• Journal of Communications and Networks
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• v.15 no.6
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• pp.614-634
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• 2013

The proliferation of real-time multimedia services requires huge amounts of data transactions demanding strict quality-of-service (QoS) guarantees. Multicast transmission is a promising technique because of its efficient network resource utilization. However, high head-of-line (HOL) blocking probability and lack of service-specific QoS control should be addressed for practical implementations of multicast networks. In this paper, a topology aware fanout set division (TAFD) scheme is proposed to resolve these problems. The proposed scheme is composed of two techniques that reduce HOL blocking probability and expedite packet delivery for large-delay branches regarding multicast tree topology. Since management of global topology information is not necessary, scalability of the proposed scheme is guaranteed. Mathematical analysis investigates effects of the proposed scheme and derives optimal operational parameters. The evaluation results show that the TAFD scheme achieves significant delay reduction and satisfies required delay bounds on various multicast networks.

• The KIPS Transactions:PartC
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• v.13C no.7 s.110
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• pp.933-938
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• 2006

Different multimedia services over networks not only require different amounts of bandwidth but also have different Qualify of Service (QoS) requirements. For example, QoS guarantees for higher priority calls is an important issue in multimedia communication networks. In this paper, we develop an adaptive bandwidth management algorithm, which is able to provide QoS guarantees for higher priority calls while accommodating as many heterogeneous multimedia call connections as possible. Our scheme, based on reservation and bandwidth adaptation, manages bandwidth based on real time estimates of current network conditions. Simulation results indicate the superior performance of our scheme providing excellent trade off between contradictory requirements.

• Journal of Korea Multimedia Society
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• v.17 no.12
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• pp.1453-1460
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• 2014

WFQ (Weighted Fair Queuing) provides not only fairness among traffic flows in using bandwidth but also guarantees the Quality of Service (QoS) that individual flow requires, which is why it has been applied to the resource reservation protocol (RSVP)-capable router. The RSVP allocates an enough resource to satisfy both the rate and end-to-end delay requirements of the flow in the condition of no packet loss, and the WFQ scheduler guarantees those QoS requirements with the allocated resource. In practice, however, most QoS-guaranteed services allow a degree of packet loss, especially from 0.1% to 3% for Voice over IP. This paper discovers that the packet loss rate of each traffic flow is determined by only its time-stamp adjustment value, and then enhances the WFQ to provide a differentiated packet loss guarantee under general traffic conditions in terms of both traffic characteristics and QoS requirements. The performance evaluation showed that the proposed WFQ could increase the utilization of bandwidth by 8~11%.

• Journal of KIISE:Information Networking
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• v.29 no.6
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• pp.722-737
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• 2002

As the number of multimedia applications increases, various protocols and architectures have been proposed to provide QoS(Quality of Service) guarantees in the Internet. Most of these techniques, though, bear inherent contradiction between the scalability and the capability of providing QoS guarantees. In this paper, we propose a protocol, named DQSP(Dynamic QoS Support Protocol), which provides the dynamic resource allocation and admission control for QoS guarantees in a scalable way. In DQSP, the core routers only maintain the per source-edge router resource allocation state information. Each of the source-edge routers maintains the usage information for the resources allocated to itself on each of the network links. Based on this information, the source edge routers perform admission control for the incoming flows. For the resource reservation and admission control, DQSP does not incur per flow signaling at the core network, and the amount of state information at the core routers depends on the scale of the topology instead of the number of user flows. Simulation results show that DQSP achieves efficient resource utilization without incurring the number of user flow related scalability problems as with IntServ, which is one of the representative architectures providing end-to-end QoS guarantees.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.2B
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• pp.100-107
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• 2007

Recently, a study of BcN(Broadband convergence Network) is progressing continuously, and it is important to improve the quality of the service according to subscribers because a scale of network is about to be larger. It is more important to manage QoS(Quality of Service) of all subscribers in layer 2 than layer 3 network since managing it in layer 3 network cost both additional processes and large hardware. Moreover, QoS based on Best-Effort service has been developed because tots of subscribers should use limited resource in BcN. However, they want to be supplied with different service even though they pay more charge. Therefore, it is essential to assign the different bandwidth to subscribers depending on their level of charge. The method of current Rate Limiter limits the bandwidth of each port that does not offer fair service to subscribers. The Rate Limiter proposed in this paper limits bandwidth according to each subscriber. Therefore, subscribers can get fair service regardless of switch structure. This new Rate Limiter controls the bandwidth of subscribers according to the information of learning subscriber and manages maximum performance of Ethernet switch and QoS.

