• 대한전기학회논문지:시스템및제어부문D
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• 제53권7호
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• pp.501-508
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• 2004

In this paper, a coordinated scheduling algorithm is proposed to reduce end-to-end delay in distributed control of systems. For the algorithm, the analysis of practical end-to-end delay in the worst case is performed priory with considering implementation of the systems. The end-to-end delay is composed of the delay caused by multi-task scheduling of operating systems, the delay caused by network communications, and the delay caused by asynchronous timing between operating systems and network communications. Through some simulation tests based on CAN(Controller Area Network), the proposed worst case end-to-end delay analysis is validated. Through the simulation tests, it is also shown that a real-time distributed control system designed to existing worst case delay cannot guarantee end-to-end time constraints. With the analysis, a coordinated scheduling algorithm is proposed here. The coordinated scheduling algorithm is focused on the reduction of the delay caused by asynchronous timing between operating systems and network communications. Online deadline assignment strategy is proposed for the scheduling. The performance enhancement of the distributed control systems by the scheduling algorithm is shown through simulation tests.

• 대한안전경영과학회지
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• 제11권3호
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• pp.131-138
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• 2009

This paper considers a coordinated scheduling problem between multi-suppliers and an manufacture. When the supplier has insufficient inventory to meet the manufacture's order, the supplier may use the expedited production and the expedited transportation. In this case, we consider a scheduling problem to minimize the total cost of suppliers and manufacture. We suggest an population management genetic algorithm with local search and crossover (GALPC). By the computational experiments comparing with general genetic algorithm, the objective value of GALPC is reduced by 8% and the calculation time of GALPC is reduced by 70%.

• 한국통신학회논문지
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• 제39C권7호
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• pp.538-545
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• 2014

본 논문은 다운링크 다중 선박 네트워크에서 동적으로 협력 전송(CoMP Transmission; Coordinated Multi-point Transmission)을 사용하는 유틸리티 함수를 도출하고 이를 기반으로 스케줄링 기법을 제안한다. 제안하는 스케줄링 기법은 수율과 공정성을 고려한 PF 형태의 유틸리티 함수를 최대화하기 위해서 매 프레임 협력적 전송 여부를 결정하고, 유틸리티 함수를 최대화하는 사용자를 선택한다. 특히 제안하는 유틸리티 함수 기반의 스케줄링 기법은 셀 경계 지역에 위치하는 사용자의 서비스 품질을 만족시키는 것을 목적으로 한다. 무선 환경에서 PF(Proportional Fair) 스케줄링을 사용할 때 제안한 유틸리티 함수를 기반으로 하는 스케줄링 기법의 성능을 평가한다. 모의실험을 통하여 제안하는 스케줄링 기법은 협력적 통신 네트워크와 비협력적 통신 네트워크를 동적으로 사용함으로써 전체 네트워크의 성능을 유지하면서 가장자리에 있는 선박의 성능을 향상시키는 것을 확인하였다.

• 한국전자파학회논문지
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• 제21권11호
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• pp.1311-1317
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• 2010

본 논문에서는 셀 간 협동을 수행하는 cooperative spatial multiplexing(CSM)의 상향 링크 용량을 개선하기 위한 무선 자원 관리 알고리즘을 제안한다. 인접 기지국에 대한 상향 링크 간섭을 억제하기 위해 각 이동국에서 독립적으로 수행되는 최대 송신 전력 제한 알고리즘을 제안한다. 또한 서비스 기지국과 간섭 기지국이 서로 상향 링크 채널 정보를 공유하는 coordinated CSM 시스템에서 셀 간 상향 링크 간섭 억제를 통해 용량을 개선하는 협동 스케줄링 알고리즘을 제안한다. 제안하는 알고리즘들은 낮은 복잡도로 동작하지만 인접 기지국의 상향 링크 간섭을 효과적으로 억제하여 상향 링크 시스템 용량을 증가시킬 수 있다.

