• 대한전자공학회논문지TC
• /
• 제41권8호
• /
• pp.45-53
• /
• 2004

본 논문에서는 Ethernet PON에서 가입자간 가중치 공평성을 보장하는 매체접근제어 알고리즘(IPDRR : Interleaved Polling with Deficit Round Robin)을 제안하고 성능 분석을 하였다. 제안된 IPDRR 기법의 목적은 기존 Ethernet PON의 TDMA나 Interleaved Polling with Adaptive Cycle Time (IPACT) 방식에서 전송하려는 프레임의 크기가 자신에게 할당된 슬롯의 잔여 대역을 초과하는 경우 이러한 대역폭을 사용하지 못하게 되어 낭비되던 잔여 대역폭을 줄이고, 각 ONU별로 서비스 받는 트래픽 대역폭을 가중치에 비례해서 제공함으로써 각각의 ONU에게 공평성을 보장하는 것이다. 본 논문에서는 시뮬레이션을 통해 기존 Ethernet PON의 IPACT 스케줄링 방법이 트래픽의 특성에 따라서 불공정함을 보이고, 제안된 IPDRR 알고리즘이 ONU 별 공평성과 낭비되던 잔여 대역폭을 제거함으로써 효율이 향상된 것을 보였다.

• Journal of Communications and Networks
• /
• 제10권1호
• /
• pp.28-37
• /
• 2008

In this paper, we investigate the problem of minimizing the average transmission power of users while guaranteeing the average delay constraints in time-varying uplink channels. We design a scheduler that selects a user for transmission and determines the transmission rate of the selected user based on the channel and backlog information of users. Since it requires prohibitively high computation complexity to determine an optimal scheduler for multi-user systems, we propose a low-complexity scheduling scheme that can achieve near-optimal performance. In this scheme, we reduce the complexity by decomposing the multiuser problem into multiple individual user problems. We arrange the probability of selecting each user such that it can be determined only by the information of the corresponding user and then optimize the transmission rate of each user independently. We solve the user problem by using a dynamic programming approach and analyze the upper and lower bounds of average transmission power and average delay, respectively. In addition, we investigate the effects of the user selection algorithm on the performance for different channel models. We show that a channel-adaptive user selection algorithm can improve the energy efficiency under uncorrelated channels but the gain is obtainable only for loose delay requirements in the case of correlated channels. Based on this, we propose a user selection algorithm that adapts itself to both the channel condition and the backlog level, which turns out to be energy-efficient over wide range of delay requirement regardless of the channel model.

• Journal of Communications and Networks
• /
• 제6권1호
• /
• pp.68-77
• /
• 2004

In the near future packet networks should support applications which can not predict their traffic requirements in advance, but still have tight quality of service requirements, e.g., guaranteed bandwidth, jitter, and packet loss. These dynamic characteristics mean that the sources can be made to modify their data transfer rates according to network conditions. Depending on the customer&; needs, network operator can differentiate incoming connections and handle those in the buffers and the interfaces in different ways. In this paper, dynamic QoS-aware scheduling algorithm is presented and investigated in the single node case. The purpose of the algorithm is in addition to fair resource sharing to different types of traffic classes with different priorities ?to maximize revenue of the service provider. It is derived from the linear type of revenue target function, and closed form globally optimal formula is presented. The method is computationally inexpensive, while still producing maximal revenue. Due to the simplicity of the algorithm, it can operate in the highly nonstationary environments. In addition, it is nonparametric and deterministic in the sense that it uses only the information about the number of users and their traffic classes, not about call density functions or duration distributions. Also, Call Admission Control (CAC) mechanism is used by hypothesis testing.

• 한국통신학회논문지
• /
• 제32권9A호
• /
• pp.878-887
• /
• 2007

본 논문은 HSDPA시스템에서 높은 전송 수율을 내면서도 기존 알고리즘에 비해 높은 공평성을 보장하는 스케줄링 알고리즘을 제안한다. 이 알고리즘은 할당하는 채널의 개수를 기지국에 수신된 SIR값에 매겨진 등급에 따라 다르게 할당하고 남는 채널을 다른 사용자에게 할당하여 전송 수율도 높으면서도 보다 많은 사용자에게 서비스를 하여 공평성도 향상시키는 기법이다. 실시간 및 비 실시간 데이터의 종류에 따라 전송 수율 및 공평성의 비율을 비교한 결과 기존의 알고리즘인 비례공정 알고리즘에 비해 높은 전송 수율을 보이고 MAX CIR과 유사한 전송 수율을 나타내고 MAX CIR 알고리즘에 비해 높은 공평성을 보여준다.

