• Journal of Advanced Navigation Technology
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• v.13 no.3
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• pp.372-377
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• 2009

This paper evaluates the performance of three methods for predicting resources requested by mobile's calls and a call admission algorithm based on these predicting methods respectively in wireless networks. The first method is based on Wiener prediction model and the second method is based on the MMOSPRED algorithm and the third method is based on the neural network. The proposed call admission algorithm is based on prioritized handoff call in resource allocation. The resources for future handoff calls are therefore predicted and reserved in advance, and then new calls are admitted as long as the remaining resources are sufficient. We compare their performances in terms of prediction error, new call blocking and handoff dropping probabilities by simulation. Results show that the CAC based on Wiener prediction model performs favorably due to exact resources prediction.

• The Journal of Korean Association of Computer Education
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• v.13 no.1
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• pp.53-64
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• 2010

In this paper, we tried to enable a mobile device as a resource to access to mobile grid networks. By advanced Internet techniques, the use of mobile devices has been rapidly increased. Some researches in mobile grid computing tried to combine grid computing with mobile devices. However, according to intrinsic properties of mobile environments, mobile devices have many considerations, such as mobility management, disconnected operation, device heterogeneity, service discovery, resource sharing, security, and so on. To solve these problems, there are two trends for mobile grid computing: a proxy-based mobile grid architecture and an agent-based mobile grid architecture. We focus on a proxy-based mobile grid architecture with IP-paging, which can easily manage idle mobile devices and grid resource status information. Also, we use SIP(Session Initiation Protocol)to support mobility management, mobile grid services. We manage variation of mobile device state and power by paging cache. Finally, using the candidate set and the reservation set of resources, we perform task migration. The performance evaluation by simulation, shows improvement of efficiency and stability during execution.

• Journal of KIISE:Information Networking
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• v.34 no.2
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• pp.120-133
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• 2007

A multicast tree includes several, possibly a large number of, paths connecting source-receiver pairs, and network failure may disable part of the multicast tree. Reconstruction of the entire multicast tree to recover from a component failure is highly undesirable, because some group members have to suffer service disruptions even though the communication paths to/from them are not affected by the failure. To limit reconfiguration region and to maximize the likelihood of successful reconfiguration, we propose and evaluate a pre-planned reconfiguration policy for QoS multicast sessions. Specifically, we equip a reconfiguration path (RP) with each end-to-end path that connects a source-receiver pair in the multicast tree, and reserve resources in advance along the RPs. Efficient resource-sharing techniques are applied to reduce the amount of resources reserved for RPs but not used in the absence of failures. This way, we prevent uncontrolled competition among different multicast sessions which may simultaneously try to recover from failures. We evaluate the performance of the proposed scheme using simulation on randomly-generated networks. We use the shortest-path routing for QoS multicast sessions, and simulate both source-based and shared multicast trees. The evaluation results indicates that successful pre-planned reconfiguration can be achieved for all group members with reasonable overhead. Our scheme is also shown to adapt well to dynamic changes of group membership.

• The KIPS Transactions:PartB
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• v.8B no.5
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• pp.523-532
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• 2001

A Critical issue in the performance of a video-on-demand system is the required I/O bandwidth of the Video server in order to satisfy clients requests, and it is the crucial resource that may cause delay increasingly. Several approaches such as batching and piggybacking are used to reduce the I/O demand on the video server through sharing. Bathing approach is to make single I/O request for storage server by grouping the requests for the same object. Piggybacking is th policy for altering display rates of requests in progress for the same object to merge their corresponding I/O streams into a single stream, and serve it as a group of merged requests. In this paper, we propose a reservation-based hybrid disk bandwidth reduction policy that dynamically reserves the I/O stream capacity of a video server for popular videos according to the loads of video server in order to schedule the requests for popular videos immediately. The performance of the proposed policy is evaluated through simulations, and is compared with that of bathing and piggybacking. As a result, we know that the reservation-based hybrid disk bandwidth reduction policy provides better probability of service, average waithing time and percentage of saving in frames than batching and piggybacking policy.

• The KIPS Transactions:PartC
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• v.11C no.6 s.95
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• pp.807-814
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• 2004

This paper researches and evaluates a bandwidth reallocation mechanism for efficient DiffServ QoS support in MPLS networks by monitoring the network traffic status and reallocating unused bandwidth. While the Differentiated Services in MPLS Networks architecture provides QoS management through the RSVP resource reservation, this mechanism is based on a static provisioning of resource. But this approach can lead to waste bandwidth in some service classes or, leave some service classes' resource starved. This paper presents the bandwidth reallocation dynamically based on network traffic status for bandwidth usage maximization.