• 대한전기학회논문지
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• 제36권5호
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• pp.319-327
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• 1987

This paper presents a dynamic programming sucdessive approximation algorithm for scheduling pumped storage hydro plants and shows how this method can be coordinated with the commitment of the thermal units of the system. The general object of operation of pumped hydrostorage plants is the minimization of the overall production cost and the maximization of generation reserves. The basic procedure used to obtain a combined pumped storage-unit commitment schedule is to execute the pumped storage scheduler and unit commitment scheduler iteratively. A combined DPSA algorithm has been presented to coordinate the scheduling of the pumped storage with the scheduling of the thermal units.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권11호
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• pp.3876-3895
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• 2014

Recently, Heterogeneous Network (HetNet) with Coordinated Multi-Point (CoMP) scheme is introduced into Long Term Evolution-Advanced (LTE-A) systems to improve digital services for User Equipments (UEs), especially for cell-edge UEs. However, Radio Resource Management (RRM), including Resource Block (RB) scheduling and Power Allocation (PA), in this scenario becomes challenging, due to the intercell cooperation. In this paper, we investigate the RRM problem for downlink transmission of HetNet system with Joint Processing (JP) CoMP (both joint transmission and dynamic cell selection schemes), aiming at maximizing weighted sum data rate under the constraints of both transmission power and backhaul capacity. First, joint RB scheduling and PA problem is formulated as a constrained Mixed Integer Programming (MIP) which is NP-hard. To simplify the formulation problem, we decompose it into two problems of RB scheduling and PA. For RB scheduling, we propose an algorithm with less computational complexity to achieve a suboptimal solution. Then, according to the obtained scheduling results, we present an iterative Karush-Kuhn-Tucker (KKT) method to solve the PA problem. Extensive simulations are conducted to verify the effectiveness and efficiency of the proposed algorithms. Two kinds of JP CoMP schemes are compared with a non-CoMP greedy scheme (max capacity scheme). Simulation results prove that the CoMP schemes with the proposed RRM algorithms dramatically enhance data rate of cell-edge UEs, thereby improving UEs' fairness of data rate. Also, it is shown that the proposed PA algorithms can decrease power consumption of transmission antennas without loss of transmission performance.

• 대한전기학회논문지:전력기술부문A
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• 제53권8호
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• pp.477-483
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• 2004

In competitive electricity markets, maintenance schedule is submitted by generation companies (GENCOs) and transmission companies (TRANSCOs), and coordinated by Independent System Operator (ISO) with the adequacy criterion. This paper presents an alternative coordination procedure by ISO on the maintenance schedule. In this paper, it is focused on modeling a coordination algorithm by ISO for the maintenance schedule based on the Simulated Annealing algorithm. The proposed model employs the minimum information such as generator capacity, forced outage rate and generator maintenance schedules. The objective function of this model represents minimization of adjustment on schedules submitted by GENCOs.

• IEIE Transactions on Smart Processing and Computing
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• 제5권5호
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• pp.346-348
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• 2016

Coordinated multi-point transmission is a candidate technique for next-generation cellular communications systems. We consider a system with multiple cells in which base stations coordinate with each other by sharing user channel state information, which mitigates inter-cell interference (ICI), especially for users located at the cell edge. We introduce a new user scheduling method that considers both ICI and intra-cell orthogonality. Due to the influence of ICI cancellation and the loss reduction of effective channel gain during the beamforming process, the proposed method improves the system sum rate, when compared to the conventional method, by an average of 0.55bps/Hz for different numbers of total users per cell.

• Journal of Communications and Networks
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• 제13권4호
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• pp.339-344
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• 2011

Base station coordination has received much attention as a means to reduce the inter-cell interference in cellular networks. However, this interference reducing ability comes at the expense of increased feedback, backhaul load and computational complexity. The degree of coordination is therefore limited in practice. In this paper, we explore the trade-off between capacity and feedback load in a cellular network with coordination clusters. Our main interest lies in a scenario with multiple fading users in each cell. The results indicate that a large fraction of the total gain can be achieved by a significant reduction in feedback. We also find an approximate expression for the distribution of the instantaneous signal to interference-plus-noise ratio (SINR) and propose a new effective scheduling algorithm.

• 한국통신학회논문지
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• 제37권8A호
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• pp.601-611
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• 2012

본 논문에서는, 다중 안테나 다중 사용자가 존재하는 3-cell 간섭 Broadcast 채널 (IFBC: interference broadcast channel) 에서 얻을 수 있는 공간 다중화 이득 (spatial multiplexing gain)에 대해서 소개한다. 이러한 공간 다중화 이득을 최대화하면서 총 수율을 높이기 위하여, 우리는 간섭 정렬 기법 (IA: interference alignment)에 스케쥴링 기법을 더한 방법을 제안하며, 이는 IFBC 환경에서 TDMA 기법보다 높은 수율 성능을 보인다. 최적의 스케쥴링 방법은 다중 사용자 이득을 이용하여 총 수율을 최대화하는 전수 조사 알고리즘을 이용한다. 또한, 전수 조사의 계산 복잡도가 매우 높기 때문에, 이를 효과적으로 줄이는 coordinated ascent 방법을 이용한 부최적 스케쥴링 방법도 제안 한다.