• The KIPS Transactions:PartC
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• v.10C no.4
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• pp.479-484
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• 2003

In the current Internet, it is difficult for an Internet Phone to guarantee the QoS due to variable network conditions such as packet loss rate, delay and bandwidth. In addition, the QoS of an Internet Video Phone is more hard to guarantee because of video data. In this paper, we investigate application-level QoS control schemes that can adapt to variable network conditions, and describe an error control scheme and a congestion control scheme. Based on these QoS control schemes, we have designed and implemented an Internet Video Phone System that supports adaptive audio and video delivery. Through experiments, we found that the Internet Video Phone can reduce the packet loss rate considerably as well as adjust the transmission rate considering other TCP flows.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.12
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• pp.83-93
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• 2003

Differentiated service networks, based on bandwidth broker, perform the control and management of QoS provisioning for the QoS guaranteed services, However, the centralized bandwidth broker model has a scalability problem since it has centralized resource management for the admission control function of all call attempts, Therefore, in this paper, we proposea novel adaptive admission control mechanism according to the attempted call status for enhancing the scalability under the centralized bandwidth broker model in IP differentiated service networks, The proposed mechanism decouples the function of admission control from the bandwidth broker, So, the ingress edge node performs the admission control and the bandwidth broker performs the resource management and QoS provisioning, We also introduce an edge-to-edge path concepts and the ingress edge node performs the admission control under the allocated bandwidth to eachpath. The allocated bandwidth per path adaptively varies according to the status of the attempted calls, This mechanism can significantly reduce the number of communication message between the bandwidth broker and each edge node in the network and increase the bandwidth utilization via adaptable resource allocation, In this paper we study the adaptive admission control operation and show the efficient and extensive improvement through the performance evaluation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.5B
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• pp.442-448
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• 2006

This paper considers a home gateway(HG) that processes VOD services and controls home appliances. This paper proposes a PID algorithm-based adaptive bandwidth control method used in the HG, which guarantees QoS of incoming traffic such as VOD and real-time control data via control of outgoing traffic and have little effects on the CPU computation time. The proposed method is validated via implementation of real test environment.

• The KIPS Transactions:PartC
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• v.11C no.4
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• pp.429-438
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• 2004

This Paper Presents the control structure for incoming traffic from arbitrary node to Provide admission control in policy-based W network management structure using fuzzy logic control approach. The proposed control structure uses scheme for deciding network resource allocation depending on requirements predefined-policies and network states. The proposed scheme enhances policy adapting methods of existing binary methods, and can use resource of network more effectively to provide adaptive admission control, according to the unpredictable network states for predefined QoS policies. Simulation results show that the proposed controller improves the ratio of packet rejection up to 26%, because it Performs the soft adaption based on the network states instead of accept/reject action in conventional CAC(Connection Admission Controller).

• Proceedings of the Korea Information Processing Society Conference
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• 2000.10b
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• pp.1617-1620
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• 2000

최근 다양한 멀티미디어 서비스와 스트림 서비스의 급증과 사용자의 서비스 기대 증가로 인해 기존의 컴퓨팅 환경도 인터넷 기반의 분산 멀티미디어 환경으로 변화되고 있다. 이러한 다양한 요구를 만족시키기 위해서는 인터넷 환경과 실시간 특성들이 혼합된 폭넓은 범위의 분산 애플리케이션을 지원해야 하고, 이들 서비스간의 QoS(Quality of Service)를 보장해야 한다. 이를 위해 본 논문에서는 분산환경인 CORBA기반에서 자원들의 효과적인 관리와 서비스들간의 QoS를 보장하는 분산 QoS 관리 구조를 제시한다 즉, 클라이언트 측에 QoS 제어 관리 모들(QoS Control Management Module)을, 서버측에는 QoS 관리 모듈(QoS Management Module)을 각각 분산시켜 QoS 관리 및 제어를 분산 구조화함으로써 서버 시스템의 부하를 줄이고, 분산 서비스 응용에 지원을 확장할 수 있도록 하며 모듈들의 재사용이 가능하도록 하였다. 또한 분산 QoS 제어를 위해 실시간 협약(Negotiation) 및 동적 적응(Dynamic Adaptation)과정이 분산환경에서 수행되도록 기능 설계를 하였다. 이들 기능수행의 전반과정을 UML(Unified Modeling Lang uage)을 이용하여 순차적 다이어그램으로 기술하였다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.5
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• pp.941-950
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• 2001

