taking a value in a given domain. Conventional constraint-based scheduling systems are not enough to satisfy the all constraints because there are conflicts between them. In this paper, we propose a method for interactive scheduling, which have two major problems: first, it is hard to satisfy concretely all various kinds of constraints, and second, the search space is extremely large and requires a long execution time. To solve the above problems, we introduce the Interactive Scheduling System (ISS) that interacts with the user to exchange suggestions each other. Our system is performed in two steps: knowledge base generation of an initial assignment and iterative improvement with the user(host or internet client) to satisfy the constraints. Applying our system, we actually constructed timetables for our university, where the scheduling time is considerably reduced.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.1B
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• pp.20-26
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• 2010

The downlink scheduling algorithm has a great impact on the performance of mobile telecommunication system. In proportional fairness (PF) scheduling algorithm, the resource is allocated proportionally to the quality of wireless channel. Thus, PF has difficulty in servicing the users having more downlink traffic. One can allocate the resource proportionally to the accumulated queue length. However, this leads to system throughput degradation since the users having low channel quality get more and more resource allocated due to accumulation property of queue. In this paper, we propose a new downlink scheduling algorithm, which extends PF algorithm by incorporating downlink traffic arrival rate. The proposed algorithm can effectively cope with users having more downlink traffic, and maintain high system throughput by eliminating accumulation effect in the algorithm. With computer simulations, it is verified that the proposed algorithm performs better than existing algorithms.

• The KIPS Transactions:PartA
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• v.16A no.1
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• pp.9-16
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• 2009

Because Grid system consists of heterogenous computing resources, which are distributed on a wide scale, it is impossible to efficiently execute applications with scheduling algorithms of a conventional parallel system that, in contrast, aim at homogeneous and controllable resources. To suggest an algorithm that can fully reflect the characteristics of a grid system, our research is focused on examining the type of information used in current scheduling algorithms and consequently, deriving factors that could develop algorithms further. The results from the analysis of these algorithms not only show that static information of resources such as capacity or the number of processors can facilitate the scheduling algorithms but also verified a decrease in efficiency in case of utilizing real time load information of resources due to the intrinsic characteristics of a grid system relatively long computing time, and the need for the means to evade unfeasible resources or ones with slow processing time. In this paper, we propose a new algorithm, which is revised to reflect static information in the logic of WQR(Workqueue Replication) algorithms and show that it provides better performance than the one used in the existing method through simulation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.9
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• pp.1001-1009
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• 2016

In LTE networks, the base station transmits control information over the physical downlink control channel (PDCCH) including scheduling grants, which are used to indicate the resources that the user equipment uses to send data to the base station. Because the size of the PDCCH message and the number of the PDCCH transmissions increase in proportion to the number of user equipments, the overhead of the PDCCH may cause serious network congestion problems in the narrowband LTE (NB-LTE) system. This paper proposes the compact PDCCH information bit allocation to reduce the size of the PDCCH message and evaluates the performance of the semi-persistent scheduling (SPS) in the NB-LTE system. The simulation results show that the SPS can significantly reduce the signaling overhead of the PDCCH and therefore increase the system utilization.