• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.97-100
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• 1997

Fieldbuses are used as the lowest level communication network for real-time communication in factory automation and process control systems. Data generated from field devices can be divided into three categories: sporadic real-time, periodic real-time and non real-time data. Since these data share one fieldbus network medium, it needs a method that allocate the limited bandwidth of fieldbus network to the sporadic real-time, periodic real-time and non real-time traffic. This paper introduces an implementation method of bandwidth allocation scheme introduced in [51 on PROFIBUS. Using the modified PROFIBUS FDL(Fieldbus Data Link layer), the bandwidth allocation scheme introduced in [51 is verified by the experiments.

• International Journal of Control, Automation, and Systems
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• v.6 no.4
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• pp.596-606
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• 2008

In this paper, we present a co-design methodology of dynamic optimal network-bandwidth allocation (ONBA) and adaptive control for networked control systems (NCSs) to optimize overall control performance and reduce total network-bandwidth usage. The proposed dynamic co-design strategy integrates adaptive feedback control with real-time scheduling. As part of this co-design methodology, a "closed-loop" ONBA algorithm for NCSs with communication constraints is presented. Network-bandwidth is dynamically assigned to each control loop according to the quality of performance (QoP) information of each control loop. As another part of the co-design methodology, a network quality of service (QoS)-adaptive control design approach is also presented. The idea is based on calculating new control values with reference to the network QoS parameters such as time delays and packet losses measured online. Simulation results show that this co-design approach significantly improves overall control performance and utilizes less bandwidth compared to static strategies.

• The KIPS Transactions:PartB
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• v.17B no.6
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• pp.413-420
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• 2010

In this paper, we propose a scheme for dynamic allocating network bandwidth based on the playback buffer levels of the clients in a distributed mobile multimedia system. In this scheme, the amount of bandwidth allocated to serve a video request depends on the buffer level of the requesting client. If the buffer level of a client is low or high temporarily, more or less bandwidth will be allocated to serve it with an objective to make it more adaptive to the playback situation of this client. By employing the playback buffer level based bandwidth allocation policy, fair services can also be provided to the clients. In order to support high quality video playbacks, video frames must be transported to the client prior to their playback times. The main objectives in this bandwidth allocation scheme are to enhance the quality of service and performance of individual video playback such as to minimize the number of dropped video frames and at the same time to provide fair services to all the concurrent video requests. The performance of the proposed scheme is compared with that of other static bandwidth allocation scheme through extensive simulation experiments, resulting in the 4-9% lower ratio of frames dropped according to the buffer level.

• Journal of Korea Multimedia Society
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• v.10 no.12
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• pp.1632-1644
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• 2007

Wireless Mesh Networks aim to attain large connectivity with minimum performance degradation, as network size is increase. As such, scalability is one of the main characteristics of Wireless Mesh Networks that differentiates it from other wireless networks. This characteristic creates the need for bandwidth efficiency strategies to ensure that network performance does not degrade as the size of the network increase. Several researches have been done to realize mesh networks. However, the researches conducted were mostly focused on a per TCP/IP layer basis. Also, the studies on bandwidth efficiency and bandwidth improvement are usually dealt with as separate issues. This paper aims to simultaneously study bandwidth efficiency and improvement. Aside from optimizing the bandwidth given a fixed capacity, the capacity is also increased using results of physical layer studies. In this paper, the capacity is improved by using the concept of non-overlapping channels for wireless communication. A channel allocation scheme is conceptualized to choose the transmission channel that would optimize the network performance parameters with consideration of chosen Quality of Service (QoS) parameters. Network utility maximization is used to optimize the bandwidth after channel selection. Furthermore, a routing scheme is proposed using the results of the network utilization method and the channel allocation scheme to find the optimal path that would maximize the network gain.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.15 no.3
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• pp.243-251
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• 1990

In this paper, the performances of bandwidth allocation strategies for wideband ISDN have been studied through the computer simulation. In general, the performance of multichannel bandwidth allocation method is superior to that of single channel bandwidth allocation method with respect to the throughtput, delay and blocking probability. Also, when the FIFO service scheme is used, it is shown that the throughput, delay characteristics and blocking probability for each traffic are almost similar. On the other hand, the priority service scheme being used, the performances of traffic with high priority are much better than that of traffic with low priority in the view of throughput, delay and blocking probability. Finally, for the FIFO and priority service disciplines, it can be seen that the multichannel bandwidth allocation method is more suitable than the single channel bandwidth allocation strategy in the case of serving various traffic.

