• ETRI Journal
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• v.27 no.1
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• pp.43-52
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• 2005

In this paper, we introduce an adaptive radio resource allocation for IP-based mobile satellite services. We also present a synchronous multibeam CDMA satellite system using an orthogonal resource sharing mechanism among downlink beams for the adaptive packet transmission. The simulation results, using a Ka-band mobile satellite channel and various packet scheduling schemes, show that the proposed system and resource allocation scheme improves the beam throughput by more than two times over conventional systems. The simulation results also show that, in multibeam satellite systems, a system-level adaptation to a user's channel and interference conditions according to user locations and current packet traffic is more efficient in terms of throughput improvement than a user-level adaptation.

• Journal of the Korea Society for Simulation
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• v.23 no.4
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• pp.111-119
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• 2014

The cloud environment need resource management method that to enable the big data issue and data analysis technology. Existing resource management uses the limited calculation method, therefore concentrated the resource bias problem. To solve this problem, the resource management requires the learning-based scheduling using resource history information. In this paper, we proposes the ART (Adaptive Resonance Theory)-based adaptive resource management. Our proposed method assigns the job to the suitable method with the resource monitoring and history management in cloud computing environment. The proposed method utilizes the unsupervised learning method. Our goal is to improve the data processing and service stability with the adaptive resource management. The propose method allow the systematic management, and utilize the available resource efficiently.

• The KIPS Transactions:PartC
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• v.16C no.4
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• pp.477-486
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• 2009

This paper proposes a dynamic bandwidth allocation (DBA) algorithm with adaptive maximum transmission window (DBA-AMTW) to increase channel utilization in Ethernet passive optical networks (EPONs). A polling mechanism in EPON determines channel utilization and puts constraints on DBA algorithm and scheduling. DBA algorithms based on interleaved polling with stop (IPS) allocate transmission windows to optical network units (ONU) considering requests of all ONUs. However channel idle time when any ONU does not transmit packets decreases channel utilization. Proposed DBA-AMTW improves efficiency of a network and allocates transmission windows effectively by appropriate DBA computation from REPORT messages of all ONUs. An adaptive maximum transmission window for each ONU determined by a DBA computation in the previous scheduling cycle. Simulation results show that the proposed DBA algorithm improves performance of throughput and average delay time.

• Journal of KIISE:Computing Practices and Letters
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• v.14 no.7
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• pp.743-747
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• 2008

Hierarchical overlay of heterogeneous wireless cells is considered as a promising architecture for next-generation wireless networks. This paper considers a special form of such architecture, WWAN/WLAN two-hop wireless relay networks. We first describe an undesirable scheduling phenomenon that the conventional proportional fair algorithm can cause in such networks. We, then, propose an enhanced proportional fair scheduling to remedy this problem. We demonstrate the performance of the proposed scheme via a simulation of UMTS/WLAN networks using NS-2.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.5A
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• pp.469-474
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• 2006

In this paper, we develop a method that derive the average sector throughput of HSDPA system. This proposed method reflects the effects of AMC, scheduling and multi-code transmission, and is performed by simple calculation procedures such as link budget analysis. Link budget table is used to estimate a cell coverage in general. We modify the link budget table in order to calculate C/I of the user according to the location of the user in CDMA packet system employing AMC. Furthermore, we utilize the proposed method to analyze the effects of scheduling and multi-code transmission.

• 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.

• Proceedings of the Korean Society of Computer Information Conference
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• 2018.07a
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• pp.15-16
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• 2018

본 논문에서는 다수의 센서 노드로 구성된 Internet of Things (IoT) 환경에서 새로운 환경에 대해 적응하는데 걸리는 시간을 줄이기 위한 새로운 스케줄링 기법을 제안한다. IoT 환경에서는 데이터 수집 및 전송 패턴이 사전에 정의되어 있지 않기 때문에 기존 정적인 Packet scheduling 기법으로는 한계가 있다. Q-learning은 네트워크 환경에 대한 사전지식 없이도 반복적 학습을 통해 Scheduling policy를 확립할 수 있다. 본 논문에서는 기존 Q-learning 스케줄링 기법을 기반으로 각 큐의 패킷 도착률에 대한 bound 값을 이용해 Q-table과 Reward table을 초기화 하는 새로운 Q-learning 스케줄링 기법을 제안한다. 시뮬레이션 결과 기존 기법에 비해 변화하는 패킷 도착률 및 서비스 요구조건에 적응하는데 걸리는 시간이 감소하였다.

• Proceedings of the Korean Information Science Society Conference
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• 2005.11a
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• pp.994-996
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• 2005

P2P 그리드 컴퓨팅 환경에서 피어의 자율성으로 인한 자원 제공의 휘발성과 피어의 이질적인 특성은 스케줄링 과정에서 해결해야 할 중요한 문제이다. 이에 본 논문에서는 이동 에이전트 기반 적응적 그룹 스케줄링 기법(Mobile Agent based Adaptive Group Scheduling Mechanism: MAAGSM)을 제안한다. 제안 기법은 피어의 특성 (즉, 자원제공자 자율성 고장, 자원제공자 가음용, 자원 제공 시간)에 따라 피어들을 동질적인 그룹(자원제공자 그룹)으로 구성한 후, 그룹에 적합한 다양한 스케줄링 알고리즘은 이동에이전트 기술을 이용하여 적용한다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.4
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• pp.1359-1375
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• 2015

Energy efficiency is critical for Wireless Sensor Networks (WSNs) since sensor nodes usually have very limited energy supply from battery. Sleep scheduling and nodes cooperation are two of the most efficient methods to achieve energy conservation in WSNs. In this paper, we propose an adaptive energy optimization approach for target tracking applications, called Energy-Efficient Node Coordination (EENC), which is based on the grid structure. EENC provides an unambiguous calculation and analysis for optimal the nodes cooperation theoretically. In EENC, the sleep schedule of sensor nodes is locally synchronized and globally unsynchronized. Locally in each grid, the sleep schedule of all nodes is synchronized by the grid head, while globally the sleep schedule of each grid is independent and is determined by the proposed scheme. For dynamic sleep scheduling in tracking state we propose a multi-level coordination algorithm to find an optimal nodes cooperation of the network to maximize the energy conservation while preserving the tracking performance. Experimental results show that EENC can achieve energy saving of at least 38.2% compared to state-of-the-art approaches.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2002.05a
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• pp.418-425
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• 2002

Bluetooth is an emerging technology expected to provide users with short range, low cost, pico-cellular wireless connectivity. The access to the medium for Bluetooth is based on a Master driven Time Division Duplexing (TDD) scheme. A slave transmits packets in the reverse slot only after the master polls the slave (or transmits a packet to the slave) in a forward slot. The master transmits packets to a slave in even slots while the slave transmits packets to the master in an odd slot. The way in which the master schedules packets transmission to slaves or polls them determines system performance. In this paper. we propose a traffic adaptive MAC scheduling scheme for Bluetooth. The proposed scheme adopts the ISAR (Intelligent Segmentation and Reassembly) policy, which adjusts the packet size to the traffic patterns, to adapt the polling frequency to the traffic conditions. Also for achieving fairness among master-slave connections our scheme includes a priority policy assinging prioritised service tlimes to each connection. By considering a scenario where a Bluetooth master is used as wireless access point to the Internet, we show that our scheme improve the system throughput and average queue delay with regard to a naive Round Robin (RR) scheme.