• Title/Summary/Keyword: Optimal Timeslot Allocation

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QoS-based Optimal Timeslot Allocation for MF-TDMA Broadband Satellite Systems (MF-TDMA 광대역 위성시스템을 위한 QoS 기반 최적 타임슬롯 할당 체계)

  • Chang Kun-Nyeong;Lee Ki-Dong;Park You-Jin
    • Journal of the Korean Operations Research and Management Science Society
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    • v.29 no.4
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    • pp.141-157
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    • 2004
  • In this paper, we consider broadband satellite systems using MF-TDMA(Multi-Frequency Time Division Multiple Access) scheme. First, we analyze return link, superframe structure, and QoS( Quality of Service) parameters in broadband satellite systems, and mathematically formulate the QoS-based optimal timeslot allocation problem as a nonlinear integer programming problem for broadband satellite systems with clear-sky and rain-fade satellite terminals, and multiple data classes. Next, we modify the proposed problem to solve it within in a fast time, and suggest the QoS-based optimal timeslot allocation scheme. Extensive simulation results show that the proposed scheme finds an optimal solution or a near optimal solution within 5ms at Pentium IV PC.

Optimal Buffer and Timeslot Allocation Scheme for Broadband Satellite Networks (광대역 위성 네트워크를 위한 최적 버퍼 및 타임슬롯 할당 체계)

  • Chang Kun-Nyeong;Park You-Jin
    • Journal of the Korean Operations Research and Management Science Society
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    • v.31 no.1
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    • pp.117-129
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    • 2006
  • In this paper, we consider broadband satellite networks using MF-TDMA (Multi-Frequency Time Division Multiple Access) scheme. We analyze the number of expected lost packets in each terminal, and mathematically formulate optimal buffer and timeslot allocation model to minimize the weighted sum of the numbers of expected lost packets. We also suggest optimal buffer and timeslot allocation scheme based on Lagrangean relaxation technique to solve the proposed model in a fast time. Extensive experiments show that the proposed scheme provides encouraging results.

Real-time Integrated Timeslot and Code Allocation Scheme for the CDMA/TDD System Supporting Voice and Data Services (음성 및 데이터 서비스를 지원하는 CDMA/TDD 시스템을 위한 실시간 통합 타임슬롯 및 코드 할당 체계)

  • Chang, Kun-Nyeong;Lee, Ki-Dong
    • Korean Management Science Review
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    • v.25 no.2
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    • pp.25-42
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    • 2008
  • CDMA/TOD with asymmetric capacity allocation between uplink and downlink is a highly attractive solution to support the next generation mobile systems. This is because flexible asymmetric allocation of capacity to uplink and downlink usually improves the utilization of the limited bandwidth. In this paper, we mathematically formulate an optimal timeslot and code allocation problem, which is to maximize the total utility considering the numbers of codes(channels) allocated to each data class and the forced terminations of previously allocated codes. We also suggest a real-time integrated timeslot and code allocation scheme using Lagrangean relaxation and subgradient optimization techniques. Experimental results show that the proposed scheme provides high-quality solutions in a fast time.

Improving Efficiency of Timeslot Assignment for Non-realtime Data in a DVB-RCS Return Link: Modeling and Algorithm

  • Lee, Ki-Dong;Cho, Yong-Hoon;Lee, Ho-Jin;Oh, Deock-Gil
    • ETRI Journal
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    • v.25 no.4
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    • pp.211-218
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    • 2003
  • This paper presents a dynamic resource allocation algorithm with multi-frequency time-division multiple access for the return link of interactive satellite multimedia networks such as digital video broadcasting return channel via satellite systems. The proposed timeslot assignment algorithm, called the very efficient dynamic timeslot assignment (VEDTA) algorithm, gives an optimal assignment plan within a very short period. The optimality and computational efficiency of this algorithm demonstrate that it will be useful in field applications.

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Optimal buffer and timeslot allocation scheme for interactive GEO satellite networks (대화형 GEO 위성 네트워크를 위한 최적 버퍼 및 타임슬롯 할당 체계)

  • Jang, Geun-Nyeong;Park, Yu-Jin
    • Proceedings of the Korean Operations and Management Science Society Conference
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    • 2005.05a
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    • pp.248-254
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    • 2005
  • 본 논문에서는 대화형 GEO 위성 네트워크에서 패킷 손실량 기대값의 총합을 최소화하는 최적 버퍼 및 타임슬롯 할당 체계를 제시한다. 이를 위해 각 단말에서의 패킷 손실량 기대값을 분석하고, 최적 버퍼 및 타임슬롯 할당 방법을 구하기 위한 최적화 모형을 정형화하고, 정형화된 모형을 빠른 시간 내에 해결할 수 있는 방법을 제시한다. 실험을 통해 제시한 방법이 기존 방법에 비해 패킷 손실량 기대값의 총합을 의미 있게 감소시킴을 보인다.