• Journal of Mechanical Science and Technology
• /
• 제20권12호
• /
• pp.2115-2123
• /
• 2006

The paper deals with the identification of Pareto optimal solutions using GA based coevolution in the context of multiobjective optimization. Coevolution is a genetic process by which several species work with different types of individuals in parallel. The concept of cooperative coevolution is adopted to compensate for each of single objective optimal solutions during genetic evolution. The present study explores the GA based coevolution, and develops prescribed and adaptive scheduling schemes to reflect design characteristics among single objective optimization. In the paper, non-dominated Pareto optimal solutions are obtained by controlling scheduling schemes and comparing each of single objective optimal solutions. The proposed strategies are subsequently applied to a three-bar planar truss design and an energy preserving flywheel design to support proposed strategies.

• 한국경영과학회:학술대회논문집
• /
• 한국경영과학회 1997년도 추계학술대회발표논문집; 홍익대학교, 서울; 1 Nov. 1997
• /
• pp.166-169
• /
• 1997

For parallel processing, the compiler partitions a loaded program into a set of tasks and makes a schedule for the tasks that will minimize parallel processing time for the loaded program. Building an optimal schedule for a given set of partitioned tasks of a program has known to be NP-complete. In this paper we introduce a GA(Genetic Algorithm)-based scheduling method in which a chromosome consists of two parts of a string which decide the number and order of tasks on each processor. An additional computation is used for feasibility constraint in the chromosome. By granularity theory, a partitioned program is categorized into coarse-grain or fine-grain types. There exist good heuristic algorithms for coarse-grain type partitioning. We suggested another GA adaptive to the coarse-grain type partitioning. The infeasibility of chromosome is overcome by the encoding and operators. The number of processors are decided while the GA find the minimum parallel processing time.

• 한국멀티미디어학회논문지
• /
• 제19권5호
• /
• pp.924-931
• /
• 2016

In this paper, Various network adaptive MAC scheduling technique is proposed to effectively overcome limits of narrow bandwidth and low transmission speed in underwater. UPFC(Underwater Packet Flow Control) is a technique to reduce both the number of transmission and transmission time using three types (Normal, Blocked, Parallel) of data transmission. In this technique, the load information, in which a transmission node have, is transmitted to destination node using marginal bit in reserved header. Then the transmitted information is referred to determine weighting factor. According to the weighting factor, scheduling is dynamically changed adaptively. The performance of UPFC is analyzed and flow control technique which can be applied to Cluster Based Network and Ad Hoc network as well.

• 한국통신학회논문지
• /
• 제29권11B
• /
• pp.974-979
• /
• 2004

IEEE 802.l1b에서는 기본서비스인 DCF와 QoS를 제공하기 위한 무경쟁 서비스인 PCF가 제공된다. DCF는 CSMA/CA(충돌을 회피하는 매체 접속 기법) 접속 프로토콜을 사용한다. 본 논문에서는 PCF를 수정하여 트래픽의 부하가 많아진 채널에 가충치를 두어 서비스하는 기법을 제시하였다. 스테이션 측으로부터 부분적인 큐의 정보를 받아 가중치를 계산하였으며 NS-2 시뮬레이터를 사용하여 PCF 기법을 수정한 기법의 우수성을 검증하였다.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2001년도 ICCAS
• /
• pp.129.4-129
• /
• 2001

The looper control of hot strip finishing mill is one of the most important control item in hot strip rolling mill process. Loopers are placed between finishing mill stands and control the mass flow of the two stands. Another important action of the looper is to control the strip tension which influences on the width of the strip. So it is very important to control both the looper angle and the strip tension simultaneously but the looper angle and the strip tension are strongly interacted by each other. There are many control schemes such as conventional, non-interactive, LQ(Linear Quadratic), Hinf and ILQ(Inverse Linear Quadratic), Adaptive(gain scheduling) control in the looper control system. In this paper, we present the modeling for the looper of a hot strip finishing mill to control the tension of the strip and suggest another control method.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제5권6호
• /
• pp.1101-1112
• /
• 2011

The Multiuser Eigenmode Transmission (MET) has generated significant interests in literature due to its optimal performance in linear precoding systems. The MET can simultaneously transmit several spatial multiplexing eigenmodes to multiple users which significantly enhance the system performance. The maximum number of users that can be served simultaneously is limited due to the constraints on the number antennas, and thus an appropriate user selection is critical to the MET system. Various algorithms have been developed in previous works such as the enumerative search algorithm. However, the high complexities of these algorithms impede their applications in practice. In this paper, motivated by the necessity of an efficient and effective user selection algorithm, a low complexity recursive user selection algorithm is proposed for the MET system. In addition, the fairness of the MET system is improved by using the combination of the proposed user selection algorithm and the adaptive Proportional Fair Scheduling (PFS) algorithm. Extensive simulations are implemented to verify the efficiency and effectiveness of the proposed algorithm.