• ETRI Journal
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• v.35 no.1
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• pp.18-26
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• 2013

This paper proposes an efficient bandwidth utilization (EBU) algorithm that utilizes the unused bandwidth in dynamic bandwidth allocation (DBA) of a 10-gigabit-capable passive optical network (XGPON). In EBU, an available byte counter of a queue can be negative and the unused remainder of an available byte counter can be utilized by the other queues. In addition, EBU uses a novel polling scheme to collect the requests of queues as soon as possible. We show through analysis and simulations that EBU improves performance compared to that achieved with existing methods. In addition, we describe the hardware implementation of EBU. Finally we show the test results of the hardware implementation of EBU.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.8
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• pp.719-724
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• 2013

Visible light communication based wireless personal area network (WPAN) has recently remained in the center of attention, as it shows a lot of promise to a be a perfect replacement for the contemporary Radio frequency (RF) communication at least in the indoor environment. A commercially deployable VLC based WPAN must support diverse traffic requirement for different kinds of service. In this paper, we have proposed an innovative bandwidth allocation scheme for VLC based WPAN. We wish to allocate bandwidth adaptively for users in a network where bandwidth for each user is allocated scalably. Our aim is to allow maximum number of users in a VLC based WPAN where each user is guaranteed their required QoS. The simulation results justify that the proposed scheme is better than the conventional scheme.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.12
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• pp.1632-1638
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• 2020

In this paper, we investigate a multi-beam satellite communication system where multiple terminals transmit information signals to the gateway via a satellite. The satellite is equipped with phased array antennas to form multiple spot beams of which bandwidths are not identically allocated. We formulate an optimization problem to maximize fairness of beam bandwidth allocation. In order to solve the problem, we propose two heuristic algorithms; iterative beam bandwidth allocation (IBBA) and request ratio-based beam bandwidth allocation (RRBBA) algorithms. The IBBA algorithm iteratively equalizes the ratio of allocated bandwidth of each beam to their resource request while the RRBBA algorithm allocates beam bandwidth calculated from the ratio. Simulation results show that the IBBA algorithm has close fairness performance to the optimum while the RRBBA algorithm has less performance than the IBBA algorithm at the price of reduced computational complexity.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.3A
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• pp.223-232
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• 2004

In this paper we propose the hierarchical-based dynamic bandwidth allocation algorithm for multi-class services in Ethernet-PON. The proposed algorithm consists of the high level scheduler in OLT and the low level scheduler in ONU. The hierarchical architecture is able to provide scalability and resource efficiency in Ethernet-PON which has the distributed nature of the scheduling domain, with queues and the scheduler located at a large distance from each other. We also propose three dynamic bandwidth allocation algorithms for the low level scheduler: Proportional Allocation algorithm, Maximum Request First Allocation (MRFA) algorithm and High Priority First Allocation (HPFA) algorithm. We implement the Ethernet-PON standardized in the IEEE 802,3ah using OPNET. We also evaluate and analyze the performance for the proposed algorithms in terms of channel utilization, queuing delay and the amount of remainder.

• Journal of Communications and Networks
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• v.15 no.1
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• pp.15-24
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• 2013

Provisioning of quality of service (QoS) is a key issue in any multi-media system. However, in wireless systems, supporting QoS requirements of different traffic types is a more challenging problem due to the need to simultaneously minimize two performance metrics - the probability of dropping a handover call and the probability of blocking a new call. Since QoS requirements are not as stringent for non-real-time traffic, as opposed to real-time traffic, more calls can be accommodated by releasing some bandwidth from the already admitted non-real-time traffic calls. If the released bandwidth that is used to handle handover calls is larger than the released bandwidth that is used for new calls, then the resulting probability of dropping a handover call is smaller than the probability of blocking a new call. In this paper, we propose an efficient call admission control algorithm that relies on adaptive multi-level bandwidth-allocation scheme for non-realtime calls. The scheme allows reduction of the call dropping probability, along with an increase in the bandwidth utilization. The numerical results show that the proposed scheme is capable of attaining negligible handover call dropping probability without sacrificing bandwidth utilization.