In this paper, we present the integrated network architecture for supporting mobile IP in third generation mobile communication networks, and propose the end-to-end QoS control mechanisms of DiffServ and QoS control functions of each network element in the proposed network. First, the QoS supporting schemes of IMT-2000 are described. Second, the necessities of integrating the networks are discussed and the integrated architecture are proposed. Third, the mapping between wireless channels and DiffServ classes are presented. Finally, the end-to-end QoS control mechanisms are proposed. We also analyze the link level protocols with QoS provisioning for mobile multimedia assuming that the system support voice and data traffic simultaneously. In case of data traffic, the delay and throughput of SREJ ARQ and Type-1 Hybrid ARQ scheme are compared, and In case of voice traffic, the packet loss rate of BCH coding is analyzed according to the varying data traffic loads. The results indicate that the adaptive link level protocols are efficient to meet the QoS requirements while the complexities are increased.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.8B
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• pp.764-768
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• 2006

Over the years, the widespread proliferation of multimedia services has necessitated the development for an efficient network management. In this paper, we investigate the role of adaptive online pricing mechanism in order to manage effectively the network congestion problem. Our on-line approach is dynamic and flexible that responds to current network conditions. With a simulation study, we demonstrate that our proposed scheme enhances network performance and system efficiency simultaneously under widely diverse traffic load intensities.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.12A
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• pp.975-982
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• 2003

A connection admission control scheme is proposed that can seamlessly support QoS in face of handoff in mobile packet networks. The proposed scheme is based on the adaptive time-selective bandwidth reservation with the reduced signaling and computational overhead. The reservation parameters are adjusted dynamically to cope with user mobility. Throughout the computer simulations, the performance of the proposed scheme is evaluated. As a result, it is shown that the proposed scheme reduces handoff call blocking probability remarkably, while other parameters (new call blocking probability and bandwidth utilization efficiency) are slightly deteriorated.

• Proceedings of the Korean Information Science Society Conference
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• 1999.10c
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• pp.691-693
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• 1999

이동 컴퓨팅 환경은 유선망에 비하여 대역폭이 낮고, 호스트의 성능이 낮으며, 사용자의 이동에 따른 여러 가지 문제점이 나타난다. 이러한 이동 컴퓨팅 환경에서 멀티미디어 서비스를 제공하기 위해서는 무엇보다 QoS 제어가 중요하다. 따라서 본 논문에서는 이동 멀티미디어 컴퓨팅 환경의 동적 변화에 적응하고, 효율적으로 QoS를 제어하기 위하여 동적 우선순위를 기반으로 한 QoS 제어 기법을 제시한다. 동적 우선순위는 최초 연결성정 시에 결정되는 정적 우선순위와 보상을 기반으로 한 대역폭 변화값에 따라 결정되며, QoS 제어를 위한 기준으로 사용된다. 이러한 동적 우선순위는 낮은 QoS를 제공받은 MH(Mobile Host)가 핸드오프를 수행하여 새로운 셀로 이동한 경우에도 지속적으로 낮은 QoS를 제공받는 문제를 해결함으로써 공평하게 대역폭을 할당하는 장점이 있다.

• Proceedings of the Korean Information Science Society Conference
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• 1998.10a
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• pp.240-242
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• 1998

차세대 고속 무선망에서는 신뢰성이 높고 광전송로를 근간으로 하는 유선망의 멀티미디어 응용지원의 확장으로 유무선 종합 정보 통신망의 구현을 목표로 하고 있다. 현재 기존의 유선망에서는 멀티미디어 응용 지원을 위해 QoS Provisioning에 관한 많은 연구가 되어 있으나 무선망에서의 이동성과 무선 전파의 열악한 전송으로 인해 새로운 QoS Provisioning 방법에 관한 연구가 필수적이다. 본 논문에서는 지연에 민감한 실시간 트래픽의 QoS보장을 위하여 이동 터미널의 속도에 따라 이웃 셀의 대역폭을 예약함로써 핸드오프를 대비하고, 효육적인 무선 자원의 사용을 위해 적응적으로 예약된 대역폭의 양을 조정하는 방법을 제안한다. 또한, 트래픽 종류와 호의 종류, 터미널의 속도에 따라 다른 우선 순위를 부여하여 우선순위에 기반한 호 수락 제어 방법을 제안한다. 실험을 통하여 기존에 제안된 방법과 성능 비교한다.