• Proceedings of the Korean Information Science Society Conference
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• 2006.06a
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• pp.211-213
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• 2006

실시간으로 변화하는 컴퓨터 통신 환경에서 멀티미디어 응용 프로그램은 QoS를 만족하기 위해 안정적으로 튜닝 되고 재구성되는 것이 필요하다. 그러나 안정적으로 QoS를 보장하는 것은 응용 프로그램의 자원 예약이나 실시간 보장과 같은 메카니즘을 제공하지 않은 일반적인 목적의 시스템 상에서 수행될 때 많은 어려움을 가지게 된다. 특히, 예측 불가능한 개방형 환경에서 최우선 자원 할당에 의해 발생되는 자원의 유효성에 대응하기 위해 QoS 적응은 수행되어야 한다. 그러나 적응을 언제, 어떻게 조정해야 하고 폭 넓은 범위에서 응용 프로그램에 어떻게 적용시킬지를 알기 위해 일반적인 알고리즘을 제시해야할 필요가 있다. 이러한 목적을 위해, 본 논문에서는 멀티미디어 어플리케이션의 파라미터를 모델링하고, 파라미터간의 관계를 정량적으로 얻기 위해 계층적 QoS 프로빙 알고리즘을 적용한다. 이것을 기반으로 설계된 베이지안 네트워크를 이용하여 불확실한 정보를 확률값으로 처리함으로써 적응 행동을 예측하도록 한다. 마지막으로 실제 실험을 통해 제안된 미들웨어의 유용성을 확인한다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.12
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• pp.2319-2326
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• 2007

Recently, various systems are being developed for efficiently assignment and management of such resources as seats of airplane, train, bus, theater, and library. If it occurs the exceed demand for the limited seat resource, the system has much difficulty for the seat resource management and assignment efficiently. The existed allocation and management methods were processed using the centralization management of the limited seat resource. But these methods cannot consider the preference of each user, and these not support the fairness of usage for each person. Accordingly, we design and implement the seat assignment system based on the customer-driven for the seat management in the reading room of library, customer selects directly for the fairness of seat.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.4B
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• pp.444-454
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• 2004

To support diverse transmission requirements of multimedia applications, Quality of Service (QoS) should be provided in the Internet, where only the best-effort service is available. In this paper, we describe our recent effort on the implementation and verification of an extendable and flexible QoS allocation and resource management system based on the bandwidth broker model for realizing the IETF differentiated service (DiffServ). Focusing on the bandwidth issue over single administrative domain, the implemented system provides real-time resource reservation and allocation, delayed call admission control, simple QoS negotiation between sewer and users, and simple resource monitoring. The implemented system is verified by evaluating the performance of a resource-intensive application over the real-world testbed network.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.9A
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• pp.1067-1074
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• 2004

In the wireless mobile networks, it IS important to provide the quality-of-service (QoS) guarantees as they are increasingly expected to support the multimedia applications Although the QoS provisioning problem arises in the wire-line networks as well, the mobility of hosts and the scarcity of bandwidth make QoS provisioning a challenging task in wireless mobile networks. The resource allocation to multimedia applications of varying QoS reqUlrement 15 a complex issue. In this paper, we propose a new adaptive resource allocation scheme based on the concept of the resource reservation and the renegotiation in order to guarantee the QoS of the real-tune traffic. The proposed scheme is aimed at improving the perfonnance in terms of the new call blocking rate, the bandoff dropping rate, and the bandwIdth utilization.

• The KIPS Transactions:PartC
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• v.9C no.2
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• pp.297-306
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• 2002

Continuous multimedia applications require a guaranteed retricval and transfer rate of streaming data, which conventional file server mechanism generally does not provide. In this paper we describe a dynamic negotiated admission control and dick bandwidth scheduling framework for Continuous Media (CM : e.g., video) servers. The framework consists of two parts. One is a reserve-based admission control mechanism and the other part is a scheduler for continuous media streams with dynamic resource allocation to achieve higher utilization than non-dynamic scheduler by effectively sharing available resources among contending streams to improve overall QoS. Using our policy, we could increase the number of simultaneously running: clients that coo]d be supported and cot]d ensure a good response ratio and better resource utilization under heavy traffic requirements.