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Simulation of Contaminant Draining Strategy with User Participation in Water Distribution Networks

  • Marlim, Malvin S.;Kang, Doosun
    • Proceedings of the Korea Water Resources Association Conference
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    • 2021.06a
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    • pp.146-146
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    • 2021
  • A contamination event occurring in water distribution networks (WDNs) needs to be handled with the appropriate mitigation strategy to protect public health safety and ensure water supply service continuation. Typically the mitigation phase consists of contaminant sensing, public warning, network inspection, and recovery. After the contaminant source has been detected and treated, contaminants still exist in the network, and the contaminated water should be flushed out. The recovery period is critical to remove any lingering contaminant in a rapid and non-detrimental manner. The contaminant flushing can be done in several ways. Conventionally, the opening of hydrants is applied to drain the contaminant out of the system. Relying on advanced information and communication technology (ICT) on WDN management, warning and information can be distributed fast through electronic media. Water utilities can inform their customers to participate in the contaminant flushing by opening and closing their house faucets to drain the contaminated water. The household draining strategy consists of determining sectors and timeslots of the WDN users based on hydraulic simulation. The number of sectors should be controlled to maintain sufficient pressure for faucet draining. The draining timeslot is determined through hydraulic simulation to identify the draining time required for each sector. The effectiveness of the strategy is evaluated using three measurements, such as Wasted Water (WW), Flushing Duration (FD), and Pipe Erosion (PE). The optimal draining strategy (i.e., group and timeslot allocation) in the WDN can be determined by minimizing the measures.

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Packet Scheduling in Interactive Satellite Return Channels for Mobile Multimedia Services Using Hybrid CDMA/TDMA

  • Lee Ki-Dong;Kim Ho-Kyom;Lee Ho-Jin
    • Proceedings of the Korean Operations and Management Science Society Conference
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    • 2003.05a
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    • pp.744-748
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    • 2003
  • Developing an interactive satellite multi­media system, such as a digital video broadcasting (DVB) return channel via satellite (RCS) system, is gaining popularity over the world To accommodate the increasing traffic demand we are motivated to investigate an alternative for improving return channel utilization We develop an efficient method for optimal packet scheduling in an interactive satellite multimedia system using hybrid CDMA/TDMA channels. We formulate the timeslot-code assignment problem as a binary integer programming (BIP) problem, where the throughput maximization is the objective, and decompose this BIP problem into two sub-problems for the purpose of solution efficiency. With this decomposition, we promote the computational efficiency in finding the optimal solution of the original BIP problem Since 2001, ETRI has been involved in a development project where we have successfully completed an initial system integration test on broadband mobile Internet access via Ku-band channels using the proposed resource allocation algorithm.

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Optimal Timeslot Allocation for MF-TDMA Broadband Satelite Systems (MF-TDMA 광대역 위성시스템을 위한 최적 타임슬롯 할당 체계)

  • 장근녕;이기동;이호진
    • Proceedings of the Korean Operations and Management Science Society Conference
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    • 2003.05a
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    • pp.448-455
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    • 2003
  • 본 논문에서는 MF-TDMA(Multi Frequency - Time Division Multiple Access)체계를 이용하는 광대역 위성 시스템의 리턴 링크를 대상으로 최저타임슬롯 할당 체계를 제시한다. 이를 위해 먼저 clear-sky RCST와 rain-fade RCST가 존재하고 복수의 서비스 및 지연 클래스가 존재하는 광대역 위성 시스템을 대상으로 MF-TDMA 체계 하에서 최적 타임슬롯 할당 체계를 제시한다. Phase 1에서는 clear-sky TRF타임슬롯들의 집합과 rain-fade TRF타임슬롯들의 집합을 결정하고, Phase 2에서는 각 RCST의 각 서비스/지연 클래스에 할당되는 타임슬롯의 수를 결정하고, Phase 3에서는 각 RCST의 각 서비스/지연 클래스에 할당된 타임슬롯들의 스케줄을 결정한다. 마지막으로 불균등 수요 데이터를 활용하여 제시한 최적 타임슬롯 할당 체계의 성능을 분석한다. 성능 분석 결과 제시한 최적 타임슬롯 할당 체계는 빠른 시간 내에 최적해 또는 최적해와 아주 가까운 해를 안정적으로 구한다는 사실을 확인할 수 있었다.

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