• Proceedings of the Korean Information Science Society Conference
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• 2000.04a
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• pp.89-91
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• 2000

멀티미디어 응용이 점점 널리 사용되면서 멀티미디어 응용에 적합한 태스크 모델의 연구가 진행되었으나, 기존의 태스크 모델은 멀티미디어 응용의 특성을 충분히 반영하지 못하였다. 본 논문에서는 멀티미디어 응용의 자원 사용량의 패턴에 기반한 확률적 멀티프레임 태스크 모델(PMF)을 제시하고, PMF를 멀티미디어 응용의 스케줄링에 적용하여 CPU 자원을 효율적으로 이용하면서 멀티미디어 응용에게 통계적 QoS를 제공할 수 있는 방안을 제시한다. 또한, 다양한 스케줄링 기법을 채용한 모의실험을 통해 제시한 태스크 모델이 자원을 최대한 활용 하면서 응용에게 QoS를 보장할 수 있음을 보인다.

• The Transactions of the Korea Information Processing Society
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• v.7 no.9
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• pp.2940-2947
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• 2000

In the wireless ATM networks, a Medium Access Control (MAC) protocol is required to support an integrated mix of multimedia traffic services. The MAC protocol should be designed in a way that the limited wireless bandwidth can be efficiently utilized maximizing the Quality of Service (QoS) guarantees for various traffic service classes. In this paper, a Dynamic Resource Allocation-based MAC protocol, which satisfies QoS of each traffic service class in the wireless ATM environment, is proposed. The proposed MAC protocol adopts the dynamic channel allocation schemes for a mix of different traffic service classes. The suggested MAC protocol is designed to provide the QoS guarantees for Constant Bit Rate (CBR) or real-time Variable Bit Rate (VBR) traffic through fixed or dynamic reservation. For Available Bit Rate (ABH) traffic, which has the lowest priority among the traffic classes, large improvement in delay by reserving the minimum bandwidth is shown. And for real-time VBR traffic, increase in throughput of transmission is demonstrated because of bandwidth, which is allocated through contention at the initial phase and without contention thereafter.

• Journal of Computing Science and Engineering
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• v.11 no.3
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• pp.100-108
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• 2017

In the field of Internet of Things (IoT), smarter embedded devices offer functions via web services. The Quality-of-Service (QoS) prediction is a key measure that guarantees successful IoT service applications. In this study, a collaborative filtering method is presented for predicting response time of IoT service due to time-awareness characteristics of IoT. First, a calculation method of service response time similarity between different users is proposed. Then, to improve prediction accuracy, initial similarity values are adjusted and similar neighbors are selected by a similarity threshold. Finally, via a densified user-item matrix, service response time is predicted by collaborative filtering for current active users. The presented method is validated by experiments on a real web service QoS dataset. Experimental results indicate that better prediction accuracy can be achieved with the presented method.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.10
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• pp.8-15
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• 2003

In this paper, we address how to provide absolute differentiated services for optical burst switching (OBS) networks based on dynamic wavelength assignment. Unlike existing quality of service (QoS), such as buffer-based and offset-time based scheme, our proposed dynamicvirtual lambda partitioning (DVLP) scheme does not mandate any buffer or extra offset time, but can achieve absolute service differentiation between classes. This new DVLP scheme shares wavelength resources based on several different priority of classes in an efficient and QoS guaranteed manner. The performance results show that the proposed scheme effectively guarantees a target blocking probability of each traffic classes both in Poisson and Self-similar traffic environment.

• The KIPS Transactions:PartC
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• v.13C no.5 s.108
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• pp.607-612
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• 2006

Universal Mobile Telecommunications System (UMTS) and Wireless Local Area Network (WLAN) have been developed independently. Then, many researchers have studied UMTS-WLAN interworking architecture for the efficiency. However, the transmission capacity difference of two networks causes the transmission quality degradation. Therefore, this paper proposes a UMTS-WLAN interworking architecture for Quality of Service (QoS). The proposed architecture is based on tight coupling and dynamically guarantees QoS by the mobility prediction method. The proposed architecture is simulated by ns-2. Performance experimental results show that the proposed architecture reduces the handover dropping probability comparing with the existing method and enhances the amount of receiving packets comparing with the method without guaranteeing QoS.